In situ AP-XPS and XANES of Co-Based Catalysts during Ethanol Steam Reforming

CARLOS ESCUDERO; CRISTIÁN HUCK IRIART; LLUIS SOLER; ALBERT CASANOVAS; CARLO MARINI; JORDI PRAT; JORDI LLORCA PIQUÉ

Berlin

Workshop; 5th Annual APXPS Workshop; 2018

The Ethanol Steam Reforming (ESR) reaction is a well-known process used for hydrogen generation and especially interesting for the on-site production of this gas. Three different Co-based catalysts have been studied for the ESR reaction using in situ Near Ambient Pressure XPS (NAP-XPS) and X-ray Absorption Near Edge Structure (XANES) at the ALBA Synchrotron Light Source. The Co-based catalysts studied are Co3O4 (Co-spinel), Co3[Si2O5]2(OH)2 (Co-talc) and [Co2Mg4Al2(OH)16]CO3·4H2O (Co-hydrotalcite or Co-HT). The use of Cobalt-based catalysts allows decreasing the reaction temperature since there is no methane generation in the intermediate reaction steps as opposed to other catalysts that do produce this gas, which can only be reformed at high temperature. Furthermore, the possibility to operate at lower temperatures shifts the water-gas shift reaction balance towards the formation of hydrogen. However, Co-based catalysts can be deactivated under ESR reaction conditions due to carbon deposition and this fact has been attributed to the formation of metallic Co [1]. Our recently published results [2] show that when using Co-spinel and Co-talc for ESR metallic Co is detected while for Co-HT, which exhibits an excellence performance for ESR, there is no formation of metallic Co. This interesting result allows designing cobalt-based catalysts for ESR without coke deposition by placing in appropriate environments Coδ+ active species.