Abstract: The present invention relates to a method of purifying strong acids or strongly acidic media to remove di- and higher valent metal ions, which can be used within the context of the production of high-purity silica. The invention further relates to the use of special ion exchangers for carrying out the method according to the invention and the resultant high-purity silicas.

Abstract: The present invention relates to a method of purifying strong acids or strongly acidic media to remove di- and higher valent metal ions, which can be used within the context of the production of high-purity silica. The invention further relates to the use of special ion exchangers for carrying out the method according to the invention and the resultant high-purity silicas.

Abstract: The present invention relates to a method of purifying strong acids or strongly acidic media to remove di- and higher valent metal ions, which can be used within the context of the production of high-purity silica. The invention further relates to the use of special ion exchangers for carrying out the method according to the invention and the resultant high-purity silicas.

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 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 object of the invention is a more energy-efficient system for utilizing waste heat and residual gases from the engineered generation of carbon compounds, such as carbon black, graphite or from sugar pyrolysis, using a coupling of energy-heat or a thermal heat-generating plant for generating electrical energy, in particular for operating melt furnaces, and/or for utilizing the waste heat in endothermal processes. The invention also relates to the use of waste heat.

Abstract: The precipitated silica has the following physico-chemical parameters: BET surface area (DIN 66131) in m2/g 400-600 DBP index (DIN 53601) in g/100 g 300-360 Compacted density (DIN 53194) in g/l  70-140 Grindometer value (ISO 1524) in &mgr;m 15-50 Size distribution index I <1.0 measured with a Malvern instrument Size distribution index I = d 90 - d 10 2 ⁢ d 50 This precipitated silica is prepared by milling a precipitated silica in accordance with DE-A 31 44 299 in a classifier mill or a fluidized bed counter-flow mill. A polyethylene wax emulsion may be added before the milling procedure.

Abstract: The precipitated silica has the following physico-chemical parameters: BET surface area (DIN 66131) in m2/g 400-600 DBP index (DIN 53601) in g/100 g 300-360 Compacted density (DIN 53194) in g/l  70-140 Grindometer value (ISO 1524) in &mgr;m 15-50 Size distribution index I <1.0 measured with a Malvern instrument Size ⁢   ⁢ distribution ⁢   ⁢ index ⁢   ⁢ I = d 90 - d 10 2 ⁢ d 50 This precipitated silica is prepared by milling a precipitated silica in accordance with DE-A 31 44 299 in a classifier mill or a fluidized bed counter-flow mill.

Abstract: Precipitated silica having the following parameters: BET surface area 80-180 m2/g CTAB surface area 80-139 m2/g BET/CTAB ratio 1.0-1.6 Sears No. (consumption of 5-25 ml 0.1 N NaOH) DBP No. 200-300 ml/100 g Al2O3 content <5% wk coefficient <3.4 Degraded particles <1.0 &mgr;m Non-degradable particles 1.0-100 &mgr;m is prepared by reacting alkali silicate with mineral acids and aluminum sulfate solution at temperatures of 60-95° C. at a pH of 7.0-10.0 while stirring constantly, wherein the reaction is continued to a solids concentration of 40-110 g/l, the pH is adjusted to a value between 3 and 5, and the precipitated silica is filtered off, washed and then dried, and optionally ground or granulated.

Abstract: Precipitated silica, having the following physico-chemical parameters: BET surface area 120-300 m2/g CTAB surface area 100-300 m2/g BET/CTAB ratio 0.8-1.3 Sears index (consumption of 6-25 ml 0.1 N NaOH) DBP index 150-300 g/100 g wk coefficient <3.4 Particle size of the degraded <1.0 &mgr;m particles Particle size of the non- 1.0-100 &mgr;m degradable particles The precipitated silica is prepared by a process in which an alkali metal silicate (preferably soda water-glass) is reacted with mineral acids (preferably sulfuric acid) at temperatures of 60-95° C. at a pH of 7.0-11.0 with continuous stirring, the reaction is continued up to a solids concentration of 40 g-110 g, the pH is adjusted to a value between 3 and 5, and the precipitated silica is filtered off, washed, then dried and, if appropriate, ground or granulated.

Abstract: A process for preparing microporous separating elements for batteries by intensive mixing of a high molecular weight polyethylene with a precipitated silica having specific chemical and physical characteristics, a process liquid and a stabilizer to form a powder mixture, which is extruded to form a film, from which the process liquid is removed, thereby leaving the desired microporous separating elements which are recovered.

Abstract: Precipitated silicas, characterized in that they have a CTAB surface area (in accordance with ASTM D 3765-92) of 200 to 400 m.sup.2 /g, a DBP index (in accordance with ASTM D 2414) between 230 and 380 ml/100 g as powder and 180-250 g/100 g as granulate, a silanol group density (V.sub.2 -NaOH consumption) of 20 to 30 ml and the following macropore size distribution which is typical of the surface area range involved, determined by means of Hg porosimetry (DIN 66 133) for specific pore size intervals (incremental mode of application):______________________________________ CTAB surface CTAB surface CTAB surface area range: area range: area range: 200-250 m.sup.2 /g 250-300 m.sup.2 /g 300-400 m.sup.2 /g Pore size interval ?nm! Hg consumption in ml/g of silica ______________________________________ 10-20 0.27-0.49 0.35-0.50 0.32-0.42 20-30 0.22-0.32 0.15-0.30 0.17-0.22 30-40 0.15-0.21 0.12-0.17 0.12-0.15 40-50 0.11-0.16 0.09-0.12 0.08-0.11 50-60 0.08-0.12 0.06-0.10 0.06-0.

Abstract: Precipitated silica with the following physical-chemical characteristics:______________________________________ BET surface: DIN 66131 100-130 m.sup.2 /g DBP absorption DIN 53601 .gtoreq.275 g/100 g (anhydrous) ASTM D 2414 Loss on drying DIN ISO 787/II (2 h/105.degree. C.) ASTM D 280 3.5-5.5 wt. % JIS K 5101/21 Oversize with ALPINE air-jet sieve: >63 .mu.m .ltoreq.10.0 wt. % >150 .mu.m .ltoreq.0.1 wt. % >250 .mu.m .ltoreq.0.01 wt. % Chloride content: .ltoreq.100 ppm ______________________________________is prepared by introducing water into a precipitation vessel, adding water glass until an alkali value of 5-15 is reached, then adding further water glass and sulfuric acid simultaneously, interrupting the precipitated silica suspension with sulfuric acid to a pH-value of 8.5, with stirring, then continuing acidification with concentrated sulfuric acid to a pH-value of 4, then separating and washing the precipitated silica which has a solids content in the suspension of approx.

Abstract: Precipitated silicas, characterized in that they have a CTAB surface area (in accordance with ASTM D 3765-92) of 200 to 400 m.sup.2 /g, a DBP index (in accordance with ASTM D 2414) between 230 and 380 ml/100 g as powder and 180-250 g/100 g as granulate, a silanol group density (V.sub.2 -NaOH consumption) of 20 to 30 ml and the following macropore size distribution which is typical of the surface area range involved, determined by means of Hg porosimetry (DIN 66 133) for specific pore size intervals (incremental mode of application):______________________________________ CTAB surface CTAB surface CTAB surface area range: area range: area range: 200-250 250-300 300-400 Pore size m.sup.2 /g m.sup.2 /g m.sup.2 /g interval ?nm! Hg consumption in ml/g of silica ______________________________________ 10-20 0.27-0.49 0.35-0.50 0.32-0.42 20-30 0.22-0.32 0.15-0.30 0.17-0.22 30-40 0.15-0.21 0.12-0.17 0.12-0.15 40-50 0.11-0.16 0.09-0.12 0.08-0.11 50-60 0.08-0.12 0.06-0.10 0.06-0.

Abstract: A zeolite catalyst and a method for reduction of nitrogen oxides present in waste gas streams is described. The method includes mixing the waste gas containing nitrogen oxides with ammonia. At an elevated temperature, this mixture is passed over a zeolite catalyst. Preferably, the zeolite catalyst is in a monolithic or honeycomb form. The zeolite catalyst includes one or more of the following subgroup metals: copper, iron, molybdeum and cerium. The zeolite catalysts made in accordance with this invention show better conversion of nitrogen oxides and longer life than known catalysts.

Abstract: A method for producing tetrapropylammonium bromide by reacting tripropylamine with propyl bromide in a polar solvent at a temperature between 60.degree. and 160.degree. C.