An Efficient Microcapsule Catalyst for One-Step Ethanol Synthesis from Dimethyl Ether and Syngas

This paper presents a tailor-made microcapsule catalyst that integrates a metal oxide (Cu/ZnO) catalyst as core and modified zeolite (Cu-MOR) as shell, into one multifunctional composite catalyst (CZ@Cu-MOR) for one-step ethanol synthesis strategy. The modified zeolite shells were instrumental in separating original syngas from the metal cores, spontaneously kicking off the key DME carbonylation reaction step, while restraining the hostile CO hydrogenation reaction over the core catalyst. The proposed synthesis mechanism of the microcapsule catalyst hugely creates surface area owing to catalyst size, and a uniquely compact interface between the two active centers where they work synergistically to accelerate parallel reactions involving MA formation and its subsequent conversion to EtOH. The addition of a porogen, such as CTAB, to the as-synthesized microcapsule catalyst, enhanced zeolite shell porosity without leaching metal active components, and stepped up access of reactants to catalytic sites, reaching a remarkable 26.4% conversion of DME and 45.8% selectivity of EtOH. The higher metal (promoter) dispersion provided by the zeolite shells, suppressed coking and enhanced stability, with unchanging activity for 50 h time on stream. Furthermore, the CZ@Cu-MOR microcapsule catalyst could be easily regenerated. Therefore, micro-encapsulation using the linker-seeds-shell approach demonstrates a promising research strategy in developing alternative energy sources from heterogeneous catalytic processes.