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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]

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]