Patent ID: 6927260

Claim:
A process for preparing polyethylene from “feed ethylene”, which comprises: a) a hydrogenation stage in which “feed ethylene” containing impurities or secondary components such as acetylene and ethane is reacted with hydrogen to remove the acetylene by catalytic hydrogenation to form ethylene and part of the ethylene is converted into ethane, and b) a polymerization stage in which the ethylene leaving stage a) is reacted in the gas phase in a fluidized-bed reactor to form polyethylene, where the fluidizing gas used comprises, on entering the reactor, ethene and from 20 to 70% by volume of ethane, based on the total volume of the fluidizing gas, possibly together with further components, where the concentration specified in b) in addition to the ethane already present in the “feed ethylene” results from a targeted conversion of ethylene in a) into ethane and optionally/or a feed-stream of ethane added to the “feed ethylene”, and wherein the fluidized gas leaving the reactor in stage b) is cooled and recycled directly back to the reactor.