Designing a novel dual bed reactor to realize efficient ethanol synthesis from dimethyl ether and syngas

A novel dual bed reactor packed with a combination of a zeolite (H-modernite or H-ferrierite) catalyst and a CuZnAl catalyst was proposed to realize direct ethanol (EtOH) synthesis from dimethyl ether (DME) and syngas (CO + H-2). DME and CO were firstly introduced into the upper zeolite bed to commence the carbonylation reaction, and then H-2 was directly introduced into the CuZnAl catalyst bed below to accomplish the hydrogenation of methyl acetate (MA) produced at the first catalyst bed. In this novel dual bed process, DME and CO were introduced into the reactor at the top of the first catalyst bed layer, but H-2 was introduced into the second catalyst bed layer directly through an inner stainless steel tube equipped with evenly distributed holes. Benefitting from the precise control of the distribution of the reactants on the surface of different catalysts, an enhanced catalytic performance was obtained compared with the conventional dual bed reactor which introduced DME and syngas into the reactor simultaneously. The synergistic effects offered by this novel dual bed reactor were further confirmed by numerous comparative tests. Our results show that the excellent catalytic performance in this novel dual bed reactor was ascribed to the improved CO partial pressure in the upper zeolite catalyst bed. Compared with the conventional dual bed reactor, both DME conversion and EtOH yield were almost doubled in this novel dual bed reactor packed with the combination of the H-ferrierite and CuZnAl catalysts.