Homogeneous Catalysis

Mechanisms and Industrial Applications

Sumit Bhaduri, Doble Mukesh

• Publisher: Wiley
• Year: 2014
• ISBN:
  9781118872512
• Edition: 2
• Topic: Physical Sciences
• Subtopic: Organic Chemistry

Over the last decade, the area of homogeneous catalysis with transition metal has grown in great scientific interest and technological promise, with research in this area earning three Nobel Prizes and filing thousands of patents relating to metallocene and non-metallocene single site catalysts, asymmetric catalysis, carbon-carbon bond forming metathesis and cross coupling reactions.
This text explains these new developments in a unified, cogent, and comprehensible manner while also detailing earlier discoveries and the fundamentals of homogeneous catalysis. Serving as a self-study guide for students and all chemists seeking to gain entry into this field, it can also be used by experienced researchers from both academia and industry for referring to leading state of the art review articles and patents, and also as a quick self-study manual in an area that is outside their immediate expertise. The book features:
•Topics including renewable feed stocks (biofuel, glycerol), carbon dioxide based processes (polycarbonates), fluorous solvents, ionic liquid, hydroformylation, polymerization, oxidation, asymmetric catalysis, and more
•Basic principles of organometallic chemistry, homogeneous catalysis, and relevant technological issues
•Problems and answers, industrial applications (case studies), and examples from proven industrial processes with clear discussions on environmental and techno-commercial issues
•Extensive references to cutting edge research with application potential and leading patents
•Tables and illustrations to help explain difficult concepts

Chapter 1
Chemical Industry and Homogeneous Catalysis

1. 1.1 Feedstocks, Fuels, and Catalysts
2. 1.2 Crude Oil to Gasoline and Basic Building Blocks by Heterogeneous Catalysts
   1. 1.2.1 Cracking Reactions
   2. 1.2.2 Hydrodesulfurization Reactions
3. 1.3 Basic Building Blocks to Downstream Products by Homogeneous Catalysis
4. 1.4 Comparison among Different Types of Catalysis
5. 1.5 Catalyst Recovery
6. 1.6 Environmental Issues
   1. 1.6.1 Background
   2. 1.6.2 Biofuel, Ethanol, and Glycerol
   3. 1.6.3 Biodegradable Plastics
   4. 1.6.4 Hydrogen and Carbon Dioxide
7. Problems
8. Bibliography

The chemical industry manufactures a very large number of products for different uses. In industrial parlance, the products are often classified under different categories such as polymers and resins, fine chemicals, flavors and fragrances, and pharmaceutical intermediates. Some of these such as plastics are produced in millions of tons, while some others less than a few tons per year. As we will see, homogeneous catalysis plays an important role at both these extremes.

It is estimated that the chemical industry contributes about 10% to the world's total trade and about 5% to the total income. It employs about 10 million employees and generates a combined turnover of more than 3 trillion dollars including from pharmaceuticals. The manufacturing processes of many of the products mentioned are critically dependent on the use of catalysts. In recent years, catalytic research has gained additional momentum for two main reasons.

First, many existing chemical products and processes have been found to have adverse effects on the environment and this has spurred search for alternatives that are more environment friendly. In this approach, catalysis plays a pivotal role. Second, catalysts help to save energy and to avoid the formation of unwanted products. Thus the use of catalysts for new chemical processes makes them commercially attractive.

1.1 Feedstocks, Fuels, and Catalysts

The manufacture of all organic chemicals and carbon-based polymers requires a carbon-containing precursor, i.e., a feedstock. The main feedstocks of the chemical industry are crude oil, other oils that are difficult to process, coal, and natural gas. These feedstocks are also used to meet much of today's worldwide energy requirements. To emphasize their geological origin and finite availability, crude oil, coal, etc., are referred to as fossil fuels.

Crude oil is currently the main feedstock used by the oil industry to manufacture processed petroleum products such as petrol, diesel, kerosene, and aviation fuel. Of the total amount of available crude oil, only about 10% is used for the manufacture of chemicals and the rest are used as fuels. Basically, crude oil is a complex physical mixture of many hydrocarbons where the number of carbon atoms per molecule could be as high as 60 or more.

The phenomenological definition of a catalyst is a substance that accelerates a chemical reaction but in the process does not undergo any chemical change itself. Catalysis plays a critical role not just in the oil and chemical industries but also in the manufacture of many inorganic chemicals, pollution abatement, and fuel cells. At a rough estimate, more than 75% of all existing industrial chemical transformations and 90% of newly developed processes involve the use of catalysts.

In most of these applications, the catalysts are insoluble solids and are called heterogeneous catalysts. In this book we deal almost exclusively with homogeneous catalytic processes. These are processes in which soluble catalysts are used and the catalytic reactions take place in the liquid phase. However, both heterogeneous and homogeneous catalysts operate by reducing the energy required to bring about the reorganization and changes of molecular structures of the reactants.

At a molecular level, most homogeneous catalysts are well characterized in terms of their chemical composition and structure. As all the molecules of a given homogeneous catalyst have the same structure, they facilitate breaking, forming, and reorganization of chemical bonds of the reactants in an identical manner. In contrast, in heterogeneous catalytic processes the molecules of the gaseous or liquid reactants are adsorbed on the surfaces of the solid catalysts. Unlike homogeneous catalysts, solid surfaces consist of an infinite array of ions or atoms with different types of local structures, i.e., potential reaction sites. To emphasize the homogeneity at a molecular level, some homogeneous catalysts are also called single site catalysts.

1.2 Crude Oil to Gasoline and Basic Building Blocks by Heterogeneous Catalysts

To put the importance of homogeneous catalysis in perspective, we first present a very brief summary of the basic processes of the petrochemical industry. Most of these processes are catalytic, and the goal is to convert crude oil to gasoline, other fuels, and basic building blocks for downstream chemicals.

Crude oil is composed of many hydrocarbons that differ in the number of carbon atoms per molecule. As the number of carbon atoms increases, the boiling point (BP) also increases. The BP and the number of carbon atoms per molecule in crude oil typically range from <30°C to >610°C and 1 to >60, respectively. By subjecting crude oil to fractional distillation, the major components such as crude gasoline (~5–12), naphtha (~8–12), kerosene (~11–13), and diesel (~13–17) are separated. The approximate number of carbon atoms of the hydrocarbons present in these components is given in the parentheses.

As shown in Figure 1.1, in the oil and petrochemical industry, the catalytic...