H 2-reduced Pt/MoO 3 as a selective catalyst for heptane isomerization

Abstract

H 2 reduction of Pt/MoO 3 was accompanied by an increase in the surface area. H 2-reduced Pt/MoO 3 exhibited the largest surface area of 250 m 2/g at reduction degrees of 60–70%. The surface area was enlarged only when Pt/MoO 3 was reduced after heating in a stream of H 2. The catalytic activity of H 2-reduced Pt/MoO 3 for heptane isomerization was also dependent on the extent of reduction. The highest isomerization activity appeared at a reduction degree of about 70%. Heptane was selectively isomerized on H 2-reduced Pt/MoO 3 with reduction degrees below 80%, and the high selectivity was preserved even at high conversion levels. The catalytic behaviors of H 2-reduced Pt/MoO 3 were strongly affected by heating atmosphere. Reduction after heating in H 2 provided a much more active and selective catalyst for heptane isomerization than reduction after heating in N 2. We suggest from the results of XRD measurements that reduction of Pt/MoO 3 through the formation of a H x MoO 3 phase can be an important step to enlarge the surface area and to generate the active sites for heptane isomerization.