在Phillips催化剂基础上开发出CrO_x-VO_x/SiO₂双中心催化剂，并用（NH₄）₂SO₄对其进行改性，考察了（NH₄）₂SO₄的浸渍方式、浸渍量和催化剂焙烧温度对乙烯聚合行为和产物结构与性能的影响。结果表明，（NH₄）₂SO₄改性的铬钒双金属催化剂的乙烯聚合活性得到提高，且随（NH₄）₂SO₄负载量的增加，活性呈现先增加后降低的趋势。采用共浸渍制备的催化剂的乙烯聚合活性大于分布浸渍法。（NH₄）₂SO₄对V活性组分有促进作用，使改性催化剂的均聚产物分子质量增加，加入1-己烯共聚单体后，分子质量进一步增加。

A CrO_x-VO_x/SiO₂ bimetallic catalyst is developed on the basis of Phillips catalyst and modified with (NH₄)₂SO₄.The influences of calcination temperature for catalyst,and impregnation method and amount of (NH₄)₂SO₄ on polymerization behavior of ethylene and properties of product are investigated.The results show that the addition of (NH₄)₂SO₄ helps CrO_x-VO_x/SiO₂ bimetallic catalyst improve activity in ethylene polymerization.With the increase of (NH₄)₂SO₄ dosage,the activity of the catalyst increases first and decreases then.The activity of the catalyst prepared by co-impregnation method is greater than that made by distribution impregnation method.(NH₄)₂SO₄ can promote V active site and hence increases the molecular weight of homopolymer produced.The addition of 1-hexene can further increase the molecular weight of homopolymer.

郑云江(1994-),男,硕士研究生,研究方向为聚乙烯催化剂制备与聚合反应研究,zyjeat@163.com