Abstract: A low-bulk density solid aluminoxane has an average particle diameter of 210 to 10,000 &mgr;m and a bulk density of from 0.01 to 1.0 g/cc. Representative solid aluminoxanes may be prepared from polymethylaluminoxane or mixed alkyl group aluminoxanes. The solid aluminoxanes are useful as catalyst carriers. When used to support a metallocene, the combination may be used, for example, as catalyst for olefin polymerization Also disclosed is a prepolymerized catalyst having an average particle diameter of from 500 to 5,000 &mgr;m, useful for olefin polymerization. An olefin is pre-polymerized in the presence of a metallocene catalyst component and a solid low bulk-density aluminoxane and, optionally, an organoaluminum compound.

Abstract: A high-performance prepolymerized solid catalyst is prepared by polymerizing an olefin onto an olefin polymerization catalyst in a heterogeneous system under irradiation with an elastic wave, wherein the olefin is prepolymerized in an amount of not less than 0.1 g based on 1 mmol of a transition metal contained in the olefin polymerization catalyst. The elastic wave is preferably an ultrasonic wave. In a process for heterogeneous polymerization of an olefin, an olefin is subjected to slurry polymerization or gas phase polymerization in the presence of the prepolymerized solid catalyst. In a process for heterogeneous polymerization of an olefin, an olefin may be polymerized onto the olefin polymerization catalyst in a heterogeneous system under irradiation with an elastic wave to prepare polyolefin. Therefore, the heterogeneous polymerization of an olefin can be stably conducted and polyolefins of uniform property and high quality can be obtained.

Abstract: A high-performance prepolymerized solid catalyst is prepared by polymerizing an olefin onto an olefin polymerization catalyst in a heterogeneous system under irradiation with an elastic wave, wherein the olefin is prepolymerized in an amount of not less than 0.1 g based on 1 mmol of a transition metal contained in the olefin polymerization catalyst. The elastic wave is preferably an ultrasonic wave.

Abstract: A process for the preparation of polyolefin which comprises polymerizing or copolymerizing olefin in the presence of a catalyst for olefin polymerization comprising (A) a metallocene compound of a transition metal selected from the Group IVB of the periodic table, and (B) an organoaluminum oxy-compound; wherein the organoaluminum oxy-compound (B) is added to the polymerization system in the form of a slurry in an aliphatic hydrocarbon or alicyclic hydrocarbon, and the polymerization is carried out in the presence of the aliphatic hydrocarbon diluent or an alicyclic hydrocarbon diluent having a boiling point below 100.degree. C.