| 摘要 |
<p>#CMT# #/CMT# Process for preparing a powder comprises: (a) preparation of a mother liquor comprising (i) an oxide based constituent or a precursor of the base constituent and an additional constituent (A), or (ii) an oxide based constituent or a precursor of the base constituent incorporating an agent; (b) hydrothermal preparation, from the mother liquor, of a soil of which crude particles have a maximum size less than 100 nm; and (c) after optional drying step, washing the soil to obtain a powder comprising more than 99.3 mass% of the base constituent based on dry material. #CMT# : #/CMT# Process for preparing a powder comprises: (a) preparation of a mother liquor comprising (i) an oxide based constituent or a precursor of the base constituent and an additional constituent (A) of formula (MC), where M is an agent comprising oxoanions, anions of the elements of the column 17 of the periodic table elements and/or hydroxide (OH ->), and C is complement, which is inorganic when the agent is OH ->or (ii) an oxide based constituent or a precursor of the base constituent incorporating the agent; (b) hydrothermal preparation, from the mother liquor, of a soil of which crude particles have a maximum size less than 100 nm; and (c) after optional drying step, washing the soil to obtain a powder comprising more than 99.3 mass% of the base constituent based on dry material. An independent claim is included for the powder. #CMT#USE : #/CMT# The powder is useful: to catalyze a reaction comprising selective hydrocarbon conversion reactions including selective oxidation reactions, hydrogenation reactions, dehydrogenation reactions, hydrogenolysis reactions, isomerization reactions, dehydrocyclization reactions, reforming reactions, methane formation reactions and Fischer-Tropsch synthesis reactions (claimed). #CMT#ADVANTAGE : #/CMT# The process is capable of simply preparing the powder with high purity. #CMT#INORGANIC CHEMISTRY : #/CMT# Preferred Process: The step (c) comprises: at least one operation comprising filtration-, a dialysis- and purification by using ion exchange resins- with or without prior re-suspension of soil, rinsing and/or acid-base neutralization (preferred); and mixing in a solvent at a temperature below its boiling temperature at 1 bar for greater than 10 minutes, then filtered. The acid-base neutralization comprises mixing in an aqueous solution having a pH lower or greater than point of zero charge of the base constituent according to the cationic or anionic impurities to be eliminated, maintaining the suspension at a temperature below its boiling temperature at 1 bar for more than 10 minutes, and a filtration. The pH is less than or greater than point of zero charge of at least 4 pH units. In the process, the temperature is maintained for less than 30 minutes. The pH is adjusted by adding hydrochloric acid, nitric acid and/or perchloric acid or by adding ammonia. The rinsing is performed in water having purity at least equal to that of osmosed water or in an alcohol of purity greater than 98 vol.%, for 10-30 minutes. The agent is introduced in the form of an additive made of the agent (M) and the complement (C) comprising group constituted of: positively charged organic molecules of which the organic radical is constituted by a group of atoms comprising carbon, hydrogen, oxygen and/or nitrogen; cations of elements of columns 1 (preferred) and 2; cations of aluminum, manganese, iron, yttrium, copper, silver and cerium; and ammonium. In the step (b), heating the mother liquor in a closed container at a temperature greater than the boiling temperature at 1 bar and at 100-300[deg] C, where the temperature is maintained at least an hour and the speed of temperature rise is less than 250[deg] C/hour. In the process, the parameters are adjusted so that the primary particles of the powder have maximum size greater than 10 nm. The powder particles are doped using a dopant comprising oxoanions, anions of the elements of the column 17 of the periodic table and/or cations of the elements of the column 1 of the table. In the process, the primary powder particles are not coated with catalyst, or after recovery, at least part of the primary particles with a catalyst, when the catalyst is formed by the metals of columns 8, 9 and 10 of the periodic table of elements and having a cubic structure, preferably when the base constituent of support particles is zirconia, for catalyzing a reaction comprising: a reaction where more than 26%, preferably more than 51% of exposed planes (1,0,0) and/or more than 35%, preferably more than 70% of the exposed planes (1,1,1), based on the total exposed surface of the catalyst, are obtained; selective hydrogenation reactions, preferably selective hydrogenation reactions of molecules containing at least one carbonyl function, and selective hydrogenation reactions of molecules containing at least two double bonds; methane formation reactions; and Fischer-Tropsch synthesis reactions. Preferred Components: The powder comprises more than 99.9 mass% of the base constituent, based on dry material. In the step (a), the quantity of agent is greater than 10 ->4>mol/l, preferably 10 ->2>mol/l. The base constituent and/or the precursor of the base constituent comprise more than 99.9 mass% of the base constituent and/or precursor of the base constituent, respectively. The base constituent of the powder has more than 97%, preferably 100% of a monoclinic structure. The base constituent or the precursor of the base constituent added in the mother liquor is an oxide comprising hafnium oxide (HfO 2), zirconium oxide (ZrO 2), molybdenum oxide (MoO 3), tungsten oxide (WO 3) (all preferred), thorium oxide (ThO 2), europium oxide (Eu 2O 3), samarium oxide (Sm 2O 3), magnetite (Fe 3O 4), bismuth oxide (Bi 2O 3), tin oxide (SnO 2), niobium pentoxide (Nb 2O 5) or arsenic oxide (As 2O 3). The agent is sulfate (SO 42>->), phosphate (PO 43>->), hydroxide, carbonate (CO 32>->), fluoride (F ->), chloride (Cl ->), perchlorate (ClO 4->), borate (BO 33>->) and/or nitrate (NO 3->), or is Cl ->, ClO 4->and/or NO 3->, if the pH is less than 4. The pH of the mother liquor is: less than 4, if the base constituent is HfO 2, ZrO 2, ThO 2, Eu 2O 3, Sm 2O 3, Fe 3O 4or Bi 2O 3; less than 2, if the basic constituent is HfO 2, ZrO 2, ThO 2, Eu 2O 3, Sm 2O 3, Fe 3O 4, Bi 2O 3, SnO 2, Nb 2O 5, As 2O 3, MoO 3or WO3; or more than 10. The fabricated powder has a content of impurities such as silicon dioxide (less than 0.1 mass% or 100 ppm), aluminum oxide (less than 0.1 mass% or 100 ppm), magnesium oxide (less than 0.1 mass% or 50 ppm), calcium oxide (less than 0.1 mass% or 100 ppm), sodium oxide (less than 0.1 mass% or 100 ppm), chloride (less than 0.1 mass% or 100 ppm), NO 3->(less than 0.1 mass% or 100 ppm), SO 42>->(less than 0.1 or 100 ppm), iron oxide (50 ppm) and/or titanium dioxide (less than 0.1 mass% or 50 ppm). The dopant is silicates, phosphates, sulfates, chlorides, fluorides, sodium and potassium. #CMT#EXAMPLE : #/CMT# No suitable example given.</p> |
