Ziegler-Natta catalysis and propylene polymerization

Abstract

Transition metal catalyzed olefin polymerization is playing a key role in the development of novel versatile and environmentally friendly polymeric materials incluing both commodity and specialty polymers. Polyolefins, such as polypropylene (PP), combine low price and heat distortion temperature > 100°C with attractive mechanical proprties, e.g. strength, stiffness, impact resistance, low weight, corrosion resistance, and versatility in applications, ranging from automotive moldings to packaging and textile fibers. Moreover, polyolefins are compatible with most modern recycling processes. Upon heating above 400°C, polyolefins are readily degraded to form oil and gas which can be used as raw materials in petrochemical industry. Both crude oil and polyolefins are hydrocarbons with very similar molecular architectures, similar high energy content but different molar mass. In fact, PP and other polyolefins represent a solid modification of crude oil. Polyolefins meet the demand for sustainable development and help preserve valuable resources. As shown in Figure 1, crude oil is thermally cracked to form olefin monomers, which are polymerized using transition metal catalysts at low pressure in energy-efficient processes. Polymer properties can be tailored by means of catalysis and processing to meet the demands of highly diversified applications. After completing their product life cycle, polyolefins are recycled by remolding or by recovering the oil feedstock, which can be used to produce new olefin monomers, to substitute oil in the petrochemical industry or to serve as an oil substitute in steel mills or incinerators.