Strain in Silica-Supported Ga(III) Sites : Neither Too Much nor Too Little for Propane Dehydrogenation Catalytic Activity
Praveen, C. S. (ETH Zürich. Department of Chemistry and Applied Biosciences)
Borosy, A. P. (ETH Zürich. Department of Chemistry and Applied Biosciences)
Copéret, Christophe (ETH Zürich. Department of Chemistry and Applied Biosciences)
Comas-Vives, Aleix (Universitat Autònoma de Barcelona. Departament de Química)

Data:	2021
Resum:	Well-defined Ga(III) sites on SiO are highly active, selective, and stable catalysts in the propane dehydrogenation (PDH) reaction. In this contribution, we evaluate the catalytic activity toward PDH of tricoordinated and tetracoordinated Ga(III) sites on SiO by means of first-principles calculations using realistic amorphous periodic SiO models. We evaluated the three reaction steps in PDH, namely, the C-H activation of propane to form propyl, the β-hydride (β-H) transfer to form propene and a gallium hydride, and the H-H coupling to release H, regenerating the initial Ga-O bond and closing the catalytic cycle. Our work shows how Brønsted-Evans-Polanyi relationships are followed to a certain extent for these three reaction steps on Ga(III) sites on SiO and highlights the role of the strain of the reactive Ga-O pairs on such sites of realistic amorphous SiO models. It also shows how transition-state scaling holds very well for the β-H transfer step. While highly strained sites are very reactive sites for the initial C-H activation, they are more difficult to regenerate. The corresponding less strained sites are not reactive enough, pointing to the need for the right balance in strain to be an effective site for PDH. Overall, our work provides an understanding of the intrinsic activity of acidic Ga single sites toward the PDH reaction and paves the way toward the design and prediction of better single-site catalysts on SiO for the PDH reaction. We performed computational calculations of Ga(III) single sites on realistic amorphous models of SiO to evaluate their catalytic activity toward the propane dehydrogenation reaction. Our results show that a balance in strain is key, in which neither too stiff nor too loose Ga−O bonding is needed to obtain the highest catalytic activity.
Ajuts:	Ministerio de Economía, Industria y Competitividad RYC-2016-19930 Agencia Estatal de Investigación PGC2018-100818-A-I00
Nota:	Altres ajuts: acords transformatius de la UAB
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Publicat a:	Inorganic chemistry, Vol. 60, Issue 10 (May 2021) , p. 6865-6874, ISSN 1520-510X

DOI: 10.1021/acs.inorgchem.0c03135
PMID: 33545002

10 p, 4.2 MB

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