Catalytic Performance of Pd/Al2O3 Catalyst in the Presence of HHDMA Ligand in Acetylene Selective Hydrogenation Process

Abstract

A series of Pd-HHDMA/Al2O3 catalysts were prepared with various Pd and hexadecyl-2-hydroxyethyldimethylammonium dihydrogen phosphate (HHDMA) amounts by the reduction-deposition method. The catalysts were characterized by N2-physisorption, FE-SEM, CO-TPD, TG and FT-IR techniques. Performance tests for tail-end semi-hydrogenation of acetylene to ethylene were performed in a fixed-bed reactor at 60 °C, 10 bar and GHSV=4000 h-1 . All catalysts exhibited egg-shell Pd distribution which is beneficial for selective semihydrogenation reaction. The BET surface area and pore volume of the catalysts decreased with increasing HHDMA content for a given Pd loading. The conversion of acetylene increased with Pd loading and decreased with HHDMA content. The ethylene production increased with HHDMA whereas that of undesirable C4+ oligomerization products (“green oil”), which are coke precursors, was effectively suppressed.