Experimental Study On Dimethyl Ether Reforming System For Hydrogen Production

Energy is an essential material basis for human survival, and is also the driving force of social economy forward. Rapid economic development has brought a double crisis including environmental pollution and energy shortage. Therefore, the use of hydrogen for fuel cell vehicle has had an extensive interest. However, hydrogen fuel faces the challenges of storage and delivery. Therefore, one of the strategies is to develop the technology for hydrogen production from liquid fuels. Dimethyl ether has recently been presented to be a promising reforming feedstock for on-site hydrogen production, due to its high energy density, non-toxic, ease of transport and similar physical properties to LPG. DME steam reforming technology not only extends the DME application as fuel, but also benefits to environmental protection.In our previous wok, a catalyst with high catalytic activity of steam reforming, that is Cu-Ni/γ-Al2O3, was developed. And reforming system was simulated. In this paper, the effects of preparation methods and operating conditions on catalyst performances were investigated. Then, a hydrogen production system including DME steam reforming, water-gas shift reaction(WGS) and pressure swing adsorption (PSA) purifying process had been set up and tested. The main results are as follows:(1) Cu-Ni/γ-Al2O3 catalysts were prepared respectively by the deposition precipitation (DP) method and isovolumetric impregnation (IM) method. The effect of the different preparation methods on catalyst performance was investigated. The results showed that DP method was superior to IM method for the the better activity and stability. The effect of the different calcination temperature on catalyst structure and performance was also investigated. The catalyst calcined at 500℃had moderate BET surface area, pore volume and average pore diameter. As calcination temperature rising, the content of spinel copper increased, and the particle diameter of metal copper also increased from 12.6 nm to 33.2 nm.(2) Hydrogen production from DME steam reforming was investigated in a fixed-bed continuous-flow stainless steel reactor. The results showed that the suitable process conditions were reduction temperature of 400℃, reaction temperature of 350℃, under 0.1 MPa, a space velocity of 3240 mL·(gcat·h)-1, diameter ratio of particle to reactor of 1/13-1/26.(3) A hydrogen production system including DME steam reforming, WGS reaction and PSA purifying process was set up and tested. Hydrogen-rich gas was produced from dimethyl ether steam reforming on Cu-Ni/γ-Al2O3, in which the CO content was reduced to 8% by WGS using commercial B113 High (middle) temperature shift catalyst. Then through PSA, the CO content was reduced to 4 ppm. By 130 h testing, results showed that the system performance was stable, and hydrogen yield of system was 700 mL/min.