Activated alumina

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

Epoxidation using hydrogen peroxide and tungsten catalysts

Abstract: Alkenes can be epoxidised with hydrogen peroxide using a homogeneous heavy metal catalyst, but discharge of spent reaction mixtures releases the heavy metal in the environment. The problem can be ameliorated by selecting a heterogeneous catalyst system comprising a tungsten-containing heteropolyacid supported on selected Group IIa, IIb, IIIb, IVa or IVb inorganic supports or on a strong basic resin, which catalyst has either been calcined after impregnation or in the impregnation stage an alcoholic solution of the heteropolyacid is employed and by employing a nitrilo or oxygenated polar solvent reaction medium. A number of preferred heteropolyacids satisfy the empirical formula M3/nPWwMO12-wO40 in which w represents an integer of at least 1, M represents a counterion and n its basicity. Preferred supports include activated alumina, calcined at 400 to 600° C and cross-linked quaternary ammonium-substituted polystyrene resins. The most preferred catalysts are made by impregnating an inorganic support with a methanol solution of the heteropolyacid to a desired loading of active material on the support and subsequently calcining the loaded support at 400 to 600° C. Preferred reaction media include acetonitrile and tertiary butanol.

Removal of phenol by activated alumina bed in pulsed high-voltage electric field.

Abstract: A new process for removing the pollutants in aqueous solution-activated alumina bed in pulsed high-voltage electric field was investigated for the removal of phenol under different conditions. The experimental results indicated the increase in removal rate with increasing applied voltage, increasing pH value of the solution, aeration, and adding Fe 2+ . The removal rate of phenol could reach 72.1% when air aeration flow rate was 1200 ml/min, and 88.2% when 0.05 mmol/ LF e 2+ was added into the solution under the conditions of applied voltage 25 kV, initial phenol concentration of 5 mg/L, and initial pH value 5.5. The addition of sodium carbonate reduced the phenol removal rate. In the pulsed high-voltage electric field, local discharge occurred at the surface of activated alumina, which promoted phenol degradation in the thin water film. At the same time, the space-time distribution of gas-liquid phases was more uniform and the contact areas of the activated species generated from the discharge and the pollutant molecules were much wider due to the effect of the activated alumina bed. The synthetical effects of the pulsed high-voltage electric field and the activated alumina particles accelerated phenol degradation.

Activated alumina Claus catalyst having increased sodium oxide content

Abstract: An improved Claus catalyst comprising activated alumina in which sodium oxide concentration is controlled to achieve increased sulfur conversion. Sodium oxide is present in an amount greater than 0.50 wt % (1100° C. calcined basis), the remainder being activated alumina. Specific surface area is greater than 100 m2 /g (BET). In a preferred embodiment, sodium oxide content is controlled in the range 1.0 to 2.5 wt %. The catalyst preferably has a surface area greater than 300 m2 /g (BET) and an LOI (hydroxyl content as determined by heating from 400° to 1100° C.) between 2.0 and 6.0 wt %.

Process for the manufacture of spherical alumina-containing particles

Abstract: Disclosed is process for the preparation of alumina-containing particles, comprising the steps of (a) mixing an aluminum oxide hydrosol containing a hydrate of alumina or activated alumina and an additive component selected from a high molecular weight natural organic material which is insoluble in aqueous solution up to a temperature of 50° C. and carbon with a solution of hydrolyzable base to form a mixture; (b) introducing the mixture in dispersed form into a water-immiscible liquid having a temperature of from about 60 to 100° C., whereby gel particles are formed; (c) aging the gel particles in the liquid at the temperature and subsequently in an aqueous ammonia solution; (d) recovering the aged particles; and (e) calcining the recovered particles.

Color filter with a porous activated film layer having dye fixed in the minute pores to form color or pattern

Abstract: The color filter of this invention comprises a transparent substrate, a porous activated film layer formed on the substrate and made of activated alumina or activated silica or a mixture thereof, a colored area or a pattern formed by the dye fixed in the minute pores of the activated film layer, and a coating layer sealingly closing the upper portions of the minute pores of said activated film layer. This color filter is relatively simple and easy to manufacture, superior in resistivity to heat, water, chemicals, solvents, etc. and suitable for use as a color filter in various display devices, particularly liquid crystal display devices.