Patent GB-166285-A (GB)
Title: Catalysts and processes of making them
IPC: B01J21/00
Filed: 1920-01-07
Abstract: Metal-oxide catalysts for oxidation processes are prepared by precipitating the hydrated oxide in as fine a state of subdivision as possible, and then drying and driving out all or a part of the water of hydration at a temperature not exceeding 250 DEG  C. or, in a current of free-oxygen-containing gas, at a temperature not exceeding 200 DEG  C.  The process is applicable to the oxides of the metals-manganese, cobalt, copper, iron, nickel, bismuth, lead, and silver.  As a general rule a mixture is more active than the single oxides, or the single oxides may be made more active by the addition of a finely divided platinum group metal.  In examples, a manganese dioxide catalyst is prepared by adding oxalic acid to a solution of permanganic acid to precipitate the dioxide which is filtered off, washed, and dried at or below 200 DEG  C.; alternatively, powdered potassium permanganate is added to a mixture of anhydrous manganese sulphate and sulphuric acid, the mixture poured into water, the precipitate collected, washed, and dried at 200 DEG  C.; copper oxide catalyst by precipitating a concentrated copper salt solution with concentrated sodium hydroxide or carbonate solution, collecting the precipitate, washing, and drying at 120 DEG  C.; cobalt oxide catalyst by adding a solution containing sodium hydroxide and hypochlorite to a concentrated cobalt salt solution, and the resulting precipitate collected, washed, and dried at 200 DEG  C.; a mixed manganese-silver-oxide catalyst by suspennding the paste of the first example in a solution of silver nitrate precipitating with sodium hydroxide, collecting the precipitate, washing, and drying first on a water bath and then in an oil bath at 130 DEG  C.; or the mixed oxides may be prepared by simultaneous precipitation or by intimate admixture of the already formed hydrated oxides, and subsequent drying under the specified conditions.  After filtering and before drying the material may be pressed into cakes, which in some cases form agglomerates during drying, and may be subsequently broken up into lumps or granules.  Oxide catalysts so prepared are active at considerably lower temperatures than those thought to be heretofore necessary, and their activity can be still further increased by drying in a gas containing free oxygen or by heating in such gas, after drying as specified, to a temperature of 100-200 DEG C.  By the employment of these catalysts the following substances may be oxidized at ordinary or slightly raised temperatures,-carbon monoxide, ammonia, sulphur dioxide, aldehydes, alcohol, and toluene. Specification 13687/14 is referred to.ALSO:Aldehydes, alcohol, and toluene are oxidized in the presence of free oxygen and at ordinary or slightly raised temperature by the employment of a metal-oxide catalyst prepared by precipitating the hydrated oxide in as fine a state of subdivision as possible, and then drying and driving out all or a part of the water of hydration at a temperature not exceeding 150 DEG  C., or, in a current of free-oxygen containing gas, at a temperature not exceeding 200 DEG  C.  Mixtures of oxides are usually more active than the single oxides, or the activity of the latter may be increased by the addition of finely divided platinum group metal. Specification 13687/14, [Class 1 (i), Chemical processes &c.], is referred to.ALSO:Carbon monoxide is oxidized in the presence of free oxygen, and at ordinary or slightly raised temperature, by the employment of a metal-oxide catalyst prepared by precipitating the hydrated oxide in as fine a state of subdivision as possible, and then drying and driving out all or a part of the water of hydration at a temperature not exceeding 250 DEG  C., or, in a current of free-oxygen containing gas, at a temperature not exceeding 200 DEG C. Mixtures of the oxides are usually more active than the single oxides, and the activity of the latter may be increased by the addition of a finely divided platinum group metal.ALSO:Metal oxides are prepared in a form suitable as catalysts by precipitation of the hydrated oxide in as fine a state of subdivision as possible, and then drying and driving out all or a part of the water of hydration at a temperature not exceeding 250 DEG  C., or, in a current of free-oxygen containing gas, at a temperature exceeding 200 DEG  C. Oxides of the following metals may be prepared in this manner,-manganese, cobalt, copper, iron, nickel, bismuth, lead and silver.  In examples, a manganese-dioxide catalyst is prepared by adding oxalic acid to a solution of permanganic acid to precipitate the dioxide which is filtered off, washed and dried at or below 200 DEG  C.; alternatively, powdered potassium ferromanganate is added to a mixture of anhydrous manganese sulphate and sulphuric acid, the mixture forced into water, the precipitate collected, washed, and dried at 200 DEG  C.; copper oxide catalyst by precipitating a concentrated copper salt solution with concentrated sodium hydroxide or carbonate solution, collecting the precipitate, washing, and drying at 120 DEG  C.; cobalt oxide catalyst by adding a solution containing sodium hydroxide and hypochlorite to a concentrated cobalt salt solution, and the resulting precipitate collected, washed, and dried at 200 DEG  C.; a mixed manganese-silver-oxide catalyst by suspending the paste of the first example in a solution of silver nitrate, precipitating with sodium hydroxide, collecting the precipitate, washing, and drying first on a water bath and then in an oil bath at 130 DEG  C.