Abstract: A process for preparing silica having a low silanol content which comprises heating amorphous silica in an atmosphere of a low partial pressure of water vapor to maintain the amorphous silica at a temperature in a range of from 600.degree. to 1000.degree. C. at a first heating step and then maintain at a temperature of 1200.degree. C. or more at a second heating step. The silica having a low silanol content obtained according to the present invention is advantageously used as a raw material for quartz glass, particularly as a raw material for preparing crucibles used to pull up silicon single crystals.

Abstract: This invention deals with a process for manufacturing high purity silica which comprises making an aqueous alkali silicate solution into fine fibrous gel in a coagulant, treating the fibrous gel obtained with an acid-containing solution, and then with water to extract and remove impurities; and optionallly heating a resulting silica at a temperature of 1,000.degree. C. or higher. Thus obtained silica is preferably used as a filler, especially, the one for resin compositions for encapsulating electronic parts; etc.

Abstract: A process for the selective production of dimethylamine in preference to mono- and trimethylamines by a catalytic vapor phase reaction of ammonia and methanol over a zeolite selected from mordenite, clinoptilolite and erionite is disclosed, wherein the improvement is characterized by the fact that the zeolite used has been contacted with steam at a temperature of 250.degree. to 700.degree. C.

Abstract: Catalytic production of dimethylamine in preference to mono- and trimethylamine over a mordenite catalyst is disclosed, which mordenite is characterized by its alkali metal content.