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To explore the mechanism of the influence of Ni-Fe bimetallic catalyst for the producing high-value carbon nanotubes (CNTs) with clean hydrogen from waste plastic pyrolysis, the pyrolysis-catalysis of plastics were performed using a two stage fixed bed reaction system with Ni and Fe loading at variant molar ratios. The catalysts and produced carbon were analysed with various characterization method, including temperature-programed reduction/oxidation, X-ray diffraction, scanning electron microscopy or/and Raman spectroscopy. Both the H 2 concentration and H 2 yield reached maximum values of 73.93 vol.% and 84.72 mg g −1 plastic, respectively, as the ratio of Ni:Fe at 1:3. The amount and quality of CNTs were greatly influenced by the catalyst composition, and Ni and Fe display different roles to the overall reactivity of Ni-Fe catalyst for the pyrolysis-catalysis of waste plastics. Catalyst with more Fe loading produced more hydrogen and deposited carbon, due to higher cracking ability and the relatively lower interaction between active sites and support. The presence of Ni in Ni-Fe bimetallic catalyst enhanced the thermal stability and graphitization degree of produced carbons. The thermal quality of filamentous carbons might be associated with carbon defects. [ABSTRACT FROM AUTHOR]

Hydrogen production from the thermochemical conversion of biomass was carried out with nano-sized NiZnAlOx catalysts using a two-stage fixed bed reactor system. The gases derived from the pyrolysis of wood sawdust in the first stage were catalytically steam reformed in the second stage. The NiZnAlOx catalysts were synthesized by a co-precipitation method with different Ni molar fractions (5, 10, 15, 25 and 35%) and a constant Zn:Al molar ratio of 1:4. The catalysts were characterized by a wide range of techniques, including N 2 adsorption, SEM, XRD, TEM and temperature-programmed oxidation (TPO) and reduction (TPR). Fine metal particles of size around 10–11 nm were obtained and the catalysts had high stability characteristics, which improved the dispersion of active centers during the reaction and promoted the performance of the catalysts. The yield of gas was increased from 49.3 to 74.8 wt.%, and the volumetric concentration of hydrogen was increased from 34.7 to 48.1 vol.%, when the amount of Ni loading was increased from 5 to 35%. Meanwhile, the CH 4 fraction decreased from 10.2 to 0.2 vol.% and the C 2 –C 4 fraction was reduced from 2.4 vol.% to 0.0 vol.%. During the reaction, the crystal size of all catalysts was successfully maintained at around 10–11 nm with lowered catalyst coke formation, (particularly for the 35NiZn4Al catalyst where negligible coke was found) and additionally no obvious catalyst sintering was detected. The efficient production of hydrogen from the thermochemical conversion of renewable biomass indicates that it is a promising sustainable route to generate hydrogen from biomass using the NiZnAl metal oxide catalyst prepared in this work via a two-stage reaction system. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) contains significant amounts of polyvinyl chloride (PVC). The reactivity of PVC may form polycyclic aromatic hydrocarbons (PAHs) during the pyrolysis of MSW, which can become a key challenge during the development of pyrolysis technologies. However, there is very limited work in relation to the influence of pyrolysis process conditions in terms of temperature and heating rate on PAHs formation during pyrolysis of PVC. In this work, the formation of 2–4-ring PAHs from the pyrolysis of PVC at temperatures of 500, 600, 700, 800, or 900 °C and at fast and slow heating rates was investigated under a N 2 atmosphere in a fixed bed reactor. With the increase of temperature from 500 to 900 °C, HCl yield decreased from 54.7 to 30.2 wt.%, while the yields of gases and PAHs in the tar increased. Slow pyrolysis generated higher HCl yield, and lower gas and tar yield than fast pyrolysis; the PAH yield obtained from the slow pyrolysis was much lower compared to fast pyrolysis. The results suggest that for fast pyrolysis, the dehydrochlorination of the PVC might be incomplete, resulting in the formation of chlorinated aromatic compounds. [ABSTRACT FROM AUTHOR]

The production of hydrogen-enriched syngas from the thermo-chemical conversion of biomass was studied using Ni/CaAlO x catalysts prepared by co-precipitation method. The effect of Ca addition with different molar ratios of Ca:Al (1:3, 1:2, 1:1, 2:1, 3:1) on the properties and catalytic behavior in relation to syngas production and the coke formation on the surface of the catalysts were investigated. Catalysts were characterized by BET, XRD, TPR, SEM, and TEM. The SEM and TEM results showed that rod-shaped nano-particles were highly dispersed on the surface of the catalyst. The particle size of NiO was slightly affected with the increase of Ca content in the catalyst. It appeared that the selectivity of CO was increased and the selectivity of CO 2 was reduced with the increase of Ca addition to the catalyst. For example, CO 2 concentration was reduced from 20 to 12 vol.%, when the molar ratio of Ca/Al was increased from 1:3 to 3:1 for the Ni/CaAlO x catalyst; it is suggested that the water gas shift reaction was inhibited and CO 2 reforming reactions were promoted in the presence of the catalyst with higher Ca content. The CO/H 2 molar ratio could be manipulated by changing the Ca content in the catalyst, while the H 2 concentration remained almost constant (around 45 vol.%). Thus, using the Ni/CaAlO x catalyst developed in this work could provide a promising route to control the syngas composition, which is an important factor for syngas applications. [ABSTRACT FROM AUTHOR]

Nickel, iron, cobalt and copper catalysts were prepared by impregnation and used to produce carbon nanotubes and hydrogen gas from a LDPE feedstock. A two stage catalytic pyrolysis process was used to enable large yields of both products. Plastics samples were pyrolysed in nitrogen at 600 °C, before the evolved gases were passed to a second stage and allowed to deposit carbon onto the catalyst at a temperature of 800 °C. Carbon nanotubes were successfully generated on nickel, iron and cobalt but were barely observed on the copper catalyst. Iron and nickel catalysts gave the largest yield of both hydrogen and carbon nanotubes as a result of metal-support interactions which were neither too strong, like cobalts, nor too weak like copper. These metal support interactions proved a key factor in CNT production. A nickel catalyst with a weaker interaction was prepared using a lower calcination temperature. Yields of both carbon nanotubes and hydrogen gas were lower on the Ni-catalyst prepared at the lower calcination temperature, as a result of sintering of the nickel particles. In addition, the catalyst prepared at a lower calcination temperature produced metal particles which were too large for CNT growth, producing amorphous carbons which deactivate the catalyst instead. Overall the iron catalyst gave the largest yield of CNTs, which is attributed to both its good metal-support interactions and irons large carbon solubility. [ABSTRACT FROM AUTHOR]

Thermal–chemical processing of biomass is expected to provide renewable and clean energy and fuels in the future. Due to the nature of endothermic reactions, microwave and conventional heating have been applied to this technology. However, more studies need to be carried out to clarify the difference between these two heating technologies. In this work, we investigated two bio-char samples produced from conventional pyrolysis of wood biomass (yield of bio-char: 38.48 and 59.70 wt.%, respectively) and one bio-char produced from microwave pyrolysis with a yield of 45.16 wt.% from the same biomass sample at different process conditions. Various methodologies have been used to characterise the bio-chars. CO 2 gasification of bio-char has also been studied using a thermogravimetric analyser (TGA) and a fixed-bed reaction system. The results show that volatile and carbon contents of the bio-char derived from microwave pyrolysis were between the two conventional bio-chars. However, the microwave bio-char is more reactive for CO 2 gasification, as more CO was released during TGA experiments, and the CO release peak was narrower compared with the CO 2 gasification of the conventional bio-chars. It is suggested that the conventional bio-char is less reactive due to the presence of more secondary chars which are produced from secondary reactions of volatiles during the conventional biomass pyrolysis. While the microwave pyrolysis generates more uniform bio-chars with less secondary char, and therefore, has advantages of producing bio-char for downstream char gasification. [ABSTRACT FROM AUTHOR]

Thermo-chemical processing of biomass is a promising alternative to produce renewable hydrogen as a clean fuel or renewable syngas for a sustainable chemical industry. However, the fast deactivation of catalysts due to coke formation and sintering limits the application of catalytic thermo-chemical processing in the emerging bio-refining industry. In this research, Fe–Zn/Al 2 O 3 nanocatalysts have been prepared for the production of hydrogen through pyrolysis catalytic reforming of wood sawdust. Through characterization, it was found that Fe and Zn were well distributed on the surface with a narrow particle size. During the reactions, the yield of hydrogen increased with the increase of Zn content, as Zn is an efficient metal promoter for enhancing the performance of the Fe active site in the reaction. The 20% Fe/Al 2 O 3 catalyst with Zn/Al ratio of 1:1 showed the best performance in the process in relation to the hydrogen production and resistance to coke formation on the surface of the reacted catalyst. All the catalysts showed ultra-high stability during the process and nearly no sintering were observed on the used catalysts. Therefore, the nanocatalysts prepared in this work from natural-abundant and low-cost metals have promising catalytic properties (high metal dispersion and stability) to produce H 2 -rich syngas with optimal H 2 /CO ratio from the thermo-chemical processing of biomass. [ABSTRACT FROM AUTHOR]

Carbon nanotubes have been produced from a low density polyethylene (LDPE) feedstock via a two stage pyrolysis process. The temperature of the second stage, where carbon deposition on an iron alumina catalyst occurs (growth temperature), was varied using catalyst temperatures of 700, 800 and 900 °C. An increase in catalyst temperature led to a higher yield of both carbon nanotubes and hydrogen, as the rate of carbon deposition increased. Changing the amount of feedstock relative to the catalyst also had an effect on the production of both carbon nanotubes and hydrogen. As more feedstock is used a larger source of carbon gives rise to a larger amount of carbon nanotubes per gram of catalyst. However, in terms of the percentage of feedstock converted into carbon nanotubes and hydrogen gas, a reduction was observed. Conversion of plastic into carbon nanotubes was 29.1 wt.% when 0.5 g LDPE was used, but reduced to 13.1 wt.% with 1.25 g LDPE. This is because the catalyst activity reduces as it becomes overloaded, and much of the hydrocarbon gases are left unreacted. This gives an economic playoff between large conversion of plastics into carbon nanotubes and hydrogen gas, and large yields of carbon nanotubes per gram of catalyst used. [ABSTRACT FROM AUTHOR]

The formation of 2–4 ring polycyclic aromatic hydrocarbons (PAH) from the pyrolysis of nine different municipal solid waste fractions (xylan, cellulose, lignin, pectin, starch, polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET)) were investigated in a fixed bed furnace at 800 °C. The mass distribution of pyrolysis was also reported. The results showed that PS generated the most total PAH, followed by PVC, PET, and lignin. More PAH were detected from the pyrolysis of plastics than the pyrolysis of biomass. In the biomass group, lignin generated more PAH than others. Naphthalene was the most abundant PAH, and the amount of 1-methynaphthalene and 2-methynaphthalene was also notable. Phenanthrene and fluorene were the most abundant 3-ring PAH, while benzo[ a ]anthracene and chrysene were notable in the tar of PS, PVC, and PET. 2-ring PAH dominated all tar samples, and varied from 40 wt.% to 70 wt.%. For PS, PET and lignin, PAH may be generated directly from the aromatic structure of the feedstock. [ABSTRACT FROM AUTHOR]

This paper investigates the co-production of hydrogen and carbon nanotubes from the pyrolysis–catalytic gasification of waste plastics (polypropylene). We report on the influence of a range of metal additions to a nickel based catalyst based on ternary mixed oxide types Ni–Metal–Al, where the metal was Zn, Mg, Ca, Ce or Mn. The results showed that of the different metal–nickel catalysts investigated, the Ni–Mn–Al catalyst was the most promising catalyst in relation to the co-production of hydrogen and CNT. For example, the Ni–Mn–Al catalyst produced 71.4 mmol hydrogen g − 1 plastic, while the hydrogen production using Ni–Ca–Al, Ni–Ce–Al and Ni–Zn–Al catalysts were 68.5 mmol g − 1 , 63.1 mmol g − 1 and 45.9 mmol hydrogen g − 1 plastic respectively. In addition, carbon deposition on the catalyst was highest in the order of: Ni–Mn–Al > Ni–Ca–Al > Ni–Zn–Al > Ni–Ce–Al > Ni–Mg–Al. The carbon deposition for the Ni–Mn–Al catalyst was found to consist of mostly carbon nanotubes. Further investigation of the Ni–Mn–Al catalyst demonstrated that the interaction between Ni and catalyst support plays a significant role in the gasification process; weak metal support interaction (for the Ni–Mn–Al catalyst calcined at 300 °C) resulted in a lower hydrogen production and much higher yield of carbon products. In addition, the influence of steam injection rate on hydrogen and carbon nanotube production was investigated for the Ni–Mn–Al catalyst. Increasing the steam injection rate significantly increased hydrogen production and decreased carbon deposition. However, at lower steam injection rates, the quality of the product carbon nanotubes was improved. [ABSTRACT FROM AUTHOR]

The interactions of biomass constituents (hemicellulose, cellulose and lignin) were investigated during fast pyrolysis at 800 °C in a fixed bed reactor. The formation of polycyclic aromatic hydrocarbons (PAH) as well as mass distribution and gas products is presented. The possible interactions of biomass constituents were compared with the results of the expected results based on the pyrolysis of single components. For the interaction of xylan and cellulose, the mass distribution was similar to that expected from calculation of single component addition, however, PAH were increased. The interaction of xylan and lignin produced a decrease in PAH concentration compared to that expected from single component data. There was evidence of strong interaction between cellulose and lignin, where gas and solid residue yield was decreased and tar/oil yield was increased. In addition, naphthalene, acenaphthylene, and chrysene/benzo[ a ]anthracene were decreased compared with the concentrations expected from the single component pyrolysis. However, the amounts of 1-methynaphthalene, 2-methynaphthalene, acenaphthene, fluorene, phenanthrene, anthracene, and pyrene were increased. [ABSTRACT FROM AUTHOR]

Hydrogen production from renewable resources has received extensive attention recently for a sustainable and renewable future. In this study, hydrogen was produced from catalytic steam reforming of the aqueous fraction of crude bio-oil, which was obtained from pyrolysis of biomass. Five Ni–Al catalysts modified with Ca, Ce, Mg, Mn and Zn were investigated using a fixed-bed reactor. Optimized process conditions were obtained with a steam reforming temperature of 800 °C and a steam to carbon ratio of 3.54. The life time of the catalysts in terms of stability of hydrogen production and prohibition of coke formation on the surface of the catalyst were carried out with continuous feeding of raw materials for 4 h. The results showed that the Ni–Mg–Al catalyst exhibited the highest stability of hydrogen production (56.46%) among the studied catalysts. In addition, the life-time test of catalytic experiments showed that all the catalysts suffered deactivation at the beginning of the experiment (reduction of hydrogen production), except for the Ni–Mg–Al catalyst; it is suggested that the observation of abundant amorphous carbon formed on the surface of reacted catalysts (temperature programmed oxidation results) may be responsible for the initial reduction of hydrogen production. In addition, the Ni–Ca–Al catalyst showed the lowest hydrogen production (46.58%) at both the early and stabilized stage of catalytic steam reforming of bio-oil. [ABSTRACT FROM AUTHOR]

Highlights: [•] Conventional and microwave pyrolysis of biomass has been compared. [•] Conventional pyrolysis produces higher gas yield. [•] Microwave pyrolysis produces more char. [•] Two stages of gas release are seen, first CO & CO2 and second CH4 & H2. [Copyright &y& Elsevier]

Hydrogen production from the pyrolysis/reforming of refuse derived fuel (RDF) was investigated with a series of Ni/SiO2 catalysts. The catalysts were prepared by homogeneous precipitation derived from a sol–gel method (HPG) and compared to Ni/SiO2 catalysts prepared by adding a phase separation step to the HPG process (B-HPG). All the catalysts had a NiO loading of 10 wt.%, and three different calcination temperatures (500 °C, 700 °C and 900 °C) were used for each method. The prepared Ni/SiO2 catalysts were analysed to determine their surface area, and porosity characteristics; additionally scanning electron microscopy (SEM-EDX), transmission electron microscopy (TEM), infrared spectroscopy (FTIR), and X-Ray diffraction (XRD) analyses were carried out. The results showed that the catalyst prepared by HPG and calcined at 700 °C (HPG700), presented a relatively high surface area (∼347 m2 g−1), large pore diameter (12.50 nm), and also resulted in the highest catalytic activity towards H2 production, attaining ∼60 vol.% hydrogen. The lowest hydrogen concentration of about 42 vol.% was obtained using the catalysts prepared by the combined HPG-phase separation method, and calcined at 900 °C (B-HPG900). It was also observed that at calcination temperatures higher than 700 °C the catalytic activity for hydrogen production was diminished for both preparation methods. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two-stage pyrolysis-gasification of plastics can produce H2 and carbon nanotubes. [•] Carbon nanotube quality or H2 yield can be optimised by control of steam content. [•] Therefore, wastes can be processed for environmental and economic benefit. [Copyright &y& Elsevier]

In this report, we introduce a novel and commercially viable method to recover renewable hydrogen and carbon nanotubes from waste glycerol produced in the biodiesel process. Gas-phase catalytic reforming converts glycerol to clean hydrogen fuel and by replacing the problematical coke formed on the catalyst with high value carbon nanotubes, added value can be realised. Additional benefits of around 2.8 kg CNTs from the reforming of 1 tonne of glycerol and the production of 500 Nm3H2 could have a considerable impact on the economics of glycerol utilization. Thereby, the contribution of this research will be a significant step forward in solving a current major technical and economic challenge faced by the biofuels industry [ABSTRACT FROM AUTHOR]

Abstract: Catalytic steam reforming of liquid hydrocarbons is one of the promising alternatives for hydrogen production. However, coke deposition on the reacted catalyst results in catalyst deactivation and also CO2 emission during reforming are among the main challenges in the process. In this work, the production of high-value carbon nanotubes (CNTs) during hydrogen production from catalytic reforming of toluene has been investigated. Thus, less carbon emission and higher product values can be expected from the process. A two-stage fixed bed pyrolysis-reforming reactor was used in this work. The results showed that the addition of a Ni–Mg–Al catalyst, with an additional downstream stainless steel mesh, increased hydrogen production from 24.8 to 54.8 (mmol H2 g−1 toluene), when water (steam) was injected at a rate of 0.01 g min−1. CNTs were also produced in the process in the presence of the Ni–Mg–Al catalyst and with a water injection rate of 0.01 g min−1 had the highest band ratio of G′/G when analyzed by Raman spectrometry, indicating the highest purity of CNTs. In addition, Raman spectra of the generated CNTs showed that the purity of CNTs was reduced with the addition of water for reforming without the Ni–Mg–Al catalyst. The presence of the Ni–Mg–Al catalyst significantly increased the yield of CNTs formed on the surface of the stainless steel mesh and also improved the quality of the CNTs in relation to the distribution of diameters and their length. [Copyright &y& Elsevier]

Abstract: A series of Ni/SiO2 catalysts have been prepared and investigated for their suitability for hydrogen production and tar reduction in a two-stage pyrolysis-reforming system, using refuse derived fuel (RDF) as the raw material. Experiments were conducted at a pyrolysis temperature of 600°C, and a reforming temperature of 800°C. The product gases were analysed by gas chromatography (GC) and the condensed fraction was collected and quantified using gas chromatography-mass spectrometry (GC–MS). The effects of the catalyst preparation method, nickel content and the addition of metal promoters (Ce, Mg, Al), were investigated. Catalysts were characterised using BET surface area analysis, temperature programmed oxidation (TPO), and scanning electron microscopy (SEM). The TPO and SEM analysis of the reacted catalysts showed that amorphous type carbons tended to be deposited over the Ni/SiO2 catalysts prepared by impregnation, while filamentous type carbons were favoured with the sol-gel prepared catalysts. The influence of catalyst promoters (Ce, Mg, Al) added to the Ni/SiO2 catalyst prepared by the sol-gel method was found not to be significant, as the H2 production was not increased and the tar formation was not reduced with the metal-added catalyst. The highest H2 concentration of 57.9vol.% and lower tar amount produced of 0.24mgtar/gRDF; were obtained using the 20wt.% Ni/SiO2 catalyst prepared by sol-gel. On the other hand a low catalytic activity for H2 production and higher tar produced were found for the impregnated series of catalysts, which might be due to the smaller surface area, pore size and due to the formation of amorphous carbons on the catalyst surface. Alkenes and alcohol functional groups were mainly found in the analysed tar samples, with major concentrations of styrene, phenol, indene, cresols, naphthalene, fluorene, and phenanthrene. [Copyright &y& Elsevier]

Abstract: Cellulose, hemicellulose and lignin are the main components of biomass. This work presents research into the pyrolysis/gasification of all three main components of biomass, in order to evaluate and compare their hydrogen production and also understand their gasification processes. A fixed bed, two-stage reaction system has been used employing various nickel-based catalysts. Gas concentration (CO, H2, CO, CO2 and CH4) was analysed for the produced non-condensed gases. Oil byproducts were analysed by gas chromatography/mass spectrometry (GC/MS). Various techniques such as X-Ray Diffraction (XRD), scanning electron microscopy (SEM) coupled to an energy dispersive X-ray spectroscopy (EDXS), temperature-programmed oxidation (TPO) were applied to characterize the fresh or reacted catalysts. The experimental results show that the lignin sample generates the highest residue fraction (52.0wt.%) among the three biomass components. When Niph name="sbnd" />Al (1:1) catalyst was used in the gasification process, gas yield was increased from 62.4 to 68.2wt.% for cellulose, and from 25.2 to 50.0wt.% for the pyrolysis/gasification of lignin. Hydrogen production was increased from 7.0 to 18.7 (mmolg−1 sample) when the Niph name="sbnd" />Al (1:1) catalyst was introduced in the pyrolysis/gasification of cellulose. Among the investigated catalysts, Niph name="sbnd" />Al (1:1) was found to be the most effective for hydrogen production from cellulose pyrolysis/gasification. [Copyright &y& Elsevier]

Abstract: Hydrogen and syngas production have been investigated from the pyrolysis/gasification of biomass components (cellulose, xylan and lignin) in the presence of Ni-based catalysts by using a two-stage fixed-bed reaction system. Biomass samples were pyrolysed at the first stage and the derived products were gasified at the second stage. The Ni–Mg–Al and Ni–Ca–Al catalysts, prepared by co-precipitation, were applied in the gasification process. The lignin sample pyrolysed with more difficulty (56.0wt.% of residue fraction) compared with cellulose and xylan at 500°C, and therefore resulted in the lowest gas yield (42.7wt.%) for the pyrolysis/gasification of lignin. However, the highest H2 concentration from the three types of feedstock (55.1vol.%) was collected for the lignin sample in the presence of steam and catalyst. Carbon deposition was very low as indicated from the TPO and SEM analyses of the reacted Ni–Mg–Al catalyst. The investigation of reaction conditions showed that water injection rate (0.02 and 0.05gmin−1) had little influence on the gas production from the pyrolysis/gasification of lignin in the presence of the Ni–Ca–Al catalyst; however, the increase of gasification temperature from 700 to 900°C resulted in a higher gas and hydrogen production due to the promotion of secondary reactions during the gasification process. Furthermore, coking was highest for the reacted Ni–Ca–Al catalyst at the gasification temperature of 800°C (7.27wt.%), when the temperature was increased from 700 to 900°C. This work shows that the components of biomass have a significant influence on the catalytic gasification process related to hydrogen and syngas production. [Copyright &y& Elsevier]

Abstract: A two-stage continuous screw-kiln reactor was investigated for the production of synthesis gas (syngas) from the pyrolysis of biomass in the form of waste wood and subsequent catalytic steam reforming of the pyrolysis oils and gases. Four nickel based catalysts; NiO/Al2O3, NiO/CeO2/Al2O3, NiO/SiO2 (prepared by an incipient wetness method) and another NiO/SiO2 (prepared by a sol–gel method), were synthesized and used in the catalytic steam reforming process. Pyrolysis of the biomass at a rapid heating rate of approximately 40°C/s, was carried out at a pyrolysis temperature of 500°C and the second stage reforming of the evolved pyrolysis gases was carried out with a catalytic bed kept at a temperature of 760°C. Gases were analysed using gas chromatography while the fresh and reacted catalyst was analysed by scanning electron microscopy, thermogravimetric analysis, transmission electron microscopy with energy dispersive X-ray and X-ray photoelectron spectroscopy. The reactor design was shown to be effective for the pyrolysis and catalytic steam reforming of biomass with a maximum syngas yield of 54.0wt.% produced when the sol–gel prepared NiO/SiO2 catalyst was used, which had the highest surface area of 765m2 g−1. The maximum H2 production of 44.4vol.% was obtained when the NiO/Al2O3 catalyst was used. [Copyright &y& Elsevier]

Abstract: Pyrolysis of waste materials, biomass wood waste, waste tyre, refuse derived fuel (RDF) and waste plastic was performed using two thermogravimetric analysers (TGA). One TGA was coupled to a mass spectrometer (MS) and the other to an infrared spectrometer (FTIR). The kinetic parameters of the pyrolysed waste materials obtained for TGA-MS and TGA-FTIR were compared using a model based on first-order reactions with a distribution of the activation energies. A further comparison of the volatile species evolved by thermal degradation (TGA) and the subsequent characterisation by the MS and FTIR spectra was performed. The first-order reaction pathways and subsequent activation energies calculated from the differential TGA data presented good repeatability between the TGA-MS and TGA-FTIR. The TGA-MS and TGA-FTIR produced a broad spectrum of qualitative data characterising the volatile gaseous fraction of the waste materials pyrolysed. TGA-MS and TGA-FTIR are shown to be valuable techniques in corroborating the respective thermograms and spectrograms of the volatile species evolved during the pyrolysis of waste materials. However both techniques are prone to interference and careful interpretation of the spectra produced is required. [Copyright &y& Elsevier]

Abstract: The steam pyrolysis-gasification of biomass, wood sawdust, was carried out with a Ni/MCM-41 catalyst for hydrogen production in a two-stage fixed bed reaction system. The wood sawdust was pyrolysed in the first reactor and the derived products were gasified in the second reactor. The synthesised MCM-41 mesoporous catalyst supports were impregnated with different Ni loadings (5, 10, 20 and 40wt.%), which were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature programmed reduction (TPR), transmission electron microscopy (TEM) and temperature-programmed oxidation (TPO). NiO particles were homogeneously dispersed inside the pores of 5, 10, and 20wt.% Ni/MCM-41 catalysts; however, more bulkly NiO particles (up to 200nm particle size) were detected outside the pores with an increase of the Ni loading up to 40wt.%. Gas production was increased from 40.7 to 62.8wt.%, hydrogen production was increased from 30.1 to 50.6vol.% of total gas composition when the Ni loading was increased from 5 to 40wt.% during the pyrolysis-gasification of wood sawdust. This work showed low coke deposition (from 0.5 to 4.0wt.%) with valuable bio-oil by-products using the Ni/MCM-41 catalyst. The highly efficient conversion of renewable biomass resource to hydrogen and bio-oil with very low coke deposition indicates that biomass gasification on Ni/MCM-41 catalysts via two-stage reaction is a promising method for the development of the biorefinery concept. [Copyright &y& Elsevier]

Abstract: Hydrogen production from the pyrolysis–gasification of waste tyres has been investigated with a Ni/CeO2/Al2O3 catalyst using a two-stage fixed bed reaction system. The conditions of catalyst preparation such as Ni and CeO2 content and calcination temperature were investigated in relation to product yield and composition. The fresh and reacted catalysts were analysed using thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The results showed that there were small changes in the gas and hydrogen yield by adding 5 wt.% of CeO2 into the Ni/CeO2/Al2O3 catalyst. The gas yield related to the mass of waste tyre and the amount of reacted water were increased with the increase of CeO2 content from 5 to 15 wt.%. However, with the further increase of CeO2 content to 30 wt.%, the gas yield related to the mass of tyre and the amount of reacted water was reduced. Increasing the Ni content of the catalyst showed a positive influence on the gas yield and hydrogen production. The investigation of the calcination temperature of the Ni/CeO2/Al2O3 catalyst showed that the oil yield related to the mass of tyre and reacted water decreased from 28.4 to 23.4 wt.% for the catalyst calcined at 500 °C, and decreased from 24.2 to 17.7 wt.% for the catalyst calcined at 750 °C. When the Ni content of the catalyst was increased from 5 to 20 wt.%. there were only small changes in total gas and hydrogen production from the pyrolysis–gasification of waste tyre. Lower coke deposition on the reacted catalyst was obtained for the Ni/CeO2/Al2O3 catalyst prepared at the calcination temperature of 750 °C compared with the 500 °C calcination temperature. [Copyright &y& Elsevier]

Abstract: Steam reforming of ethanol to produce hydrogen was carried out using a two-stage reaction system with several nano-Ni/SiO2 catalysts prepared at different citric acid (CA) contents using the sol–gel process. The fresh (non-calcined and calcined) catalysts and the reacted catalysts were analysed using surface area and pore size analysis, Fourier-transform infrared (FTIR) spectroscopy, thermo-gravimetry analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that a meso-structured material was produced at Ni:CA ratios lower than 1:0.5; and the pore volume of the catalyst was increased when more citric acid was used during the sol–gel preparation. Gas and hydrogen yield were observed to be increased when the Ni:CA ratio was reduced from 1:0.5 to 1:3.0; however, gas concentration was slightly changed for the catalysts prepared at different Ni:CA ratios. In addition, coke formation was increased from 0.7 to 7.5wt.% when the Ni:CA ratio decreased from 1:0.5 to 1:3.0. It was also found that the Ni/SiO2 catalyst prepared at the low CA content (Ni:CA=0.5) was non-stable during the ethanol steam reforming process; since sintering was obtained as observed using TEM analysis of the used catalyst. [ABSTRACT FROM AUTHOR]

Abstract: Polypropylene, polystyrene, high density polyethylene and their mixtures and real-world plastic waste were investigated for the production of hydrogen in a two-stage pyrolysis–gasification reactor. The experiments were carried out at gasification temperatures of 800 or 850°C with or without a Ni–Mg–Al catalyst. The influence of plastic type on the product distribution and hydrogen production in relation to process conditions were investigated. The reacted Ni–Mg–Al catalysts were analyzed by temperature-programmed oxidation and scanning electron microscopy. The results showed that lower gas yield (11.2 wt.% related to the mass of plastic) was obtained for the non-catalytic non-steam pyrolysis–gasification of polystyrene at the gasification temperature of 800°C, compared with the polypropylene (59.6 wt.%) and high density polyethylene (53.5 wt.%) and waste plastic (45.5 wt.%). In addition, the largest oil product was observed for the non-catalytic pyrolysis–gasification of polystyrene. The presence of the Ni–Mg–Al catalyst greatly improved the steam pyrolysis–gasification of plastics for hydrogen production. The steam catalytic pyrolysis–gasification of polystyrene presented the lowest hydrogen production of 0.155 and 0.196 (g H2/g polystyrene) at the gasification temperatures of 800 and 850°C, respectively. More coke was deposited on the catalyst for the pyrolysis–gasification of polypropylene and waste plastic compared with steam catalytic pyrolysis–gasification of polystyrene and high density polyethylene. Filamentous carbons were observed for the used Ni–Mg–Al catalysts from the pyrolysis–gasification of polypropylene, high density polyethylene, waste plastic and mixed plastics. However, the formation of filamentous carbons on the coked catalyst from the pyrolysis–gasification of polystyrene was low. [Copyright &y& Elsevier]

Abstract: A novel Ni–Mg–Al–CaO catalyst/sorbent has been prepared by integration of the catalytic and CO2 absorbing properties of the material to maximise the production of hydrogen. The prepared catalyst was tested for hydrogen production from the pyrolysis–gasification of polypropylene by using a two-stage fixed-bed reaction system. X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM)-energy dispersive X-ray spectrometry (EDXS) were used to characterize the prepared Ni–Mg–Al–CaO catalyst/sorbent. Ni–Mg–Al–CaO and calcined dolomite showed a stable carbonation conversion after several cycles of carbonation/calcination, while CaO showed a certain degree of decay. The calcined dolomite showed low efficiency for hydrogen production from pyrolysis–gasification of polypropylene. Increasing the gasification temperature resulted in a decrease of H2/CO ratio for the Ni–Mg–Al catalyst mixed with sand; however, a stable H2/CO ratio (around 3.0) was obtained for the Ni–Mg–Al–CaO catalyst. An increased Ni–Mg–Al–CaO catalyst/polypropylene ratio promoted the production of hydrogen from the pyrolysis–gasification of polypropylene. Approximately 70wt.% of the potential H2 production was obtained, when the Ni–Mg–Al–CaO catalyst/polypropylene ratio and gasification temperature were 5 and 800°C, respectively. [Copyright &y& Elsevier]

Abstract: Co-precipitated Ni-Mg-Al catalyst was prepared and investigated in relation to the production of hydrogen from the catalytic steam pyrolysis-gasification of polypropylene using a two-stage reaction system. Coke formation on the Ni-Mg-Al catalyst was investigated by using temperature-programmed oxidation (TPO), X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDXS), transmission electron microscopy (TEM) and focused ion beam (FIB)/scanning electron microscopy (SEM). The coke formation mechanism on the Ni-Mg-Al catalyst is proposed. It is suggested that the Ni-Mg-Al catalyst is initially reduced during the gasification process, the reactions of decomposition/reforming of hydrocarbons gases occur on the surface and inside the catalyst; this resulted in partial fragmentation of the catalyst into small particles. Layered carbons, perhaps containing monoatomic carbon, metal carbides, etc., are suggested to be a transition layer for the formation of filamentous carbons. The addition of Mg into the Ni-Al catalyst was found to increase the catalytic activity and the physical stability of catalyst. In addition, increasing the calcination temperature from 750 to 850°C reduced the surface area of the fresh Ni-Mg-Al catalyst, increased the NiO crystal size, and resulted in a decrease of catalytic activity in the pyrolysis-gasification of polypropylene; however, a more stable catalyst was obtained with higher calcination temperature. [Copyright &y& Elsevier]

Abstract: Post-consumer plastic waste derived from municipal solid waste was investigated using a two-stage, catalytic steam pyrolysis–gasification process for the production of hydrogen. The three important process parameters of catalyst:plastic ratio, gasification temperature and water injection rate were investigated. Temperature-programmed oxidation (TPO) and scanning electron microscopy (SEM) methods were used to analyse the reacted catalysts. The results showed that there was little influence of catalyst:plastic ratio between the range 0.5 and 2.0(g/g) on the mass balance and gas composition for the pyrolysis–gasification of waste plastics; this might be due to the effective catalytic activity of the Ni–Mg–Al catalyst. However, increasing the gasification temperature and the water injection rate resulted in an increase of total gas yield and hydrogen production. The coke formation on the catalyst was reduced with increasing use of catalyst; however, a maximum coke formation (9.6wt.%) was obtained at the gasification temperature of 700°C when the influence of gasification temperature was investigated. The maximum coke formation was obtained at the water injection rate of 4.74gh−1, and a more reactive form of coke seemed to be formed on the catalyst with an increase of the water injection rate, according to the TPO experiments. [Copyright &y& Elsevier]

Abstract: The production of hydrogen from the two-stage pyrolysis–gasification of polypropylene using a Ni/CeO2/ZSM-5 catalyst has been investigated. Experiments were conducted on CeO2 loading, calcination temperature and Ni loading of the Ni/CeO2/ZSM-5 catalyst in relation to hydrogen production. The results indicated that with increasing CeO2 loading from 5 to 30wt.% for the 10wt.% Ni/CeO2/ZSM-5 catalyst calcined at 750°C, hydrogen concentration in the gas product and the theoretical potential hydrogen production were decreased from 63.0 to 49.8vol.% and 50.4 to 21.6wt.%, respectively. In addition, the amount of coke deposited on the catalyst was reduced from 9.5 to 6.2wt.%. The calcination temperature had little influence on hydrogen production for the catalyst containing 5wt.% of CeO2. However, for the 10wt.% Ni/CeO2/ZSM-5 catalyst with a CeO2 content of 10 or 30wt.%, the catalytic activities reduced when the calcination temperature was increased from 500 to 750°C. The SEM results showed that large amounts of filamentous carbons were formed on the surface of the catalysts. The investigation of different Ni content indicates that the Ni/CeO2/ZSM-5 ((2-10)-5-500) catalyst containing 2wt.% Ni showed poor catalytic activity in relation to the pyrolysis–gasification of polypropylene according to the theoretical potential H2 production (7.2wt.%). Increasing the Ni loading to 5 or 10wt.% in the Ni/CeO2/ZSM-5 ((2-10)-5-500) catalyst, high potential hydrogen production was obtained. [Copyright &y& Elsevier]

Abstract: Co-precipitated nickel-based catalysts with different metallic molar ratios and calcination temperature were investigated for the production of hydrogen from the pyrolysis–gasification of polypropylene. The experiments were carried out at a pyrolysis temperature of 500°C and gasification temperature of 800°C in the presence of steam using a two-stage reaction system. The results suggest that with increasing Ni content in the Ni-Al or Ni-Mg-Al catalyst, the catalytic activity of the catalyst increased, in relation to hydrogen production. For example, the potential hydrogen production increased from 48.8 to 57.7wt.%, and the amount of water reacted increased from 1.2 to 1.3 (g water/g polypropylene), when the Ni-Al molar ratio was increased from 1:4 to 1:1. After reaction in the pyrolysis–gasification process, the non-reduced Ni-Al catalyst was reduced into metallic Ni, as observed from XRD and TGA analysis. The introduction of Mg into the Ni-Al catalyst significantly increased the amount of reacted water and improved the performance of the catalyst in relation to coke formation, although the hydrogen production was not significantly improved. For the Ni-Al or Ni-Mg-Al catalyst, a 850°C calcination temperature resulted in a lower catalytic activity compared to the lower calcination temperature of 750°C. The substitution of Cu for Mg in the Ni-Mg-Al catalyst significantly reduced the catalytic ability for hydrogen production. [Copyright &y& Elsevier]

Abstract: Several nickel-based catalysts (Ni/Al2O3, Ni/MgO, Ni/CeO2, Ni/ZSM-5, Ni-Al, Ni-Mg-Al and Ni/CeO2/Al2O3) have been prepared and investigated for their suitability for the production of hydrogen from the two-stage pyrolysis–gasification of polypropylene. Experiments were conducted at a pyrolysis temperature of 500°C and gasification temperature was kept constant at 800°C with a catalyst/polypropylene ratio of 0.5. Fresh and reacted catalysts were characterized using a variety of methods, including, thermogravimetric analysis, scanning electron microscopy with energy dispersive X-ray spectrometry and transmission electron microscopy. The results showed that Ni/Al2O3 was deactivated by two types of carbons (monoatomic carbons and filamentous carbons) with a total coke deposition of 11.2wt.% after reaction, although it showed to be an effective catalyst for the production of hydrogen with a production of 26.7wt.% of the theoretical yield of hydrogen from that available in the polypropylene. The Ni/MgO catalyst showed low catalytic activity for H2 production, which might be due to the formation of monoatomic carbons on the surface of the catalyst, blocking the access of gaseous products to the catalyst. Ni-Al (1:2) and Ni-Mg-Al (1:1:2) catalysts prepared by co-precipitation showed good catalytic abilities in terms of both H2 production and prevention of coke formation. The ZSM-5 zeolite with higher surface area was also shown to be a good support for the nickel-based catalyst, since, the Ni/ZSM-5 catalyst showed a high rate of hydrogen production (44.3wt.% of theoretical) from the pyrolysis–gasification of polypropylene. [Copyright &y& Elsevier]

Abstract: A zeolite catalyst of ultrastable Y-type (USY) was investigated in the research of two staged pyrolysis–catalysis of scrap tyres. Scrap tyres were pyrolysed in a fixed bed reactor and the evolved pyrolysis gases were passed through a secondary catalytic reactor. The main objective of this paper was to investigate the effect of zeolite USY on the yield of products and the composition of derived oil. The influences of several parameters such as pyrolysis temperature, catalytic temperature, catalyst/tyre ratio, heating rate, etc. on the yield of the derived oil, char and gas were investigated. It showed that the increase of catalytic temperature and catalyst/tyre ratio resulted in high yield of gas at the expense of the oil yield. For example, when the catalyst/tyre ratio increased from 0.25 to 1.0, the yield of gas increased from 30.5 to 49.9wt.%, and the oil yield decreased nearly two-fold from 31.6 to 12.7wt.%. The concentration of light naphtha (boiling point<160°C) was also investigated in this study. And the high catalyst/tyre ratio favored to increase the concentration of light naphtha (<160°C) in oil. In order to study the composition of derived oil, a distilled fraction (<280°C), which was 92.5wt.% of the oil obtained from catalytic pyrolysis of scrap tyre at a pyrolysis temperature, catalytic temperature and catalyst/tyre ratio of 500, 400°C and 0.5, respectively, was analyzed with gas chromatography/mass spectrometry (GC/MS). The distillate was found to contain 1.23wt.% benzene, 9.35wt.% toluene, 3.68wt.% ethylbenzene, 12.64wt.% xylenes, 1.81wt.% limonene and 13.89wt.% PAHs, etc., where the single ring aromatics represented a significant potential use as chemicals. [Copyright &y& Elsevier]

[Display omitted] • A valorisation route for sodium lignosulfonate to fabricate electrocatalysts based on N/S- co -doped Ruthenium for HER is showcased. • The effect of S defects on the electronics metal-carbon interactions (EMICs) between Ruthenium and carbon supports is studied in-depth. • The high HER activity tailoring by enhanced EMICs is further revealed by electrochemical testing and density functional theory (DFT) computations. Ruthenium (Ru) nanoparticles dispersed on carbon support are promising electrocatalysts for hydrogen evolution reaction (HER) due to strong electronic metal-carbon interactions (EMCIs). Defects engineering in carbon supports is an effective strategy to adjust EMCIs. We prepared nitrogen/sulfur co-doped carbon supported Ru nanoparticles (Ru@N/S-LC) using sodium lignosulfonate and urea as feedstocks. Intrinsic S dopants from sodium lignosulfonate create rich S defects, thus enhancing the EMCIs within Ru@N/S-LC, leading a faster electron transfer between Ru nanoparticles and N/S-LC compared with N -doped carbon supported Ru nanoparticles (Ru@ N -CC). The resulting Ru@N/S-LC exhibits an enhanced work function and a down-shifted d-band center, inducing stronger electron capturing ability and weaker hydrogen desorption energy than Ru@ N -CC. Ru@N/S-LC requires only 7 and 94 mV overpotential in acidic medium and alkaline medium to achieve a current density of 10 mA cm−2. Density Functional Theory (DFT) calculations were utilized to clarify the impact of sulfur (S) doping and the mechanism underlying the notable catalytic activity of Ru@N/S-LC. This study offers a perspective for utilizing the natural dopants of biomass to adjust the EMCIs for electrocatalysts. [ABSTRACT FROM AUTHOR]

• A hybrid power generation system is analysed. • Energy and Exergy analysis of the co-generation system are performed. • The sub-system components exergy destruction was analysed. • The maximum destroyed exergy arises in the gasifier. • The system has an advantage in terms of its dual stream energy output. A thermodynamic analysis of a power system consisting of adiabatic compressed air energy storage and biomass gasification energy storage power system in a hybrid mode for simultaneous production of electricity and warm water for use domestically is presented in this paper. The hybrid system is designed to meet peak load power demand of 1.3 MW from a blend of 1 MW adiabatic compressed air energy storage system powered by electricity and 0.3 MW rated dual fuel (syngas + diesel) powered engine. The syngas fuel used in the dual fuel engine is supplied by a downdraft biomass gasification system whose wood feed is supplied by a hot air dryer system operated by waste thermal energy recuperated from the system. The performance of the overall system is assessed with total system efficiency, electrical efficiency, effective electrical and exergy efficiency as metrics. In addition, the performance of the sub-components of the system is appraised using exergy destruction and exergy efficiency. The overall energy and exergy efficiency of the system is found to be approximately 38% and 29%, respectively. The electrical and effective electrical efficiency, are 30 and 34%, respectively. The exergy efficiency of the sub-system components are 61.38, 21.47, 5.76, 89.17 and 86.12% for the biomass gasifier, dual fuel engine, hot air dryer, air compressor and air expander, respectively. It is found that the destroyed exergy in the components of the hybrid system is the uppermost in the biomass gasifier, then the DFE and the AE in that order. The minimum destroyed exergy occurs in the hot air dryer. The system has a primary energy savings ratio 10 which means it cannot be deployed as a CHP system under the EU criteria. [ABSTRACT FROM AUTHOR]

• Proof-of-concept of using the Structured ZSM-5/SiC foam catalyst for upgrading bio-oils • Thermal treatment of zeolite precursor affects the quality of supported ZSM-5 coating on SiC foams • Structured ZSM-5/SiC foam catalyst improves the activity and stability of bio-oils upgrading reactions • Deactivation mechanisms of ZSM-5/SiC foam and ZSM-5 pellets catalysts are discussed ZSM-5 zeolite coating supported on SiC foams was prepared by a precursor dispersion-secondary growth method and the resulting structured ZSM-5/SiC foam catalyst was used for the proof-of-concept study of catalytic bio-oils upgrading (i.e. deoxygenation of the model compounds of methanol and anisole) in reference to ZSM-5 catalyst pellets. A layer of ZSM-5 coating with inter-crystal porosity on SiC foams was produced by curing the zeolite precursor thermally at 80 °C. The use of SiC foam as the zeolite support significantly improved transport phenomena compared to the packed-bed using ZSM-5 pellets, explaining the comparatively good catalytic performance achieved by the structured ZSM-5/SiC foam catalyst. In comparison with the ZSM-5 pellets, the ZSM-5/SiC foam catalyst showed 100.0% methanol conversion (at the weight hourly space velocity, WHSV, of 8 h–1) and 100.0% anisole conversion (at WHSV =5 h−1) at the initial stage of the processes, while only about 3% were obtained for the ZSM-5 pellets, under the same conditions. Based on the comparative analysis of the characterisation data on the fresh and spent catalysts, the deactivation mechanisms of the ZSM-5/SiC and the ZSM-5 pellet catalysts were explained. The process intensification using SiC foam to support ZSM-5 improved the global gas-to-solid mass transfer notably, and hence mitigating the pore blocking due to the carbon deposition on the external surface of supported ZSM-5. [ABSTRACT FROM AUTHOR]

Biomass is a low-cost, readily available, widely distributed, environmentally friendly and renewable carbon source. How to realize the reasonable disposal of biomass is an important question because it is a by-product/bio-waste of agriculture, industry and forestry. Carbon nanomaterials (CNMs), especially carbon nanotubes (CNTs), carbon nanofibers (CNFs), and graphene, conventionally prepared from fossil fuels are the most in-demand carbon materials at present due to their outstanding characteristics and extensive applications. The purpose of this review is to overview the progress in the technology of the preparation of CNMs from biomass in the last few decades. The production of these high value-added CNMs from biomass is intensively investigated, together with the applications of biomass as catalysts and catalyst supports during the preparation of CNMs. Finally, the advances in the application of biomass-based CNMs in terms of ecological remediation, photocatalysis, electrode materials for supercapacitors and batteries, chemical catalysis and composites are briefly summarized to develop the potential market of biomass-based CNMs. [ABSTRACT FROM AUTHOR]

The influence of the addition of transition metals involving nickel (Ni), cobalt (Co), iron (Fe) and manganese (Mn) on the thermal behavior and kinetic of co-pyrolysis of cellulose (CL) together with polyethylene (PE) was investigated according to thermogravimetric analysis (TGA). It is found that the involvement of transition metals acting as catalysts could promote the decomposition of individual component (CL and PE) in the mixture. The initial decomposition temperature of CL and PE in the mixture is reduced by 91–136 °C and 8–15 °C, respectively, after the addition of transition metals in comparison with that of the mixture of CL and PE. Meanwhile, transition metals could intensify the synergistic interactions between CL and PE, especially during the pyrolysis stage assigned to CL decomposition. The maximum difference of weight loss in this stage is −9.30% to −14.10% for transition metals treated-mixtures while that of the mixture without transition metal treatment is −2.99%. Kinetic results show that the co-pyrolysis of transition metal-involved CL/PE mixtures can be well described as two consecutive first order reactions. The activation energy (E) of CL and PE in the mixture is reduced by 53.21–80.53 kJ/mol and 8.23–12.36 kJ/mol, respectively, as transition metals were involved. In addition, the content of transition metal makes a large influence on the thermal behavior and kinetics of co-pyrolysis of CL/PE mixture. [ABSTRACT FROM AUTHOR]

Recently, photo switching porous materials have been widely reported for low energy costed CO2 capture and release via simply remoted light controlling method. However, most reported photo responsive CO2 adsorbents relied on metal organic framework (MOFs) functionalisation with photochromic moieties, and MOF adsorbents still suffered from chemically and thermally unstable issues. Thus, further metal free and highly stable organic photoresponsive adsorbents are necessary to be developed. CTFs, because of their high porosity and stability, have attracted great attention for CO2 capture. Considering the high CO2 uptake capacity and structural tunability of CTFs, it suggests high potential to fabricate the photoswitching CTF materials by the same functionalisation method as MOFs. Herein, the first series of photo switching CTFs were developed for low energy CO2 capture and release. Apart from that, the CO2 switching efficiency could be doubled either through the azobenzene numbers adjusting method or through the previously reported structural alleviation strategy. Furthermore, the pore size distribution of azobenzene functionalised PCTFs also could be tuned under UV exposure, which may contribute to the UV light induced decrease of CO2 uptake capacity. These photoswitching CTFs represented a new kind of porous polymers for low energy costed CO2 capture. [ABSTRACT FROM AUTHOR]

Recently, photo switching porous materials have been widely reported for low energy costed CO2 capture and release via simply remoted light controlling method. However, most reported photo responsive CO2 adsorbents relied on metal organic framework (MOFs) functionalisation with photochromic moieties, and MOF adsorbents still suffered from chemically and thermally unstable issues. Thus, further metal free and highly stable organic photoresponsive adsorbents are necessary to be developed. CTFs, because of their high porosity and stability, have attracted great attention for CO2 capture. Considering the high CO2 uptake capacity and structural tunability of CTFs, it suggests high potential to fabricate the photoswitching CTF materials by the same functionalisation method as MOFs. Herein, the first series of photo switching CTFs were developed for low energy CO2 capture and release. Apart from that, the CO2 switching efficiency could be doubled either through the azobenzene numbers adjusting method or through the previously reported structural alleviation strategy. Furthermore, the pore size distribution of azobenzene functionalised PCTFs also could be tuned under UV exposure, which may contribute to the UV light induced decrease of CO2 uptake capacity. These photoswitching CTFs represented a new kind of porous polymers for low energy costed CO2 capture. [ABSTRACT FROM AUTHOR]

[Display omitted] • RWWP-1,2,5,6 achieved a greater pyrolysis performance than RWWP-3,4. • The activation energy for RWWP ranged from 131.04 kJ mol−1 to 171.04 kJ mol−1. • RWWP samples could be identified by Py-TG/MS: PS, PE, PET, PP. • High-value CNTs can be obtained from RWWP-1,2,5,6 by catalytic pyrolysis process. • The carbon yield and CNTs purity top at 32.21 wt% (RWWP-1) and 93.04 % (RWWP-2). The investigation of the pyrolysis behaviour of real-world waste plastics (RWWP) and using them as the feedstock to produce carbon nanotubes (CNTs) could serve as an effective solution to address the global waste plastics catastrophe. This research aimed to characterize the pyrolysis behaviour of RWWP via thermogravimetric analysis (TG) and fast pyrolysis-TG/mass spectrometry (Py-TG/MS) analyses. Activation energies (131.04 kJ mol−1 –171.04 kJ mol−1) for RWWP pyrolysis were calculated by three methods: Flynn-Wall-Ozawa (FWO) method, Kissinger-Akahira-Sunose (KAS) method, and Starink method. Py-TG/MS results indicated that the RWWP could be identified as polystyrene (RWWP-1), polyethylene (RWWP-2), polyethylene terephthalate (RWWP-3, 4), and polypropylene (RWWP-5, 6). In addition, RWWP-1, 2, 5, 6 outperform RWWP-3 and 4 as sources of carbon for producing CNTs. The results showed a high carbon yield of 32.21 wt% and a high degree of CNT purity at 93.04%. [ABSTRACT FROM AUTHOR]

Producing hydrogen from catalytic gasification of biomass represents an interesting process to facilitate the development of hydrogen economy. However, the design of catalyst is a key challenge for this technology. In this work, cost-effective Ca added Ni-based catalysts were developed and studied for producing hydrogen with a fixed-bed reactor. The relationship between Ca addition and the performance of catalyst in terms of the yield of hydrogen and catalyst deactivation (metal sintering and coke formation) was studied. The results showed that hydrogen production was largely enhanced when Ca was added, as the yield of hydrogen was enhanced from 10.4 to 18.2 mmol g −1 sample in the presence of Ca-based catalyst. However, the yield and concentration of hydrogen were kept at similar levels with the increase of Ca. By normalizing the yield of hydrogen in relation to the amount of Ni presented inside the catalyst, the hydrogen yield per mole of nickel was increased from 50 g Ni −1 (0.1Ca catalyst) to 80 g Ni −1 (0.8Ca catalyst) when the Ca addition was increased from 10 mol% to 80 mol%. TPO-FTIR analysis of the experimented catalysts showed that 0.5 Ca catalyst had the highest amount of coke formation, in particular, most of the deposited carbons were amorphous which could deactivate the catalyst seriously. It is therefore concluded that the addition of cost-effective Ca could enhance the yield of hydrogen from biomass gasification. However, the concentration of Ca in the catalyst needs to be controlled to mitigate the generation of coke on the used catalyst. [ABSTRACT FROM AUTHOR]

The conversion of CO2 with CH4 into liquid fuels and chemicals in a single-step catalytic process that bypasses the production of syngas remains a challenge. In this study, liquid fuels and chemicals (e.g., acetic acid, methanol, ethanol, and formaldehyde) were synthesized in a one-step process from CO2 and CH4 at room temperature (30 °C) and atmospheric pressure for the first time by using a novel plasma reactor with a water electrode. The total selectivity to oxygenates was approximately 50-60 %, with acetic acid being the major component at 40.2 % selectivity, the highest value reported for acetic acid thus far. Interestingly, the direct plasma synthesis of acetic acid from CH4 and CO2 is an ideal reaction with 100 % atom economy, but it is almost impossible by thermal catalysis owing to the significant thermodynamic barrier. The combination of plasma and catalyst in this process shows great potential for manipulating the distribution of liquid chemical products in a given process. [ABSTRACT FROM AUTHOR]

The conversion of CO2 with CH4 into liquid fuels and chemicals in a single-step catalytic process that bypasses the production of syngas remains a challenge. In this study, liquid fuels and chemicals (e.g., acetic acid, methanol, ethanol, and formaldehyde) were synthesized in a one-step process from CO2 and CH4 at room temperature (30 °C) and atmospheric pressure for the first time by using a novel plasma reactor with a water electrode. The total selectivity to oxygenates was approximately 50-60 %, with acetic acid being the major component at 40.2 % selectivity, the highest value reported for acetic acid thus far. Interestingly, the direct plasma synthesis of acetic acid from CH4 and CO2 is an ideal reaction with 100 % atom economy, but it is almost impossible by thermal catalysis owing to the significant thermodynamic barrier. The combination of plasma and catalyst in this process shows great potential for manipulating the distribution of liquid chemical products in a given process. [ABSTRACT FROM AUTHOR]

Anaerobic digestion of agricultural waste for producing biogas as a renewable energy source is an established and promising technological option, producing a huge quantity of solid digestate as residue waste. Valorization of solid digestate into high-value products is necessary to make the anaerobic digestion process more cost-effective and enhance environmental benefits. In this study, activated carbon was fabricated from solid digestate with phosphoric acid activation in the fixed bed reactor. The physicochemical properties of the activated carbons have been analyzed by elemental analysis, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and N 2 adsorption and desorption isotherms. The effect of H 3 PO 4 /digestate char impregnation ratio on structural and morphological change of the produced activated carbon was tested, and the function of H 3 PO 4 in the activation procedure was discussed. The results indicated that an appropriate H 3 PO 4 /digestate char ratio was useful for the creation of pore structure. The highest surface area of 201 m2/g was attained at H 3 PO 4 /char ratio of 2 and at 600 °C. The potential for the use of the prepared activated carbon for CO 2 capture was also evaluated thermogravimetrically under dynamic conditions, indicating good cyclic stability. This study provides the feasibility of integrating anaerobic digestion for biogas with subsequent activated carbon production from solid digestate. • H 3 PO 4 /digestate impregnation ratio greatly affected textural and surface property of activated carbons. • The SiO 2 in digestate char could react with P to form silicon diphosphate during H 3 PO 4 activation. • Digestate-derived activated carbon has a good CO 2 capture cyclic stability. [ABSTRACT FROM AUTHOR]

Biomass gasification is a promising technology to produce renewable syngas used for energy and chemical applications. However, biomass gasification has challenges of low process energy efficiency, low syngas production with low H 2 /CO ratio and the sintering of biomass ash which limit the deployment of the technology. This work investigated the influence of in-situ generated heat from CaO–CO 2 on cellulose CO 2 gasification using a fixed bed reactor, thermogravimetric analysis-Fourier transform infrared spectroscopy (TGA-FTIR) and differential scanning calorimetry (DSC). Experimental results indicate an approximate 20 °C temperature difference in the fix-bed reactor between cellulose CO 2 gasification with the energy compensation of CaO carbonation (denoted auto-thermal biomass gasification) and conventional CO 2 gasification of cellulose after the power of external furnaces were turned off. Around 5 times H 2 /CO molar ratio is obtained after switching off the power in the auto-thermal biomass gasification compared with conventional gasification. The gas yield enhances significantly from 0.29 g g−1 cellulose to 0.56 g g−1 cellulose when CaO/cellulose mass ratio increases from 0 to 5. Furthermore, the TGA-FTIR results demonstrate the feasibility of adopting energy compensation of CaO carbonation to reduce the gasification temperature. DSC analysis also proves that the released heat from the CaO–CO 2 reaction reduces the required energy for cellulose degradation. • Autothermal and conventional gasification are compared. • Higher H 2 /CO molar ratio was obtained at 650 °C in the autothermal gasification. • The gas yield increases with the increase of CaO/cellulose mass ratio. • The CaO–CO 2 reaction reduces the required energy for cellulose degradation. [ABSTRACT FROM AUTHOR]

[Display omitted] • The thermal application of carbon nanotube from waste plastic was firstly studied. • The thermal conductivity of phase change composite material increased by 104%. • Latent heat capacity of phase change composite material retains 90.7%. • The produced carbon nanotube shows similar potential as commercial carbon nanotube. • This phase change nanocomposite is promising for battery thermal management. Carbon nanotube (CNT), has been demonstrated as a promising high-value product from thermal chemical conversion of waste plastics and securing new applications is an important prerequisite for large-scale production of CNT from waste-plastic recycling. In this study, CNT, produced from waste plastic through chemical vapor deposition (pCNT), was applied as a nanofiller in phase change material (PCM), affording pCNT-PCM composites. Compared with pure PCM, the addition of 5.0 wt% pCNT rendered the peak melting temperature increase by 1.3 ℃, latent heat retain by 90.7%, and thermal conductivity increase by 104%. The results of morphological analysis and leakage testing confirmed that pCNT has similar PCM encapsulation performance and shape stability to those of commercial CNT. The formation of uniform pCNT cluster networks allowed for a large CNT loading into the PCM on the premise of free phase change, responsible for the high thermal conductivity inside the homogeneous phase. Thus, the resulting capillary forces retained a high latent heat capacity and suitable melting temperature and prohibited PCM leakage from the matrix to the outside during re-melting as the pCNT loading ratio increased. Therefore, the as-prepared pCNT-PCM composite is believed to have similar potential to cCNT and shows prominent performance as a flowable conductive filler for battery thermal management systems. [ABSTRACT FROM AUTHOR]

Engineered biochar derived from wood waste pyrolysis in molten salts were developed for effective CO 2 /N 2 separation. The production conditions were customized to obtain the biochar with high CO 2 capture capacity and CO 2 /N 2 selectivity by tuning the type of molten salts (MgCl 2 -KCl, ZnCl 2 -KCl, ZnCl 2 -NaCl-KCl, and K 2 CO 3 -Na 2 CO 3 -Li 2 CO 3), salt/feedstock ratios (1:1 and 3:1) and pyrolysis temperatures (600 and 800 °C). High temperature (800 °C) and moderate salt loading (salt/feedstock ratio of 1:1) benefited the CO 2 adsorption by providing an increased surface area and highly dispersed metal species as adsorption sites. PSL-3-800 and PSL-3-600 (K 2 CO 3 -Na 2 CO 3 -Li 2 CO 3 biochar) showed the highest CO 2 capacity (4.5 mmol g−1, 0 °C, 100 kPa) and the highest CO 2 /N 2 selectivity (28.5), respectively, among the engineered biochar developed in this study. In addition, ZP-3-600 showed the highest selection parameter (S) in both PSA and VSA processes, indicating the promising CO 2 capture performance under PSA/VSA conditions. A high recovery rate (89%) of molten salts was achieved. These results suggest a new pathway for upcycling biowaste as eco-friendly and effective adsorbents for gas adsorption and separation. [Display omitted] • Molten salt-assisted biochars were prepared for CO 2 capture from N 2. • K 2 CO 3 -Na 2 CO 3 -Li 2 CO 3 engineered biochar showed the highest CO 2 capacity. • A high pyrolysis temperature (800 °C) facilitated the formation of large surface area. • Separation potential was evaluated under pressure/vacuum swing adsorption conditions. • Recovery rate of soluble molten salt in the biochar was up to 89%. [ABSTRACT FROM AUTHOR]

• Calcium looping and chemical looping are isothermally integrated for CO 2 capture and CO generation. • Ni promoted Fe-CaO achieves effective and stable cyclic calcium chemical dual looping. • Ni promoted Ca 2 Fe 2 O 5 plays as the oxygen carrier to achieve the in-situ chemical looping. • Ca 2 Fe 2 O 5 improves the calcium looping stability by acting as a thermally stable physical barrier. • Steam or air purge after hydrogenation is effective to avoid CO generation in carbonation. Reverse water–gas shift reaction using renewable H 2 is a promising route for CO 2 upgrade, however, it is restricted by the equilibrium. The chemical looping reverse water–gas shift reaction using oxygen carriers (i.e. Fe) has proven a more effective CO 2 utilization process to produce CO. However, CO 2 with high purity is needed to obtain concentrated CO. Herein, we propose a calcium chemical dual looping using one-pot sol–gel synthesized Ca-Fe dual functional materials (DFMs). The CO 2 in the exhaust gas (∼10% CO 2) can be captured and transformed into carbonates and then in-situ converted into CO through continuous chemical looping in H 2 atmosphere. This process avoids CO 2 enrichment, storage and transportation and simultaneously realizes efficient CO 2 conversion. The Ca-Fe DFMs possessed significantly improved catalytic efficiency (enhanced real-time CO generation rate) compared to CaO. It is found that Ni 1 Fe 9 -CaO could optimally achieve 11.3 mmol g DFM −1 CO yield, 82.5% CO 2 conversion and 99.9% CO selectivity at 650 °C. Notably, Ni 1 Fe 9 -CaO displayed high CO 2 conversion (>80%) and CO selectivity (>99.9%) during the cycle tests and possessed enhanced stability in relation to CO yield after 10 cycles (20.9% and 35.5% decrease for Ni 1 Fe 9 -CaO and CaO, respectively). Herein, Ca 2 Fe 2 O 5 plays two roles: acting as an oxygen carrier for in-situ chemical looping to produce CO and a thermally stable physical barrier to retard the sintering of CaO. It is noted that Fe-related species could be reduced into the metallic state at the end of hydrogenation, resulting in CO formation in the following CO 2 capture process. [ABSTRACT FROM AUTHOR]