The mechanism of the water dissociation and dehydrogenation of glycerol on Au (111) and PdAu alloy catalyst surfaces. (1st September 2021)

• Record Type: Journal Article
• Authors: Karim, N.A.; Alias, M.S.; Kamarudin, S.K.
• Is Part Of: International journal of hydrogen energy. Volume 46:Number 60(2021)
• Page Start: 30937
• Page End: 30947
• Publication Date: 2021-09-01
• Subjects: PdAu alloy catalysts -- Surface reaction -- Water splitting -- Dehydrogenation -- Glycerol; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2021.05.009
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Hydrogen is an energy carrier found from renewable sources such as biomass, geothermal, solar, or wind. Water splitting and dehydrogenation of glycerol is a sustainable process of H2 production from renewables because water is abundant, and the glycerol is formed from the biomass-derived compounds. However, finding a suitable and best catalyst for these processes is challenging. Thus, this paper proposed a theoretical study to find the mechanism of the dissociation of water and dehydrogenation of glycerol using Au metal and PdAu alloy catalysts using the density functional theory (DFT) method. Four PdAu alloys have been constructed with different atomic compositions ranging from 1 to 3 of Pd metal to Au metal. The result showed strong adsorption on the Pd1 Au3 catalyst surface, and the water splitting is best on the Pd3 Au1 catalyst surface. Simultaneously, the glycerol adsorption on catalyst surfaces is tested before proceeding for the complete dehydrogenation mechanism of glycerol. Strong adsorption was found at the Pd1 Au3 catalyst compared to other catalyst surfaces on the glycerol adsorption. The dehydrogenation mechanism was found toward a downhill reaction and removed eight hydrogens from the glycerol compared to Au metal, referring to easy dehydrogenation of glycerol using the alloy PdAu. The final species that adsorbed on the Pd1 Au3 surface is the carbon monoxide will be turned later into carbon dioxide. Highlights: The density functional theory method is use to determine the mechanism of water dissociation and dehydrogenation of glycerol. The water molecule is strongly adsorbed on the Pd1 Au3 catalyst surface, but water dissociation is the best on the Pd3 Au1 surface. The mechanism reaction energy for dehydrogenation on PdAu alloy is lower than Au catalyst leads to better hydrogen production. Moderate CO adsorption on Pd1 Au3 can reduce the catalyst poisoning problem.