Numerical Analysis of CO₂-to-DME Conversion in a Membrane Microchannel Reactor

Abstract

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.

CO2 to dimethyl ether (DME): structural and functional insights of hybrid catalysts

“…193,194 Koybasi et al modeled a membrane microchannel reactor with rectangular permeate and catalyst-coated (wash-coated Cu-ZnO/Al 2 O 3 + H-ZSM-5) reaction channels separated by a sodalite membrane layer that allows H 2 O and H 2 transport. 195 Introduction of the membrane results in a 2-fold increase in CO 2 conversion and DME yield. Considering a pilot-scale electrolysis unit of H 2 ∼18 kg h −1 capacity, they have also calculated that an eight microchannel reactor block with about 7 m 3 volume can convert ∼1 × 10 3 tons of CO 2 into ∼2.76 × 10 2 tons of DME per year.…”

Prospect of Direct Dimethyl Ether Production from CO2: Reactor Design Development

“…is an environmentally friendly, non-toxic oxygenate with intriguing properties that has a variety of applications. It is considered as a clean transportation fuel because of its high cetane number (55)(56)(57)(58)(59)(60), low boiling point (−25 °C), low ignition temperature and good composition of oxygen content (35 wt. %), which facilitate faster vaporisation and better combustion quality [4].…”

CFD Simulation of Methanol Dehydration Step through an Adiabatic Fixed-bed Reactor of DME Synthesis

“…Natural gas is the best choice among the above reactors due to its cheapness and availability. Production of DME from natural gas allows the investor to mass produce independently of fluctuations in world oil prices [13]. Due to its chemical nature, LPG is an octane fuel, and DME is a cetane fuel.…”