GB1191168A - Production of Polyethylene - Google Patents

Abstract

1,191,168. Polymerizing ethylene. HALCON INTERNATIONAL Inc. 29 Sept., 1967 [6 Oct., 1966; 25 Nov., 1966], No. 44501/67. Heading C3P. Polyethylene is produced by a process which comprises feeding a mixture of ethylene and initiator to an elongated reactor, passing the mixture through a preheat zone wherein the mixture is indirectly heated to 120‹ to 160‹ C., passing the preheated mixture through a first reaction zone wherein the preheated mixture is indirectly heated to a peak temperature exceeding 275‹ C. and most of the ethylene is converted to polyethylene, the temperature profile of the first reaction zone embracing temperatures in the range 120‹ to 320‹ C., passing the resultant mixture from the first reaction zone to a first cooling zone wherein the resultant mixture is indirectly cooled to a temperature not exceeding 275‹ C., adding initiator to the cooled mixture, passing the cooled mixture with added initiator to a second reaction zone wherein the cooled mixture with added initiator is indirectly heated to a peak temperature exceeding 275‹ C. and additional ethylene is converted to polyethylene, the temperature profile of the second reaction zone embracing temperatures in the range 180‹ to 320‹ C., passing the resulting mixture from the second reaction zone to a second cooling zone wherein the resultant mixture from the second reaction zone is indirectly cooled to a temperature not exceeding 275‹ C., and separating the resulting polyethylene from unreacted ethylene. The process may comprise additional steps of passing cooled mixture with added initiator to further reaction zones with indirect heating and having temperature profiles embracing temperatures in the range 180‹ to 320‹ C. The separated ethylene may be recycled to the preheat zone. In examples, (3) ethylene, together with (4) propane as chain transfer agent, is polymerized with oxygen in the first zone and t.-butyl peroxide in the second.