Support Effects in the Hydrogenolysis of Tetrahydrofuran on Platinum Catalysts

Abstract

In the hydrogenolysis of tetrahydrofuran on supported platinum the primary product isn-butanol. On unsupported platinum the primary reaction proceeds distinctly slower than on supported platinum, and on these catalysts the activity increases in the order Pt/SiO2<Pt/Al2O3<Pt/TiO2. Thus it is deduced that for the C–O bond scission the presence of a support enhances the activity, with titania exhibiting an excellent ability to activate the C–O single bond. The primary product butanol undergoes two different secondary reactions, either by a hydrodeoxygenation to butane or by a decarbonylation to propane. The selectivity toward these products depends again on the supporting material, changing form about 0% deoxygenation by unsupported platinum to almost 100% deoxygenation by Pt/TiO2. Again, the supported catalysts are more active in C–O bond scission and therefore more selective for butane formation. The product CO causes self-poisoning of the platinum surface. As a consequence, the reaction rate decreases soon after admission of the reaction mixture. Furthermore, upon CO poisoning the selectivity is shifted toward less butane formation. This indicates that CO inhibits preferentially the sites for C–O bond scission presumably situated at the platinum support phase boundary.