Study On Methane Steam Reforming Reaction And Separation In Palladium Membrane Reactor

Hydrogen is recognized as a clean energy source in the world.It owns the highest energy density per unit mass,and its combustion products are water and environmentally benign.It' s major application is used as a proton exchange membrane fuel cell fuel.The integrated methane steam reforming with membrane separation for high purity hydrogen production is one of the hotspots of hydrogen energy researchAt a proper temperature range,hydrogen can permeate from the high pressure side of the Pd membrane to the low pressure side to produce pure hydrogen by Pd membrane separation.The Pd membrane can be combined with natural gas steam reforming to produce hydrogen,in which the hydrogen is continuously removed from the reaction side through the palladium membrane,the thermodynamic equilibrium of the reaction has been broken,in such way,the higher CH4 conversion and the higher yield of hydrogen can be obtained at a lower temperatureIn this paper,two kinds of thermodynamic methods are used to calculate hydrogen production by steam reforming with membrane separation process.The effects of temperature,pressure,steam to carbon ratio and different hydrogen separation ratios on CH4 conversion and hydrogen content in the product dry gas are obtained.Furthermore,for a typical dry gas composition of natural gas steam reforming,the feed gas with different CO2 and CO contents was used for Pd membrane separation under different temperature,pressure and flow rate.The results show that the flow rate and temperature have little effect on the Pd membrane separation of hydrogen.The pressure and COx content have strong effect on the Pd membrane separation of hydrogen.High pressure and low COx are beneficial to the separation of hydrogen.High pressure and high COx are beneficial to reverse water gas shift reaction and methanation reactionOn the basis of the above,the methane steam reforming and Pd membrane separation were integrated to carry out the integrated reaction-separation hydrogen production.The results show that temperature and pressure have a significant effect on the reaction-separation integrated hydrogen production.Hydrogen separation and recovery can be enhanced by increasing pressure.Meanwhile,CH4 conversion also has been increased with pressure,this is totally opposite of thermodynamics equalibrium Increasing the steam to carbon ratio can significantly increase the CH4 conversion,but the yield of hydrogen is significantly reduced.