JPH0838904A - Chromium-based fluorination catalyst, its production and fluorinating method - Google Patents

Abstract

PURPOSE:To obtain a chromium-base fluorination catalyst which is effective for the production of HCFC and HFC and to provide its production method, and to provide a method to efficiently fluorinate hydrocarbon halide by using this catalyst. CONSTITUTION:This catalyst is obtd. by calcining a compd. essentially comprising tervalent chromium hydroxide in the presence of hydrogen at temp. between >=350 deg.C and <=500 deg.C, or the catalyst is obtd. by first heat treating the compd. above described at temp. between >=100 deg.C and <=600 deg.C in an inert gas flow and then calcining the heat treated compd. at temp. above described in the presence of hydrogen, or the obtd. catalyst is further partially fluorinated to obtain the catalyst. Hydrocarbon halide having 1 to 4 C is brought into contact with hydrogen fluoride in a gas phase in the presence of the catalyst above described.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a chromium-based fluorination catalyst,
The production method and the fluorination method, more specifically, a chromium-based fluorination catalyst that can be used in the production of a halogenated hydrocarbon by a gas phase fluorination reaction of a halogenated hydrocarbon having 1 to 4 carbon atoms, a production method thereof, and the catalyst. Relates to a method for fluorinating halogenated hydrocarbons. In particular, it is intended to provide a method for producing a catalyst having high activity and high selectivity, which is effective in producing hydrofluorocarbons (abbreviated as HFC) and hydrochlorofluorocarbons (abbreviated as HCFC) that have recently been mass-produced as alternative CFCs. To aim.

[0002]

2. Description of the Related Art A method for producing a halogenated hydrocarbon containing fluorine from a halogenated hydrocarbon having 1 to 4 carbon atoms and hydrogen fluoride is roughly classified into a gas phase method and a liquid phase method. In recent years, chlorofluorocarbons (CFCs) containing a chlorine atom in the molecule
The problem of ozone layer depletion due to (. Some are.
The vapor phase method is particularly effective as a method for producing these alternative CFCs. In the gas phase method, selection of a catalyst is important, and various catalysts have been proposed so far.

According to the patent, Cu, A supported on activated carbon
g, Na, Cd, Ca, Zn, Hg, V, Sb, Mn,
Various metals such as halides of Fe, Ni, Co and Pt (see US Pat. No. 2005707) are considered to be effective catalysts. However, in general, chromium oxide, fluoride, oxyfluoride or aluminum,
A catalyst containing a halide such as iron as a main component is often used. Among them, chromium oxide is the most common example, and various preparation methods and compositions have been proposed so far.

Japanese Patent Publication No. 39-10310 discloses Cr which is obtained by impregnating alumina with chromic acid (hexavalent), drying, and reducing with hydrogen.
_{A 2} O ₃ catalyst is proposed. In addition, Japanese Patent Publication No.
According to the publication, oxygen firing and hydrogen firing are repeated several times, and finally the oxygen firing has an atomic ratio of O to Cr of 1.5 to
Black chromium oxide in the range of 3 is said to have high activity. Further, Japanese Patent Publication No. 42-3004 discloses a method of preparing a hydrated chromium secondary hydroxide prepared by a precipitation method from a trivalent chromium salt solution in an atmosphere consisting of steam and an inert gas.
A Cr ₂ O ₃ catalyst obtained by calcination at ˜400 ° C. is disclosed.

Recently, a catalyst obtained by a method similar to that in Japanese Patent Publication No. 423004/1993, that is, chromium hydroxide prepared by the precipitation method, has been used in Japanese Unexamined Patent Publication (Kokai) No. 5-146680.
₂ Specific surface area 170 calcined at 380-460 ° C under air flow
It is claimed that chromium oxide of m ² / g or more is highly active. The applicant has already discovered that it is important to select heat treatment conditions during activation regeneration of the Cr-based fluorination catalyst. That is, as described in JP-A-5-92141, the catalyst is first heat-treated with an oxidizing gas such as O ₂ and then with a reducing gas such as H _{2 to} sufficiently activate the catalyst without scattering Cr. Can be recovered.

[0006]

However, when producing HCFC or HFC containing a hydrogen atom in the molecule proposed as an alternative CFC by the reaction of a halogenated hydrocarbon and hydrogen fluoride, the conventional method is used. In many cases, the reaction is less likely to proceed than in CFC production. In such a case, it is necessary to carry out the reaction at a high temperature of 350 ° C. or higher in order to obtain a significant yield with the conventional chromium-based fluorination catalyst. Furthermore, in the production of halogenated hydrocarbons containing hydrogen in the molecule, carbon is strongly attached to the catalyst, and the activity tends to deteriorate rapidly (see JP-A-1-262946).

Since the rate of deterioration increases as the reaction temperature increases, carrying out the reaction at a low temperature using a highly active catalyst not only saves thermal energy but also has a great advantage in terms of catalyst life. There is. Therefore, in order to efficiently produce HCFCs and HFCs, there is a demand for a catalyst having higher activity and longer life than conventional fluorination catalysts.

The main object of the present invention is HCFC, HFC
And a halogen containing a hydrogen atom and a fluorine atom in the molecule by vapor-phase fluorinating a halogenated hydrocarbon having 1 to 4 carbon atoms using the catalyst. It is an object of the present invention to provide a method for efficiently producing a modified hydrocarbon.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that heat treatment conditions at the time of preparation greatly increase the catalyst performance, as experienced during activation and regeneration of the catalyst. It was clarified that it depends on, for example, a compound containing trivalent chromium hydroxide as a main component in the presence of hydrogen in an amount of 35
A chromium-based fluorination catalyst obtained by partially fluorinating a catalyst precursor obtained by calcination at a temperature of 0 ° C. or more and 500 ° C. or less under an air flow containing hydrogen fluoride, etc. It has been found that it is superior to the above fluorination catalyst, and the present invention has been completed.

In the present invention, (1) a raw material containing trivalent chromium hydroxide as a main component in the presence of hydrogen at 350 ° C. or higher and 500 ° C. or higher.
It is a method for producing a chromium-based fluorination catalyst characterized by firing at the following temperature, and includes the following preferred embodiments. (2) A raw material containing trivalent chromium hydroxide as a main component is first heat-treated in an inert gas stream at a temperature of 100 ° C to 600 ° C, and then 350 ° C to 500 ° C in the presence of hydrogen.
A method for producing a chromium-based fluorination catalyst, which comprises firing at the following temperature.

(3) The method for producing a chromium-based fluorination catalyst as described in (1) or (2) above, which comprises partially fluorinating after firing in the presence of hydrogen. (4) Chromium-based fluorination according to the above (3), which is partially fluorinated at a temperature of 300 ° C. or higher and 500 ° C. or lower in a stream containing hydrogen fluoride after firing in the presence of hydrogen. Catalyst manufacturing method.

(5) The raw material whose main component is trivalent chromium hydroxide is at least one selected from the group consisting of cobalt, nickel, copper, silver, zinc, cadmium, mercury, aluminum, gallium, tin and lead. The method for producing a chromium-based fluorination catalyst according to any one of (1) to (4) above, which contains an element. Further, in another aspect, the present invention provides (6) a fluorination catalyst or a precursor produced by the production method of the above (1) (which has a large amount of Cr ₂ O ₃ analogues depending on the additive but has a different crystal structure). And the half width of the diffraction peak of the X-ray diffraction pattern is the same as the above-mentioned raw material obtained by firing at 400 ° C. for 2 hours or more in an atmosphere containing oxygen of 1 vol% or more under atmospheric pressure. Of fluorination catalyst or precursor characterized by being 1.2 times or more of the half width of the diffraction peak corresponding to, and (7) the diffraction peak of crystalline Cr ₂ O _{3 in} the X-ray diffraction diagram. Also provided is a fluorination catalyst characterized by having a half value width of 0.8 ° or more in a peak having a lattice spacing d in the range of 2.65 to 2.69.

[0013] The present invention, in yet another aspect,
(8) Halogenated carbonization characterized by bringing a halogenated hydrocarbon having 1 to 4 carbon atoms into contact with hydrogen fluoride in a gas phase in the presence of the fluorination catalyst according to any one of (1) to (7) above. A method for fluorinating hydrogen, and (9) the method for fluorination according to (8) above, wherein the halogenated hydrocarbon is a hydrogen-containing halogenated hydrocarbon.

The trivalent chromium hydroxide referred to in the present invention is a compound which can be represented by a chemical formula, for example, Cr ₂ O ₃ .nH ₂ O, and is prepared from a trivalent Cr salt by a precipitation method or the like. You can The value of n is usually 2 to 4
Is in the range. Trivalent Cr salts include nitrates, chlorides,
Sulfate is preferably used. Of these, nitrate is particularly preferable. Chromium hydroxide obtained by the precipitation method was prepared by mixing a trivalent Cr salt aqueous solution with an alkaline aqueous solution, filtering and washing the precipitate.
It can be obtained by drying.

When a molded product is desired as the catalyst shape, it can be molded by tableting after drying or by extrusion molding before drying. The drying temperature is preferably 80 to 130 ° C, particularly preferably 90 to 120 ° C. At this time, the value of n is in the range of 2.5 to 3.5.
It is possible to dry at a higher temperature in an inert gas, but it is desirable to keep the drying temperature at 150 ° C. or lower when performing tablet compression molding.

Any alkali can be used as long as it is available on an industrial scale, but ammonia, sodium hydroxide, sodium carbonate, sodium hydrogen carbonate,
Potassium hydroxide, potassium carbonate, potassium hydrogen carbonate, ammonium carbonate, and ammonium hydrogen carbonate are preferable, and ammonia is particularly preferable. The mixing method is C
The pH of the reaction solution is 6.
A method of dropping simultaneously or alternately so as to be in the range of 5 to 9 is particularly preferable.

Before firing the compound containing trivalent chromium hydroxide as a main component in an inert gas before firing in the presence of H ₂ , heat treatment may be performed at a temperature of 600 ° C. or less in advance. It is expected that such a heat treatment causes a dehydration reaction or a decomposition reaction of residual salts, and that chromium hydroxide approaches a compound represented by the composition formula Cr ₂ O ₃ . However, O ₂
Not subjected to heat treatment at 300 ° C. or higher temperature in an atmosphere containing (represents an atmosphere containing here the O ₂ from the atmosphere containing O ₂ at an absolute pressure 1000Pa or more, typically is that in the air ). This is because when chromium hydroxide is exposed to an atmosphere containing O ₂ at a high temperature of 350 ° C. or higher, it is converted into Cr ₂ O ₃ having a small specific surface area, and the once reduced specific surface area is not easily recovered.

A requirement for a highly active catalyst is that it has a large specific surface area, and the fluorination treatment carried out in a later step further lowers the specific surface area. It is disadvantageous to use.
It is desired that the catalyst precursor before fluorination has a specific surface area of 150 m ² / g or more, more preferably 180 m ² / g or more. Therefore, it is preferable to use chromium hydroxide which is exposed to the atmosphere containing O ₂ only at a temperature of 200 ° C. or lower, and further 150 ° C. or lower.

Even if the precursor which has been H ₂ fired once,
_When firing in an atmosphere containing ₂ , the specific surface area is reduced, and further, hexavalent Cr is partially generated, which causes problems such as scattering during fluorination treatment.
Finally, it is necessary to avoid firing in an atmosphere containing O ₂ as in the publication. Therefore, a preferable firing method is to heat the dried raw material containing chromium hydroxide as a main component to a temperature of 350 ° C. or higher and 500 ° C. or lower in a stream containing hydrogen, and then perform firing for a predetermined time, or dry The subsequent raw material containing trivalent chromium hydroxide as a main component is first heat-treated at a temperature of 100 ° C. or higher and 600 ° C. or lower in an inert gas stream, and then 350 in a stream containing hydrogen.
There is a method of firing at a temperature of from ℃ to 500 ℃ for a predetermined time.

The raw material containing chromium hydroxide as a main component is C
It may contain a metal element of r or less, and is particularly expected to be effective as a cocatalyst.
0,11,12,13,14 family (new IUPAC nomenclature)
At least one element selected from the group consisting of elements, among them, Co, Ni, Cu, Ag, Zn, Cd, Hg,
Al, Ga, Sn, Pb, etc. have an atomic ratio to Cr of 0.001 to 0.5, preferably 0.003 to 0.3,
Particularly preferably, when it is contained in the range of 0.003 to 0.2, activity promotion and life prolonging effect can be expected.

To add the above-mentioned elements, a predetermined amount of the salt of the element to be added to the Cr salt aqueous solution when the chromium hydroxide is prepared by the precipitation method, or the salt of the element to be added to the chromium hydroxide is added. It can be easily achieved by a method such as impregnation with an aqueous solution. Therefore, a metal element other than Cr is typically contained as a metal hydroxide or a metal, and therefore, a raw material containing chromium hydroxide as a main component is a mixed hydroxide of Cr and another metal or a mixture of the same with a metal. Can be

The compound as described above is calcined in the presence of H ₂ to obtain a catalyst precursor. Conventionally, it has been considered that the firing atmosphere of the fluorination catalyst is preferably a stream of an inert gas such as N ₂ as in Japanese Patent Publication No. 42-3004 and Japanese Unexamined Patent Publication No. 5-146680. However, when the calcination is carried out in the presence of H ₂ as in the present invention, a catalyst having higher activity can be obtained.

If the firing temperature is too low, there is no effect, and if it is too high, problems such as a decrease in specific surface area occur.
50 to 500 ° C. is suitable, and preferably 370 to 46.
0 ° C., particularly 370 to 450 ° C. is preferable. H ₂ in the firing gas
The concentration can be 0.1 to 100 vol%. If necessary, it is possible to entrain 20 vol% or less of water in the gas, and 0.3 to 10 vol% of water vapor may be entrained in H ₂ . If O ₂ is contained in the gas, it is a safety concern, so the O ₂ concentration should be suppressed to 0.1 vol% or less. Gas flow rate is 10 to 10 in GHSV (standard state conversion)
000 h ^-1 is suitable and the pressure is atmospheric pressure to 10 kg / cm ²
G is convenient for operation. Under these conditions, the precursor is baked for at least 30 minutes, preferably 1 to 10 hours.

It is possible to use the precursor as it is for the reaction, but it is desirable to perform a fluorination treatment before the reaction.
The fluorination may be conveniently carried out in the gas phase, and the precursor may be treated in the presence of a gas having a fluorination ability such as HF, F ₂ or a hydrocarbon containing F in the molecule. Temperature, pressure,
Regarding processing conditions such as processing time, it is necessary to select appropriate conditions for achieving the target fluorine content, depending on the fluorination ability of the gas used.

A preferred fluorination method is a method performed under an air flow containing HF. Processing temperature is 300 ~
The temperature is preferably 500 ° C, particularly preferably 300 to 450 ° C. The HF concentration can be 1 to 100 vol%, but if too much heat is generated during processing, it will have a bad effect such as a large decrease in the specific surface area. To prevent this, if necessary, HF is diluted with an inert gas such as N _{2 to} raise the temperature due to heat generation (hereinafter,
It is preferable to control so that ΔT) is 50 ° C. or less at the maximum.

The gas flow rate is 10 to 10,000 hours in GHSV.
^-1 is suitable. The pressure can be atmospheric pressure to 20 kg / cm ² G. The HF used should have as low a water content as possible, preferably a water content of 15
It is advisable to use HF in an amount of 0 weight ppm or less, more preferably 100 weight ppm or less. As an example of a more preferred method for fluorinating a catalyst precursor, HF and N ₂ are supplied at 300 to 350 ° C. under atmospheric pressure so that the HF concentration is 5 to 30 vol%, and fluorination is started. After the hot spots passed through the precursor packed bed, gradually adjust the HF concentration to 90 while paying attention to heat generation.
Increase until vol% or more. Then increase the pressure 2
It is treated under a pressure of 10 kg / cm ² G until heat generation is stopped.

The heat treatment in an inert gas, the calcination in the presence of H ₂ and the fluorination treatment can be carried out in the same reactor as long as they are made of Inconel or Hastelloy, which is simple in operation. By the HF treatment, the catalyst precursor is partially fluorinated and becomes a compound incorporating F atoms. However, the catalyst must have O in addition to F.
As a preferable content range of each component, O is 3 to 28% by weight and F is 3 to 45% by weight.

Although the reason why the activity is improved by baking in the presence of H ₂ is not clear, it is not possible to use Adv. Catal. Volume 20, 7
According to the description on the page, when chromium hydroxide is fired in N ₂ , the amorphous state is maintained up to about 470 ° C., and conversion into crystalline Cr ₂ O ₃ does not occur. On the other hand, H
_When fired in ₂ , microcrystallization occurs at 390 to 400 ° C., and the presence of H ₂ seems to promote crystallization.

Actually, as shown in the following Examples, when Cr ₂ hydroxide prepared by a precipitation method from chromium nitrate and aqueous ammonia was calcined with N ₂ at 400 ° C., crystalline Cr ₂ O ₃ was not formed. , When crystalline H _{2 was} fired at the same temperature, crystalline Cr ₂ O ₃ (Eskolaite (ICDD card 19
It was confirmed that the powder X-ray diffraction pattern of 1988 version 38-1479) was almost the same). Further, if the catalyst precursor calcined in the N ₂ gas stream or the H ₂ gas stream at the same temperature is subjected to HF treatment under the same conditions, the use of the precursor calcined in the H ₂ gas stream also tends to produce a catalyst having a small F content. Admitted. In this way, the catalyst that partially fluorinated the chromium oxide that has advanced crystallization is more difficult to fluorinate the precursor than the catalyst that partially fluorinated the amorphous chromium oxide,
It is assumed that the activity is high.

Crystallization is also promoted when firing in an atmosphere containing O ₂ , but as is called the glow phenomenon, crystallization rapidly progresses with large heat generation. At this time, the specific surface area is significantly reduced, and the specific surface area of the resulting catalyst precursor is 50 m ² / g or less. However, there is no noticeable heat generation (unless the temperature rises so rapidly) in the presence of H ₂ ,
The specific surface area of the resulting catalyst precursor is as large as that when calcined in a N ₂ stream.

As described above, the requirements for a highly active catalyst (catalyst precursor) are that crystallization has progressed to some extent and that the specific surface area is large. Therefore, the desired catalyst (catalyst precursor) structure can be said to be an aggregate of fine crystals. The characteristics of the catalyst precursor comprising fine crystals of the desired catalyst or catalyst precursor according to the present invention appear to some extent in the powder X-ray diffraction diagram (hereinafter abbreviated as XRD pattern). That is, when the catalyst precursor is chromium oxide, it has crystallized Cr ₂ O ₃ diffraction pattern because it is crystallized,
Since it is a microcrystal, the half-width of the peak (the half-width of the peak here is the true half-width Δ (2θ) derived from the sample excluding the spread of the peak due to the optical system of the apparatus). However, when an additive other than Cr is contained in the order of% or more, crystalline Cr is added depending on the kind of the additive.
_{Since the 2} O ₃ diffraction pattern may not be exhibited, it is difficult to specify the characteristics of the system containing the additive only by the XRD pattern. Further, it is not easy to define the peak full width at half maximum because it depends on the measurement conditions and the measuring device, but the preferable range of the peak half width is at least the same raw material under atmospheric pressure in an O ₂ atmosphere (1 vol% or more). O
It is necessary to have a value of 1.2 times, preferably 1.4 times or more the half value width of the precursor obtained by firing at 400 ° C. for 2 hours or more under an atmosphere containing ₂ ).

An example of a preferable range of the full width at half maximum for the catalyst having a diffraction pattern of crystalline Cr ₂ O ₃ (catalyst precursor) will be described. The lattice spacing d is located in the range of 2.65 to 2.69. Diffraction line (ICDD card 38-1479
It can be defined that the true full width at half maximum (corresponding to the (104) plane) is 0.8 ° or more, more preferably 1.0 ° or more. The full width at half maximum is measured with a device equipped with a monochromator, for example, a scanning speed of 1 ° / min or less and a light receiving slit width of 0.15.
It is desirable to perform the measurement under the condition that a high angular resolution such as mm or less can be obtained.Moreover, the spread of the diffraction line due to the optical system of the device can be measured under the same condition with a single crystal such as silicon having a sufficiently large crystallite size. It needs to be corrected.

The fluorination catalyst of the present invention can be applied when fluorinating a halogenated hydrocarbon having 1 to 4 carbon atoms with HF. Among them, the reaction is difficult to proceed with the conventional fluorination catalyst, and it is particularly effective for the fluorination of the hydrogen-containing halogenated hydrocarbon which is extremely fast in catalyst deterioration. The hydrogen-containing halogenated hydrocarbon referred to in the present invention is a halogenated hydrocarbon containing H in the molecule, and one example is CH.
Cl ₃ , CH ₂ Cl ₂ , CH ₂ FCl, CH ₃ Cl, C
₂ HCl ₃ , C ₂ H ₂ Cl ₂ , C ₂ H ₃ Cl, C ₂ HC
l ₅ , C ₂ HFCl ₄ , C ₂ HF ₂ Cl ₃ , C ₂ HF ₃
Cl ₂ , C ₂ HF ₄ Cl, C ₂ H ₂ Cl ₄ , C ₂ H ₂ F
Cl ₃ , C ₂ H ₂ F ₂ Cl ₂ , C ₂ H ₂ F ₃ Cl, C ₂
H ₃ Cl ₃ , C ₂ H ₃ FCl ₂ , C ₂ H ₃ F ₂ Cl, C
₂ H ₄ Cl ₂ , C ₂ H ₄ FCl, C ₂ H ₅ Cl, C ₃ H
₂ F ₄ Cl ₂ , C ₃ HF ₄ Cl ₃ and the like. further,
All or part of Cl in the above hydrocarbons may be Br or I
It may be a compound substituted with.

Fluorination of hydrogen-containing halogenated hydrocarbons typically involves two or more stages of fluorination when the hydrogen-containing halogenated hydrocarbon contains unsaturated groups. For example, fluorine of CCl ₂ = CHCl proceeds as in the following formula. (1) CCl ₂ = CHCl + 3HF → CF ₃ CH ₂ Cl
+ 2HCl (2) CF ₃ CH ₂ Cl + HF → CF ₃ CH ₂ F + HCl That is, in the first step, the addition reaction of HF to the unsaturated group and the substitution reaction of chlorine to fluorine occur, and in the second step, only the substitution reaction. Occurs.

Replacing the final chlorine with fluorine is particularly difficult. In the above example, CCl ₂ = CHCl
(HCC-1120) from CF ₃ CH ₂ Cl (HCFC
First fluorination reaction to -133A) takes place relatively easily but, from _{HCFC-133a CF 3 CH 2 F} (HF
The second or final stage fluorination reaction to C-134a) is difficult.

The chromium-based fluorination catalyst of the present invention is effective for both of the above-mentioned fluorination reactions, but the conventional fluorination catalyst is difficult to fluorinate in the second stage. The fluorination catalyst is particularly effective and useful for the above-mentioned second stage fluorination. When these hydrogen-containing halogenated hydrocarbons are fluorinated with HF, the target compound can be obtained in a higher yield than conventional fluorination catalysts. further,
A certain yield is obtained at a low reaction temperature, resulting in a longer catalyst life being achieved.

Especially, there is no danger of depleting the ozone layer recently.
CH attracting attention as an alternative CFC₂F₂(HFC-
32) and CH₂FCF₃(HFC-134a), CHF
₂CF₃Synthesis route for producing (HFC-125)
CH considered as₂Cl ₂, CH₂FCl, CHC
l = CCl₂(Trichlorethylene), CF₃CH₂C
l (HCFC-133a), CCl₂= CCl₂(Par
Chloroethylene), CF₃CHCl₂(HCFC-12
3), CF₃CHFCl (HCFC-124) fluorine
It is particularly effective for the chemical reaction.

The fluorination reaction may be carried out by a reaction method such as a fixed bed, a fluidized bed or a moving bed, but a fixed bed is generally used. The reaction conditions may vary depending on the reaction, but generally, the molar ratio of HF to halogenated hydrocarbon is 0.5.
~ 20, temperature: 200-400 ° C, pressure: atmospheric pressure ~ 20
kg / cm ² G (gauge pressure), SV: 50 to 100000h
^-1 .

[0039]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but it goes without saying that the present invention is not limited by such description. In the description, the composition of the catalyst represents the weight% of each element contained in the catalyst obtained by chemical analysis, and the molar ratio in the reaction example represents the molar ratio of HF to halogenated hydrocarbon. SV is a value converted into a standard state, and pressure is a gauge pressure. The container (Catalyst Preparation Example 1) 101 containing the purified water _{600ml, Cr (NO 3) 3} · 9H 2 O480g pure water 1.2
0.3 l of a solution dissolved in 1 and 28% by weight of ammonia water
While stirring and, while controlling the flow rates of the two types of aqueous solutions so that the pH of the reaction solution was within the range of 7.5 to 8.5, the solution was added dropwise over about 1 hour. The obtained hydroxide slurry was filtered, washed well with pure water, and then dried at 110 ° C. When the valence of Cr contained in the dried solid was measured by a polarographic method, at least 98% or more was trivalent.

Since the weight loss rate when ignited to 600 ° C. was 26%, this chromium hydroxide is represented by the chemical formula and corresponds to Cr ₂ O ₃ .3H ₂ O. The obtained solid was ground, mixed with graphite, and pelletized by a tablet molding machine. 60 ml of these pellets were filled in a glass baking tube and heated at 400 ° C. under a H ₂ stream containing 3 vol% steam for 4 hours.
It was calcined for a period of time to obtain a catalyst precursor.

FIG. 1 shows the XRD pattern of this precursor. It can be seen that crystalline Cr ₂ O ₃ is growing. CuKα ₁ ray was used as the X-ray source. 2θ =
The peaks at 26.5 ° and 54.7 ° are derived from graphite added during molding. 40 ml of the precursor was filled in an Inconel reaction tube and diluted with N _{2 at} atmospheric pressure to 20 vol.
% HF airflow at 350 ° C., followed by no N ₂ dilution 10
The fluorination treatment was carried out at 350 ° C. in a 0% HF gas stream, and further in a 100% HF gas stream at a pressure of 3 kg / cm ² G.
The composition of the pellets after the treatment is shown below.

Cr: 60.1% O: 20.8% F:
16.5% (Catalyst Preparation Example 2) 60 ml of dried pellets prepared in the same manner as in Catalyst Preparation Example 1 were filled in a glass calcination tube, and first calcined at 350 ° C. for 2 hours under N ₂ gas flow. It was calcined at 400 ° C. for 4 hours under H ₂ stream to obtain a catalyst precursor. The growth of crystalline Cr ₂ O ₃ was confirmed from the XRD pattern of the precursor.

Further, the precursor was fluorinated as in Preparation Example 1. The composition of the pellets after the treatment is shown below. Cr: 60.0% O: 20.6% F: 16.7% (Comparative Catalyst Preparation Example 1) 60 ml of dried pellets prepared in the same manner as in Preparation Example 1 was charged into a glass calcination tube, and N was added.
_{It was} calcined at 400 ° C. for 4 hours under _two air streams to obtain a catalyst precursor.

FIG. 2 shows the XRD pattern of this precursor. It can be seen that there are no crystalline compounds. Further, the precursor was fluorinated as in Preparation Example 1. The composition of the pellets after the treatment is shown below. Cr: 57.8% O: 17.3% F: 22.2% Although the fluorination treatment was performed under the same conditions as in Preparation Example 1, it can be seen that the O content is low and the F content is high. (Catalyst Preparation Example 3) Cr (NO ₃ ) was added to a 20 l reaction vessel.
Was prepared Cr solution put ₃ · 9H ₂ O420g and pure water 5l. 625 g of 10% ammonia water was added dropwise thereto over 3 minutes while vigorously stirring. A precursor was prepared according to the method of Preparation Example 1 using the obtained hydroxide slurry. The growth of crystalline Cr ₂ O ₃ was confirmed from the XRD pattern of the precursor.

2θ = 31 to 35.5 for this precursor
The peak half width was measured in the range of ° under the following conditions. FIG.
The results are shown in. The full width at half maximum was 1.2 ° (value corrected by the spread of 0.12 ° of the line derived from the optical system of the apparatus obtained from the measurement of the silicon single crystal). The specific surface area of this precursor was 210 m ² / g.

Measuring condition of peak half width Measuring device: Physical X-ray diffractometer RAD-B X-ray output; 50kV-180mA divergence slit; 1.0 ° scattering slit; 0.5 ° lecture slit; 0.15mm scan speed 1 ° / min step; 0.002 ° measurement mode; θ-2θ precursor 40 ml was filled in an Inconel reaction tube, and diluted with N _{2 at} atmospheric pressure under a 20 vol% HF gas stream at 360 ° C.
Then, 360% under 100% HF gas flow without N ₂ dilution.
Fluorination treatment was performed at ° C. The composition of the pellets after the treatment is shown below.

Cr: 62.3% O: 24.4% F:
10.3% (Comparative Catalyst Preparation Example 2) 60 ml of dried pellets prepared by the same method as in Catalyst Preparation Example 3 was filled in a glass calcination tube, and air diluted with nitrogen under atmospheric pressure (O ₂ concentration ₂ vol%). The temperature was raised under an air stream. When the outside temperature of the firing tube suddenly increased around 370 ° C., the inside temperature of the firing tube suddenly rose to about 450 ° C., and after a few minutes, the temperature again recovered to almost the same temperature as the outside temperature of the firing tube. After reaching 400 ° C., the temperature was maintained for 4 hours.

The peak half-width of this precursor was measured in the same manner as in Preparation Example 3. FIG. 4 shows the results. The half-width is 0.
It was 7 °. The specific surface area of this precursor is 36 m ² /
g. Comparing with the results of Preparation Example 3, it can be seen that the precursor fired in H ₂ has a larger half width of diffraction line and a larger specific surface area than the precursor fired in air. (Catalyst preparation example 4) 40 ml of the precursor obtained in catalyst preparation example 1
Was charged into an Inconel reaction tube, and the fluorination catalyst was carried out at 350 ° C. in a N ₂ -diluted CFC 13 (CF ₃ Cl) stream at atmospheric pressure, and subsequently in a 100% CFC 13 stream at 350 ° C. The composition of the pellets after the treatment is shown below.

Cr: 60.4% O: 23.7% F:
8.8% Cl: 3.1% (Catalyst Preparation Example _{5) Cr (NO 3) 3} · 9H 2 O 480
Reduce from g to _{432g, Zn (NO 3) 2} · 6H 2 O
A catalyst precursor was prepared according to Preparation Example 1 except that 36 g of was added.

Further, the precursor was fluorinated in the same manner as in Preparation Example 1. (Catalyst Preparation Example _{6) Cr (NO 3) 3} · 9H 2 O 480
Reduce from g to _{432g, Cd (NO 3) 2} · 4H 2 O
A catalyst precursor was prepared according to Preparation Example 1 except that 32 g of was added.

Further, the precursor was fluorinated as in Preparation Example 1. (Catalyst Preparation Example _{7) Cr (NO 3) 3} · 9H 2 O 480
Reduce from g to _{432g, Cu (NO 3) 2} · 3H 2 O
A catalyst precursor was prepared according to Preparation Example 1 except that 6 g was added.

Further, the precursor was fluorinated as in Preparation Example 1. (Catalyst Preparation Example _{8) Cr (NO 3) 3} · 9H 2 O 480
A catalyst precursor was prepared according to Preparation Example 1 except that the amount was reduced from 4 to 432 g and 9 g of AgNO ₃ was added. Further, the precursor was fluorinated as in Preparation Example 1. (Catalyst Preparation Example _{9) Cr (NO 3) 3} · 9H 2 O 480
A catalyst precursor was prepared according to Preparation Example 1 except that the amount was reduced from 4 g to 432 g and 9 g of Pb (NO ₃ ) ₂ was added.

Further, the precursor was fluorinated as in Preparation Example 1. (Fluorination Reaction Example 1) Catalyst 30 prepared in Catalyst Preparation Example 1
ml in a reaction tube made of Inconel, and H under the following reaction conditions
The fluorination reaction of trichlorethylene with F was performed.

The outlet gas of the reaction tube was blown into a two-phase trap of alkali and toluene to remove unreacted HF and generated HCl, and the components extracted in toluene were analyzed by gas chromatography. The results are shown in Table 1. Temperature: 210 ° C., pressure: atmospheric pressure, molar ratio: 15, SV:
1000 h ^-1 (fluorination comparative reaction example 1) Trichlorethylene fluorination reaction was performed in the same manner as in fluorination reaction example 1 except that the catalyst prepared in comparative catalyst preparation example 1 was used. The results are also shown in Table 1.

Table 1 Results of Fluorination Reaction of Trichlorethylene TCE Conversion 133a Selectivity 134a Selectivity Example (%) (%) (%) Reaction Example 1 90.2 95.3 1.0 Comparative Reaction Example 1 66.3 70 .9 0.3 In the table, TCE conversion rate, 133a selectivity and 134a selectivity are respectively trichlorethylene conversion rate and HCFC-.
133a, HFC-134a selectivity is shown. (Fluorination Reaction Example 2) Catalyst 30 prepared in Catalyst Preparation Example 1
ml in a reaction tube made of Inconel, and H under the following reaction conditions
The fluorination reaction of HCFC-133a with F was performed.

The outlet gas of the reaction tube was blown into an alkali trap to remove unreacted HF and generated HCl, and the gas composition was analyzed by gas chromatography. Table 2 shows the results. Temperature: 320 ° C., pressure: 2 kg / cm ² G, molar ratio: 8, S
V: 1500h ^-1 (fluorination reaction example 3) Catalyst 30 prepared in catalyst preparation example 2
HCFC-1 in the same manner as in fluorination reaction example 2 using ml.
The fluorination reaction of 33a was performed. The results are also shown in Table 2. Fluorination Comparative Reaction Example 2 HC was prepared in the same manner as in Fluorination Reaction Example 2 except that the catalyst prepared in Comparative Catalyst Preparation Example 1 was used.
The fluorination reaction of FC-133a was performed. The results are also shown in Table 2.

Table 2 Results of fluorination reaction of HCFC-133a Reaction temperature 134a Yield 134a Selectivity Example (° C) (%) (%) Reaction Example 2 320 19.0 99.4 Reaction Example 3 320 19.1 99. 3 Comparative Reaction Example 2 320 16.9 99.2 In the table, 134a yield and 134a selectivity are respectively HC.
The yield and selectivity of FC-134a are shown. (Fluorination Reaction Example 4) Catalyst 30 prepared in Catalyst Preparation Example 3
The fluorination reaction of HCFC-133a was performed in the same manner as in the fluorination reaction example 2 except that the reaction temperature was changed to 325 ° C. using ml. The results are shown in Table 3. (Fluorination Reaction Example 5) Catalyst 30 prepared in Catalyst Preparation Example 4
The fluorination reaction of HCFC-133a was performed in the same manner as in the fluorination reaction example 2 except that the reaction temperature was changed to 325 ° C. using ml. The results are also shown in Table 3.

Table 3 Results of fluorination reaction of HCFC-133a Reaction temperature 134a Yield 134a Selectivity Example (° C) (%) (%) Reaction Example 2 320 19.0 99.4 Reaction Example 3 320 19.1 99. 3 Comparative reaction example 2 320 16.9 99.2 Reaction example 4 325 19.8 99.3 Reaction example 5 325 17.0 99.0 In the table, 134a yield and 134a selectivity are respectively HC.
The yield and selectivity of FC-134a are shown. (Fluorination Reaction Example 6) 30 ml of the catalyst precursor prepared in Catalyst Preparation Example 1 was filled in an Inconel reaction tube and HF was fluorinated by HF under the following reaction conditions without fluorination by HF.
The fluorination reaction of C-133a was started, and the gas composition was analyzed according to fluorination reaction example 2.

Temperature: 320 ° C., pressure: atmospheric pressure, molar ratio:
8, SV: 1500h ^-1 cause ΔT of about 50 ° C. to the catalyst layer immediately after the start of the reaction, then heating was gradually reduced. HFC-134a was scarcely produced at 10 minutes after the start of the reaction, but 3
After a lapse of time, HFC-134a came to be obtained with a yield of 5%. (Fluorination Reaction Examples 7 to 11) The fluorination reaction of HCFC-133a is carried out in the same manner as in Fluorination Reaction Example 2 except that the reaction temperature is set to 315 ° C. using 30 ml of the catalyst prepared in Catalyst Preparation Examples 5 to 9. It was The results are shown in Table 4.

[0060] Table 4 HCFC-133a fluorination reaction results of Example Catalyst 134a yield (%) 134a selectivity (%) Reaction Example 7 Preparation Example 5 17.8 99.4 Reaction Example 8 Preparation Example 6 16.9 99. 4 Reaction example 9 Preparation example 7 14.5 99.2 Reaction example 10 Preparation example 8 16.5 99.2 Reaction example 11 Preparation example 9 15.8 99.2 In the table, 134a yield and 134a selectivity are respectively HF
The yield and selectivity of C-134a are shown. (Fluorination Reaction Example 12) Catalyst 3 prepared in Catalyst Preparation Example 1
0 ml was filled in a reaction tube made of Inconel, and the fluorination reaction of dichloromethane with HF was performed under the following reaction conditions. The outlet gas of the reaction tube was blown into a heated alkali trap to remove unreacted HF and generated HCl, and the gas composition was analyzed by gas chromatography.

Temperature: 200 ° C., pressure: atmospheric pressure, molar ratio:
6, SV: 2000h ^-1 Unreacted dichloromethane was 41%, and the yields of main products were as follows. HFC-32 50%, HCFC-318 8% (fluorination reaction example 13) Catalyst 3 prepared in catalyst preparation example 1
0 ml was filled in an Inconel reaction tube, and fluorination reaction of perchlorethylene with HF was performed under the following reaction conditions. The outlet gas of the reaction tube was blown into a trap composed of two phases of alkali and toluene to remove unreacted HF and generated HCl, and the components extracted in toluene were analyzed by gas chromatography.

Temperature: 340 ° C., pressure: atmospheric pressure, molar ratio:
5, SV: 1000 h ^-1 unreacted perchlorethylene was 30%, and the yield of main products was as follows. HFC-125 5.6%, HCFC-124
15.5%, HCFC-123 38.2%

[0063]

EFFECTS OF THE INVENTION The fluorination catalyst produced by the method for producing a catalyst of the present invention has high activity, and the target compound can be obtained in high yield in the fluorination reaction of halogenated hydrocarbons with HF. Also,
The reaction can be carried out at a low temperature, resulting in a long catalyst life.

[Brief description of drawings]

FIG. 1 is an XRD pattern of a catalyst precursor of Catalyst Preparation Example 1.

FIG. 2 is an XRD pattern of a catalyst precursor of Comparative Catalyst Preparation Example 1.

FIG. 3 is an XRD pattern of a catalyst precursor of Catalyst Preparation Example 3.

FIG. 4 is an XRD pattern of a catalyst precursor of Comparative Catalyst Preparation Example 2.

Claims (9)

[Claims] 1. A method for producing a chromium-based fluorination catalyst, which comprises firing a raw material containing trivalent chromium hydroxide as a main component at a temperature of 350 ° C. or higher and 500 ° C. or lower in the presence of hydrogen. 2. A raw material containing trivalent chromium hydroxide as a main component is first heat-treated in an inert gas stream at a temperature of 100 ° C. or higher and 600 ° C. or lower, and then in the presence of hydrogen, 350 ° C. or higher and 500 ° C. or lower. A method for producing a chromium-based fluorination catalyst, which comprises firing at a temperature of. 3. The method for producing a chromium-based fluorination catalyst according to claim 1, wherein the fluorination catalyst is partially fluorinated after firing in the presence of hydrogen. 4. The chromium-based fluorine according to claim 3, which is partially fluorinated at a temperature of 300 ° C. or more and 500 ° C. or less in an air flow containing hydrogen fluoride after firing in the presence of hydrogen. Method for producing chemical catalyst. 5. A raw material containing trivalent chromium hydroxide as a main component is at least one element selected from the group consisting of cobalt, nickel, copper, silver, zinc, cadmium, mercury, aluminum, gallium, tin and lead. The method for producing a chromium-based fluorination catalyst according to any one of claims 1 to 4, further comprising: 6. A fluorination catalyst or a precursor produced by the method according to claim 1, wherein the half width of the diffraction peak of an X-ray diffraction pattern is 1% by volume or more at atmospheric pressure for the same raw material as described above. A fluorination catalyst or a precursor, which has a half value width of 1.2 times or more of a corresponding diffraction peak of a material obtained by firing at 400 ° C. for 2 hours or more in an atmosphere containing oxygen. 7. An X-ray diffraction diagram having a diffraction peak of crystalline Cr ₂ O ₃ and a lattice spacing d of 2.65 to 2.69.
The fluorination catalyst is characterized in that the half width of the peak located in the range is 0.8 ° or more. 8. A halogenated carbonization characterized by catalyzing a halogenated hydrocarbon having 1 to 4 carbon atoms and hydrogen fluoride in a gas phase in the presence of the fluorination catalyst according to any one of claims 1 to 7. Method for fluorinating hydrogen. 9. The fluorination method according to claim 8, wherein the halogenated hydrocarbon is a hydrogen-containing halogenated hydrocarbon.