An experimental investigation on the effects of adding a transition metal to Ni/Al2O3 for catalytic hydrogenation of CO and CO2 in presence of light alkanes and alkenes

摘要

The effect of transition metals on the activity and selectivity of a Ni/Al2O3 catalyst for carbon oxides hydrogenation was studied. It is found that each transition metal has different and distinct promoting or inhibiting influence. Nitric oxide was used as a probe molecule to study the electronic structure of a primary and two bi-metallic catalysts. Based on a series of catalyst activity and selectivity experiments, promoted bimetallic catalysts which enhanced and inhibited the activity and selectivity of the primary Ni/Al2O3 catalyst were analysed by NO-FTIR experiments. The presence of multiple sites, with different electronic properties, were observed. It is concluded that the addition of transition metals to Ni/Al2O3 markedly changed the electronic structure of the primary catalyst. Hydrogen and carbon monoxide chemisorption experiments showed that the ratio of CO/H chemisorbed species was affected by addition of Mn and Cu to Ni/Al2O3. Temperature programmed desorption of H-2 and CO confirmed the presence of different active sites on Ni/Al2O3.