Abstract:
The invention relates to a complete method for producing pure silicon that is suitable for use as solar-grade silicon, comprising the reduction of a silicon oxide, purified by acidic precipitation from an aqueous solution of a silicon oxide dissolved in an aqueous phase, using one or more pure carbon sources, the purified silicon oxide being obtained, in particular, by the precipitation of a silicon oxide dissolved in an aqueous phase in an acidifier. The invention also relates to a formulation containing an activator and to a device for producing silicon, a reactor and electrodes.
Abstract:
The present invention relates to methods for the technical pyrolysis of a carbohydrate or carbohydrate mixture at an elevated temperature while adding silicon oxide, to a pyrolysis product obtainable in this way, and to the use thereof as a reducing agent for the production of solar silicon from silicic acid and carbon at a high temperature.
Abstract:
The invention relates to a method for converting silicon tetrachloride having hydrogen to trichlorosilane in a hydrodechlorination reactor, wherein the hydrodechlorination reactor is operated under pressure and comprises one or more reactor tubes which are made of a ceramic material. The invention further relates to the use of such a hydrodechlorination reactor as an integral component of a system for producing trichlorosilane from metallurgical silicon.
Abstract:
The invention relates to a complete method for producing pure silicon that is suitable for use as solar-grade silicon, comprising the reduction of a purified silicon oxide using one or more pure carbon sources, the purified silicon oxide, which was purified as silicon oxide dissolved in an aqueous phase, having a content of other polyvalent metals or metal oxides, in relation to the silicon oxide, of less than or equal to 300 ppm, preferably less than 100 ppm, especially preferably less than 50 ppm and according to the invention less than 10 ppm of the other metals and being obtained advantageously by gel formation in alkaline conditions. The invention also relates to a formulation containing an activator and to the use of purified silicon oxide together with an activator for producing silicon.
Abstract:
The invention relates to a process for increasing the selectivity of the hydrogenation of 4,4'-diaminodiphenylmethane (4,4'-MDA) to diaminodicyclohexylmethane (4,4'-HMDA) by catalytic hydrogenation of a mixture containing 4,4'-MDA as the main component and its mono-N-methyl derivative as a secondary component. According to the invention, the hydrogenation is terminated before a conversion of 4,4'-MDA to 4,4'-HMDA of 99% is achieved. Under these conditions, a substantially smaller proportion of the N-methyl-4,4'-MDA is hydrogenated to N-methyl-4,4-HMDA.