Processes for Large-Scale Applications

The fourth generation process for large-scale application still has to be selected from the potential processes that have been nominated . In the chapters to follow several of these candidates will be discussed. The fourth generation will concern higher alkenes only, since for propene hydroformylation there are hardly wishes left [13], Many new phosphite-based catalysts have been reported that will convert internal alkenes to terminal products [6,7,14] and recently also new diphosphines have been reported that will do this [15,16,17],... 

This chapter discusses the present status of microbial SCP production from agricultural wastes and describes some of the technical and economical problems related to the production processes that must be overcome for large-scale application to be possible. 

Polyester chemistry is the same as studied by Carothers long ago, but polyester synthesis is still a very active field. New polymers have been very recently or will be soon commercially introduced PTT for fiber applications poly(ethylene naph-thalate) (PEN) for packaging and fiber applications and poly(lactic acid) (PLA), a biopolymer synthesized from renewable resources (corn syrup) introduced by Dow-Cargill for large-scale applications in textile industry and solid-state molding resins. Polyesters with unusual hyperbranched architecture also recently appeared and are claimed to find applications as crosstinkers, surfactants, or processing additives. 

Bioprocesses for the removal of nitrogen oxides from polluted air are an interesting alternative [58], but current reaction rates are still too low for large-scale applications. Advanced biological processes for the removal of NO from flue gases are based on the catalytic activity of either eukaryotes or prokaryotes, e.g. nitrification, denitrification, the use of microalgae and a combined physicochemical and biological process (BioDeNO ). 

The industrial use of 1,3-dienes and of their electrophilic reactions has strongly stimulated the field in recent years. Because of the low cost of butadiene, abundantly available from the naphtha cracking process, very large scale applications in the synthesis of polymers, solvents and fine chemicals have been developed, leading to many basic raw materials of the modem chemical industry. For example, the primary steps in the syntheses of acrylonitrile and adiponitrile have been the electrophilic addition of hydrocyanic acid to butadiene24. Chlorination of butadiene was the basis of chloroprene synthesis25. 

According to researchers, furnaces for ceramic immobilization processes typically cost less than 1000 (D16044B, p. 155). According to the researchers, the SYNROC approach is only cost effective for large-scale applications (a large-scale application is assumed to produce 30-cm-diameter disks, each weighing approximately 30 kg). Cold press applications of the SYNROC process are more cost effective (D160429, pp. 255-256). No cost information is available for the Ceramification and SMITE processes. 

Naturally, there exist a variety of membrane separation processes depending on the particular separation task [1]. The successful introduction of a membrane process into the production line therefore relies on understanding the basic separation principles as well as on the knowledge of the application limits. As is the case with any other unit operation, the optimum configuration needs to be found in view of the overall production process, and combination with other separation techniques (hybrid processes) often proves advantageous for large-scale applications. 

The PGSS process has several advantages which favour its use for large scale applications. This process has promise for the processing of low-melting, highly viscous, waxy, and sticky compounds, even if the obtained particles are not of submicron size. The process already runs in plants with a capacity of some hundred kilograms per hour. 

As a consequence of the development of the N-methylmorpholine N-oxide (NMO) and later the potassium ferricyanide cooxidant systems the amounts of osmium tetroxide and chiral ligand used in the reaction could be considerably reduced. However, the method remains problematic for large-scale applications. The cooxidants for Os(VI) are expensive and large amounts of waste are produced (Table 5). Lately, several groups have addressed this problem and new reoxidation processes for osmium(VI) species have been developed. 

Black, N. R, ASAM Alkaline sulfite pulping process shows potential for large-scale application. Tappi J1991, 74 (4), 87-93. 

Technology for large-scale application of chemical reduction is well developed. The reduction of residual chlorine in a chlorination or superchlorination process system is termed dechlorination, which is the most common process in municipal water and wastewater treatment. The reduction of chromium waste by sulfur dioxide is another classic process and is in use by numerous plants employing chromium compounds in operations such as electroplating. 

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