Performance of CuO–ZnO–ZrO2 and CuO–ZnO–MnO as metallic functions and SAPO-18 as acid function of the catalyst for the synthesis of DME co-feeding CO2

• The addition of MnO and ZrO2 enhances the behavior of CuO–ZnO in methanol synthesis.
• SAPO-18 is active and selective for the dehydration of methanol to DME.
• The new catalysts are stable and active for the valorization of CO2 with syngas.

The kinetic behavior of the CuO–ZnO–ZrO2 (CZZr) and CuO–ZnO–MnO (CZMn) metallic functions in the methanol synthesis step has been studied under suitable operating conditions for DME synthesis, and the values of methanol yield and selectivity have been compared with those corresponding to the conventional CuO–ZnO–Al2O3 (CZA) metallic function. On the other hand, the performance (DME yield and selectivity) of SAPO-18 in the methanol dehydration step has also been compared with the conventional γ-Al2O3 acid function. Based on the kinetic behavior of the bifunctional catalysts with different mass ratios between the metallic and acid functions, a 2/1 ratio has been determined to be suitable in the single-step synthesis of DME. Moreover, the performance of the catalysts in the synthesis of DME has been compared using different reaction conditions (temperature, pressure, CO2/CO and H2/COx molar ratios in H2 + CO + CO2 feed). The results show the good behavior of the CZZr/S and CZMn/S catalysts for the valorization of CO2, since they provide higher DME yield and selectivity than a CZA/γ-Al2O3 catalyst. Although the CZZr/S catalyst has a higher CO2 sequestration capacity, the lower preparation cost of the CZMn/S catalyst means an incentive for its use.

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