Study On Direct Conversion Of Methane To Hydrogen Over Nickel-based Composite Microwave Catalyst

Energy is a necessity of daily social life and industrial development.Since fossil resources are non-renewable and the gases generated by burning them pose a serious threat to the natural environment and human health,the search for sustainable alternative fuels has become a research direction with great potential and value.As a potential zero-emission fuel and energy carrier,hydrogen has the advantages of wide sources,high combustion calorific value and non-pollution products.It is widely used in industries such as aerospace,fuel cells,electronics manufacturing and chemical raw materials,with broad development prospect.Currently,there are four major industrial applications for hydrogen production from methane:steam reforming?SRM?,carbon dioxide reforming?DMR?,partial oxidation?POM?and autothermal reforming?ATR?.The common disadvantage of this technology is that the product contains a mixture of CO_x and H₂,and it is difficult to produce high-purity hydrogen.Therefore,it is very meaningful to develop a CO_x-free hydrogen production process to replace the traditional hydrogen production method.The article proposes a new idea for the preparation of CO_x-free hydrogen,that is,applying a new type of microwave catalytic technology to the methane direct conversion hydrogen production process,so that methane can achieve efficient conversion under mild conditions,and the product can obtain pure hydrogen and carbon nanometers with good economic value material.Urea precipitation method in this paper the preparation of Ni/Mo₂C/?-Al₂O₃and Ni/Mo₂C/SBA-15 two nickel-based composite microwave catalysts were used to produce hydrogen from methane.For the Ni/Mo₂C/?-Al₂O₃and Ni/Mo₂C/SBA-15composite microwave catalysts the temperature rise performance,catalyst composition,microwave power,reaction temperature,space velocity,performance of different catalysts and microwave catalytic methane Exploring the decomposition reaction kinetics,etc.Combined with a series of characterization such as XRD,BET,SEM,TEM and RS,the experimental conclusions are as follows:?1?Use 1g 5%Ni/10%Mo₂C/g-Al₂O₃ and 8%Ni/12%Mo₂C/SBA-15 omposite catalysts respectively,using CH₄ as the reaction gas?N₂ as the balance gas?,the microwave power is 900 W,the reaction temperature is 650?,and the airspeed of the reaction is 4800 m L·g^-1·h^-1,and under normal pressure process conditions.the optimal methane conversion rate is 54.17%and 82.46%,and the hydrogen content in the product is 69.35%and 87.02%.?2?In this reasearch,the strong interaction between the catalyst carrier and the transition metal carbide Mo₂C component was fully utilized to anchor the active component Ni on the composite carrier,limit the loss of the active component,prevent the metal from accumulating and growing at high temperature,and improve the stability of the catalyst at high temperature.The experiment also show that a carrier with a large specific surface area can increase the contact interface between the reaction gas and the active component,which is beneficial to the transfer and contact of the substance.The specific surface area of the catalyst carrier SBA-15 is larger than?-Al₂O₃and has a regular mesoporous structure,so the catalytic performance of Ni/Mo₂C/SBA-15 microwave composite catalyst of hydrogen production from methane catalytic performance is Ni/Mo₂C/?-Al₂O₃ microwave composite catalyst.?3?By investigating the reaction kinetics of microwave methane conversion to hydrogen production,the apparent activation energies of Ni/Mo₂C/?-Al₂O₃and Ni/Mo₂C/SBA-15 composite microwave catalyst for methane hydrogen production activation energy of methane decomposition in the conventional heating mode,the Ni/Mo₂C/?-Al₂O₃and Ni/Mo₂C/SBA-15 catalyst systems reduce the activation energy required for methane decomposition under microwave irradiation.