JPH01130734A - Production of catalyst containing ruthenium - Google Patents

Abstract

PURPOSE:To prevent evaporation of ruthenium from a catalyst contg. ruthenium by impregnating a carrier with a soln. contg. ruthenium, depositing ruthenium in the form of hydroxide on the carrier thereafter by adding alkali to the impregnated soln., then drying the carrier and calcining the dried carrier. CONSTITUTION:A soln. contg. a nitrate together with ruthenium alone or in combination with another metal as catalyst component is prepd. After impregnating a carrier with said soln. contg. the catalyst component, the catalyst component is transformed to hydroxide by adding alkali to the impregnated soln. and the hydroxide is deposited on the surface of the carrier. The nitric acid radical is removed as a soluble salt by filtration or decantation, if necessary by washing. A ruthenium-contg. catalyst is produced by drying and heating such as calcining, etc., after executing the above described treatment. The metal to be used as another metal is Ni, Co, etc., and preferred amt. of the alkali to be added is an equivalent amt. or a little more.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a ruthenium-containing catalyst using nitric acid or a nitrate. Ruthenium is used alone or in combination with metals such as nickel and cobalt as a catalyst for hydrogenation, especially hydrogenation of carbonyl compounds or aromatic compounds, reduction of nitrogen compounds, Fischer-Tropsch synthesis, etc., and has high activity and excellent properties. Shows selectivity.

In the production of this ruthenium-containing catalyst, nitrates are most commonly used as raw material compounds of metals such as nickel or cobalt due to their economic efficiency, ease of handling, and ease of anion removal during catalysis.

Since ruthenium is easily available, ruthenium trichloride and ruthenium nitrate are used.

(Problems to be Solved by the Invention) In the production of catalysts in which cobalt and ruthenium are supported on a carrier, the present inventors have often experienced that the amount of ruthenium supported is significantly lower than the predetermined amount. Since the amount of ruthenium supported has a large effect on activity and selectivity, we carefully examined the methods and conditions for each catalyst manufacturing process. It has been found that in a catalyst production method in which the metal salt is then thermally decomposed by firing in an air atmosphere and further reduced with hydrogen if necessary, ruthenium is mainly reduced in the drying step and the firing step. It is well known that among ruthenium compounds, Ru○4 is volatile, but it is the most common raw material compound, and the one produced by the oxidation of the trivalent ruthenium salt used by the present inventors. is said to be the most stable oxide. Conventionally, in order to produce Rub4 from Rub, it is thought that ignition in air or the assistance of a strong oxidizing agent is required. was completely unexpected.

(Means for Solving the Problems) The present inventors have made extensive studies to solve the above-mentioned problems and obtain a catalyst manufacturing method with less ruthenium volatilization, and have obtained the following knowledge. That is, in a system where the ruthenium source is ruthenium nitrate or coexists with nitric acid or a nitrate such as cobalt, oxidation of ruthenium to Rub,
Volatilization is caused by the strong oxidizing power of nascent nitrogen oxides produced by thermal decomposition of nitric acid or nitrates; the rate of volatilization depends on temperature and nitrogen oxide concentration, but temperature also affects the decomposition of nitric acid or nitrates. This also affects the drying speed, so even if the drying temperature is lowered, the production of nitrogen oxides will continue for a long time, so the amount of volatilization will not be reduced. It has become clear that volatilization cannot be completely avoided even when the contact time is very short and the nitrogen oxide concentration is diluted by large amounts of drying air.

As a result of intensive studies based on this knowledge, we found that in the production of ruthenium-containing catalysts in which nitrate radicals coexist, a carrier is impregnated with a solution containing the supported components, and then an alkali is added to the impregnated carrier to make the supported components insoluble. The present invention was achieved based on the discovery that a predetermined amount of ruthenium can be supported without volatilizing ruthenium by precipitating it as a hydroxide on a carrier and removing the nitrate radicals by filtration or decanting.

An object of the present invention is to provide a method for producing a ruthenium-containing catalyst that does not volatilize ruthenium, and an object of the present invention is to provide a method for producing a ruthenium-containing catalyst that does not volatilize ruthenium. In the method for manufacturing a ruthenium-containing catalyst, the carrier is impregnated with a solution containing the above-mentioned solution to support the supported component. This can be easily achieved by depositing the nitrate radical on a carrier as a soluble salt, removing the nitrate radical as a soluble salt by filtration or decantation, and if necessary by washing, followed by heat treatment such as calcination.

To explain the present invention in more detail, in the production of a catalyst in which ruthenium is supported alone or together with other metals such as nickel or cobalt on a carrier such as alumina, silica, or activated carbon, the raw material compound of the supported component is nitrate or nitric acid. In a method using a solution, the carrier is immersed or impregnated in a solution containing the supported component, and then an aqueous alkaline solution is added to cause the supported component to precipitate as a hydroxide on the solid support. Since nitrate radicals are present in the solution as soluble salts, they are removed by filtration or decantation. The alkali used here may be selected as appropriate depending on the type of supported component since it may generate undesirable caustic alkali or alkali carbonate.

The amount of alkali added is preferably an equivalent amount or a slightly larger amount. If the amount added is too small, the supported components may elute into the liquid side.If the amount added is too large, excess alkali metal may remain in the catalyst, or a large amount of washing water may be required to remove it, which is undesirable. .

In addition, the concentration of the alkaline aqueous solution is not particularly limited, but l~
3 o wt% is preferred. If the concentration is too high, mixing will be insufficient and complete neutralization will be difficult to achieve, while if the concentration is too low, the amount of liquid will be large and filtration or sifting will take a long time. In the present invention, it is preferable to carry out washing with water after filtration or decantation, which is significant in more completely removing the nitrate radicals remaining in the carrier, and also in removing excess to the extent required by the purpose of the catalyst. It also removes alkali.

The obtained carrier cake containing the supported components is then dried. The drying method can be appropriately selected depending on the shape of the catalyst and the purpose. For example, in the case of a granular catalyst, it is possible to dry it still in a flash dryer, and in the case of a fluidized catalyst, the cake may be mixed with water again to form a slurry, and if necessary, it may be wet-pulverized and then spray-dried. The dried product thus obtained is calcined and, if necessary, reduced to obtain a catalyst on which a predetermined amount of ruthenium is supported.

The present invention will be specifically described below with reference to Examples, but the present invention is not limited to the following Examples unless the gist of the invention is exceeded.

Example-/Ru as II/, 0? A nitric acidic aqueous solution of ruthenium nitrate with a concentration of
me/1iI γ-alumina 200? The entire amount was absorbed while stirring.

Next, the impregnated product was added to 330 ml of ≠wt% aqueous sodium hydroxide solution with stirring to neutralize it.

After continued stirring for 30 minutes, the mixture was filtered and washed to remove sodium nitrate and excess sodium hydroxide. At this time, ruthenium was not detected in the P solution. Next, the filter cake was dried in a flash dryer at 710°C for 10 hours, and then calcined at SOO°C in an air atmosphere to obtain a catalyst. Ruthenium analysis was carried out by introducing the gas during drying and firing into an absorption liquid, but no ruthenium was detected. When the obtained catalyst was analyzed after reduction, it was found that Ru = 2.0/wt%.

Comparative Example-/Similarly to Example-/, after impregnating ruthenium nitrate solution (τγ-alumina), it was immediately dried at 10°C for io hours without being treated with an aqueous sodium hydroxide solution, and then calcined at 500°C. Ruthenium equivalent to 1 g was detected on the side, and ruthenium equivalent to 1 g was detected during firing.

The amount of ruthenium supported on the obtained catalyst was 8j O in the reduced state.
He was in charge of wt.

Example-2 22o as co maintained at 30°C? /
100 rnl of a mixed aqueous solution of cobalt nitrate and ruthenium chloride with a concentration of ≠ r t / t as l sRu
The entire amount was absorbed while stirring with the same γ-alumina 2002 used in Example-/.

Next, the impregnated product was added to 360 trtl of a 10 wt % aqueous sodium hydroxide solution with stirring and maintained for 30 minutes.

At this time, the pH of the solution was 70.2.

Then, sodium nitrate and excess sodium hydroxide were removed by filtration and washing with water. No elution of cobalt or ruthenium into the P solution was observed.

Next, the above filter cake was placed in a flash dryer at 230°C and 110°C.
After drying for a period of time, the catalyst was calcined at SOO° C. in an air atmosphere to obtain a catalyst. No volatilization of ruthenium to the gas side was observed during drying or calcination.0 When the obtained catalyst was analyzed for its composition after reduction, Co=R,
70 wt%, Ru=/, Ri, S' wt%.

Comparative Example-2 22o S'/t as CO maintained at 30'C
As sRu, 100 rnl of a mixed aqueous solution of cobalt nitrate and ruthenium chloride with a concentration of ≠ 2/l was used as γ-alumina 200ml, the same as that used in Example. I stirred it up and sucked it all up.

Next, the impregnated product was dried in a flash dryer at 2 tO"C for 110 hours, and then fired at 100 °C in an air atmosphere. During drying, an amount of ruthenium equivalent to 20% of the charged ruthenium was detected on the gas side. Furthermore, the generation of nitrogen oxides ceased during the drying process, and no volatilization of ruthenium to the gas side was observed during firing.

The resulting catalyst composition is Oo = 7 jwt in the reduced state.
%Ru=/, j j wt%. This amount of Ru supported is 74. Corresponds to r%.

Example-3 3.0 kg of fine-grained γ-alumina obtained by firing pseudo-boehmite gel at tSO°C was mixed with 7.0 kg of water. After mixing with Okg to make an aqueous slurry, it was added to a nitric acid aqueous solution of ruthenium nitrate for 30 k! I (containing Ru = 77?) and an aqueous solution of cobalt nitrate, 70 ky (containing C0 = 7702) were added under stirring. After stirring for 30 minutes,
% sodium hydroxide aqueous solution/3 kg as a slurry, -pH
ruthenium and cobalt hydroxides were deposited on the γ-alumina.

Next, the above slurry was filtered and washed to remove sodium nitrate and excess sodium hydroxide, and then water was added again to form an aqueous slurry, which was milled in a wet grinder until the average particle size of the particles was about 0.
It was pulverized to a particle size of μm.

Next, this slurry is dried in a rotary disc type spray dryer under the conditions of drying air temperature of 200 °C at the inlet and 60 °C at the outlet, and the obtained dried product is heated in a rotary cylindrical furnace under an air atmosphere at ♂O °C.
A catalyst was obtained by firing for 30 minutes. Ruthenium analysis was conducted by introducing exhaust gas during spray drying and firing into an absorption liquid, but no ruthenium was detected.

Comparative Example-3 2 kg of fine-grained γ-alumina obtained by firing pseudo-boehmite gel at tro℃ was mixed with water? , and male were mixed with 1 to form an aqueous slurry, which was then finely pulverized using a wet pulverizer until the average particle size of r-alumina was approximately 0.0 μm.

Next, the slurry after pulverization 10. 30 kg of the same ruthenium nitrate solution used in Example 3 and 70 kg of cobalt nitrate aqueous solution II were added to the same solution under stirring. 30
After stirring for a minute, spray drying and baking were performed in the same manner as in Example-3. Ruthenium equivalent to 6.6% of the charge in the gas side during drying, and ruthenium in the dry product during firing/
Ruthenium equivalent to 0% was detected. The catalyst composition after reduction in Example-1 was Co = 20. Owt% Ru =
2.00yt%, whereas in Comparative Example-2
0o=20.0wt%, Ru=Ha♂hirowt%.

(Effects of the Invention) According to the present invention, it is possible to prevent the volatilization of ruthenium during the production of a ruthenium-containing catalyst, and therefore it is possible to stably secure the supported amount for the purpose, and also to prevent the equipment from being sealed due to the toxicity of ruthenium. In addition, there is no need for any abatement equipment.

Claims (1)

[Claims] 1) Production of a ruthenium-containing catalyst that contains a nitrate radical and impregnates a carrier with a solution containing ruthenium alone or ruthenium and other metal components as a supported component to support the supported component. In the method, a carrier is impregnated with the solution, and then an alkali is added to the impregnated carrier to precipitate the supported components as hydroxides on the carrier, and the nitrate radicals are precipitated as soluble salts by filtration or decantation. A method for producing a ruthenium-containing catalyst, which comprises removing the ruthenium by washing and then subjecting it to heat treatment such as drying and calcination. 2) The method according to claim 1, wherein the other metal supported together with ruthenium is cobalt.