WO1997010053A1

WO1997010053A1 - Catalyst for fluorinating halohydrocarbon

Info

Publication number: WO1997010053A1
Application number: PCT/CN1996/000061
Authority: WO
Inventors: Jian Lu; Hengdao Quan; Huifang Li; Hui'e Yang; Zhenyu Wang; Zhong Li; Lei Shi; Hongxiang Qu; Zhixia Zhao; Jie Li; Zhongzhang Hao; Huili Li
Original assignee: Xi'an Institute Of Modern Chemistry
Priority date: 1995-09-13
Filing date: 1996-08-09
Publication date: 1997-03-20
Also published as: CN1145275A; CN1041804C

Abstract

This invention provides a catalyst for fluorinating halohydrocarbon, which consists of a support and active components deposited thereon. Said support is active AlF3 prepared by fluorinating silica (SiO2) containing gamma-alumina at 150-300 °C with a mixture of anhydrous hydrogen fluoride and nitrogen. Said active components contain chromium, cobalt and magnesium in a proportion of Cr:Co:Mg=1-10:1:0.1 (weight ratio). The catalyst is obtained by impregnating said active A1F3 with a solution of chlorides of Cr, Co and Mg. The catalyst which is useful in the fluorinating of trichlorethylene in the vapor phase to form R-134a has high activity, selectivity and a long life of use.

Description

TECHNICAL FIELD

The invention relates to a fluorination catalyst, which is mainly used for the gas-phase fluorination reaction of halogenated hydrocarbons and hydrogen fluoride. Background technique

It is known that three gas ethylene (TCE) and hydrogen fluoride are reacted in the gas phase to synthesize 1, 1, 1, 2-tetrafluoroethane (referred to as R-134a). The fluorination catalyst used is Cr ₂ 0 ₃ / Al ₂ 0 ₃ . Experiments have shown that catalysts such as chromium, fluorine, and oxides are used in the gas phase. Direct trifluoride ethylene is fluorinated. Only 3% of 134a can be obtained. In addition, the catalyst's activity rapidly decays, and the catalyst needs to be frequently regenerated. Replacement. Obviously not conducive to industrial production. ·

EP29 $, 885A1 reports a method for preparing R-134a. The catalyst is a commercial r-Al ₂ 0 ₃ carrier (specific surface area> 100m2 g-1), which is impregnated with an active metal compound and then dried in a reaction tube. Fluorinated. All r -Al ₂ 0 ₃ fluorinated with HF in the reaction tube is converted into A1F ₃ .

US4.861, 744 reports a method for preparing 1, 1, 1-triazine-2-gas ethane (referred to as R-133a) from trichloroethylene and hydrogen fluoride through gas-phase catalytic fluorination. The catalyst is also activated alumina ( E.g. Al undna

A-201 has a bulk density of 0.53gml_l and a specific surface area of 325m2 g "l. After being impregnated with the active ingredient, it is dried and fluorinated.

US4, 922, 037 has also been reported to r -Al ₂ 0 ₃ or activated carbon as the carrier was prepared in a similar manner the gasification catalyst *

In summary, most of the catalysts reported so far for preparing R-133a and R-134a are based on activated alumina. The active components are impregnated, dried, and fluorinated. There are obvious shortcomings in this process: (1) the reaction of A1 ₂ 0 ₃ to A1F ₃ produces a large amount of water 'to cause the soluble active components to be lost; (2) the importance of temperature control during the fluorination process is not emphasized . Excessive fluorination temperature can easily cause 5 1F ₃ crystal phase transformation and grain growth, reducing the activity of the catalyst.

EP0408005A1 reports a catalyst preparation method using A1F ₃ as a support. The specific surface area of A1F _{3 used} is only 26tn2 g-1, and the exact crystal phase and composition of its support are not disclosed. It supports a single trivalent chromium compound (CrCl ₃ · 6Η ₂ 0), and no other co-catalyst is added, so it is difficult to ensure Optimum catalyst selectivity and stable catalytic activity

It has been proved that the crystal phase composition and specific surface area of A1F3 as a gasification catalyst support are closely related to the activity of the catalyst. In general, the supported catalyst has a higher τ content when the content of τ is larger and the specific surface area is larger.

-1- correction page ISA / CM The catalytic activity of A1F ₃ is very low. When A1F ₃ is prepared from Al ₂ 0 ₃ by conventional gas phase fluorination, the specific surface area of A1F ₃ is greatly reduced due to the strong exothermic reaction. The content of r-crystalline phase and amorphous phase is also greatly reduced.

The purpose of the present invention is to overcome the shortcomings of the background technology. Design a fluorination catalyst with a high A1 F ₃ content, a large specific surface area, and a large pore volume. The active ingredient is evenly distributed on the support.

The concept of the present invention: To achieve the above-mentioned objective, the catalyst prepared by the traditional method cannot be achieved. The existing method for expanding the specific surface area and pore volume of the carrier is to add carbon black, paraffin, and polyvinyl alcohol as pore-forming agents. When burned, the generated gas can be removed to produce pores. However, these pore formers must react at a temperature higher than 50 TC. For the r-A1F ₃ crystal form. Under such high temperature conditions, grain growth will occur, and r-AlF _{3 will} change to "-A1F ₃ " with a significant decrease in specific surface area.

Another method for preparing a pseudo specific surface catalyst is to uniformly precipitate the components required for the catalyst from an aqueous solution. However, the A1F ₃ prepared by this method is powdery, and the mechanical strength after molding is very low, so it has no application value.

In order to obtain Γ-A1F ₃ with a high specific surface area and a large pore volume, the first used at 150-

At a temperature of 300 ° C, the pore-forming agent was also removed by fluorination at the same time as the gasification of Al ₂ 0 ₃ , which broke the traditional method of high-temperature burning and displacing the pore-forming agent. The use of Si0 ₂ as a pore-forming agent is based on the characteristics of the chain structure of Si0 ₂ and the easy reaction with HF to form volatile fluorinated silicon compounds. Once removed by fluorination, it will leave a continuous pore structure, thereby increasing the specific surface area and The pore volume is superior to the existing pore structure of A1F ₃ , has a specific surface area of rhenium, a large pore volume, and relatively low mechanical strength.

The fluorination catalyst for fluorinated halohydrocarbons according to the present invention is characterized in that r-A1 ₂ 0 ₃ containing Si0 ₂ is 3-20%, mixed gas with anhydrous hydrogen fluoride and nitrogen, and pure anhydrous HF, at 150 -Gas-phase fluorination at 300 ° C to drive off A1F ₃ carrier as a pore-forming agent with specific surface area

> 40m ² g " ¹ , pore volume> 0. 18ralg— ¹ , average pore diameter <9θΑ, r-AIF3 content>

50%, A1F ₃ content> 90¾. The average grain size is <15θΑ. Dipping method using supported chromium chloride, cobalt and magnesium, which mass ratio of metal ion: 1 to 10: 1: 0.1 cured at 120- 3 ⁵ 0 ° C with nitrogen or air and then at 180 350 ^e C was activated with a mixture of silver hydrogen and nitrogen.

Compared with the prior art, the present invention has the following advantages:

-2- Correction page ISA / CN (1) The carrier A1F ₃ has a large specific surface area and pore volume. Suitable pore size distribution.

(2) The support is r—AlF _3. Crystal phase transformation and grain growth do not occur during the reaction.

(3) r-A1F ₃ supports active components Cr ³⁺ , Co ²⁺ , Mg ²⁺ , and the prepared catalyst enables the fluorination reaction to proceed at a lower temperature. And has the best selectivity. And lasting Catalytic activity.

(4) This fluoride catalyst can be used in the fluorine-chlorine exchange reaction of various halogenated hydrocarbons. Best way to achieve invention

Examples

1. 145.4 g of A1 (0Η) _{3 is} reacted with excess NaOH to prepare a sodium metaaluminate solution. Water sodium glass containing Na ₂ Si0 ₃ is added to 10.2 g, and the precipitant C0 _{2 is} passed through the filter. After drying and firing, -Al ₂ 0 ₃ containing SiO ₂ 5% was obtained. The product was fluorinated at 150 ° C for 4h with a mixture of HF: N ₂ = 1: 4, then gradually increased the HF concentration to pure HF for 8h, and then heated to 200 ° C for 3h. The resulting A1F ₃ carrier was used dipping method supported chromium, cobalt, magnesium metal ions in a weight ratio of 5: 1: 0.1, i.e., 5% Cr3 ten, 1¾ (:. ₀ 2 + and 0.1¾Mg ²⁺ nickel reactor, 120 ° C, N ₂ Airflow (50ml mm "¹;) After 12 hours of treatment, the temperature was raised to 350 ° C at a temperature rise rate of rCmin" ¹ and the solidified catalyst was cured for 6 hours. The cured catalyst was passed HF at 180 ° C: N ₂

After the 1: 1 mixture was activated for 4h, it was changed to pure HF, and then heated to 35Q ° C at a rate of rCrwrT ^{1 for} 10h to prepare a fluorination catalyst.

Characterized carrier A1F _3; vector measured by the BET low temperature nitrogen adsorption specific surface area A1F ₃ to 57 _m 2 g "l, a pore volume of 0.25mlg ^_1, average pore diameter 4θΑ.

X-ray powder diffraction was used to determine 70% r-A1F _{3 in the} crystal phase of the carrier. The content of A1F ₃ was

90%. Average grain size is 9 8 A.

The reaction of the above-obtained fluoride catalyst for the synthesis of R-134a is as follows:

CC1 ₂ = CHC1 + 3HF CF ₃ CH ₂ C1 + 2HC1 (1)

TCE R-133a

CF ₃ C¾C1 + HF-CF ₃ CH ₂ F Ten HC1 (2)

R-134a

Reaction (1) using 30ml catalyst, at 260 ° C, TCE: HF = 1: 6, contact time is ^3.4 s, TCE conversion rate is 98¾, the selectivity to R-133a is 99¾ 'at 280 ° C reaction TCE conversion rate under the same conditions

-3- Correction page ISA / CN 100% and selectivity 99%. The above fluorination catalyst is used in reaction (2), that is, the same kind of rebel catalyst is used in the two-step reaction. When R-133a: HF = 1: 10 and contact time is 16.4s, the conversion rate of R-133a 32%, the selectivity to 134a is 99%; when the contact time is 8.2s, the conversion is 25¾. The selectivity is 99¾; when the contact time is 5.3s, the conversion is 23% and the selectivity is 99%, After the reaction for 1000 h, the crystal phase of the support was still r-AlF ₃ and the average grain size was 10 lA.

2, with reference to embodiments Example 1, except that the Si0 ₂ 10¾ prepared containing the resulting r -Al ₂ 0 ₃ carrier fluorinated A1F _3, a specific surface area of 50m ² g- ^1, pore volume 0.23mlg- ¹ , having an average pore diameter - A1F ₃ is 87¾, A1F ₃ content of 95% and an average grain size of 105A. The loaded active components still contain: Cr ³ 105%> Co ² 10 1¾, Mg ²⁺ 0.1% »

In reaction (1), using 30ml of fluorinated catalyst at 260 ° C, TCE: HF = 1: 6, contact time is 3.4s, the conversion rate of TCE is 96¾, and the selectivity to R-133a is 99¾. Under the same conditions of 280 ° C, the conversion of the reaction was 100%, and the selectivity was 99%. The above catalyst is used in reaction (2). When R-133a: HF = 1: 10 and contact time is 16.4s, the conversion of R-133a is 30 and selectivity is 99¾; when contact time is 8.2s, conversion The rate is 23¾ and the selectivity is 99¾. When the contact time is 5.35, the conversion is 21¾ and the selectivity is 99¾. After 1000 hours of reaction, the carrier A1F _{3 is} still dominated by crystalline phase, and the average grain size is still 105A.

3, with reference to Example 1, except that the eight ^ prepared containing the resulting Si0 ₂ 15¾ fluorinated carrier _3, a specific surface area 42ra ² g- ^1, pore volume 0.20ralg- ^1, the average pore size 73A, containing r-A1F ₃

100%. The content of A1F ₃ is ιοο¾. The average grain size is 110A.

In reaction (1), a 30ml fluorinated catalyst was used at 260 ° C, TCE: HF = 1: 6, and the contact time was 3.4s. The conversion rate of TCE was 94%, and the selectivity to R_133a was 99¾. Under the same conditions at 280 ° C, the conversion of TCE was 98%, and the selectivity to R-133a was 99¾. The above catalyst was used in reaction (2). When R-133a: HF = 1: 10 and contact time was 16.4s, the conversion of R-133a was 27%, and the selectivity to R-134a was 99¾. When the contact time is 8.2s, the conversion is 22% and the selectivity is 99¾; when the contact time is 5.3s, the conversion is 19¾ and the selectivity is 99¾.

4. Implementation with reference to Example 1, the difference is that the ratio of loading chromium, cobalt, and magnesium is 2: 1: 0.1, that is,

2¾Cr ³十, l¾Co ²十, 0.1% Mg ²⁺ .

The reaction (1) uses a 30ral fluorination catalyst at 260 ° C, TCE: HF = 1: 6, and the contact time is 3.4s, the TCE conversion rate is 90%, and the selectivity to R-133a is 99¾, Under the same conditions at 280 ° 0, the conversion was 95¾ and the selectivity was 99%. The above catalyst is used in reaction (2). When Rl ³ 3a _: HF = 1:10, contact time is 16.4s, R- 133a conversion rate is 25%, selectivity is 99¾; when contact time is 8.2s, conversion Rate

-4—

Correction page 17¾, the selectivity is 99¾; when the contact time is 5.3s, the conversion rate is 13%, and the selectivity is 99¾.

5. Implementation with reference to Example 1. The difference is that the proportion of chromium, cobalt, and magnesium ions supported is

10: 1: 0.1, that is, 10¾Cr ³⁺ , l¾Co ² ten, 0.1% g ²⁺ .

Reaction (1) Using a catalyst of 30 ₁₁₁ 1 at 260 ° 0 ::: 1 ^ _: 1 ^ = 1 _: 6, with a contact time of 3.4 ₅ and a TCE conversion rate of 98%, the choice of generating R-133a The property is 99%, and the reaction is performed under the same conditions at 280 ° C. The conversion rate is 100% and the selectivity is 99%. The above fluorination catalyst is used in the reaction (2), when R-133a: HF = 1: 10. the contact time of the conversion 16.4s, 133 rate 32¾, selectivity 99¾; ₅ when the contact time was 8.2 inches, the conversion rate of 26¾, a selectivity of 99%, the contact time is 5.3s, the conversion was 24%, Selectivity is 99%.

-5-Correction page ISA / CN

Claims

Rights request

1. A fluorination catalyst for nitrided halogenated hydrocarbons, characterized by using a mixture of r-Al ₂ 0 ₃ containing Si0 ₂ 3- 20¾ with anhydrous hydrogen fluoride and nitrogen, and pure anhydrous hydrogen fluoride at 150 "300 ° C for fluorination 'to drive out Si0 ₂ as a pore former. An activated aluminum fluoride support was prepared with a specific surface area

> 40m ² g ^_1 , pore volume X lSmlg — ¹ , average pore size <9θΑ, r— A1F ₃ content> 50¾, A1F ₃ content> 90%. Average grain size <150A. The impregnation method is used to load chromium, cobalt, and magnesium in a ratio of 1-10: 1: 0.1. Curing is performed at 12 (H350 ° C nitrogen flow. At 180 ~ 350 ° C, a mixture of hydrogen fluoride and nitrogen and pure fluorine Sulfurization was carried out. A fluorination catalyst was obtained.

2. The fluorination catalyst according to claim 1, characterized by using τ-containing 0 ₂ 5¾

A1F ₃ and anhydrous fluorination § [A mixture of nitrogen and pure anhydrous hydrogen fluoride is fluorinated at 150 ~ 200 ° C to produce an activated alumina carrier with a specific surface area of 57m2 g-1, a pore volume of 0.25mlg_l, The average pore size 4θΑ, the content of r-AlF ₃ is 70¾, the content of A1F ₃ is 90¾, and the average grain size is 98A. The ratio of chromium, cobalt and magnesium supported on the carrier is 5: 1: 0.1.

3 The fluorination catalyst according to claim 1, characterized by containing a r Si0 ₂ 10¾

A1 ₂ 0, gas phase fluorination with anhydrous hydrogen fluoride and nitrogen sticks and pure anhydrous hydrogen fluoride at 15 ° (200 ° C) to obtain an activated aluminum fluoride support with a specific surface area of 50m2 g-1 and a pore volume of 0.23 ml ₉ _1, average pore size is 52A. r—AlF ₃ content is 87¾, A1F ₃ content is 95¾. The average grain size is 105A. The carrier A1F _{3 is} loaded with the ratio of cobalt, magnesium and magnesium is 5: 1: 0.1.

4. The fluorination catalyst according to claim 1. Wherein r Si0 ₂ 15¾ containing a

Α1 ₂ 0, fluorinated with anhydrous nitriding S and nitrogen mixture and pure anhydrous hydrogen fluoride at 200 "300 ° C to obtain activated aluminum fluoride with a specific surface area of 42m2 g-1 and a pore volume of 0.20 mlg-1, average pore size is 73A, r-AlF ₃ content is 100¾, A1F ₃ content is 100¾, average grain size is 110 &.

5. Application claim 1. The fluorination catalyst is used to synthesize 1,1,1-trifluoro-2-chloroethane and 1,1,1,2,4-tetrafluoroethane in a two-step reaction using the same fluorination catalyst.

-6- Replacement page (Article 26)