Understanding of the structure activity relationship of PtPd bimetallic catalysts prepared by surface organometallic chemistry and ion exchange during the reaction of iso-butane with hydrogen

Reem A. Al-Shareef, Moussab Harb, Youssef Saih, Samy Ould-Chikh, Manuel A. Roldan, Dalaver H. Anjum, Elodie Bile Guyonnet, Jean-Pierre Candy, Deng-Yang Jan, Suheil F. Abdo, Antonio Aguilar-Tapia, Olivier Proux, Jean-Louis Hazemann, Jean-Marie Basset

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6 Scopus citations

Abstract

Well-defined silica supported bimetallic catalysts Pt100-x Pdx were prepared by Surface Organometallic Chemistry (SOMC) and Ionic-Exchange (IE) methods. For all investigated catalysts, iso-butane reaction with hydrogen under differential conditions led to the formation of methane and propane, n-butane, and traces of iso-butylene. The total reaction rate decreased with increasing the Pd loading for both catalysts series as a result of decreasing turnover rate of both isomerization and hydrogenolysis. In the case of Pt100-x Pdx(SOMC) catalysts, the experimental results in combination with DFT calculations suggested a selective coverage of Pt (1 0 0) surface by agglomerated Pd atoms like “islands”, assuming that each metal roughly keeps its intrinsic catalytic properties with relatively small electron transfer from Pt to Pd in the case of Pt-rich sample and from Pd to Pt in the case of Pd-rich sample. For the PtPd catalysts prepared by IE, the catalytic behavior could be explained by the formation of a surface alloy between Pt and Pd in the case of Pd-rich sample and by the segregation of a small amount of Pd on the surface in the case of Pt-rich sample, as demonstrated by TEM, EXAFS and DFT. The catalytic results were explained by a structure activity relationship based on the proposed mechanism of CH bond and CC bond activation and cleavage for iso-butane hydrogenolysis, isomerization, cracking and dehydrogenation.
Original languageEnglish (US)
Pages (from-to)34-51
Number of pages18
JournalJournal of Catalysis
Volume363
DOIs
StatePublished - Apr 25 2018

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