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Chemical looping steam reforming (CLSR) of ethanol using oxygen carriers (OCs) for hydrogen production has been considered a highly efficient technology. In this study, NiO/MgAl 2 O 4 oxygen carriers (OCs) were employed for hydrogen production via CLSR with and without CaO sorbent for in-situ CO 2 removal (sorption enhanced chemical looping steam reforming, SE-CLSR). To find optimal reaction conditions of the CLSR process, including reforming temperatures, the catalyst mass, and the NiO loadings on hydrogen production performances were studied. The results reveal that the optimal temperature of OCs for hydrogen production is 650 °C. In addition, 96% hydrogen selectivity and a 'dead time' (the reduced time of OCs) less than 1 minute is obtained with the 1 g 20NiO/MgAl 2 O 4 catalysts. The superior catalytic activity of 20NiO/MgAl 2 O 4 is due to the maximal quantity of NiO loadings providing the most Ni active surface centers. High purity hydrogen is successfully produced via CLSR coupling with CaO sorbent in-situ CO 2 removal (SE-CLSR), and the breakthrough time of CaO is about 20 minutes under the condition that space velocity was 1.908 h−1. Stability CLSR experiments found that the hydrogen production and hydrogen selectivity decreased obviously from 207 mmol to 174 mmol and 95%–85% due to the inevitable OCs sintering and carbon deposition. Finally, stable hydrogen production with the purity of 89%∼87% and selectivity of 96%∼93% was obtained in the modified stability SE-CLSR experiments. [Display omitted] • High catalytic OCs were developed via the modified Pechi method. • 20NiO/MgAl 2 O 4 attained 96% H 2 selectivity and 1 minute 'dead time' in CLSR. • The breakthrough time of CaO was 20 minutes in SE-CLSR. • Stable H 2 yield with high purity was obtained in the long-term modified SE–CLR. [ABSTRACT FROM AUTHOR]

Hydrogen production and reduction of Ni-based oxygen carriers (OCs) during chemical looping steam reforming (CLSR) of ethanol were studied in a fixed-bed reactor using four OCs with different supports including NiO/SBA-15, NiO/MCM-41, NiO/MMT and NiO/Al 2 O 3 . The OCs prepared were characterized by N 2 adsorption-desorption, TPR, TPO, XRD, TEM, FTIR and TGA-DSC. The results demonstrated that NiO component in all the OCs was first reduced by ethanol and the reduced OCs were responsible of catalytic steam reforming and water gas shift for hydrogen production. Mesoporous NiO/SBA-15 presented increasing conversion of NiO reduction and the highest selectivity of hydrogen production. The conversion of ethanol increased with reactions proceeding until the highest value is reached after about ∼300s, and the negative steam conversion obtained was resulted from H 2 O formation from ethanol oxidation by OCs. Compared with MMT and Al 2 O 3 supports, the oxidization of NiO with MCM-41 and SBA-15 supports was very fast and less carbon was formed and deposited. Enhancement in hydrogen production from CLSR process was achieved by in-situ CO 2 removal. Shrinking Core model (SCM) based on the constant pattern model for fixed-bed reactor indicated the rates of OCs reduction with ethanol were mainly controlled by surface chemical reaction and product layer diffusion. The reduction process was found to undergo three different rate-limiting stages, and the critical times for changes in the rate-limiting steps were determined. [ABSTRACT FROM AUTHOR]

A series of multifunctional catalysts were derived from lamellar montmorillonite (MMT) via ultrasound-assisted cation-exchange method. They were characterized by N 2 adsorption-desorption, X-ray diffraction (XRD), H 2 temperature-programmed reduction (H 2 -TPR), H 2 pulse chemisorption, inductively coupled plasma optical emission spectrometry (ICP-OES), and transmission electron microscopy (TEM). The characterization results show that metal-support interaction (MSI) together with Ni and Ca dispersion interrelates with confinement effect of montmorillonite. The CO 2 absorption capacity of CAT-5 (Ca/MMT molar ratio is 5) was still above 20.0% at the tenth cycle. The steam to glycerol molar ratio (S/G) and reaction temperature were investigated, and an S/G = 3 and a temperature of 600 °C were optimized. The hydrogen purity was significantly enhanced by the equilibrium shift of insitu CO 2 removal at 600 °C. CAT-5 presents the best performance considering the synchronized absorption capacity and catalytic activity. Compared with CAT-M, CAT-5 shows higher stability in the multiple reaction-decarbonation cycles, which is due to the elevated sintering resistance of CaO derived from the confinement effect of lamellar structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • SECLSR proposed realizes CO 2 in-situ capture & utilization to H 2 and syngas. • Conversion of CO 2 from in-situ extraction of dolomite using MDR at 850 °C is feasible. • NiO/NiAl 2 O 4 of 15% NiO presented good activity and stability in SECLSR and MDR. • The process is no need for separating catalyst and sorbent for SECLSR. Hydrogen production from chemical looping steam reforming using an oxygen transport catalyst is definitely enhanced by CO 2 in-situ capture, which shifts the chemical equilibrium and reduces the energy demands. The utilization of CO 2 from this process as a reactant for chemicals and fuels could help to improve economic reasons and mitigate its impact on climate. In this study, we proposed a sorption-enhanced chemical looping steam reforming of glycerol to realize the synergetic capture and conversion of CO 2 in one integrated chemical looping hydrogen production process. The process is characterized to use the oxidized NiO/NiAl 2 O 4 as a steam reforming catalyst, the reduced NiO/NiAl 2 O 4 as a CO 2 -CH 4 dry reforming catalyst, and the inexpensive dolomite as a CO 2 sorbent. The surface carbon that would deactivate the catalyst is combusted by air after CO 2 -CH 4 dry reforming and the Ni on the catalyst is re-oxidized. The coupling of these different processes of chemical looping steam reforming, CO 2 in-situ capture, dolomite decomposition and CO 2 in-situ utilization, results in simultaneous generation of high purity hydrogen and syngas. The results demonstrated that hydrogen of above 92.5% was one-step generated and CO 2 was decreased to zero in the pre-CO 2 breakthrough periods. The reduced NiO/NiAl 2 O 4 catalysts favored the CO 2 -CH 4 dry reforming at 850 °C. The syngas of H 2 -to-CO molar ratios of 0.8–1.1 through the conversion of CO 2 from in-situ extraction of the absorbed CO 2 dolomite, was produced. The NiO/Al 2 O 4 with 15 wt% NiO gave the highest hydrogen and syngas yields, and maintained high performance for the proposed system. The catalysts and dolomite exhibited good stability with no obvious loss of activity in 10 cycles. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of a series of Ni based Al-MCM-41 oxygen carriers with and without Ce promoter and their application in chemical looping steam reforming of glycerol. The Al-MCM-41 is derived from montmorillonite. The oxygen carriers were prepared by direct-synthesis and post-synthesis method. A variety of technologies including N 2 adsorption-desorption, X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), H 2 temperature-programmed reduction (H 2 -TPR), and transmission electron microscopy (TEM) were conducted to characterize the fresh and used oxygen carriers. The results show the direct-synthesis oxygen carrier possesses excellent textual properties, such as high Ni loading, small particle size, large pore volume, and uniform pore size. The incorporation of Ce could effectively control particle size via strong metal support interaction, promote the homogeneous distribution of Ni, and enhance oxygen mobility capability and water gas shift reaction. And thus shorten ‘dead time’ during the fuel feed step. The CeNi/Al-MCM-41 displayed the superior activity and excellent long-term stability, which could be due to the strengthened anti-sintering and coke capability. [ABSTRACT FROM AUTHOR]

Hydrogen production by chemical looping steam reforming of ethanol using oxygen carriers was carried out in a fixed-bed reactor. NiO/montmorillonite prepared by ultrasound assisted cation exchange impregnation method was used as oxygen carriers. The synthesized NiO/montmorillonite was characterized by N 2 adsorption–desorption, inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), transmission electron microscopy (TEM), H 2 temperature-programmed reduction (H 2 -TPR), H 2 pulse chemisorption, temperature-programmed reduction (TPO) and thermal gravimetric analysis (TGA). The characterization results showed the particle size, metal-support interaction, nickel dispersion interrelated with cation exchange capability and confinement effect of montmorillonite’s lamellar structure. Activity and stability tests were conducted at 550 °C with a steam to carbon ratio of 4. The results showed that 20Ni–MMT possessed the best performance due to its strong sintering and coking resistance, and also presented the shortest ‘dead time’ due to its larger active surface area. Moreover, 20Ni–MMT exhibited the excellent coke elimination ability in the air feed step. [ABSTRACT FROM AUTHOR]

Chemical looping steam reforming of ethanol using x CeNi/SBA-15 oxygen carriers was carried out at 650 °C under atmospheric pressure in a fixed-bed reactor. The mesoporous support SBA-15 was synthesized via hydrothermal method and the x CeNi/SBA-15 oxygen carriers were prepared by encapsulating CeO 2 and NiO nanoparticles in SBA-15 using surfactant-assisted iso-volumetric impregnation method. Some techniques were conducted to characterize the oxygen carriers, including N 2 adsorption–desorption, XRD, TEM, H 2 -TPR, ICP-OES, and DSC-TGA. It was observed that all the oxygen carriers exhibited high specific surface area (>435 m 2 /g) and large pore volume (>0.64 cm 3 /g). Small NiO particle size (e.g. 3.2 nm for 12CeNi/SBA-15), high dispersion and strengthened metal-support interaction were achieved by the CeO 2 promotion. The ceria promoter not only inhibited the coke formation but facilitated the removal of coke deposition, and the coke deposition could be further eliminated in the air feed step, both of which resulted in long-term stability. Meanwhile, superior redox performance and shorter ‘dead time’ (e.g. 30 s for 12CeNi/SBA-15) were achieved on account of easier reducibility of NiO particles with increasing amount of CeO 2 . The oxygen carriers exhibited superior sinter resistance capacity and high activity and stability in CLSR process. The highest ethanol conversion (90.0%) and hydrogen selectivity (84.7%) were obtained for 12CeNi/SBA-15 even after 14 cycle stability test. [ABSTRACT FROM AUTHOR]

This paper proposes a novel system for continuous hydrogen production from waste plastic (WP) by fluidized-bed gasification (FBG) combined sorption-enhanced steam reforming process (SERP). The system was operated in successive processes of several sections: (a) gasifying a WP into a raw gas comprising CO, H 2 , CH 4 , total hydrocarbons (THC), and small amount of HCl contaminant, etc.; (b) passing the raw gas to hydrogen production through two moving-bed reactors by continuous SERP process over Ni-based catalyst mixed CaO sorbent for in-situ CO 2 capture and HCl removal; (c) simultaneously regenerating CaCO 3 formed and catalyst with carbons deposited in other moving-bed reactor at the regeneration condition selected; and (d) carrying the particles of catalyst and sorbent to continuous steam reforming and their regeneration between two moving-bed reactors by riser. Gradually expanding chamber design of FBG reactor suitable for different particles flow to prolong the residence times of gas and solid phases makes high carbon conversion and the maximum value is up to 83.6% at 880 °C during FBG stage. The combination of FBG and SERP has produced a stream of high-purity hydrogen at some certain conditions, and about 88.4 vol % of hydrogen (H 2 O- and N 2 -free basis) was obtained at 818 °C of FBG temperature with 706–583 °C of SERP temperature. Reduced Ni-based catalyst efficiently converted raw gas from FBG and steam to H 2 , and CaO sorbent in the moving-bed reactor are capable of reducing the HCl and CO 2 to low levels at all the temperatures tested. [ABSTRACT FROM AUTHOR]

For the fixed-bed reactor configuration in the sorption-enhanced steam reforming process (SERP), solid mixture of catalyst and sorbent is stationary and alternatively exposed to reaction and regeneration conditions for multi-cycles by periodically switching the feed gases for enhanced hydrogen production with in-situ CO 2 removal. A NiO/NiAl 2 O 4 catalyst was synthesized by the co-precipitation method with rising pH technique and the crystalline spinel phase of NiAl 2 O 4 was formed under the calcination temperature of 900 °C. The catalyst was characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), thermo-gravimetric analysis (TGA), and N 2 adsorption–desorption. The non-stoichiometric thermodynamic calculation was carried out to determine the effects of temperature and in-situ CO 2 removal on the enhancement of hydrogen production by SERP from glycerol at 425–700 °C. The multi-cycles on reaction and regeneration for hydrogen production by SERP from glycerol were performed by NiO/NiAl 2 O 4 catalyst and CaO based sorbent in a fixed-bed reactor. The results showed that hydrogen production by SERP can be clearly divided into three periods, and the experimental gaseous products were compared with non-stoichiometric thermodynamic calculations. It is obvious that H 2 purity was greatly increased, and CO 2 , CO and CH 4 concentrations were reduced by in-situ CO 2 removal during the pre-breakthrough period. It is found that enhanced hydrogen production was mainly depended on in-situ CO 2 removal. The operation durations for producing high-purity hydrogen of more than 90% were decreased with the increase of the cycles. It may due to the decrease in the reactivity of CaO based sorbent after multi-cycles reaction and regeneration. [ABSTRACT FROM AUTHOR]

Integrating in-situ CO 2 removal at high temperature by solid sorbents during sorption-enhanced steam reforming process for high-purity hydrogen production has been considered to change the normal equilibrium limits of shift reactions and increase hydrocarbon conversion as well as reduce CO 2 emissions. However, a difficulty by integrating these reaction steps in a single and integrated process involves selecting suitable sorbents and reaction conditions under which all of the processes can be carried out. Due to the difficulty in application of solid sorbents in SERP, the improvement of their performance is crucial to make the process important for industrial applications. This study discussed the performances of CaO, MgO, hydrotalcite and Li 2 ZrO 3 based sorbents during sorption-enhanced steam reforming for high-purity hydrogen production, while different methods for enhancing these sorbents activities were summarized. The factors of reaction conditions such as temperature, pressure, the amount of water vapor etc. and related reaction mechanisms using these solid sorbents are identified. CaO has shown its potentials with its lost cost and high capacities. Nevertheless, the deactivation of CaO during multi-cycles carbonation-regeneration is challenging for continuous long-term operating conditions for hydrogen production from catalytic steam reforming. The potential and development of the multifunctional sorbent–catalyst materials having a dual function of catalytic steam reforming and in-situ CO 2 removal were discussed. [ABSTRACT FROM AUTHOR]

In this study, renewable hydrogen production was achieved by coupling of water splitting and glycerol oxidation reforming by chemical looping technology (CLWS-GOR) using the novel Ce–Ni modified Fe-based oxygen carriers (OCs). The OCs were developed by combining metal chelating sol-gel and isometric impregnation method, which exhibited anti-sintering characteristic and lattice oxygen migration ability in CLWS-GOR. The amount of hydrogen between 12.49 and 12.96 mmol in the steam stage was produced from all the OCs with different ratios of Fe, Ce and Ni. However, with the increase of Ce and Ni doping, the production of H 2 and CO in the fuel stage increased, as well as the probability of carbon deposits released in the subsequent steam stage. The H 2 /CO ratio in syngas were easily adjusted by steam to carbon molar ratio (S/C) in chemical looping steam reforming (CLSR), but the effects of steam introducing led to gradual deterioration of OCs. The results proved the OCs prepared by the combination method has high activity and stability for renewable hydrogen production from coupling of CLWS-GOR. [Display omitted] • Coupling of water splitting and glycerol oxidation reforming by chemical looping. • Ce–Ni modified Fe-based OCs were synthesized by combined method. • Pure H 2 was achieved from CLWS-GOR by reduced OCs. • WGS enhancement and the H 2 /CO ratio adjustment were achieved. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ni–Cu–Al catalyst for hydrogen production was synthesized by rising pH technique. [•] Experimental data were analyzed with non-stoichiometric thermodynamic calculation. [•] Catalyst deactivation due to carbon deposits in glycerol steam reforming was found. [•] Carbon removal was analyzed by TGA experiment during medium temperature oxidation. [•] Reforming was tested by separability kinetics of rate law and catalyst deactivation. [Copyright &y& Elsevier]

Abstract: The objective of this review is to analyze potential technologies and their baseline performance of producing hydrogen from catalytic steam reforming of biodiesel byproduct glycerol. High oxygen content and high impurity level of biodiesel byproduct glycerol, as well as the complex intermediates and high coking potential in its thermal degradation, make the modeling, design, and operation of glycerol steam reforming a challenge. Thermal decomposition characterization of biodiesel byproduct glycerol was covered, and the recent developments and methods for high-purity hydrogen production from glycerol steam reforming were illustrated. The thermodynamics constraint of water gas shift reaction can be overcome by the sorption-enhanced steam reforming process, which integrated catalytic steam reforming, water gas shift reaction and in-situ CO2 removal at high temperatures in a single stage reactor. The effectiveness of both the enhanced H2 production and the use of CO2 sorbents have been demonstrated and discussed. The technical challenges to achieve a stable high-purity hydrogen production by the sorption-enhanced steam reforming process included extending operation time, selecting suitable sorbents, finding a way for continuous reaction-regeneration of catalyst and sorbent mixture and improving process efficiencies. The continuous sorption-enhanced steam reforming of glycerol was designed by a simultaneous flow concept of catalyst and sorbent for continuous reaction-regeneration using two slow moving-bed reactors for high-purity hydrogen production and CO2 capture, and in this process, catalyst and sorbent were run in nearly fresh state for H2 production. The sorption-enhanced chemical-looping reforming was also demonstrated. The paper discusses some issues and challenges, along with the possible solutions in order to help in efficient production of hydrogen from catalytic steam reforming of biodiesel byproduct glycerol. [Copyright &y& Elsevier]

In this study, the continuous sorption-enhanced steam reforming of glycerol to high-purity hydrogen production by a simultaneous flow concept of catalyst and sorbent for reaction and regeneration using two moving-bed reactors has been evaluated experimentally. A Ni-based catalyst (NiO/NiAl2O4) and a lime sorbent (CaO) were used for glycerol steam reforming with and without in-situ CO2 removal at 500 °C and 600 °C. The simultaneous regeneration of catalyst and sorbent was carried out with the mixture gas of N2 and steam at 900 °C. The product gases were measured by a GC gas analyzer. It is obvious that the amounts of CO2, CO and CH4 were reduced in the sorption-enhanced steam reforming of glycerol, and the H2 concentration is greatly increased in the pre-CO2 breakthrough periods within 10 min both 500 °C and 600 °C. The extended time of operation for high-purity hydrogen production and CO2 capture was obtained by the continuous sorption-enhanced steam reforming of glycerol. High-purity H2 products of 93.9% and 96.1% were produced at 500 °C and 600 °C and very small amounts of CO2, CH4 and CO were formed. The decay in activity during the continuous reaction-regeneration of catalyst and sorbent was not observed. [ABSTRACT FROM AUTHOR]

Abstract: About 10wt.% of glycerol can be produced during the conversion of vegetable oils or animal fats into biodiesel fuel by the transesterification process. To make use of glycerol and increase its values, H2 production from catalytic steam reforming of glycerol by Ni–Mg–Al based catalysts was evaluated experimentally in a fixed-bed reactor under atmospheric pressure within a temperature range of 450–650°C. The thermodynamic analysis was conducted by using a non-stoichiometric methodology based on the minimization of Gibbs free energy. The Ni–Mg–Al based catalysts were synthesized by the co-precipitation method with rising pH technique. The synthesized catalysts were characterized by the elemental analysis, BET, XRD and SEM methods. All the metals in the catalyst remained in oxide forms and the catalysts had the specific surface areas from 98.542 to 126.777m2/g for different compositions. The results showed that glycerol conversion and H2 selectivity were increased with increasing temperatures from 450 to 650°C. The formations of CH4 and CO in the glycerol steam reforming were almost negligible. Carbon formation in glycerol steam reforming was serious in low temperatures. The catalyst containing NiO of 24.1wt.%, MgO of 26.1wt.% and Al2O3 of 49.8wt.% performed appreciable catalytic activity, and the H2 selectivity was found to be 78.5% and conversion of glycerol was up to 88.0% at 650°C. The effects of the operating conditions including temperature, the ratio of steam to carbon (S/C), glycerol inlet concentration and flow rate of carrier gas on glycerol steam reforming by the optimized catalyst were tested. Based on a kinetic model assuming the power law with a first reaction order, the activation energy and the frequency factor for glycerol steam reforming by the Ni–Mg–Al based catalysts were calculated. [Copyright &y& Elsevier]

Abstract: Hydrogen production from steam reforming of glycerol in a fluidized bed reactor has been simulated using a CFD method by an additional transport equation with a kinetic term. The Eulerian–Eulerian two-fluid approach was adopted to simulate hydrodynamics of fluidization, and chemical reactions were modelled by laminar finite-rate model. The bed expansion and pressure drop were predicted for different inlet gas velocities. The results showed that the flow system exhibited a more heterogeneous structure, and the core-annulus structure of gas–solid flow led to back-mixing and internal circulation behaviour, and thus gave a poor velocity distribution. This suggests the bed should be agitated to maintain satisfactory fluidizing conditions. Glycerol conversion and H2 production were decreased with increasing inlet gas velocity. The increase in the value of steam to carbon molar ratio increases the conversion of glycerol and H2 selectivity. H2 concentrations in the bed were uneven and increased downstream and high concentrations of H2 production were also found on walls. The model demonstrated a relationship between hydrodynamics and hydrogen production, implying that the residence time and steam to carbon molar ratio are important parameters. The CFD simulation will provide helpful data to design and operate a bench scale catalytic fluidized bed reactor. [ABSTRACT FROM AUTHOR]

Abstract: Steam reforming of the crude glycerol by-product of a biodiesel production plant has been evaluated experimentally at atmospheric pressure, with and without in situ CO2 sorption, in a continuous flow fixed-bed reactor between 400°C and 700°C. The process outputs were compared to those using pure glycerol. Thermodynamic equilibrium calculations were used to assess the effect on the steam reforming process of the main crude impurities (methanol and four fatty acid methyl esters). The crude glycerol and steam conversions and the H2 purity reached 100%, 11% and 68%, respectively at 600°C. No CH4 was found at and above 600°C. Steam reforming of crude glycerol with in situ CO2 removal is shown to be an effective means of achieving hydrogen purity above 88% in pre-CO2 breakthrough conditions. [Copyright &y& Elsevier]

[Display omitted] • Hydrogen was efficiently produced from CLSR of biodiesel byproduct glycerol. • Well-order mesoporous CeNiO/MCM-41 and CeNiO/SBA-15 were synthesized for CLSR. • High feeding conversion and H 2 selectivity was achieved by mesoporous OCs. • High loading NiO and CeO 2 on mesoporous OCs achieved excellent CLSR redox cycles. The selection of metal oxides and supports to improve catalytic activity and stability of oxygen carriers (OCs) is crucial for chemical looping steam reforming (CLSR) to hydrogen production. In this study, the Ni-based MCM-41 and SBA-15 OCs with and without CeO 2 promoter were prepared by direct synthesis and impregnation methods. The BET, XRD, TEM, ICP-AES, H 2 -TPR and DSC-TGA were used to analyze the synthesized OCs. Hydrogen production by CLSR using biodiesel byproduct glycerol was studied in a fixed-bed reactor with fuel and air stages. The DSC-TGA experiments were carried out to determine the thermal decomposition of biodiesel byproduct glycerol and the results indicated the exothermic and/or endothermic reactions as a result of secondary reactions and, the main degradation with the mass loss of 85.5 wt% occurred in the stages of 150–500 °C. The mesoporous OCs presented high specific surface area, large pore volume, and uniform pore size. It was found that the NiO and CeO 2 in the mesoporous OCs were first reduced by fuels and the reduced OCs was responsible of steam reforming and water gas shift (WGS) to hydrogen production, and hydrogen selectivity was up to 90% using CeNiO/SBA-15. The mesoporous OCs with Ce promoter greatly shortened 'dead time' (the reduce time of OCs), and effectively suppressed carbon deposited on OCs. High loading of NiO and CeO 2 on SBA-15 improved oxygen transfer and achieved excellent cyclic stability. These findings provide the fundamental understanding and principle of design on the conventional Ni-based OCs with room for further developments in chemical looping process. [ABSTRACT FROM AUTHOR]

In this study, a critical comparison between two low metal (Ni) loading catalysts is presented, namely Ni/Al2O3 and Ni/AlCeO3 for the glycerol steam reforming (GSR) reaction. The surface and bulk properties of the catalysts were evaluated using a plethora of techniques, such as N2 adsorption/desorption, Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP–AES), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDX, Transmission Electron Microscopy (TEM), CO2 and NH3– Temperature Programmed Desorption (TPD), and Temperature Programmed Reduction (H2–TPR). Carbon deposited on the catalyst's surfaces was probed using Temperature Programmed Oxidation (TPO), SEM, and TEM. It is demonstrated that Ce-modification of Al2O3 induces an increase of the surface basicity and Ni dispersion. These features lead to a higher conversion of glycerol to gaseous products (60% to 80%), particularly H2 and CO2, enhancement of WGS reaction, and a higher resistance to coke deposition. Allyl alcohol was found to be the main liquid product for the Ni/AlCeO3 catalyst, the production of which ceases over 700 °C. It is also highly significant that the Ni/AlCeO3 catalyst demonstrated stable values for H2 yield (2.9–2.3) and selectivity (89–81%), in addition to CO2 (75–67%) and CO (23–29%) selectivity during a (20 h) long time-on-stream study. Following the reaction, SEM/EDX and TEM analysis showed heavy coke deposition over the Ni/Al2O3 catalyst, whereas for the Ni/AlCeO3 catalyst TPO studies showed the formation of more defective coke, the latter being more easily oxidized. [ABSTRACT FROM AUTHOR]

Algae species like Schizochytrium sp. are resilient photosynthetic factories that produce large quantities of fatty acids that can be converted to biodiesel. These lipids must be extracted from the raw biomass before they can be used as biofuel feedstocks or other bioproducts such as hydrogen. In this paper, hydrogen production by steam reforming of schizochytrium algae oil are studied. The effects of continuous microwave and intermittent microwave, freezing and thawing times of different mass fractions, time of alkali heat and other factors on the ratio of cell disruption and ultrasonic-assisted ethanol extraction are considered. The results show that the highest lipid yield can reach by ultrasonic-assisted ethanol extraction from the schizochytrium algae which are pretreated by alkali heat method. The hydrogen production from steam reforming of the lipids, which are extracted by ethanol with ultrasonic-assisted from algae after alkali thermal pretreated is proposed. • Hydrogen produced by steam reforming of Schizochytrium algae oil. • Algae oil extracted by ethanol with ultrasonic-assisted from pretreated algae. • Algae pretreated by potassium hydroxide at 60 °C. [ABSTRACT FROM AUTHOR]