1-Heptyne Selective Hydrogenation over Pd Supported Catalysts

Abstract

The catalytic behavior of Pd supported on γ-Al2O3 and on an activated pelletized carbon during the selective hydrogenation of 1-heptyne to 1-heptene under mild reaction conditions was studied. Pd/Al2O3 and Pd/C are good catalysts for this reaction, with the former showing better behavior. Under the same operating conditions, Pd/Al2O3 also presents a better performance than the classic Lindlar catalyst. The reduction and operating temperatures were found to play an important role in the catalytic behavior of the catalysts studied. The XPS results show that palladium in Pd/Al2O3 and Pd/C is electron-deficient. Within certain limits, the electron-deficient Pd species do not favor the further hydrogenation of 1-heptene to heptane, thus raising the selectivity to 1-heptene. The differences observed in the catalytic behavior of Pd/Al2O3 and Pd/C could be attributed, at least partially, to the differences in the support porosity.