Reduced sheeting during alpha-olefin! polymerisation. - in low-pressure fluidised-bed reactor, by introducing temp.-controlled nitrogen contg. small amts. of water

摘要

A method of reducing sheeting during polymsn. of alpha-olefins (I) is a low pressure fluidised bed reactor utilising titanium or vanadium based cpds. as catalysts together with alkyl aluminium cocatalysts, comprises: introducing water into the reactor in a sufficient amt. to maintain the electrostatic levels at the site of possible sheeting without substantially altering the effectiveness of the catalysts. Specifically, the water is introduced into the reactor by passing a pressurised inert gas, esp. nitrogen, at a controlled rate of flow through a temp. controlled container contg. water, directing the gas contg. added water into a mixt. contg. ethylene, and subsequently introducing the water/ethylene mixt. into the reactor. The flow rates of nitrogen and ethylene, and the water temp. are controlled and determined responsive to static levels in the reactor. The water content is 0.1-2 ppm by vol. w.r.t. ethylene. The flow rate of nitrogen is varied between 0-11 lbs/hr. for an ethylene feed of 0-50,000 lbs/hr. The temp. of the water in the container is 10-40 deg.C.