Room-temperature isomerization of 1-butene to 2-butene over palladium-loaded silica nanospheres catalyst

摘要

The traditional reaction temperatures of 1-butene isomerization to 2-butene tend to above 100 degrees C, while here we report the unique catalytic performance of a Pd loaded silica nanospheres catalyst for 1-butene double-bond-shift isomerization at room temperature and showed 2-butene yield of 37.0%. Furthermore, the introduction of O-2 into the reaction mixture dramatically improved the yield efficiency to 57.2% without the formation of by-product CO2. The reaction process is proved that the ratio of trans-2-butene to cis-2-butene in the final product was determined by the trans:cis ratio of the butenylcarbenium ion intermediate, and the ratio of trans-2-butene to cis-2-butene decreased with the increasing reaction temperature. Unlike other palladium catalyst systems, Pd-0 nanoparticles were proved to act as catalytic active sites, and their oxidation and aggregation resulted in a decrease in activity. Most importantly, the catalyst acidity affected the catalytic performance, which provides theoretical basis for the choice of catalysts. (C) 2016 Elsevier B.V. All rights reserved.