The Study Of Waste Polyethylene Catalytic Cracking At Common Temperature-ive Development And Economic Cooperation In Mid-China's Rising

At present,most waste plastics are treated by burning,firing or heating degradation.Some plastics are recycled for utilization.Unfortunately,the result is not satisfied.After the research on the development of degradable plastics and some research on degradation of plastics,the study on the catalytic pyrolysis of the ordinary plastics becomes the leading topic.Particularly,the catalytic pyrolysis of polyethylene becomes the principal problem,which will be favor of the resolution of the white pollution ultimately.The processes for producing fuel oils were systematically studied by catalytic cracking from polyethylene.Pyrolysis of polyethylene is usually carried on above 400℃.In order to reduce the reaction temperature,polar origanic solvent was employed.Its good solubility to plastic may enhance the contact efficiency between solid catalyst and plastic,which effectively reduces the reaction temperature under 200℃.The performance of catalysts made in different conditions has been studied.The catalysts were made by co-precipitation method.The catalysts were characterized using XRD,Laser Granularity Analyzer,IR,and FT-Raman.The results show that ZrO₂ catalysts have activity in this reaction.Zr²⁺content and temperature are related to activity of catalysts.With the content of 0.05mol/L of Zr²⁺and temperature of 400℃,the prepared catalyst shows the highest activity,the yield is 46.73%.In the experiment we put in polar organic solvent in order to decrease the reaction temperature. Types of cracking catalysts were evaluated in the paper,to find out the optimal cracking catalyst.The effects of various factors such as catalyst preparation condition, solvent,the dosage of catalyst,etc on catalytic cracking processes were investigated.Based on the study on the ZrO₂ solid acid catalyst,we carried on photo-catalyst degeneration of polyethylene with the SiO₂-TiO₂ catalyst.The result indicated that without UV(40W intensity)irradiation,SiO₂-TiO₂ catalyst has activity in this reaction.But in the same condition,under UV(40W intensity)irradiation,the breaking of PE chains will be more quickly than without the irradiation,and the yield is 25.76%.SiO₂-TiO₂ photo-catalyst was prepared by the sol-gel method,and was used to catalyze the degradation of PE under UV(40W intensity)irradiation for 12h.The properties of the catalyst and the degraded PE were characterized by Laser Granularity Analyzer,XRD,UV-Vis diffuse reflection spectra and FT-Raman.The study belongs in the project of environmental protection,so its benefit is obvious in the environment,the society and the economy.