Siemens Aktiengesellschaft

Hans-Peter Urbach

Hubert Aulich

Karl-Heinz Eisenrith

Friedrich-Wilhelm Schulze

The present invention provides a heterogeneous catalyst based on silicon dioxide, as well as, a method for manufacturing same. The catalyst of the present invention is constructed from a porous material produced from large-surface glass bodies containing catalytically active additives by leaching with mineral acid and the additives are incorporated into the network of the glass body in the form of metal oxides insoluble in hot mineral acid. The catalyst exhibits a high active surface and is universally employable because it contains only a slight amount of undesired impurities, is highly reactive, and has a high structural stability up to about 1000.degree. C.

Heterogeneous catalyst containing silicon dioxide

The invention concerns a process for the manufacture of substrates from carbon-coated SiO.sub.2 fabric that can be used for large-surface silicon bodies, in which mineral materials or waste containing SiO.sub.2 are used as starting materials and a mixture of Al.sub.2 O.sub.3 and oxides of the alkaline and/or alkaline earth metals is used as a flux for the transformation into the glass phase. The glass fibers made from the homogenous glass melt are processed into a glass fabric, which is then subjected to an acid leaching process and coated with carbon. The process is used for the low-cost production of substrates for silicon bodies that are manufactured according to the strip-coating process for use in solar cells.

Process for the manufacture of substrates from carbon-coated silicon

Highly purified starting materials for the production of silicon suitable for fabrication of solar cells are produced via the carbo-thermal reduction process. A carbon-containing material with impurities therein, either by itself or admixed with glass bodies, which are attained from a melt of quartz sand and glass-forming additives formed into a fiber form and pulverized, is converted into a granulate form with the aid of a bonding agent. The resultant granulates are contacted with a hot inorganic acid, such as 3N HCl at about 90.degree. C., to extract substantially all impurities from the granulates, which can be in pellet or tablet form. The resultant purified pellets are then directly charged into an electrical arc furnace to yield solar-quality silicon. With this process, highly purified SiO.sub.2 and highly purified carbon are produced in a simple and cheap manner. The impurity level for boron, phosphorus and transition metal in these starting materials is less than about 10 ppm.

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Munich, Germany

Hans-Peter Urbach