The effects of surface hydroxyl groups and SiO2 content of alumina supports for FeK/Al2O3 catalysts on their activity and product selectivity for CO2 hydrogenation to hydrocarbons reaction were investigated. A series of iron-based catalysts supported on six commercial Al2O3 supports were prepared and tested for hydrocarbons production in a fixed-bed reactor. Surface acidic-basic hydroxyls distribution of the supports were evaluated by Fourier transform infrared (FT-IR) and point of zero charge (PZC) measurement. It was found that the PZC of Al2O3 supports strongly affects the dispersion as well as particle size of the Fe-based catalysts. Increasing PZC value of Al2O3, the iron dispersion increased and particle size decreased. The highest CO2 conversion (54.4%) and C5+ hydrocarbons selectivity (31.1%) were achieved when the PZC was 8.0. CO2 conversion and the long-chain products selectivity decreased when PZC declined. Moreover, SiO2-doping of alumina strongly affected the surface acidic-basic hydroxyls distribution of the supports, while a desired SiO2 content improved the catalyst activity by adjusting CO adsorption and the reduction behavior of the iron-based catalysts.
All Science Journal Classification (ASJC) codes
- General Chemistry
- General Chemical Engineering
- Industrial and Manufacturing Engineering