Performance Study Of Hydrogen Production Through Methanol Steam Reforming In The Microreactor

In recent years, much problem about environmental pollution has been caused by the unreasonable utilization of energy. So fuel cell, as a new type of energy-conversion device, has been widely studied because of the high efficiency in the energy conversion, low energy consumption and little pollution etc. Among several types of fuel cells, the proton exchange membrane fuel cell (PEMFC) has been paied much attention to nowadays. It's well know that the proton exchange membrane fuel cell demands a fuel of hydrogen in which CO content must be very small (below about 100 mg/kg). In order to provide high-purification hydrogen for the PEMFC, many hydrogen production techniques have been investigated at home and abroad. Among of them, the technique for hydrogen production through methanol steam reforming becomes a most important choice of hydrogen production for the PEMFC. Up to now, great progress in this field has been made abroad. However, the domestic research has been still in the stage of foundation and demonstration. Thus, investigating deeply the technology for hydrogen production is the foundamental of the development of the high performance reactor used in methanol steam reforming, which will promote the technical maturity of it.The performance of methanol steam reforming in a micoreactor designed by ourselves was investigated by tightly combining engineering thermophysics with chemical engineering in the present study.Firstly, Thermodynamical equilibrium analysis was first conducted towards the reaction, which provided theoretical guide for the next experimental operation. The results showed that the reaction temperature and the steam to methanol molar ratio had an optimum value that was 1.3:1.Secondly, a two-dimensional, laminar, steady-state, mutil-component transport and reaction model was established for hydrogen production by methanol steam reforming in a microreactor, and then was verified by experiment data in the referred literature. It was proved that the numerical and analytical results were basically in agreement with the experimental data in the referred literature. And then, numerical simulation was applied to simulate the effects of the reaction conditions and the geometrical dimensions of reaction channels on the performance of reactors in the hydrogen production.The results also showed that the steam to methanol ratio had an optimum value. And a good balance should be kept between reaction temperature and inlet velocity to improve the performance of the reaction. Moreover, geometrical dimensions have great impacts on the reaction performance, too.Finally, based on the foregoing researches, experimental investigation on the performance in the hydrogen production of the microreactor was also performed on a commercial copper-based catalyst (CB-7). The effects of the water to methanol molar ratio, reaction temperature and space velocity on the performance indexes such as methanol conversion, hydrogen production rate and CO content in the products were analyzed separately and were given sound reasons for in the present study. Moreover, the results exhibited that when the space velocity was 0.955h-1,the steam to methanol ratio was 1.3:1 and reaction temperature was 260℃,the hydrogen production rate reached 0.1462mol/h corresponding to 10.2W of power output at the operating condition of 60% efficiency of fuel cell and at the 80% utilization of H2.