Method for synthesizing carbon hydrocarbon compound through CO2 hydrogenation

The invention relates to a method for synthesizing a carbon hydrocarbon compound through CO2 hydrogenation. A catalyst is adopted, the catalyst is a K-M co-promoted Fe-based catalyst and is composed of carbon black, Fe2O3NGr, transition metal M and alkali metal K, and Fe2O3NGr is nitrogen-doped graphene half-coated Fe2O3 particles. In the K-M co-promoted Fe-based catalyst, the content of the Fe element is 1-40 wt%, the content of the transition metal M is 1-30 wt%, and the content of the alkali metal K is 1-5 wt%. The transition metal M is one or more of palladium, nickel, cobalt, indium and chromium. The alkali metal K is alkali metal potassium. After the CO2 hydrogenation reaction is finished, the conversion rate of CO2 is 22.73 to 40.62 percent, the selectivity of CH4 is 15.26 to 37.12 percent, the selectivity of CO is 13.05 to 89.96 percent, the selectivity of carbon hydrocarbon with the carbon atom number of 2 to 4 is 12.22 to 43.99 percent, and the selectivity of carbon hydrocarbon with the carbon atom