JPS59333A - Catalyst for preparing pyridine bases - Google Patents

Abstract

PURPOSE:To provide a catalyst for preparing pyridine bases from aldehydes and ammonia, obtained by supporting Ru, Rh, Pt or the like in a specific ratio by a silica alumina carrier. CONSTITUTION:Silica alumina having a composition consisting of 5-30wt% Al2O3 and 95-70wt% SiO2 is used as a carrier and one kind or more of Ru, Rh and Pt is supported in a sum amount of 0.01-5wt% relative to silica alumina to obtain a catalyst for preparing pyridine bases from aldehydes and ammonia. By using this catalyst, the yield of pyridine bases is enhanced. This catalyst is relatively is low in the lowering of activity with the elapse of time and, in the regeneration thereof when the activity thereof is lowered, catalytic activity is easily restored by treatment at a temp. about 100 deg.C lower than the treating temp. of other catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides pyridine bases 1! from aldehydes and ammonia. :! Il! It is related to catalysts for the production of

By using the catalyst of the present invention, pyridine bases can be produced with good yield, and the regeneration treatment of the used catalyst can be carried out easily and at low temperatures.

The pyridine bases produced using the catalyst of the present invention include pyridine and its homologs α-1β- and r-picoline, lutidine, and collidine. For industrial raw materials, etc., picoline is used as a solvent, synthetic resin, vulcanization accelerator raw material, etc., and lutidine is used as a solvent,
It is widely used as a raw material for organic synthesis of medicines.

Conventionally, it has been known to produce all of the above pyridine bases by reacting -S or two or more aldehydes such as formaldehyde, acetaldehyde, acrolein or crotonaldehyde with ammonia in the presence of a catalyst in a high temperature gas phase. be. And as a catalyst for these reactions, silica,
It is also known that alumina, silica alumina, etc. are effective, and silica alumina is particularly excellent. Furthermore, many improved inventions have been proposed in which silica alumina supports metal oxides, chlorides, etc. However, according to the knowledge of the present inventors, the yield of the above-mentioned pyridine or alkylpyridine from these aldehydes is not necessarily high, and the activity of the catalyst in use decreases extremely rapidly, requiring frequent regeneration treatment. There is considerable room for improvement in catalyst performance.

For example, according to Japanese Patent Publication No. 46-41546, acrolein and ammonia are reacted at 420°C using a catalyst made by adding manganese fluoride to silica alumina, and 20% of pyridine and 4.4.8% of β-picoline are reacted. Total 64.8
The yields are as follows: In Japanese Patent Publication No. 51-44946, 71 tsuka alumina (by reacting at 450° C. using a catalyst containing ammonium fluoride and ammonium iodide 17A) is converted into bi1) y f 17.0'Sr, β-picoline-< A total of 46.2 alb was obtained at each yield of 63.2*O. Moreover, considering the fact that expensive acrolein is used as a raw material, it cannot be said that the yields of these target products are economically sufficiently high.

As an example of other aldehyde reaction raw materials,
Citing Publication No. 3394, 71 Tsuka uses a catalyst containing cadmium sulfate added to alumina, formaldehyde,
Acetaldehyde and ammonia were reacted at a total temperature of 440°C to obtain a total yield of 1.5% for pyridine and 6,3% for α-vicolin, 57.8% in total. Although the yield of pyridine is high in this example, it cannot be said that the total yield with picone is high.

Another problem with the catalysts used in these reactions is that their oral activity declines more or less rapidly, which is generally very rapid, so that reactions and regenerations are generally repeated frequently. The cause of the decrease in activity is mainly due to the deposition of carbonaceous matter on the catalyst. Strictly speaking, it is a condensed metal of aldehydes and ammonia, but hereafter it will be abbreviated as carbonaceous.

Therefore, regeneration is performed by passing oxygen-containing gas at high temperature to burn off carbonaceous matter. The problem is that the rate of activity decline is so high that regeneration must be repeated frequently.

For this reason, improvements have been made to extend the service life, and for example, Japanese Patent Application Laid-Open No. 56-26546 states that by molding silica-alumina with a small apparent specific gravity and using the material as a catalyst, the decrease in activity can be alleviated. In this case, the apparent specific gravity is 0.8
Using silica alumina as a catalyst, acrolein and ammonia were reacted at 450°C, and viridi 7f 22.0%
, β-picoline was obtained with a total yield of 49.4% and 71.4%, but after 6t and 10 hours, the yield was 19.0%, 49.5%, respectively.
-There is one.

A method of carrying out this reaction in the presence of oxygen gas is also known.

For example, in Japanese Patent Publication No. 46-6056, 5% by weight of calcium oxide supported on silica alumina is used as a catalyst.
A mixed gas of acrolein, ammonia, air and nitrogen was passed through at 400°C, pyridine i 27.9%, β-picoline f 6.8%. %, with a total yield of 34.7%. Pyridine'fr64.4% and β-picolyph'r were prepared under the same conditions using a catalyst in which zirconium oxide was supported on silica alumina treated with hydrogen fluoride as described in Japanese Patent Publication No. 46-8305.
: 6.9% (obtained from D station rate.

As can be seen from these examples, when oxygen gas coexists, the product tends to have less picoline and more pyridine.

If all the raw materials are acrolein, the main products are pyridine and β-picoline, and the production of r-picoline in ati is generally small.

The present inventors have searched for a catalyst for pyridine and picoline k (8) which has a higher yield than acrolein and ammonia cara. We have found a catalyst that can be obtained with high yield.Also, the decrease in activity of this catalyst is relatively small, and surprisingly, we have found that the temperature during regeneration treatment can be lowered to a temperature much lower than usual. As a result, the present invention has been completed.

That is, the present invention provides a catalyst for producing pyridine bases from aldehydes and ammonia, the catalyst comprising silica alumina and one or more metals selected from ruthenium, rhodium, and platinum. The present invention provides a catalyst for producing pyridine bases supported on silica alumina in an amount of 0.01 to 5% by weight.

Using the catalyst of the present invention, acrolei/carapyridine and β-picoline can be obtained in a total yield of about 86%, and the pyridine yield at this time is 35%, which is higher than ever before under similar conditions. . Further, the catalyst of the present invention is characterized in that when used in these reactions, its activity decreases relatively little over time, and the catalyst that has decreased can be easily regenerated. To regenerate a general silica-alumina-based catalyst, air is passed through it at high temperature to completely burn off the carbon, but the temperature for this is 4.
It is necessary to set the temperature to about 80° to 550°C.

If the temperature is lower than this, the combustion of carbonaceous material will be insufficient and it will not be possible to remove it completely, and if it exceeds about 600℃, the activity will deteriorate due to sintering of the catalyst, so it is necessary to control it within the above range. Regeneration operations are performed by controlling the air supply amount and concentration. In comparison, the carbonaceous combustion of the catalyst of the present invention is effective at a low temperature of about 100°C, which is close to the reaction temperature for pyridine base synthesis. Regeneration is possible by switching the feed gas to air'1fcFi oxygen-containing gas at the reaction temperature.

In other words, the operation of raising and cooling the reactor temperature each time a reaction and regeneration is performed, and its accompanying equipment, are unnecessary.

In the catalyst of the present invention, silica alumina prepared by a conventional method and having an alumina content of 5 to 30% by weight and a silica content of 95 to 70% by weight is used as a carrier.

A large amount of acid is preferable, and an acid having an acidity of 0.1 milliequivalent or more, preferably 0.3 milliJ equivalent or more per duram is suitable. There is no particular upper limit to the acidity, but it is generally about 0.8 to 1.2 milliequivalents/gram. The acidity mentioned here can be determined by amine titration.

The above-mentioned silica alumina can be produced by, for example, gel mixing method, co-gluing method,
It is obtained by preparing it by any method such as an impregnation method and firing it at a temperature range of 200 to 800°C, preferably 400 to 600°C.

A commonly used method can be used to support ruthenium, rhodium, and platinum on the silica alumina. For example, silica alumina may be molded into the desired shape and then mixed into a gel-like material during the production of silica alumina, or it may be mixed into a fired silica alumina fine powder. A method of holding them together and then molding may be used. If the silica alumina has been calcined and is at 'fC, the water-soluble compound of the metal to be supported can be made into a solution, and the silica alumina can be immersed and supported by adsorption, or it can be supported by evaporation to dryness or ion exchange. I can do it.

However, since the metal supported here is expensive, it is necessary to take measures to uniformly disperse it throughout the silica-alumina particles as described below.

That is, a more preferable method among the above-mentioned supporting methods is to support by ion exchange method. According to this method, since the metal to be supported is effectively dispersed, it is economical because only a small amount can be used, and excellent results can be obtained in terms of reaction. For supporting by ion exchange method, all proton acid sites of silica alumina may be exchanged with metal ions to be supported or complex ions of the metal, and a method commonly used for this type of metal is used. For example, the method described in "Catalyst tiM]fR Chemistry 2" (edited by Kusa Ozaki, published by Kodansha, 1980), pages 73 and 241, can be used. According to this method, first silica alumina '4o is added to specified ammonia water at 1: ~
After 2 weeks of immersion, the surface proton acid sites were treated with ammonium salt (-
NH4). For ammine complexes of metals to be completely exchanged, such as platinum (Pt (NHa)43
After ion exchange with an aqueous solution, washing with water, drying, and calcining in the air to decompose the ammine complex, followed by hydrogen reduction, a highly dispersed silica alumina fully supported on shavings can be obtained. In this case, the concentration of ammonia water is generally 0.05~
After soaking for 1 to 15 days using 2N, it is packed into a silica-alumina T-column and the entire ammine complex solution is passed through for exchange, or it is immersed in the solution batchwise to exchange a predetermined amount. Firing at 300-600℃, hydrogen reduction at 200-600℃
Each treatment may be carried out at 500° C. for 1 to 10 hours. '1
Since the fc-supported metal is stable in the metal form under the temperature conditions used in the reaction for producing pyridine bases, one or both of the calcination and reduction steps are omitted and the reactor is filled, and air, ammonia gas, etc. are used as a pre-reaction treatment. It is also possible to carry out decomposition and reduction by circulating all the gases.

The supported metal used in the catalyst of the present invention is -S or two or more metals in a total amount of 0.0% relative to silica alumina.
It is carried in an amount of 1 to 5% by weight, preferably 0.05 to 3% by weight.

If the amount is less than this lower limit, the effect of the present invention will not be manifested, and if it is used more than the upper limit, the selectivity of the reaction will be completely reduced and the cost of the catalyst will be disadvantageous. Therefore, the above-mentioned preparation method that provides the most excellent effect should be used for supporting the metal, but the metal may be selected by the practitioner from the above-mentioned range in consideration of the effect and catalyst cost If.

Since there are no particular restrictions on the VC used in the catalyst of the present invention, the usual conditions for this type of reaction can be applied as is. As aldehydes, formaldehyde, acetaldehyde, acrolein, crotonaldehyde, etc. can be used in one volume.Since the total mole of aldehyde is 5 to 5 times the total mole of ammonia, it is mixed in the gas phase, and 300~
It may be heated to 500° C. and passed through the catalyst of the present invention for a contact time of 1 to 20 seconds. In this case, the raw material gas may be diluted with nitrogen, water vapor, -carbon oxide, carbon dioxide, etc., and the coexistence of a small amount of hydrocarbon gas is not harmful.

Due to raw material supply issues and other reasons, the catalyst of the present invention may not be used in reactions where air is present instead of oxygen gas. The catalyst of the present invention is also effective in reactions that use a mixture of meth, ethanol, acetone, methylal, methyl ethyl ketone, etc. as part of the raw materials.

When the catalyst of the present invention is used in a reaction and its activity decreases and it becomes necessary to regenerate it, the inside of the reaction system is purged with an inert gas such as nitrogen or steam, and then the oxygen-containing gas is heated at 350 to 450°C. The activity is restored by burning and removing the carbonaceous material that has flowed and deposited on the catalyst layer. If the temperature is within the above temperature range, when oxygen gas is supplied, the carbonaceous material starts to burn in the catalyst of the present invention, and the temperature of the catalyst increases. At this time, if the temperature of the catalyst suddenly rises or reaches a high temperature of 600° C. or higher, the catalyst may be completely deteriorated, so rapid supply of oxygen gas should be avoided. For this reason, the oxygen yield in the supplied gas is initially lowered, for example, by diluting air with an inert gas such as nitrogen or steam, or by limiting the amount of oxygen supplied and gradually burning it. is preferred. Judgment as to whether regeneration is complete is made by the disappearance of heat generation under conditions where sufficient oxygen is supplied, or by the disappearance of carbon dioxide generation in the outlet gas, but more complete regeneration is required. If desired, further increase the catalyst layer temperature by an appropriate method.
This is confirmed by the substantial absence of carbon dioxide production in the exit gas at 50C.

The present invention will be explained in more detail with reference to Examples below.

The definition of yield is based on the following formula.

Examples 1 to 3 (Catalyst Preparation Example) Silica alumina (alumina 13
Weight%, Silica 87% by weight, 8 Volatile Chemical: X-638L
) 'I pre-fired in a Matsufuru furnace f 600 c for 3 hours,
The 132 f was immersed in two volumes of 0.2N ammonia aqueous solution and left for two days with occasional stirring. After separating this solution, it was washed with distilled water until no NH4 ions were detected in the washing solution, the water was drained, and it was dried at room temperature for 2 days. Divide this silica alumina into four equal parts, put the pieces in a beaker, add enough distilled water to soak the particles, and place in a hot water bath at 60°C. An aqueous solution of ammine complex was added dropwise and stirred occasionally. After controlling the predetermined It, the mixture was kept at the same temperature for 2 hours with occasional stirring, and further left at room temperature for 2 days. The silica-alumina catalyst precursor supported by metal ammine complex ion exchange was washed with sonic distilled water until no Ci- ions were detected, and then dried at 110°C. This was subjected to a reduction treatment at 400° C. for 4 hours while flowing a total hydrogen gas to obtain each of the catalyst layers listed in Table 1.

Table-1 Examples 4 to 6 (Production example of pyridine bases) Inner diameter i 9m
A stainless steel reaction tube with a length of 3 mm and 3 mm was filled with the catalyst 25 obtained in Examples 1 to 3, and heated through a nighter bath. Acrolein 6% as raw material gas
, ammonia 5%, nitrogen 89% mixed gas total space velocity 3
00 hr' (based on 0°C), and the reaction temperature was 300 hr'.
The reaction was carried out at ~400°C for 5 hours.

The reaction tube outlet gas was cooled to 5 to 10°C and separated into gas and liquid, each of which was analyzed using gas chromatography.

As a result of the reaction, the total yield of pyridine and β-picoline was the highest at a reaction temperature of 400°C, as shown in Table 2, and fc. After the reaction was completed, the reactor was purged with elementary gas, cooled, and the catalyst was taken out.Differential thermal analysis (abbreviated as DTA) was conducted to measure the combustion characteristics of the deposited carbon.

1) Sample of TA analysis conditions 1O da atmosphere Air 50 wl/ml n Heating rate 10°C/min Temperature Room temperature ~800c The combustion peak temperature and amount of weight loss due to combustion for each catalyst are shown in Table-2.

Table 2 Comparative Example 1 The silica alumina used in Examples 1 to 3, which does not support metal, was used in the reaction in the same manner as Examples 4 to 6. After the reaction, analysis of the product and D of the catalyst after reaction in the same manner as in Examples 4 to 6.
TA? Il-I went. The results are shown in Table-3.

Comparative Examples 2-3 Zinc or magnesium nitrate was used as the metal. Zinc nitrate aqueous solution or magnesium nitrate aqueous solution was used in Examples 1-3 using the same ion exchange method as in Examples 1-3. Weight i%, 1.0
Reactions and analyzes similar to those in Examples 4 to 6 were carried out using catalysts loaded in weight ft % and calcined in air at 500 c for 3 hours. The results are shown in Table-3. Pyridine yield tli2
The combustion temperature was as low as 2 to 25% and rose to over 500C in all cases.

(Leaving space below) Table 3 Example 7 and Comparative Example 4 Examples 4 to 4 except that the catalysts used in Example 3 and Comparative Example 1 were used, the reaction temperature was kept at 400°C, and the reaction time was 8 hours. The entire reaction was carried out in the same manner as in 6. During this time, the product was analyzed four times. The results are shown in Table-4.

After the reaction was completed, nitrogen was purged at 400°C, and the catalyst used in Example 3 (abbreviated as Pt/5in2・A) 203) was heated to 400°C, and the catalyst used in Comparative Example 1, (8i0z
- 1 tOs per person) was heated to 500° C. and air was circulated for regeneration treatment.

Air was first diluted with nitrogen gas and supplied at a concentration of 10%, and the concentration was gradually increased to 100% after 3 hours.

I analyzed this intermittent log gas, but P102 and Aj20
In case 3, COz was generated, and in S iOz JkjzOa, COz and CO were generated.

After 1 hour with 100% air, the amount of CO2 and CO produced in both cases decreased to a negligible level, so I tried raising the temperature f by 50℃, but the production of CO2 and CO did not increase, indicating that the combustion of carbonaceous material was considered completed.

The results of using both catalysts in the reaction are also shown in Table 4. In both cases, is the yield of the second reaction, and it can be seen that it has been regenerated, but Pt/5i02 ・AjO Company 8
It was regenerated at 400° C., which is io0° C. lower than that of ioz.Aj203, and this temperature was the same as the reaction temperature.

(Margin below) Table-4 Patent applicant: Mitsubishi Yuka Co., Ltd. Agent: Patent Attorney Hidetoshi Furukawa Agent: Patent Attorney Masahisa Nagatani

Claims (1)

[Claims] (1) A catalyst for producing pyridine bases from aldehydes and ammonia, the catalyst comprising silica alumina and one or more metals selected from ruthenium, rhodium and platinum, the total of which is silica alumina. Against 0. A catalyst for producing pyridine bases, which supports 1 to 5 wk% of O.