Sustainable DME synthesis from CO2–rich syngas in a membrane assisted reactor–microchannel heat exchanger system

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

“…Detailed computational modeling studies showed that an isothermal microreactor decorated with layers of sodalite (SOD) membranes could improve DME yield from syngas (CO + CO 2 + H 2 ) by a factor of ∼20% . Membrane integration to the microheat exchangers of a modular PBR–cooler system increased syngas-to-DME yield significantly from 10 to 57% . The literature survey indicates that direct CO x (CO + CO 2 ) hydrogenation to DME is promoted by its integration with either membrane separation or heat exchange in microscaled flow paths.…”

“…Pure H 2 is dosed to the permeate channels at 2.2 × 10 –2 m s –1 for enabling cross-membrane H 2 transport to the reaction zones (Figure b). H 2 enrichment of the reactive mixture is shown to magnify the positive effect of selective steam removal on CO 2 conversion and DME formation. , Simultaneous reaction and separation are set to run isothermally at 523 K. As in the case of inlet temperatures, inlet pressures of both streams are always kept identical and set to 50 bar. A pressure gradient between the channels is not adopted to allow steady H 2 influx to the reaction mixture …”

“…These molecules should not pass across the membrane for preventing loss of the reactor performance . However, H 2 transport from the permeate zone to the reactive mixture is desired, as it increases the rates of hydrogenation reactions. , These requirements are met satisfactorily by SOD membranes that offer high steam permselectivity to methanol (233), DME (253), and CO 2 (23) and allow H 2 transport along with steam as quantified by a relatively low H 2 O/H 2 selectivity of 4.6 at 473 K. , At this temperature, the permeability of the SOD membrane is reported as 6.8 × 10 –8 mol m –2 s –1 Pa –1 . Owing to the lack of permeability data at the temperatures of the current work (503–543 K) and differences between membrane separation of multicomponent and binary mixtures, with the former being expected to be hindered by phenomena such as competitive adsorption to the membrane surface, , the permeability is taken as 3 × 10 –8 mol m –2 s –1 Pa –1 .…”

“…24 Membrane integration to the microheat exchangers of a modular PBR−cooler system increased syngas-to-DME yield significantly from 10 to 57%. 25 The literature survey indicates that direct CO x (CO + CO 2 ) hydrogenation to DME is promoted by its integration with either membrane separation or heat exchange in microscaled flow paths. DME synthesis by direct hydrogenation of CO 2 , however, is catalytically different from that of CO + CO 2 in the sense that H 2 O buildup is more significant in the former route due to combined effects of reactions 2 and 4.…”

“…The unit is also sized by numbering up the channels according to H 2 throughput of a 1 MW water electrolyzer that suits the demands of on-site applications. These aspects are neither considered in our recent studies , nor in the currently reviewed literature. In this context, the present study elucidates the capabilities of functional and volumetric intensification on catalytic upgrading of CO 2 to DME and provides in-depth insight and assistance to researchers aiming the experimental design and testing of membrane-integrated catalytic microchannel reactors for upgrading CO 2 to value-added fuels and chemicals.…”