摘要:
Nanoscalar, pyrogenically produced yttrium-zirconium mixed oxide which has a BET surface area of between 1 and 600 m2/g, a total chloride content of less than 0.05 wt. % and does not exhibit a conversion into the monoclinic phase during storage is produced by atomizing yttrium compounds and zirconium compounds and reacting them in a flame. The mixed oxide can be used as ceramic raw material.
摘要:
Slip containing at least one aluminium oxide powder and at least one unstabilized zirconium dioxide powder, wherein a) the zirconium dioxide powder i) has a mean particle diameter of less than 300 nm, ii) shows only the monoclinic phase and the tetragonal phase in the X-ray diffraction pattern, with the proportion of tetragonal phase at room temperature being from 20 to 70%, and iii) is present in a proportion of from 2 to 20% by weight, based on the total amount of the slip, b) the aluminium oxide powder i) has a mean particle diameter of more than 300 nm and ii) is present in a proportion of from 80 to 98% by weight, based on the total amount of the slip, and c) the solids content, as the sum of aluminium oxide and zirconium dioxide, is from 50 to 85% by weight, based on the total amount of the slip.
摘要:
A method for producing ultra-high purity, optical quality, glass articles is disclosed which involves: 1. compacting metaloxide or metal loidoxide to granules having a mean particle size of less than about 1 millimeter; 2. optionally fully sintering the granules to produce high purity, artificial sand; 3. casting the granulesar artificial sand by conventional techniques, such as, slip casting, to form a high density, porous, green body; 4. optionally drying and partially sintering the green body; 5. optionally fully sintering the green body under vacuum, and 6. optionally hot isostatic pressing the fully sintered green body whereby the metal oxide or metalloid oxides is a pyrogenic silicon dioxide powder with a BET surface area of 30 to 90 m2/g, a DBP index of 80 or less, a mean aggregate area of less than 25000 nm2 and a mean aggregate circumference of less than 1000 nm, wherein at least 70% of the aggregates have a circumference of less than 1300 nm or a high-purity pyrogenically prepared silicon dioxide having metal contents of less than 0.2 μg/g.
摘要:
Process for the preparation of a binder-free metal oxide sol, comprising the steps: a) initial introduction into a vessel of a metal oxide dispersion, wherein the metal oxide powder in the dispersion has an average, number-related aggregate diameter of less than 200 nm, and b1) addition of a metal alcoholate M(OR)x, and optionally of a hydrolysis catalyst, or b2) addition of a starting sol which is obtained by hydrolysis of a metal alcoholate M(OR)x with a hydrolysis catalyst, and the weight-related ratio of metal oxide from the hydrolysis to metal oxide in the dispersion is 0.01 to 1. Metal oxide sol obtainable by this process. Coated substrate which can be produced by means of the metal oxide sol, and shaped article.
摘要:
A process for making gluconic acid and its alkali metal salts by oxidizing glucose with oxygen or oxygen containing gas in an aqueous alkaline solution in the presence of an activated charcoal supported catalyst containing a platinum group metal component, e.g. platinum and palladium and bismuth wherein the platinum, palladium and bismuth are simultaneously deposited on the charcoal support.
摘要:
The use of hitherto known supported catalysts in chlorination processes and oxychlorination processes leads to high pressure drops and to the formation of hot spot temperatures in the reactor. When honeycomb monolithic catalyst supports provided with a multiplicity of channels open at both ends and parallel to the longitudinal axis are used, both the heat dissipation is improved and the pressure drops across the reactor are lowered drastically. This leads ultimately to an increase in the selectivity of the reaction and to a minimization of the combustion rate.
摘要:
Molded articles based on pyrogenically prepared silicon dioxide and having the following physical-chemical characteristic data:______________________________________ External diameter 2 to 15 mm BET surface area 50 to 400 m.sup.2 /g Total Pore volume 0.6 to 1.3 ml/g Crushing strength 40 to 120 N Pore size distribution no pores 95% by weight of SiO.sub.2 remainder Al.sub.2 O.sub.3. ______________________________________ These products are produced by compacting pyrogenically prepared silicon dioxide with kaolin and/or graphite, sugar, starch, urea or wax with addition of water, drying the mixture at a temperature of from 80.degree. to 120.degree. C. and comminuting it to form a powder, pressing the powder to form the desired article, and tempering the articles at a temperature of from 400.degree. to 1200.degree. C. for a period of 0.5 to 6 hours. The molded bodies can be used as a catalyst support or catalyst.
摘要:
Alcohols and/or aliphatic ethers are converted to hydrocarbons employing catalysts consisting of crystalline aluminum silicate, a compound of zinc and/or cadmium and additional silica. The catalyst is produced by treating a crystalline aluminum silicate, in a given case, partially or completely converted into the hydrogen form with a zinc or cadmium compound and shaping with a silica containing binder.
摘要:
A catalyst for the production of hydrocarbon consists essentially of crystalline aluminum silicate, at least one compound of the metal zinc and/or cadmium and additionally silica. The catalyst is produced by heating a crystalline aluminum silicate, in a given case partially or completely converted to the hydrogen form, with a zinc and/or cadmium compound and molding with a silica containing binder.
摘要:
A binder-free metal oxide dispersion with a content of metal oxide of greater than 15 wt. %, wherein the metal oxide powder in the dispersion has a number-average aggregate diameter of less than 200 nm and the dispersion comprises as the liquid phase a mixture of water and a water-miscible, organic solvent. Coated substrates and mouldings produced with the metal oxide dispersion.