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Theoretical study of Au/SAPO-11 catalyst and its potential use in thiophene HDS

Abstract:

Quantum chemistry calculations were carried out, using ONIOM2 methodology, in order to investigate the thiophene interaction with gold supported on silicoaluminophospates molecular sieves (Au/SAPO-11) catalysts. Two models were studied, one containing one Au atom per site, and the other with two Au atoms per site. Thiophene adsorption was found to be η<sup>1</sup> type. This adsorption presents a ΔH of -13.2 and -9.7 kcal/mol, for the models with one Au atom (Au/SAPO-11), and two Au atoms (Au<inf>2</inf>/SAPO-11), respectively. The partial hydrogenation of the thiophene-Au/SAPO-11 and thiophene-Au<inf>2</inf>/SAPO-11 complexes gives 2,5-dihydrothiophene (DHT), with a ΔH of -23.0 and -36.8 kcal/mol, respectively. 2-Butene production was found in both models with further hydrogenation. Likewise the direct butadiene elimination is achieved, but only with the separated Au dimer (ΔH = -17.5 kcal/mol). © 2009 Elsevier B.V. All rights reserved.