Production routes

The basic Solvay process remains the dominant production route for soda ash. Its continued success is based on the raw matedals, salt and limestone, being more readily available than natural alkaU. AH soda ash processes are based on the manipulation of saline phase chemistry (6,7) an understanding of which is important both to improving current processes and to the economic development of new alkaU resources. 

Liquid-Phase Oxidation. Liquid-phase catalytic oxidation of / -butane is a minor production route for acetic acid manufacture. Formic acid (qv) also is produced commercially by Hquid-phase oxidation of / -butane (18) (see HYDROCARBON OXIDATION). 

Some alkylphenol appHcations can tolerate "as is" reactor products, most significantly in the production of alkylphenol—formaldehyde resins. These resins can tolerate some of the reactant and by-product from the alkylphenol reactor because they undergo purification steps. This resin production route has both capital and operating cost advantages over using purer alkylphenol streams as feedstock. For these savings, the resin producer must operate the process in such a way as to tolerate a more widely varying feedstock and assume the burden of waste disposal of some unreactive materials from the alkylphenol process. 

The principal iadustrial production route used to prepare fatty amines is the hydrogenation of nitriles, a route which has been used since the 1940s. Commercial preparation of fatty amines from fatty alcohols is a fairly new process, created around 1970, which utilizes petrochemical technology, Ziegler or Oxo processes, and feedstock. 

The ketene—crotonaldehyde route through polyester with various modifications and improvements is reportedly practiced by Hoechst Celanese, Cheminova, Daicel, Ueno, Chisso, Nippon Gohsei, and Eastman Chemical Company. Differences in thein processes consist mosdy in the methods of polyester splitting and first-stage purification. Production of the potassium salt can be from finished sorbic acid or from a stream in the sorbic acid production route before the final drying step. Several patents on the process for producing sorbic acid and potassium sorbate from this route are given in the hterature. 

Two pigment production routes ate in commercial use. In the sulfate process, the ore is dissolved in sulfuric acid, the solution is hydrolyzed to precipitate a microcrystalline titanium dioxide, which in turn is grown by a process of calcination at temperatures of ca 900—1000°C. In the chloride process, titanium tetrachloride, formed by chlorinating the ore, is purified by distillation and is then oxidized at ca 1400—1600°C to form crystals of the required size. In both cases, the taw products are finished by coating with a layer of hydrous oxides, typically a mixture of siUca, alumina, etc. 

Biological. Several recent patents have claimed the production of ethylene oxide from a wide variety of raw materials using enzymatic catalysts (221—224). However, no commercial production routes based on biological mechanisms have been proposed. 

The design is viable only if it can be produced economically. The choice of production and fabrication method is largely determined by the choice of material. But the production route will also be influenced by the size of the production run, and how the component will be finished and joined to other components each class of material has its own special problems here they were discussed in Chapters 14, 19, 24 and 25. The choice of material and production route will, ultimately, determine the price of the product, so a second major iteration may be required if the costing shows the price to be too high. Then a new choice of material or component design, allowing an alternative production path, may have to be considered. 

As in the previous group, a potentially productive route into C7-ring chemistry is provided by the reduction of a metal halide with Na/Hg in thf in the presence of cycloheptatriene. WithMoCl5, [Mo(p -C7H7)(p -C7H9)] is produced and a variety of derivatives have already been obtained. 

As formerly mentioned, the whole Dryex system can be sized over a wide range of production capacities since it is constituted by two main sections, each one characterized by high flexibility, the specific size of the drying/concentra-tion section can be decided with respect to the production rate of the first section as well as to the specific production route and need of the surfactant makers. By taking these factors into account, the drying/concentration equipment can be easily and conveniently coupled with already existing and running sul-fonation/sulfation plants to increase their industrial potential. 

Scheme 1.1 Atom economy for maleic anhydride production routes...

Industrial chemical processes are determined by recipe and production route. The recipe is the specification of a sequence of processing steps for the transformation of raw materials into the desired product(s). Specifications include quantity and quality of raw materials, composition of feeds, sequence of additions to the reaction zone, rate of dosing, temperature-time dependencies, pressures, etc. The production route also includes the specification of equipment in which processing steps are performed. 

In addition to the assumption that one production route exists for each product, the following simplifying assumptions are made (after Suhami and Mah, 1982) ... 

In specific applications, it is critically important to know which isomer is produced in a particular situation in order to ascertain its further reactivity. Indeed, further reactivity, in the form of rate coefficients and product ion distributions, both identifies which reactions generate the same isomeric forms and gives information to enable the isomeric forms to be identified (often by determining the energetics and comparing them with theoretical calculations). One such application is to molecular synthesis in interstellar gas clouds. In the synthesis of the >115 molecules (mainly neutral -85%) detected in these clouds,14 a major production route is via the radiatively stabilized analog of the collisional association discussed above,15 viz. ... 

In these studies the quoted production routes were not unique. For example, with He/CH3Br/CH3OH mixtures, a significant amount of (CH3)2OH+ was directly produced by the reaction ... 

Domier has developed a production route for continuous fiber-reinforced ceramics based on the impregnation and pyrolysis of Si-polymers. This process is related to the manufacturing of fiber-reinforced plastics and allows the cost-effective production of large and complex CMC-structures. 

McGurk, K. 2003. From 1-heptene to 1-octene A new production route. Paper presented at the South African Chemical Engineering Congress, Sun City, P082. 

The complete branch for formation of bis(allyl),A-cA-dodecatrienediyl-Ni11 forms is shown to be disabled, because of (i) the unfavorable coupling of two czj-butadienes along Tb -> 2b together with a slow isomerization via r 3-antiy]1 (C3) isomers of TSisoPb], which prevents a sufficient concentration of rx -anti,r l(Cl),A-cis precursors 2b, and (ii) owing to a kinetically impeded butadiene insertion into the p3-ararz-ailyl-Nin bond along 2b 7b. Consequently, the all-c-CDT production route is entirely precluded. 

Figure 3.2 Summary of hydrogen production routes from biomass. (Source Milne, T.A. et al. Hydrogen from Biomass State of the Art and Research Challenges, NREL, IEA/H2/TR-02/001).

Low molecular weight New production route Well-known Rigorous Amino acid 6-APA... 

High molecular weight substance New production route Fairly well-known Extensive Human hormones, e.g., hGH, hPTH... 

Many companies have said that if an alternative route to a derivative was economically justifiable that would be used in preference to a chlorine route. This has already had an impact on the technology of choice in some production routes to isocyanates, polycarbonate, propylene oxide and epichlorohydrin. 

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