Preparation Of Hydrogen Rich Gas And Porous Graphite Carbon By Catalytic Pyrolysis Of Waste Carton

With the rapid development of the express delivery industry,the output of waste carton has increased rapidly,and it has developed into a solid pollutant that needs to be reduced and harmlessly treated.Pyrolysis is an efficient and low-polluting resource utilization method that can effectively solve the dual problems of energy and environment.The quality of direct py-rolysis products is poor,such as low gas product yield and high CO concentration,complex liquid product types,high water content,poor solid carbon pore structure and mainly amor-phous carbon.We hope to improve the performance of gases and pyrolysis carbon products through catalytic pyrolysis and catalytic reforming.Therefore,this article first studied the main pyrolysis process and product characteristics of waste carton,and then added transition metals and bimetallic catalytic pyrolysis methods to prepare hydrogen-rich gas and porous graphitic carbon,and explored the relationship between the catalyst,pyrolysis process and the physical and chemical properties of the product.Reveal the reaction mechanism of transition metal and bimetal catalyzed pyrolysis.Next,different iron-based catalysts were used to cata-lyze the reforming of volatile components to prepare hydrogen-rich gas.The effects of catalyst support and reaction temperature were explored.Based on the structural characterization of the catalyst,the cross-linking synergistic effect between the support and the active components was analyzed.A new direction for the synthesis of high-performance volatile matter reforming catalysts is proposed.First,through TG thermogravimetry and fixed-bed pyrolysis experiments（300-800℃）,the pyrolysis kinetics and product precipitation characteristics of waste carton were explored.The pyrolysis of waste carton is mainly divided into two stages.The first stage（200-500℃）is the devolatilization stage of volatile matter,and the liquid products and gas products increase significantly.The second stage（>500℃）is the carbonization stage,which is mainly based on the evolution of the carbon structure and the secondary cracking reaction of volatiles.The average activation energy calculated by KAS method is 217.24KJ/mol.At low temperatures,pyrolysis gas products are mainly CO₂.With the increase of temperature,CO,CH₄ and H₂ are gradually produced.Liquid products are mainly dehydrated sugars,acids,furans and ketones at low temperatures,and dehydrogenation and aromatization reactions occur at high tempera-tures.Polycyclic products such as naphthalene,phenanthrene and anthracene are increasing rapidly.The deoxygenation reaction of pyrolytic carbon is violent below 600℃.As the tem-perature increases,the H/C value decreases significantly,forming a large number of disordered fused ring structures.With the increase of temperature,the specific surface area of pyrolytic carbon gradually increases,reaching the maximum（87.45m²/g）at 800℃.Then,explored the influence of different transition metals（Fe,Ni,Co）,bimetals（Fe Ni,Fe Co）and bimetal ratios on the catalytic pyrolysis of waste cartons to produce hydrogen-rich gas and porous graphitic carbon.Transition metals and alloys can promote the dehydrogena-tion and deoxidation of organic compounds.Co has the best dehydrogenation effect,and Fe has the best effect on CO₂ removal.The alloy grain size is smaller than that of single metal,and its catalytic graphitization effect is better than that of single metal.Fe Co alloy has the best catalytic graphitization effect,and Ni has the worst catalytic effect;transition metals and bi-metals can greatly promote the increase of the specific surface area and pore volume of pyro-lytic carbon;the addition of iron-nickel bimetals can promote the graphitization of pyrolytic carbon The increase in the degree plays a synergistic catalytic effect.The degree of graphiti-zation is highest when the iron-nickel molar ratio is around 3:1;transition metals can promote aromatization of small molecules to form benzene ring structures and form macromolecular structures through polymerization.It is fixed in the solid product by means of vapor deposition.Finally,based on the iron-based catalyst catalytic waste carton pyrolysis volatile matter reforming hydrogen production,the interaction between different carriers and active compo-nents was explored,and the effect of catalyst type and catalytic reforming temperature on catalytic gasification was analyzed.The results show that Fe/Al₂O₃ has the strongest catalytic activity,the catalytic performance reaches the highest at 800℃.The hydrogen yield of direct catalytic reforming is as high as 7.32mmol/g,which is nearly 57.8%higher than that of waste carton direct pyrolysis.The Fe/Al₂O₃ catalyst can promote the pyrolysis of volatiles,is con-ducive to the formation of gas products,and can promote the conversion of phenols,furans and other products to generate more polycyclic products and lower the aromatization reaction temperature.The catalytic activity of different catalysts is directly affected by the type of sup-port.The interaction between the support and the active components,the mesopore volume of the support and the dispersibility of metal particles are considered to be the key factors to improve the catalytic performance.