A γ-alumina obtained as 1/16 inch extrudates from Criterion Catalyst Company L.P., Michigan City, Ind. was used. First, an ammonium heptamolybdate solution was prepared by dissolving (NH4)6 Mo7O24 ·4H2O in concentrated H3PO4 and water so that the ammonium molybdate concentration was 9.855 weight %, the H3PO4 concentration was 12.681 weight %, and water made up the rest. Then, 10 g of the alumina was impregnated at 25 ° C. with 5.32 g of the ammonium heptamolybdate solution to form a mixture. The mixture was then calcined in air at 538° C. for 6 hours to produce 10.18 g of a molybdenum oxide- and phosphorus oxide-impregnated alumina containing 2.807 weight % molybdenum and 2.096 weight % phosphorus (control catalyst).
