用乙酰氯淬灭法测定Ziegler-Natta催化剂的活性中心数

DETERMINATION OF THE NUMBER OF ACTIVE CENTERS ON ZIEGLER-NATTA CATALYSTS BY QUENCHING WITH ACETYL CHLORIDE

在测定Zieler-Natta催化剂活性中心数的主要方法中,动力学-分子量法不能测定聚合中任意时刻的活性中心数,氚醇淬灭法、阻聚法及^(14)CO标记法等的可靠性尚未得到充分肯定,因而有必要寻找兼具可靠、方便及适用面广等特点的新测定方法。本文报道用乙酰氯作为一种新的淬灭剂测定TiCl_3-烷基铝催化1-辛烯聚合体系活性中心数的初步结果。

The reactions of Solvay TiCl3-AlR3 (R=C2H5,i-C4H9) catalysts with acetyl chloride were studied. The main reaction, which is much faster than the reactions between A1R3 and CH3COC1, is as follows:It is found that when CH3COC1 was introduced into 1-octene polymerization systems catalyzed by TiCl3-AlR3 for 5-15min, it reacted selectively and completely with the active centers to produce acetyl-ended polymer chains.With CH3COC1 as a quenching agent, the number of active centers in .these polymerization systems were determined by measuring the content of carbonyl in the polymer, and the results consist with those obtained by kinetics-molecular-weight method.