| 摘要 |
The present invention provides a process for preparing a supported chromium-based catalyst for the production of polyethylene comprising the steps of a) providing a silica-based support having a specific surface area of at least 250 m 2 /g and of less than 400 m 2 /g; b) depositing a chromium compound on the support to form a chromium-based catalyst, provided that the ratio of the specific surface area of the support to chromium is at least 50000 m 2 /g Cr; c) dehydrating the product of step b) to remove physically adsorbed water by heating at a temperature of at least 250°C in an atmosphere of dry, inert gas; and d) titanating the product of step c) at a temperature of at least 250°C in an atmosphere of dry and inert gas containing at least one titanium compound of the general formula selected from R n Ti(OR') m , (RO) n Ti(OR') m and mixtures thereof, wherein R and R' are the same or different hydrocarbyl groups containing from 1 to 12 carbon atoms, and wherein n is 0 to 3, m is 1 to 4 and m+n equals 4, to form a titanated chromium-based catalyst having a ratio of specific surface area of the support to titanium content of the titanated catalyst ranging from 5000 to 20000 m 2 /g Ti. |
