Alumina carbon dioxide adsorbed

The strong inhibiting effect of water during the reduction of well-dispersed iron oxide phases on alumina surfaces is also apparent from the infrared spectrum of carbon monoxide adsorbed onto the reduced catalyst prepared from complex iron cyanides according to the above procedure of Boellaard and co-workers Despite the support, the size of the iron particles, and the loading of iron on the support all being essentially the same, the infrared spectrum of the adsorbed carbon monoxide is completely different. The absorption band at 2155 cm is not seen, which indicates that Fe(II) is not present at the alumina surface when reduced in the presence of low partial pressures of water vapor. Rather than bands with frequencies above about 2000 cm bands at 1806, 1884, and 1984 cm are observed (Fig. 5.9). Even at room temperature, disproportionation of carbon monoxide to carbon dioxide and carbon occurs, which is demonstrated by the presence of carbon dioxide adsorbed onto the alumina support. The infrared bands peaking at 1348 and 1598 cm arise from carbon dioxide adsorbed on alumina. 

A carbon dioxide yield of 25.3% was achieved when benzo [a] anthracene adsorbed on silica gel was irradiated with light (X >290 nm) for 17 h (Freitag et al, 1985). Behymer and Hites (1985) determined the effect of different substrates on the rate of photooxidation of benzo[a]anthracene using a rotary photoreactor. The photolytic half-lives of benzo[a]anthracene using silica gel, alumina, and fly ash were 4.0, 2.0, and 38 h, respectively. 

It is a mass transfer between a mobile, solid, or liquid phase, and the adsorption bed packed in a reactor. To carry out adsorption, a reactor, where a dynamic adsorption process will occur, is packed with an adsorbent [2], The adsorbents normally used for these applications are active carbons, zeolites and related materials, silica, mesoporous molecular sieves, alumina, titanium dioxide, magnesium oxide, clays, and pillared clays. 

The cryogenic air separation process starts with air entering the plant through air filters, where it is compressed and cooled. The air is passed through heat exchangers for further cooling and for removal of water vapor and carbon dioxide by freezing. Solid adsorbents, such as molecular sieves, silicas, and aluminas can also be used to remove the water and carbon dioxide by adsorption before separation of... 

A1203 activated by heating to about 200 C in a current of air or carbon dioxide, is the most, widely used absorbent. Other adsorbents used are silica gel (activated in the same manner as alumina), magnesium oxide, magnesium carbonate, calcium carbonate, calcium sulphate, barium carbonate, charocal, sucrose, talc, starch, cellulose and Fuller s earth. The inorganic adsorbents are usually heated to 200-220 C before use. 

Supercritical fluid extraction can be used to remove carbonaceous material from spent catalysts. De Filippi and Robey (2) used supercritical carbon dioxide extraction to regenerate adsorbents. Abel (3) tried supercritical carbon dioxide extraction to regenerate a certain catalyst. Tiltscher et al. (4,5) studied the isomerization of 1-hexene on an alumina catalyst and showed that under supercritical conditions, 1-hexene was able to remove the oligomeric compounds (C -C q) from t ie catalyst surface and prevent coking. 

Physical sorbents for carbon dioxide separation and removal were extensively studied by industrial gas companies. Zeolite 13X, activated alumina, and their improved versions are typically used for removing carbon dioxide and moisture from air in either a TSA or a PSA process. The sorption temperatures for these applications are usually close to ambient temperature. There are a few studies on adsorption of carbon dioxide at high temperatures. The carbon dioxide adsorption isotherms on two commercial sorbents hydrotalcite-like compounds, EXM911 and activated alumina made by LaRoche Industries, are displayed in Fig. 8.F23,i24] shown in Fig. 8, LaRoche activated alumina has a higher carbon dioxide capacity than the EXM911 at 300° C. However, the adsorption capacities on both sorbents are too low for any practical applications in carbon dioxide sorption at high temperature. Conventional physical sorbents are basically not effective for carbon dioxide capture at flue gas temperature (> 400°C). There is a need to develop effective sorbents that can adsorb carbon dioxide at flue gas temperature to significantly reduce the gas volume to be treated for carbon sequestration. 

In order to cross-check the preceding results with a second "chemical" method, experiments able to detect selectively the fraction of alumina surface uncovered by ceria were looked for. As other alumina-supported oxides [12-16], adsorption of carbon dioxide was considered. Preliminary volumetric results of the adsorption of carbon dioxide at room temperature, after calcination and outgassing under vacmun at 673 K, were not fiilly conclusive, as both ceria and alumina are able to chemisorb carbon dioxide further, although the adsorption strength of carbon dioxide is much lower on alumina than on ceria, experiments for isolating selective contribution of ceria, after desorption of CO2 from alumina at 373 K were also unsatisfactory, as some 20% of CO2 adsorbed on ceria was also desorbed during evacuation. 

The steam-carbon dioxide-hydrocarbon conversion is conducted over a catalyst such as nickel (oxide) on alumina. This type of catalyst can be purchased in quite similar composition from a number of catalyst vendors. In the case in which the feed stock is processed over a catalyst as in steam-hydrocarbon reforming, it is essential that the gas be purified, at least to some extent, prior to its passage over the reforming catalyst, particularly if the catalyst is of the typical composition of supported and promoted nickel (oxide). In steam hydrocarbon reforming, the methane (natural gas) is usually detoxified using an adsorbent such as carbon on which is impregnated suitable chemical adsorbents such as elemental iron or copper. There are at least two of these metallized carbon desulfurizers in parallel with one on... 

Y. Okamoto and T. Imanaka, Interaction chemistry between molybdena and alumina Infrared stndies of surface hydroxyl-groups and adsorbed carbon dioxide on aluminas modified with molybdate, snlfate, or flnorine anions, J. Phys. Chetn., 92(25), 7102-7112, 1988. 

As shown by Table 1, the only large-scale application of adsorbent aluminas prior to 1940 was as desiccants. Both air and natural gas dehydration were being routinely performed with waste-heat regeneration of the alumina columns. In later years, dehydration with aluminas was extended to cracked gas and heavier hydrocarbon streams, as well as those containing carbon dioxide and ammonia. 

Usually, under heating the destruction of organic compounds to be evaporated occurs on the surface of active alumina sorbents. This phenomenon results in the formation of harmful volatile compounds and the coke that decreases adsorbent capacity. Therefore, it seems more preferable to oxidize organic compounds to carbon dioxide and water during adsorbent regeneration. The processes and purification systems that combine the adsorption and the catalytic combustion regeneration were developed. The transition aluminas doped with catalytic... 

Pressure swing adsorption (PSA) is a gas purification process, which consists of the removal of impurities on adsorbent beds. The usual adsorbents and gases adsorbed thereon are molecular sieves for carbon monoxide, activated carbon for carbon dioxide, activated alumina or silica gel. lyuke et td. reported that the addition of tin onto activated carbon improved the efficiency of the adsorptive removal of carbon monoxide from hydrogen [420]. 

A similar procedure can be carried out with gases. This technique has been used with carbon dioxide as the adsorbate and nitrogen as the carrier gas (114]. Adsorbents used were y-alumina, Gasil and Degussa... 

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