Effects of simultaneous calcination and reduction on performance of promoted Ni/SiO_2 catalyst in steam reforming of propane

摘要

The effects of distinct and simultaneous calcination and reduction (DCR & SCR) processes were determined over 10Ni/SiO2 catalyst. The results showed that the C3H8 conversion and H-2 yield increased from 69% to 51% for DCR to 91% and 64% for SCR catalyst. Calcination before reduction seemed to be resulting in the construction of larger Ni particles and it may be due to partial phyllosilicates decomposition. According to the initial tests, to elevate the C3H8 conversion and H-2 yield, the effects of promoters such as La, Ce, K, and Sr were examined on the catalyst performance. Activity test illustrated that K and Sr declined the propane conversion and H-2 yield, however, Ce and La increased them. Synthesized catalysts were characterized using XRD, BET, H-2-TPR, SEM, and TGA/DTA to determine the structural properties. Consistent with BET and XRD analysis, K and Sr had the low surface area and large Ni crystallite size, contributing to coke deposition on the catalyst surface. Among the promoted samples, La-containing catalyst showed good activity and then, in the rest of this work, 10Ni-yLa/SiO2 (y = 2, 5, 8 wt%) catalysts were examined. The results showed that 10Ni-2La/SiO2 catalyst improved the particle dispersion and decreased the particle size so that specific surface area and porous volume were maximized and minimized, respectively. 10Ni-2La/SiO2 catalyst at GHSV of 45000 (ml/h.g(cat)), the temperature of 640C, and S/C = 3 in 420 min time-on-stream showed the best performance, that is C3H8 conversion of 95% and H-2 yield of 69% in propane steam reforming (PSR). (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.