Establishment of De Facto Standard Catalysts in the Polypropylene Industry

Abstract

Polypropylene (PP) has become an indispensable material in our daily lives. Annual worldwide production of PP is now more than 30000000 tons and is predicted to grow at an annual rate of about 6% during the first decade of the 21st century. Commercial production of PP began in 1957 with the use of TiCl(3) catalysts established by Ziegler and Natta. However, the low activities and low stereospecificities of the catalysts resulted in large amounts of catalyst residue and atactic PP in the product, necessitating steps for their removal in commercial production. As a means of finding appropriate catalysts, we developed MgCl(2)-supported TiCl(4) catalysts, which basic concept was introduction of organic compounds onto the inorganic crystal catalyst surface. This addition led to remarkable enhancements in stereospecificity with extremely high activity. Use of the new catalysts enlarged and simplified the PP production process by eliminating the steps previously required for removal of catalyst residue and atactic PP. In addition, it greatly improved the properties of the PP, enabling a much wider range of PP applications by replacing metal and engineering plastics with the highly stereoregular PP. Therefore, these catalysts helped the rapid establishment of the current PP industry and now play a major role in production. The latest MgCl(2)-supported TiCl(4) catalyst is providing precise control of the isotactic PP structure. Future expectations for this type of catalyst are to acquire a single-site nature and to contribute to the creation of a new class of hybrid materials.

FI Catalysts for Olefin Polymerization—A Comprehensive Treatment

“…Since the late 1960s, MgCl 2 has been employed as a support of the Ti-based Ziegler−Natta catalysts. The most advanced heterogeneous MgCl 2 -supported Ti catalysts have reached an astoundingly high performance level in terms of activity, stereoselectivity for propylene polymerization, and control of the polymer morphology, and they are still the most widely used catalysts in the polyolefin industry. ,, During this modern period, a wide variety of technologies have been developed to prepare a MgCl 2 catalyst support with a large specific surface area and controlled morphology, despite the fact that, under normal conditions, MgCl 2 is a highly crystalline solid with very low surface area. It should be noted that MgCl 2 was also found to significantly enhance the rate constant of olefin insertion reactions, thus serving as an activator as well as a catalyst support.…”

Mechanistic Analysis of the Fire Performance of a Fire Retardant System

“…In this work, some of the materials pyrolyzed over more than one step, therefore the thermogram was divided into separate stages and each stage was dealt with as a single degradation process, and analyzed using Equation (1).…”

“…INTRODUCTION POLYPROPYLENE (PP) IS one of the most commonly used polymers today. Annual worldwide production in 2003 was more than 30 million tonnes [1] and is currently around 39 million tonnes [2]. It is broadly used and its performance and applicability has been enhanced by formulating with a variety of additives including fire retardants to enhance its fire performance and light stabilizers to improve its UV and thermal stability.…”

Titanium−Manganese Compound with a Chiral Mn3Ti Center

“…Although more than 50 years have passed since its “discovery”, Ziegler−Natta (Z−N) catalysis remains one of the most important and profitable processes . Despite its long history, it is also the fastest growing segment of the polymer industry . Several generations of Z−N catalysts have been developed. , Each generation contributed with a higher productivity of the process and quite often significant improvement of the stereospecifity of the α-olefin polymerization .…”