Abstract: A process for the preparation of alkylhalogenosilanes by reaction of silicon with an alkyl halide in the presence of a copper catalyst and promoter substances, the improvement wherein gaseous phosphorus compounds are admixed, as promotor substances, with the stream of alkyl halide.

Abstract: In the removal of water from a gas by contact with sulfuric acid, the improvement which comprises supplying the sulfuric acid in finely divided form having a surface of about 10.sup.4 to 10.sup.7 m.sup.2 /h at a concentration of about 95 to 99% and a temperature of about 35.degree. to 80.degree. C and with a contact time of about 0.2 to 2 seconds, whereby the residual moisture content of the gas is reduced to about 30 to 250 mg of H.sub.2 O/Nm.sup.3. Preferably the sulfuric acid is sprayed through a constriction into a vessel through which the gas is passed. The large sulfuric acid surface area permits high levels of dehydration to be achieved with far less sulfuric acid than heretofore believed possible and with small vessels and minimal contact times. Contact may be effected serially in several stages with the spent acids combined, brought up to initial concentration and recirculated.

Abstract: In the processing of a corrosive liquid mixture, such as 50 to 80% aqueous sulfuric acid, by its passage over one surface of a wall of inert heat resistant material, and heating the other surface of said wall, thereby to evaporate from said corrosive liquid mixture the more volatile component thereof, the improvement which comprises heating said wall by contact with an inert liquid material, and heating said inert liquid material indirectly through heat exchange with a normally solid molten material. Desirably the wall of inert material is a pipe surrounded by a molten metal in a first annular jacket and a molten salt in a second annular jacket.

Abstract: In the processing of a corrosive liquid mixture, such as 50 to 80% aqueous sulfuric acid, by its passage over one surface of a wall of inert heat resistant material, and heating the other surface of said wall, thereby to evaporate from said corrosive liquid mixture the more volatile component thereof, the improvement which comprises heating said wall by contact with an inert liquid material, and heating said inert liquid material indirectly through heat exchange with a normally solid molten material. Desirably the wall of inert material is a pipe surrounded by a molten metal in a first annular jacket and a molten salt in a second annular jacket.