PTQ Q4 2024 Issue

First commercialised in the 1930s, the growth of the polyolefin market share over the decades is due to the discovery of and subsequent improvements to catalysts. Ziegler-Natta-type catalysts, introduced in the 1950s, are still commonly used today for the production of PE and PP. With PE, Ziegler-Natta catalysts account for almost 45% of all polymerisation processes; for PP, it is 95%. These popular catalysts, however, need a support to achieve their best performance, which is where magnesium ethoxide excels. Marrying performance and cost-effective- ness, this material can assist companies with their sustain- ability goals. Evolution of Ziegler-Natta catalysts The second generation of catalysts for polyolefin production was introduced in the 1970s when scientists discovered the incorporation of magnesium species into the Ti-Al (titanium- organoaluminium) Ziegler-Natta catalyst. Magnesium signif - icantly increased catalyst activity and increased the catalysts’ capability to incorporate a second monomer, a high α -olefin with four or six carbon atoms, into PE chains. Ti-Mg-Al (titanium-magnesium-organoaluminium) Ziegler- Natta catalysts revolutionised the polyolefin industry. Current polymerisation processes have been designed based on this version of catalyst. Polyolefin production can now take place with monomer and comonomer in the presence of Ziegler-Natta catalysts without the need for diluent, significantly reducing the environmental impact. Additionally, the higher catalyst activity in the range (20,000-60,000 kg polyolefin)/(kg cat) leaves a minimal amount of metal residue in the resin, thereby eliminating the need for residue removal steps. For PP production, a promoter known as the internal donor was incorporated into the aforementioned Ti-Mg-Al catalyst to selectively produce the useful grades of PP, isotactic PP (iPP), in combination with a second promoter known as the external donor. Continued benefits of magnesium ethoxide The magnesium used in Ziegler-Natta catalyst production takes two forms: magnesium chloride (MgCl₂) and magne - sium alkoxide. The latter is mainly in the form of magnesium ethoxide (MgE, for short). In the finished Ziegler-Natta cat - alyst, most magnesium species exist in the form of MgCl₂ through a series of chemical transformations. Looking at propylene polymerisation, MgCl₂ serves as the catalyst support and is still part of the catalyst’s active com- ponents. The main composition in the finished catalysts, it utilises its unique crystal structure to disperse titanium and the internal donor, to make a highly active and highly selective catalyst for the production of desired iPP. Evonik provides proprietary olefin polymerisation catalyst compo - nents for the manufacture of polyolefin catalysts, compris - ing both supports and donors. Catylen S A precursor to a variety of ethylene and propylene polymeri- sation catalysts, granular MgE – Catylen S 100 series is a

FCC Equilibrium catalyst: Added Fe

0.2 0.1 0.4 0.3 0.6 0.5 0.8 0.7 1.2 0.9 1 1.1

800 ppm

Na+V Normalised FACT

equivalent of only 9,000-10,000 ppm. In this case, cata- lyst activity is not affected outside of the normal variabil- ity baseline. Thus, by keeping steady-state Fe equivalent below 10,000 ppm, there is minimal catalyst activity impact beyond effects from other associated contaminants such as V. Even when Fe levels rise quickly, catalyst activity can still be maintained by increasing the catalyst addition rate to keep steady-state equivalent Fe to below 10,000 ppm. Controlled activity and operation are key to the future of operating residual feedstocks. The yield objectives for this case study, such as coke, delta coke, slurry, and other unit yields, were achieved while processing this high Fe feedstock. Figure 2 Activity response to sudden (orange) and steady (grey) ramps in Fe, with Na and V effects removed

BASF Contact: kevin.yao@basf.com

Polyolefins consisting of polyethylene (PE) and polypropylene (PP) belong to the top five groups of plastic materials produced globally. Two hundred and twenty million tons of polyolefin plastics are produced annually. This versatile thermoplastic boasts a wide range of end-use applications, spanning pipes, containers, automotive parts, medical devices, and more. Pursue sustainability and improve catalyst performance with magnesium ethoxide when producing polyolefins

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PTQ Q4 2024