| In this study, several mesoporous molecular sieves, containing Al, Zr, Mo, were synthesized by hydrothermal system and some strong acidic groups like BO33-, SO42-and ZrO2,were incorporated into the frame of the mesoporous molecular sieves to obtain the strong acidic mesoporous molecular sieves catalysts. The obtained materials were firstly used as catalysts in pyrolysis of polyolefins. The synthesized Mesoporous molecular sieves were characterized by XRD, FT-IR, BET, ESR and NH3-TPD. The results show that the obtained materials are of the characteristics of mesoporous molecular sieves, better long-range order and crystallinity, and that super acidic groups have been combined with the frame of mesoporous molecular sieve so that the acidity of MCM-41 was improved. The catalytic cracking performance of different strong acidic mesoporous molecular sieves catalysts was compared by model reactions of catalytic pyrolysis of HDPE, LDPE and PP. According to the characterization of these catalysts, the relationship between pore structure, acidities and catalytic activities of different strong acidic mesoporous molecular sieves was studied. The results indicate that the strength of acid has more significant effect on catalytic pyrolysis of HDPE and LDPE. However the catalytic activity of mesoporous molecular sieves can be controlled by the pore structures of catalysts in catalytic pyrolysis of PP.The catalysts that were of best catalytic activities were used in catalytic pyrolysis of polyolefins. Influences of reaction conditions such as Si/M(M=Al, Zr, Mo) ratio, reaction time, temperature and dosage of catalyst on the pyrolysis were examined and the optimum conditions were obtained. The optimum conditions of catalytic pyrolysis of LDPE over Al-MCM-41 (Si/Al=40) were reaction temperature 420℃, catalyst/LDPE(mass ratio)=0. 02 and reaction time 70min.Under the optimum conditions, the conversion of LDPE was 97.1% and the yield of liquid products was 83. 6%.
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