The Role of Catalysis in Determining Men’s Quality of Life

Modern civilization, whose spectacular development took place in the second half of XX century as the result of scientific and information revolution has six characteristic features: (1) it is a mass civilization, (2) it is mobile, (3) it is global, (4) it is free of the spectre of famine, (5) it is built on informatics, (6) human lifespan is steadily prolonged. In order to achieve these goals it was necessary to invent thousands new materials and to find out methods of their fast and cheap production in large quantities. The unique possibility of the fast and selective production of the desired chemical molecules, required to obtain a material with defined properties, is offered by catalysis. Catalysis comprises technological processes of the largest scale, such as catalytic cracking of billions tons of crude oil per year and smallest scale enzymatic reactions with micrograms of product formed with 100% chemo-, regio- and stereoselectivity. With the rapidly growing earth’s population increasingly important becomes not only the production of materials needed in our modern society, but also the destruction of undesired by-products of its activities, making the application of catalysis to pollution control one of important tasks. The progress of catalysis, both science and technology, was in the last 50 years driven by the development in five fields: (1) new materials, particularly those based on the principle of molecular imprinting (use of templates), (2) application of new surface science techniques to identify active sites and surface reaction intermediates, (3) quantum chemical modeling of elementary steps of catalytic reactions, (4) design of new reactors, (5) development of computational catalysis, (6) development of new ways for carrying catalytic reactions, (7) biocatalysis using enzymes, modified by mutagenesis and recombination techniques to make them selective and active in conditions of the desired technological process. Application of molecular sieves, catalytic antibodies, metallocene catalysts, asymmetric catalysis, fuel cells, control of automotive exhaust are described and pending change of the paradigm of catalysis is discussed.     

Syndiotactic Polystyrene Materials

The ability of an engineering plastic material to maintain properties at increased temperature is critical in many applications. Here is discussed how recent developments in catalyst technology have led to the ability to produce syndiotactic polystyrene (See Figure), the regularly alternating arrangement of pendant phenyl groups giving rise to a crystalline material with well‐structured spherulitic morphology and improved heat performance.     

Recent transition metal catalysts for syndiotactic polystyrene

Syndiotactic polystyrene has attracted much interest in scientific and industrial research after its first synthesis in 1985 and has led to a fast commercialization of this polymer. The catalyst systems used for this coordination polymerization of styrene are a key point in this development to provide high polymerization activities and syndiotacticities of the polymers obtained.This literature review gives a comprehensive overview on the recent transition metal catalysts comprising the literature since about 2000 and especially on the transition metal complexes investigated in the syndiospecific homopolymerization of styrene. It includes the polymerization activity of the catalysts, the syndiotacticity of the polymers received as well as the discussion of the relationships between catalyst structure and polymerization activity. The complex-coordination mechanism of the syndiospecific polymerization of styrene is summarized in general at the beginning.The review of the recent transition metal catalysts for the syndiospecific styrene polymerization includes transition metal complexes, cocatalysts (methylaluminoxanes and boron compounds), activators and chain transfer agents, and supported and heterogenized catalysts. Transition metal complexes contain group 4 transition metal complexes (mono- and bis-cyclopentadienyl complexes, metal complexes of other ring systems such as indenyl, fluorenyl and other complexes, di- and multi-nuclear complexes, and non-metallocene complexes), and metal complexes of other transition metals (groups 8–10, rare earth metals, and others). The chapter on mono-cyclopentadienyl complexes demonstrates an overview on the investigations using unsubstituted cyclopentadienyl and pentamethylcyclopentadienyl complexes, on the influence of the variation of the structure of the cyclopentadienyl ligand, and on the effect of the variation of ancillary complex ligands besides cyclopentadienyl.This summary also considers recent developments in the preparation of new transition metal complexes based on the synthesis of completely novel π-ligands of the half-metallocenes, the success in attaining high syndiospecificities with transition metal complexes based on rare earth metals, the coordination polymerization in aqueous systems, the syndiospecific living polymerization, and new activators for the catalysts, with regard to syndiotactic polystyrenes.     

Copolymerization of propylene and norbornene with different metallocene catalysts

Propylene and norbornene were copolymerized by metallocene/MAO catalysts. The organometallic compounds rac-[Me₂C(Ind)₂]ZrCl₂ (1) and [Me₂C(Cp)(Flu)]ZrCl₂ (2), [Ph₂C(Cp)(2,7-di^tBuFlu)]ZrCl₂ (3) and [Me₂Si(3-^tBuCp)(N^tBu)]TiCl₂ (4) were used to catalyze polymerization series, in which the influence of the molar fraction of norbornene in the feed and of the polymerization temperature were investigated in detail. The obtained polymers, which exhibit a wide range of properties with glass transition temperatures above 200 °C, were characterized by ¹³C NMR spectroscopy, differential scanning calorimetry and gel permeation chromatography techniques.In this article, the emphasis is placed on the copolymerization behaviour of the catalysts and the properties of the obtained polymers, while other articles concentrate on NMR investigations of propylene/norbornene copolymers.     

Recent Research Progress in Burning Rate Catalysts

Burning rate catalysts are one of the most important components of rocket propellants and are able to enhance solid propellant burning rates. There are several kinds of burning rate catalysts such as nanometal burning rate catalysts, nanometal oxide burning rate catalysts, compound burning rate catalysts, ferrocene and its derivatives burning rate catalysts, and so on. This article reviews the recent research processes in burning rate catalysts.