Abstract:
The activity and stability of copper chromite catalysts have been found to be sensitive to both copper-to-chromium ratio and to alumina content. Alumina-containing catalysts of improved stability for the oxidation of carbon monoxide at high temperatures and the use of these catalysts in the control of automotive exhaust emissions are described.
Abstract:
This invention relates to the discovery of a method for incorporating various oxides into silica-containing porous and nonporous glass materials by dissolving soluble compounds of the additive oxides, characterized as MxOy, into solutions, colloidal solutions, or suspensions of soluble silicates, reacting the mixture with an organic compound, and then firing the thus-formed body at temperatures below the softening point of the particular glass composition for a sufficient length of time to produce the porous body or non-porous glass body containing the added oxides intimately bonded to the silica network.
Abstract:
SILICA-CONTAINING POROUS BODIES OF CONTROLLED PORE SIZE This invention relates to the preparation of silicacontaining particulate materials and monolithic structures exhibiting high porosity with exceptionally uniform pore size. The bodies are produced through gelation of aqueous alkali metal silicate and/or colloidal silica solutions, optionally containing dispersed particulate phases, with organic reagents followed by a leaching step. Uniformity of pore size is achieved through careful control of such variables as the ratio of alkali metal silicate to colloidal silica solutions, the concentration of silica, the amount of dispersed phase employed, and the like. Hence, for example, a porous silicate body having very closelycontrolled, small-sized pores would be eminently suitable for such applications as catalyst supports for air pollution control, filtration devices for gases and/or liquids, acoustical materials, and chromatographic supports.
Abstract:
The present invention relates to the production and chemical treatment of sodium and/or potassium hydrosilicate glasses containing about 5-50% by weight water within the glass structure, wherein the Na+ and/or K+ ions are capable of being partially completely replaced, on an electrolytically equivalent basis, by protons and/or other monovalent and polyvalent cations species, to make glass articles whose alkali metal oxide content is substantially diminished or completely removed. Such glass articles can be either completely dense, or microporous, with pores ranging down to molecular size. Moreover, the chemical compositions of such microporous glasses can be further altered to include many other chemical species including polyvalent cations, anions and neutral molecular species, both organic and inorganic, and including complex ions such as metal amine complexes, where such species are capable of being sorbed on the porous glass by physical or chemical forces or both. The instant invention provides means for replacing part or all of the Na+ and/or K+ ions in an alkali silicate hydrosilicate amorphous body either with protons, or with protons plus other monovalent or polyvalent cations, in the nondestructive manner by reaction in aqueous solutions. In addition, it provides means for incorporating many other chemical species into the ion-exchange microporous body at low temperature, by sorption from solutions, either aqueous or nonaqueous. These latter species are not necessarily cations. The processes of the invention make possible the alteration of the chemical composition of alkali hydrosilicate body to any of a wide variety of other glass compositions having better chemical durability and other useful glass properties.