A study on characterization and methane dry reforming performance of Co-Ce/ZrO2 catalyst

The overall purpose of this study is to propose an effective Co-based non-PGM bimetallic carbon dioxide reforming of methane (CDRM) catalyst, and to find the optimal reaction conditions to be used in production of synthesis gas. In catalyst formulation, ZrO2, which has ability to produce surface oxygen, is used as a support. Ce is used as a promoter in order to increase oxygen storage capacity and to regulate surface oxygen transfer. Freshly reduced and spent catalysts were analyzed by SEM-EDX, HRTEM-EDX, TPO, Raman Spectroscopy and XPS. The reaction conditions were optimised through the use of an experimentally designed procedure using reaction temperature, CH4/CO2 feed ratio and space velocity as the parameters. XPS analysis of Co 2p indicated that additional oxidation of Co was limited during CDRM which may only lead to a small decrease in activity. EM measurements showed well dispersion of Co and Ce on the surface. No significant metal sintering was observed. Local changes in Co/Ce ratio were found to have pronounced effect on carbon formation. It is well known that methane dehydrogenation produces surface carbon as the side product covering the active site. The comparative analysis of extent of carbon coverage on Co and Ce sites of the freshly reduced and spent samples through metal mapping by SEM-EDX indirectly confirmed methane dehydrogenation is the primary function of Co sites, and there is no methane activation on Ce sites. A comparative evaluation of XPS Ce 3d obtained from freshly reduced and spent samples on the other hand showed the surface oxygen storage/transfer function of Ce through redox cycle. In the performance tests, high activity with stable performance was observed for 1/1CH(4)/CO2 feed ratio for CDRM over Co-Ce/ZrO2 catalyst. (C) 2014 Elsevier B.V. All rights reserved.