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[Display omitted] • Ni-based catalysts supported by mesoporous CeO 2 were successfully prepared for GDR. • Thermodynamic study of GDR was carried out to compare the experimental data. • 5Ni/CeO 2 presented the highest activity with glycerol conversion of 84.1% at 750℃. • Ni loading ratio of 5 could reduce the generation of filamentous carbon during GDR. In this paper, the mesoporous Ni/CeO 2 catalyst with high specific surface area was prepared by the colloidal solution combustion method and used for the production of syngas by glycerol dry reforming (GDR). The thermodynamic analysis was conducted by using a non-stoichiometric methodology based on the minimization of Gibbs's free energy. The characterization results show that the higher the Ni content, the weaker the interaction between Ni and the CeO 2 support. 5Ni/CeO 2 shows the most consistent Ni dispersion and uniform particle size, and it has the best catalytic activity in the GDR and the conversion of glycerol can reach 84.1 % at 750 °C. Besides, all catalysts exhibited excellent stability during the 10 h catalytic process. The temperature-programmed oxidation (TPO) results show that Ni loading ratio of 5 can reduce the production of filamentous carbon. Based on a kinetic model assuming a power law as a first-order reaction, the activation energy of the Ni-based catalyst for glycerol dry reforming was calculated. [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]

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]

[Display omitted] • Mesoporous Ni-Cu/CeO 2 was successfully synthesized to APR of biodiesel byproduct glycerol. • 1Ni2Cu/CeO 2 presented superior activity and multi-cycle stability in APR. • Cu element in catalysts effectively improved WGS and inhibited CH 4 formation. • Enhanced WGS and reduced methanation were achieved by in-situ CO 2 removal. Aqueous phase reforming (APR), regarded as one method for inexpensive H 2 production, was widely studied due to lower temperature and unnecessary to vaporize water and fuels. In this study, the mesoporous CeO 2 , regarded as a metal oxide carrier, was first prepared by colloidal solution combustion, and then the Ni-Cu bimetallic supported on mesoporous CeO 2 was successfully synthesized to investigate the catalytic performance in APR of biodiesel byproduct glycerol. The results show that the Cu element in the catalysts can effectively improve water–gas shift (WGS) reaction and inhibit the formation of methane, which increases the H 2 production rate from 125.08 to 195.57 µmol⋅min−1⋅g cat−1. The higher reaction temperature is beneficial to the H 2 production rate, but not to H 2 selectivity. Kinetics analysis indicates that catalyst of 1Ni2Cu/CeO 2 + 0.2gCaO has the lowest apparent activation energy (29.86 kJ⋅mol−1). CaO is introduced as an absorbent to improve WGS reaction and reduce methanation reactions through in-situ CO 2 removal and capture. The reaction path and mechanism of APR of glycerol are also discussed in this paper. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the pyrolysis characteristics of sucrose biomass were investigated in a tubular reactor at different temperatures and also using a thermogravimetric analyzer at the heating rate of 10°Cmin−1 from room temperature to 1200°C. The gas products in the pyrolysis process were measured using an Agillent 6890N GC analyzer. The results showed that the temperature greatly affected the product yields. The pyrolysis gas consisted of a major amount of CO, CO2, H2, and CH4, and its yield increased greatly with increasing temperature. Tars occurred mainly at 200–300°C under isothermal measurements in tubular reactor. The amounts of solid residue and tars decreased with increasing temperature. The presence of CaO responsible for the pyrolysis phase was shown to increase the conversion of sucrose and capture the CO2 produced. The kinetic analysis indicated that the reaction order model (first order) predicted accurately the conversion of 0.102–0.901 during the isothermal pyrolysis of sucrose in tubular reactor, and Arrhenius parameters and prediction of the pyrolysis time were obtained from isothermal kinetic results. [Copyright &y& Elsevier]

[Display omitted] • Correlation between biochar oxidation reaction (BOR) and electrolytes was determined. • Alkaline electrolyte was more favorable for biochar-assisted water electrolysis. • The higher concentration of H 2 SO 4 and S O 4 2 - slowed down the BOR kinetics. • The highest diffusion coefficient of 3.11 × 10−3 cm2∙s−1 for biochar was obtained at pH of 13.98. Biochar-assisted water electrolysis (BAWE) for hydrogen production is employed to reduce energy consumption by replacing the oxygen evolution reaction (OER) with thermodynamically more favorable biochar oxidation reaction (BOR). Electrolyte, as a carrier to dissolve the biochar particles and form conductive solution, is essential for the transfer and transformation of biochar particles and free radical precursors. Herein, the effects of electrolyte type, concentration, and pH on the BOR performance of BAWE system were investigated. Results show that 1 M KOH solution as an electrolyte was more suitable for the BAWE system, and the BOR of the alkaline BAWE system had the higher electrochemical activity (E 10 = 1.649 V vs RHE, 56 mV∙dec−1) compared with the OER in conventional water electrolysis system (E 10 = 1.982 V vs RHE, 189 mV∙dec−1). The anion adsorption phenomenon appeared in acidic media restricted the BOR kinetics. In addition, the diffusion coefficient of anodic reaction components showed a first decrease and then increase trend when the pH increased. And the diffusion coefficient reached the maximum value of 3.11 × 10−3 cm2∙s−1 at pH of 13.98, which was favorable for accelerating the diffusion of reaction components from the bulk solution to the electrode surface. This work can provide guidance for further improving the diffusion of reaction components, the biochar oxidation rate and hydrogen production in BAWE process. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of a series of x CeNi-PSNT (phyllosilicate nanotube) oxygen carriers (OCs) and presents the effect of Ce loading on the performance in chemical looping reforming (CLR) of glycerol. Various characterization techniques including N 2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), H 2 temperature-programmed reduction (TPR), X-ray photoelectron spectra (XPS) and O 2 volumetric chemisorption were employed to investigate the physicochemical properties of the fresh and used OCs. The characterization results demonstrated that the PSNT structure possessed strong confinement effect and that the Ce promotion improved Ni dispersion and the reducibility of NiO particle and isolated Ni ions. The enhanced reducibility significantly shortened the dead time in the fuel feed step, resulting in the high H 2 generation efficiency. The reactivity and stability tests were conducted in a fixed-bed reactor. A Ce/Ni mass ratio of 0.5 was optimized for CLR with an average H 2 yield of 12.5 wt%, an average NiO conversion of 67%, and an accumulated coke deposition of 3.8 wt% in a 10-cycle stability test. The confinement effect of PSNT and Ce promotion both have positive effects on attaining the excellent performance. [ABSTRACT FROM AUTHOR]