Processes Sorbex technology

Citric Acid Separation. Citric acid [77-92-9] and other organic acids can be recovered from fermentation broths usiag the UOP Sorbex technology (90—92). The conventional means of recovering citric acid is by a lime and sulfuric acid process ia which the citric acid is first precipitated as a calcium salt and then reacidulated with sulfuric acid. However, this process generates significant by-products and thus can become iaefficient. 

Citric acid (Ruthven, 1997). In the separation of citric acid from fermentation liquors the Sorbex process can be used. In the conventional process neutralization is carried out with lime followed by acidification with sulphuric acid to produce calcium sulphate as waste. The Sorbex technology avoids lime and sulphuric acid wastage and calcium sulphate disposal. 

The Parex, Toray Aromax and Axens Eluxyl processes are the three adsorptive liquid technologies for the separation and purification of p-xylene practiced on a large scale today. The MX Sorbex process is the only liquid adsorptive process for the separation and purification of m-xylene practiced on an industrial scale. We now consider a few other liquid adsorptive applications using Sorbex technology for aromatics separation that have commercial promise but have not found wide application. 

Expansion of Sorbex technology to the production of m-xylene shows how the process concept can be used for multiple applications in separations that cannot be performed by other means. One can expect that, as demand for new, difficult to separate aromatics increases, the simulated moving bed liquid adsorption processes can provide a means for production. 

There are three liquid-phase adsorption Sorbex technology-based separation processes for the production of olefins. The first two are the UOP C4 Olex and UOP Sorbutene processes and the third is the detergent Olex process(Cio i,5) [25, 26]. The three olefin separation processes share many similarities. The first similarity between the three olefin separation processes is that each one utilizes a proprietary adsorbent whose empirical formula is represented by Cation,([(A102)),(Si02)2] [27]. The cation type imparts the desired selectivity for the particular separation. This zeolite has a three-dimensional pore structure with pores running perpendicular to each other in the x, y and z planes [28]. The second similarity between the three olefin separation processes is the use of a mixed olefin/paraffin desorbent. The specifics of each desorbent composition are discussed in their corresponding sections. The third similarity is the fact that all three utilize the standard Sorbex bed allotment that enables them to achieve product purities in excess of 98%. The following sechons review each process in detail. 

Application The MaxEne process increases the ethylene yield from naphtha crackers by raising the concentration of normal paraffins (n-paraffins) in the naphtha-cracker feed. The MaxEne process is the newest application of UOP s Sorbex technology. The process uses adsorptive separation to separate C5-Cn naphtha into a rich n-paraffins stream and a stream depleted of n-paraffins. 

Application The MX Sorbex process recovers mefa-xylene (m-xylene) from mixed xylenes. UOP s innovative Sorbex technology uses adsorptive separation for highly efficient and selective recovery, at high purity, of molecular species that cannot be separated by conventional fractionation. 

Other versions of the sinwiated moving-bed process have been commercialized by Toray Industries. Inc. " and Mitsubishi Chemical Industries, Ltd." These processes vary from the Sorbex technology in detaib rather than in their basic concept. 

FIG. 16-45 UOP Sorbex process. (Reprinted with permission of John Wiley b Sons, Inc. Reference Gembicki, Oroskar, and Johnson, "Adsorption, Liquid Separationin Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed.,John Wiley b- Sons, Inc., New York, 1991.)... 

As documented in Chapter 5, zeolites are very powerful adsorbents used to separate many products from industrial process steams. In many cases, adsorption is the only separation tool when other conventional separation techniques such as distillation, extraction, membranes, crystallization and absorption are not applicable. For example, adsorption is the only process that can separate a mixture of C10-C14 olefins from a mixture of C10-C14 hydrocarbons. It has also been found that in certain processes, adsorption has many technological and economical advantages over conventional processes. This was seen, for example, when the separation of m-xylene from other Cg-aromatics by the HF-BF3 extraction process was replaced by adsorption using the UOP MX Sorbex process. Although zeolite separations have many advantages, there are some disadvantages such as complexity in the separation chemistry and the need to recover and recycle desorbents. 

The Parex and MX Sorbex processes are quite similar with regard to the adsorbent section mechanics so all of the discussion about the functional zones in the section for the Parex process applies to the MX Sorbex process also. The MX Sorbex process produces m-xylene at 99.5-99.8% purity at a recovery in excess of 95%. The major differences between the two technologies are the choice of adsorbent and desorbent... 

Application The Molex process recovers normal C10-C13 paraffins from kerosine using UOP s innovative Sorbex adsorptive separation technology. 

This process, applied to the treatment of C4 cuts and more specifically to the manufacture of 1-butene, is one the many variants of adsorption technology on molecular sieves called Sorbex and developed by UOF, to separate paraffms (Molex). olefins (Olex)... 

The SMB technology was developed by UOP and its major field of application is in the area of binary separations. For example, SMB has been used in the chemical industry for several separations known as SORBEX processes [1-3], which include, among others, the PAREX process for p-xylene separation from a Cs aromatic fraction [4], the OLEX process for the separation of olefins from paraffins, the SAREX process to separate fructose from glucose [4] and the MOLEX process [5]. Simulated moving bed is being used particularly for separation of enantiomers from racemic mixtures or from the products of enantioselective synthesis [6,7]. It has been used for the production of fine chemicals, and petrochemical intermediates, such as Cg-hydrocarbons [8], food chemistry such as fatty acids [2], or certain sugars from carbohydrate mixtures [8] and protein desalination [9]. 

Adsorption technology as provided by the SORBEX processes can separate complex feed mixtures by class or by specific isomer. Unlike conventional processes which only rely on differences in physical properties, adsorption can be customized to achieve a precise separation. 

Needless to emphasize that UOP s Cresex process—an adaptation and extension of its generalized Sorbex processes—provides a unique opportunity for separation of m-p-cresols into pure p-cresol (99%) and pure m-cresol (99%). Quite surprisingly UOP has till now licensed cresex technology... 

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