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The global emission of CO 2 through fossil fuel combustion is still increasing, which is a major challenge for the international community. An integrated carbon capture and utilisation (ICCU) process with a CaO-based sorbent is a promising alternative to effectively reduce emissions. In this work, a comparative thermodynamic analysis of two CaO-based sorbents (commercial and sol-gel CaO) was performed for one cycle of ICCU. In addition, the influence of temperature was investigated from 600 to 750 °C in terms of the degree of CO 2 conversion. Thermodynamic calculations were based on the actual gas composition and developed model, where heat consumption and entropy generation were calculated. The results indicate that the degree of CO 2 conversion decreased from 84.6 to 41.2% and from 84.1 to 62.4% for the sol-gel and commercial material, respectively, as the temperatures increased. Furthermore, the total heat consumption during one cycle decreased with higher temperatures. The total amount of consumed heat decreased from 19.1 to 5.9 kJ/g and from 24.7 to 5.4 kJ/g for sol-gel and commercial CaO, respectively. Although commercial CaO always requires more heat during one cycle. Moreover, for both materials, the lowest generation of entropy was calculated at 650 °C with values of 9.5 and 10.1 J/g·K for the sol-gel and the commercial CaO, respectively. At all temperatures, the commercial CaO generated a greater entropy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In order to cope with the global energy crisis and environmental pollution problems, there are urgent needs for clean energy such as biomass-derived hydrogen. CaO is effective to promote hydrogen production from biomass gasification due to its high capacity of in-situ CO 2 capture. In this work, a two-stage fixed bed reactor was used to produce hydrogen by catalytic conversion of biomass with and without in-situ CO 2 capture. In addition, three Ni loadings (5 wt%, 10 wt%, and 20 wt%) supported by Al 2 O 3 and sol-gel CaO have been prepared and tested. The BET analysis shows the surface area of the catalysts increases first and then decreases with the increase of Ni loading. Results from high-resolution transmission electron microscopy (HRTEM) images reveals that NiO particles are well distributed over the porous CaO. The X-ray diffraction (XRD) analysis indicates the NiO nanocrystalline size is increased with increasing Ni loading on Ni/Al 2 O 3 , and the most homogeneous dispersion was shown by 10 wt% Ni/CaO. Around 666 mgCO 2 /gCaO of CO 2 adsorption capacity and 850 min stability were obtained using the sol-gel CaO sorbent. Compared to the reference Ni/Al 2 O 3 catalysts, the resistance of carbon deposition on the Ni/CaO results in a lower coke deposition, which is attributed to the basicity of the catalysts. In addition, the increase of loading promotes the decomposition of biomass-derived oxygenated compounds. Much more hydrogen is obtained using the Ni/CaO catalysts compared with Ni/Al 2 O 3 due to in-situ CO 2 capture. However, the sintering and particle agglomeration using the 20 wt% Ni-catalyst might be responsible for the reduction of hydrogen production. The highest H 2 concentration of 19.32 vol% at 424 °C was obtained when the 10 wt% Ni/CaO catalyst was used., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Direct air capture (DAC) of CO 2 is considered one of the most promising carbon capture methods to reduce ambient CO 2 concentration for climate change mitigation. Biochar represents an attractive adsorbent for DAC because it is environmentally friendly and cost-effective. In this work, KOH-activated bamboo biochar shows the CO 2 capture capacity of 3.49 mmol g−1 (25 °C, 1 bar), and it is used as an adsorbent to perform direct air capture using a fixed-bed reactor with an ambient CO 2 capture capacity of up to 51.74 μmol g−1. Furthermore, the effect of relative humidity on CO 2 adsorption by biochar was investigated and exhibited promising stability under 2.7% relative humidity. However, the biochar activity for CO 2 capture is reduced to 63.88% under 67.1% humidity after 50 cycles. [Display omitted] • KOH was used to activate bamboo-derived biochar. • Bamboo biochar was investigated in direct air capture of CO 2. • Gas selectivity of biochar during direct air capture. • Effect of relative humidity on direct air capture efficiency. [ABSTRACT FROM AUTHOR]

This study assesses the potential of the eggshells as a promising and alternative CO 2 adsorbent. With the aim of enhancing the CO 2 capture performance of raw eggshell, it was modified by sol-gel citric acid treatment. Both adsorbents were characterized by N 2 adsorption-desorption, XRF, XRD and SEM techniques. Preliminary adsorption tests in TGA revealed that the acid-modified eggshell achieved significantly higher carbonation conversion than the raw eggshell adsorbent in the 650–750 ºC adsorption temperature range, reaching a carbonation conversion of 69% at 700 ºC. The cyclic performance of the modified eggshell, tested in TGA at 700 ºC under 15 vol% CO 2 , confirmed that sol-gel acid treatment led to a very stable adsorbent, with a slight improvement in CO 2 adsorption capacity during the first four cycles (from 0.54 to 0.58 g CO2 g ads −1), followed by stable performance due to self-reactivation phenomena. Moreover, additional experiments were carried out in a fixed bed reactor under more realistic conditions to study the influence of temperature (600–750 ºC) and CO 2 flow rate (50–125 mL min−1) using the modified eggshell. An increase in temperature under 15 vol% CO 2 stream led to a decrease in the carbonation conversion of the adsorbent, with the maximum CO 2 uptake at 600 ºC (0.64 g CO2 g ads −1). Regarding the role of the CO 2 flow rate at 700 ºC, increasing from 75 to 125 mL min−1 CO 2 had minimal effect, maintaining a capture amount of approximately 0.49 g CO2 g ads −1. These results confirmed the potential of the acid-modified eggshell as a low-cost and environmental friendly adsorbent for CO 2 capture, which indeed may significantly improve the economic feasibility of the CCUS processes. • Sol-gel citric acid treatment was performed to eggshells to enhance its CO 2 uptake. • The morphology of the raw eggshell adsorbent was modified after acidified sol-gel. • Self-reactivation phenomena was observed for modified eggshell after few cycles. • CO 2 capture capacity of 0.64 g CO2 g ads −1 was attained under optimum conditions. [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]

Carbon capture and sequestration technologies are essential to reduce CO 2 emissions which are responsible for global warming. Carbon-based materials can play an important role in the reduction of CO 2 emissions. These materials are normally produced from biomass through technologies such as pyrolysis and hydrothermal carbonization. The type of biomass feedstock and biomass conversion conditions can significantly affect the textual properties and surface chemistry of the carbon materials. Various modification methods such as material activation or N-doping can improve the properties of carbon materials to obtain better CO 2 capture effects. This review summarizes recently reported research in the areas of using biomass-based materials for CO 2 capture. The technologies of biomass conversion to carbon materials and modification of the carbon materials are critically analyzed. Meanwhile, the mechanisms of the CO 2 capture process and research of different modification carbon materials for CO 2 capture are also discussed. Finally, potential future research directions are suggested to promote carbon capture using biomass-based materials. • The preparation technologies of carbon materials and influencing factors are discussed. • Traditional and emerging carbon material modification methods are summarized. • Recent researches of carbon materials for CO 2 capture and its capture mechanisms are discussed. • Future research directions and challenges in carbon materials for CO 2 capture are discussed. [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]

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]

The activity and stability of a 10 wt%NiO/CaO catalyst were tested in the sorption enhanced ethanol steam reforming (SEESR) in a fluidized bed reactor. The effect of temperature in the 600–750 °C range was analyzed and the performance of the catalyst at 700 °C was assessed by conducting cycles of SEESR reaction and CO 2 desorption. At zero time on stream, an increase in temperature enhanced ethanol steam reforming reactions, and therefore H 2 production increased from a yield of 20.3 wt% at 600 °C to 22 wt% at 750 °C. However, high temperatures hindered the catalyst sorption performance, i.e., CO 2 capture declined from 7.9 to 2.1 mmol CO2 g cat −1. In order to evaluate the catalyst performance throughout the cycles and relate it with its features, both fresh and deactivated catalysts were characterized in detail by N 2 adsorption-desorption, X-ray fluorescence (XRF), X-ray diffraction (XRD), temperature programmed reduction (TPR) and oxidation (TPO) and transmission electron microscopy (TEM). Subsequent to 12 cycles, the catalyst CO 2 capture performance was slightly lower than that of the fresh one (approximately 7%) and hardly changed in the next cycles. Furthermore, the use of the same temperature for SEESR reaction and CO 2 desorption led to the highest adsorption capacity of the catalyst over multiple cycles. [Display omitted] ● Ni/CaO catalyst efficiently promotes hydrogen production by in-situ CO 2 capturing. ● The maximum CO 2 capture capacity is attained at 600ºC. ● CO 2 capture capacity decreases around 7% subsequent to 22 cycles. ● Isothermal catalyst regeneration maximizes catalyst stability over multiple cycles. [ABSTRACT FROM AUTHOR]

In order to cope with the global energy crisis and environmental pollution problems, there are urgent needs for clean energy such as biomass-derived hydrogen. CaO is effective to promote hydrogen production from biomass gasification due to its high capacity of in-situ CO 2 capture. In this work, a two-stage fixed bed reactor was used to produce hydrogen by catalytic conversion of biomass with and without in-situ CO 2 capture. In addition, three Ni loadings (5 wt%, 10 wt%, and 20 wt%) supported by Al 2 O 3 and sol-gel CaO have been prepared and tested. The BET analysis shows the surface area of the catalysts increases first and then decreases with the increase of Ni loading. Results from high-resolution transmission electron microscopy (HRTEM) images reveals that NiO particles are well distributed over the porous CaO. The X-ray diffraction (XRD) analysis indicates the NiO nanocrystalline size is increased with increasing Ni loading on Ni/Al 2 O 3 , and the most homogeneous dispersion was shown by 10 wt% Ni/CaO. Around 666 mgCO 2 /gCaO of CO 2 adsorption capacity and 850 min stability were obtained using the sol-gel CaO sorbent. Compared to the reference Ni/Al 2 O 3 catalysts, the resistance of carbon deposition on the Ni/CaO results in a lower coke deposition, which is attributed to the basicity of the catalysts. In addition, the increase of loading promotes the decomposition of biomass-derived oxygenated compounds. Much more hydrogen is obtained using the Ni/CaO catalysts compared with Ni/Al 2 O 3 due to in-situ CO 2 capture. However, the sintering and particle agglomeration using the 20 wt% Ni-catalyst might be responsible for the reduction of hydrogen production. The highest H 2 concentration of 19.32 vol% at 424 °C was obtained when the 10 wt% Ni/CaO catalyst was used. Image 1 • Bifunctional Ni/CaO and Ni/Al 2 O 3 catalysts were studied for biomass gasification. • CNTs are main carbons on the surface of the used Ni/CaO catalyst. • Amorphous carbons are largely found on the used Ni/Al 2 O 3. • 10 wt% Ni/CaO produced the highest hydrogen yield. [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]

A coaxial dielectric barrier discharge (DBD) reactor has been developed for plasma-catalytic conversion of pure CO 2 into CO and O 2 at low temperatures (<150 °C) and atmospheric pressure. The effect of specific energy density (SED) on the performance of the plasma process has been investigated. In the absence of a catalyst in the plasma, the maximum conversion of CO 2 reaches 21.7% at a SED of 80 kJ/L. The combination of plasma with BaTiO 3 and TiO 2 photocatalysts in the CO 2 DBD slightly increases the gas temperature of the plasma by 6–11 °C compared to the CO 2 discharge in the absence of a catalyst at a SED of 28 kJ/L. The synergistic effect from the combination of plasma with photocatalysts (BaTiO 3 and TiO 2 ) at low temperatures contributes to a significant enhancement of both CO 2 conversion and energy efficiency by up to 250%. The UV intensity generated by the CO 2 discharge is significantly lower than that emitted from UV lamps that are used to activate photocatalysts in conventional photocatalytic reactions, which suggests that the UV emissions generated by the CO 2 DBD only play a very minor role in the activation of the BaTiO 3 and TiO 2 catalysts in the plasma-photocatalytic conversion of CO 2 . The synergy of plasma-catalysis for CO 2 conversion can be mainly attributed to the physical effect induced by the presence of catalyst pellets in the discharge and the dominant photocatalytic surface reaction driven by the plasma. [ABSTRACT FROM AUTHOR]

Syngas production (H 2 and CO) from carbon dioxide reforming of high density polyethylene (HDPE) over Ni–Al catalyst was evaluated in a two-stage fixed bed reactor. Syngas production was favoured by CO 2 addition, with the highest production of 138.81 mmol syngas g − 1 HDPE , which was about six times higher than non-catalytic, non-CO 2 addition. The catalytic performances of nickel-based catalysts with different promoter metals (Cu, Mg and Co) in the CO 2 reforming of HDPE were also studied. It was found that Ni–Co–Al had an excellent anti-coking performance, with no detectable formation of coke on the catalyst surface. Moreover, the syngas production was significantly improved by the addition of Co compared to the Cu and Mg metal promoters. The CO 2 conversion for Ni–Co–Al catalyst was also the highest at 57.62%. Further investigation of the effect of Co concentration on CO 2 reforming of HDPE showed that the higher Co content, the higher the syngas production and CO 2 conversion. [ABSTRACT FROM AUTHOR]

The emerging integrated CO 2 capture and utilization (ICCU) potentially contributes to net zero emissions with low cost and high efficiency. The catalytic performance in ICCU process is highly restricted by the equilibriums of carbonate decomposition and dry reforming of methane (DRM). Here, we engineer a unique yolk-shell dual functional nanoreactor construction to improve the catalytic performance via confined catalysis. By tailoring the carbonates decomposition kinetics and confining the CO 2 diffusion path, ∼92% CO 2 conversion is achieved over (Ni/Ca)@Si and shows no distinct activity loss in 10 cycles at 650 °C. The formed Ca 2 SiO 4 shells restrain the sintering of CaO yolks by acting as physical barriers, and stabilize the Ni particle size. It is also confirmed on in situ DRIFTS that the integrated DRM might occur via carbonyls, formates and CHO intermediates, in which formates species are highly dependent on Ni-carbonates interfaces. [Display omitted] • Ni-functionalized Ca@Si yolk-shell nanoreactors achieves effective CO 2 capture and in situ methane dry reforming. • Yolk-shell structure promote the catalytic performance by confined catalysis. • Ca 2 SiO 4 shell stabilizes both the CaO yolk and catalytic sites. • Formates are dependent on Ni-carbonates interfaces. [ABSTRACT FROM AUTHOR]

• Ni/SiO 2 activation and CO 2 supply are pivotal for ICCU-DRM. • Reverse Boudouard reaction plays an essential role in CO 2 conversion. • Ni/SiO 2 -CaO interaction needs to be optimised to enhance ICCU-DRM efficiency. • Synergies exist between Ni/SiO 2 catalyst and CaO sorbent in CO 2 conversion. Integrated carbon capture and utilisation (ICCU) is an emerging technology for simultaneous CO 2 adsorption and conversion into value-added products. This provides a more sustainable approach compared to carbon capture and storage. Dual-functional materials (DFMs) that couple CO 2 sorbents (e.g. CaO) and catalysts (e.g. Ni) enable direct utilisation of sorbed CO 2 for reactions like dry reforming of methane (DRM). However, the potential interactions between sorbent and catalyst components within DFMs may induce distinct mechanisms compared to individual materials. Elucidating these synergies and interfacial phenomena is vital for guiding the rational design of DFMs. This article investigates the respective roles of Ni/SiO 2 catalyst and sol–gel synthesised CaO sorbent in integrated CO 2 capture and utilisation via dry reforming of methane (ICCU-DRM) using a decoupling approach. Through decoupled reactor experiments, it is found that Ni/SiO 2 activates CO 2 to react with carbon deposits from CH 4 decomposition, achieving maximal CO and H 2 yields of 43.41 mmol g−1 and 46.78 mmol g−1 as well as 87.2 % CO 2 conversion at 650 °C. Characterisation shows that coke would encapsulate Ni nanoparticles and be active for CO 2 conversion via Boudouard reaction, indicating sufficient catalyst-sorbent contact is necessary for CO 2 spillover. In-situ DRIFTS reveals that no obvious CH 4 -CaCO 3 reaction occurs, CO 2 chemisorption on Ni/SiO 2 enables the reverse Boudouard reaction, which is further verified by DFT calculations. The findings elucidate the dependent and synergistic roles of Ni/SiO 2 and CaO/CaCO 3 in ICCU-DRM, and highlight the importance of catalyst-adsorbent interactions in optimising dual-functional materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The presence of acidic sites can accelerate the hydrogenation of carbonate. • ZrO 2 reduce the formation barrier of intermediates in carbonate hydrogenations. • ZrO 2 doped Ni/CaO can quickly complete hydro-methanation of carbonate in ICCU. • Steam reduces the hydrogenation rate of carbonate and improve CO 2 capture capacity. Carbonate hydrogenation is a new path for the conversion of metal carbonate with potentially lower energy consumption and CO 2 emissions comparing to the traditional thermal decomposition, and the integrated CO 2 capture and utilization (ICCU) represents its latest development. However, the slow hydrogenation rate of carbonate at low temperatures is one key scientific challenge for applications. Herein, we report an acidity regulation approach to prepare ZrO 2 -doped Ni/CaO dual-function material with good CO 2 capacity, fast and highly selective conversion below 600 °C for integrated CO 2 capture and utilization by methanation (ICCU-methanation). Experiments and DFT calculations show that the introduction of ZrO 2 as acid sites effectively strengthens *H adsorption and reduces the formation barrier of intermediate *COOH during carbonate hydrogenation. Thus, Ni 10 (ZrO 2) 10 CaO 80 exhibits a CH 4 STY of 14.1 mmol∙min−1∙g Ni −1 at 550 °C, 6 times higher than the reference DFM. Furthermore, the presence of O 2 in flue gas is observed to have no effect on ICCU-methanation, but steam could delay the in-situ methanation. Long-term cyclic test shows that the optimal Ni 10 (ZrO 2) 5 CaO 85 has a stable CO 2 capacity of 7.5 mmol ∙g DFM −1, 98 % CO 2 conversion and 95.5 % CH 4 selectivity under flue gas containing both steam and O 2 at 600 °C, suggesting a good potential to be applied in ICCU-methanation. [ABSTRACT FROM AUTHOR]

Synopsis: Under natural abundant light irradiation and using Azo-CTP as photocatalysts, CO 2 can be converted to fuel in an environmentally friendly water system. [Display omitted] • A series of azobenzene functionalized Azo-CTFs were successfully fabricated. • Through incorporating different amounts and sites of azobenzene pendants, the chemical and optical properties of Azo-CTFs were successfully tuned. • The CO 2 uptake capacity of Azo-mCTF 1 enhanced by 53 % through azobenzene functionalization, up to 48.2 cm3 g−1. After being loaded with palladium, the CO 2 uptake performance was still around 6 times higher than the reported Pt-SA/CTF-1. • Azo-mCTF 1 also suggested a 4 times higher CH 4 evolution rate than Azo-CTF 0 with high selectivity up to 97%. Compared to the reported Pt-SA/CTF-1, both the CH 4 evolution rate and selectivity was dramatically improved. • The optical properties and band gap structure results also support the highest CH 4 evolution rate of Azo-mCTF 1. Covalent triazine polymers, as large π conjugated, highly porous, nitrogen riched organic semiconductors, can play a key role in tackling the fuel energy crisis and global warming issues. However, their development in photocatalytic CO 2 reduction is still rare. More effective strategies to enhance CO 2 reduction activity need to be explored. Herein, different amounts of azobenzene pendants functionalized CTPs: Azo-CTP 0 , Azo-CTP 1 , Azo-mCTP 1 and Azo-CTP 2 , were fabricated for photocatalytic CO 2 reduction with Pd loaded. Among them, Azo-mCTP 1 displayed the highest CO 2 uptake capacity up to 48.2 cm3 g−1 (2.15 mmol g−1) at 273 K, and the highest CH 4 evolution rate in the water system, with selectivity highly up to 97 %. Apart from that, the azobenzene functionalization of Azo-CTP 0 could significantly boost the CO 2 reduction efficiency by 4 times. Therefore, this study provides a potentially general approach for accurately modifying organic semiconductors to enhance photocatalytic performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultra-low CO 2 emissions were achieved in biomass gasification using air. • Cost-effective waste marble powder and gasification agent (air) were employed. • Marble shows superior performance in resisting carbon deposition, only 7.45 wt%. Addressing the high CO 2 emissions from biomass gasification is crucial for enhancing the sustainability and environmental profile of this technology. This work proposes a novel approach by integrating the biomass gasification process with carbon capture and utilisation (IGCCU), to tackle the substantial challenge of traditional biomass gasification, which leads to high CO 2 emissions. Specifically, during the biomass gasification stage, this novel approach successfully captured 14.39 mmol g−1 lignin of CO 2 , based on benchmark conditions. The captured CO 2 is subsequently converted into CO during the hydrogenation stage, achieving a peak CO concentration of 1.58 %. The results reveal that maintaining a marble feeding mass of 6 g and setting the reaction temperatures for gasification, carbon capture, and hydrogenation at 500 °C, 400 °C, and 550 °C, respectively, consistently ensures ultra-low CO 2 emissions throughout the entire process. "Ultra-low CO 2 emissions" specifically refers to the absence of CO 2 signals throughout the entirety of the IGCCU process, encompassing stages such as biomass gasification, CO 2 capture, and CO 2 conversion. Notably, CO 2 conversion and CO selectivity remain at a stable 100 % level over 8 cycles as only CO was generated during the hydrogenation stage, underscoring the excellent stability of this novel technology. Furthermore, the utilisation of low-cost sorbent material (waste marble powder) and the readily available biomass gasification agent (air) enhance the economic feasibility of this new technology while demonstrating robust resistance to carbon deposition. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni 0.05 /CaO 0.95 were evaluated for integrated CO 2 capture and utilization. • NiO needs to be reduced by CH 4 after the CO 2 capture stage to initiate the DRM reaction. • O 2 and moisture triggered Ni and CaO expansion inhibiting NiO reduction and decreasing DFM performance. Global warming and climate change require urgent reduction of CO 2 emissions. Integrated carbon capture and utilisation combined with dry reforming of methane (ICCU-DRM) has the potential to mitigate greenhouse gas emissions by capturing and converting CO 2 and CH 4 into valuable syngas. However, the performance and stability of dual-functional materials (DFMs) are unclear under real-world flue gas conditions, particularly in the presence of steam and O 2. In this study, we elucidated the mechanisms of the performance of a Ni 0.05 /CaO 0.95 DFM under various flue gas conditions and investigated the combined effects of steam and O 2 on CO 2 uptake, CO and H 2 yields and cyclic stability. Our approach includes the synthesis and evaluation of the DFM using advanced characterisation techniques, such as XRD, in-situ infrared spectroscopy, CH 4 -TPR, SEM, EXD, FIB-SEM, BET, and XPS, to gain insights into the properties and behaviour of the DFM under different flue gas conditions. The findings show that under the simulated flue gas condition (10.0 % CO 2 + 6.0 % H 2 O + 6.7 % O 2 /N 2), there was a significant deterioration in performance, with CO 2 uptake of only 5.7 mmol.g-1, average H 2 yield of 11 mmol.g−1 and average CO yield of 6.2 mmol.g−1. While under the ideal condition (10.0 % CO 2 /N 2), the CO 2 uptake, average H 2 yield and average CO yield were 10.7 mmol.g−1, 16.9 mmol.g−1 and 23.1 mmol.g−1, respectively. FIB-SEM and XPS analysis highlighted the combined effect of steam and O 2 on the performance of Ni 0.05 /CaO 0.95 DFM during ICCU-DRM. Notably, the presence of O 2 promoted the oxidation of Ni, resulting in decreased catalytic activity and volumetric expansion of Ni particles. Furthermore, the presence of steam promoted CO 2 adsorption, inducing additional volumetric expansion of the CaO component of DFM. These synergistic expansions form a dense shell on the surface, hindering the reduction of internal NiO, thereby diminishing DFM performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biomass gasification was integrated with CO 2 capture and utilization technology. • 100% CO 2 capture and 100% CO 2 conversion were achieved through IGCCU technology. • High-value syngas (CO and H 2) was produced while achieving a CO 2 net zero process. • 0.95 mmol g−1 CaO g−1 lignin of CO was generated during the CO 2 conversion process. Biomass energy plays a crucial role in mitigating carbon emissions. However, the existing gasification technology faces challenges such as releasing undesirable CO 2 in the produced syngas. Here we propose a new concept for achieving zero CO 2 emissions by integrating gasification with CO 2 capture and utilization (IGCCU) for the first time. During lignin gasification, valuable syngas (H 2 /CO) can be produced, and CO 2 in the gaseous products can be simultaneously captured by CaO. After completing the lignin gasification process, the captured CO 2 can be effectively converted to CO by switching the carrier gas from N 2 to H 2. The results show that the entire process achieves zero CO 2 emissions with carbonation and hydrogenation process at 400 °C and 550 °C, respectively. This approach allows a significant reduction in CO 2 yield from 0.95 mmol g−1 CaO g−1 lignin (benchmark experiment) to nearly 0, using CaO as an adsorbent and catalyst. The disappeared CO 2 was converted into 0.95 mmol g−1 CaO g−1 lignin of CO, by introducing H 2 to the sorbent regeneration stage. Furthermore, excellent cyclic stability has been achieved with zero CO 2 emissions after five cycles and consistent 100% CO 2 conversion during the CO 2 utilization stage. [ABSTRACT FROM AUTHOR]

CCUS technology is an important means to achieve carbon neutralization of energy utilization, in which the ammonia CO 2 -capture method is a relatively mature technology, with some problems (such as low CO 2 absorption efficiency and serious ammonia escape). An ethanol/biochar synergistic ammonia carbon capture technology is proposed, and the mass transfer coefficient is studied by wetted-wall column, so as to assist in proving that biochar and ethanol have synergistic effect on the absorption of CO 2 by ammonia. The simulation shows that the micropores in biochar adsorb and enrich CO 2 , the mesopores and macropores diffuse and transport CO 2 , and dynamically retain free NH 3 , thereby enhancing the mass transfer capacity of CO 2 in the carbon capture system. And the experiment shows that the mass transfer efficiency of biochar-ethanol to the reaction solution is increased by 15.4%, which is higher than that of ethanol (7.1%),but biochar can make ammonia escape seriously. If the ammonia concentration can be maintained constant, the enhancement effect of the pore structure of biochar on the diffusion of CO 2 into ammonia will provide a new direction for the improvement of CO 2 capture by ammonia method. [Display omitted] • Solid-liquid two-phase functional crosslinking enhanced ammonia CO 2 capture. • Biochar promotes the ammonia absorption of CO 2 in the early stage. • As the reaction progresses, biochar inhibits the ammonia absorption of CO 2. [ABSTRACT FROM AUTHOR]

• CO 2 in flue gas could be captured and utilised via integrated DRM. • Ni-Ca interactions limitedly contribute due to poor reducibility and accessibility. • Ni 10 -CaO exhibits optimal CO 2 capture and DRM performance. • Optimal Ni loading provides sufficient surface Ni and limited sintering. • Ni particle size does not affect the ICCU performance. Reducing carbon emissions remains a formidable challenge under present energy demands and structures. Integrated CO 2 capture and utilisation (ICCU) provides a promising pathway for directly capturing and simultaneously utilising CO 2 from the diluted exhaust gas. Dry reforming of methane (DRM) can be integrated into the step of catalytic conversion of the captured CO 2 with the advantages of utilising two greenhouse gases to yield valuable syngas (CO + H 2). The process has great challenges of materials development for efficient performance, in particular under realistic conditions such as the presence of O 2 and H 2 O in the flue gas. This work investigated the ICCU-DRM using simulated flue gases (10 % CO 2 + 6.7 % O 2 + 6.0 % H 2 O) in the presence of Ni-CaO dual functional materials, aiming to optimise Ni loading and metal support interaction. It is found that Ni would significantly sinter and further affect the morphologies of CaO adsorbents, resulting in poorer CO 2 capture performances. More notably, the Ni was firstly oxidised during CO 2 capture and subsequently went through a pre-reduction period in the DRM step. Increased Ni loading decreased the difficulty of activation; however, it derived in more severe carbon deposition. To avert the direct contact of carbon deposition and flue gas, extra carbon steam gasification was introduced, and higher Ni loading contributed to selectively yielding syngas as a by-product. The Ni 10 -CaO DFM optimally performed <150 s pre-reduction delay, ∼85 % CO 2 conversion and ∼2 H 2 :CO ratio in the DRM step and ∼75 % CO selectivity in the CSG step at 650 °C. The interaction between Ni and CaO poorly contributes to the performance due to the poor reducibility and accessibility, and the Ni particle size effects only play as spectators in this integrated process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three Ca-MOFs with specific structures were employed as precursors to obtain nano CaO through a two-step thermal transition process. • LAC MOF-derived CaO spheres with an average size of 100 nm achieved a fast adsorption capacity of 11.8 mmol g−1 after 4 cycles. • The structure transition from LAC MOF to CaO spheres was deeply investigated. Calcium looping is considered to be one of the best approaches for industrial CO 2 high-temperature capture, whereas current CaO-based sorbent suffers poor cyclic performance, especially the relations between precursor structure and CO 2 fast adsorption capacity still need to be further revealed. In this work, three calcium-based metal frameworks (Ca-MOFs) with specific structures were employed as precursors to obtain nano CaO through a two-step thermal transition process. It was found that LAC MOF-derived CaO achieved a fast adsorption capacity of 11.8 mmol g−1 (78 % of total adsorption) after 4 cycles. This was because the fiber bundle-like original LAC MOF structure changed gradually to nanosheets after 600 °C pyrolysis and finally formed regular CaO spheres with an average size of 100 nm after an 800 °C -calcination, thereby preventing further aggregation of CaO particles during the thermal transition process. In addition, the adsorption performance did not rely on pore structure, and thus pore-blocking showed little influence on the performance of CO 2 capture. Hence, high stability can be achieved simply by avoiding particle sintering. The systematic study marks the significance of precise tailoring of nano-CaO for achieving the desired performance of CO 2 fast adsorption. [ABSTRACT FROM AUTHOR]

• CO 2 from flue gas could be directly utilised via ICCU-DRM process. • The H 2 O promotes CO 2 capture kinetics, the O 2 throughly oxidises Ni into NiO. • The NiO reduction is not instant and further deteriorated by CaCO 3 coverage. • Carbon deposition contributes to CO, CH 4 and H 2 generation during CO 2 capture. • Introducing steam to consume carbon maintains the harmless CO 2 capture. Integrated CO 2 capture and utilisation via dry reforming of methane (ICCU-DRM) represents a promising and profitable route for directly capturing and converting CO 2 from various CO 2 sources. However, the influence of realistic flue gas conditions on ICCU-DRM remains unknown and challenging. Herein, we investigated the influence of the presence of H 2 O and O 2 in power plant flue gas on integrated CO 2 capture and DRM using Ni 10 -CaO dual functional material (DFM). It is found that H 2 O promoted the kinetics of CO 2 capture, while the O 2 oxidised Ni into NiO and prohibited the performance of utilisation of the captured CO 2 during DRM. Specifically, the delay of pre-reduction of NiO and the coverage of catalytic sites by the formed CaCO 3 decreased the process performance and efficiency. The reduction of NiO would instantly generate CO 2 and hinder the contact between CH 4 and Ni, resulting in a lower initial catalytic performance during the CO 2 utilisation (DRM) of ICCU. Due to the occurrence of CH 4 decomposition in DRM, the following CO 2 capture step would produce CO in the flue gas, which could be problematic, owing to the carbon gasification reactions. An extra step of carbon steam gasification (CSG) after DRM could effectively remove most of the deposited carbon and by-produce syngas. Subsequently, the small amount of carbon residue after the CSG step could be preferentially combusted by O 2 into CO 2 in flue gas, and then be captured by CaO instead of generating CO. This study demonstrates the feasibility and challenges of ICCU-DRM under simulated power plant flue gas conditions and provides potential insights for future investigation and deployment of this integrated process. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) capture is critical for emission reduction. Biochar is a promising adsorbent for CO 2 capture. In this work, the effect of relative humidity and biochar activation with steam or KOH treatment on CO 2 capture was investigated. The results demonstrate that the biochar sample activated by KOH has a high CO 2 capture capacity (50.73 mg g−1). In addition, the biochar after 1.0 h of steam treatment showed a carbon capture capacity of 38.84 mg g−1. The results also show that the capture ability of biochar decreased as CO 2 concentration decreased from 100% to 15%. The relative humidity had a negative impact on CO 2 capture over biochar. The CO 2 capture capability of biochar materials treated by steam decreased by a range of 31.38%–62.89% as the relative humidity rose from 8.8% to 87.9%. Furthermore, the lifetime of biochar samples at various relative humidity shows that increased relative humidity had a negative impact on CO 2 adsorption due to water molecules occupying active sites. • KOH activated wood pellet biochar has a CO 2 capture capacity of 50.73 mg g−1. • CO 2 capture performance of Chemical activated biochar outperforms physically activated biochar. • High relative humidity has a negative effect on CO 2 adsorption of biochar. • Biochar shows higher stability under dry conditions than moisture conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mechanism of integrated carbon capture and utilization (ICCU) over 10 %NiCaO was investigated by the time-resolved operando XAS/DRIFTS/MS. • The influence of a reduction pretreatment on the process and the products formed was deeply investigated. • The Ni active species are oxidized by CO 2 in the 1st stage of ICCU (carbon capture) , leading to the formation of NiO and CO. • Heating 10% NiCaO to the operating temperature under hydrogen resulted in a switch of predominant product from CO to CH 4. An integrated carbon capture and utilization (ICCU) process present an ideal solution to address anthropogenic carbon dioxide (CO 2) emissions from fossil fuel-driven electricity production, allowing for capturing and subsequent utilization of CO 2 instead of current release into the atmosphere. Effective dual-functional materials (DFMs), through the combination of CO 2 sorbents and catalysts, can not only capture CO 2 but also convert it into higher-value chemicals, such as CH 4 or CO, under isothermal conditions within a single reactor are highly desirable for ICCU processes. In this study, we investigate the mechanism of ICCU over 10 %NiCaO by the time-resolved operando XAS/DRIFTS/MS and the influence of a reduction pretreatment on the process and the products formed. During the 1st stage of the ICCU process (carbon capture), CaO adsorbs CO 2 resulting in bicarbonate, carbonate, and formate species formation. At the same time, the Ni catalytic active species are oxidized by CO 2 , leading to the formation of NiO and CO. However, pre-treating the same DFM under hydrogen, during heating to operating temperature, resulted in a switch to CH 4 production, suggesting the presence of high levels of surface adsorbed H 2. During the 2nd stage of ICCU (CO 2 conversion), the NiO generated during capture is reduced by H 2 to metallic Ni, which facilitates the reduction of bicarbonates, carbonates, and formats, via H 2 dissociation, to produce and liberate gaseous CO. Thus, both adsorption and catalytic sites are regenerated for the subsequent ICCU cycle. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni/supports-CaO are active in integrated CO 2 capture and reverse water–gas shift reaction. • The basicity of Ni/CeO 2 promotes the CO 2 adsorption of Ni/CeO 2 -CaO in ICCU-RWGS. • Ni/CeO 2 -CaO possesses high Ni dispersion and reducibility. • Stable and even self-optimizing cyclic ICCU-RWGS performance was achieved using Ni/CeO 2 -CaO. Integrated CO 2 capture and utilisation (ICCU) is a promising strategy for restricting carbon emissions and achieving carbon neutrality. Bifunctional combined materials (BCMs), containing adsorbents and active catalysts, are widely applied in this process. Producing syngas via reverse water–gas shift reaction (RWGS) and integrating with Fischer-Tropsch (F-T) synthesis is an attractive and valuable CO 2 utilisation route. This work investigated a series of Ni/support-CaO BCMs (supports = ZrO 2 , TiO 2 , CeO 2 and Al 2 O 3) for the integrated CO 2 capture and RWGS (ICCU-RWGS) process. The Ni/support-CaO BCMs were prepared by physically mixing various metal oxide supports loaded Ni with sol–gel derived CaO. The ICCU-RWGS performance (CO 2 conversion, CO yield and CO generation rate) of these BCMs followed the order during tested conditions (550–750 °C): Ni/CeO 2 -CaO > Ni/TiO 2 -CaO > Ni/ZrO 2 -CaO > Ni/Al 2 O 3 -CaO. A comprehensive characterisation of Ni/support materials showed that Ni/CeO 2 had the characteristics of stronger basicity, optimal Ni dispersion and improved NiO reducibility, which led to the outperforming ICCU-RWGS activity over Ni/CeO 2 -CaO (e.g. 56.1% CO 2 conversion, 2.68 mmol g−1 CO yield and ∼100% CO selectivity at 650 °C). Furthermore, the Ni/CeO 2 -CaO BCM showed a stable, yet, self-optimising catalytic performance during the cyclic ICCU-RWGS reaction over 20 cycles. The TEM characterisation suggested that was ascribed to the volume expansion and shrinkage of CaO in the cyclic adsorption–desorption altering the distance between the adsorbent and Ni/CeO 2 , resulting in an enhanced CO 2 conversion during the cycle. [ABSTRACT FROM AUTHOR]

• Highly dispersed sub-nanometer Ni clusters were produced in Ni-CeO 2 /CaO. • Synergies happened between highly dispersed Ni clusters and ceria oxygen vacancies. • CH 4 productivity was 1540 mmol g−1 Ni with 50.4% of CO 2 conversion. • The dual functional materials demonstrated high stability of ICCU. Integrated carbon capture and utilization (ICCU) presents an ideal solution to address anthropogenic carbon dioxide (CO 2) emissions from industry and energy sectors, facilitating CO 2 capture and subsequent utilization through conversion into high-value chemicals, as opposed to current release into the atmosphere. Herein, we report the synergistic coupling of porous CaO, as a sorbent for CO 2 capture, and Ni doped CeO 2 nanorods, as catalytic sites for CO 2 reduction. It is found that ceria is shown to possess the capacity for CO 2 utilization, however, critically it only results in the generation of CO due to the weak CO-ceria bonding. The addition of Ni active sites gives rise to CH 4 being the predominant product, via the strong interaction between Ni species and CO, which facilitates further reduction. Through tuning Ni loadings, we have evaluated the role of catalytic active site size, with a Ni loading of only 0.5 wt% providing optimal performance through the formation of sub-nanometer sized clusters. This near-atomic active site dispersion gives rise to CH 4 productivity and selectivity of 1540 mmol g−1 Ni and 85.8%, respectively, with this optimal combination of catalyst and sorbent demonstrating high stability over 10 cycles of ICCU process. These observations in parallel with the synergistic coupling of earth-abundant, low-cost materials (CaO and Ni) will have broad implications on the design and implementation of high efficiency, cost-effective ICCU materials and processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Proposal of a new material system for the integrated CO 2 capture and utilization. • Process matching of the CO 2 desorption and in-situ dry reforming of CH 4. • Demonstration of excellent cyclic stability of ICCU-DRM using Li 4 SiO 4 sorbent. CO 2 capture and utilization has been considered as an up-and-coming short- to mid-term approach to mitigate the excessive CO 2 emission. Comparing to the conventional separate capture, transportation and conversion arrangement, the integrated CO 2 capture and utilization (ICCU) could largely simplify the complex process and reduce the energy consumption. However, the poor stability of high-temperature CO 2 sorption/desorption severely limit the potential of ICCU. Therefore, it is indispensable to develop a new sorbent/catalyst system ensuring the high-efficiency and long-term operation of the ICCU. In this paper, we propose and demonstrate the feasibility and performance of using K 2 CO 3 -doped Li 4 SiO 4 as an efficient CO 2 sorbent for ICCU operating at a relatively low temperature by dry reforming of methane. Results show that the ratio of H 2 /CO produced is stabilized at 1 ± 0.05 in the pre-breakthrough stage, and the duration extends to be 1.6 times of the original value in the cyclic operations, displaying an excellent performance in reaction matching and process stability. [ABSTRACT FROM AUTHOR]

• Toluene steam reforming to H 2 with in-situ CO 2 capture by Ni/Perovskite and CaO. • Understanding the key roles of S/C ratio and temperature during SESR of toluene. • Achievement of 90% hydrogen yield with a fraction of maximum 95% under 650 °C. • Good compatibility of Ni/Perovskite catalyst and CaO sorbent in SESR of toluene. It is known that a considerable amount of tar is usually generated in the biomass gasification process, and catalytic steam reforming is an effective method to remove this by-product. The coupling of in-situ CO 2 capture in the process can further shift the forward reforming reaction and produce hydrogen with a high purity. In this work, sorption enhanced steam reforming (SESR) of toluene (as a model compound of biomass tar) was investigated thermodynamically and experimentally using the mechanically mixed Ni/perovskite catalyst and CaO sorbent. It is verified that the appropriate temperature is 650 °C under stoichiometric reaction (S/C = 2), and around 75% average H 2 yield with a maximum H 2 purity over 95% could be obtained. Moreover, the cyclic SESR-regeneration and characterization including XRD, SEM/EDS, TEM and XPS were carried out, and it shows a stable catalytic performance and compatibility of the Ni/perovskite catalyst in the SESR process for high-purity hydrogen production. [ABSTRACT FROM AUTHOR]

The distance between catalytic sites (Ni) and sorbents (CaO) on the performance of integrated CO 2 capture and utilization (ICCU) process is crucial important because the sorbents demonstrate a dramatic volume increase during carbonation reaction (1st stage of ICCU) and sequentially cover the catalytic sites and retard the CO 2 conversion (2nd stage of ICCU). Herein, we synthesized various Ni/CaO-based dual functional materials (DFMs) with different distances between active sites and sorbents to provide different volume spaces for the growth of CaCO 3 during the carbonation reaction. It is found that both 1%NiCaO and 10%NiCaO synthesized by a one-pot method exhibited a low CO 2 conversion (38% and 45%, respectively) and CH 4 selectivity (58% and 69%, respectively) as the distance between catalytic sites and sorbents was so close that the Ni active sites were covered by the formed CaCO 3 during carbonation reaction. With the increase of the distance by physical mixing method, the CO 2 conversion and CH 4 selectivity of 1%Ni/CeO 2 -CaO-phy were largely increased to 62% and 84%, respectively at 550 °C and atmospheric pressure when captured CO 2 from 15% CO 2 /N 2. This is attributed to the fact that the Ni active sites were still well dispersed on the surface of CeO 2 nanorods instead of being covered by the newly formed CaCO 3. [ABSTRACT FROM AUTHOR]

Increasing attention has been drawn to carbon dioxide (CO 2) conversion into higher-value platform chemicals and synthetic fuels due to global warming. These reactions require a large amount of thermal energy in order to proceed, which is ascribable to the high stability of the bonds in CO 2. Non-thermal plasma (NTP)-catalytic CO 2 conversion has emerged as a promising method to significantly reduce the reaction temperature as plasma can activate CO 2 at as low as room temperature and atmosphere pressure. However, this technology requires a paradigm shift in process design to enhance plasma-catalytic performance. CO 2 conversion using plasma-catalysis has great potential to increase reaction efficiencies due to the synergetic effects between the plasma and catalysts. It is crucial to present the recent progress in CO 2 conversion and utilization whilst providing a research prospects framework and direction for future research in both industries and laboratories. Herein, a comprehensive review of recent, encouraging research achievements in CO 2 conversion using NTP is provided. The topics reviewed in this work are: i) the recent progress in different NTP sources in relation to product selectivity, conversion, and energy efficiency; ii) plasma-based CO 2 reactions and applications; iii) CO 2 conversion integrated with CO 2 capture; and iv) current challenges and future perspectives. The high market value of the possible products from this process, including chemicals and fuels, make commercialization of the process feasible. Furthermore, the selectivities of these products can be further improved by developing suitable catalysts with effective sensitivities and performances under the intricate conditions needed to make these products. There is an urgent need for further studies to be performed in this emerging field. • Non-thermal plasma is an emerging and promising technology for the conversion of CO 2. • Current technology development on CO 2 capture and conversion has been reviewed. • Plasma catalysis has great potential to generate a synergistic effect and enhance the selectivity of target products. [ABSTRACT FROM AUTHOR]

• AD digestate was converted into biochar-based sorbents of CO 2 easily. • A one-step method of introducing N into biochar was studied. • Adding urea enhanced CO 2 uptake ability of biochar. • AD digestate has potential application for carbon capture. Digestate from Anaerobic Digestion (AD) is a very common waste produced by European biogas plants and its current method of reuse is as a fertilizer or as soil amendment. This in turn however gives rise to some other environmental concerns which include greenhouse gas emissions and volatilization of ammonia causing ammonia pollution. Biochar is an environmentally friendly and low-cost product for CO 2 capture and sequestration. Thus, we have provided one simple method to convert AD digestate into biochar-based sorbents of CO 2. In addition, the nitrogen-functionalised porous carbon has been reported to be effective in improving the uptake of CO 2. However, most of them were prepared using multiple steps. In this work, N-doped biochar was prepared by a one-step method of modifying AD digestate by urea. The results show that the addition of N can increase CO 2 uptake significantly. Thus, the adsorbent modified by urea with a ratio of 1:1 results in the highest CO 2 uptake capacity (1.22 mmol g−1), indicating digestate's potential application for carbon capture and storage. [ABSTRACT FROM AUTHOR]

Biomass gasification is considered as a promising renewable energy technology to address climate change caused by greenhouse gas emissions and produce portable and clean energy products. However, biomass must be combusted in the traditional gasification to maintain the process, while excessive gasification temperature will lead to ash sintering, resulting in the shutdown of the equipment. Autothermal biomass gasification is directly maintained by carbonation reaction, which can maximize the production of combustible gas and reuse carbon dioxide in the flue gas. Lab-scale results indicated that similar H 2 yield can be obtained via Auto-CaL-Gas technology at lower operating temperatures. Moreover, H 2 concentration increased by 23.29% at 650 °C with CaO than at 750 °C without CaO, and 14.11% at 550 °C with CaO than at 650 °C without CaO, respectively, thus saving energy consumption and improving total energy efficiency in the biomass gasification process. [ABSTRACT FROM AUTHOR]