Effective Suppression of CO Selectivity for CO2 Hydrogenation to High-Quality Gasoline

CO2 hydrogenation to gasoline fuels remains a sticky problem of CO selectivity from reverse water-gas shift reactions over a metal oxide and zeolite bifunctional catalyst. Herein, we report an efficient catalyst combining a Fe-Zn-Zr-T oxide hydrothermally treated with TPABr solution and HZSM-5 zeolite for CO2 hydrogenation into high-quality gasoline. The hydrothermal treatment contributes to the obvious enrichment of the Zn component and the residual Br on the surface of Fe-Zn- Zr-T oxide, as compared to Fe-Zn-Zr oxide, as well as the increased number of oxygen vacancies. These surface properties not only induce the increase of the H-2 adsorption and CO2 Low adsorption ratio but also enhance the adsorption strength of the HCOO* species and the desorption rate of CH3O* species (close intermediate of methanol) over Fe-Zn-Zr-T oxide, which are responsible for higher methanol selectivity and lower CO selectivity. Furthermore, the presence of the adsorbed CO* species and higher C-2, hydrocarbon selectivity on Fe-Zn-Zr oxide affirm the F-T route of CO2 hydrogenation except for the methanol route, while the F-T route is effectively restrained after the TPABr hydrothermal treatment of Fe-Zn-Zr-T oxide. As the Fe and Zn-Zr molar ratio decreases, more HCOO* and CH3O* species on Fe-Zn-Zr (0.1:1:1)-T-24 h can form, which is in good agreement with the much higher methanol selectivity on Fe-Zn-Zr (0.1:1:1)-T-24 h oxide and hydrocarbon selectivity on the Fe-Zn- Zr(0.1:1:1)-T-24 h@HZSM-S core-shell catalyst. The CO selectivity and C5+ isoalkane selectivity in gasoline on Fe-Zn- Zr(0.1:1:1)-T-24 h@HZSM-5 are up to 24% and 93%, respectively, with a CO2 conversion of 18%. The good matching of the Fe- Zn-Zr-T oxide and HZSM-S zeolite plays the crucial role in the C5+ isoalkanes selectivity in gasoline over the Fe-Zn-Zr-Tp HZSM-5 core-shell catalyst.

Automated summary

Efficient catalyst combining an oxide and zeolite bifunctional catalyst was developed for CO2 hydrogenation into high-quality gasoline, with enhanced surface properties and selectivity through hydrothermal treatment and specific formulation.