Abstract:
SiO
2 and La
2O
3-SiO
2 were synthesized via sol-gel method and used as support to prepared Rh-La or Rh doped catalysts by iso-volumic impregnation. Effects of doping mode of La on the catalytic performance of Rh/SiO
2 for CO hydrogenation are investigated detailedly. The results reveal that the addition of La can improve the dispersion of Rh and increase Rh
+ centers, which can effectively inhibit the formation of CO
2 and improve the selectivity of oxygenates. Furthermore, the doping mode of La can affect the interaction between La and Rh. A strong La-Rh interaction is achieved over the 2Rh-5La
2O
3/SiO
2 catalyst prepared by co-impregnation of Rh and La with SiO
2 support. The strong interaction between La and Rh can efficiently weaken the Rh-CO bonds and enhance the CO insertion reaction in the reaction process, which makes the product dominated by C
2+ oxygenates. The 2Rh/5La
2O
3-SiO
2 catalyst prepared via La
2O
3-SiO
2 composite support exhibits a weak La-Rh interaction, and methanol, ethanol and other low-carbon alcohols are obtained as the main products.