丁二醇活化氯化镁制备Ziegler-Natta 催化剂及其乙烯聚合

采用1,4-丁二醇作为沉淀剂，析出溶解于四氢呋喃(THF)中的MgCl2，制备得到具有新型结构的MgCl2/THF/HO(CH2)4OH化合物.该化合物经过三乙基铝(TEA)处理得到MgCl2·nTHF·mAl(OR)3载体，负载TiCl4后得到了高活性的Ti-Mg催化剂.采用X 射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、感应耦合等离子体发射光谱(ICP)、核磁共振(NMR)和氮气吸附法等手段对其结构进行表征，发现所制得的载体呈现δ-MgCl2晶型，催化剂具有较大的比表面积和较高的钛质量分数（5.79%）.乙烯聚合结果表明，催化剂活性较高，每克Ti单位时间单位反应压力下可制得聚乙烯47.38 kg，即47.38 kg·g-1·h-1·10-5Pa-1，且具有缓慢衰减型动力学曲线.聚合产物具有较宽的分子量分布（MWD= 9.02）.加氢后产物的分子量分布变窄（MWD= 6.81），但随氢气体积分数的增加变化不大.

Preparation of Ziegler-Natta catalyst by butanediol activation and its ethylene polymerization

MgCl2/THF/HO(CH2)4OH adduct with a novel structure was synthesized by using 1,4-butanediol to precipitate MgCl2 from tetrahydrofuran solution. The resulting adduct was treated by triethylaluminum(TEA) and activated MgCl2·nTHF·mAl(OR)3 support was obtained. Highly active catalyst for ethylene polymerization was prepared by impregnating TiCl4 on this support. The synthesized support and catalyst was characterized by XRD, FT-IR, ICP, NMR and nitrogen adsorption method. The characterization results demonstrated that the support was in the crystal form of δ-MgCl2, and the catalyst showed high surface area and titanium mass fraction(5.79%). The ethylene polymerization results indicated the catalyst had high catalytic activity. 47.38 kg polyethylene (PE)·could be produced by one gram of Titanium under unit time and unit pressure, namely, 47.38 kg·g-1·h-1·10-5Pa-1. A slow declined kinetic curve of the catalyst was observed in polymerization. Moreover, the molecular weight distribution (MWD) of polyethylene produced by this catalyst was broad (MWD= 9.02). The MWD was narrowed in the presence of hydrogen, and changed slightly with increasing hydrogen volume fraction.