Abstract: An improved supercritical drying process for forming transparent silica aerogel arrays is described. The process is of the type utilizing the steps of hydrolyzing and condensing aloxides to form alcogels. A subsequent step removes the alcohol to form aerogels. The improvement includes the additional step, after alcogels are formed, of substituting a solvent, such as CO.sub.2, for the alcohol in the alcogels, the solvent having a critical temperature less than the critical temperature of the alcohol. The resulting gels are dried at a supercritical temperature for the selected solvent, such as CO.sub.2, to thereby provide a transparent aerogel array within a substantially reduced (days-to-hours) time period. The supercritical drying occurs at about 40.degree. C. instead of at about 270.degree. C. The improved process provides increased yields of large scale, structurally sound arrays.
September 4, 1985
Date of Patent:
September 9, 1986
The United States of America as represented by the United States Department of Energy
Abstract: A process for removing iron pentacarbonyl from carbon monoxide feed gas, comprising contacting the gas with a removal agent comprising alkali metal hydroxide in association with a high boiling hydroxylic solvent to form a nonvolatile iron carbonylate salt, and separating the gas from said agent and the salt. Preferably, the removal agent is adsorbed on a porous support such as diatomaceous earth at a concentration of from about 1% to about 40% by weight of the support, and the solvent is selected from one or mixtures of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 2,2,4-trimethyl-1,3-pentanediol, glycerine, triethanolamine, 1,4-butanediol, 1,2-propanediol, 1,3-butanediol, 2,5-hexanediol, 1-hexanol and 2-hexanol.
Abstract: The invention relates to the preparation of silicon tetrachloride by reacting material containing SiO.sub.2 with chlorine in the presence of carbon and metal halides and especially chlorides of the fifth main or subsidiary group of the Periodic Table at temperatures in the range of from 500.degree. to 1200.degree. C. The material containing SiO.sub.2 has a BET surface area of at least 0.1 m.sup.2 /g and the carbon has a BET surface area of at least 0.5 m.sup.2 /g.
Abstract: Silane is efficiently converted to disilane by irradiation at pressures in excess of about 75 torr using pulsed coherent light having a wavelength in the range from about 10.2 to about 11.2 .mu.m.
Abstract: There is disclosed a method for making high strength carbon fibers which comprises carbonizing acrylic fibers applied with an aqueous dispersion of a silicone compound represented by the following general formula [I] dispersed with an emulsifier represented by the following general formula [II], the total amount of the silicone compound and the emulsifier being 0.01 to 10.0% by weight (owf) and the weight ratio of the emulsifier to the silicone compound being 0.05 to 0.4: ##STR1## (where the symbols are as defined hereinbefore).
Abstract: The invention relates to a process for the continuous wet or wet-catalytic purification of waste gases by adsorption and chemisorption of the gaseous pollutants on activated carbons with simultaneous desorption of these pollutants or their reaction products. The process is carried out at 100 to 800 times gravity acceleration in a centrifugal filter, in the rotor of which a bed of fine-grain or fibrous activated carbon is arranged. The waste gas passes through this bed in codirectional or counter-current flow to the wash liquid. The pollutants are washed out with the desorbent flowing from the center outwardly.
Abstract: Methyl isocyanate in waste gaseous emissions is abated at temperatures substantially lower than those required in the conventional operation of a Process Thermal Oxidizer by contacting the waste gaseous emission with one or more transition metal oxide catalysts at a temperature of at least about 400.degree. C.
September 4, 1985
Date of Patent:
April 29, 1986
George F. Chadwick, Lawrence A. Kennedy