Study On Methane Catalytic Reforming To Generate Hydrogen In Membrane Reactor

The world-wide energy crisis and environmental pollution are become increasinglyserious, which raise a higher demand for energy diversity and clean energy. Hydrogen,which is highly efficient, non-polluting and sustainable, perceived as an ideal energy inthe future, and also the best fuel for fuel cells, attracts people’s much attention. Methaneautothermal reforming is a process which uses CH₄, H₂O and O2to produce for syngas.And the reaction system can occur spontaneously coupling with self-heating. Due to thethermodynamic equilibrium limited, it’s difficult for methane to realize completelyconversion, and result in wasting raw materials and polluting environment, and the fuelcells demand pure hydrogen, these are all related to the purification of hydrogen. Thispaper, aiming to the problems of low conversion ratio of methane and the impuritycontained in the generated hydrogen, propose a membrane reactor to realizecontinuously remove hydrogen from the reactor, in order to promote the chemicalequilibrium.Thermodynamic equilibrium constant method and experiments were used in thispaper, methane autothermal reforming in traditional reactor and membrane reactor werestudied, and the effects of temperature, air to methane mole ratio, steam to methanemole ratio, pressure, flow rate and purge flow rate were researched.Results show that: Increasing temperature can obviously improve the methaneconversion ratio, and hydrogen yield increases firstly and then slightly decreases withincreasing the temperature in traditional reactor. With increasing temperature, thehydrogen yield of permeation side gradually increase firstly, and slightly decreaseswhen temperature higher then900K, the hydrogen yield of reaction side graduallydecreases and then keeps stable. H₂/CO mole ratio is drastically reduces with increasingtemperature for all the two reactors. The use of membrane reactor can reduce thereaction temperature. Methane autothermal reforming shows its best performance at800℃in traditional reactor and at750℃in membrane reactor.The increase of air to methane mole ratio and steam to methane mole ratiopromotes methane conversion ratio, but excessive oxygen content reduces hydrogen andCO yield, and the increase of steam to methane mole ratio improves H₂/O mole ratio, soH₂/CO mole ratio can be regulated by changing the steam to methane mole ratio.Methane autothermal reforming shows its best performance at air to methane mole ratio equals to1and steam to methane mole ratio equals to2.Methane conversion ratio increases with increasing the flow rate. For membranereactor, permeating pressure does an inhibition on methane conversion ratio, butreacting pressure does little effect on methane autothermal reforming. Hydrogen can bepromptly removed from the reactor as increasing purge flow rate, which promote thepermeability, thus improve hydrogen permeation ratio, so as the methane conversionratio and productions yield and H₂/CO mole ratio.