CN102350371B - Mesoporous molecular sieve catalyst and application of catalyst in synthesis of ethylene glycol monobutyl ether - Google Patents

Abstract

The invention discloses a mesoporous molecular sieve catalyst and an application of the catalyst in the synthesis of ethylene glycol monobutyl ether. The catalyst is prepared through treating a Al-MCM-41 mesoporous molecular sieve catalyst as raw powder, gamma-alumina as an adhesive, and nitric acid, polybasic carboxylic acid and polyethylene glycol 6000 as assistants, and molding through a band extrusion method. The catalyst of the invention, which has the advantages of good strength and strong overpressure resistance, still maintains a particulate state after being stirred for 5h in an intermittent stirring tank reactor, and no obvious fragmentation phenomenon appears. The catalyst of the present invention, which has a good catalytic activity and can be reused, allows the yield of ethylene glycol monobutyl ether to reach 36%.

Description

A kind of mesoporous molecular sieve catalyst and its application in the synthesis of ethylene glycol monobutyl ether

technical field

The invention relates to a mesoporous molecular sieve catalyst, and also relates to an application method of the mesoporous molecular sieve catalyst in synthesizing ethylene glycol monobutyl ether.

Background technique

In order to minimize the residual internal stress of the catalyst itself during preparation and use, the catalyst must be molded into particles of a certain shape and size during preparation, and this molding process is a key step in the industrial production of catalysts. There are many types of existing catalyst molding methods, common ones are compression molding, extrusion molding, rotational molding, spray molding, honeycomb molding, etc. (Ruthven D M., etc.J.Wiley-Interscience, New York , 1984), each of the above methods has different characteristics and uses.

Introducing appropriate additives in the catalyst molding process is an effective way to reduce the residual internal stress in the catalyst. Therefore, in recent years, the relationship between the properties of additives added in the molding process, the change of molding conditions, and the mechanical strength and pore structure of the catalyst has become increasingly popular. attention. Jiratov proposed that the peptization of the peptizer during the molding process is a function of the acid factor of Hammett, and found that the acidic peptizer can significantly increase the strength of the catalyst and improve the pore structure. Existing research results show that the viscosity of the binder component changes greatly with the concentration of safflower powder, and adding squat powder during the molding process is beneficial to molding (Li Y Y., etc.J.Powder Technology.2001(116) :85～96 ), but the relationship between the molding conditions and the chemical properties of the catalyst has not been reported in detail so far.

Ethylene glycol ether is an important derivative of ethylene oxide. Because of its ether group and hydroxyl group in its molecule, it is widely used as a solvent, anti-icing agent for jet fuel, brake fluid, and chemical intermediate because of its excellent performance. Glycol ethers mainly include ethylene glycol methyl (b, butyl) ether, diethylene glycol methyl (b, butyl) ether and triethylene glycol methyl (b, butyl) ether, etc. More than 50% of glycol ethers are used as solvents in various industrial processes, among which butyl glycol ether and its acetate have the largest demand.

Among the series of glycol ethers, ethylene glycol methyl ether is a good surface coating solvent and antifreeze additive for military jet fuel; ethylene glycol ether and its acetate are mainly used for protective coatings, dyes, resins, leather It can also be used as a cleaning agent for metal and glass; Ethylene glycol butyl ether and its acetate have good dispersibility in water and are widely used in water-based coatings. In addition, glycol ethers can also be used in many fields such as cosmetics industry, perfume industry, pharmaceutical industry, oilfield chemicals, etc. Various application fields have put forward higher and higher requirements on the properties and application performance of glycol ether series products. It is known that the most important factors affecting the molecular weight distribution of products are the structure of the reaction starting material and the properties of the catalyst. Therefore, in After determining the type of reaction starting material, the nature of the catalyst becomes a key factor in determining the molecular weight distribution of the product. Al-MCM-41 mesoporous molecular sieve catalyst can improve the properties and application performance of glycol ether series products by narrowing the molecular weight distribution of glycol ether.

Contents of the invention

The technical problem to be solved by the present invention is to provide a mesoporous molecular sieve catalyst, which not only has good compressive strength and impact resistance, but also has good catalytic activity. Another technical problem to be solved by the present invention is to provide an application method of the mesoporous molecular sieve catalyst in the synthesis of ethylene glycol monobutyl ether.

The mesoporous molecular sieve catalyst of the present invention is prepared by the following method:

① Weigh a certain amount of mesoporous molecular sieve Al-MCM-41 into the mortar;

②Add 30-40% gamma-alumina relative to the weight of mesoporous molecular sieve Al-MCM-4, mix well, grind and sieve;

③ According to the weight ratio of 10%-12%, 3%-5% and 5%-7% relative to the weight of mesoporous molecular sieve Al-MCM-41, weigh HNO ₃ , polycarboxylic acid and polyethylene glycol 6000 respectively. agent, and added to the mixed powder of step ②;

④ Stir all the above-mentioned raw materials evenly, put them into the extruder after mixing fully, and extrude them into strips with a diameter of 3-5mm and a length of 5-8mm, place them at room temperature for 2 hours, and dry them in the air. Dry it in a 100 ^o C drying oven for 10 hours, and put it into a muffle furnace for 550-600 degrees C to bake for 5 hours to obtain a finished shaped catalyst. The average pore diameter of the catalyst is about 4 nm, and the specific surface area is 800-1000 m ² ·g ^-1 .

The application of the mesoporous molecular sieve catalyst formed by the above method in the synthesis of ethylene glycol monobutyl ether:

The amount of catalyst used is 5% to 7% of the mass of ethylene glycol. Add ethylene glycol and catalyst to the autoclave under nitrogen protection. The initial pressure of the reaction is 0.4 MPa to 0.5 Mpa. , adding metered ethylene oxide (EO) in portions, when the reaction progresses until the pressure no longer drops significantly, stop the reaction and cool down to discharge the material.

The advantages of the present invention are: the present invention analyzes the Al-MCM-41 molecular sieve formed under different conditions, and systematically investigates the influence of the forming conditions on the catalyst acid content, pore structure, lateral pressure strength and the like. Tests have proved that the mesoporous molecular sieve catalyst prepared by this method has the best macroscopic physical properties, the maximum lateral pressure strength can reach 48N·cm ^-1 , the total acid content can reach 0.8201mmol·g ^-1 , and the acidity is weak to moderately strong. It has good strength and anti-shock performance. It can still maintain the state of particles after being stirred in a batch stirred tank reactor for 5 hours without obvious breakage. The catalyst of the invention has good catalytic activity in the reaction of synthesizing ethylene glycol monobutyl ether, and can be reused, and the yield of ethylene glycol monobutyl ether reaches 36%. When the amount of catalyst is 5%~7% of the mass of ethylene glycol, the reaction temperature is 110℃~120℃, and the initial reaction pressure is 0.4 MPa~0.5 Mpa, the average rate of the catalytic reaction reaches 2.604mol.h ^-1 .mol ^-1 .

Description of drawings

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is the XRD pattern of the catalyst of the present invention before molding.

Fig. 2 is an XRD pattern of the catalyst of the present invention after molding.

Fig. 3 is a SEM analysis diagram of the catalyst of the present invention before molding.

Fig. 4 is a SEM analysis diagram of the catalyst of the present invention after molding.

Fig. 5 is an analysis diagram of NH ₃ -TPD of the catalyst of the present invention before molding.

Fig. 6 is an analysis diagram of NH ₃ -TPD of the catalyst of the present invention before molding.

Figure 7 shows the effect of the amount of γ-alumina on the lateral compressive strength of the formed molecular sieve.

Fig. 8 is the correlative figure of reaction temperature and reaction rate in embodiment 3.

Figure 9 is a correlation diagram of initial pressure versus reaction rate in Example 4.

Fig. 10 is the correlative diagram of catalyst dosage to reaction rate in embodiment 5.

Detailed ways

Embodiment 1: the shaping of Al-MCM-41 mesoporous molecular sieve catalyst

Al-MCM-41 mesoporous molecular sieves were synthesized at the molar ratio n(TEOS):n(NaAlO ₂ ):n(CTAB):n(H ₂ O)=1.0:0.033:0.012:3.5:130. Dissolve a certain amount of NaAlO ₂ (about 0.7g) and cetyltrimethylammonium bromide CTAB (about 12g) in 600ml of deionized water at room temperature, add ethylenediamine, and adjust the pH of the system to 12 , and finally, 57ml of ethyl orthosilicate was added under stirring at a medium speed (300 rad/min), and reacted at 50°C for 7h. After the reaction, it was left to cool down to room temperature, crystallized and settled for about 15 hours, filtered with suction and washed with deionized water until neutral, and the solid was dried at 100°C for 12 hours. Then it was placed in a muffle furnace at 550°C for 6 hours to obtain Al-MCM-41 mesoporous molecular sieves.

Embodiment 2: the molding of Al-MCM-41 mesoporous molecular sieve catalyst

① Weigh a certain amount of mesoporous molecular sieve Al-MCM-41 into the mortar.

②Add γ-alumina, W (γ-alumina)=40% (Al-MCM-41), mix well, grind and sieve.

③ Weigh three additives, W (HNO ₃ )=10%, W (polycarboxylic acid)=3% and W (polyethylene glycol 6000)=5% into the mixed powder.

④ Stir evenly, put it into extruder and extrude into extruder to form pellets with a length of 5-8mm and a diameter of 3-5mm. Place them at room temperature for 2 hours, dry them in the air, and dry them in a drying oven at 100 ^o C for 10 hours at 550°C Calcined for 5 hours to obtain the finished shaped catalyst.

Accompanying drawing 1 and 2 are respectively the XRD pattern of Al-MCM-41 mesoporous molecular sieve catalyst before and after molding. It can be seen that d ₁₀₀ =3.425nm, d ₁₁₀ =1.463nm, and d ₂₀₀ =1.342nm before Al-MCM-41 is formed. After forming, d ₁₀₀ =3.221 nm, d ₁₁₀ =1.678 nm, d ₂₀₀ =1.252 nm. Compared with the sample before molding, although the distance between the mirrors becomes smaller and the thickness of the pore wall increases, the molding does not change the crystal structure of the catalyst, and still maintains the regular hexagonal mesoporous structure characteristics.

Figures 3 and 4 are the NH ₃ -TPD spectra of the Al-MCM-41 mesoporous molecular sieve catalyst before and after molding. It can be seen that the catalyst has a weak acid center, and the acid content of the catalyst after molding is 0.8201mmol·g ^-1 , which is higher than that before molding (0.70421mmol·g ^-1 ).

Accompanying drawing 5 and 6 are the SEM analysis to Al-MCM-41 mesoporous molecular sieve catalyst before and after forming respectively. It can be seen from the comparison that the molded Al-MCM-41 molecular sieve catalyst has larger particles and pores than the molded catalyst powder, which can improve the mass transfer and heat transfer of the reaction, which is beneficial to the catalytic reaction and has been easily separated from the final product of the reaction.

Figure 7 shows the effect of the amount of γ-alumina on the lateral compressive strength of the formed molecular sieve, from which it can be seen that when the amount of the binder is 30% to 40% of the catalyst, the compressive strength of the molecular sieve tends to the highest equilibrium value.

Example 3: The reaction rate of shaped Al-MCM-41 in the catalytic synthesis of ethylene glycol monobutyl ether (depending on the reaction temperature)

Add 1mol (a certain amount) of ethylene glycol into a high-pressure reactor equipped with a mechanical stirring device and a water cooling device, W (cat)%=5% (ethylene glycol) (the catalyst amount is 5% to 7% of ethylene glycol %), when heated to 140°C, 1mol ethylene oxide was added in batches, the initial pressure was 0.45Mpa, and the reaction rate of ethylene oxide was 2.756mol.h ^-1 .mol ^-1 .

It can be seen from accompanying drawing 8 that temperature has a great influence on the reaction rate, and choosing an appropriate temperature is beneficial to the improvement of product yield. At lower temperatures (less than 110°C), the reaction between ethylene glycol and EO is very slow; when the temperature is greater than 110°C, the reaction rate increases significantly with the increase of temperature, but with further increase of temperature, The increase rate gradually decreases. When the temperature is 120°C, there is already a high reaction rate. At the same time, if the reaction temperature is too high, the occurrence of side reactions will increase, and the color of the reaction product will become darker. This is due to the increase in the content of PEG in the by-product. , so 11°C to 120°C can be selected as the reaction temperature.

Example 4: The reaction rate of shaped Al-MCM-41 in the catalytic synthesis of ethylene glycol monobutyl ether (determined by the initial pressure)

Add 1mol ethylene glycol, W (cat)%=5~7% (ethylene glycol) to the high pressure reactor equipped with mechanical stirring device and water cooling device (catalyst amount is 5%~7% of ethylene glycol) , the reaction temperature is 110°C-120°C, 1mol ethylene oxide is added in batches, the initial pressure is 0.65Mpa, and the reaction rate of ethylene oxide is 3.132mol.h ^-1 .mol ^-1 .

As can be seen from accompanying drawing 9, the initial pressure of the reaction system has a greater influence on the reaction rate, and the reaction rate increases significantly with the increase of the system pressure, and the reaction rate does not increase when the value of the initial pressure increases to more than 0.50Mpa. Obviously, because the pressure of the reaction system is too high, the reaction is too violent, and the reaction temperature rises too fast, which will lead to an increase in side reactions. At the same time, too high pressure in the reaction system has high requirements on the reactor. Therefore, the initial pressure of the reaction is selected to be 0.45-0.50Mpa in this experiment.

Example 5: The reaction rate of shaped Al-MCM-41 in the catalytic synthesis of ethylene glycol monobutyl ether (determined by the amount of catalyst)

Add 100g of ethylene glycol, W (cat)%=10% (ethylene glycol) (the amount of catalyst is 9% to 10% of ethylene glycol) into the high-pressure reactor equipped with mechanical stirring device and water cooling device, and react The temperature is 110°C-120°C, 1mol ethylene oxide is added in batches, the initial pressure is 0.45Mpa, and the reaction rate of ethylene oxide is 3.476mol.h ^-1 .mol ^-1 .

As can be seen from accompanying drawing 10, with the increase of catalyst dosage, the reaction rate accelerates, and when the catalyst dosage is greater than 5%, the rate of increase in reaction rate slows down, and the synthesis and molding process of the catalyst require certain technical and economic costs , so the amount of catalyst should not be too large, and the best condition is to choose the amount of catalyst to be 5% to 7% of the mass of ethylene glycol.

Implementation Example 6: Yield of Ethylene Glycol Monomethyl Ether in Catalytic Synthesis of Ethylene Glycol Monobutyl Ether by Forming Al-MCM-41

Add 100g of ethylene glycol, W (cat)%=5% (ethylene glycol) (the amount of catalyst is 5% to 7% of ethylene glycol) into a high-pressure reactor equipped with a mechanical stirring device and a water cooling device, and react The temperature is 110°C-120°C, 1mol ethylene oxide is added in batches, the initial pressure is 0.45Mpa, and the yield of ethylene glycol monomethyl ether is 36%.

Implementation example 7: Activation and regeneration performance of shaped Al-MCM-41 mesoporous molecular sieve catalyst

After the ethylene glycol monobutyl ether synthesis reaction is completed, the catalyst in the product is filtered out by vacuum filtration, rinsed with deionized water, dried at 100°C, calcined at 600°C, weighed, and the catalyst recovery rate is calculated. The amount of catalyst used is 5% to 7% of the mass of ethylene glycol. At a temperature of 110°C to 120°C and an initial pressure of 0.4MPa to 0.5 Mpa, the average reaction rate of the catalyst to synthesize ethylene glycol monomethyl ether is 2.42 mol.h ^-1 .mol ^-1 .

Claims (2)

1. mesoporous molecular sieve catalyst, this catalyst are to adopt following methods to prepare moulding:

1. a certain amount of mesopore molecular sieve Al-MCM-41 of weighing puts into mortar;

2. add the gama-alumina with respect to mesopore molecular sieve Al-MCM-41 quality 30～40%, fully mix, grinding is sieved;

3. the weight ratio by relative mesopore molecular sieve Al-MCM-41 weight 10%～12%, 3%～5% and 5%～7% takes by weighing respectively HNO ₃, polybasic carboxylic acid and three kinds of auxiliary agents of Macrogol 6000, and join in the step mixed-powder 2.;

4. above-mentioned all raw materials are stirred, put into the banded extruder extruded moulding after fully mixing, place 2h under the room temperature, dry; The cylindrical catalyst intercepting that makes is long 5～8mm, the particle of diameter 3～5mm, 100 ^oThe dry 10h of C, 550～600 ℃ of roasting 5h obtain the preformed catalyst finished product, and this catalyst average pore size is 4nm, and specific area is 800～1000 m ²G ^-1

2. the application of mesoporous molecular sieve catalyst as claimed in claim 1 in the synthesizing glycol monobutyl ether: catalyst amount is 5%～7% of quality of glycol; ethylene glycol and catalyst are joined autoclave; nitrogen protection; the reaction initial pressure is 0.4 MPa～0.5 MPa; when temperature is increased to 110 ℃～120 ℃ of regulation reaction temperatures; gradation adds the oxirane (EO) of metering; when reaction proceeds to pressure and no longer obviously descends; stop to react cooling discharge, the Mean Speed of catalytic reaction reaches 2.604molh ^-1Mol ^-1

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