Two-phase technology

Because the thermal separation of products has been substituted by a liquid-liquid separation, the two phase technology should be best suited for hydroformylation of longer chain olefins. But with rising chain length of the olefins the solubility in the aqueous catalyst phase drops dramatically and as a consequence the reaction rate. Only the hydroformylation of 1-butene proceeds with bearable space-time yield. This is applied on a small scale for production of valeraldehyde starting from raffinate II. Because the sulfonated triphenylphosphane/rhodium catalyst exhibits only slow isomerization and virtually no hydroformylation of internal double bonds, only 1-butene is converted. The remaining raffinate III, with some unconverted 1-butene and the unconverted 2-butene, is used in a subsequent hydroformy-lation/hydrogenation for production of technical amylalcohol, a mixture of linear and branched C5-alcohols. 

This particular combination of a one-phase and a two-phase technology is possible because of high Difasol efficiency on the diluted feed recovered from the Dimersol reactor. This arrangement is suitable either for grass-roots units or for upgrading of existing Dimersol-X units. It considerably reduces the overall unit volume compared to existing (up to four-reactor) Dimersol-X units. It also induces lower catalyst consumption, i.e., lower catalyst and disposal costs (Table 4). 

A recent breakthrough has been the use of two-phase technology, commercialized in the Ruhrchemie/Rhone Poulenc process, which uses a new water-soluble rhodium complex with polar SOsNa groups on the phenyl rings of the phosphine (TPPTS) [1]. 

The major advantage of applying two-phase technology is the easy separation of catalyst phase and product phase. Due to the low solubility of butanal, pentanal, etc. in water and vice versa the separation of the reaction and product layer causes no problem in general, phase separation occurs fast and complete. Propanal, however, derived from the hydroformylation of ethylene, bears a significant miscibility with water. This causes two problems ... 

While advanced two-phase technology such as capillary pumped loops and loop heat pipes offer major advantages over traditional thermal control technology, it is clear that this technology alone will not meet the needs of all future scientific spacecraft... . 

Hence, for deep desulfurization, a two-phase reactor (oil externally pre-saturated with H2 and solid catalyst) could be an alternative to the trickle bed. The H2-recycle is then redundant, and scale-up problems do not occur. In addition, the two-phase technology utilizes the maximum intrinsic chemical reaction rate as pore diffusion does not play a role in the slow desulfurization of refractory compounds left in predesulfurized feedstocks. For a trickle bed this rate is an upper limit, which caimot, or only hardly, be reached with regard to improper gas-liquid distribution and/or wetting of the catalyst. A laboratory-scale tricHe-bed and two-phase reactor with pre-saturation are compared in Figure 6.8.10 for a model oil. 

Liquid-Phase Oxidation of Acrolein. As discussed before, the most attractive process for the manufacture of acrylates is based on the two-stage, vapor-phase oxidation of propylene. The second stage involves the oxidation of acrolein. Considerable art on the Hquid-phase oxidation of acrolein (17) is available, but this route caimot compete with the vapor-phase technology. 

A large number of hard polymer/elastomer combinations made by the last technique have been investigated (30). In some cases, the components are technologically compatibilized by use of a grafting reaction, but usually a fine dispersion of the two phases is formed that is sufficient to give the product the properties of a thermoplastic elastomer. 

The new Clean Air Act will result in a permanent 10 million ton reduction in sulfur dioxide (SOj) emissions from 1980 levels. To achieve this, EPA will allocate allowances of one ton of sulfur dioxide in two phases, The first phase, effective January 1, 1995, requires 110 powerplants to reduce their emissions to a level equivalent to the product of an emissions rate = (2,5 lbs of S02/mm Btu) x (the average mm Btu of their 1985-1987 fuel use). Plants that use certain control technologies to meet their Phase 1 reduction requirements may receive a two year extension of compliance until 1997. The new law also allows for a special allocation of 200,000 annual allowances per year each of the 5 years of Phase 1 to powerplants in Illinois, Indiana and Ohio. 

Reprinted from M. Lampinen, Calculation Methods for Determining the Pressure Loss of Two-Phase Pipe Flow and Ejectors in Pneumatic Conveying Systems, Acta Polytechnica Scandinavica, Mechanical Engineering Series No. 99, published by the Finnish Academy of Technology, Helsinki, 1991. 

Proteins (BSA or ovomucoid, OVM) have also been successful in the preparative resolution of enantiomers by liquid-liquid extraction, either between aqueous and lipophilic phases [181] or in aqueous two-phase systems (ATPS) [123, 180]. The resolution of d,l-kynurenine [180] and ofloxacin and carvediol [123] were performed using a countercurrent extraction process with eight separatory funnels. The significant number of stages needed for these complete resolutions in the mentioned references and others [123, 180, 189], can be overcome with more efficient techniques. Thus, the resolution of d,l-kynurenine performed by Sellergren et al. in 1988 by extraction experiments was improved with CCC technologies 10 years later [128]. 

Ionic liquids have already been demonstrated to be effective membrane materials for gas separation when supported within a porous polymer support. However, supported ionic liquid membranes offer another versatile approach by which to perform two-phase catalysis. This technology combines some of the advantages of the ionic liquid as a catalyst solvent with the ruggedness of the ionic liquid-polymer gels. Transition metal complexes based on palladium or rhodium have been incorporated into gas-permeable polymer gels composed of [BMIM][PFg] and poly(vinyli-dene fluoride)-hexafluoropropylene copolymer and have been used to investigate the hydrogenation of propene [21]. 

Figure 2.5 Possible technological solutions to bioprocess problems a) Fed-batch culture b) Continuous product removal (eg dialysis, vacuum fermentation, solvent extraction, ion exchange etc) c) Two-phase system combined with extractive fermentation (liquid-impelled loop reactor) d) Continuous culture, internal multi-stage reactor e) Continuous culture, dual-stream multi-stage reactor f) Continuous culture with biomass feedback (cell recycling). (See text for further details).

After cooling of the aqueous mixture to 5-10°C an upper viscous phase is separated, which contains 45-47% alkanesulfonates and 1.0-1.3% sodium chloride, while the lower phase is a 7-8% brine with a small quantity of alkane-monosulfonates but 1.5-2.0 wt % di- and polysulfonates. The hydrotropically dissolved alkanes (neutral oil) are found entirely in the upper phase. Because of the small density differences, the separation of the two phases needs 15-20 h. The lower phase can be separated by membrane technology [13]. 

Ozawa M, Akagawea K, Sakaguchi T (1989) Flow instabilities in paraUel-channel flow systems of gas-liquid two-phase mixtures. Int 1 Multiphase Flow 15 639-657 Peles YP (1999) VLSI chip cooling by boiling-two-phase flow in micro-channels. Dissertation, Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa Peles YP, Yarin LP, Hetsroni G (2001) Steady and unsteady flow in heated capUlary. Int J Multiphase Flow 22 577-598... 

This paper demonstrates the technical feasibility of a plastics energy recovery plant using circulating fluidised bed technology from Ahlstrom of Finland. Full details are given of a two-phase test run conducted at Ahlstrom s pilot plant in Karhula, in order to obtain information on the process behaviour when combusting different types of plastics waste. Results are presented and conclusions drawn. 

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