Isoprene gas phase hydrogenation catalyzed by ThNi2 and UNi2

Abstract

The study of isoprene (2-methyl-1,3-butadiene) gas phase hydrogenation on ThNi2 and UNi2 was undertaken and the effect of the 5f element on nickel catalytic behavior investigated. At nearly steady state, the reaction products were isopentane and isopentenes (2-methyl-2-butene, 2-methyl-1-butene and 3-methyl-1-butene). The total selectivity to isopentenes was higher on ThNi2 (∼80 mol%) than on UNi2 (∼50 mol%) but, in both cases lower than that on pure Ni (∼96 mol%). The sum of 2-methyl-2-butene + 2-methyl-1-butene selectivities (valuable products for the tert-amyl methyl ether process) was ∼75 mol% on ThNi2, whereas on UNi2 it was significantly lower (∼50 mol%). ThNi2 and UNi2 total selectivity to isopentenes is nearly time invariant. The difference of catalytic properties between ThNi2 and UNi2 can be explained by electronic transfer from the 5f element to Ni that generates an electronic density supply on nickel, which is higher on ThNi2.