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•
01 Nov 1986
TL;DR: In this article, the surface of a carrier is covered with an aqueous catalyst slurry to uniformize pore distribution and to enhance purifying capacity, by applying a wash-coating method.
Abstract: PURPOSE:To uniformize pore distribution and to enhance purifying capacity, by coating the surface of a carrier with an aqueous catalyst slurry to which a combustible substance and a combustible org. solvent were added and removing the excessive aqueous catalyst slurry before baking. CONSTITUTION:A combustible substance 2 such as powdery activated carbon, a combustible org. solvent 3 such as light oil and a surfactant 4 are added under stirring to an aqueous catalyst slurry 1 prepared by mixing activated alumina with water to which a small amount of nitric acid was added. The obtained aqueous catalyst slurry 1 is applied to the surface of a ceramic carrier 5 according to a wash-coating method to form a wash-coat layer 6 and air blow is subsequently applied to the wash-coat layer on the surface of the carrier 5 to remove the excessive aqueous catalyst slurry. Thereafter, baking is performed to burn off the combustible substance 2 and the combustible org. solvent 3 to obtain a catalyst structure wherein pores 7 are formed to the surface of the layer 6.
6 citations
TL;DR: In this article, an investigation combining thermal analysis (TA), on-line coupled to mass spectrometry (MS), with ESR spectroscopy was conducted to identify trapped NO2 molecules as well as to follow the mechanically and thermally induced changes of the Al−O−H matrix via the contained (or doped) Fe3+ impurities.
Abstract: Exothermal differential thermal analysis (DTA) effects for water release have been observed both for mechanically activated alumina gels, which may contain residual nitrate, and for strongly amorphisized AlO(OH) gels at comparably low temperatures (150−350 °C) under hydrogen. The observations are based on an investigation combining thermal analysis (TA), on-line coupled to mass spectrometry (MS), with ESR spectroscopy. This allowed the identification and quantification of trapped NO2 molecules as well as to follow the mechanically and thermally induced changes of the Al−O−H matrix via the contained (or doped) Fe3+ impurities. The appearance of the exothermal DTA effects is related not only to a strong mechanical activation and the access of hydrogen during the thermal treatment but also to the interaction of hydrogen with metallic platinum, for exampel, as crucible material or as metal powder. This interaction is discussed to be the origin of the chain start of the radical reaction between H2 and NO2 yiel...
6 citations
Patent•
03 Oct 1986
TL;DR: In this article, the authors proposed to enhance the purifying action of a ternary catalyst by forming the platinum group element fixed to activated alumina into an aqueous slurry along with a cerium hydroxide powder.
Abstract: PURPOSE:To enhance the purifying action of a ternary catalyst, by forming the platinum group element fixed to activated alumina into an aqueous slurry along with a cerium hydroxide powder and applying said aqueous slurry to a monolithic carrier before additionally applying the other component. CONSTITUTION:At least one of compounds of platinum group elements are supported by an activated alumina powder in a dispersed state to fix at least one of platinum group metals onto activated alumina. This supported platinum group element composition is formed into an aqueous slurry along with a cerium hydroxide powder to prepare a slurry composition which is, in turn, applied to a monolithic carrier. On the other hand, a rhodium compound is supported by an activated alumina powder in a dispersed state to fix rhodium onto activated alumina while the obtained composition is formed into an aqueous slurry which is, in turn, additionally applied to the monolithic carrier, to which the aforementioned coating treatment was applied, to form an exhaust gas purifying catalyst.
6 citations
Patent•
19 Feb 1987TL;DR: In this article, the authors present a process for preparing granules of alumina by admixing with cold water in a mixer at a temperature below room temperature, e.g., such as below about 20°C, to form a pretreated alumina having a pore volume saturated with water and further having a surface area of gel structure.
Abstract: The process of the present invention for preparing granules of alumina includes pretreating an alumina powder by admixing with cold water in a mixer at a temperature below room temperature, e.g., such as below about 20° C., to form a pretreated alumina having a pore volume saturated with water and further having a surface area of gel structure, and agglomerating the pretreated alumina in a fluidized bed to form granules sized in the range of about 1-3 mm. The process is particularly suited to producing activated alumina in macroporous granules. The process in one aspect further includes a cold hopper for cooling alumina powder prior to the pretreating step.
6 citations
TL;DR: In this article, the fluoride concentrations in the krill oils were positively correlated with protein concentrations, and absorbents were employed to remove fluoride from the KOs and protein removal rates were correlated with the fluoride removal rates.
Abstract: Krill oils (KOs) were prepared using different extraction methods (hexane and supercritical carbon dioxide), different materials (heat-dried krill powder, freeze-dried krill powder, and freeze-dried krill tail meat powder), and different standing times during hexane extraction. The fluoride concentrations in the KOs were positively correlated with the protein concentrations. Absorbents were employed to remove fluoride from KO. Activated clay achieved the highest fluoride removal rate (70.66%), followed by calcium oxide (14.49%), activated carbon (11.97%), calcium chloride (9.32%), activated alumina (0.94%), and chitosan (0.52%). Meanwhile, the protein removal rates of the above absorbents were positively correlated with the fluoride removal rates.
6 citations