Hydrogen production by steam reforming of dimethyl ether and CO-PrOx in a metal foam micro-reactor

• Bi-functional CuZnAlCr/HZSM-5 catalysts have been used in dimethyl ether steam reforming.
• A mass ratio of 1:1 between CuZnAlCr and HZSM-5 was optimized for the process.
• The metal foam material and micro-reactor greatly enhanced the residence time of the reactant and catalyst.
• Dimethyl ether conversion of 99% and hydrogen yield of >95% was reached.
• CO concentration dropped to <10 ppm and hydrogen yield of ∼90% were achieved in the new-type system.

A bi-function catalyst containing CuZnAlCr and HZSM-5 was used to generate hydrogen by stream reforming of dimethyl ether (SRD) in a metal foam micro-reactor and a fix-bed reactor. Dimethyl ether conversion of 99% and hydrogen yield of >95% was reached with HZSM-5/CuZnAlCr (mass ratio of 1:1) in the micro-reactor. A suitable balance between the dimethyl ether hydrolysis and methanol reforming steps requires the proper acidity and the metal sites. The CuZnAlCr/HZSM-5 properties, effect of CuZnAlCr to HZSM-5 mass ratio were investigated in the metal foam micro-reactor. Moreover, CO was removed from hydrogen-rich gas by preferential oxidation reaction (CO-PrOx) with PtFe/γ-Al2O3 catalyst in a similar metal foam micro-reactor follows the SRD stage. With the optimized O2/CO ratio and reaction temperature, the CO concentration dropped to <10 ppm and hydrogen yield of ∼90% were achieved in the new-type SRD-COPrOx system. The SRD-COPrOx system provide a constant hydrogen production with CO concentration lower than 10 ppm during 20 h. The results indicate that metal foam micro-reactor has the great potential in the DME steam reforming to supply hydrogen for low-temperature fuel cells.