Oxidation and dissociation of formyl on Ni(111), Ni(110) and Ni(100) surfaces: A comparative density functional theory study
2014 (English)Conference paper, Published paper (Refereed)
Sustainable development
The content falls within the scope of Sustainable Development
Abstract [en]
Formyl (CHO) is an important adsorbate and a key intermediate in industrial processes such as water gas shift (WGS), Fischer Tropsch synthesis (FTS) and catalytic hydrocarbon combustion reactions. Density functional theory (DFT) with the PBE functional was used to calculate the adsorption, reaction and activation energies of formyl oxidation and dissociation on Ni(111), Ni(110) and Ni(100) surfaces. The results show that these energies are sensitive to the surface structure. The dissociation barrier for CHO → CH + O (FTS process) is higher than that for CHO → CO + H (catalytic combustion) on all three surfaces. This means that the dissociation to CO and H is kinetically favored. The dissociation reaction rate decreases in the order Ni(110) > Ni(111) > Ni(100) for both dissociation reactions. The formation of formate (CHO + O → HCOO), which is included in one of the pathways for the WGS reaction, has lowest activation energy on the Ni(111) surface, and the energy increases in the order Ni(111) < Ni(110) < Ni(100). However, the reaction rate at 463 K, which is a typical temperature for industrial processes that involve these reactions, is at least five orders of magnitude higher for the CHO → CO + H reaction than for the other two reactions, irrespective of the crystallographic structure of the Ni surface. This means that Ni surfaces studied here are better catalysts for this reaction. The results also show that the WGS reaction on a Ni catalyst does not primarily occur via the formate pathway.
Place, publisher, year, edition, pages
2014.
Keywords [en]
Nickel, Formyl, Formate, Ni(111), Ni(110), Ni(100)
National Category
Theoretical Chemistry Physical Chemistry
Research subject
Resource Recovery
Identifiers
URN: urn:nbn:se:hb:diva-7281Local ID: 2320/14472OAI: oai:DiVA.org:hb-7281DiVA, id: diva2:887993
Conference
NSC2014 - 16th Nordic Symposium on Catalysis From fundamentals to industrial application, Jun 15, 2014 - Jun 17, 2014, University of Oslo, Norway
2015-12-222015-12-222016-10-24Bibliographically approved