Study On Preparation And Characteristics Of Fe-based Oxygen Carriers In Chemical Looping Reforming Of Glycerol For Hydrogen Production

With the increasing depletion of fossil energy and the enhancement of human awareness of low carbon and environmental protection,the development of alternative biomass energy sources has become crucial.Due to the continuous development of biodiesel industry,how to deal with glycerol as the main by-product in the biodiesel production process has become one of the important issues for scholars from all countries,among which the use of chemical looping to produce hydrogen is an effective way.The Fe-based oxygen carrier has good carbon resistance,low toxicity and high activity,and is widely used in chemical looping reforming for hydrogen production.In order to improve the activity and stability of the Fe based oxygen carrier,this study brings in the transition metal into the oxygen carrying for modification to explore the influence of Ni doping content and doped metal（Cu/Co）on the hydrogen performance of the oxygen carrying system,so as to provide a basis for the construction of efficient oxygen carrying body in the chemical chain reforming hydrogen production system.The main research contents of this paper are described as follows:1.In view of the poor performance of pure Fe₂O₃in chemical looping reforming hydrogen production,Ni O-Fe₂O₃/Al₂O₃was developed by dip-precipitation method,which is easy to be reduced by fuel and reoxidized by air.In order to accurately grasp the influence of the experimental parameters temperature（T）,water to carbon ratio（S/C）,and load（M）on H₂content（HL）and H₂selectivity（S）,the study established the quadratic orthogonal model based on the quadratic regression.Using XRD,XPS,SEM/EDX,TEM,and H₂-TPR.Using mathematical model calculation,combined with experimental exploration,to make the results more reliable.It is found that under the best conditions of T=600°C,S/C=1.0 mol/mol and M=0,the best hydrogen selectivity and hydrogen content in this experiment are 85.33%and 78.41%,respectively.At T=700°C,S/C=1.0 mol/mol,M=2.5%,with the most stable fluctuation range of hydrogen content in this experiment,within 4%.2.In order to explore the hydrogen production performance of perovskite Fe-based oxygen carrier in glycerol chemical chain reforming,La Ni_1-xFe_xO_3-λoxygen carrier was developed by using sol gel method,with the mass percentage of 0,5%,10%,15%,20%,25%and 30%metal Ni doping.In the doping ratio experiment of Ni,the H₂selectivity of La Ni_0.1Fe_0.9O_3-λis 91%,and the La Ni_0.1Fe_0.9O_3-λcan reach the highest among 5 groups in terms of glycerol conversion and H₂yield,producing the same effect as La Ni_0.3Fe_0.7O_3-λ,while doping less Ni metal,which is more economical.After exploring the influence of temperature on the hydrogen production performance of La Ni_0.1Fe_0.9O_3-λ,it is found that the temperature increase can improve the conversion rate and yield of glycerol,but the temperature is too high will cause the sintering phenomenon of oxygen carrier,leading to the decrease of the conversion rate of raw material and hydrogen production performance.In the10 cycle stability of La Ni_0.1Fe_0.9O_3-λoxygen carrier,the H₂content was basically unchanged at about 60%,and the H₂selectivity was maintained at90%.3.Based on the optimal doping ratio of LaNi_1-xFe_xO_3-λoxygen carrier,the perovskite La M_0.1Fe_0.9O_3-λ（M=Co,Cu）oxygen carrier was developed using sol gel method,with B doping of La Fe O_3-λoxygen carrier using metal Cu and Co,respectively,to investigate the influence of metal species on titanium Fe base oxygen carrier in steam hydrogen reforming experiment of glycerol chemical chain,and compare the performance with La Ni_0.1Fe_0.9O_3-λoxygen carrier.La Ni_0.1Fe_0.9O_3-λH₂content is 7.28%higher than La Fe O_3-λoxygen content;H₂selectivity is 15%higher than doped metal Cu(S_H2=75.07%).Compared with La Fe O_3-λoxygen body,the glycerol conversion rate of La Co_0.1Fe_0.9O_3-λoxygen body increased by 16.5%and the H₂yield increased by10%.However,the H₂selectivity and H₂content of La Co_0.1Fe_0.9O_3-λwere8.21%and 3.84%lower than La Ni_0.1Fe_0.9O_3-λ,respectively,so comprehensively,the use of Ni modification had better effects.In 10 performance cycle stability analysis,La Ni_0.1Fe_0.9O_3-λH₂selectivity stabilized at 90%and CO selectivity fluctuated in the range of 62%-84%.In contrast,LaNi_0.1Fe_0.9O_3-λhas a higher reactivity.