Downstream processing extraction

Downstream Processing. In addition to extraction, various downstream operations are often carried out on the BTX product to produce products in proportions to fit the market demand. A typical aromatics processing scheme is shown in Eigure 8 in which ben2ene, xylene, and o-xylene are the products. 

After the cmde BTX is formed, by reforming in this case, a heart cut is sent to extraction. Actually, the xylenes and heavier components are often sent to downstream processes without extraction. The toluene produced is converted to ben2ene, a more valuable petrochemical, by mnning it through a hydrodealkylation unit. This catalytic unit operates at 540—810°C with an excess of hydrogen. Another option is to disproportionate toluene or toluene plus aromatics to a mixture of ben2ene and xylenes using a process such as UOP s Tatoray or Mobil s Selective Toluene Disproportionation Process (STDP) (36). 

FIG. 22-86 Process scheme for protein extraction in aqueous two-phase systems for the downstream processing of intracellular proteins, incorporating PEG and salt recycling. RepHnted from Kelly and Hatton in Stephanopoulos (ed), op. cit. adapted from Qre-oe and Kula, op. cit.]... 

When ionic liquids are used as replacements for organic solvents in processes with nonvolatile products, downstream processing may become complicated. This may apply to many biotransformations in which the better selectivity of the biocatalyst is used to transform more complex molecules. In such cases, product isolation can be achieved by, for example, extraction with supercritical CO2 [50]. Recently, membrane processes such as pervaporation and nanofiltration have been used. The use of pervaporation for less volatile compounds such as phenylethanol has been reported by Crespo and co-workers [51]. We have developed a separation process based on nanofiltration [52, 53] which is especially well suited for isolation of nonvolatile compounds such as carbohydrates or charged compounds. It may also be used for easy recovery and/or purification of ionic liquids. 

Sweetening of the FCC gasoline is usually sufficient to meet its sulfur specifications. However, in areas where reformulated gasoline is marketed, sulfur specifications in the gasoline may require more treatment. The mercaptans in the LPG need to be extracted to protect the downstream processes, such as alkylation. Sulfur increases acid consumption and produces undesirable by-products. 

Product extraction Effluent and waste disposal Medium preparation Seed vessel Purification Cell free supernatant Cell biomass Production bioreactor Downstream processing Medium sterilisation Primary culture Upstream processing... 

After fermentation, subsequent midstream to downstream processes such as cell disruption, centrifugation, extraction and drying will be carried on for product recovery. Fig. 9 shows a white sheet of PHB obtained from fermentation of sweet sorghum juice (SSJ) by Bacillus aryahhattai. 

The same resin was used for the purification via downstream processing of carminic acid, the natural colorant extracted from cochineal. By a direct adsorption method, a crude extract was applied on the polymeric bed gel and the adsorption kinetics studied using elution with hydrochloric acid and ethanol. The desorbed pure carminic acid concentrated under vacuum yielded a final product that complied with Codex Alimentarius requirements and FAO/OMS norms. 

Figure 4.14 Chemical adducts for by-product removal synthesis of isopropyl-cis-Ag-hexadecanoate from isopropylpalmitate applying a repetitive batch process using a sequence of stirred-tank reactor, extraction module, filtration step and chromatographic downstream processing...

Figure 4.21 Multiphase membrane reactor synthesis of ibuprofen from ibuprofen methoxyethyl ester applying a multiphase membrane reactor in batch mode followed by extraction and distillation for downstream processing...

It is useful to subdivide the downstream processing of recombinant proteins into a few key stages, often referred to as initial processing of the source material and extraction (if necessary), capture, intermediate purification and polishing. These can then be further split into unit operations. In each of these stages, predefined goals have to be achieved, so a well-defined purification protocol will sequentially utilize as... 

Reverse Micellar Extraction for Downstream Processing of Proteins/Enzymes... 

Keywords. Downstream processing. Reverse micelles, Protein/enzyme extraction. Modeling, Recent developments... 

---