Adsorption Performance Of CO₂ On Nitrogenous Biomass Materials

As we all know,carbon dioxide（CO₂）emissions from the burning of fossil fuels exacerbate the greenhouse effect.The intensified greenhouse effect has caused a series of environmental problems such as global warming,sea level rise,ocean acidification and climate change.Therefore,CO₂ emission reduction is an inevitable trend for future environmental improvement.CO₂ reduction technologies include source control,process control and end control.Among them,the most widely used is terminal control.CO₂ terminal control technology methods mainly include adsorption method,absorption method,and membrane separation method.The adsorption method has the advantages of low operating cost,low energy consumption,relatively mild operating conditions,and stable performance.It is an important technical direction to solve the problem of CO₂ emissions in the future.Among them,the development and preparation of low-cost,stable performance and good adsorption performance of the adsorbent is the key to the development of practical adsorption process.Therefore,this thesis takes advantage of the availability of biomass raw materials,low cost and many other advantages,and develops nitrogen-containing biomass porous carbon CO₂ adsorption materials,aiming to improve the material’s CO₂ adsorption selectivity.The thesis focuses on the CO₂ adsorption selectivity of the material,and optimizes the preparation of nitrogen-containing biomass porous adsorption materials by changing the processing conditions and calcination conditions;the surface morphology,pore structure,surface element and group distribution of nitrogen-containing biomass CO₂ adsorption materials were explored using SEM,BET,FTIR and other test and characterization techniques.The experiment explored the influence of preparation conditions on the adsorption performance of CO₂adsorption materials,and analyzed the adsorption thermodynamic process by using adsorption isotherms at different temperatures to obtain the temperature effect and pressure effect during static adsorption.Through the use of adsorption heat,adsorption potential,adsorption potential analysis and calculation to study the interaction between CO₂ and nitrogen-containing biomass porous carbon materials,the CO₂ adsorption capacity of nitrogen-containing biomass porous carbon materials is obtained.The research results show that KOH activation of coconut shell can significantly increase the CO₂ adsorption capacity of porous carbon materials;the addition of urea helps to increase the nitrogen content in porous carbon materials and improve selectivity;lean oxygen conditions are more suitable than anaerobic conditions to improve the CO₂ adsorption performance of materials.After increasing the calcination temperature and increasing the calcination time,the pore volume of the material increases and the amount of CO₂ adsorption increases,but at the same time the sample loss will also increase.The adsorption of CO₂ by nitrogen-containing biomass materials is a spontaneous process of entropy reduction and exotherm based on physical adsorption;in the process,the temperature effect is stronger under higher adsorption pressure,and under lower adsorption pressure,the adsorption capacity is more sensitive to pressure;the interaction between CO₂ and nitrogen-containing biomass porous carbon materials increases with the increase of adsorption pressure,and decreases with the increase of adsorption temperature,it shows that the work done by the material on CO₂causes the order of some CO₂ to increase and its surface energy decreases.