A p-type oxide which is amorphous and is represented by the following compositional formula: xAO.yCu.sub.2O where x denotes a proportion by mole of AO and y denotes a proportion by mole of Cu.sub.2O and x and y satisfy the following expressions: 0x<100 and x+y=100, and A is any one of Mg, Ca, Sr and Ba, or a mixture containing at least one selected from the group consisting of Mg, Ca, Sr and Ba.

A p-type oxide which is amorphous and is represented by the following compositional formula: xAO.yCu.sub.2O where x denotes a proportion by mole of AO and y denotes a proportion by mole of Cu.sub.2O and x and y satisfy the following expressions: 0x<100 and x+y=100, and A is any one of Mg, Ca, Sr and Ba, or a mixture containing at least one selected from the group consisting of Mg, Ca, Sr and Ba.

Provided are a method of preparing a metal oxide-silica composite aerogel which includes preparing a silicate solution by dissolving water glass at a concentration of 0.125 M to 3.0 M, after adding and mixing a metal salt solution having a metal ion concentration of 0.125 M to 3.0 M to the silicate solution, precipitating metal oxide-silica composite precipitates by adjusting a pH of a resulting mixture to be in a range of 3 to 9, and separating and drying the metal oxide-silica composite precipitates, wherein the metal salt solution includes a magnesium (Mg)-containing metal salt in an amount such that an amount of magnesium ions is greater than 50 mol % based on a total mole of metal ions in the metal salt solution, and a metal oxide-silica composite aerogel having low tap density and high specific surface area prepared by the method.

Provided are a method of preparing a metal oxide-silica composite aerogel which includes preparing a silicate solution by dissolving water glass at a concentration of 0.125 M to 3.0 M, after adding and mixing a metal salt solution having a metal ion concentration of 0.125 M to 3.0 M to the silicate solution, precipitating metal oxide-silica composite precipitates by adjusting a pH of a resulting mixture to be in a range of 3 to 9, and separating and drying the metal oxide-silica composite precipitates, wherein the metal salt solution includes a magnesium (Mg)-containing metal salt in an amount such that an amount of magnesium ions is greater than 50 mol % based on a total mole of metal ions in the metal salt solution, and a metal oxide-silica composite aerogel having low tap density and high specific surface area prepared by the method.

A process for producing a highly calcined and uniformly calcined product from a feedstock. The process comprising the steps of grinding the feedstock to powder, preheating the powder, and calcining the powder in a reactor plant that comprises a number of reactor segments in which a flash calciner is used in each progressive reactor segment to incrementally react the powder by raising the temperature in each segment. The last segment may be a high-temperature reactor that has a controlled residence time and temperature that may allow controlled finishing of the calcination process to achieve a desired degree of calcination and sintering of the product; and cooling of the product.

A process for producing a highly calcined and uniformly calcined product from a feedstock. The process comprising the steps of grinding the feedstock to powder, preheating the powder, and calcining the powder in a reactor plant that comprises a number of reactor segments in which a flash calciner is used in each progressive reactor segment to incrementally react the powder by raising the temperature in each segment. The last segment may be a high-temperature reactor that has a controlled residence time and temperature that may allow controlled finishing of the calcination process to achieve a desired degree of calcination and sintering of the product; and cooling of the product.

Digestion of impure alumina with sulfuric acid dissolves all constituents except silica. Resulting sulfates, produced from contaminants in the impure alumina, remain in solution at approximately 90 C. Hot filtration separates silica. Solution flow over metallic iron reduces ferric sulfate to ferrous sulfate. Controlled ammonia addition promotes hydrolysis and precipitation of hydrated titania from titanyl sulfate that is removed by filtration. Addition of ammonium sulfate forms ferrous ammonium sulfate and ammonium aluminum sulfate solutions. Alum is preferentially separated by crystallization. Addition of ammonium bicarbonate to ammonium alum solution precipitates ammonium aluminum carbonate which may be heated to produce alumina, ammonia, and carbon dioxide. The remaining iron rich liquor also contains magnesium sulfate. Addition of oxalic acid generates insoluble ferrous oxalate which is thermally decomposed to ferrous oxide. Carbon monoxide reduces the ferrous oxide to metallic iron. Further oxalic acid addition precipitates magnesium oxalate which is thermally decomposed to magnesium oxide.

Digestion of impure alumina with sulfuric acid dissolves all constituents except silica. Resulting sulfates, produced from contaminants in the impure alumina, remain in solution at approximately 90 C. Hot filtration separates silica. Solution flow over metallic iron reduces ferric sulfate to ferrous sulfate. Controlled ammonia addition promotes hydrolysis and precipitation of hydrated titania from titanyl sulfate that is removed by filtration. Addition of ammonium sulfate forms ferrous ammonium sulfate and ammonium aluminum sulfate solutions. Alum is preferentially separated by crystallization. Addition of ammonium bicarbonate to ammonium alum solution precipitates ammonium aluminum carbonate which may be heated to produce alumina, ammonia, and carbon dioxide. The remaining iron rich liquor also contains magnesium sulfate. Addition of oxalic acid generates insoluble ferrous oxalate which is thermally decomposed to ferrous oxide. Carbon monoxide reduces the ferrous oxide to metallic iron. Further oxalic acid addition precipitates magnesium oxalate which is thermally decomposed to magnesium oxide.

This invention relates to a mixed metal oxides adsorbent which comprises: a) an oxide of a first metal which is selected from a metal in oxidation state +1, a metal in oxidation state +2, and mixtures thereof; and b) an oxide of a second metal which is selected from a metal in oxidation state +3, a metal in oxidation state of +4, and mixtures thereof; wherein at least one of the first metal or the second metal comprises a transition metal selected from Fe, Co, Ni, Cu, and mixtures thereof.

The invention pertains to a method for providing a succinic acid solution, comprising the steps of providing a first magnesium succinate containing medium with a magnesium succinate concentration of 18-23 wt. % to a first acidification reactor where it is contacted with hydrogen chloride to form a solution of succinic acid, magnesium chloride and hydrogen chloride, providing a second magnesium succinate containing medium with a magnesium succinate concentration of 25-50 wt. %, and contacting it in a second acidification reactor with the solution of succinic acid, magnesium chloride and hydrogen chloride withdrawn from the first acidification reactor, to form an aqueous mixture comprising magnesium chloride and succinic acid with a succinic acid concentration of at least 18 wt. %. The method according to the invention makes it possible to obtain a solution comprising succinic acid and magnesium 20 chloride with an increased succinic acid concentration.