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Croatica Chemica Acta, Vol. 93 No. 2, 2020.

Original scientific paper

https://doi.org/10.5562/cca3649

Role of the Various Surface Sites and Species in CO Hydrogenation Over Alumina-supported Co-Pd Catalysts

Maya G. Shopska orcid id orcid.org/0000-0002-9714-2464 ; Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bldg. 11, 1113 Sofia, Bulgaria
Iskra Z. Shtereva ; Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bldg. 11, 1113 Sofia, Bulgaria
Hristo G. Kolev ; Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bldg. 11, 1113 Sofia, Bulgaria
Krasimir K. Tenchev ; Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bldg. 11, 1113 Sofia, Bulgaria
Silviya Z. Todorova ; Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bldg. 11, 1113 Sofia, Bulgaria
Georgi B. Kadinov ; Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bldg. 11, 1113 Sofia, Bulgaria

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Abstract

The paper is focused on evaluation of active centres and impact of adsorbed species on (10%Co+0.5%Pd)/Al2O3 catalyst system performance aiming selectivity optimization. Application of different sets of precursor pretreatment and reduction resulted in catalysts exhibiting high CO conversion or high methane selectivity. A sample of high selectivity was prepared by pretreatment in hydrogen and the performance was determined by lower amount of strongly adsorbed CO, strongly adsorbed carbonate species, and higher amount of reduced metal and bimetallic particles. A more active system was formed by pretreatment in air leading to larger amount of unreduced metal and CO-bridged species on the surface, stable coverage of hydroxyl groups on the support, and medium-strength sites for adsorption of carbonates. Ratios of hydrogen to carbon monoxide adsorption (H/СО) and of strongly to weakly adsorbed СО species appeared as important criteria for catalyst efficiency together with supported metal state, amount of unreduced ions, bimetallic particle formation, and alumina’s ability to adsorb CO and CO2.

This work is licensed under a Creative Commons Attribution 4.0 International License.

Keywords

Co-Pd catalysts; CO hydrogenation; H2 and CO chemisorption; in situ DRIFTS; surface sites; adsorbed species; activity; selectivity; TPR; TPD; XPS

Hrčak ID:

247328

URI

https://hrcak.srce.hr/247328

Publication date:

11.10.2020.

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