摘要:
The invention provides a process for commercial production of syndiotactic polyolefins using a metallocene catalyst supported on silica treated with MAO. The invention includes contacting the supported metallocene catalyst with a trialkylaluminum and aging the catalyst 12 to 24 hours prior to polymerization.
摘要:
The invention provides a process for commercial production of syndiotactic polyolefins using a metallocene catalyst supported on silica treated with MAO. The invention includes contacting the supported metallocene catalyst with an aluminum alkyl and aging the catalyst prior to polymerization. In addition, the catalyst is prepolymerized in a tubular reactor prior to being introduced into the polymerization reaction zone. The treated silica is produced by removing water to a level of 0.5-1.08%, slurrying in a nonpolar solvent, adding an alumoxane, heating to reflux, cooling the slurry, and separating the solid product.
摘要:
A method of servicing a wellbore in contact with a subterranean formation, comprising placing into a wellbore a composition comprising a calcium aluminate cement and a polyvalent cation-containing compound, and allowing the composition to set. A method of increasing the thickening time of a calcium aluminate cement comprising contacting the calcium aluminate cement with a polyvalent cation-containing compound. A method of adjusting the thickening time of a calcium aluminate cement comprising contacting the calcium aluminate cement with a polyvalent cation-containing compound and at least one other set modifier.
摘要:
This invention is for a method for varying the melting points and molecular weights of syndiotactic polyolefins by using metallocene catalysts with substituents on the aryl rings of a fluorene ligand in certain positions. Electron donating substituents, for example, dialkylamino, halogen, and alkoxy groups, when present on fluorene at C1, C2, C3 or C2 and C7 render the catalyst less active and decrease the polymer molecular weight. Electron donating substituents, such as alkyl, dialkylamino, halogen or alkoxy, at C4 not only increased the catalyst efficiency but also dramatically increased the polymer molecular weight. Bulky hydrocarbyl substituents, such as alkyl, cycloalkyl and aryl groups, at C2 and C7 increase the melting point. Bulky substituents such as hydrocarbyl groups like alkyl, cycloalkyl, aryl, alkoxy and dialkylamino groups etc., at C4/C5 decrease the melting point. When multiple substituents are present on fluorene, their effects are additive.
摘要:
This invention is for a method for varying the melting points and molecular weights of syndiotactic polyolefins by using metallocene catalysts with substituents on the aryl rings of a fluorene ligand in certain positions. Electron donating substituents, for example, dialkylamino, halogen, and alkoxy groups, when present on fluorene at C1, C2, C3 or C2 and C7 render the catalyst less active and decrease the polymer molecular weight. Electron donating substituents, such as alkyl, dialkylamino, halogen or alkoxy, at C4 not only increased the catalyst efficiency but also dramatically increased the polymer molecular weight. Bulky hydrocarbyl substituents, such as alkyl, cyaloalkyl and aryl groups, at C2 and C7 increase the melting point. Bulky substituents such as hydrocarbyl groups like alkyl, cycloalkyl, aryl, alkoxy and dialkylamino groups etc., at C4/C5 decrease the melting point. When multiple substituents are present on fluorene, their effects are additive.
摘要:
A method of servicing a wellbore in contact with a subterranean formation, comprising placing into a wellbore a composition comprising a calcium aluminate cement and a polyvalent cation-containing compound, and allowing the composition to set. A method of increasing the thickening time of a calcium aluminate cement comprising contacting the calcium aluminate cement with a polyvalent cation-containing compound. A method of adjusting the thickening time of a calcium aluminate cement comprising contacting the calcium aluminate cement with a polyvalent cation-containing compound and at least one other set modifier.