Acetic acid recovery

Commercial production of acetic acid has been revolutionized in the decade 1978—1988. Butane—naphtha Hquid-phase catalytic oxidation has declined precipitously as methanol [67-56-1] or methyl acetate [79-20-9] carbonylation has become the technology of choice in the world market. By-product acetic acid recovery in other hydrocarbon oxidations, eg, in xylene oxidation to terephthaUc acid and propylene conversion to acryflc acid, has also grown. Production from synthesis gas is increasing and the development of alternative raw materials is under serious consideration following widespread dislocations in the cost of raw material (see Chemurgy). 

The bottoms from the solvent recovery (or a2eotropic dehydration column) are fed to the foremns column where acetic acid, some acryflc acid, and final traces of water are removed overhead. The overhead mixture is sent to an acetic acid purification column where a technical grade of acetic acid suitable for ester manufacture is recovered as a by-product. The bottoms from the acetic acid recovery column are recycled to the reflux to the foremns column. The bottoms from the foremns column are fed to the product column where the glacial acryflc acid of commerce is taken overhead. Bottoms from the product column are stripped to recover acryflc acid values and the high boilers are burned. The principal losses of acryflc acid in this process are to the aqueous raffinate and to the aqueous layer from the dehydration column and to dimeri2ation of acryflc acid to 3-acryloxypropionic acid. If necessary, the product column bottoms stripper may include provision for a short-contact-time cracker to crack this dimer back to acryflc acid (60). 

The monosaccharides and acetic acid recoveries obtained on enzymatic posthydrolysis are also provided in Table 1. The concentrations of formic and levulinic acids, HMF, and furfural concentrations were also determined, but in all cases, they remained unchanged throughout the enzymatic process. The same trend was observed for the total phenolic content (data not shown). 

Enzyme Activity Levels Present in Reaction Mixture for Different Commercial Enzyme Preparations Used and Respective Monosaccharides and Acetic Acid Recoveries for Enzymatic Posthydrolysis of BSG OCLfl... 

CUT 2 - Maximise the amount of acetic acid recovery, thus leaving acetic anhydride as the final bottom product in the reboiler. 

The bottoms from the solvent recovery (or azeotropic dehydration column) are fed to the foreruns column where acetic acid, some acrylic acid, and final traces of water are removed overhead The overhead mixture is sent to an acetic acid purification column where a technical grade of acetic acid suitable for ester manufacture is recovered as a by-product. The bottoms from the acetic acid recovery column are recycled to the reflux to the foreruns column. 

Figure 52. Specific Steam Consumption of Acetic Acid Recovery Plants as based on Extraction with Ethyl Acetate.

Added acetic acid, ppm Theoretical content of acetic acid, % Found acetic acid, % Recovery rate, %... 

Solvent selection for acetic acid recovery Maximization of acetic acid recovery and process flexibility, and minimization of environmental impact based on lethal-dosage (LDa) and lethal-concentration (LC50) Constraint multiobjective programming (MOP) method Aspen Plus was employed to simulate the process, and uncertainty was also considered. The proposed MOP method is similar to the e-constraint method. Kim and Diwekar (2002)... 

Acetic acid recovery by batch distillation from aqueous waste mixtures in pharmaceutical industries Maximization of total profit and minimization of potential environmental impact. Parallel multiobjective steady-state GA(pMSGA) MSGA uses a new fimess-sharing function based on Euclidean distances from an individual, and produces evenly distributed Pareto-optimal solutions. Three different feed compositions were considered. Kim and Smifli (2004)... 

Reduce the acetic acid recovery/recycle/disposal Avoid toxic by-products... 

FIGURE 7.8-8 Acetic acid recovery by solvent extraction and azeotropic distillation. (From Ref, 22 with permission.)... 

Acetaldehyde Calcium acetate Carbon monoxide Methyl alcohol acetic acid recovery Isopropyl acetate Propyl acetate acetic anhydride mfg. 

Tetrahydrofuran Trihexylphosphine oxide extraction agent, acetic acid recovery Trioctylphosphine oxide extraction agent, actinide Aluminum nitrate nonahydrate extraction agent, animal/vegetable oils Methyl alcohol... 

Many investigations of die extraction of ethanrd fixmi water have postulated that a veiy high selectivity is needed to enrich the solvent-free extract to an ethanol contem near or above die binaty azeotrope with water. However, this degree of enrichmem is not necessary. The extraction step can be followed by an extractive-distillation dewatering step similar to die process shown fin acetic acid recovery in Fig. 15.2-3. 

Fig. 6-7, Acetic acid recovery by liquid-liquid extraction, simplified flow sheet. Representation according to [6.100].

The total batch time and the recoveries of the three products are pretty much the same with the wide 10°C mismatches of temperature upward or downward (101.73 or 81.73°C). Only when this setpoint is set to be too low at 71.73°C does the batch operation fail with the organic phase totally refluxed but still not able to reach the temperature setpoint. At this low temperature setpoint value causing total refluxing of the organic phase, Strategy A discussed in Section 13.3.2 should be implemented with two sequential steps in the batch sequence (aqueous product recovery step and followed by the entrainer-acetic acid recovery step). However, because our proposed procedure only allows for simultaneous recovery of the three products, the batch operation failed. 

Acetic Acid 72 267 131 G G - - tests for selection of material for an acetic acid recovery column for an acetaldehyde unit, 91 hrs. 

Dilute acetic acid recovery Indion 130 Saha and Mahajani (2000)... 

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