Effect of combining metallic and acid functions in CZA/HZSM-5 desilicated zeolite catalysts on the DME steam reforming in a fluidized bed

• Bifunctional catalysts have been used in the dimethyl ether steam reforming.
• Balance should be struck between acidity and number and dispersion of metal sites.
• The method for contacting the phases and their mass ratio are crucial aspects.
• A high H2 yield is obtained with the catalyst prepared by wet physical mixing.
• A mass ratio of 1:1 between metallic and acid functions is suitable for the process.

A study has been carried out on the effect of combining the metallic (CuO–ZnO–Al2O3) and acid (HZSM-5 zeolite treated with NaOH) functions, and of their mass ratio, on the kinetic performance in the steam reforming of dimethyl ether (SRD). The runs have been conducted in a fluidized bed reactor in the 225–325 °C range, and the reaction indices (dimethyl ether and methanol conversions, and H2 and CO yields) have been explained based on the physico-chemical properties of the catalyst.A suitable synergism between dimethyl ether hydrolysis and methanol reforming steps requires striking a balance between acidity and the number and dispersion of metal sites, as happens in the catalyst prepared by wet physical mixing with a mass ratio of 1:1 between the metallic function and the acid one. This catalyst allows obtaining high values of dimethyl ether conversion and H2 yield in the 275–300 °C range by minimizing the CO formation rate and deactivation by coke.

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