Study On Synthesis Of High Stable Acidic Hetero Atomic Mesoporous Molecular Sieve And Catalytic Pyrolysis Of Polyethylene

Polyethylene （PE） as the most widely applied in polyolefin plasticsbrings convenience to people’s lives, but it also brings serious pollutionproblem. PE currently accounts for about38%of total global polymerconsumption. China’s PE consumption is over3800MT/year, and becomesthe biggest PE consumer country in world. In2009, China’s PE productioncapacity reached8800KT, and China became the second-largest PEproduction country after the United States. It is expected that China’s PEconsumption will account for about20.6%of global consumption in2015,and our country will become the world’s largest waste plastics market andthe country of recycling. Recently the petroleum resource is increasingly dried up, so PE must be recycled in response to the national sustainabledevelopment strategy. PE’s recovery of making fuel oil by catalytic crackingnot only obtains economic benefits, but also resolves the problem ofenvironmental pollution caused by waste plastic. So it has been widelyconcerned in recent years.In this study, several modified mesoporous molecular sieves catalystswith a doped （Al, Zr, Ti） and amorphous hole wall, such as Al-MCM-41,Zr-MCM-41and Mo-MCM-41, were synthesized by hydrothermal system.MAS-7and MAS-9mesoporous molecular sieves catalysts with amorphoushole wall were synthesized by hydrothermal system and using four newacidic ionic liquids of [HSO₃-（CH₂）₃-mim][HSO₄],[HSO₃-（CH₂）₃-Nmm][HSO₄],[HSO₃-（CH₂）₃-mim][H₂PO₄],[HSO₃-（CH₂）₃-Nmm][H₂PO₄] as solvent. These catalysts were characterizedby XRD （X-ray powder diffraction）, TEM （transmission electronmicroscope）, SEM （scanning electron microscope）, N2adsorption/desorption and NH₃-TPD. The results show that the catalysts have ordered porestructure, large specific surface area and pore size, and strong acid center.In this study, for the catalytic cracking performances of L-LDPE andHDPE catalyzed by Al-SBA-15, the reaction conditions were optimized.Under the optimum conditions, the synthesized mesoporous molecular sievescatalysts were used for the catalytic cracking of L-LDPE and HDPE, and thecatalytic activities of these catalysts were studied. The results showed thatAl-SBA-15exhibited the better catalytic activity and the yield of liquids ascompared to other catalysts. The conversion and the yield of liquid productsfor L-LDPE and HDPE are90.1%and75.7%,83.5%and69.3%,respectively. In comparison with thermal cracking, the conversion and theliquid yield are very significant increased. The distribution of PE’s pyrolysisliquid products is wide and uniform, while the liquid products catalyzed byAl-SBA-15（n（Si）:n（Al）=30）are mainly light components. The number ofcarbon atoms for the products behind C10shows a gradually declining trend, and the number distribution of liquid products was concentrated between C6and C₁₄.