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

The traditional reaction temperatures of 1-butene isomerization to 2-butene tend to above 100   °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 CO 2 . 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.