Acetic acid operating conditions

The explosive limits for atmospheric and for reactor conditions. For example, for the oxidation of acetaldehyde to acetic acid, explosive conditions occur outside the operating window. However, for some processes during startup, the reactor passes through the explosive conditions to reach the operating window. 

For the conjugate-addition reactions which produce the prostaglandin skeleton, it is necessary to block all the hydroxy and carboxy functions. The ether blocking groups which we have found useful include tetrahydropyranyl (THP) and trime-thylsilyl (TMS). Both of these ethers are readily cleaved with aqueous acetic acid under conditions compatible with the stability of 11-oxy PGE derivatives. These same two groups also serve to esterify the carboxy function. Thus, a hydroxyacid can be blocked in one operation by conversion to a "bis-THP" or "bis-TMS" derivative. Alkyl esters also may be used, but the alkyl ll-hydroxy-9-ketoprostanoates produced can not be converted to the free acids by chemical means. 

The kinetics of nitration of anisole in solutions of nitric acid in acetic acid were complicated, for both autocatalysis and autoretardation could be observed under suitable conditions. However, it was concluded from these results that two mechanisms of nitration were operating, namely the general mechanism involving the nitronium ion and the reaction catalysed by nitrous acid. It was not possible to isolate these mechanisms completely, although by varying the conditions either could be made dominant. 

The synthesis of chlorarul [118-75-2] (20) has been improved. The old processes starting from phenol or 2,4,6-trichlorophenol have been replaced by new ones involving hydroquinone chlorination. These processes allow the preparation of chlorarul of higher purity, avoiding traces of pentachlorophenol. Different types of chlorination conditions have been disclosed. The reaction can be performed according to the following stoichiometry, operating with chlorine in aqueous acetic acid (86,87), biphasic medium (88), or in the presence of surfactants (89). 

The effluent from the reactor is a slurry of terephthaUc acid because it dissolves to a limited extent in almost all solvents, including the acetic acid—water solvent used here. This slurry passes through a surge vessel that operates at a lower pressure than the reactor. More terephthaUc acid crystallizes and the slurry is then ready to be processed at close to atmospheric conditions. The terephthaUc acid crystals are recovered by filtration, washed, dried, and conveyed to storage, from which they are in turn fed to the purification step. 

The original catalysts for this process were iodide-promoted cobalt catalysts, but high temperatures and high pressures (493 K and 48 MPa) were required to achieve yields of up to 60% (34,35). In contrast, the iodide-promoted, homogeneous rhodium catalyst operates at 448—468 K and pressures of 3 MPa. These conditions dramatically lower the specifications for pressure vessels. Yields of 99% acetic acid based on methanol are readily attained (see Acetic acid Catalysis). 

The transformed variables describe the system composition with or without reaction and sum to unity as do Xi and yi. The condition for azeotropy becomes X, = Y,. Barbosa and Doherty have shown that phase and distillation diagrams constructed using the transformed composition coordinates have the same properties as phase and distillation region diagrams for nonreactive systems and similarly can be used to assist in design feasibility and operability studies [Chem Eng Sci, 43, 529, 1523, and 2377 (1988a,b,c)]. A residue curve map in transformed coordinates for the reactive system methanol-acetic acid-methyl acetate-water is shown in Fig. 13-76. Note that the nonreactive azeotrope between water and methyl acetate has disappeared, while the methyl acetate-methanol azeotrope remains intact. Only... 

TABLE 11.2 Chemical Yields in Acetic Acid, Acetaldehyde, and CO2 for Pt/C and Pt-Sn (9 1)/C Catalysts during Ethanol Electro-oxidation under DEFC Operating Conditions at 80 "C for 4 Honrs ... 

After extracting fluthiacet-methyl from the soil extract with n-hexane, pass the residual aqueous layer through a dual cartridge of Sep-Pak Plus NH2 and Sep-Pak Plus C18 to adsorb the free form of fluthiacet-methyl on Sep-Pak Plus Gig. Remove the Sep-Pak Plus C18, wash it with 0.5% acetic acid and acetonitrile-water-acetic acid (20 80 0.5, v/v/v), elute with acetonitrile-water-acetic acid (50 50 0.5, v/v/v) and quantify the free form by HPLC. The operating conditions for HPLC are the same as those for fluthiacet-methyl, except that the mobile phase is acetonitrile-water-acetic acid (50 50 0.5, v/v/v) (retention time 8.8 min). 

Effect of Operating Conditions. Yield data, summarized in Figures 1 and 2, point to acetic acid homologation activity being sensitive to at least four operating variables, viz. ruthenium and methyl iodide concentrations, syngas composition and operating pressure. 

Figure 1. Acetic acid homologation (%) acetic acid, propionic acid, (A) butyric acids, and (V) valeric acids A, effect of Ru (operating conditions acetic acid, 417 mmol Mel, 20 mmol 220°C 476 atm constant pressure CO/H2 = 1/1) B, effect of Mel (operating conditions acidic acid, 417 mmol Ru(IV) oxide, 2.0 mmol 220°C 476 atm constant pressure CO/Ht = 1/1)...

Unlike SRE, the POE reaction for H2 production has been reported so far only by a few research groups.101104-108 While Wang et al. os and Mattos et r//.104-106 have studied the partial oxidation of ethanol to H2 and C02 (eqn (18)) at lower temperatures, between 300 and 400 °C using an 02/EtOH molar ratio up to 2, Wanat et al.101 have focused on the production of syngas (eqn (19)) over Rh/Ce02-monolith catalyst in a catalytic wall reactor in millisecond contact time at 800 °C. Depending on the nature of metal catalyst used and the reaction operating conditions employed, undesirable byproducts such as CH4, acetaldehyde, acetic acid, etc. have been observed. References known for the partial oxidation of ethanol in the open literature are summarized in Table 6. 

As shown in Fig. 9, the size of the region within which a complete conversion and separation occurs depends on the feed ratio. However, in all cases the existence of such a region was confirmed. A feed ratio of 0/100 (acetic acid/ethanol) actually represents a limiting case where no reaction occurs (identical to a non-reactive SMB). Since obviously there are many operating conditions where complete conversion and separation is achieved, other criteria should be introduced... 

Monsanto developed the rhodium-catalysed process for the carbonylation of methanol to produce acetic acid in the late sixties. It is a large-scale operation employing a rhodium/iodide catalyst converting methanol and carbon monoxide into acetic acid. At standard conditions the reaction is thermodynamically allowed,... 

Conversion rates as high as 99% are not encountered very often in the petrochemical industry. That coupled with relatively mild operating conditions, made this route, the economic favorite since it was introduced. About 75% of the world s acetic acid production comes from the methanol route. 

Table 1.2 Chemical yields in acetaldehyde, acetic acid and CO2 for the electro-oxidation of ethanol at Pt/C, Pt-Sn (90 10)/C and Pt-Sn-Ru (86 10 4)/C catalysts under DEFC operating conditions at 80 °C for 4 h.

High cell densities are not only a prerequisite for high productivity additionally an effective on-line control and modeling of the bioprocesses is necessary. For industrial applications, optical measurement methods are more attractive because they are non-invasive and more robust. The potential of the BioView sensor for on-line bioprocess monitoring and control was tested. For high-cell-density cultivation of Escherichia coli, maintaining aerobic conditions and removal of inhibitory by-products are essential. Acetic acid is known to be one of the critical metabolites. Information about changes in the cell metabolism and the time of important process operations is accessible on-line for optimization... 

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