Regenerative adsorbents

Silica gel is a regenerative adsorbant consisting of amorphous silica derived from sodium silicate and sulfuric acid. In addition lo color... 

CAS 7631-86-9. (sibca, amorphous hydrated silicic acid). A regenerative adsorbent consisting of amorphous sibca. Noncombustible. 

CAS 63231-67-4 977052-02-0 EINECS/ELINCS 231-545-4 Synonyms Metasilicic acid Silica aerogel Definition A regenerative adsorbent consisting of coherenL continuous three-dimensional network of spherical particles of colloidal silica Empirical OiSi Formula SiOj... 

Definition A regenerative adsorbent consisting of coherent, continuous three-dimensional network of spherical particles of colloidal silica... 

The residual traces of water and other components, such as odorants, are removed in regenerative adsorbers filled with molecular sieve or silica gel and activated carbon. Typically the unit operates according to the following automatic sequence ... 

The appHcations of adsorbents are many and varied and may be classified as nonregenerative uses, in which the adsorbent is used once and discarded, and regenerative appHcations, in which the adsorbent is used repeatedly in a cycHc manner involving sequential adsorption and regeneration steps. 

Adsorbent drying systems are typicaHy operated in a regenerative mode with an adsorption half-cycle to remove water from the process stream and a desorption half-cycle to remove water from the adsorbent and to prepare it for another adsorption half-cycle (8,30,31). UsuaHy, two beds are employed to aHow for continuous processing. In most cases, some residual water remains on the adsorbent after the desorption half-cycle because complete removal is not economically practical. The difference between the amount of water removed during the adsorption and desorption half-cycle is termed the differential loading, which is the working capacity available for dehydration. 

Many compounds can cause problems in pollutant-control equipment. Particulate matter, liquids, or solids in the waste stream can plug the adsorber beds, heat-recovery beds in regenerative thermal incinerator systems and biofilters. Conventional filtration systems are used to remove particulate matter before or after the process. 

The authors considered three mechanisms, including (a) a regenerative (redox) mechanism like that of Weibel,359 (b) the associative (formate) mechanism of Shido and Iwasawa360,361 that has some aspects in common with the formate mechanism of Grenoble et al.229 and (c) a CO decomposition mechanism by Yao,345 which was deemed unlikely as CO generally adsorbed on the metal, and does not decompose. 

To demonstrate the potential available, simulations were carried out for the oxidation of carbon monoxide on a palladium shell catalyst with water desorption from 3A zeolite as a heat sink, based on experimentally validated model parameters for the individual steps (Figure 16). The calculations indicated that the reaction cycle time could be lengthened by a factor of 10, to a total 20 minutes, in comparison to a simple regenerative process with a similar amount of inert material instead of adsorbent in the fixed bed and for the same threshold for temperature deviation from the initial value. 

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