CN1415414A - Catalyzer utilized to synthesize oxalate and its preparation method - Google Patents

Abstract

The invention relates to the synthesis of oxalate, in particular to a catalyst for synthesizing oxalate and a preparation method thereof. The present invention uses δ- _Al2O3 as a carrier to support Pd, Fe and La active components, and the atomic ratios of the active components Pd, Fe and La are respectively 3-0.5 _: 2-0.5:2-0.5. The crystal form is δ-Al ₂ O ₃ carrier prepared from pseudo-boehmite or aluminum salt, and the active components of two or more metals are loaded, and the mutual cooperation can effectively improve the activity and life of the catalyst. The invention is used as a catalyst for catalyzing oxalate esters. The oxalate esters can be used to manufacture oxalic acid, oxamide, ethylene glycol, and intermediates of certain medicines and dyes, and are important basic chemical raw materials. my country's coal resources are extremely rich, which is of strategic significance to the development of carbon-chemistry.

Description

Catalyst for synthesizing oxalate and preparation method thereof

Technical field

The invention relates to the synthesis of oxalate, in particular to a catalyst for synthesizing oxalate and a preparation method thereof. The present invention uses carbon monoxide and nitrite to catalyze the catalyst and preparation method of oxalate, and provides a δ-Al ₂ O ₃ crystal form suitable for the reaction prepared by different methods as a carrier, and then loaded with two The active components of one or more than two kinds of metals can effectively improve the activity and life of the catalyst by cooperating with each other.

Background technique

Oxalate can be used to manufacture oxalic acid, oxamide, ethylene glycol, and intermediates of certain drugs and dyes. It is an important basic chemical raw material and plays an important role in carbon-one chemistry. In 1965, DMFenton and others in the United States discovered that oxalic acid diester, oxalic acid diester, can be synthesized by coupling reaction of carbon monoxide in alcohol medium, using α-Al ₂ O ₃ as a carrier and metal palladium as a catalyst. After that, the United States and Japan invested a lot of funds to carry out research and development along this line of thought.

my country is extremely rich in coal resources, and CO has sufficient sources. Since the 1980s, research in this area has also been vigorously carried out in China: the preparation process of catalysts, the use of different types of active metal components, and different proportions; the composition of reaction materials, reaction temperature, and flow rate of carrier gas; improvement etc. The carriers used are all α-Al ₂ O ₃ or γ-Al ₂ O ₃ crystal forms as carriers ((1) Chen Gengshen, Yan Huimin, Xue Biao Tianqi Chemical Industry 1995, Volume 20(2) 5-9, He Fei, Gao Zhenghong, Song Ying Xu Genhui, Journal of Catalysis, 2002, May 23, (3) 223-226). Chinese patent CN1066070 C introduces the use of activated alumina, but given the surface area of Al ₂ O ₃ of 6-7M ² /g, it should be α-Al ₂ O ₃ . EP 0 108 359 A1 also uses α-Al ₂ O ₃ as a carrier.

In our experiments, we found that the catalyst made of α-Al ₂ O ₃ or γ-Al ₂ O ₃ crystal form as the support has low yield or poor life due to the pore structure and strength of the support. As shown in Table 1 and Table 2: Table 1: Catalysts made of carriers with different crystal forms, comparison of productivity and lifespan Carrier crystal form Yield life γ-Al ₂ O ₃ 1.22g/lg. ^※ 1h Difference δ-Al ₂ O ₃ 3.29g/1g1h good δ-Al ₂ O ₃ +α-Al ₂ O ₃ 2.33g/1g1h better 1g. ^※ : Refers to 1 gram of catalyst, the same below. Table 2: Structural indicators of different crystal carriers (Figure 2: Mercury Intrusion Diagram) structural items γ-Al ₂ O ₃ δ-Al ₂ O ₃ δ-Al ₂ O ₃ +α-Al ₂ O ₃ Cumulative pore volume (ml/g) 0.3931 0.5578 0.5110 Total pore specific surface area (sq-m/g) 166.530 68.876 62.117 Middle hole diameter (um) 0.0089 0.0376 0.0439 Apparent density (g/ml) 1.3918 1,1515 1.2483 Skeleton density (g/ml) 3.0736 3.2196 3.4480

Contents of the invention

The purpose of the present invention is to provide a kind of catalyst and preparation method thereof for the synthesis of oxalate, can overcome _the shortcoming of prior art, the present invention uses δ- _Al2O3 crystal form as carrier, has the most suitable pore structure and Strength, the catalyst obtained under the same conditions has better activity and life

The invention uses the δ-Al ₂ O ₃ crystal form as a carrier and supports the catalyst composed of Pd, Fe and La active components. The atomic ratios of the active ingredients are respectively 3-0.5:2-0.5:2-0.5. The pore structure of the δ-Al ₂ O ₃ carrier is: total pore volume (ml/g) 0.4-0.9; total pore surface area (m ² /g) 60-100; average pore diameter (μm) 0.03-0.05; Table The apparent density (g/ml) is 0.77-1.2; the skeleton density (g/ml) is 2.5-3.5.

The preparation method of δ- _Al2O3 carrier of _the present invention comprises:

1) Preparation of δ-Al ₂ O ₃ support from pseudoboehmite

Pulverize pseudo-boehmite and pass through a 200-400 ^# mesh sieve, add 1-3% of the powder amount to the graphite powder of the same mesh number in the obtained powder, add 1-3% CaCO as the powder amount _3. Add 45% of the powder amount of dilute HNO ₃ (concentration: 1-3%), stir evenly, and roll. Extrude strips with a diameter of 2.5mm with an extruder, dry naturally for 4 hours, dry at 120°C, and then roast according to a certain heating program.

(2) Preparation of δ-Al ₂ O ₃ support from AlCl ₃ ·6H ₂ O.

Add 5 parts of 8.6% (weight percent) AlCl ₃ ·6H ₂ O solution and 1 part of 1% NH ₄ OH solution into the reactor under stirring, react at 70°C, and the pH value is at 7 -8. Stand for 30 minutes, filter with suction, and wash with water until no ^Cl- can be detected. Dry at 120°C, then add graphite, CaCO ₃ , and dilute HNO ₃ according to the ratio of (1), roll, extrude into thin columnar strips with a diameter of 2.5mm, dry naturally for 5 hours, dry at 120°C, press a certain amount Program roasting.

Al ₂ (SO ₄ ) ₃ ·6H ₂ O and Al(NO ₃ ) ₃ ·6H ₂ O can be used instead of AlCl ₃ ·6H ₂ O to prepare the carrier of δ-Al ₂ O ₃ crystal form.

Described roasting heating-up program is as follows:

Keep warm at 200°C for 20-40 minutes Keep warm at 250°C for 20-35 minutes Keep warm at 300°C for 2-4 hours

Keep warm at 500°C for 20-40 minutes Keep warm at 600°C for 20-30 minutes Keep warm at 900°C for 4-9 hours

Cool naturally to room temperature. As shown in X-Diffraction Figure 1, 45.4° is the secondary main peak of δ-Al ₂ O ₃ .

The present invention uses δ-Al ₂ O ₃ as the catalyst preparation method of carrier, comprises the following steps:

1) Use the halides, nitrates, and sulfates of Pd, Fe, and La to prepare the impregnation solution according to the metering, and add acid to control the pH between 1-4.5, so as to prevent the hydrolysis of metal ions to form hydroxide precipitation and affect the impregnation of the carrier .

2) Add the δ-Al ₂ O ₃ carrier with proper pore structure and strength into the immersion solution and soak for 2-8 hours.

3) Separate and dry, soak in mixed alkali solution for 4-6 hours at 70°C, and wash to remove negative ions.

4) Drying and reducing with H ₂ for 3-5 hours at 220-550°C can make different types of catalysts.

The present invention uses δ-Al ₂ O ₃ as the catalyst of the carrier and is applied to the reaction of carbon monoxide and nitrite gas-phase catalytic synthesis of oxalate ester as follows:

coupling reaction: Among them: R alkane (CH ₃ -, C ₂ H ₅ -, C ₄ H ₉ -)

Regeneration reaction:

The synthesis of oxalate uses a fixed bed device, and the reaction tube is a jacket structure. The innermost layer has a hard glass tube with an inner diameter of 10-20mm and a length of 300-350mm. It can hold 1-80ml of catalyst, and the top of the catalyst layer is installed separately. 100mm thick glass fiber for preheating the reaction feed gas. The middle layer is filled with heating white oil and mercury conductive meter (to control temperature), the outer wall is wrapped with a layer of asbestos paper, wrapped with resistance wire, the outermost layer is protected with asbestos cloth, and the temperature of the catalyst bed is controlled by a relay. There are three outlets on the reaction tube. The middle port on the top is inserted into the ground thermometer to measure the temperature of the reaction zone. The side port is connected to the gasification tube, and the reaction raw material gas is mixed into the reactor. The bottom port is the outflow product and tail gas port. The 102G gas chromatograph produced by Shanghai Analytical Instrument Factory was used for detection, and 5A molecular sieve was used as chromatographic column filler, and the column length was 4 meters.

The ratio of CO to RONO is generally controlled at 15-30 to 10-15 (volume ratio), the contact time is 0.5-3 seconds, the activation temperature of the catalyst is 120-140°C, and the reaction temperature is 100-130°C.

The catalyst with α-Al ₂ O ₃ or γ-Al ₂ O ₃ crystal form as carrier is not the best choice, but the carrier of δ-Al ₂ O ₃ crystal form in the present invention has the best performance without special treatment. Excellent pore structure and strength, simple process. The catalyst obtained under the same conditions has better activity and lifetime. The appropriate pore structure of the catalyst is conducive to the diffusion of reactants and products. The γ-Al ₂ O ₃ crystal form has a large specific surface due to the small pores, but this pore structure is not conducive to the diffusion of reactants and products, resulting in low activity. Due to its low skeleton density and poor carrier strength, it is easy to cause pulverization and inactivation. Judging from the δ-Al ₂ O ₃ +α-Al ₂ O ₃ mixed crystal form, as the calcination temperature rises and the time prolongs, the α-Al ₂ O ₃ crystal form will be formed, and the cumulative pore volume and specific surface area will be different. The reduction is also unfavorable to the improvement of catalyst activity, but its skeleton density is high, and the strength of the catalyst can be appropriately increased. Combining the two aspects, the δ-Al ₂ O ₃ crystal support has a suitable pore structure and strength, and the prepared catalyst has high activity and life.

Description of drawings

Fig. 1 X-diffraction pattern of δ-Al ₂ O ₃ .

Figure 2 Mercury injection curve (a) Differential curve (b) Integral curve.

Detailed ways

Example 1: Preparation of δ-Al ₂ O ₃ carrier with pseudo-boehmite.

With one part of pseudo-boehmite provided by Fushun Petroleum No. 3 Factory, pulverize through a 320 ^# mesh sieve to obtain powder, add 2% graphite powder of the same mesh number of powder weight, and then add 2% _CaCO3 of powder weight, Mix evenly, then add dilute nitric acid (concentration: 2%) with 45% of powder weight, stir evenly and roll for several times, extrude strips with a diameter of 2.5mm with an extruder, and dry naturally for 4 hours at 120°C Under drying, according to the following heating program roasting. 20 minutes at 200°C, 20 minutes at 250°C, 2 hours at 300°C, 30 minutes at 500°C, 50 minutes at 600°C, and 8 hours at 900°C. Cool naturally from 900°C to room temperature.

Example 2: Preparation of δ-Al ₂ O ₃ support with AlCl ₃ 6H ₂ O

Take 5 parts of AlCl ₃ ·6H ₂ O solution with a concentration of 8.5% (weight ratio), and 1 part of a 1% NH ₄ OH solution, stir and add to the reactor at 70°C, and use 1% Adjust the pH value between 7-8 with HCl, age for 30 minutes, filter with suction, and wash with distilled water until no ^Cl- ions can be detected. Dry at 120 DEG C, pulverize and cross 320 ^# mesh sieves, with embodiment 1, add 1% graphite, 1% CaCO ₃ mix homogeneously, then add 45% dilute nitric acid (concentration is 1%), stir evenly, repeatedly grind Press, extrude into strips with a diameter of 2.5 mm, dry naturally for 6 hours, dry at 120 ° C, and roast according to the following temperature rise program. 20 minutes at 200°C, 20 minutes at 250°C, 2 hours at 300°C, 30 minutes at 500°C, 50 minutes at 600°C, and 8 hours at 900°C. Cool naturally from 900°C to room temperature.

Example 3:

Prepare a 0.1M _FeCl3 solution.

Use 1.6657g of PdCl ₂ and 1g of NaCl to make a 100ml solution.

Use 1gNaOH and 1.5gNaHCO ₃ to make 100ml of mixed lye.

Take 5ml of PdCl ₂ solution, 4.7ml of FeCl ₃ solution, add 5ml of distilled water, stir and mix, impregnate 5g of γ-Al ₂ O ₃ crystal carrier for 5 hours, separate and dry. Immerse with 5ml of mixed lye for 6 hours, filter, wash until free of Cl- ^, and then dry. Replace with _H2 at 540 °C for 4 h. The atomic ratio of Fe and Pd is about 1:1. A Pd-Fe/γ-Al ₂ O ₃ type catalyst was obtained.

Take 2g of the newly prepared Pd-Fe/γ-Al ₂ O ₃ catalyst of Example 3, N ₂ flow rate 300ml/min, activation at 140°C for 3 hours, reaction temperature 110-120°C. The flow rates of N ₂ and CO were 220 ml/min and 130 ml/min, respectively. The ratio of CO and RONO is controlled at 15-30 to 10-15 (volume ratio). The average yield was 1.22g/1g-1h, after two cycles, the activity decreased by nearly half in the second cycle.

Example 4

Take 5 parts of δ-Al ₂ O ₃ carrier, add 5ml of PdCl ₂ solution prepared in Example 3, soak for 4 hours, add 10ml of mixed lye, soak for 5 hours at 70°C, filter, and dry. _H2 reduction at 300 °C for 3 h. Take 4.7ml of FeCl ₃ solution, soak for 4 hours, then soak with 5ml of mixed lye for 5 hours, filter and wash until no ^Cl- ions can be detected. After drying, reduce with H ₂ at 500°C for 4 hours to prepare a Pd-Fe/δ-Al ₂ O ₃ two-component catalyst. The atomic ratio of Pd and Fe is about 1:1.

Take 2g of the newly prepared Pd-Fe/δ-Al ₂ O ₃ two-component catalyst, and use the evaluation conditions of Example 3 to evaluate the catalyst. The average yield after evaluation is: 1.92g/1g-1h.

Example 5:

Use 3.487g of LaCl ₃ 7H ₂ O to make 100ml of LaCl ₃ aqueous solution,

Take 7ml of the _PdCl2 solution prepared in Example 3, take 2.5ml of the FeCl3 solution, take 2.7ml of the newly prepared _LaCl3 solution _, mix them, adjust the pH value to 1.82, and make a mixed solution, and remove 7g of δ- _Al2O3 for _impregnation + α-Al ₂ O ₃ mixed crystal support for 5 hours, the solid was isolated, soaked with 8ml of the mixed lye prepared in Example 3 for 5 hours, filtered, washed with water until no Cl ^- could be detected, and dried. Reduction with H ₂ at 500°C for 4 hours to obtain a three-component catalyst of Pd-Fe-La/δ-Al ₂ O ₃ +α-Al ₂ O ₃ . The atomic ratio of La, Fe, and Pd is about 1:1:2.5.

Take 2 grams of the newly prepared Pd-Fe-La/δ-Al ₂ O ₃ +α-Al ₂ O ₃ three-component catalyst, and use the selection conditions in Example 3 to evaluate the catalyst. The average yield after evaluation was 2.33g/1g-1h, and the activity decreased slightly after 3 cycles.

Embodiment 6:

Take 7ml of PdCl ₂ solution, 2.5ml of FeCl ₃ solution, and 2.7ml of LaCl ₃ solution, mix them, and adjust the pH value to 1.82 to make a mixed solution, remove and impregnate 7g of the δ-Al ₂ O ₃ crystal carrier for 6 hours. After drying, take 10ml of the mixed lye prepared in Example 3, soak it at 70°C for 4 hours, filter, and wash with water until no Cl ^- can be detected. Reduction with H ₂ at 500°C for 4 hours, a Pd-Fe-La/δ-Al ₂ O ₃ catalyst was obtained, and the atomic ratio of La, Fe, and Pd was about 1:1:2.5.

Take 2g of the newly prepared Pd-Fe-La/δ-Al ₂ O ₃ catalyst, the evaluation conditions are the same as Example 3, the average yield after evaluation: 3.29g/1g-1h, cycle 3 times, the activity gradually increases.

Claims (8)

1. A catalyst for synthesizing oxalate, characterized in that it uses δ-Al ₂ O ₃ as a carrier and supports Pd, Fe and La active components. 2. The catalyst for synthesizing oxalate according to claim 1, characterized in that the atomic ratios of the active components Pd, Fe and La are 3-0.5:2-0.5:2-0.5, respectively. 3. The catalyst for synthesizing oxalate according to claim 1, characterized in that the pore structure of the δ-Al ₂ O ₃ carrier is: total pore volume (ml/g) 0.4-0.9; total pore volume Surface area (m ² /g) 60-100; average pore diameter (μ m) 0.03-0.05; apparent density (g/ml) 0.77-1.2; skeleton density (g/ml) 2.5-3.5. 4, the preparation method of the catalyst that is used for the synthesis of oxalic acid ester described in claim 1 is characterized in that comprising the steps: 1) Use Pd, Fe, La salts to prepare the impregnation solution according to the metering, pH=1-4.5; 2) Add δ-Al ₂ O ₃ into the dipping solution and soak for 2-8 hours; 3) Separation and drying, immersion in mixed alkali solution for 4-6 hours at 70°C, washing to remove negative ions, 4) Dry and reduce with H ₂ at 220-550°C for 3-5 hours. 5. The catalyst for synthesizing oxalate according to claim 1, characterized in that the preparation method of said δ-Al ₂ O ₃ carrier comprises: 1) Preparation of δ-Al ₂ O ₃ support from pseudoboehmite Pulverize pseudo-boehmite and pass through a 200-400 ^# mesh screen, add 1-3% of the powder amount to the powder and pass the same mesh number of graphite powder and 1-3% CaCO ₃ , then add 1-3% of the powder amount 45% dilute HNO ₃ (concentration is 1-3%), stir evenly, roll, extrude strips with a diameter of 2.5mm with an extruder, dry naturally for 4 hours, dry at 120°C, and follow the heating program Roasting; natural cooling to room temperature; 2) Preparation of δ-Al ₂ O ₃ support from AlCl ₃ 6H ₂ O React 5 parts of 8.6% AlCl ₃ ·6H ₂ O solution with 1 part of 1% NH ₄ OH solution, and react at 70°C under stirring, with a pH value of 7-8, leave it for 30 minutes, and filter with suction. Wash with water until no Cl ^- can be detected, dry at 120°C, add graphite, CaCO ₃ , dilute HNO3 successively according to the ratio of (1), roll, extrude into thin columnar strips with a diameter of 2.5 mm, and dry naturally for 5 hours. After drying at 120°C, roast according to the program; naturally cool to room temperature. 6. The method for preparing catalyst carrier δ-Al ₂ O ₃ for synthesizing oxalate according to claim 5, characterized in that the AlCl ₃ ·6H ₂ O can be Al ₂ (SO ₄ ) ₃ ·6H ₂ O or Al(NO ₃ ) ₃ ·6H ₂ O instead. 7. The method for preparing catalyst carrier δ-Al ₂ O ₃ for synthesizing oxalate according to claim 5, characterized in that the calcination heating program is as follows: Keep warm at 200°C for 20-40 minutes Keep warm at 250°C for 20-35 minutes Keep warm at 300°C for 2-4 hours Keep warm at 500°C for 20-40 minutes, keep warm at 600°C for 20-50 minutes, keep warm at 900°C for 4-9 hours. 8. The application method of the catalyst for the synthesis of oxalate according to claim 1, which is characterized in that it comprises the following steps: using a fixed bed device, and the reaction tube is a jacketed structure. The ratio of CO and RONO is controlled at 15-30 to 10-15 (volume ratio), the contact time is 0.5-3 seconds, the activation temperature of the catalyst is 120-140°C, and the reaction temperature is 100-130°C.

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