Investigation Of Dimethyl Ether Carbonylation Over Synthesized H-Mordenite Zeolite

Ethanol, as oxygenates and modifying agent, was important for eliminating pollutions due to vehicle emissions. DME carbonylation to MA, followed by MA hydrogenation reaction to ethanol is a new route to produce ethanol. This technological path was feasible on cost and technology, and expected to replace traditional ethanol production process in the future. The technical bottleneck of the above technological path was the low DME conversion and the expensive precious metals usage in the carbonylation reaction.The purpose of this paper were studying the effect of a various factors for the structure, morphology, physical and chemical property, and investigating the catalytic property of DME carbonylation. The factors were silica sources, SiO2/Al2O3 mole ratio, concentration, solvent and template. The study found that the H-MOR nano-sheet assemblies were synthesized with low Si O2/Al2O3 mole ratio in the absence of template, and the catalytic activity of these zeolite was more than twice higher compared with the commercial nano H-MOR zeolite because of the former's larger amount of the framework Br?nsted acidic sites. Additionally, the specific morphology of the H-MOR nano-sheet assemblies shows the excellent catalytic stability by improving mass diffusion. The coke precursor species can easily migrate from the micropores to the external surface, inhibiting hard coke blockage in zeolite frameworks.Loading the Cu ions on H-MOR zeolite can improved the DME conversion.We proposed a novel catalyst preparation method to obtain the low-loading and highly dispersed Cu in the H-MOR zeolite with high DME conversion and stability. The catalytic activity of the Cu-H-MOR-723 catalyst increased by 15 % compared with H-MOR zeolite upon DME carbonylation. More CO molecule were adsorbed in the channel, due to the existence of Cu+. The insertion of CO into the CH3* species to produce an acetyl group was the key step in the DME carbonylation. Our results show that the Cu+ in the Cu-H-MOR catalyst could adsorb more CO molecule, and thus improve the DME conversion. We inferred the synergetic mechanism between the Cu+and H-MOR zeolite upon the DME carbonylation. The DME carbonylation was initiated by the dissociative adsorption of DME on the Br?nsted acid sites of the zeolites, forming CH3* species, followed by the insertion of CO adsorbed on Cu+ into the CH3* species to produce an acetyl group. This crucial intermediate reacted withanother DME to form methyl acetate.