High activity polyethylene catalysts prepared with alkoxysilane reagents
AssigneeMobil Oil Corporation
InventorsRobert I. Mink, Thomas E. Nowlin
Life of this patent
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Abstract
An ethylene copolymerization catalyst is prepared by impregnating a porous support, such as silica, with an organomagnesium compound such as a magnesium alkyl and contacting the magnesium-containing support with a silane compound which is free of hydroxyl groups, such as a tetraalkyl orthosilicate, e.g. tetraethyl orthosilicate (TEOS). A transition metal component such as titanium tetrachloride is then incorporated into the support in a specific ratio to the magnesium and silane components. Activation of this catalyst precursor with a trialkylaluminum compound results in a catalyst which is effective for the production of ethylene copolymers.
Claims17
A catalyst composition for copolymerizing ethylene and an alpha olefin of 3 to 10 carbon atoms, comprising a catalyst precursor and a trialkylaluminum cocatalyst to activate said catalyst precursor, wherein the improvement comprises a precursor comprising
- (i) silica, wherein the silica has 0.4 to 0.9 mmoles of OH groups per gram of silica;
- (ii) dibutylmagnesium, in an amount to provide a molar ratio of Mg:OH of 1.0 to 1.8
- (iii) tetraethyl orthosilicate, in an amount to provide a tetraethyl orthosilicate:Mg molar ratio of 0.50 to 0.80;
- (iv) and TICl.sub.4, in an amount to provide a molar ratio of Ti:Mg of 0.7 to 1.4 wherein the catalyst precursor has a K value, which is defined as ##EQU4## wherein is titanium metal concentration provided by TiCl.sub.4, is magnesium metal concentration provided by said dibutylmagnesium;
- is the concentration provided by said tetraethyl orthosilicate, and K is 0.23 to 0.31 wherein concentration of each of, and is in units of mmole/gram silica support;
- and wherein the precursor is prepared at a temperature in the range of 40.degree. to 65.degree. C.
A catalyst composition for copolymerizing ethylene and an alpha olefin of 3 to 10 carbon atoms, comprising a catalyst precursor and a trialkylaluminum cocatalyst to activate said catalyst precursor, wherein the precursor comprises
- (i) silica, wherein the silica has 0.4 to 0.9 mmoles of OH groups per gram of silica;
- (ii) dibutylmagnesium, in an amount to to provide a molar ratio of Mg:OH of 1.0 to 1.8
- (iii) tetraethyl orthosilicate, in an amount to provide a tetraethyl orthosilicate:Mg molar ratio of 0.50 to 0.80;
- (iv) and TiCl.sub.4, in an amount to provide a molar ratio of Ti:Mg of 0.7 to 1.4 wherein the catalyst precursor has a K value, which is defined as ##EQU5## wherein is titanium metal concentration provided by TiCl.sub.4, is magnesium metal concentration provided by said dibutylmagnesium;
- is the concentration provided by said tetraethyl orthosilicate, and K is 0.23 to 0.31;
- wherein concentration of each of, and is in units of mmole/gram silica support;
- and wherein the precursor is prepared at a temperature in the range of 40.degree. to 65.degree. C.;
- and
- wherein the cocatalyst is triethylaluminum.
A catalyst composition for copolymerizing ethylene and an alpha olefin of 3 to 10 carbon atoms, comprising a catalyst precursor and a trialkylaluminum cocatalyst to activate said catalyst precursor, wherein the precursor comprises
- (i) silica, wherein the silica has 0.4 to 0.9 mmoles of OH groups per gram of silica;
- (ii) dibutylmagnesium, in an amount to provide a molar ratio of Mg:OH of 1.0 to 1.8;
- (iii) tetraalkyl orthosilicate, in an amount to provide a tetraalkyl orthosilicate:Mg molar ratio of 0.50 to 0.80 in which the alkyl group contains 2 to 6 carbon atoms;
- (iv) and TiCl.sub.4, in an amount to provide a molar ratio of Ti:Mg of 0.7 to 1.4 wherein the catalyst precursor has a K value, which is defined as ##EQU6## wherein is titanium metal concentration provided by TiCl.sub.4, is magnesium metal concentration provided by said dibutylmagnesium;
- is the concentration provided by said tetraalkyl orthosilicate, and K is less than 0.4 wherein concentration of each of, and is in units of mmole/gram silica support;
- and wherein the precursor is prepared at a temperature in the range of 40.degree. to 65.degree. C.
A catalyst composition for copolymerizing ethylene and an alpha olefin of 3 to 10 carbon atoms, comprising a catalyst precursor and a trialkylaluminum cocatalyst to activate said catalyst precursor, wherein the precursor comprises
- (i) silica, wherein the silica has 0.4 to 0.9 mmoles of OH groups per gram of silica;
- (ii) a dialkylmagnesium compound, R.sub.m MgR'.sub.n wherein each of R and R' is an alkyl group of 4 to 10 carbon atoms, and wherein m plus n equal the valence of magnesium, wherein the dialkylmagnesium compound is present in an amount to provide a molar ratio of Mg:OH of 1.0 to 1.8,
- (iii) tetraethyl orthosilicate, in an amount to provide a tetraethyl orthosilicate:Mg molar ratio of 0.50 to 0.80;
- (iv) and TiCl.sub.4, in an amount to provide a molar ratio of Ti:Mg of 0.7 to 1.4, wherein the catalyst precursor has a K value, which is defined as ##EQU7## wherein is titanium metal concentration provided by TiCl.sub.4, is magnesium metal concentration provided by said R.sub.m MgR'.sub.n ;
- is the concentration provided by said tetraethyl orthosilicate and K is less than 0.4 wherein concentration of each of, and is in units of mmole/gram silica support;
- and wherein the precursor is prepared at a temperature in the range of 40.degree. to 65.degree. C.
A catalyst composition for copolymerizing ethylene and an alpha olefin of 3 to 10 carbon atoms, comprising a catalyst precursor and a trialkylaluminum cocatalyst to activate said catalyst precursor, wherein the precursor comprises
- (i) silica, wherein the silica has 0.4 to 0.9 mmoles of OH groups per gram of silica;
- (ii) a dialkylmagnesium compound, R.sub.m MgR'.sub.n wherein each of R and R' is an alkyl group of 4 to 10 carbon atoms, and wherein m plus n equal the valence of magnesium, wherein the dialkylmagesium compound is present in an amount to provide a molar ratio of Mg:OH of 1.0 to 1.8;
- (iii) tetraalkyl orthosilicate, in an amount to provide a tetraalkyl orthosilicate:Mg molar ratio of 0.50 to 0.80, wherein the alkyl group contains 2 to 6 carbon atoms;
- (iv) and TiCl.sub.4, in an amount to provide a molar ratio of Ti:Mg of 0.7 to 1.4, wherein the catalyst precursor has a K value, which is defined as ##EQU8## wherein is titanium metal concentration provided by TiCl4, is magnesium metal concentration provided by said dialkylmagnesium;
- is the concentration provided by said tetraalkyl orthosilicate, and K is 0.23 to 0.31 wherein concentration of each of, and is in units of mmole/gram silica support;
- and wherein the precursor is prepared at a temperature in the range of 40.degree. to 65.degree. C.
Dependencies are inferred from the claim text.