Application of spherical clay mesoporous composite materials in polyethylene metallocene catalysts
Kilograms of spherical clay mesoporous composites ( sepiolite,diatomite and attapulgite) were synthesized by centrifugal spray dryer. X-ray diffraction structure analysis,specific surface area-pore size distribution,and TEM testing were conducted to verify mesoporous structure and highly ordered pores in the composites. SEM analysis results show that these three new materials have uniform sphericity and good dispersibility. The influence of atomizer rotation speed and reactant ratio on the particle shape of spherical clay mesoporous composites was also studied, and the best spray drying conditions were obtained. The composition,structure, and microscopic morphology of clay mesoporous composite polyethylene catalysts were investigated in the article. The test results indicate that the three types of clay mesoporous composite materials still maintain good microstructure and unique mesoporous material pore structure after loading polyethylene catalyst. The optimum conditions for the composites were entrance/exit temperature of 200 ℃/100℃,content of clay slurry of 30％,and atomizer rotation speed of 12000 r·min-1. Three new materials were used as carriers to load polyethylene catalysts for high-pressure ethylene polymerization in small-scale experiments. The results showed that the activity of the three catalysts for ethylene polymeriza-tion[(4000-4300) gPE·(gcat·h) -1]was better than that of the current industrial carrier 955 silica gel loaded with the same metallocene for ethylene polymerization[(1005 gPE·(gcat·h) -1). The im-portant physical properties of polyethylene powder, including bulk density, melt index, average particle size D50,and crushing rate,are superior to those obtained from industrial 955 silica gel.
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维普
