Patent ID: 7300902

Claim:
A process for preparing a catalyst for ethylene polymerization, the catalyst comprising a magnesium halide derived from a magnesium compound represented by a formula (RM g X) p (MgX 2 ) q , in which R is an alkyl group having from 3 to 12 carbon atoms, X is halogen, and the molar ratio of q to p is between 0 and 1; wherein the solid catalyst for the ethylene polymerization is prepared by a process comprising: (1) reacting powdered magnesium with an alkyl halide of formula RX in an ether solvent to form a magnesium compound having a structure of formula (RMgX) p (MgX 2 ) q , in which R is an alkyl group having from 3 to 12 carbon atoms, X is halogen, and the molar ratio of q to p is between 0 and 1, wherein the molar ratio of the powdered magnesium to the alkyl halide is from 1:1 to 1:3; (2) impregnating the magnesium compound onto silica carrier and drying to provide a magnesium compound-loaded silica support, wherein the silica is used in such an amount that per gram silica loads from 0.5 to 5.0 mmol of magnesium element; (3) reacting the magnesium compound-loaded silica support of step (2) with an alkyl halide of formula R 1 X, in which R 1 is an alkyl group having from 3 to 12 carbon atoms and X is halogen, in an alkane solvent to give a product, wherein the molar ratio of Mg in the magnesium compound to the alkyl halide is in the range from 1:1 to 1:10; (4) reacting the product obtained from step (3) with a titanium compound and an alkyl aluminum compound to form a main catalyst component, wherein the titanium compound has a structure represented by formula Ti(OR 2 ) m Cl 4-m , R 2 is an alkyl group having from 1 to 4 carbon atoms and m is from 0 to 4, the molar ratio of the Mg in the magnesium compound to the Ti in the titanium compound is in the range from 1:0.15 to 1:2.5, and wherein the alkyl aluminum compound has a structure represented by formula R 3 n AlCl 3-n , R 3 is an alkyl group having from 1 to 14 carbon atoms and n is from 1 to 3, the molar ratio of the Mg in the magnesium compound to the Al in the alkyl aluminum compound is in the range from 1:0.08 to 1:3; and (5) contacting the main catalyst component with a cocatalyst component to form the catalyst for ethylene polymerization, wherein the cocatalyst component is an organo-aluminum compound, and the molar ratio of the Ti in the main catalyst component to the Al in the cocatalyst component is in the range from 1:30 to 1:300.