Ethanol Synthesis Through Dimethyl Ether Homologization

Recently,ethanol synthesis through methanol or dimethyl ether?DME?homologization has received much attention as it has the advantage of mild reaction conditions,high selectivity and non-involvement of corrosive compounds.For the several DME homologization reaction steps,the core step is the DME carbonylation.Compared with other catalysts,mordenite zeolite is highly active for DME carbonylation reaction.So the key to the DME carbonylation reaction lies in the the synthesis of mordenite with high activity and stability.In this study,we mainly focus on the synthesis and modification of mordenite zeolites with high activity and stability.Firstly,the influence of reaction conditions to the DME carbonylation are investigated.Then,the synthesis discipline of mordenite zeolites as well as the structure-performance relationship are studied by combining results of the catalytic tests and the characterization of XRD,SEM,XRF,et al.At last,the modification effect of Cu and surfactants are investigated.According to all results above,following conclusions can be obtained:?1?DME carbonylation reaction prefers the reaction conditions of high pressure and middle temperature.High DME content in the feedstock will result in the formation of methanol.Optimized reaction conditions are as follows:feed gas DME:CO=2:98?mol:mol?,space velocity 2000 h^-1,temperature 190?C,pressure 2.0 MPa.?2?The[200]and[111]crystal planes are highly active for the DME carbonylation reaction while the quartz phase is unfavorable.The quartz phase tends to form in high SiO₂/Al₂O₃ ratio samples.Highly crystallized MOR with the preferential growth of[200]and[111]can be successfully synthesized by using TEABr as structure template and carefully adjusting the temperature,water content and basicity during the synthesis process.The quartz phase also can be restrained by controlling the pH value of mother liquor.?3?The structure of mordenite is not affected by the copper introduction while the crystallinity of in situ synthesized Cu-MOR slightly decreases.Copper introduced by in situ synthesis is more homogeneity and benefit to enhance the CO adsorption.The catalytic performance test of DME carbonylation shows that both the activity and stability are improved after the introduction of copper and the modification effect is more remarkable on Cu-MOR sample.The optimized catalytic performance of Cu-MOR catalysts could be obtained when the Cu:Al was 0.10.The specific surface area and pore volume of MOR increases after the adding some surfactants during the synthesis process.The surfactants could promote the growth of[200]crystal plane and restrain the formation of quartz phase.