Akademik Veri Yönetim Sistemi
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, cilt.46, sa.77, ss.38281-38298, 2021 (SCI-Expanded)
Highly ordered mesoporous gamma-Al2O3 particles and MgO materials were synthesized by evaporation induced self-assembly (EISA) and template-free hydrothermal co-precipitation routes, respectively. Ni, Ni-MgO, and Ni-La2O3-containing catalysts were prepared using a wet-impregnation method. The synthesized catalysts were characterized by N-2 adsorption -desorption, XRD, SEM-EDS, DRIFTS, XPS, TGA-DTA, and Raman spectroscopy analysis. The mesoporous gamma-Al2O3 catalyst support exhibited a high surface area of 245 m(2)/g and average pore volume of 0.481 cm(3)/g. The DRIFTS results indicate the existence of large Lewis's acid regions in the pure gamma-Al2O3 and metal-containing catalysts. Catalytic activity tests of pure materials and metal-containing catalysts were carried out at the reaction temperature of 750 degrees C and a feed molar ratio of AA/H2O/Ar:1/2.5/2 over 3 h. Complete conversion of acetic acid and 81.75% hydrogen selectivity were obtained over the catalyst 5Ni@gamma-Al2O3. The temperature and feed molar ratio had a noticeable impact on H-2 selectivity and acetic acid conversion. Increasing the water proportion in the feed composition from 2.5 to 10 considerably improved the catalytic activity by increasing hydrogen selectivity from 81.75% to 91%. Although the Ni-based gamma-Al2O3 -supported catalysts exhibited higher activity performance compared to the Ni-based MgO-supported catalysts, they were not as resistant to coke formation as were MgO-supported catalysts. The introduction of MgO and La2O3 into the Ni@gamma-Al2O3 and Ni@MgO catalysts' structures played a significant role in lowering the carbon formation (from 37.15% to 17.6%-12.44% and 12.17%, respectively) and improving the thermal stability of the catalysts by decreasing the agglomeration of acidic sites and reinforcing the adsorption of CO2 on the catalysts' surfaces. Therefore, coke deposition was reduced, and catalyst lifetime was improved. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.