Nifant'ev Ilya E, Tavtorkin Alexander N, Vinogradov Alexey A, Korchagina Sofia A, Chinova Maria S, Borisov Roman S, Artem'ev Grigory A, Ivchenko Pavel V
A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia.
Chemistry Department, M.V. Lomonosov Moscow State University, 1-3 Leninskie Gory, 119991 Moscow, Russia.
Polymers (Basel). 2021 Nov 14;13(22):3930. doi: 10.3390/polym13223930.
Ultra-high molecular weight poly-α-olefins are widely used as drag reducing agents (DRAs) for pipeline transportation of oil and refined petroleum products. The synthesis of polyolefin DRAs is based on low-temperature Ziegler-Natta (ZN) polymerization of higher α-olefins. 1-Hexene based DRAs, the most effective at room temperature, typically lose DR activity at low temperatures. The use of 1-hexene copolymers with C8-C12 linear α-olefins appears to offer a solution to the problem of low-temperature drag reducing. The present work aims to develop two-stage synthesis of polyolefin DRAs that is based on selective oligomerization of ethylene in the presence of efficient chromium/aminodiphosphine catalysts (Cr-PNP), followed by polymerization of the olefin mixtures, formed at oligomerization stage, using efficient titanium-magnesium ZN catalyst. We have shown that oligomerization of ethylene in α-olefin reaction media proceeds faster than in saturated hydrocarbons, providing the formation of 1-hexene, 1-octene, and branched C10 and C12 olefins; the composition and the ratio of the reaction products depended on the nature of PNP ligand. Oligomerizates were used in ZN polymerization 'as is', without additional treatment. Due to branched character of C10+ hydrocarbons, formed during oligomerization of ethylene, resulting polyolefins demonstrate higher low-temperature DR efficiency at low polymer concentrations (~1 ppm) in comparison with benchmark polymers prepared from the mixtures of linear α-olefins and from pure 1-hexene. We assume that faster solubility and more efficient solvation of the polyolefins, prepared using 'tandem' ethylene-based process, represent an advantage of these type polymers over conventional poly(1-hexene) and linear α-olefin-based polymers when used as 'winter' DRAs.
超高分子量聚α-烯烃被广泛用作石油和精炼石油产品管道输送的减阻剂（DRA）。聚烯烃减阻剂的合成基于高级α-烯烃的低温齐格勒-纳塔（ZN）聚合。基于1-己烯的减阻剂在室温下最有效，但在低温下通常会失去减阻活性。使用1-己烯与C8-C12线性α-烯烃的共聚物似乎可以解决低温减阻问题。目前的工作旨在开发聚烯烃减阻剂的两步合成法，该方法基于在高效铬/氨基二膦催化剂（Cr-PNP）存在下乙烯的选择性齐聚，然后使用高效钛-镁ZN催化剂聚合齐聚阶段形成的烯烃混合物。我们已经表明，乙烯在α-烯烃反应介质中的齐聚速度比在饱和烃中快，可生成1-己烯、1-辛烯以及支链C10和C12烯烃；反应产物的组成和比例取决于PNP配体的性质。齐聚产物未经额外处理，直接用于ZN聚合。由于乙烯齐聚过程中形成的C10+烃具有支链特性，与由线性α-烯烃混合物和纯1-己烯制备的基准聚合物相比，所得聚烯烃在低聚合物浓度（约1 ppm）下表现出更高的低温减阻效率。我们认为，使用基于乙烯的“串联”工艺制备的聚烯烃具有更快的溶解性和更有效的溶剂化作用，这使其在用作“冬季”减阻剂时比传统的聚（1-己烯）和基于线性α-烯烃的聚合物更具优势。
