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1. US20080305025 - Methods for Production of Metal Oxide Nano Particles, and Nano Particles and Preparations Produced Thereby

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Claims

1- 57. (canceled)
58. A method for the formation of small-size metal oxide particles, comprising the steps of:
a) preparing a starting aqueous solution comprising at least one of metallic ion and complexes thereof, at a concentration of at least 0.1% w/w of said metal component;
b) preparing a modifying aqueous solution having a temperature greater than 50° C.;
c) contacting the modifying aqueous solution with the starting aqueous solution in a continuous mode in a mixing chamber to form a modified system;
d) removing the modified system from the mixing chamber in a plug-flow mode; wherein said method is characterized in that:
i) the residence time in the mixing chamber is less than about 5 minutes; and
ii) there are formed particles or aggregates thereof, wherein the majority of the particles formed are between about 2 nm and about 500 nm in size and optionally further calcining said formed particles at a temperature in a range between about 90° C. and about 900° C. to form dehydrated particles
59. A method according to claim 58, wherein the conditions in said system are adjusted by at least one of the steps of:
a) heating said starting aqueous solution by at least 10° C.,
b) elevating the pH of said starting aqueous solution by at least 0.2 units; and
c) diluting the starting aqueous solution by at least 20% or a combination thereof wherein said modified system is maintained at said adjusting conditions for at least 0.5 minutes.
60. A method according to claim 59, wherein said adjustment of conditions is carried out for a period of less than 2 hours.
61. A method according to claim 58, further characterized in that the majority of the formed particles have a degree of crystallinity of more than 50%.
62. A method according to claim 58, further characterized in that the size ratio between the smallest and largest particle of the mean 50% by weigh of the formed particles is less than about 10
63. A method according to claim 58, wherein said dehydrating step and said adjusting step are conducted simultaneously and wherein adjusting involves heating to the temperature of the calcination.
64. A method according to claim 58, wherein said metal is selected from the group consisting of tin, aluminum, silicon, zinc, cobalt, copper, nickel, magnesium, yttrium, vanadium, manganese, cadmium, zirconium, palladium, molybdenum, chromium ruthenium and a combination thereof and , wherein said metal oxide is selected from the group consisting of metal oxides of the formula Metal xO y, metal hydroxy-oxides of the formula Metal p(OH) qO r, metallic acid, various hydration forms of those and compositions wherein those are major components, wherein x, y, p, q, r are each whole integers.
65. A method according to claim 58, wherein the metal concentration in the prepared solution is greater than about 5 wt %
66. A method according to claim 58, wherein said starting solution is treated by at least one of the following operations: a) ultrasound, and b) microwaving.
67. Metal oxide particles whenever formed according to the method of claim 58, products of their conversion and preparations comprising them.
68. The metal oxide particles of claim 67, characterized in at least one of
i. that the purity of the metal oxide particles with regard to other metals intermixed therewith is of at least 95%; and
ii. that said particles are doped with atoms of other compounds.
69. A preparation according to claim 67, wherein said particles are dispersed in a liquid, supported on a solid compound, agglomerated to larger particles, partially fused, coated or any combination thereof.
70. A method comprising using at least one of said particles and said preparations according to claim 67 as at least one of a pigment, a catalyst and a coating.
71. Industrial production of particles according to claim 58, wherein particles are formed at a rate of at least 50 Kg/hour.
72. A method according to claim 58, wherein the temperature of the modifying solution is in the range between 100° C. and 300° C.
73. A method according to claim 58, wherein the modified system is retained for a duration of between 1 and 30 minutes and wherein during said retaining the temperature is maintained within less than a 20° C. change in either direction from the temperature of the modified system.
74. A method according to claim 58, where the residence time in the mixing chamber is less than about 5 seconds.
75. A method according to claim 58, wherein the removed modified system and optionally also a metal salt solution, is introduced into a crystallizer, the temperature of which is kept in the range of 100-300° C.
76. A method according to claim 58, wherein a reagent selected from the group consisting of a dispersant and a basic compound is present in at least one step of a group consisting of preparing, maintaining, adjusting, crystallizing in said crystallizer, flowing in said plug-flow mode, wherein said dispersant is selected from a group consisting of cationic polymers, anionic polymers, nonionic polymers, surfactants, and mixtures thereof and wherein said method further comprises the step of changing the amount of said dispersant.