Issue 13, 2017

Mechanistic insights into complete hydrogenation of 1,3-butadiene over Pt/SiO2: effect of Pt dispersion and kinetic analysis

Abstract

Gas-phase hydrogenation of 1,3-butadiene was investigated over Pt/SiO2 catalysts with the aim of understanding the complete hydrogenation of dienes. The measurements focused on the effect of Pt dispersion on the product distribution and the kinetics of n-butane formation. Under the investigated conditions with an excess of hydrogen, the selectivity to n-butane sharply decreased from 41.6% to less than 3% at a 1,3-butadiene conversion of ∼10% when the average Pt particle size increased from 3.9 to 22 nm. Correspondingly, the apparent activation energy for n-butane formation was measured to increase by about 2.7 times. In situ diffuse reflectance infrared Fourier transform (DRIFT) observations via alternating 1,3-butadiene and hydrogen feeds over the catalysts demonstrated that 1-butene was the major reaction intermediate in the process of 1,3-butadiene hydrogenation. By analysis of the kinetic data using the Horiuti–Polanyi mechanism with 1-butene as the intermediate, different reactivities of hydrogen on the catalysts towards C[double bond, length as m-dash]C bond hydrogenation were proposed to understand the variation of the selectivity to n-butane with Pt dispersion. This viewpoint was further supported by DFT calculation of 1-butene hydrogenation with hydrogen at different sites on the Pt(111) surface.

Graphical abstract: Mechanistic insights into complete hydrogenation of 1,3-butadiene over Pt/SiO2: effect of Pt dispersion and kinetic analysis

Article information

Article type
Paper
Submitted
21 جمادى الثانية 1438
Accepted
14 شعبان 1438
First published
15 شعبان 1438

Catal. Sci. Technol., 2017,7, 2717-2728

Mechanistic insights into complete hydrogenation of 1,3-butadiene over Pt/SiO2: effect of Pt dispersion and kinetic analysis

C. Hu, J. Sun, D. Kang, Q. Zhu and Y. Yang, Catal. Sci. Technol., 2017, 7, 2717 DOI: 10.1039/C7CY00534B

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