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Process catalyst separation

Recent advances in Eischer-Tropsch technology at Sasol include the demonstration of the slurry-bed Eischer-Tropsch process and the new generation Sasol Advanced Synthol (SAS) Reactor, which is a classical fluidized-bed reactor design. The slurry-bed reactor is considered a superior alternative to the Arge tubular fixed-bed reactor. Commercial implementation of a slurry-bed design requires development of efficient catalyst separation techniques. Sasol has developed proprietary technology that provides satisfactory separation of wax and soHd catalyst, and a commercial-scale reactor is being commissioned in the first half of 1993. [Pg.164]

Because of its volatility, the cobalt catalyst codistills with the product aldehyde necessitating a separate catalyst separation step known as decobalting. This is typically done by contacting the product stream with an aqueous carboxyhc acid, eg, acetic acid, subsequently separating the aqueous cobalt carboxylate, and returning the cobalt to the process as active catalyst precursor (2). Alternatively, the aldehyde product stream may be decobalted by contacting it with aqueous caustic soda which converts the catalyst into the water-soluble Co(CO). This stream is decanted from the product, acidified, and recycled as active HCo(CO)4. [Pg.466]

In 1974, Monsanto brought on-stream an improved Hquid-phase AIQ. alkylation process that significantly reduced the AIQ. catalyst used by operating the reactor at a higher temperature (42—44). In this process, the separate heavy catalyst—complex phase previously mentioned was eliminated. Eliminating the catalyst—complex phase increases selectivities and overall yields in addition to lessening the problem of waste catalyst disposal. The ethylben2ene yields exceed 98%. [Pg.48]

Figure 8-5. The Hoechst AG and Rhone Poulenc process for producing butyraldehydes from propene (1) reactor, (2) catalyst separation, (3) stripper (using fresh syngas to strip unreacted propylene to recycle), (4) distillation. Figure 8-5. The Hoechst AG and Rhone Poulenc process for producing butyraldehydes from propene (1) reactor, (2) catalyst separation, (3) stripper (using fresh syngas to strip unreacted propylene to recycle), (4) distillation.
Fuel cells essentially reverse the electrolytic process. Two separated platinum electrodes immersed in an electrolyte generate a voltage when hydrogen is passed over one and oxygen over the other (forming H30+ and OH-, respectively). Ruthenium complexes are used as catalysts for the electrolytic breakdown of water using solar energy (section 1.8.1). [Pg.174]

The general picture of the relative merits of homogeneous and heterogeneous processes has not yet emerged clearly. The homogeneous catalyst system may offer advantages in chemical efficiency but lead to difficulties of catalyst separation and recovery, or catalysts may tend to plate out in the reactor due to slight instability. Materials of construction may have to be different for the two rival plants. All these factors will have to be considered in an economic assessment and detailed studies made of the complete process networks in both cases. [Pg.231]

Cobalt catalysts such as HCo(CO)4 are widely used for hydroformyla-tion of higher alkenes, despite the higher temperatures and pressures required. The main reason for this is that these catalysts are also efficient alkene isomerization catalysts, allowing a mix of internal and terminal alkenes to be used in the process. Catalyst recovery is more of a problem here, involving production of some waste and adding significantly to the complexity of the process. A common recovery method involves treating the catalyst with aqueous base to make it water soluble, followed by separation and subsequent treatment with acid to recover active catalyst (4.3). [Pg.112]

In the sixties of past century, a few patents issued to Bergbau Chemie [5,48,49] and to Mobil Oil [50-52], respectively described the use of CFPs as supports for catalytically active metal nanoclusters and as carriers for heterogenized metal complexes of catalytic relevance. For the latter catalysts the term hybrid phase catalysts later came into use [53,54], At that time coordination chemistry and organo-transition metal chemistry were in full development. Homogeneous transition metal catalysis was expected to grow in industrial relevance [54], but catalyst separation was generally a major problem for continuous processing. That is why the concept of hybrid catalysis became very popular in a short time [55]. [Pg.208]

As mentioned earlier, a major cause of high costs in fine chemicals manufacturing is the complexity of the processes. Hence, the key to more economical processes is reduction of the number of unit operations by judicious process integration. This pertains to the successful integration of, for example, chemical and biocatalytic steps, or of reaction steps with (catalyst) separations. A recurring problem in the batch-wise production of fine chemicals is the (perceived) necessity for solvent switches from one reaction step to another or from the reaction to the product separation. Process simplification, e.g. by integration of reaction and separation steps into a single unit operation, will provide obvious economic and environmental benefits. Examples include catalytic distillation, and the use of (catalytic) membranes to facilitate separation of products from catalysts. [Pg.54]

The second important piece in the process development is the separation scheme. Several methods were suggested, such as decanting, water extraction or fractional distillation, use of hydrocyclones, hydrophobic membrane filters, etc. In the early work at EBC, many of its patents refer to facilitating catalyst separation via immobilization, although no mention is given on how activity was impacted by that immobilization. Furthermore, there were no details on how immobilization was achieved and which were the preferred means and techniques. [Pg.148]

In this book, we report on the state of the art of methods for catalyst separation recovery and recycling, not just describing the chemistry, but also discussing the process design that would be required to put the processes into practice. [Pg.7]

Despite the very attractive properties of the rhodium-based system, no commercial plants used it because the low stability of the catalyst meant that the catalyst separation problem prevented commercialisation. Very recently, this situation has changed with the introduction of rhodium-based plant by Sasol in South Africa which uses technology developed by Kvaemer Process Technology (now Davy Process Technology). This batch continuous plant produces medium-long chain aldehydes and the separation is carriedoutbylow pressure distillation [16-18]... [Pg.8]

Figure 5.3. Basic flow-sheets of a) a conventional, homogeneously catalyzed process and b) an aqueous-biphasically, homogeneous catalytic process. 1, Reactor 2 Separators) 3, Catalyst separator 4, Make-up 5, Further purification and processing, Gas recycles) 7, Catalyst recycle 8, Reactant feed 9, Withdrawal of high... Figure 5.3. Basic flow-sheets of a) a conventional, homogeneously catalyzed process and b) an aqueous-biphasically, homogeneous catalytic process. 1, Reactor 2 Separators) 3, Catalyst separator 4, Make-up 5, Further purification and processing, Gas recycles) 7, Catalyst recycle 8, Reactant feed 9, Withdrawal of high...
Advantageously, SAPC as a technique with immobilized catalysts does not need devices for catalyst separation and recycling, since the reactions can in principle be carried out using standard flow reactors commonly used in heterogeneous catalysis. On the other hand, the presumed processes for the work-up of the constituents of the catalyst, the ligand (and - may be - the support) will be demanding and expensive, too. [Pg.122]

A wide variety of new approaches to the problem of product separation in homogeneous catalysis has been discussed in the preceding chapters. Few of the new approaches has so far been commercialised, with the exceptions of a the use of aqueous biphasic systems for propene hydroformylation (Chapter 5) and the use of a phosphonium based ionic liquid for the Lewis acid catalysed isomerisation of butadiene monoxide to dihydrofuran (see Equation 9.1). This process has been operated by Eastman for the last 8 years without any loss or replenishment of ionic liquid [1], It has the advantage that the product is sufficiently volatile to be distilled from the reactor at the reaction temperature so the process can be run continuously with built in product catalyst separation. Production of lower volatility products by such a process would be more problematic. A side reaction leads to the conversion of butadiene oxide to high molecular weight oligomers. The ionic liquid has been designed to facilitate their separation from the catalyst (see Section 9.7)... [Pg.237]

D.J. Cole-Hamilton and R.P. Tooze (eds) Catalyst Separation, Recovery and Recycling. Chemistry and Process Design. 2006 ISBN 1-4020-4086-5... [Pg.250]

A Continuous Process for Separation of Wax from Iron Nano-Catalyst Particles by Using Cross-Flow Filtration... [Pg.269]

Total Isomerization Also called TIP. An integrated process which combines light paraffin isomerization, using a zeolite catalyst, with the IsoSiv process, which separates the unconverted normal paraffins so that they can be returned to the reactor. Developed by Union Carbide Corporation and now licensed by UOP. The first plant was operated in Japan in 1975 by 1992, more than 25 units had been licensed. [Pg.272]

In addition, many other aspects must be considered when developing a catalytic reaction for industrial use these include catalyst separation, stability and poisoning, handling problems, space-time yield, process sensitivity and robustness, toxicity of metals and reagent, and safety aspects, as well as the need for high-pressure equipment. [Pg.1282]

The use of alternative solvents in hydrogenation and hydroformylation reactions has developed at an incredible rate over the last few years. Many elegant systems have been designed which offer cleaner alternatives to those carried out in conventional organic solvents. Apart from the attractiveness of the separation process, catalyst lifetimes can be extended which represents another major advantage. In some cases, conventional organic solvents are completely removed from the system. [Pg.179]

Phase transfer catalysis (1,2) has become in recent years a widely used, well-established synthetic technique applied with advantage to a multitude of organic transformations. In addition to a steadily increasing number of reports in the primary literature, there are several reviews (3-6), comprehensive monographs (7-10) and an ACS Audio Course (1 ) which describe the phase transfer process and which provide extensive compilations of phase transfer agents and reaction types. While the list of applications and in many cases the synthetic results are impressive, phase transfer catalysts (PTCs) suffer some of the same disadvantages as more conventional hetero-and homogeneous catalysts — separation and... [Pg.169]


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See also in sourсe #XX -- [ Pg.119 ]




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