Study On Preparation And Properties Of Nanocatalysts For Hydrogen Production From Steam Reforming Of Methanol

Hydrogen is a clean, efficient energy source, however, because of its low boiling point, difficult to compress and liquefy, it is limited as the mobile energy sources. Methanol production capacity is sufficient and its energy density is high, so it is suitable as the raw material for mobile hydrogen. Compared with methanol decomposition and partial oxidation, the steam reforming of methanol (SRM) reaction has benefits of low reaction temperature, low CO and high H₂ content. Catalyst is one of the key factors to steam reforming of methanol. The CuZnAl nano-catalysts were prepared in the paper. The catalytic properties for methanol steam-reforming reaction were studied in-depth.In this paper, the thermodynamics of methanol steam reforming reaction are analysised. The reaction mechanism: methanol and water produce CO₂ and H₂, the little CO is not derived from the decomposition of methanol, but from the reverse reaction of water-gas shift; the reaction of producing CO is endothermic. The equilibrium CO content is calculated at different temperatures and the results show the CO content can be reduced theoretically.Nanostructured CuO microspheres were prepared by precipitation method using Cu(NO₃)₂ and Na₂CO₃ as raw materials. The average diameter of the CuO microspheres is 4.5μm; the surfaces of the CuO microspheres are made of pin-like nanostructures with a pin diameter of 90nm and a pin length of 600nm. The XRD analysis indicates that the nanostructured CuO microspheres are of monoclinic crystal.CuZnAl nano-catalysts are prepared by doping nanostructured CuO microspheres. The high-pressure gas chromatography-micro-reactor is used to test their catalytic properties to steam reforming of methanol. The results indicate that when its adding amount is 10%(the total moles of catalyst), the catalytic performance of the SRM is better. The reaction condition: nwater/nmethanol =1.3, SV=0.125g·h/ml, the reaction temperature is 240～260℃. Then, the content of the CO is less than 0.1%, and H₂ selectivity is about 98%, which is superior to the traditional CuZnAl catalytic performance.Combined with experimental datas, the intrinsic kinetic model of the SRM reaction is established and the parameters are estimated by using a linear least-squares method. F-test shows that the proposed kinetic model is rational.