Study On Methane Steam Reforming Reaction–Separation Integration For Hydrogen Production

The CO content in hydrogen must be reduced below 10 ppmv to avoid poisioning the Pt electode of proton exchange membrane fuel cell?PEMFC?.High quality hydrogen production for PEMFC can be achieved by a reaction-separation intrgration process?RSIP?of the steam methane reforming?SMR?combined with a membrane separator.Patent map analysis shows that the traditional hydrogen membrane separator prepared by Pd is difficult to commercialization widely because of its expensive price.In this paper,a much cheaper metal Ru is used for membrane separator preparation due to its good hydrogen adsorption-desorption performance and hydrogen permeation performance.Both the low temperature steam methane reforming catalysts and Ru-based membrane separators are investigated.Thermodynamic simulation of RSIP finds that H₂ in situ separation not only can break the thermodynamic equilibrium and improve methane conversion,but also make the molar ratio of CO₂/CO is about 3 to 5 times than that of without H₂ separation.RSIP can significantly improve the efficiency of hydrogen production at low temperature.By screening of the catalyst carrier,the carrier Mg_0.388Al_2.408O₄ has been synthesized by an Al₂O₃ labeled as LZ1 modified with 7.5 wt.%MgO.The catalyst with NiO loading of 10.0 wt.%shows excellent SMR activity and carbon deposition resistance performance at 500⁷00°C.The conditions of Ru plating chemically have been studied by investigation of depositing time,temperature and complexant concentration and the optimal conditions of Ru plating have been determined.The hydrogen permeation performance of the Ru-based membrane separator has been tested.The results show that Ru-based membrane separator owns good hydrogen selectively permeation performance.However,the hydrogen come from membrane separator is not meet the requirements of PEMFC.The method of low temperature CO selective methanization has been studied and used to remove a small amount of CO.A catalyst with 4a wt.%loading of active component M shows excellent CO selective methanization performance.CO concentration can be reduced to a level of less than 10 ppmv under 190°C and 0.5 MPa.