Abstract: A process for producing silica in fine powder form, which comprises(a) adding at least one water-miscible alcohol selected from water-miscible monohydric and dihydric alcohols to an aqueous solution of an alkali metal silicate having an SiO.sub.2 concentration of 9 to 20% by weight until a solid precipitate forms and the solution begins, or is about, to become turbid,(b) adding a mineral acid to the resulting mixture in an amount 35 to 80% of the stoichiometrical amount required to neutralize the alkali metal silicate to precipitate silica as a fine powder, and(c) thereafter bringing the resulting slurry into contact with a mineral acid under an acidity of at least 1N.

Abstract: The process selectively absorbs hydrogen sulphide from gases containing hydrogen sulphide and carbon dioxide by contacting the gas with an aqueous solution of alkanolamine in an absorber column containing a structured packing consisting of a number of corrugated plates arranged parallel to the column axis. The corrugations are angled to the column axis at an angle between 20.degree. and 70.degree. and run in opposite directions on adjacent plates. The structured packing effects a lower absorption of the carbon dioxide in the solvent than Pall rings or sieve trays so that only a small amount of carbon dioxide is co-absorbed with the hydrogen sulphide.

Abstract: A process is disclosed for the melt consolidation of silicon powder which is based on the use of a critical partial vacuum of 200-300 torr of an inert gas that is applied.

Abstract: This invention concerns a process for purifying silica produced from an alkali silicate aqueous solution, which usually contains more than 200 ppm of impurities, to silica containing less than 30 ppm of impurities. Concretely, the purification process of silica comprises: dispersing silica gel, containing a lot of impurities, in water and filtering the solution; dispersing the filtered out silica gel again in an aqueous solution of pH 2 or less and filtering the aqueous solution; putting the silica gel to heat-treatment and acid-treatment with continuous stirring in order to break the inside siloxane link and dissolve out impurities therefrom and filtering the acid solution; rinsing a produced cake with pure water to wash away the inside residual solution and drying the cake.

Abstract: A process is disclosed for producing high purity silicon nitride. The process involves contacting an organic compound which can be decomposed into silicon dioxide with essentially anhydrous ammonia at ambient temperature to form a two phase system consisting essentially of ammonia gas and the vapor of the organic compound and heating the two phase system at a sufficient temperature for a sufficient time to form the high purity silicon nitride.

Abstract: A stratum of mercury is formed in an atmosphere, for example, helium gas. A liquid material is dropped to the surface of the mercury stratum. Since the surface tension of the mercury is larger than that of the liquid material, the liquid material rapidly spreads over the surface of the mercury stratum. As a result, a film is formed or a crystal grows on the surface of the mercury stratum. A DC voltage is applied between the liquid material and the mercury stratum. The resultant capillary electrical phenomenon momentarily spreads the liquid material over the surface of the mercury stratum. Thus, a good film is formed or a good crystal grows.

Abstract: Process for the removal of hydrogen sulphide from a gas mixture comprising passing the gas mixture through a reactor (2) filled with catalyst for the conversion of hydrogen sulphide to carbonyl sulphide, and separating the gas mixture leaving reactor (2) in a separator (7) at a temperature below the boiling point of carbonyl suplhide in a lighter fraction and a heavier fraction in which the carbonyl sulphide is absorbed.

Abstract: For the removal of sulfur compounds, especially H.sub.2 S, from gases that contain hydrocarbons, and/or CO.sub.2, the gases are scrubbed with a physical solvent, which is to be regenerated and reused. To obtain sulfur free of hydrocarbons, as well as a practically sulfur-free LPG fraction and optionally a C.sub.5+ fraction, an oxidizing agent is added to the solvent for reacting the sulfur compounds to elemental sulfur, and the sulfur is separated. The concomitantly absorbed hydrocarbons and/or CO.sub.2 can then be desorbed from the separated solvent by physical regeneration and can be recovered.

Abstract: A method for producing silicon which comprises subjecting silane and chlorine to a combustion reaction to generate a flame and thereby precipitating fine crystals of silicon.

Abstract: A process of fabricating a hybrid single crystal fiber having nonlinear optical properties such as frequency doubling. Said process includes placing a fiber core upon a bulk nonlinear crystal such as LiIO.sub.3 in a saturated growth solution of LiIO.sub.3 in water. After the core is encased a sufficient distance crystal growth is stopped.

Abstract: A method for removing hydrogen sulfide from a gaseous stream by contacting the gaseous stream with a polyvalent metal chelate present in an aqueous alkaline scrubbing solution including the regeneration of the polyvalent metal chelate in an electrolytic cell and automatic control of the pH of said aqueous alkaline scrubbing solution at about 7 to 9.

Abstract: A process is disclosed for the production of elemental silicon that utilizes a non-reactive condensible gas as a means for purging the reactor of ambient air prior to the introduction of an alkali metal and a silicon tetrahalide.

Abstract: A process for preparing fine fibers (or whiskers) consisting of carbon and silicon is disclosed, in which a mixed gas of transition metal compound(s), organo-silicon compound(s) and optionally carbon compound(s) is reacted at a high temperature, such as in the range of 700.degree. to 1,450.degree. C.

Abstract: Disilane Si.sub.2 H.sub.6 is obtained with good yield by reduction reaction of Si.sub.2 Cl.sub.6 with a mixture of LiH and LiAlH.sub.4 in an organic liquid medium such as n-butyl ether. Usually the reaction temperature is -25.degree. C. to 50.degree. C. A suitable range of the mole ratio of LiH to LiAlH.sub.4 is from 0.8 to 40. It is impracticable to reduce Si.sub.2 Cl.sub.6 to Si.sub.2 H.sub.6 by using LiH alone as the reducing agent, but the reaction proceeds smoothly when a LiH/LiAlH.sub.4 mixture is used. The use of the mixture is economically advantageous over the use of expensive LiAlH.sub.4 alone.

Abstract: Process for the absorption of hydrogen sulphide impurity from gases or liquid hydrocarbons comprising:(a) washing the gas or liquid hydrocarbon containing hydrogen sulphide with an aqueous alkaline solution of(a1) one or more compounds having the formula: ##STR1## or a water-soluble salt thereof, wherein m is 0 or 1 and R is a hydrogen atom or a methyl or carboxy group, and(a2) one or more compounds of a metal capable of existing in at least two valency states;(b) removing sulphur formed by oxidation of hydrogen sulphide; and(c) re-oxidizing the hydroquinone formed from reduction of the compound of formula I.

Abstract: A process for the removal of hydrogen sulfide from sour gas or other gases produced upon the retorting of shale by the injection of an aqueous ammonia solution. Further, this process reduces the amount of arsenic present in product oil formed in the retort process.

Abstract: A process is disclosed for producing high purity high surface area silicon nitride. The process involves contacting silicon tetrachloride with water to form a two phase system consisting essentially of a solid phase which is essentially silica gel and a liquid phase, heating the two phase system at a sufficient temperature for a sufficient time to partially dehydrate the silica gel followed by removing the solid phase from the liquid phase. A slurry is then formed of the solid phase in an aqueous solution of a water soluble organic carbon source. A dispersing agent is added to the slurry to disperse the silica gel, and the pH of the slurry is adjusted to greater than about 7, followed by heating the slurry at a sufficient temperature for a sufficient time to remove essentially all of the water and to decompose the carbon source.

Abstract: A process for the removal of cyanide complex or complexes from synthesis gas streams also containing residual iron containing particulate matter is disclosed, the process being characterized by scrubbing of the synthesis gas stream with water or an aqueous stream, removal of absorbed HCN, if any, from solution used in scrubbing, and contact of substantially HCN-free scrubbing solution with a polysulfide reactant at temperatures of from 110.degree. C. to 180.degree. C.

Abstract: A process for the removal of H.sub.2 S from a fluid stream whereby the H.sub.2 S is converted to soluble sulfur compounds by treatment with a solution of ferric chelates containing an oxidizing agent and a water soluble cationic polymeric catalyst such as poly(dimethyldiallyl ammonium chloride).

Abstract: A method of simultaneously removing SO.sub.2 and NO from oxygen-containing flue gases resulting from the combustion of carbonaceous material by contacting the flue gas with an aqueous scrubber solution containing an aqueous sulfur dioxide sorbent and an active metal chelating agent which promotes a reaction between dissolved SO.sub.2 and dissolved NO to form hydroxylamine N-sulfonates. The hydroxylamine sulfonates are then separated from the scrubber solution which is recycled.