Bimetallic Pt-Co Catalysts for the Liquid-Phase WGS

Bimetallic Pt-Co catalysts derived from cobalt aluminate spinel were investigated in the liquid-phase water-gas shift (WGS) reaction and CO hydrogenation. Liquid-phase WGS is a key reaction in the aqueous-phase reforming (APR) of polyols; thus, WGS activity is essential to formulate good APR catalysts. In this work, catalysts with different Pt/Co molar ratios were synthesized together with a reference Pt/alumina. All the synthesized catalysts were characterized by various techniques in order to gain knowledge on their structural and surface characteristics. WGS activity was tested with a feedstream of CO/H2O = 1/15 (space-time of 76.8 kg(cat)center dot s/mol(CO)), isothermal operation at 260 degrees C and 50 bar, for 10 TOS. Bimetallic Pt-Co catalysts showed improved activity in liquid-phase WGS in comparison to bare Co or Pt catalysts, which was ascribed to the synergistic effect. Despite being subjected to an increased hydrogen concentration in the feedstream (H-2/CO between 0 and 12/3), these catalysts maintained a preferential selectivity towards WGS activity. In addition, the effect of temperature (220-260 degrees C) and pressure (25-50 bar) was investigated over a catalyst with 0.3Pt/CoAl. CO conversion and CO(2)yield were more sensitive to temperature, while a higher pressure favored methane production. The measured activation energy in the 220-260 degrees C temperature range was 51.5 kJ/mol.