Environmentally Friendly Processes

In order to increase the sustainability of chemical processes, environmentally friendly solvents such as supercritical fluids (SCFs) are widely investigated. Han and coworkers studied the ethenolysis of ethyl oleate in SC C02 in relation with the phase behavior of the reaction mixture [62]. They carried out the ethenolysis reaction at 35°C in the absence of C02 and in the presence of C02 at three different pressures (50, 82, and 120 bar). The reaction in the absence of C02 reached equilibrium in 1 h at 80% conversion. The reaction rate in the presence of 50 bar of C02 was higher than without C02 and, at 82 bar, again increased with respect to 50 bar. However, when the pressure was increased to 120 bar, the reaction rate decreased. This effect was explained according to the variations on the phase behavior with the pressure an increase in the C02 pressure carried an increase of solubility of reactants, products, and C02, which produced a decrease of the viscosity of the reaction mixture. This positive effect was enhanced at 82 bar and was accompanied by an increase of selective solubility of the products in the vapor phase that further increased both reaction rate and conversion. The decrease of efficiency at 120 bar was related to an increase of the solubility of the reactants in the C02 phase. 

Application of metabolic engineering techniques can obviously result in higher yields and productivity, but also fewer side-products and improved stereospecificity. In contrast with competing chemical processes environmentally friendly production methods and renewable resources can often be used for production of high-value products. 

As for the presently employed process, a potential alternative to aqueous KOH or mineral acid is the use of a solid acid or base as catalyst for the dehydration of HEP, in order to make the process environmentally friendly [1,7]. 

However, this should pave the way for conducting polymers to be used as an alternative soluhon. Today, the major challenge for scientists working in the field of conduchve polymer-based products is to overcome any existing problems such that they may offer easily processed, environmentally friendly and stable conductive polymer-based functional coatings for general use. 

Thus, it is evident that catalysis has a key role in sustainable development (Keiski et al, 2010) and that a new era in catalysis has been opened. Catalysts have an enormous impact on industry and everyday life in making processes more efficient, increasing the operating profit and making processes environmentally friendly, economic and safe. 

Colella C 1999 Natural zeolites in environmentally friendly processes and applications Stud. Surf. Sol. Catal. 125 641-55... 

Apart from using an environmentally friendly solvent, it is also important to clean up the chemical reactions themselves by reducing the number and amount of side-products formed. For this purpose catalysts are a versatile tool. Catalysts have been used for thousands of years in processes such as fermentation and their importance has grown ever since. In synthetic oiganic chemistry, catalysts have found wide applications. In the majority of these catalytic processes, organic solvents are used, but also here the use of water is becoming increasingly popular . 

In several important cases, new synthetic strategies have been developed into new production schemes. An outstanding example of this is the production of an entire family of terpene derivatives from a-pinene (29), the major component of most turpentines, via linalool (3) (12). Many of these materials had been produced from P-pinene, a lesser component of turpentine, via pyrolysis to myrcene and further chemical processing. The newer method offers greater manufacturing dexibiUty and better economics, and is environmentally friendly in that catalytic air oxidation is used to introduce functionality. 

Transesterification. There has been renewed interest in the transesterification process for preparation of polycarbonate because of the desire to transition technology to environmentally friendly processes. The transesterification process utilizes no solvent during polymerization, producing neat polymer direcdy and thus chlorinated solvents may be entirely eliminated. General Electric operates a polycarbonate plant in Chiba, Japan which produces BPA polycarbonate via this melt process. 

Because sulfur suppHes, either as elemental sulfur or by-product sulfuric acid, have grown owiag to iacreased environmental awareness, demand for sulfur has decreased ia some consuming iadustries for the same reason. Industries such as titanium dioxide productions, which traditionally utilized sulfuric acid, have concerted to more environmentally friendly processes. In addition, many consumers who contiaue to use sulfuric acid are puttiag an emphasis on regenerating or recycling spent acid. 

In the CSIRO process, a reactive polyurethane prepolymer is appHed to a garment from perchloroethylene. The garment is then pressed and subsequendy steamed in an oven. A second polymer may sometimes be used in conjunction with the prepolymer. When this is employed, the process is termed the Serolan BAP Process (178). A number of alternative treatments are being investigated to achieve finishes that are more environmentally friendly (179). 

Some combing plants also produce shrink-resistant treated wool-top. The current process incorporates chlorination, and the appHcation of a shrinkproofing polymer. Chlorination is likely to be replaced soon by mote environmentally friendly treatments. 

The two fluids most often studied in supercritical fluid technology, carbon dioxide and water, are the two least expensive of all solvents. Carbon dioxide is nontoxic, nonflammable, and has a near-ambient critical temperature of 31.1°C. CO9 is an environmentally friendly substitute for organic solvents including chlorocarbons and chloroflu-orocarbons. Supercritical water (T = 374°C) is of interest as a substitute for organic solvents to minimize waste in extraction and reaction processes. Additionally, it is used for hydrothermal oxidation of hazardous organic wastes (also called supercritical water oxidation) and hydrothermal synthesis. 

Lacl<. of markets. The implementation of pollution-prevention processes and the production of environmentally friendly products will be of no avail if markets do not exist for such goods. As an example, the recychng of newspaper in the United States has resulted in an overabundance of waste paper without markets prepared to take advantage of this raw material. 

Corporate environmentalism is an evolving concept for environmental protection. In this case, business takes a pro-active stance independent of regulatory authorities. This can be in recognition of social responsibilities, but is more successful when compelled by competition in the market place. Thus, a hrm can conscientiously target environmentally aware consumers (through marketing environmentally friendly products or processes) or can be better placed for hnancial support from ethical investment funding bodies. 

Volume 125 Porous Materials in Environmentally Friendly Processes... 

Finally, an equally pressing need is for processes that are more environmentally friendly than those that currently use chromates, volatile solvents, etc. This is an area where the recently developed scientific tools described in this and other chapters will play a major role in assuring that the results are not only greener but are also just as effective or more so than currently used methods. 

Innovative chemical synthesis procedures have been proposed as offering potential for economical and environmentally friendly routes to a variety of chemicals. These novel chemical reactions also offer potential for increasing the inherent safety of processes by eliminating hazardous materials, eliminating chemical intermediates, or allowing... 

Haggrn, J. Innovation in Catalysis Create Environmentally Friendly THE Process Chemical and Engineering News, April 3, 1995, pp. 20-23. 

A first obvious consequence of such considerations is that we should not only look at the costs of the product from an economic point of view, but that we must consider the costs of the production process in a broader sense. We must take into account the raw materials used, the amount of energy invested and the possibility to design alternatives, more environmentally friendly processes. In other words, we should not only look at the desired product, but we must consider the total life cycle of the product The design of a production process taking into account these aspects is often referred to as integral life cycle management. 

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