Liquid recycle process

Figure 2.2. Block Flow Diagram for a Liquid Recycle Process...

In this example, we will consider asymmetric hydroformylation to give an aldehyde intermediate with a high ee. Gas Recycle is out of the question because of the low volatility of the product. Vaporization in a Liquid Recycle process is theoretically possible, but impractical if we wish to maintain the high enantioselectivity of the product. 

Later, the efficiency of the gas recycle process was improved by a switchover to the liquid recycle process, to which most plants have been converted in the meantime. Catalyst solution and aldehyde products leave the reactor as liquid and are... 

Table 11. UCC liquid recycle process typical data [204].

I Based on partiid liquid recycle process. Total liquid recycle process has just been developed. 

Type II Liquid recycle process/use of distillative separation... 

In the liquid recycle process product separation from the catalyst solution takes place outside of the reactor and independently of reaction conditions (Frohning et al, 2002). Figure 6.14.3 shows the process scheme. 

An important advantage of the liquid recycle process over the gas recycle process is that the product can be removed from the catalyst solution using vaporization parameters independent of the reaction parameters. This additional degree of... 

Figure 6.14.3 Schematic view of a liquid recycling process for propylene hydroformylation.

Cas reqrcle process Liquid recycle process Ruhrchemie/Rhone-Poulenc process... 

The reaction occurs in a liquid-phase process at approximately 400°C using ZnO or CdO catalysts. Terephthalic acid is obtained from an acid treatment the potassium salt is recycled. ° ... 

In some processes, a component may be recycled around two or more units in a closed loop. For example, the solvent in an absorption or liquid extraction process will normally be recovered by distillation and recycled. In this situation it will be necessary to introduce the solvent as a pseudo fresh-feed and the to remove it from the recycle loop by introducing a dummy stream divider, purging one stream. 

In Liquid Recycle, the conditions for the reaction are decoupled from those for the separation system. [10] Distillation is a widely practiced and well-understood technology, so it is generally the first consideration for any homogeneous catalytic process. A typical Liquid Recycle system is shown in Figure 2.2. 

Induced Phase Separation would work technically, but would be uneconomic relative to Liquid Recycle because of additional unit processes and increased energy requirements. 

Entrainment Separators. In any process in which the product is volatilized, including both Gas Recycle and Liquid Recycle, ppm or ppb levels of metal catalyst may be entrained in the vapors leaving the separation system. Entrainment separators (Figure 2.9) are often included to recover the metal. Vaporous product effluent from a gas recycle reactor may be sent to a separator where it is passed through a demisting pad to return some aldehyde and condensation product and particularly to prevent potential carryover of catalyst. [6]... 

Recently, Dupont and coworkers described the use of room-temperature imi-dazolium ionic liquids for the formation and stabilization of transition-metal nanoparticles. The potential interest in the use of ionic liquids is to promote a bi-phasic organic-organic catalytic system for a recycling process. The mixture forms a two-phase system consisting of a lower phase which contains the nanocatalyst in the ionic liquid, and an upper phase which contains the organic products. Rhodium and iridium [105], platinum [73] or ruthenium [74] nanoparticles were prepared from various salts or organometallic precursors in dry 1-bu-tyl-3-methylimidazolium hexafluorophosphate (BMI PF6) ionic liquid under hydrogen pressure (4 bar) at 75 °C. Nanoparticles with a mean diameter of 2-3 nm... 

Recent efforts have concentrated on the immobilization of these materials onto both organic polymers(11) and metal oxides(12) to simplify, by filtration, the separation, recovery and recycle process. These supported catalysts now function in a triphasic environment in either a liquid-solid-liquid or solid-liquid-solid reaction mixture. In this case, the catalyst must transfer the anion from the surface of the crystal lattice to the liquid phase. Here adsorption phenomena often significantly affect the reaction rate(13). 

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