Supported bimetallic PtNi-vinyl complex for hydrosilylation of straight-chain terminal alkenes with tertiary silanes: Effect of Ni promoter on catalytic performance

Abstract

A bimetallic PtNi-vinyl complex as catalytic active center was created on modified rice straw biochar by introducing an appropriate amount of cheap Ni component as a catalytic promoter. The constructed bimetallic catalyst (PtNi-VTES-RSOC) was used to catalyze hydrosilylation of terminal alkenes with tertiary silanes to produce alkylsilanes with high commercial application value. The experimental results proved that the conversion of 1-octene 96.5 % and selectivity for target product 97.1 % were obtained in hydrosilylation of 1-octene with triethoxysilane catalyzed by PtNi-VTES-RSOC with mass ratio of Pt/Ni = 1.5:1 (molar ratio of Pt/Ni≈1:2) under mild conditions (atmospheric pressure, solvent-free, 50 ℃ and 3 h). It also possessed higher catalytic ability and regioselectivity for hydrosilyation of long-chain alkenes (1-octadecene) with tertiary silanes compared to the counterpart monometallic catalysts. The characterization and theoretical calculation results demonstrated that the introduced suitable amount of Ni(II) could affect the structure of original Pt(II)-vinyl complexes and form a stable and unique bimetallic vinyl coordination microstructure by using a shared vinyl group, thereby affecting morphology, structure, and catalytic performance of the as-prepared bimetallic catalyst with mass ratio of Pt/Ni = 1.5:1. Changing the introduction order and introducing excessive or insufficient of Ni(II) would both disrupt the formation of this special structure and affect the catalytic performance. Additionally, the formed stable complex structure with vinyl groups could well maintain the catalytic stability. The study results exposed that the as-prepared bimetallic catalyst would possess a great industrial application potential in the hydrosilylation of alkenes by efficiently increasing the product quality and reducing operation cost.