Acid activation of montmorillonite and its application for production of hydrogen via steam reforming of dimethyl ether

A series of acid-activated montmorillonites (Acid-MMTs) were prepared via Na-montmorillonite treated with nitric acid solution at different treatment temperature and time. And the Acid-MMTs used as solid acid were physically mixed with commercial Cu/ZnO/Al₂O₃ to obtain bifunctional catalysts for steam reforming of dimethyl ether (SRD) reaction. The results showed that the structure, texture and acidity of Acid-MMTs were significantly changed compared with Na-MMT, which was dependent on the acid treatment conditions. The structure and acidity of Acid-MMTs obviously affected the SRD performance over bifunctional catalyst. The bifunctional catalyst composed of the Na-MMT activated in 20% nitric acid solution at 80 ℃ for 12 h (Acid-MMT-80/12) and Cu/ZnO/Al₂O₃ exhibited the best SRD performance, with the dimethyl ether conversion and H₂ yield reaching 97% and 94% under the conditions of p =0.1 MPa, t =350 ℃, GHSV=3000 h⁻¹, respectively, and DME conversion and H₂ yield remained basically constant in 10 h, indicating that the catalyst had better stability.