Solid component for preparing olefin polymerization catalyst, and preparation method therefor and application thereof

A carrier of polyolefin catalysts, comprising:

• (i) a magnesium compound represented by the following formula (1):
• wherein R1 is a C1 to C12 linear or branched alkyl;
• R2 and R3, which are the same or different, are hydrogen or an unsubstituted or halogenated C1 to C5 linear or branched alkyl;
• X is a halogen;
• m is 0.1 to 1.9;
• n is 0.1 to 1.9;
• and m+n=2;
• (ii) a Lewis base (LB), and
• (iii) optionally, a metal component other than magnesium, preferably the other metal component is one or both of iron and cupper;
• preferably the content of the other metal component in terms of metal in the solid component is from 0 to 1 wt %,
• wherein the Lewis base is a compound represented by general formula (II),
• wherein, R5 and R7, which are the same or different, are hydrogen or an unsubstituted or hydroxyl-substituted C1 to C8 linear or branched alkyl;
• R6 is a C1 to C8 linear or branched alkylene;
• or
• the Lewis base is an amide compound represented by general formula (II′),
• wherein, R10 is hydrogen, amino or a C1 to C8 linear or branched alkyl, and R11 and R12, which are the same or different, are hydrogen or a C1 to C8 linear or branched alkyl.