Regeneration efficiency

An adsorbent attracts molecules from the gas, the molecules become concentrated on the surface of the adsorbent, and are removed from the gas phase. Many process concepts have been developed to allow the efficient contact of feed gas mixtures with adsorbents to carry out desired separations and to allow efficient regeneration of the adsorbent for subsequent reuse. In nonregenerative appHcations, the adsorbent is used only once and is not regenerated. 

FIG. 17-24 Modem FCC unit configured for high-efficiency regeneration and extra catalyst cooling. (Reptinted with peimission of UOF. RCC is a service ma7k of Ashland Oil Inc.)... 

Seelbach, K., Riebel, B., Hummel, W. etal. (1996) A novel, efficient regenerating method of NADPH using a new formate dehydrogenase. Tetrahedron Letters, 37, 1377-1380. 

The catalytic system has been successfully extended to polymer-bound lithium amide co-bases of type 65 (see Table 4) which, like C—Li bases of type 63 and 64, are efficient regenerating agents of HCLA and poorly reactive toward oxiranes. For instance, the isomerization of cyclohexene oxide by 0.05 equiv of HCLA 55 in the presence of 1.45 equiv of 65 affords ( l-cyclohexenol in 92% ee (entry 15). It is of interest to note that, similarly to co-bases 63 and 64, the use of 65 leads to an increase of selectivity compared to the stoichiometric reaction at room temperature (Table 2, entry. ... 

The inorganic portion of the soil is relatively unaffected, allowing for efficient regeneration of organic soil properties. 

For efficient regeneration, the catalyst should form only labile intermediates with the substrate. This concept can be realized using transition metal complexes because metal-ligand bonds are generally weaker than covalent bonds. The transition metals often exist in different oxidation states with only moderate differences in their oxidation potentials, thus offering the possibility of switching reversibly between the different oxidation states by redox reactions. 

Research on separation processes demonstrated that hydrophobic oilladen surfactant was efficiently regenerated through the use of state-of-the-art hollow fiber membrane columns. Specifically, the hydrophobic oil dodecane was effectively separated from the surfactant system SDBS/IPA/NaCl (Table VI). This separation was accomplished by counterflowing the oil/surfactant solution, comprised of 10.3 ml. dodecane per 100ml. of SDBS/IPA/NaCl solution, with the extraction solvent squalane. These results demonstrate the ability to effectively regenerate and reuse these surfactant systems. 

Generally, the nicotinamide coenzymes are not covalently bound to the enzyme. They are employed in enzyme assays and preparative applications by adding catalytical but optimized amounts, and they need to be recycled. For an economic process, an efficient regeneration method is a basic requirement. The necessary recycle number depends essentially on the value of the chiral product, generally the method should recycle the coenzyme 100-100,000 times ([42]). 

Phenidone-based developers keep better than those based on metol. The reason is the oxidation product of Phenidone is more efficiently regenerated by hydroquinone than is metol. 

A general method has been developed for utilization of cofactor-requiring enzymes in organic media [139]. ADH from horse liver as well as NADH were attached onto the surface of glass beads and afterwards suspended in a water-immiscible organic solvent containing the substrate. This method can be applied to other NAD+-dependent enzymes as well. Both NADH and NAD+ are efficiently regenerated with ADH-catalyzed oxidation of ethanol and reduction of isobutyr-aldehyde, respectively (Fig. 31). 

Presently, quite a lot of examples of enzymatic redox systems are known which include an efficient regenerating step and which are applied for large-scale manufacturing of important chiral compounds like fine chemicals or building blocks for pharmaceuticals in a very efficient way. 

Rhodopsin can be regenerated in vitro by adding 1 l-c -retinal to bleached rod outer segment membranes (ROS) in suspension or in a suitable detergent. The requirements for efficient regeneration are the following ... 

Based on these viewpoints, UOP developed the high-efficiency regenerator in 1974 with the following characteristics (Cabrera and Mott, 1982) ... 

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