Activated alumina

About: Activated alumina is a research topic. Over the lifetime, 1430 publications have been published within this topic receiving 31090 citations.

Manufacture of integral structure type catalyst for purifying waste gas

Abstract: PURPOSE:To increase the gas purifying degree and durability of the titled catalyst by mixing activated alumina having specified narrow pore diameter with alumina sol, crushing the mixture to make slurry and forming an aluminum oxide coating on the surface of a catalyst. CONSTITUTION:Activated alumina contg. cerium preliminarily wherein >=80% all narrow pore volume is occupied by the narrow pore volume of 200-600Angstrom narrow pore diameter is mixed with cerium oxide and alumina sol and the mixture is crushed and the obtained slurry is impregnated into an integral structure type carrier, dried and calcined and thereafter the essential catalytic metals are deposited on the composite oxide coating formed on the carrier. Separately, after the slurry of mixed and crushed material of both alumina wherein >=80% all narrow pore volume is occupied by the narrow pore volume of 200-600Angstrom narrow pore diameter and alumina sol is coated on the carrier deposited with the above-mentioned essential catalytic metals, it is dried, calcined to manufacture the waste gas purifying catalyst for removing carbon monoxide, hydrocarbons and nitrogen oxides contained in the waste gas.

Method of manufacturing alumina-based abrasive grain and alumina-based abrasive grain manufactured thereby

Abstract: Provided are a method of manufacturing an alumina-based abrasive grain, which includes preparing boehmite powder and activated alumina powder as starting materials, forming a sol by wet-blending and crushing the boehmite powder, the activated alumina powder, a solvent and a deflocculant, heating the sol at a first temperature which is higher than a room temperature and lower than a boiling point of the solvent and stirring the sol so as not to generate a precipitate, forming a gel by heating the sol at a second temperature higher than the first temperature at which a viscosity of the sol is increased and the sol becomes a paste, blending the gel with an organic solvent and performing wet crushing on the resulting mixture, preparing a powder by drying the wet-crushed gel, blending a binder and a solvent with the dried product, which is the powder, and molding the resulting mixture, calcining the molded product, performing dry crushing on the calcined product, and sintering the dry-crushed product to transform activated alumina and boehmite contained therein to an α-Al 2 O 3 crystal phase, and an alumina-based abrasive grain manufactured thereby. As a result, an alumina-based abrasive grain which is highly dense, has a high hardness, and exhibits a high purity may be manufactured using boehmite powder and activated alumina powder.

Arsenic(III) Immobilization on Rice Husk

Abstract: A number of large aquifers in various parts of the world have been identified with contamination by arsenic. Long-term exposure to arsenic in drinking water causes cancer of the skin, lungs, urinary bladder and kidney, as well as skin pigmentation and hyperkeratosis. Arsenic occurs in groundwater in two valence states, as trivalent arsenite [As(III)] and pentavalent arsenate [As(V)]. As(III) is more toxic and more difficult to remove from water by adsorption on activated alumina. In this study, immobilization (adsorption) of As(III) by quaternized rice husk was examined. Batch adsorption test showed that extent of adsorption was dependent on pH, As (III) concentration, contact time and rice husk dose. Maximum adsorption occurred at pH 7-8, and equilibrium adsorption was attained in 2 h. Equilibrium adsorption data were described by the Langmuir and Freundlich isotherm models. According to the Langmuir isotherm, adsorption capacity of quaternized rice husk is 0.775 mg As(III)/g, which is 4.3x higher than that (0.180 mg As(III)/g) of activated alumina. Quaternized rice husk is a potentially useful adsorbent for removing arsenic from groundwater.

Low-Grade Heat Utilization Through Ultrasound-Enhanced Desorption of Activated Alumina/Water for Thermal Energy Storage

Abstract: Sorption thermal energy storage (TES) seems to be an auspicious solution to overcome the issues of intermittent energy sources and utilization of low-grade heat. Ultrasound-assisted adsorption/desorption of water vapor on activated alumina is proposed as a means of low-grade heat utilization through TES. The effects of ultrasonic power on the storing stage (desorption of water vapor) were analyzed to optimize the desorption and overall efficiencies. To determine and justify the effectiveness of incorporating ultrasound from an energy-savings point of view, an approach of constant total (heat plus ultrasound) input power of 25 W was adopted. To measure the extent of the effectiveness of using ultrasound, ultrasonic-power-to-total power ratios of 0.2 and 0.4 were investigated and the results compared with those of no-ultrasound (heat only) at the same total power. The regeneration temperature and desorption rate were measured simultaneously to investigate the effects of ultrasonication on regeneration temperature and utilization of low-grade heat. The experimental results showed that using ultrasound facilitates the regeneration of activated alumina at both power ratios without increasing the total input power. With regard to regeneration temperature, incorporating ultrasound decreases the regeneration temperature hence justifying the utilization of low-grade heat for thermal energy purposes. In terms of overall energy recovery of the adsorption thermal storage process, a new metric is proposed to justify incorporating ultrasound and any other auxiliary energy along with low-grade heat.

Catalyst for hydrogenation treatment of light and medium liquefied oil of coal

Abstract: PURPOSE: To perform hydrogenation treatment of light and medium liquefied oils by using a catalyst formed by supporting Mo, W, Ni and Co or compds. of the metals on a porous activated alumina carrier having a specified average pore diameter. CONSTITUTION: Mo and W as group VIa metals of the periodic table, Ni and Co as group VIII metals or compds. of the metals are supported on a porous activated alumina carrier having 80-170Å average pore diameter to form a catalyst for hydrogenation treatment of light and medium liquefied oils from coal. A mixture contg. coal as raw material, a catalyst and a solvent is primarily hydrogenated and the resulting light and medium liquefied oils from the coal are subjected to hydrogenation treatment in the presence of the formed catalyst for hydrogenation treatment. By this method, the light and medium liquefied oils as fraction having about ≤420°C b.p. can be simultaneously subjected to hydrogenation treatment under hydrogen at high temp. and pressure. COPYRIGHT: (C)1990,JPO&Japio