Topic
Activated alumina
About: Activated alumina is a research topic. Over the lifetime, 1430 publications have been published within this topic receiving 31090 citations.
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Patent•
20 Nov 1992TL;DR: In this article, a combination of ceria, second metal oxide and activated alumina is used to oxidize gas phase components in a gas-borne stream, e.g., in a method to treat diesel engine exhaust.
Abstract: Oxidation catalyst compositions include a catalytic material having a BET surface area of at least about 10 m2/g and consisting essentially of a combination of bulk ceria and a bulk second metal oxide which may be one or more of titania, zirconia, ceria-zirconia, silica, alumina-silica and α-alumina. The combination may optionally also include activated alumina having a BET surface area of at least about 10 m2/g. The ceria, second metal oxide and optional activated alumina may be mixed together or provided as discrete layers. Optionally, one of platinum or palladium metal may be dispersed on the catalytic material provided that the platinum, when used, is used in limited amounts to preclude excessive oxidation of SO?2? to SO3. The catalyst compositions may be used for oxidation of oxidizable components in a gas-borne stream, e.g., in a method to treat diesel engine exhaust by contacting the hot exhaust with the catalyst composition to promote the oxidation of the volatile organic fraction. The optional inclusion of platinum or palladium promotes the oxidation of gas phase components, e.g., hydrocarbons and carbon monoxide.
37 citations
Patent•
13 Nov 1987
TL;DR: In this paper, a bed of desiccant material is irradiated with microwave energy with a frequency of from 2400 MHz to 2500 MHz or from 900 to 915 MHz to heat and substantially affect only moisture adsorbed by the material and to vaporize the moisture in consequence of the heating of the moisture.
Abstract: Porous desiccant material, such as silica gel, activated alumina, molecular sieves or mixtures thereof, is efficiently regenerated for reuse as a drying agent by irradiating a bed of the desiccant material with microwave energy preferably having a frequency of from 2400 MHz to 2500 MHz or from 900 to 915 MHz to heat and substantially affect only moisture adsorbed by the material and to vaporize the moisture in consequence of the heating of the moisture, the vaporized moisture being purged out of the bed with a forced draft of scavenging air while the bed undergoes irradiation by the microwave energy, and the resulting mixture of scavenging air and vapor being disposed of by discharging the mixture to an effluent receiving region isolated from the bed. As the moisture adsorbed on the pore, capillary and other surfaces of the desiccant material is preferentially heated by energy taken up from the microwave energy, moisture conversion from a liquid phase to a vapor phase is achieved directly, thereby to obviate raising the temperature of the desiccant material itself sufficiently to achieve the phase conversion of the adsorbate indirectly.
37 citations
TL;DR: In this paper, the synthesis and characterization of a hybrid adsorbent; hydroxyapatite-modified activated alumina (HMAA) prepared by dispersing nanoparticles of HAP inside activated granules was reported.
Abstract: Fluoride in drinking water is beneficial at low concentrations but is considered harmful for the human health when present at concentrations exceeding 1.5 mg/L. Prevalence of high concentration of fluoride in drinking water, combined with the nonavailability of alternate viable sources, makes the treatment of the contaminated water an essential task. In this study, we report the synthesis and characterization of a hybrid adsorbent; hydroxyapatite-modified activated alumina (HMAA) prepared by dispersing nanoparticles of hydroxyapatite inside activated alumina granules. The composite adsorbent provided a synergy toward fluoride removal from contaminated drinking water. The hybrid adsorbent possesses a maximum adsorption capacity of 14.4 mg F/g which is at least five times higher than the virgin-activated alumina, which has been used extensively for fluoride removal. HMAA was regenerated using six bed volumes of a solution containing commonly available innocuous chemicals. The adsorbent was subjected to multiple numbers of operating cycles within a column, each cycle consisting of one adsorption run followed by regeneration.
37 citations
TL;DR: A wide variety of aliphatic acid chlorides including an optically active one has been efficiently converted to their t-butyl esters under very mild reaction conditions by employing activated alumina as a catalyst.
36 citations
TL;DR: In this article, the results indicated that, of the three sorbents, bauxite has the highest fluoride adsorption capacity per unit area, but is limited by a low specific surface area.
36 citations