Reactive separations

Residuum oil supercritical extraction-petroleum deasphalting Polymer fractionation Edible oils fractionation Analytical SGF extraction and chromatography Reactive separations... 

A process lean stream and an external MSA are considered for removing H2S. The process lean stream, S1, is a caustic soda solution which can be used as a solvent for the reactive separation of H2S. An added bonus for using the process MSA is the conversion of a portion of the absorbed H2S into Na2S, which is needed for white-liquor makeup. In other words, H2S pollutant is converted into a valuable chemical which is needed in the process. The external MSA, S2, is a polym ic adsorbent. The data for the candidate MSAs are given in Table 8.2. The equilibrium... 

Stankiewicz, A. I., Reactive separations for process intensification an industrial perspective, Chem. Eng. Proc. 42 (2003) 137-144. 

Reactive Separations Reactions may be integrated with SCF separation processes to achieve a large degree of control for producing a highly purified product. Reaction products may be recovered by... 

Gas-expanded liquids (GXLs) are emerging solvents for environmentally benign reactive separation (Eckert et al., op. cit.). GXLs, obtained by mixing supercritical CO2 with normal liquids, show intermediate properties between normal liquids and SCFs both in solvation power and in transport properties and these properties are highly tunable by simple pressure variations. Applications include chemical reactions with improved transport, catalyst recycling, and product separation. 

Industrial processes for recycling have been developed which take advantage of reactively separating hydrolysable polymers from nonhydrolysable waste plastics [651]. 

Our "superheated liquid-film concept" stands on the thermodynamic basis of (1) equilibrium shifts due to reactive separation under boiling and refluxing conditions and (2) irreversible processes of heat flows through the catalyst layer as well as bubble formation from the catalyst surface. 

Melt-state testing, of polymers, 19 575 Melt-to-mold thermoforming, 18 49 Melt viscosities (MVs), 21 712-714 of ethylene oxide polymers, 10 680 of FEP resin, 18 306, 308 Membrane-based reactive separation processes, 15 848... 

Kulprathipanja, S. (2002) Reactive Separation Process, Taylor Francis, New York, USA. 

R. Krishna, Reactive Separation a New Paradigm in an Old Bottle, Report from Chemical Engineering department, University of Amsterdam, 1999. 

Reactive absorption is probably the most widely applied type of a reactive separation process. It is used for production purposes in a number of classical bulk-chemical technologies, such as nitric or sulfuric acid. It is also often employed in gas purification processes, e.g., to remove carbon dioxide or hydrogen sulfide. Other interesting areas of application include olefin/paraffin separations, where reactive absorption with reversible chemical complexation appears to be a promising alternative to the cryogenic distillation (62). 

One speaks in those cases about reactive separations or separative reactors. The industrially important reactive separations include ... 

Reactive distillation Membrane-based reactive separations Reactive adsorption Reactive absorption Reactive extraction Reactive crystallization... 

Despite many ongoing research activities in the field and a number of successful commercializations, there still exist numerous technical and nontechnical barriers that hinder a wider introduction of reactive and hybrid separations into industrial practice. Two workshops held in 1998 by the Center for Waste Reduction Technologies of AIChE (305) identified some of the barriers for reactive separations and divided them into three categories ... 

Tlatlik S, Schembecker G. Process synthesis for reactive separations. In Proceedings of ARS-1, Advances in Reactive Separations 1, University of Dortmund, Germany, October 12, 2000 1-10. 

The most important examples of reactive separation processes (RSPs) are reactive distillation (RD), reactive absorption (RA), and reactive extraction (RE). In RD, reaction and distillation take place within the same zone of a distillation column. Reactants are converted to products, with simultaneous separation of the products and recycling of unused reactants. The RD process can be efficient in both size and cost of capital equipment and in energy used to achieve a complete conversion of reactants. Since reactor costs are often less than 10% of the capital investment, the combination of a relatively cheap reactor with a distillation column offers great potential for overall savings. Among suitable RD processes are etherifications, nitrations, esterifications, transesterifications, condensations, and alcylations (2). 

Figure 1 Reactive separation units as multifunctional reactors. (Inspired by Ref. 4.)...

On the other hand, RD, RA, and RE have a number of specific features that should be considered with care and described by different approaches. Before going into detail, it is worthy to note that the operating window of reactive separations may be somewhat limited, since these operations are feasible only if they allow for both separation and reaction within the same range of temperature and pressure and, on the other hand, for the safe operation from the constructional point of view (Figure 2). 

Figure 2 Feasibility of reactive separation, depending on mechanical design, chemical reaction, and separation performance.

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