Basic Research On Double-plate Coal Direct Chemical Looping Hydrogen Generation Of Cu-Fe Oxygen Carrier

The main problem of coal direct chemical looping hydrogen generation?CLHG?is that coal ash and oxygen carrier cannot be effectively separated,which makes coal ash and oxygen carrier?OC?active components adhere,and OC activity is reduced or even inactivated after multiple cycles.Therefore,the ash separation is the key to clean and efficient hydrogen production by direct chemical looping of coal.In this paper,the impact factor of the reactor and OC chemical characteristic on the CLHG was studied.Cu-Fe composite oxygen carrier was prepared by chemical synthesis method.The effect of the separation method on the reaction characteristics of coal direct CLHG was discussed in a double plate reactor.X-ray diffraction?XRD?was used to analyze the phase structure of OC before and after the reaction;SEM-EDS was used to analyze the surface morphology of OC before and after the reaction;BET was used to analyze the specific surface area of oxygen carrier.The results show that the double plate reactor has some advantages in separation of coal ash.Within the range of experimental conditions,the higher the copper oxide content,the smaller the coal particle size and the greater the water gas flow rate,the better the effect of hydrogen yield.The implantation of potassium accelerates the gasification process of coal with large particle size,but the excessive happen to the early hydrogen generation stage and carbon deposition at the end of reduction,in which 1% K has a better hydrogen production.The higher the reaction temperature is,the weaker the carbon deposition is.When the purity of CO₂ and H₂ O need not to be high,900? has a better experimental effect to reduce the external energy consumption.The oxygen consumed in reduction of OC is preferentially from Cu O,while Fe/Fe O preferentially oxidizes Cu/Cu₂ O with H₂ O in the hydrogen production stage.With the increase of the number of cycles,the oxygen storage performance of Cu Fe₂O₄ decreases,and the mechanical performance of Cu Fe₂O₄ decreases.Reductive Cu₂ O and Fe O dispersion are the main reasons of hydrogen production.Carbon deposition in hydrogen production stage has a great influence on hydrogen purity.Compared with Cu Fe₂O₄ the implantation of Mg Al₂O₃ plays an important role in stabilizing the redox ability and mechanical properties of the active components.With the increase of the number of cycles,the performance of the system is slightly reduced but not much.After the reduction reaction,the inert carrier can be partially decomposed into Mg O or alumina,in which Mg O can increase the oxygen content of OC.The composition of oxygen carrier after air oxidation is almost the same as that of fresh oxygen carrier,and the addition of inert carrier can not avoid the slight sintering of OC and the reduction of specific surface area.Air oxidation plays a positive role in the recovery of specific surface area and pore channel of oxygen carrier.The pore volume of oxygen carrier in oxidation stage is even higher than that in reduction stage...