JPS5855816B2 - Catalyst manufacturing method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing a catalyst.

To be more specific, in the invention, the catalyst constituent element compounds are alumina, silica-alumina, alumina-magnesia, silica,
The present invention relates to a method for producing a catalyst, which comprises efficiently reducing a catalyst supported on a refractory, porous inorganic carrier such as titanium oxide, or formed by molding a catalyst constituent element compound and an inorganic carrier.

More specifically, the present invention relates to a method for efficiently (reducing) a catalyst constituent element compound supported or molded as described above with an alkali metal borohydride in an aqueous medium containing a polyoxyethylene nonionic surfactant. It is something.

Gas phase methods have conventionally been used to reduce catalyst constituent element compounds, such as reduction under heating using hydrogen gas or hydrogen-nitrogen gas, while liquid phase methods have used formalin, formic acid, hydrazine, and aqueous media of alkali metal borohydrides. A method of immersing it in liquid is known.

Although the gas phase reduction method is widely used industrially, it requires relatively large equipment and requires a heat source for processing at high temperatures, which is not only economically disadvantageous but also dangerous and requires careful handling. It has the disadvantage that it does not.

In the liquid phase method, methods using formalin, formic acid, and hydrazine have problems in reducing ability, require treatment of harmful gases, and have drawbacks such as easy corrosion of the equipment.

In this respect, the method of using alkali metal borohydride as a reducing agent does not generate harmful gases,
It is attracting attention as a method with relatively good reducing ability.

However, when the catalyst is actually reduced using only this aqueous medium of alkali metal borohydride, hydrogen gas (MBH4 + 2H20 → 4H2 + MBO2 (M-alkali metal)) is generated by the reaction of the following formula, but the reaction between this generated hydrogen gas and the catalyst is The contact efficiency is poor and the alkali metal borohydride must be used in an amount several times to several tens of times the theoretical reduction equivalent.

The present invention is a method aimed at overcoming the aforementioned drawbacks of using alkali metal borohydrides as reducing agents.

That is, for example, the case of a catalyst supporting a catalyst constituent element compound will be explained in detail.

An aqueous medium containing a catalyst constituent element compound (hereinafter referred to as a catalyst substance) and a polyethylene nonionic surfactant is mixed with a fire-resistant, porous inorganic material such as alumina, silica-alumina, alumina-magnesia, silica, titanium oxide, etc. The polyethylene nonionic surfactant is supported on a carrier as it is or is dried at 200° C. or lower to contain the undecomposed polyethylene nonionic surfactant in the catalyst material supporting composition. The catalyst substance in the supported composition is reduced by immersion in an aqueous metal borohydride solution.

At this time, due to the foaming property of the polyoxyethylene nonionic surfactant that coexists with the catalyst material, hydrogen gas generated from the alkali metal borohydride is maintained in the bubbles of the polyoxyethylene nonionic surfactant. In order to
The contact time between the hydrogen gas and the catalyst components is increased, and therefore the contact efficiency is improved, resulting in sufficient reduction with a much smaller amount of alkali metal borohydride than without polyoxyethylene nonionic surfactants. It was found that the effect was recognized.

It is preferable that the reduced catalyst is drained and then washed with water to remove the polyoxyethylene nonionic surfactant along with the alkali content.

After washing with water, drying is performed to obtain the finished catalyst, but drying is usually done at 80%
Perform at ~250°C.

Depending on the case, it may be further calcined at a temperature of 600° C. or lower, but it is usually better to use the above drying treatment, particularly at a temperature of 200° C. or lower, and use it as it is as a finished catalyst.

Next, in the case of a shaped catalyst, a polyoxyethylene nonionic surfactant is dissolved in a powdered carrier, a powdered or liquid catalyst material, and the required amount of water.* If necessary, a shaping aid is added. , for example, by adding alumina sol or silica sol,
After thorough mixing, it is molded using a granulator such as an extrusion molding machine, and after drying, it is subjected to a reduction treatment in an aqueous medium of alkali metal borohydride as in the case of supported catalysts, washed with water, and dried to obtain a finished catalyst, or , adding a powdered carrier, a powdered or liquid catalyst material, and the required amount of water or a molding aid if necessary,
After thorough mixing, the molded catalyst was molded, dried and calcined in the same manner as above, impregnated with a polyoxyethylene nonionic surfactant, dried, reduced with an aqueous alkali metal borohydride solution, washed with water and dried to obtain the finished catalyst. shall be.

In the above examples of use of polyoxyethylene nonionic surfactants, they are all contained in the catalyst composition, but the nonionic surfactant is used in an aqueous medium containing an alkali metal borohydride as a reducing agent. Even if it is contained in a liquid, its effect is exhibited.

The polyoxyethylene nonionic surfactant used in the present invention needs to have foaming properties as described above, and therefore needs to have an average molecular weight of 500 or more, preferably 1000 or more.

The amount of the nonionic surfactant used is usually 0.1 to 5 M', preferably 0.2 to 20 g per carrier 11.

Examples of polyoxyethylene nonionic surfactants include the following.

Polyethylene glycol HO(CH2CH20)nH(
n=11-900), polyoxyethylene glycol alkyl ether RO(CH2CH20)nH (R is an alkyl group having 6 to 30 carbon atoms, n-3 to 120), polyoxyethylene-polyoxypropylene-polyoxyethylene Krikor x1+x2 +x3 +x4+y1
+y2+y3+y4 = 20-800), polyoxyethylene alkyl aryl (alkyl group having 6-12 carbon atoms, n = 3-120)1. l-”lioxyethylene alkyl ester R-COO(C2H40)nH or R COO(C2H40)n-□-CH2CH2COO-R
(R is an alkyl group having 6 to 24 carbon atoms, and n=3 to 12
0), the alkyl group of polyoxyethylene alkyl amine 30, n, nl and n2 are 3 to 120), the alkyl group of polyoxyethylene alkyl amide 30, n, nl and n2 are 3 to 120), poly Fatty acid ester of oxyethylene sorbitan (R is an alkyl group having 6 to 24 carbon atoms, and n is 3 to 60
) The alkali metal borohydride used in the present invention is
The alkali metals are compounds of sodium, potassium, lithium and ammonium.

The amount used varies depending on the form of the compound of the catalyst substance to be treated, but for example, if the catalyst substance to be treated is a chloride or hydroxide, it is 0.5 mol or more, preferably 2 mol or more, per 1 mol of the catalyst substance. It is more than a mole.

The amount of the aqueous medium of alkali metal borohydride is at least 1 times the pore volume of the catalyst, preferably 1.2 to 4 times the pore volume of the catalyst.
As a processing device, a so-called rotating drum having a structure in which rotation can be stopped freely is used, and a catalyst substance and an aqueous medium liquid of a reducing agent are placed in this drum device and mixed while rotating.
In terms of contact efficiency, it is preferable to perform the reduction treatment while foaming the polyoxyethylene nonionic surfactant.

In addition, the pH and temperature of the aqueous medium of alkali metal borohydride must be on the alkaline side in order to effectively carry out the reduction, preferably high pH, and the temperature must be at room temperature or lower. It is desirable that

As catalyst materials used in the present invention, noble metal compounds such as platinum, palladium, rhodium, iridium, and ruthenium are most suitable for the purpose, but cobalt, nickel, copper, iron, chromium, silver, gold, cadmium, germanium, etc. Examples include those consisting of a single or mixed system of inorganic element compounds such as , tin, and selenium.

The catalyst produced by the method of the present invention is a catalyst for purification by oxidation or reduction of carbon monoxide (CO), hydrocarbons (HC'), nitrogen oxides (NOx), etc. in general industrial waste gas, and a catalyst for purifying carbon monoxide (CO), hydrocarbons (HC'), nitrogen oxides (NOx), etc. in general industrial waste gas, and in automobile exhaust gas. It is useful as a purification catalyst by oxidation or reduction of CO1HC, NOx, etc., a hydrogenation catalyst, an oxidation catalyst for organic synthesis, a reforming catalyst, etc.

The present invention will be explained in more detail below with reference to Examples, but it goes without saying that the present invention is not limited thereto.

Example 1 A polyethylene cylindrical container with an inner diameter of 125 mm and a length of 185 mm with one circular part open, the open part facing up and the bottom facing down, with the cylindrical part tilted 30 degrees from the horizontal, and rotated in this state. In a stop-free catalyst impregnation device, a cylindrical activated alumina with an average diameter of 3 mm, an average length of 5 mm, a pore volume of 0.66 cc/@, a surface area of 110 m/f and a bulk specific gravity of 0.66 f/cc was first prepared. I put 200cc in it.

On the other hand, pluronic propylene oxide (PO) with an average molecular weight of 8500, ethylene i (
EO), the weight of EO in the whole molecule is 8.
0.41% of polymeric nonionic surfactant was added.

The impregnating device containing the activated alumina was set at a rotation speed of 20 times per minute, and while rotating the device,
The aqueous solution was added, and then from a position approximately 5 CrIL from the carrier, 10 mV/min of 201
It was dried by blowing hot air at 0'C.

Approximately 20 minutes after blowing hot air, the surface of the carrier was almost dry, so rotation was stopped, the carrier was taken out, and dried at 150° C. for about 3 hours.

Next, 150 cc of 25°C aqueous solution containing 34 m9 of sodium borohydride (Na BH4) was prepared in the impregnating apparatus, and the dried support was introduced into this solution at a rate of 1 min.
Reduction treatment was performed for 30 minutes while rotating at 0 rotations.

During this reduction, hydrogen was generated and the supported composition was enveloped in fine bubbles as the reduction was carried out.

The reduced support was washed with water and dried again at 150°C for 3 hours,
A finished catalyst was obtained.

Note that the amount of NaBH4 used is a value equivalent to five times the reduction equivalent.

Comparative Example 1 A catalyst-supported dry composition was obtained in the same manner as in Example 1 without using a polymeric nonionic surfactant.

Next, the catalyst was reduced in the same manner as in Example 1 using an aqueous solution containing 102 m9 of sodium borohydride, washed with water and dried to obtain a completed catalyst.

Note that the amount of NaBH4 used is a value equivalent to 15 times the reduction equivalent.

Example 2 A catalyst impregnation device similar to Example 1 was equipped with a pore volume of 0.66 CC/P and a surface area of 95 m''/P with an average diameter of 3.3 mm.
S', spherical activated alumina 20 with bulk specific gravity 0.669/CC
I put 0CC.

On the other hand, to 80 cc of an aqueous solution containing chloroplatinic acid corresponding to 0.16P as platinum, a block copolymer of tetronic nitrogen-containing propylene oxide (PO) and ethylene oxide (EO) with an average molecular weight of 19,000 was added to all molecules. A catalyst-supported dry composition was obtained in the same manner as in Example 1 by adding 0.8z of a polymeric nonionic surfactant containing 70% by weight of EO.

The catalyst was then reduced in the same manner as in Example 1 using 120 cc of an aqueous solution containing 110 ml of sodium borohydride, washed with water, and dried to obtain a finished catalyst.

Note that the amount of NaBH used is a value equivalent to seven times the reduction equivalent.

Example 3 A dry catalyst-supported composition was obtained in the same manner as in Example 2 without the use of a molecular nonionic surfactant. Then, in the same manner as in Example 2, 155 μ of sodium borohydride and Example 2 were prepared. The catalyst was reduced using an aqueous solution containing the same polymeric nonionic surfactant used in , washed with water, and dried to obtain a finished catalyst.

Note that the amount of NaBH4 used is a value equivalent to 10 times the reduction equivalent.

Comparative Example 2 A catalyst-supported dry composition was obtained in the same manner as in Example 2 without using a polymeric nonionic surfactant.

Next, the catalyst was reduced in the same manner as in Example 2 using a washing solution containing only 233 m9 of sodium borohydride, washed with water, and dried to obtain a finished catalyst.

The amount of NaBH4 used was a value equivalent to 15 times the reduction equivalent.

Example 4 A catalyst impregnation apparatus similar to Example 1 was used with an average diameter of 3 and a pore volume of 0.49 cc/I? , and the surface area is 145 m/
′? , bulk specific gravity 0.74? 200 cc of spherical activated alumina was added.

On the other hand, polyoxyethylene rubitan monolaurate with an average molecular weight of 1100 was added to 90 CC of an aqueous solution containing palladium nitrate corresponding to 0.2 f as palladium and 0.21 nitric acid, and the number of moles of ethylene oxide added in the total molecules was 17. Example 1 by adding 0.4S' of a nonionic surfactant (trade name, Emazol 1130, Kao Atlas Co., Ltd.)
A catalyst-supported composition was obtained in the same manner as described above.

Next, it was reduced using a 120 CC aqueous solution containing 1.27 P sodium borohydride in the same manner as in Example 1, washed with water for 1 hour, and then dried in the same manner as in Example 1 to obtain a finished catalyst.

Note that the amount of N a B H used is a value equivalent to seven times the reduction equivalent.

Comparative Example 3 A catalyst-supported dry composition was obtained in the same manner as in Example 4 without using a polymeric nonionic surfactant.

Next, the catalyst was reduced in the same manner as in Example 4 using 120 cc of an aqueous solution containing 1.82P sodium borohydride, washed with water, and dried to obtain a finished catalyst.

Note that the amount of Na BH used is a value equivalent to 10 times the reduction equivalent.

Example 5 The catalysts obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were subjected to the following initial low temperature activity performance test.

In this test, a 250C catalyst was packed into a stainless steel reaction tube with an inner diameter of 26 peaks, and the catalyst bed was preheated to 120C using nitrogen gas.
7500 p prns Oxygen (02) 2.5% by volume, Carbon dioxide (CO2) 10% by volume, Nitric oxide (NO) 1
000 ppm, water vapor 10% by volume, remaining nitrogen (N2)
Preheat the mixed gas in an electric furnace and heat it at 5V24000h.
r' (STP) to increase the inlet temperature by 40°C per minute, and the outflow gas was chopped.For propylene, a continuous flame ion current method (FID method) hydrocarbon analyzer, C
O was measured and analyzed using a non-dispersive infrared analyzer (NDIR method).

The obtained results were adjusted to 50% and 9% for HC and CO, respectively.
The figures are summarized in inlet temperature (°C) at 0% purification rate.

It was found that compared to the examples, the catalysts of the comparative examples had higher purification temperatures, and were inferior in low-temperature activity, despite using a large amount of NaBH4.

Example 6 The following initial activity test was conducted on the catalysts obtained in Examples 1 to 4 and Comparative Examples 1 to 3.

In this test, a 12CC sample was filled into a stainless steel reaction tube with an inner diameter of 18mm, CO was 1% by volume, and propane was 500p.
A mixed gas consisting of 2% by volume of pJ02, 10% by volume of water vapor, and the remainder nitrogen was introduced at a space velocity of 50,000 hr' (STP) at a gas inlet temperature of 300°C to 450°C,
Each measurement temperature (set value) was maintained for 5 to 15 minutes to obtain a steady state, and the outflow gas at that point was analyzed for HC and CO using an analyzer similar to Example 5.

The results are shown in Table 2. The numbers in the table are
It shows the purification rate (%) of HC and Co.

The catalysts of the comparative examples are all inferior in HC activity compared to the examples.

Example 7 Catalysts obtained in the same manner as in Example 1 and Comparative Example 1 were subjected to a low-temperature activity test using engine exhaust gas.

The test was conducted by filling a down-flow type catalytic converter with catalyst 1.81 and installing it 1.2 m from the manifold outlet of a bench engine.
By adjusting the negative pressure and rotation speed of the engine, CO
2% by volume, HCl 600-1800ppm (methane equivalent), 024% by volume, space velocity 28000hr-1 (ST
By switching the valve, the engine exhaust gas at a constant inlet temperature of 280 to 290°C is passed through the catalytic converter for 11 hours and changes in the concentration of the outflow gas are measured for CO, HC, CO2, etc. The measurements were recorded using a Horiba MEXA-18 analyzer.

The obtained results are summarized in terms of the time (seconds) required to reach a 50% purification rate for each of HC and Co.

Similar to the results of Example 5, it is recognized that the catalyst of the present invention is superior to the catalyst of the comparative example in the actual gas test.

Example 8 The catalysts obtained in Example 2.3 and Comparative Example 2 were tested for purification activity in an exhaust gas purification device of a phthalic anhydride production plant.

In this test, 130 cc of catalyst was packed into a stainless steel reaction tube with a diameter of 53 mm, and the temperature was set to be raised sequentially from 170 to 270 ℃ by electric heating, and the space velocity was set to 350 ℃.
The purification performance is determined based on the odor of the exhaust gas coming out of the catalyst layer at 00 hr' (STP).

As a result, the catalyst according to the present invention has a gas inlet temperature of 230°C.
In accordance with the fact that the catalyst of Comparative Example 2 showed good purification performance to the extent that no odor was felt in the exhaust gas, the catalyst of Comparative Example 2 was heated at 260°C.
Finally, the purification performance was such that the odor could not be detected.

Example 9 1 kg of finely powdered titanium oxide was chopped, 300 cc of silica sol containing 20% silica was added as a binder,
Mix thoroughly using a kneader, extrude using an extruder, dry at 150°C for 3 hours, and then sinter in air at 600°C for 3 hours to produce a titanium oxide carrier with a diameter of 3 mm and an average length of 5 mm. did.

This carrier has a bulk specific gravity of 1 g/cc and a pore volume of 0.2 cc/cc.
f, surface area 15 rri'/? Met.

200 CC of this support was placed in the same catalyst impregnation apparatus as in Example 1, and on the other hand, a Pluronic PO, EO block copolymer having an average molecular weight of 11,000 was added to 80 CC of an aqueous solution containing chloroplatinic acid equivalent to 0.2 S' as platinum. , a polymeric nonionic surfactant with an EO weight of 80% in the total molecule 0.2
A catalyst-supported dry composition was obtained in the same manner as in Example 1 except that P was added.

Next, in the same manner as in Example 1, the catalyst was reduced using a 150 CC aqueous solution containing 140 m9 of sodium borohydride, washed with water, and dried to obtain a finished catalyst.

Note that the amount of NaBH4 used is a value equivalent to seven times the reduction equivalent.

Comparative Example 4 A catalyst-supported dry composition was obtained in the same manner as in Example 9 without using a polymeric nonionic surfactant.

Next, the catalyst was reduced in the same manner as in Example 9 using an aqueous solution containing 292 ml of sodium borohydride, washed with water, and dried to obtain a finished catalyst.

Note that the amount of NaBH4 used is a value equivalent to 15 times the reduction equivalent.

Example 10 The catalysts obtained in Example 9 and Comparative Example 4 were subjected to the following nitrogen oxide reduction test.

In this test, 15 cc of catalyst was packed in a stainless steel reaction tube with an inner diameter of 18 mm, and 200 ppm of nitrogen monoxide (NO), 200 ppm of NH3, and 0
) A mixed gas consisting of 4% by volume, 10% by volume of water vapor, and the remainder nitrogen was introduced at a gas inlet temperature of 200'C to 250°C and a space velocity of 20,000hr' (STP), and a steady state was obtained at each measurement temperature. The effluent gas at that point was measured and analyzed for NO using the Chemilumi method.

The results obtained regarding the NO purification rate (%) are summarized.

Example 11 Finely powdered nickel nitrate 111g and chromic anhydride 2
30y is finely powdered activated alumina 775 with an average particle size of 50μ.
After mixing well, alumina sol 400S' containing 10% alumina was added and thoroughly kneaded with a kneader.

This was molded using an extrusion molding machine, dried at 100°C, and further baked in air at 500°C for 3 hours to give a diameter of 3 mm1.
It was made into a beret with an average length of 6 mm.

The composition ratio was such that the atomic ratio of nickel to chromium was 1:6, and the total weight of nickel oxide and chromium oxide was 20% by weight.

200 CC of these pellets were placed in the same catalyst impregnating apparatus as in Example 1, and on the other hand, an aqueous solution 8 containing palladium nitrate corresponding to 0.11% of palladium and nitric acid of 0.11%.
Palladium nitrate was supported in the same manner as in Example 1 by adding 0.41 g of the same polymeric nonionic surfactant used in Example 9 into OCC.

Next, in the same manner as in Example 1, the catalyst was reduced using a 120 CC aqueous solution containing 3.27 f of sodium borohydride, washed with water, and dried to obtain a finished catalyst.

The amount of NaBH4 used is equivalent to three times the reducing equivalent.

This catalyst was charged into a reactor connected to an exhaust fan installed at the draft outlet, and a combustion test was performed on waste gas from an enameled wire burning furnace.

The average combustible concentration in this waste gas is naphtha 870 ppm,
It contained 1240 ppm of cresol and 1100 ppm of phenol.

This enameled wire baking furnace waste gas is heated at 350℃ and at a space velocity of 20
As a result of passing through the catalyst layer for 000 hr' (STP), the concentration of each component in the treated gas was at a trace level.

The above analysis of harmful components was conducted using a gas chromatograph.

Claims (1)

[Claims] 1. A method for producing a catalyst, which comprises reducing a catalyst constituent element compound with an alkali metal borohydride in an aqueous medium of a polyoxyethylene nonionic surfactant.