Solution-state NMR study of organic components of industrial Ziegler-Natta catalysts: Effect of by-products on catalyst performance
Solution-state NMR study of organic components of industrial Ziegler-Natta catalysts: Effect of by-products on catalyst performance
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DOI：
10.1016/j.apcata.2020.117971
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发表时间：
2021-01-09
影响因子：
5.5
通讯作者：
Taniike, Toshiaki
中科院分区：
文献类型：
--
作者：
Thakur, Ashutosh;Chammingkwan, Patchanee;Taniike, Toshiaki
制备Ziegler-Natta(ZN)催化剂的化学路线伴随着副产物的形成，这些副产物以不同的量留在最终的催化剂中。在ZN催化剂的历史上，对催化剂中存在的这些副产物的分析很少。在本论文中，我们制备了不同类型的镁(OEt)(2)基氮化锌催化剂，并用溶液核磁共振方法对催化剂的有机成分进行了表征和定量。研究发现，根据内给电子体的分子结构和催化剂的制备条件，内给电子体可以发生副反应生成有机副产物。所有催化剂都含有不同量的钛烷氧基副产物，这些副产物是在Mg(OEt)(2)与TiCl4反应中形成的，不利于催化剂的活性。这些副产物增加了聚丙烯中无定形部分的数量，降低了高度结晶部分的立构规整度。讨论了解释烷氧基钛副产物负面影响的可能假设。
Chemical routes for preparing Ziegler-Natta (ZN) catalysts accompany the formation of by-products that remain in final catalysts in different amounts. In the history of ZN catalysts, much less emphasis has been given to analyze such by-products present in catalysts. Herein, we prepared various Mg(OEt)(2)-based ZN catalysts and conducted solution-state NMR measurements to characterize and quantify the organic components of these catalysts. It was found that, depending on the molecular structure of the internal donor (ID) and catalyst preparation conditions, an ID can undergo side reactions to produce organic by-products. All the catalysts contained different amounts of titanium alkoxy by-products formed in the reaction between Mg(OEt)(2) and TiCl4, which were detrimental for the catalyst activity. These by-products were responsible for increasing the amount of the amorphous fraction in polypropylene and decreasing the highly crystalline fraction's stereoregularity. Possible hypotheses to explain the negative impacts of titanium alkoxy by-products are discussed.