| 摘要 |
FIELD: polymer production. ^ SUBSTANCE: invention relates to polyolefin production technology, notably to synthesis of ethylene copolymers on modified chromium oxide catalyst under low pressure conditions is gas-phase fluidized-bed reactor. More particularly, low-pressure polyethylene production via continuous gas-phase ethylene/alpha-olefin copolymerization process is disclosed, said process being carried out in a reactor with fluidizing grate using catalyst containing chromium oxide, modifying oxide, fluorine, and silica as carrier. Reaction mixture composed of ethylene, alpha-olefin, hydrogen, and nitrogen and compositionally adjusted when being circulated by adding appropriate amounts of indicated constituents, provided that nitrogen content lies allays within a range of 30-50% based on the total volume of reaction mixture, is fed into reactor below fluidizing grate. Additional amounts of nitrogen are continuously introduced into reactor as a separate stream above fluidizing grate at the catalyst supply level. Chromium oxide contained in catalyst is chromium reduction product with chromium in the form of Cr2+ and modifying oxide is aluminum oxide prepared from alkoxyalumoxane. Silica carrier is modified with fluorine in the preliminary drying step. ^ EFFECT: increased yield of polyethylene based on unit mass of catalyst and reduced consumption of catalyst without loss in product quality. ^ 1 dg, 3 tbl, 10 ex |
