Process for the preparation of an oxide, especially a transition metal oxide
AssigneeRhone-Poulenc Chimie
InventorsJean-Claude Grenier, Jean-Pierre Doumerc, Stephane Petit
Life of this patent
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Abstract
A method for preparing an oxide (P), which includes the steps of (i) forming a solid phase compound (O) based on an oxide containing molecular entities (1) chosen from optionally substituted ammonium, diammonium, diazan-ium or diazandium, the entities being distributed within the solid matrix, and (ii) eliminating the entities (1) from the solid phase compound (O) by reacting the solid phase compound (O) with a gaseous stream containing a break-down reactant for the entities (1), and isolating the resulting solid material (P).
Claims21
A method for preparing an oxide (P), said method comprising the steps of:
- (i) forming a solid compound (O) which comprises an oxide and one or more molecular entities selected from the group consisting of substituted or non-substituted ammoniums, diammoniums, diazaniums and diazanediums, said molecular entities being distributed within a lattice of the solid compound (O);
- (ii) reacting said solid compound (O) in solid phase with a gas stream comprising a nitrogen oxide to remove said molecular entities from the solid compound (O) and form an oxide (P);
- and
- (iii) isolating said oxide (P).
A method for preparing an oxide (P), said method comprising the steps of:
- (i) forming a solid compound (O) which comprises an oxide and one or more molecular entities selected from the group consisting of substituted or non-substituted ammoniums, diammoniums, diazaniums and diazanediums, said solid compound (O) containing an element (E) having a number of different oxidation states, said molecular entities being in free space inside a crystal lattice unit of said solid compound (O),
- (ii) reacting said solid compound (O) in solid phase with a gas stream comprising a nitrogen oxide to remove said molecular entities from the solid compound (O) and form an oxide (P);
- and
- (iii) isolating said oxide (P).
A method for preparing tungsten oxide, said method comprising the steps of:
- (i) contacting ammonium paratungstate ((NH.sub.4).sub.10 W.sub.12 O.sub.41.5H.sub.2 O) with a reducing agent to obtain an intermediate tungsten oxide of formula (2):
- (NH.sub.4).sub.x WO.sub.3
- wherein x is a real number from 0.06 to 0.33;
- (ii) reacting the intermediate tungsten oxide of formula (2) in solid phase with a stream of gaseous nitrogen dioxide at a temperature of 15.degree. to 500.degree. C. to obtain a tungsten oxide solid;
- and
- (iii) isolating said solid tungsten oxide.
A method for preparing tungsten oxide, said method comprising the steps of:
- (i) contacting ammonium paratungstate ((NH.sub.4).sub.10 W.sub.12 O.sub.41.5H.sub.2 O) with gaseous hydrogen to obtain an intermediate tungsten oxide of formula (2):
- (NH.sub.4).sub.x WO.sub.3
- wherein x is a real number from 0.11 to 0.15;
- (ii) reacting the intermediate tungsten oxide of formula (2) in solid phase with a stream of gaseous nitrogen dioxide at a temperature of 100.degree. to 400.degree. C. to obtain a tungsten oxide solid;
- and
- (iii) isolating said tungsten oxide solid.
A method for preparing vanadium oxide, said method comprising the steps of:
- (i) contacting vanadic anhydride (V.sub.2 O.sub.5) with a reducing agent and an ammonium halide to obtain an intermediate vanadium oxide of formula (3):
- (NH.sub.4).sub.2 V.sub.3 O.sub.8
- (ii) reacting said intermediate vanadium oxide of formula (3) in solid phase with a stream of gaseous nitrogen dioxide at a temperature of between 15.degree. and 500.degree. C. to obtain a vanadium oxide solid;
- and
- (iii) isolating the vanadium oxide solid.
A method for preparing vanadium oxide, said method comprising the steps of:
- (i) contacting vanadic anhydride (V.sub.2 O.sub.5) with a reducing agent selected from zinc and an alkali metal borohydride, and an ammonium halide to obtain an intermediate vanadium oxide of formula (3):
- (NH.sub.4).sub.2 V.sub.3 O.sub.8
- (ii) reacting said intermediate vanadium oxide of formula (3) in solid phase with a stream of gaseous nitrogen dioxide at a temperature of between 15.degree. and 500.degree. C. to obtain a vanadium oxide solid;
- and
- (iii) isolating the vanadium oxide solid.
A tungsten oxide of formula WO.sub.3, having an hexagonal symmetry and a crystal lattice constant a of between 14.5 and 14.8 .ANG. and a crystal lattice constant c of between 7.6 and 7.8 .ANG..
A vanadium oxide of formula V.sub.2 O.sub.5, which is amorphous and at least partially hydrated.
Dependencies are inferred from the claim text.