Conversion of n-pentane and of n-butane catalyzed by platinum-containing WOx/TiO2

Tungstated titania, with and without platinum, was used to catalyze the con version of n-butane and of n-pentane at atmospheric pressure and temperatur es in the range of 423-573 K, both in the presence and in the absence of H- 2 in the feed stream to a flow reactor. The catalysts were active for isome rization and cracking, and the products included alkenes, in contrast to th ose observed in catalysis by tungstated zirconia. The catalytic activity of tungstated titania is much less than that of sulfated zirconia and similar to that of tungstated zirconia. The results characterizing tungstated tita nia indicate a bifunctional reaction network involving metal and acidic sit es responsible for hydrogenation/dehydrogenation and carbenium ion reaction s, respectively. Platinum in the catalyst and H-2 in the feed strongly supp ress the otherwise rapid catalyst deactivation associated with coke deposit ion. The catalyst was found to be stable after a period of initial deactiva tion, and kinetics data are reported for partially deactivated catalysts. H igh platinum contents lead to high selectivities for cracking in the presen ce of H-2 and high selectivities for unsaturated products in the absence of H-2. Increasing tungsten loadings raise catalyst acidity and favor isomeri zation. The performance of tungstated titania containing platinum resembles that of the zirconia-based catalysts less than it resembles the performanc e of platinum supported on (chlorided) alumina, a well-known naphtha reform ing catalyst.