Polyolefin co catalysts and electron donors
Polyolefin is a type of polymer material with the largest production and widest application, usually obtained by polymerization of olefin monomers under the action of catalytic systems. As is well known, the key to synthesizing high-end polyolefins lies in selecting appropriate catalytic systems. So far, the most commonly used catalysts in industry are supported catalysts, which generally consist of the following components: main catalyst, co catalyst, electron donor, and carrier. The co catalyst is an auxiliary component of the catalyst, which itself has no activity, but can change the physical structure and chemical form of the main catalyst, thus improving the performance of the catalyst. The main function of electron donors is to change the activity of catalysts, affect the regularity and crystallinity of polypropylene, control the molecular weight, molecular weight distribution, and other properties of polymers.
Co catalysts: Currently, there are two main types of metallocene catalyst additives: one is alkylaluminoxane (MAO); Another type is organic boron compounds. The discovery of organic boron compounds not only improves the activity of catalysts, but also solves the problem of high MAO dosage and cost. During the reaction process, the non coordinating anions of organic borides can form ion pairs with the cationic active center, thereby stabilizing the cationic active center.
Electron donor: Electron donors are divided into internal donor Di and external donor De. The former refers to being added during the preparation of solid catalysts, while the latter is added in situ during polymerization, with a synergistic effect between the two. The most commonly used electron donors include aromatic esters, ethers, amines, and alkanesilic compounds. In recent years, a new generation of Ziegler Natta supported efficient catalysts have been synthesized using 1,3-diether compounds as internal electron donors. One of the characteristics of this catalyst is that it remains highly active without the need for external electron donors, resulting in highly structured polypropylene.
Product application
In the polymerization process of ethylene and 1-hexene, different co catalysts were added for comparison (see the figure below), Journal of molecular catalysis. 2015, 29, 3)， Among them, [Ph3C] [B (C6F5) 4] and [HNMe2Ph] [B (C6F5) 4] exhibit good catalytic activity, resulting in a narrower molecular weight distribution of polyolefins with a density between 0.91 and 0.92 g/mL, belonging to the category of metallocene linear low-density polyethylene (mLLDPE), which makes the material exhibit better performance.
Yanfeng Technology can provide a series of products for polyolefin co catalysts and electron donors, which play a crucial role in improving catalytic activity, improving polyolefin homogeneity, regularity and other indicators. This project was approved in 2018 and has a production and supply capacity ranging from kilograms to tons. It can also be customized according to customer needs.