Industrial & Engineering Chemistry Research, Vol.59, No.26, 11962-11969, 2020
Direct Synthesis of C-5-C-13 iso-Paraffins from Carbon Dioxide over Hybrid Catalyst in a Near-Critical n-Hexane Fluid
Direct CO2 hydrogenation to hydrocarbons via methanol synthesis is carried out over hybrid catalysts composed of Cu-ZnO and various zeolites by introducing a near-critical n-hexane fluid into the reactor. A high CO2 conversion of 46.7% and a C-5 -C-9 hydrocarbons selectivity of 48.3% are observed over the hybrid catalyst composed of Cu-ZnO and ZSM-5 (SiO2/Al2O3 = 23) when an n-hexane fluid at a partial pressure of 1.5 MPa is employed. The selectivity for C-5 -C-9 hydrocarbons can be further increased by loading a Pd promoter on the ZSM-5(23) zeolite. CO and dimethyl ether (DME) are predominantly produced at a low CO2 conversion of 28.8% while without using the n-hexane fluid. In addition, C-8 -C-13 iso-paraffins (jet fuel fractions) are significantly produced with a selectivity of 51.7% in the presence of the n-hexane fluid, when USY zeolite is used in the hybrid catalyst.