Solid MAO composition containing Al

1. A solid polymethylaluminoxane composition comprising polymethylaluminoxane, trimethylaluminum and Al 2 O 3 , wherein

(i) the aluminum content is in the range of 36 mass % to 43 mass %, and

(ii) the Al 2 O 3 content is in the range of 0.001 mol % to 10 mol % based on aluminum.

2. The solid polymethylaluminoxane composition according to claim 1 , wherein at least part of the Al 2 O 3 exists in the solid polymethylaluminoxane composition in the form of crystal grains.

3. The solid polymethylaluminoxane composition according to claim 2 , wherein the crystal grains of the Al 2 O 3 are in the range of 0.1 to 200 nm in size.

4. The solid polymethylaluminoxane composition according to claim 1 , wherein at least part of the Al 2 O 3 exists in amorphous form in the solid polymethylaluminoxane composition.

5. The solid polymethylaluminoxane composition according to claim 1 , wherein the polymethylaluminoxane contains the unit denoted by general formula (I) below:

-[(Me)AlO] n —  (I)

wherein, Me represents a methyl group and n denotes an integer from 10 to 50.

6. The solid polymethylaluminoxane composition according to claim 1 , wherein Me(TMAL), the mole fraction of methyl groups derived from the trimethylaluminum, is equal to or less than 15 mol %.

7. The solid polymethylaluminoxane composition according to claim 1 , which is particulate and has a volume-based median diameter of 1 to 50 μm.

8. The solid polymethylaluminoxane composition according to claim 1 , which contains no solid carrier, provided that the Al 2 O 3 is excluded from the solid carrier.

9. The solid polymethylaluminoxane composition according to claim 1 , which is solid state at least at temperatures of 30° C. or less.

10. A method for manufacturing a solid polymethylaluminoxane composition comprising Al 2 O 3 , the method comprising:

a step (a) of heating an aromatic hydrocarbon solution containing trimethylaluminum and the polymethylaluminoxane containing the unit denoted by general formula (II) below (referred to hereinafter as the solution of polymethylaluminoxane composition) to cause solid polymethylaluminoxane composition containing trimethylaluminum and polymethylaluminoxane to precipitate; and

a step (b) of heating a solution containing the solid polymethylaluminoxane composition precipitated in step (a) above at the same temperature or at a different temperature from that in step (a) to thereby precipitate Al 2 O 3 in the solid polymethylaluminoxane composition:

-[(Me)AlO] n —  (II)

wherein, n is an integer from 10 to 50.

11. The manufacturing method according to claim 10 , wherein a dry inert gas is bubbled through the solution polymethylaluminoxane composition prior to the step (a), and/or a dry inert gas is bubbled through the solution polymethylaluminoxane composition during at least part of the step (a).

12. An olefin polymerization catalyst comprising the solid polymethylaluminoxane composition according to claim 1 and a catalyst component in the form of the transition metal compounds denoted by general formula (IV) below:

MR 5 R 6 R 7 R 8   (IV)

wherein M denotes a transition metal element, and one or two of the R 5 through R 8 organic groups denote a cycloalkanedienyl skeleton, and the remainder of the R 5 through R 8 organic groups independently denote a hydrocarbon group with 1 to 20 carbon atoms, an alkoxy group, an aryloxy group, an alkylsilyl group, an amino group, an imino group, a hydrogen atom, or a halogen atom; and each organic group comprising a cycloalkanedienyl skeleton may have an alkyl group, an alkoxy group, an aryloxy group, an alkylsilyl group, an alkylamide group, an alkylimide group, an alkylamino group, an alkylimino group, or a halogen atom.

13. A method for manufacturing a polyolefin, comprising polymerizing an olefin in the presence of the catalyst according to claim 12 .