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Direct DME synthesis via CO 2 hydrogenation in a membrane-integrated microchannel reactor is modeled. The proposed reactor comprises rectangular permeate and reaction channels separated by layers of sodalite membranes, permitting only H 2 O and H 2 transport. Reaction channels, dosed with CO 2 and H 2 , are washcoated with a physical mixture of methanol synthesis (Cu-ZnO/Al 2 O 3 (CZA)) and dehydration (HZSM-5) catalysts. Pure H 2 -fed permeate channels host the steam transported from reaction channels. The mathematical model of the isothermal, steady-state reactor involves conservation equations in catalyst and fluid phases, catalytic reactions, and membrane separation. The model is successfully benchmarked against literature-based experimental data. Differences between isothermal and non-isothermal models remain negligible. At 543 K, 50 bar, and H 2 /CO 2 = 3, cross-membrane H 2 O and H 2 transport increases membraneless CO 2 conversion and DME yield values by more than 2-fold, i.e., up to ∼73 and ∼35%, respectively. Counter-current flow configuration offers more H 2 O separation than the co-current one. The sweep-to-reactive stream inlet velocity ratio affects cross-membrane mass transfer significantly. Reactor performance is positively correlated with the CZA/HZSM-5 mass ratio. A ∼7 m 3 -sized reactor can transform ∼1 × 10 3 tons/year of CO 2 into 2.76 × 10 2 tons/year of DME.

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