Preparation Of Anode Catalyst For Sulfur Dioxide Depolarization By Biomass-Based N/O Doubledoped Materials

In recent years,the growth of global demand for energy has resulted in excessive consumption of fossil energy and serious environmental pollution.Therefore,it is extremely urgent to develop and utilize green and clean renewable energy systems.Hydrogen energy is considered as the cleanest and most effective energy carrier because of its abundant resources,renewable and pollution-free.The mixed sulfur cycle is the most promising technology for long-term,large-scale hydrogen production.SO₂depolarization electrolysis（SDE）is the key of mixed sulfur process.Most of the low efficiency of electrolytic cell is caused by anode reaction kinetics,so the research on anode catalyst is of great significance.At present,the research focuses on two aspects:one is to reduce the amount of precious metal supported on the catalyst for cost saving,and the other is to develop new carriers to improve the catalyst life and avoid rapid degradation.Biomass carbon materials are new materials widely used in the field of electrochemistry.Compared with traditional carriers such as carbon black,biomass carbon has larger specific surface area and richer pore structure.In this paper,the preparation of platinum-based bimetallic catalysts and the development of new biomass-based carbon materials for SDE reaction were studied to improve the activity,stability and life of anode catalysts.（1）The catalysts Pt-M/C were prepared using Pt as the primary metal,Pd,Cr and Cu as the secondary metal,respectively.Electrochemical tests were carried out on the three catalysts,among which Pt-Cr/C showed excellent electrochemical activity and stability.Subsequent tests were carried out by changing the metal load of Pt-Cr/C.The results indicate that in the range of 10wt%～60 wt%,the electrochemical performance of 60 wt%Pt-Cr/C was better than that of commercial Pt/C.（2）First lignin,holocellulose and cellulose were extracted from corn straw,after the four kinds of biomass as a source of carbon,with Ca Cl₂as activator,through chemical activation method,the material base of carbon materials preparation was born,The effects of different biomass on the structure and properties of carbon materials were analyzed.The holocellulose based porous carbon showed good performance,with a specific surface area of 519.81 m²/g,the pore capacity is0.65 cm³/g,and the current density can reach 780 m A/cm²at 1.2V voltage.（3）A series of biomass-based N/O double-doped carbon materials were successfully prepared by using corn stalk as raw material,calcium chloride chemical activation method,changing the proportion of activator addition,carbonization time and carbonization temperature in carbonization conditions,and Pt-Cr/BPC bimetal catalysts were respectively prepared by using them as support.Through electrochemical testing of the catalyst,the optimum preparation condition was obtained as the mass ratio of biomass to calcium chloride 1:0.6,carbonization temperature 750℃,carbonization time 1.5 h,and the measured current density of Pt-Cr/BPC-6-750-1.5 at 1.2 V voltage reached980 m A/cm²,close to the commercial Pt/C 1080 m A/cm².（4）Carbon materials were prepared using urea and melamine as nitrogen sources and corn straw as carbon sources,which were different from nitrogen and oxygen doped by biomass itself.The effects of these two doping methods on the SDE reaction were analyzed.The results showed that Pt-Cr/BPC-6-750-1.5 without nitrogen source had better electrocatalytic effect.The second is Pt-Cr/BPC-CON₂H₄.