Syngas Conversion To Light Aromatics And Liquid Fuel:Selectivity Regulation On Bifunctional Catalysts

At present,with the depletion of petroleum and the growing demand of energy,it is necessary to explore new ways for efficiently converting non-petroleum carbon resources.The conversion of syngas is one of the feasible steps in the utilization of non-petroleum-based carbon resources.Starting from syngas,it can produce liquid fuels such as gasoline and diesel,and raw material of chemical industry such as olefins and aromatics.However,the conventional way of synthesis gas conversion follows F'ischer-Tropsch synthesis route with complicated product spectrum,limited by the distribution of Anderson-Schulz-Flory(ASF).It is difficult to obtain high selectivity to target products.In this thesis,following the idea of bifunctional catalysts,we present M-ZrO2/H-ZSM-5 for directly converting syngas to light aromatics,and FeM-K/H-ZSM-5 for directly converting syngas to C5+liquid fuel.We further investigated the catalytic mechanisms and the correlation between structure and catalytic performance.For M-ZrO2/H-ZSM-55 the syngas to methanol reaction of the oxide catalyst was combined with the methanol-to-aromatic reaction of H-ZSM-5 to form a catalyst for the one-step conversion of the synthesis gas to the aromatic hydrocarbon.Over 70%selectivity of aromatics and 20%CO conversion was achieved under 430 ? and 3 MPa,with considerable stability.We performed surface modification to this catalyst with TEOS to improve the selectivity to BTX.By performing characterization of the modified zeolites,we found that the structure and the total zamounts of strong acid was not affectecd,but the external BrOnsted acid sites decreased significantly.Different methanol synthesis catalysts can also infl uence the distribution of aromatic products.For FeM-K/H-ZSM-5,the Fischer-Tropsch synthesis to olefins of Fe-based catalyst with the olefirn polymerization of acidic zeolites was combined to form a catalyst for C5+ liquid fuel production.We investigated the effects of different promoters on the conversion of syngas on Fe catalysts and the effects of different zeolites on C5+selectivity.The results showed that Cu can promote the reduction of Fe and reduce the selectivity of C5+on Fe catalyst.K can promote the carbonization of Fe,suppress the hydrogenation ability of catalyst,increase the formation of olefins and decrease the selectivity of methane.Compared with H-MCM-22,H-Beta,and other zeolites,H-ZSM-5 has the highest selectivity to C5+.