Role of Industrial and Biological Catalysts

ROLE OF INDUSTRIAL AND BIOLOGICAL CATALYSTS 6.2.1 Definition of Catalysts... 

Copper occims in foin oxidation states, zero, monovalent, divalent, and trivalent (f). Its divalent species is the most common and most stable. Copper, particularly copper(I) and its complexes, is a catalyst in many industrial and biological processes. The majority of reactions in which copper is used as a catalyst, usually redox processes, involve monovalent copper as an intermediate amd often as the initiator of the catalytic process. The role of copper in biological processes as well as the green chemistry desire to perform catalytic processes in water stresses the importance of Cu(I) in aqueous media. 

Transition metal catalysts, specifically those composed of iron nanoparticles, are widely employed in industrial chemical production and pollution abatement applications [67], Iron also plays a cracial role in many important biological processes. Iron oxides are economical alternatives to more costly catalysts and show activity for the oxidation of methane [68], conversion of carbon monoxide to carbon dioxide [58], and the transformation of various hydrocarbons [69,70]. In addition, iron oxides have good catalytic lifetimes and are resistant to high concentrations of moisture and CO which often poison other catalysts [71]. Li et al. have observed that nanosized iron oxides are highly active for CO oxidation at low tanperatures [58]. Iron is unique and more active than other catalyst and support materials because it is easily reduced and provides a large number of potential active sites because of its highly disordered and defect rich structure [72, 73]. Previous gas-phase smdies of cationic iron clusters have included determination of the thermochemistry and bond energies of iron cluster oxides and iron carbonyl complexes by Armentrout and co-workers [74, 75], and a classification of the dissociation patterns of small iron oxide cluster cations by Schwarz et al. [76]. 

The epoxidation of olefins plays an important role in the industrial production of several commodity compounds, as well as in the synthesis of many intermediates, fine chemicals, and pharmaceuticals. The scale of production ranges from millions of tons per year to a few grams per year. The diversity of catalysts is large and encompasses all the known categories of catalyst type homogeneous, heterogeneous, and biological. 

Manganese is tlie third most abundant transition element 1]. It is present in a number of industrial, biological, and environmental systems, representative examples of which include manganese oxide batteries [2] the oxygen-evolving center of photosystem II (PSII) [3] manganese catalase, peroxidase, superoxide dismutase (SOD), and other enzymes [4, 5] chiral epoxidation catalysts [6] and deep ocean nodules [7]. Oxidation-reduction chemistry plays a central role in the function of most, if not all, of these examples. 

Nanosized particles and porous materials play an important role in many technological applications. They have been used widely as biological sensors, integrated electronic devices, catalyst supports, and adsorbents for detoxification of industrial effluents and domestic water, decoloring of processing water, and purification of pharmaceuticals and proteins. In Chapter 3, Xu et al. showed some typical applications of functionalized superparamagnetic particles in biological cell separation and industrial effluent detoxification. Porous media, on the other hand, constitute an... 

Cobalt imparts to sihcate melts intense blue colors used in glassmaking, glazes, and enamels. From a biological point of view, cobalt is one of the world s essential elements. Actually, as one of the 27 elements that are essential to humans, cobalt occupies an important role as the central component of cyanocobalamine (vitamin B12). Industrially, two grades of commercially pure cobalt are available on the market (i) cobalt (99.3 wt.% Co), used for noncritical met urgical applications, in the chemical industry, and for permanent magnets and catalysts, while (ii) cobalt (99.8 wt.% Co) is used in rechargeable lithium ion batteries and fine chemicals. 

Biological reactions that involve microorganisms and enzyme catalysts are pervasive and play a crucial role in the natural world. Without such bioreactions, plant and animal life as we know it simply could not exist. Bioreactions also provide the basis for production of a wide variety of pharmaceuticals and healthcare and food products. Other important industrial processes that involve bioreactions include fermentation and wastewater treatment. Chemical engineers are heavily involved with biochemical and biomedical processes. In this section we present a dynamic model for a representative process, a bioreactor operated in a semi-batch mode. Additional biochemical and biomedical applications appear in other chapters. 

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