A comparative study of solid acids in hydrolysis and steam reforming of dimethyl ether

The catalytic performances of solid acids (Al2O3 derived from bayerite (PBT), γ-Al2O3 (ALO8), ZSM-5, H-mordenite, and TiO2) in hydrolysis of dimethyl ether (DME) to methanol have been investigated. The stronger and the larger acid sites give rise to higher conversion in hydrolysis; however, fast degradation due to coking and low quality of product are observed. The acid strength of the solid acids is as follows: H-mordenite > ZSM-5 > PBT, ALO8 > TiO2. The apparent activation energies of DME hydrolysis over H-mordenite, ZSM-5, PBT, ALO8, and TiO2 were determined as 73, 76, 101, 146, and 186 kJ mol−1, respectively. Next, steam reforming of dimethyl ether over composites of the solid acid and copper iron spinel was evaluated for hydrogen production. The composites of alumina and Cu spinel are active and durable to produce H2-rich reformate with CO2 as the major products along with trace amounts of CO. The Cu content of 13.3–17.7 wt% in the composites was optimum in terms of reforming performance. Alumina–spinel composites are superior to zeolite–spinel ones with regard to stability. Increasing the steam-to-carbon ratio obviously suppresses the catalyst degradation.

Graphical abstractThe performance of solid acids in hydrolysis of dimethyl ether (DME) strongly depends on the acid properties. The activation energies of DME hydrolysis over H-mordenite, ZSM-5, Al2O3 derived from bayerite (PBT), γ-Al2O3 (ALO8), and TiO2 were determined by Arrhenius plots. The composites of alumina and Cu spinel are superior to those of zeolite and Cu spinel with regard to stability in steam reforming of dimethyl ether.Figure optionsDownload full-size imageDownload as PowerPoint slide