Catalyst for producing aliphatic polycarbonate and the preparation thereof

This invention relates to a catalyst for producing aliphatic polycarbonate, which is composed of a rare-earth coordination compound; an alkyl metal compound; a polyol; and a carbonate. The catalytic efficiency of the catalyst of the present invention is more than 8×104g polymer/mol RE(RE is rare earth metal). The number average molecular weight of the polymer is higher than 30, 000. The degree of carbon dioxide fixation is more than 42 wt % and the content of alternative sequence structure exceeds 97%.