Method for in-situ preparation of mixed methylamine carbonate by continuous fixed-bed catalytic reaction and its application

Abstract

The present invention relates to a method for preparing mixed methylamine carbonate in situ by continuous fixed bed catalytic reaction and its application. A large-pore zeolite molecular sieve is loaded in a fixed bed as a catalyst, and ammonia produced by decomposition products such as carbonates is used as a gas phase ammonia source. A continuous feeding process is adopted with methanol gas phase to catalytically synthesize a methylamine mixture with trimethylamine as the main product, and further react with carbon dioxide in decomposition products such as carbonates to obtain methylamine carbonate (hydrogen). The product methylamine carbonate (hydrogen) can be further subjected to a base-catalyzed ring-opening reaction with an epoxy compound to prepare a quaternary ammonium (hydrogen) carbonate of mixed methylamine with better stability at room temperature. The methylamine carbonate (hydrogen) salt and the quaternary ammonium (hydrogen) carbonate of methylamine are used to manufacture polyurethane rigid foam plastic materials with good comprehensive performance. The present invention improves the safety and environmental protection of the ammonia source, the continuous synthesis process is efficient, and the product is used to manufacture polyurethane rigid foam plastics in a green and environmentally friendly manner.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemical industry, in particular to a method for preparing mixed methylamine ammonium carbonate in situ by continuous fixed-bed catalytic reaction and application thereof. Background Art

[0002] Methylamines, including monomethylamine, dimethylamine and trimethylamine, are widely used in medicine, pesticides, dyes, rubber vulcanization accelerators, synthetic feed additives and polycondensation catalysts. Methylamine bicarbonates and carbonates can be used as disinfectants and intermediates for preparing quaternary ammonium hydrogen carbonate and quaternary ammonium carbonate. Methylamine quaternary ammonium hydrogen carbonate and quaternary ammonium carbonate are used in antibacterial, sterilization and anti-corrosion coatings for metal substrates. Therefore, methylamine, methylamine carbonate and methylamine carbonate quaternary ammonium salt compounds have long been the focus of attention.

[0003] The main way to produce methylamine in modern chemical industry is to react methanol and ammonia at high temperature (about 400°C) and high pressure (>2.5MPa) in the gas phase in the presence of solid acid catalysts such as alumina, silicon oxide / alumina composites and molecular sieves with dehydration and aminating effects. Under the reaction conditions, a mixture of monomethylamine, dimethylamine and trimethylamine is generated, and distillation is usually used to separate and purify the methylamine mixture. However, since ammonia forms a complex azeotropic system with monomethylamine, dimethylamine and trimethylamine, in order to separate the methylamines, a very complicated large-scale device is required for distillation operation, which makes the energy consumption cost of the methylamine manufacturing process very high. For example, there is a detailed disclosure in the "Complete Collection of Revised Manufacturing Engineering Drawings" (published by Chemical Industry Co., Ltd. on April 25, 1974).

[0004] Previously, the demand for monomethylamine and trimethylamine other than dimethylamine was not large among methylamines. After separating dimethylamine from the reaction product, trimethylamine and monomethylamine were recycled into the reaction system for reuse. A method has been disclosed for suppressing the formation of trimethylamine and promoting the formation of dimethylamine by utilizing the shape selectivity of zeolite catalysts for amorphous solid acid catalysts governed by thermodynamic equilibrium. For example, a patent document (Japanese Patent Laid-Open No. 56-46846) using mordenite as a catalyst is disclosed; a method for producing dimethylamine by disproportionation reaction of trimethylamine is disclosed in Japanese Patent Laid-Open No. 57-169445; and a method for producing dimethylamine by disproportionation reaction of monomethylamine is disclosed in Japanese Patent Laid-Open No. 11-228507.

[0005] With the development of modern chemical industry, the consumption of trimethylamine has increased year by year. People have carried out corresponding work on how to improve the trimethylamine yield in the above-mentioned mixed amines. For example, the Chinese patent "Method for the manufacture of trimethylamine" (CN101062896A) provides a method for producing more trimethylamine by using a zeolite catalyst to reduce energy consumption costs in the process of manufacturing methylamine. The Chinese patent "A trimethylamine production device for the synthesis of cationic etherifying agents" (CN216472991U) discloses the use of rare earth solid acid catalysts to achieve a trimethylamine selectivity of 92%. The US patent (US4374273) uses aluminosilicate catalysts to prepare methylamine from methanol and ammonia by regulating SiO 2 / Al ratio, the content of monomethylamine, dimethylamine and trimethylamine in the mixed product can be regulated. The reaction product mixed methylamine in the aforementioned patents is often accompanied by 2-3% dimethyl ether as a by-product. US Patent (US4370503) points out a SiO 2 -Al 2 O 3 Composite catalyst, the catalyst containing SiO 2 The catalyst has the characteristics of less carbon deposition, high methanol conversion rate, trace amount of by-product dimethyl ether, and long service life. The Chinese patent "Methylamine catalyst and its preparation method" (ZL00129501.2) provides a SiO 2 -Al 2 O 3 The composition of SiO 2 The content is 18-22wt%, Al 2 O 3 When the content is 78-82wt%, the methanol conversion rate is nearly 100%, the product methylamine selectivity is high, the byproduct dimethyl ether and the like are generated in very small amounts, and it is not easy to coke under catalytic conditions. Certain zeolite and molecular sieve catalysts reported in the aforementioned patents show shape selectivity for the reaction of ammonia and methanol to generate methylamine. For the molecular sizes of the three methylamines, Abrams et al. (J. Catal., 1991, 127:9) simulated the behavior of trimethylamine in zeolite by isopropanol with the same molecular size as trimethylamine, indicating that large-pore mordenite, ZSM-5 and HY molecular sieves are conducive to the adsorption of trimethylamine, and in the methylamine mixture generated by the reaction of ammonia and methanol, the highest content of trimethylamine can be obtained in a controllable manner.

[0006] In order to prepare methylamine bicarbonate, carbonate and quaternary ammonium hydrogen carbonate and quaternary ammonium carbonate, the preparation of methylamine compounds must be solved first. The preparation methods of its carbonate and quaternary ammonium carbonate compounds generally adopt the reaction of methylamine compounds with carbonic acid gas to prepare methylamine bicarbonate or carbonate, and then carry out quaternization reaction to prepare methylamine quaternary ammonium hydrogen carbonate or quaternary ammonium carbonate.

[0007] However, so far, in various methylamine preparation methods, liquid ammonia is used as the raw material. Liquid ammonia is a compressible liquefied toxic gas. It is a colorless liquid under a certain pressure. It has a high pressure and becomes flammable and explosive under environmental influences. In particular, the potential danger of long-distance transportation limits the use of enterprises far away from the location of liquid ammonia raw materials. Therefore, the process route for producing methylamine using liquid ammonia as raw material has great potential risks in terms of safety, environmental protection and economy. Summary of the invention

[0008] Easily decomposable inorganic ammonium salts or organic amine compounds mainly include ammonium carbonate, ammonium bicarbonate, ammonium carbamate and urea aqueous solution. The theoretical decomposition reactions of these compounds are as follows (1) to (4):

[0009] (NH 4 ) 2 CO 3 →CO 2 +H 2 O+2NH 3 (1)

[0010] NH 4 HCO 3 →CO 2 +H 2 O+NH 3 (2)

[0011] NH 2 COONH 4 →CO 2 +2NH 3 (3)

[0012] (NH 2 ) 2 CO+H 2 O→CO 2 +2NH 3 (4)

[0013] Ammonium carbonate is a white or colorless translucent solid powder with the chemical composition of ammonium bicarbonate and hydroxyl ammonium carbamate. It starts to decompose at 30°C and decomposes violently at 55-66°C. Its decomposition products are ammonia, carbon dioxide and water. The gas emission is 700-980 mL / g, which is the highest among general chemical foaming agents. Ma Junyan et al. (Journal of Jilin University, 2015, 45(6):1804-1810) showed through TG experimental research that ammonium carbonate and ammonium carbamate start to decompose at room temperature, and the complete decomposition temperature is around 120°C. At the same temperature, the decomposition rate of ammonium carbamate is higher; the initial decomposition temperature of ammonium bicarbonate is about 80°C. At this temperature, ammonium bicarbonate only decomposes 1%, while ammonium carbamate decomposes 42% at 80°C and ammonium carbonate decomposes 30%. Compared with the other two ammonium salts, the decomposition rate of ammonium bicarbonate is very slow below 80°C, and it starts to decompose rapidly after exceeding 100°C, and it is completely decomposed at around 150°C. Urea is very soluble in water, with a solubility of 108.0 g / 100 mL in water at 20°C. In industry, a 50% mass concentration urea solution is usually used for catalytic hydrolysis to produce ammonia. At a suitable temperature of 130-160°C and a pressure of about 0.35-0.55 MPa, the catalytic urea aqueous solution is rapidly decomposed into a mixed gas product of ammonia, carbon dioxide and water vapor. This technology has been maturely applied to flue gas denitrification. Therefore, the ammonia in the above-mentioned compound decomposition products can be used to react with methanol as an ammonia source for preparing methylamine compounds. Under the conditions of solid acid catalyst, high temperature and appropriate pressure, ammonia and methanol can undergo the following methylation reaction of formula (5):

[0014]

[0015] In view of the shortcomings of safety and environmental protection in the existing methylamine (including monomethylamine, dimethylamine and trimethylamine) production technology, which uses liquid ammonia as an ammonia source, the present invention provides a method for preparing mixed methylamine carbonate in situ by continuous fixed-bed catalytic reaction and its application. By heating and decomposing ammonium carbonate, ammonium bicarbonate, ammonium carbamate and urea aqueous solution, the ammonia in the decomposition product is used as an ammonia source, and a suitable molecular sieve solid acid is used as a catalyst to react with methanol by a fixed-bed catalytic method to prepare a methylamine mixture, which will help to overcome the dangerous defects of the above-mentioned raw material liquid ammonia, and the process route has high economic efficiency.

[0016] While ammonium carbonate, ammonium bicarbonate, ammonium carbamate and urea aqueous solution are decomposed to produce ammonia, various raw materials simultaneously generate water and carbon dioxide in different molar ratios according to the decomposition products. Methanol and ammonia react at high temperature through a fixed bed reactor filled with the above catalyst to generate a methylamine mixture. The water atmosphere phase at high temperature will not cause the acidic site to be deactivated, and will not affect the catalytic activity of the methanol and ammonia reaction. The reaction product mixed gas leaves the high-temperature fixed bed reactor, is released by a back pressure valve, and is sent to a reactor that has been placed with a certain amount of water after cooling. The carbon dioxide in the mixed gas product can directly react with the mixed methylamine solution to form a salt, and synthesize mixed methylamine bicarbonate and carbonate.

[0017] Methylamine solution is more alkaline than ammonia water, and is easy to react with carbonic acid gas to form methylamine carbonate. For example, a 50wt% aqueous solution of methylamine mixture, when the content of trimethylamine in the mixed amine is 50wt%, its aqueous solution is still strong alkaline (pH>13), and carbonic acid gas reacts with mixed methylamine in this aqueous solution to easily form mixed methylamine bicarbonate. When the carbonic acid gas is excessive, a small amount of mixed methylamine carbonate will be generated. The specific reaction of mixed methylamine bicarbonate is as follows:

[0018]

[0019] Wherein R is methyl, and n=1, 2 or 3.

[0020] The present invention uses ammonia from the decomposition products of ammonium carbonate, ammonium bicarbonate, ammonium carbamate and urea aqueous solution as an ammonia source, which is mixed with gaseous methanol and introduced into a mordenite, ZSM-5, HY molecular sieve or SiO 2 -Al 2 O 3 The fixed bed reactor of the composite catalyst is used for methylamination reaction, and the methylamine mixed product, water vapor and carbon dioxide enter into a gas-liquid reactor into which metered water has been placed, and further completes the formation reaction of mixed methylamine carbonate.

[0021] The present invention adopts ammonia in thermal decomposition products such as ammonium carbonate, ammonium bicarbonate, ammonium carbamate and urea aqueous solution as an ammonia source to replace liquid ammonia, which greatly improves safety and environmental protection. The continuous fixed bed method catalytic reaction is used to prepare mixed methylamine, which has low reaction pressure, good economy, and can achieve continuous and controllable production. The carbon dioxide in the decomposition product and the methylamine mixture are then subjected to salt formation reaction to obtain mixed methylamine bicarbonate and mixed methylamine carbonate products. Since the mixed methylamine carbonate solution has the characteristic of being easy to decompose, it can be applied to the manufacture of polyurethane foam plastics, etc.

[0022] In particular, since the mixed methylamine carbonate (bicarbonate) solution is weakly alkaline, the mixed methylamine carbonate (bicarbonate) is easily decomposed at room temperature, the mixed methylamine carbonate (bicarbonate) solution is subjected to a ring-opening reaction with ethylene oxide and propylene oxide, and the mixed methylamine carbonate (bicarbonate) is further quaternized to prepare a quaternary ammonium carbonate (bicarbonate) mixture, and the stability of the mixed methylamine quaternary ammonium carbonate solution at room temperature can be effectively improved. The specific reaction is as follows:

[0023]

[0024] In the formula, R is a methyl group, n=1, 2 or 3; and R' is H or a methyl group.

[0025] Similarly, this type of quaternary ammonium carbonate (hydrogen) salt and quaternary ammonium carbonate (hydrogen) salt mixture is prone to thermal decomposition reaction when the temperature is above 50°C. Based on this characteristic, the quaternary ammonium carbonate solution mixed with methylamine can also be used in the manufacture of polyurethane foam plastics, etc.

[0026] The technical solution of the present invention is as follows:

[0027] A method for preparing mixed methylamine carbonate in situ by continuous fixed bed catalytic reaction comprises the following steps:

[0028] The decomposed ammonia source compound is used as a raw material, ammonia and carbon dioxide are obtained by thermal decomposition, methanol and ammonia are reacted by continuous fixed bed catalysis at high temperature to generate a methylamine mixture, and the methylamine mixture reacts with carbon dioxide and water to form a salt to obtain a mixed methylamine carbonate and / or methylamine bicarbonate.

[0029] According to the present invention, preferably, the decomposition ammonia source compound is an inorganic ammonium salt or an organic amine compound; further preferably, the inorganic ammonium salt is selected from ammonium carbonate and ammonium bicarbonate, and the organic amine is selected from ammonium carbamate and urea;

[0030] Preferably, urea is in the form of urea aqueous solution, and the mass concentration of the urea aqueous solution is 40% to urea saturated aqueous solution, more preferably 45% to 50% urea aqueous solution.

[0031] According to the present invention, preferably, the thermal decomposition conditions are as follows:

[0032] Ammonium carbonate, ammonium carbamate or ammonium bicarbonate is thermally decomposed at 70-100°C and 0.35-0.55MPa, more preferably at 80-90°C and 0.35-0.45MPa;

[0033] The urea aqueous solution is decomposed at 145 to 165° C. and 0.35 to 0.70 MPa, and more preferably at 155 to 165° C. and 0.45 to 0.70 MPa.

[0034] According to the present invention, preferably, the catalyst for the continuous fixed bed catalytic reaction is a mordenite catalyst, or ZSM-5, HY molecular sieve or SiO 2 -Al 2 O 3 Composition catalyst.

[0035] According to the present invention, preferably, the continuous fixed bed catalytic reaction conditions are 380-420° C. and 1.25-1.50 MPa, and more preferably the reaction temperature is 400-410° C. and the controlled pressure is 1.25-1.40 MPa.

[0036] According to the present invention, preferably, the molar ratio of ammonia to methanol feed is 1:1-1:1.5, more preferably 1:1-1:1.2.

[0037] According to the present invention, preferably, the temperature for the salt-forming reaction of the methylamine mixture with carbon dioxide and water is 35-40° C. and the pressure is <0.35 MPa.

[0038] According to the present invention, the mixed methylamine bicarbonate solution is further subjected to a ring-opening reaction with an epoxide, such as ethylene oxide, propylene oxide or epichlorohydrin, to quaternize the mixed methylamine bicarbonate to prepare a mixed methylamine carbonate quaternary ammonium hydrogen salt, which can effectively improve the stability of the mixed methylamine carbonate solution at room temperature.

[0039] According to the present invention, preferably, the temperature for the ring-opening reaction of the mixed methylamine carbonate quaternary ammonium salt solution and the epoxide is 35-60° C. and the pressure is <0.60 MPa;

[0040] Further preferably, when the epoxide is ethylene oxide, the reaction temperature and pressure are: 35-40°C and <0.35MPa;

[0041] When the epoxide is propylene oxide, the reaction temperature and pressure are 55-60°C and <0.60MPa.

[0042] According to the present invention, since the mixed methylamine carbonate solution has the characteristic of being easy to decompose, it can be applied to the manufacture of polyurethane foam plastics, etc. Similarly, the mixed methylamine carbonate quaternary ammonium salt is prone to thermal decomposition reaction when the temperature is higher than 50-60° C. Based on this characteristic, the mixed methylamine carbonate quaternary ammonium salt can also be used to manufacture polyurethane foam plastic materials.

[0043] According to the present invention, a device for in-situ preparation of mixed methylamine carbonate by continuous fixed-bed catalytic reaction is also provided, comprising: a methanol storage tank and a decomposition device, wherein the methanol storage tank is connected to a gas phase mixer via a liquid phase metering pump and a vaporizer in sequence, the decomposition device is connected to the gas phase mixer via a mass flow meter, the gas phase mixer is connected to the top of a fixed bed reactor, the bottom of the fixed bed reactor is connected to a first gas-liquid separator via a back pressure valve, the bottom of the first gas-liquid separator is connected to the gas-liquid reactor via a first liquid compression pump, the top of the first gas-liquid separator is connected to a second gas-liquid separator, the top of the second gas-liquid separator is connected to the gas-liquid reactor via a gas compression pump, and the bottom of the second gas-liquid separator is connected to the gas phase mixer via a second liquid compression pump.

[0044] According to the present invention, preferably, the number of the gas-liquid reactors is two and they are arranged in parallel. That is, the bottom of the first gas-liquid separator is connected to the first gas-liquid reactor and the second gas-liquid reactor respectively through the first liquid compression pump, and the top of the second gas-liquid reactor is connected to the first gas-liquid reactor and the second gas-liquid reactor respectively through the gas compression pump.

[0045] According to the present invention, preferably, the temperature of the first gas-liquid separator is 10°C, and the temperature of the second gas-liquid separator is -35°C.

[0046] According to the present invention, there is also provided a method for in-situ preparation of mixed methylamine carbonate by continuous fixed bed catalytic reaction using the above device, comprising the following steps:

[0047] The methanol in the methanol storage tank is fed into the vaporizer through a liquid-phase metering pump to complete gasification, and then fed into a gas-phase mixer, mixed with the ammonia source gas-phase material decomposed by the decomposition device, and then fed into a fixed-bed reactor loaded with a catalyst for methylamination reaction; the methylamination reaction product is discharged through a back pressure valve, and enters a first gas-liquid separator to separate the mixed methylamine gas-phase product and water from the unconverted ammonia and carbon dioxide gas for gas-liquid separation, the liquid-phase mixed methylamine / water is fed into a first gas-liquid reactor and a second gas-liquid reactor into which metering water has been placed through a first liquid compression pump for salt-forming reaction, the unconverted ammonia and carbon dioxide gas are separated again in the second gas-liquid separator, the liquid ammonia is fed into the gas-phase raw material mixer through a second liquid compression pump as a return material, and the carbon dioxide gas is pumped into the first gas-liquid reactor and the second gas-liquid reactor through a gas compression pump for salt-forming reaction.

[0048] According to the present invention, preferably, the temperature of the metered methanol entering the vaporizer is controlled at 80-120°C, and further preferably, the vaporization temperature is controlled at 85-90°C, thereby forming 0.30-0.40MPa of gaseous methanol, so as to facilitate transportation into the gas phase mixer; when urea aqueous solution is used as the decomposition ammonia source, the vaporization temperature of the methanol is controlled at 110-120°C, forming 0.60-0.75MPa of gaseous methanol, so as to facilitate transportation into the gas phase mixer. It is particularly important to note that when the methanol gas and the ammonia source gas phase are fed into the gas phase mixer, the pressure is adjusted in a timely manner to facilitate the implementation of the process coordination.

[0049] The raw materials described in the present invention, such as ammonium carbonate, ammonium carbamate or ammonium bicarbonate, are thermally decomposed in a thermal decomposition kettle at 70-100° C. and 0.35-0.55 MPa, and are continuously fed in gas phase by a mass flow meter in a manner of switching between two kettles, and are sent to a gas phase mixer to be mixed with methanol gas; the urea raw material can be in the form of an aqueous solution, and is catalytically hydrolyzed in a decomposition device, and the hydrolysis conditions are 145-165° C. and a pressure of 0.35-0.70 MPa, and the urea aqueous solution is catalytically decomposed into a mixed gas product of ammonia, carbon dioxide and water vapor, and is continuously fed in gas phase by a mass flow meter, and is sent to a gas phase mixer to be mixed with methanol gas.

[0050] According to the present invention, preferably, the decomposed ammonia source compound is ammonium carbonate, ammonium carbamate and 40% to urea saturated aqueous solution; the concentration of the urea aqueous solution is preferably 45% to 50% urea aqueous solution. Since ammonium carbonate and ammonium carbamate can be decomposed from room temperature, and the complete decomposition temperature is about 120°C, there is almost no reaction equilibrium, and it is easy to completely decompose, so it is more conducive to being used as an ammonia source reactant. Preferably, the thermal decomposition conditions of ammonium carbonate and ammonium carbamate are 80-90°C and 0.35 to 0.45MPa. The 50% urea aqueous solution is at 155 to 165°C and the pressure is about 0.45 to 0.70MPa, and the catalytic urea aqueous solution can be quickly and irreversibly decomposed into a mixed gas product of ammonia, carbon dioxide and water vapor.

[0051] The fixed bed reactor of the present invention can be loaded with a variety of catalysts. By selecting different molecular sieve catalysts with different Si / Al ratios, pore sizes, specific pore volumes, etc., the contents of different methylamines in the mixed methylamines can be effectively controlled. Preferably, large-pore mordenite, H-ZSM-5 or USY molecular sieve or SiO 2 -Al 2 O 3 The composition is used as a catalyst, and because of its large pore size, it is beneficial to the adsorption of trimethylamine, so that the mixed methylamine product has a higher trimethylamine content.

[0052] The gas phase reaction materials of the present invention, ammonia, carbon dioxide and water (anhydrous in the case of ammonium carbamate) and methanol (gas) are mixed in a certain molar ratio in a gas phase mixer and then fed into a gas phase mixer filled with large pore mordenite, H-ZSM-5, USY molecular sieve, or SiO 2 -Al 2 O 3 The fixed bed reactor of the composition is controlled at 380-420°C and 1.25-1.50MPa. Under this condition, ammonia and methanol react to generate monomethylamine, dimethylamine and trimethylamine. The mixed methylamine with high trimethylamine content is prepared by preferably large-pore ZSM-5 and USY molecular sieve, the preferred reaction temperature is 400-410°C, and the controlled pressure is 1.25-1.40MPa. At this time, the content of trimethylamine in the mixed methylamine is about 56%-71%.

[0053] When the feed molar ratio of ammonia to methanol of the present invention is 1:1-1:1.5, the methanol conversion rate is relatively high, reaching 85% to 99.5%; as the feed molar ratio of ammonia to methanol changes, the contents of various methylamines in the mixed methylamine change accordingly; preferably, the feed molar ratio of ammonia to methanol is 1:1 to 1:1.2, the methanol conversion rate is above 87%, and the trimethylamine content in the mixed methylamine after exiting the fixed bed reactor FR-1 is above 56%.

[0054] The mixed methylamine and other gaseous products prepared by the fixed bed reactor of the present invention are mixed with methylamine, water vapor, carbon dioxide and ammonia gas for complete reaction after passing through a back pressure valve, and enter the first gas-liquid separator under 10°C, condense and complete the gas-liquid separation of the methylamine mixed solution and the residual ammonia gas and carbon dioxide, and the condensed water and the mixed methylamine are sent to the gas-liquid reactor; the gaseous residual ammonia gas and carbon dioxide enter the low-temperature second gas-liquid separator at -35°C, condense and complete the gas-liquid separation of the residual ammonia and carbon dioxide, and the liquid ammonia is sent back to the gas phase mixer by the first liquid compression pump to participate in the circulation reaction, and the gaseous carbon dioxide is sent to the gas-liquid reactor by the gas compression pump, and further reacts to generate mixed methylamine bicarbonate or mixed methylamine carbonate. The preferred decomposed ammonia source compound is ammonium carbonate and ammonium carbamate and 50% urea aqueous solution, and the molar ratio of ammonia to carbon dioxide produced by decomposition is 2:1. When the ammonia conversion rate is about 50%, the main product obtained by the reaction of mixed methylamine and carbon dioxide is mixed methylamine bicarbonate, which is referred to as mixed methylamine carbonate in the present invention.

[0055] The mixed methylamine bicarbonate generation reaction in the gas-liquid reactor of the present invention is a slow reaction. Since the methylamine mixture is mainly composed of trimethylamine, in its relatively strong alkaline aqueous solution, the mixed methylamine and carbon dioxide are easily reacted to generate a mixed methylamine bicarbonate solution. Preferably, the temperature and pressure of the gas-liquid reactor are controlled to be: 35-40°C and <0.35MPa, respectively. Under this process condition, the mixed methylamine carbonate reaction is completed. Two gas-liquid reactors are configured in the whole device for switching feed. After the gas-liquid reaction is completed during the period, the pressure is balanced to 0.0MPa, and the mixed methylamine carbonate solution material is released.

[0056] The product mixed methylamine bicarbonate solution prepared by the present invention can be used to further prepare a mixed methylamine carbonate quaternary ammonium hydrogen salt solution. Since the mixed methylamine bicarbonate is easily decomposed at room temperature, it generally needs to be stored below 10°C. The mixed methylamine bicarbonate solution prepared above is further subjected to a ring-opening reaction with an epoxide, such as ethylene oxide, propylene oxide, or epichlorohydrin, in other low-pressure reaction devices to quaternize the mixed methylamine bicarbonate to prepare a mixed methylamine carbonate quaternary ammonium hydrogen salt, which can effectively improve the stability of the mixed methylamine carbonate solution at room temperature. Preferably, the epoxide is ethylene oxide or propylene oxide. The mixed methylamine carbonate quaternary ammonium hydrogen salt of the present invention is referred to as a mixed methylamine carbonate quaternary ammonium salt.

[0057] The specific preparation method of the mixed methylamine carbonate quaternary ammonium salt solution of the present invention can be: controlling a low-pressure reaction device to feed a certain amount of mixed methylamine carbonate solution, water, ethylene oxide or propylene oxide under a negative pressure of -0.10 to -0.20 MPa, and then controlling the reaction temperature and pressure to be 35 to 40° C. and <0.35 MPa (for reaction with ethylene oxide), or 55 to 60° C. and <0.60 MPa (for reaction with propylene oxide), respectively. Under these process conditions, the mixed methylamine carbonate quaternary ammonium salt reaction is completed to prepare the mixed methylamine carbonate quaternary ammonium salt solution.

[0058] Similarly, this type of mixed methylamine carbonate quaternary ammonium salt is prone to thermal decomposition reaction when the temperature is higher than 50-60°C. Based on this characteristic, the mixed methylamine carbonate quaternary ammonium salt can also be used to manufacture polyurethane foam plastic materials. Preferably, the mixed methylamine carbonate quaternary ammonium salt solution is prepared using ethylene oxide or propylene oxide, which can be used to manufacture rigid polyurethane foam materials with better performance.

[0059] The beneficial effects of the present invention are as follows:

[0060] 1. The method for preparing mixed methylamine carbonate in situ by continuous fixed-bed catalytic reaction provided by the present invention uses ammonium carbonate, ammonium carbamate and urea aqueous solution thermal decomposition products without separation, and the ammonia therein replaces liquid ammonia as an ammonia source, which changes the traditional technical route for preparing methylamine and has significant safety and environmental protection.

[0061] 2. The method for preparing mixed methylamine carbonate in situ by continuous fixed-bed catalytic reaction provided by the present invention is to use large-pore mordenite, or H-ZSM-5, or USY molecular sieve, or SiO 2 -Al 2 O 3 The composition is a catalyst, the reaction process conditions are high temperature and low pressure reaction, and the trimethylamine content in the prepared mixed methylamine is as high as more than 56%;

[0062] 3. The method for preparing mixed methylamine carbonate in situ by continuous fixed-bed catalytic reaction provided by the present invention, wherein the product from the fixed-bed reactor is condensed to separate the mixed methylamine / water from the unreacted ammonia / carbon dioxide, and the liquid phase mixed methylamine / water is sent to the gas-liquid reactor; the gas phase is further condensed to separate the unreacted ammonia from the carbon dioxide, wherein the unreacted ammonia is further involved in the reaction as a return material, and the carbon dioxide is sent to the gas-liquid reactor to react with the mixed methylamine to form a salt, thereby preparing mixed methylamine carbonate. Since the above-mentioned ammonium carbonate and other compounds decompose to produce ammonia and carbon dioxide with a fixed molar composition, the carbon dioxide can meet the needs of preparing mixed methylamine carbonate, and there is no need to introduce additional carbonic acid gas, which greatly simplifies the mixed methylamine carbonate method, improves production efficiency, and is easy to implement industrially by continuous method;

[0063] 4. The method for preparing mixed methylamine carbonate in situ by continuous fixed-bed catalytic reaction provided by the present invention, wherein the prepared mixed methylamine carbonate can be further introduced with ethylene oxide or propylene oxide, etc., to carry out base-catalyzed ring-opening reaction to prepare a mixed methylamine carbonate quaternary ammonium salt with better stability at room temperature;

[0064] 5. The method for preparing mixed methylamine carbonate in situ by continuous fixed-bed catalytic reaction provided by the present invention, the prepared mixed methylamine carbonate solution, and the mixed methylamine quaternary ammonium carbonate solution are used to manufacture polyurethane rigid foam materials, especially the quaternary ammonium carbonate mixture prepared by ethylene oxide, which can be used to manufacture polyurethane rigid foam materials with better performance. If used as a substitute for chlorofluoroalkane foaming agents, it will have great environmental benefits.

[0065] 6. The device for preparing mixed methylamine carbonate in situ by continuous fixed-bed catalytic reaction of the present invention has a simple structure, can realize continuous reaction, and is easy for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 This is a schematic diagram of the structure of the device for in-situ preparation of mixed methylamine carbonate by continuous fixed-bed catalytic reaction in Example 1;

[0067] Figure 2 is a gas chromatogram of the reaction mixture product from the fixed bed reactor in Example 2;

[0068] Figure 3 is a gas chromatogram of the reaction mixture product from the fixed bed reactor in Example 6;

[0069] Figure 4 is a gas chromatogram of the reaction mixture product from the fixed bed reactor in Example 11;

[0070] Figure 5 This is the infrared spectrum of the mixed methylamine carbonate (A1) synthesized product of Example 2;

[0071] Figure 6 The infrared spectrum of the synthetic product of Example 7, mixed methylamine (isopropyl alcohol) carbonate quaternary ammonium salt (B21);

[0072] Figure 7 The infrared spectrum of the synthetic product of Example 8, mixed methylamine (isopropyl alcohol) carbonate quaternary ammonium salt (B22);

[0073] Figure 8 The appearance photos of polyurethane rigid foam plastic bodies prepared by using A1, A2 and A3;

[0074] Fig. 9 These are appearance photos of polyurethane rigid foam bodies prepared using B3, B4, B5, and B6.

[0075] Among them: V01 methanol storage tank, MP01 liquid phase metering pump, RR01 decomposition device, RH01 vaporizer, MIX01 gas phase mixer, MM01 mass flow meter, FR01 fixed bed reactor, BP01 back pressure valve, GLS01 first gas-liquid separator, GLS02 second gas-liquid separator, LP01 first liquid compression pump, LP02 second liquid compression pump, CP02 gas compression pump, PR01 first gas-liquid reactor, PR02 second gas-liquid reactor. DETAILED DESCRIPTION

[0076] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings, but the scope of the present invention is not limited thereto.

[0077] Example 1

[0078] like Figure 1As shown, a device for preparing mixed methylamine carbonate in situ by continuous fixed-bed catalytic reaction comprises: a methanol storage tank V01 and a decomposition device RR01, wherein the methanol storage tank V01 is connected to a gas phase mixer MIX01 via a liquid phase metering pump MP01 and a vaporizer RH01 in sequence, the decomposition device RR01 is connected to the gas phase mixer MIX01 via a mass flow meter MM01, the gas phase mixer MIX01 is connected to the top of a fixed bed reactor FR01, the bottom of the fixed bed reactor FR01 is connected to a first gas-liquid separator GLS01 via a back pressure valve BP01, the bottom of the first gas-liquid separator GLS01 is connected to the gas-liquid reactor via a first liquid compression pump LP01, the top of the first gas-liquid separator GLS01 is connected to a second gas-liquid separator GLS02, the top of the second gas-liquid separator GLS02 is connected to the gas-liquid reactor via a gas compression pump CP02, and the bottom of the second gas-liquid separator GLS02 is connected to the gas phase mixer MIX01 via a second liquid compression pump LP02.

[0079] In this embodiment, there are two gas-liquid reactors, which are arranged in parallel. That is, the bottom of the first gas-liquid separator GLS01 is connected to the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02 respectively through the first liquid compression pump LP01, and the top of the second gas-liquid reactor PR02 is connected to the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02 respectively through the gas compression pump CP02. The decomposition device RR01 is a thermal decomposition kettle.

[0080] The temperature of the first gas-liquid separator GLS01 is 10°C, and the temperature of the second gas-liquid separator GLS02 is -35°C.

[0081] Example 2

[0082] The mixed methylamine carbonate was prepared by using the apparatus for preparing mixed methylamine carbonate in situ by continuous fixed bed catalytic reaction as described in Example 1. In this example, ammonium carbonate was used as the ammonia source and hydrogen-type mordenite was used as the catalyst.

[0083] 6.410 kg of high-purity industrial methanol was placed in a methanol storage tank V01, and 9.705 kg of industrial ammonium carbonate was placed in a thermal decomposition kettle RR01. The methanol was sent to the gasifier RH01 through a liquid phase metering pump MP01 and gasified at 85°C. The decomposition gas product of ammonium carbonate was measured by a mass flow meter MM01 under heating at 90-95°C. The feed mass ratio of methanol and ammonium carbonate decomposition gas was controlled to be about 1:1.51 (wherein the N / C molar ratio was 1:1). The methanol gas and the ammonium carbonate decomposition gas were sent together through a gas phase mixer MIX01 into a fixed bed reactor FR01 filled with synthetic hydrogen-type large-pore mordenite (low Si / Al value 4.10-6.00, pore size of about 0.7 nm, Zhuoran Environmental Protection Technology Co., Ltd.). The catalyst had been ammoniated in advance and preheated to 410°C. The pressure in the fixed bed reactor FR01 was controlled to be 1.25 MPa by a back pressure valve BP01.

[0084] The reaction mixture exiting the fixed bed reactor FR01 enters the first gas-liquid separator GLS01, and completes the gas-liquid separation of the mixed methylamine, water, residual ammonia and carbon dioxide at 10°C. The mixed methylamine aqueous solution is sent to the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02 via the first liquid compression pump LP01; the gaseous residual ammonia and carbon dioxide enter the low-temperature second gas-liquid separator GLS02 at -35°C, and the liquid ammonia is sent back to the gas phase mixer MIX01 through the second liquid compression pump LP02 for circulation reaction; the gaseous carbon dioxide is sent to the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02 via the gas compression pump CP02.

[0085] The reaction mixture out of the fixed bed reactor FR01 is monitored by online gas chromatography for the composition of the gas phase product, thereby achieving the control of the mixed methylamine ammonium carbonate salt solution product. The mixed methylamine and carbon dioxide materials entering the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02, and 1.800 kg of water are simultaneously fed into the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02, and the salt-forming reaction is carried out at 35-40°C and a pressure below 0.35 MPa. After all the materials are fed and the reaction is completed, the temperature is slowly lowered to below 25°C, and the vacuum is slowly released at a pressure of about 0.00 MPa to remove a small amount of unreacted carbon dioxide, and a clear and transparent mixed methylamine ammonium carbonate salt solution of 15.790 kg is obtained, and its mass concentration is 53.2%, which is recorded as A1.

[0086] Composition analysis of the product from fixed bed reactor FR01:

[0087] The fixed bed reactor product was detected by online gas chromatography. The chromatographic conditions are as follows: chromatographic column: (methylamine analytical column gas phase packed chromatographic column, specification: 3m*3mm*60-80 mesh, maximum operating temperature: 200℃), instrument conditions: vaporization chamber temperature 150℃, detector TCD temperature 150℃, column temperature 100℃; column front pressure: 0.10MPa; injection method: direct injection, internal standard method for quantification. The chromatographic analysis of the product is shown in Figure 2 The chromatographic analysis results of each component are shown in Table 1 below.

[0088] Table 1

[0089] Each component ammonia Monomethylamine Dimethylamine Trimethylamine Methanol water total Retention time 1.153 2.550 4.428 5.566 7.939 10.973 / Peak area% 17.381 5.952 5.403 24.057 2.652 44.536 99.981

[0090] Further calculations based on the composition analysis results of the product from the fixed bed reactor FR01 show that under this condition, the conversion rate of methanol is about 93%, the conversion rate of the reaction of decomposing ammonia is about 41%, and the ammonia is separated and recycled to participate in the reaction. (There may be a small amount of dimethyl ether in the product, which may be covered by the trimethylamine peak because it is difficult to separate from trimethylamine; carbon dioxide has no peak).

[0091] In the following, X% is the methanol conversion rate, Y% is the decomposed ammonia conversion rate, S 总 is the total methylamine selectivity, LHSV is the feed space velocity, and they are calculated according to formula (8), formula (9), formula (10) and formula (11) respectively.

[0092]

[0093]

[0094]

[0095]

[0096] According to the experimental summary and evaluation of the product analysis of the fixed bed reactor FR01, the results of the hydrogen-type mordenite catalyst under the process conditions are listed in the following Table 2:

[0097] Table 2

[0098]

[0099] Reaction conditions: T = 410 ° C, P = 1.25 MPa, LHSV = 1.5 h -1 The amount of returned liquid ammonia accounts for about 12.5wt% of the total feed amount.

[0100] Example 3: Preparation of mixed methylamine carbonate quaternary ammonium salt using the mixed methylamine carbonate prepared in Example 2

[0101] The mixed methylamine carbonate prepared in Example 2 can be further subjected to a ring-opening reaction with ethylene oxide to prepare a quaternary ammonium carbonate of mixed methylamine. The details are as follows:

[0102] 2.000 kg of the above-mentioned mixed methylamine carbonate solution A1 and 0.355 kg of water are taken and put into another 5.0 L low-pressure reactor under a negative pressure of -0.2 MPa, and 0.455 kg of ethylene oxide is gradually introduced. After stirring and reacting for 2.5 hours at 35-40°C and a pressure below 0.35 MPa, equilibrium is continued under this condition until the pressure is about 0.0 MPa, the reaction is stopped, and the temperature is slowly lowered to below 25°C. When the pressure is close to equilibrium with the atmospheric pressure, the vacuum is slowly released to remove a small amount of unreacted ethylene oxide, and 2.800 kg of a clear and transparent mixed methylamine carbonate quaternary ammonium salt solution with a mass concentration of 54.0% is obtained, which is recorded as B1.

[0103] Example 4: Application of mixed methylamine carbonate ammonium salt solution A1 in preparing polyurethane rigid foam plastics

[0104] The mixed methylamine ammonium carbonate solution A1 prepared in Example 2 is used to prepare polyurethane rigid foam plastics. The preparation method is as follows:

[0105] 50 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Co., Ltd.), 10 parts of polyether polyol 403 (Yantai Shunda Polyurethane Co., Ltd.), 1 part of foam leveler SH-493A (Hubei Xinsihai Chemical Co., Ltd.), 5 parts of mixed methylamine ammonium carbonate solution A1, 0.25 parts of cyclohexylamine and 0.005 parts of organic tin were mixed uniformly to obtain a uniform and transparent foam composition, and then 61.0 parts of polyisocyanate MDI (Wanhua Chemical PM-200) were added thereto, and further stirred uniformly to prepare a polyurethane rigid foam plastic.

[0106] Example 5: Application of quaternary ammonium carbonate solution B1 mixed with methylamine in preparing polyurethane rigid foam plastics

[0107] The mixed methylamine carbonate quaternary ammonium salt B1 prepared in Example 3 is used to prepare polyurethane rigid foam plastics, and the preparation method is as follows:

[0108] 30.0 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Company), 15.0 parts of polyester polyol CF-6320 (Nanjing Kangsude Chemical Co., Ltd.), 1.0 parts of foam stabilizer SH-493A (Hubei Xinsihai Chemical Company), 7.0 parts of quaternary ammonium carbonate solution B1 mixed with methylamine, 0.25 parts of cyclohexylamine and 0.005 parts of organic tin were mixed to obtain a uniform and transparent foam composition, and then 50.0 parts of polyisocyanate PAPI-27 (Dow, USA) were added thereto, and further stirred to obtain a polyurethane rigid foam plastic.

[0109] Example 6

[0110] This example provides a method for preparing carbonate using ammonium carbonate as an ammonia source and a large-pore USY molecular sieve as a catalyst by a continuous fixed bed in-situ catalytic reaction. The preparation steps are the same as those in Example 2, except that:

[0111] The fixed bed reactor FR01 is loaded with USY molecular sieve (relative crystallinity ≧90%, low Si / Al value 5.6-6.0, average pore size of about 0.75nm, Zhuoran Environmental Protection Technology Co., Ltd.); the amount of high-purity industrial methanol is 3.203kg, and the amount of industrial ammonium carbonate is 4.850kg; the catalyst in the fixed bed reactor FR01 is aminated in advance and preheated to 410°C, and the back pressure valve BP01 controls the pressure inside the fixed bed reactor FR01 to 1.25MPa.

[0112] After the unconverted ammonia is separated from the reactants exiting the fixed bed reactor FR01, the mixed methylamine, carbon dioxide and water enter the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02. At the same time, 0.900 kg of water is fed into the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02 to carry out salt-forming reaction at 35-40°C and a pressure below 0.35 MPa. After all the materials are fed and the reaction is completed, the temperature is slowly lowered to below 25°C, and the vacuum is slowly released at a pressure of nearly 0.00 MPa to remove a small amount of unreacted carbon dioxide, thereby obtaining 7.850 kg of a clear and transparent carbonate solution of mixed methylamine with a concentration of 52.4%, which is recorded as A2.

[0113] Composition analysis of the product from fixed bed reactor FR01:

[0114] The fixed bed reactor FR01 product was detected by online gas chromatography. The chromatographic conditions were the same as in Example 2. The chromatographic analysis of the product is shown in Figure 3 The chromatographic analysis results of each component are shown in Table 3 below.

[0115] Table 3

[0116] Each component ammonia Monomethylamine Dimethylamine Trimethylamine Methanol water total Retention time 1.154 2.550 4.429 5.567 7.939 10.972 / Peak area% 18.920 4.971 4.576 23.375 4.690 43.421 99.954

[0117] Further calculations based on the composition analysis results of the products from the fixed bed reactor FR01 show that under this condition, the conversion rate of methanol is about 90%, the conversion rate of the decomposition of ammonia is about 38%, and the ammonia is separated and recycled to participate in the reaction.

[0118] According to the experimental summary and evaluation of the product analysis of the fixed bed reactor FR01, the results of the large pore USY molecular sieve catalyst under the process conditions are listed in the following Table 4:

[0119] Table 4

[0120]

[0121] Reaction conditions: T = 410 ° C, P = 1.25 MPa, LHSV = 1.5 h -1 The amount of returned liquid ammonia accounts for about 13.1wt% of the total feed amount.

[0122] Example 7

[0123] The carbonate solution A2 of mixed methylamine obtained in Example 6 can be further subjected to a ring-opening reaction with ethylene oxide to prepare a quaternary ammonium carbonate of mixed methylamine. The details are as follows:

[0124] 2.000 kg of the carbonate solution A2 of the mixed methylamine obtained in Example 6 and 0.360 kg of water were taken and placed in another 5.0 L low-pressure reactor under a negative pressure of -0.2 MPa, and 0.430 kg of ethylene oxide was gradually introduced. After stirring and reacting for 2.5 hours at a pressure of less than 0.35 MPa and at 35-40 ° C, the reaction was continued to balance under this condition until the pressure reached about 0.0 MPa, the reaction was stopped, and the temperature was slowly lowered to below 25 ° C. When the pressure was close to equilibrium with the atmospheric pressure, the vacuum was slowly released to remove a small amount of unreacted ethylene oxide, and 2.780 kg of a clear and transparent quaternary ammonium carbonate solution of mixed methylamine was obtained, which had a concentration of 53.0%, recorded as B21.

[0125] Example 8

[0126] The carbonate solution A2 of mixed methylamine obtained in Example 6 can also be further subjected to a ring-opening reaction with propylene oxide to prepare a quaternary ammonium carbonate of mixed methylamine. The specific preparation reaction process is as follows:

[0127] Take 2.000kg of the mixed methylamine carbonate solution A2 obtained in Example 6 and 0.460kg of water, and under a negative pressure of -0.2MPa, enter another 5.0L low-pressure reactor, gradually send 0.565kg of propylene oxide, and stir the reaction at 55-60°C and a pressure lower than 0.60MPa for 5.5 hours, continue to balance under this condition until the pressure is about 0.0MPa, stop the reaction, slowly cool to about 45°C, remove a small amount of unreacted propylene oxide under a pressure of 80kPa, slowly release the vacuum, and discharging to obtain 3.020kg of a milky white slightly turbid mixed methylamine carbonate quaternary ammonium salt solution with a concentration of 53.3%, recorded as B22.

[0128] Example 9: Application of mixed methylamine ammonium carbonate solution in preparing polyurethane rigid foam plastics

[0129] The mixed methylamine carbonate solution A2 prepared in Example 6 is used to prepare polyurethane rigid foam plastics, and the preparation method is as follows:

[0130] 50 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Co., Ltd.), 10 parts of polyether polyol 403 (Yantai Shunda Polyurethane Co., Ltd.), 1 part of foam leveler SH-493A (Hubei Xinsihai Chemical Co., Ltd.), 5 parts of A2 solution, 0.25 parts of cyclohexylamine and 0.005 parts of organotin were mixed uniformly to obtain a uniform and transparent foam composition, and then 61.0 parts of polyisocyanate MDI (Wanhua Chemical PM-200) were added thereto, and further stirred uniformly to prepare a polyurethane rigid foam plastic.

[0131] Example 10: Application of quaternary ammonium carbonate solution mixed with methylamine in preparing polyurethane rigid foam plastics

[0132] The mixed methylamine carbonate quaternary ammonium salt solutions B21 and B22 prepared in Example 7 and Example 8 are used to prepare polyurethane rigid foam plastics. The preparation method is as follows:

[0133] 30.0 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Company), 15.0 parts of polyester polyol CF-6320 (Nanjing Kangsude Chemical Co., Ltd.), 1.0 parts of foam stabilizer SH-493A (Hubei Xinsihai Chemical Company), 7.0 parts of B21 or B22 solution, 0.25 parts of cyclohexylamine and 0.005 parts of organic tin were mixed uniformly to obtain a uniform, transparent foam composition, and then 50.0 parts of polyisocyanate PAPI-27 (Dow, USA) were added thereto, and further stirred uniformly to prepare a polyurethane rigid foam plastic.

[0134] Embodiment 11

[0135] This embodiment provides a method for preparing carbonate using ammonium carbonate as an ammonia source and H-type ZSM-5 molecular sieve as a catalyst by continuous fixed bed in-situ catalytic reaction. The preparation steps are the same as those in Example 2, except that:

[0136] The fixed bed reactor FR01 is loaded with H-type ZSM-5 molecular sieve (relative crystallinity>95%, low Si / Al value of 12.4, average pore size of about 0.55-0.60nm, Zhuoran Environmental Protection Technology Co., Ltd.); the amount of high-purity industrial methanol is 4.270kg, and the amount of industrial ammonium carbonate is 6.470kg; the catalyst in the fixed bed reactor FR01 is aminated in advance and preheated to 400°C, and BP01 controls the internal pressure of the fixed bed reactor FR01 to 1.30MPa.

[0137] After the unconverted ammonia is separated from the reactants exiting the fixed bed reactor FR01, the mixed methylamine, carbon dioxide and water enter the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02. At the same time, 1.200 kg of water is fed into the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02 to carry out salt-forming reaction at 35-40°C and a pressure below 0.35 MPa. After all the materials are fed and the reaction is completed, the temperature is slowly lowered to below 25°C, and the vacuum is slowly released at a pressure of nearly 0.00 MPa to remove a small amount of unreacted carbon dioxide, thereby obtaining 10.410 kg of a clear and transparent mixed methylamine ammonium carbonate salt solution with a mass concentration of 51.5%, which is recorded as A3.

[0138] Composition analysis of the product from fixed bed reactor FR01:

[0139] The fixed bed reactor product was detected by online gas chromatography. The chromatographic conditions were the same as in Example 2. The chromatographic analysis of the product is shown in Figure 4 The chromatographic analysis results of each component are shown in Table 5 below.

[0140] Table 5

[0141] Each component ammonia Monomethylamine Dimethylamine Trimethylamine Methanol water total Retention time 1.156 2.551 4.431 5.570 7.941 10.973 / Peak area% 18.859 3.682 9.154 20.847 5.078 42.366 99.987

[0142] Further calculations based on the composition analysis results of the products from the fixed bed reactor FR01 show that under this condition, the conversion rate of methanol is about 87%, the conversion rate of the decomposition of ammonia is about 36%, and the ammonia is separated and recycled to participate in the reaction.

[0143] According to the experimental summary and evaluation of the product analysis of the fixed bed reactor FR01, the results of the H-type ZSM-5 molecular sieve catalyst under the process conditions are listed in the following Table 6:

[0144] Table 6

[0145]

[0146] Reaction conditions: T = 400 ° C, P = 1.30 MPa, LHSV = 1.5h -1 The amount of returned liquid ammonia accounts for about 13.6wt% of the total feed amount.

[0147] Example 12: Preparation of quaternary ammonium carbonate of mixed methylamine using mixed methylamine carbonate

[0148] The ammonium carbonate of mixed methylamine prepared in Example 11 can be further subjected to a ring-opening reaction with ethylene oxide to prepare a quaternary ammonium carbonate of mixed methylamine. The details are as follows:

[0149] 2.000 kg of the carbonate solution A3 of the mixed methylamine prepared in Example 11 and 0.260 kg of water were taken and put into another 5.0 L low-pressure reactor under a negative pressure of -0.2 MPa, and 0.405 kg of ethylene oxide was gradually introduced. After stirring and reacting for 2.5 hours at 35-40° C. and a pressure lower than 0.35 MPa, equilibrium was continued under these conditions until the pressure was about 0.0 MPa, the reaction was stopped, and the temperature was slowly lowered to below 25° C. When the pressure was close to equilibrium with the atmospheric pressure, the vacuum was slowly released to remove a small amount of unreacted ethylene oxide, and 2.660 kg of a clear and transparent quaternary ammonium carbonate solution of mixed methylamine was obtained, and the concentration was 53.8%, recorded as B3.

[0150] Example 13: Application of mixed methylamine carbonate solution in preparing polyurethane rigid foam plastics

[0151] The mixed methylamine carbonate ammonium salt solution A3 prepared in Example 11 is used to prepare polyurethane rigid foam plastics, and the preparation method is as follows:

[0152] 50 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Co., Ltd.), 10 parts of polyether polyol 403 (Yantai Shunda Polyurethane Co., Ltd.), 1 part of foam leveler SH-493A (Hubei Xinsihai Chemical Co., Ltd.), 5 parts of ammonium carbonate solution A3 mixed with methylamine, 0.25 parts of cyclohexylamine and 0.005 parts of organotin were mixed to obtain a uniform and transparent foam composition, and then 61.0 parts of polyisocyanate MDI (Wanhua Chemical PM-200) were added thereto, and further stirred to obtain a polyurethane rigid foam plastic.

[0153] Example 14: Application of quaternary ammonium carbonate solution mixed with methylamine in preparing polyurethane rigid foam plastics

[0154] The mixed methylamine carbonate quaternary ammonium salt solution B3 prepared in Example 12 is used to prepare polyurethane rigid foam plastics. The preparation method is as follows:

[0155] 30.0 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Co., Ltd.), 15.0 parts of polyester polyol CF-6320 (Nanjing Kangsude Chemical Co., Ltd.), 1.0 parts of foam stabilizer SH-493A (Hubei Xinsihai Chemical Co., Ltd.), 7.0 parts of quaternary ammonium carbonate B3 mixed with methylamine, 0.25 parts of cyclohexylamine and 0.005 parts of organic tin were mixed to obtain a uniform and transparent foam composition, and then 50.0 parts of polyisocyanate PAPI-27 (Dow, USA) were added thereto, and further stirred to obtain a polyurethane rigid foam plastic.

[0156] Embodiment 15

[0157] This embodiment provides a method of using ammonium carbonate as an ammonia source and SiO 2 -Al 2 O 3 The composition is a catalyst, and a method for preparing carbonate by continuous fixed bed in-situ catalytic reaction is used. The preparation steps are the same as those in Example 2, except that:

[0158] Fixed bed reactor FR01 filled with SiO 2 -Al 2 O 3 Composition (cylindrical 5×5 mm particles, SiO 2 / Al 2 O 3 The weight ratio is 22 / 78 and the specific surface area is 306m 2 / g, specific pore volume is 0.89mL / g, homemade); the amount of high-purity industrial methanol is 2.565kg, and the amount of industrial ammonium carbonate is 3.880kg; the catalyst in the fixed bed reactor FR01 is aminated in advance and preheated to 410°C, and the back pressure valve BP01 controls the pressure inside the fixed bed reactor FR01 to 1.40MPa.

[0159] After the unconverted ammonia is separated from the reactants exiting the fixed bed reactor FR01, the mixed methylamine, carbon dioxide and water enter the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02. At the same time, 1.120 kg of water is fed into the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02 to carry out salt-forming reaction at 35-40°C and a pressure below 0.35 MPa. After all the materials are fed and the reaction is completed, the temperature is slowly lowered to below 25°C, and the vacuum is slowly released at a pressure of nearly 0.00 MPa to remove a small amount of unreacted carbon dioxide, thereby obtaining 6.780 kg of a clear and transparent mixed methylamine ammonium carbonate salt solution with a concentration of 51.4%, which is recorded as A4.

[0160] Composition analysis of the product from fixed bed reactor FR01:

[0161] The product of the fixed bed reactor FR01 was detected by online gas chromatography. The chromatographic conditions were the same as those in Example 2. The chromatographic analysis results of each component are shown in Table 7 below.

[0162] Table 7

[0163] Each component ammonia Monomethylamine Dimethylamine Trimethylamine Methanol water total Retention time 1.155 2.550 4.430 5.570 7.940 10.971 / Peak area% 15.950 7.317 8.486 21.616 0.531 46.088 99.988

[0164] Further calculations based on the composition analysis results of the products from the fixed bed reactor FR01 show that under this condition, the conversion rate of methanol is about 98.6%, the conversion rate of the decomposition of ammonia is about 45.6%, and the ammonia is separated and recycled to participate in the reaction.

[0165] The experimental summary of the product analysis of the fixed bed reactor FR01 showed that the SiO2 -Al 2 O 3 The results of the composite catalyst under the process conditions are listed in Table 8 below:

[0166] Table 8

[0167]

[0168] Reaction conditions: T = 410 ° C, P = 1.40 MPa, LHSV = 1.5h -1 The amount of returned liquid ammonia accounts for about 11.5wt% of the total feed amount.

[0169] Example 16: Preparation of mixed methylamine carbonate quaternary ammonium salt using mixed methylamine carbonate:

[0170] The carbonate of mixed methylamine prepared in Example 15 can be further subjected to a ring-opening reaction with ethylene oxide to prepare a quaternary ammonium carbonate of mixed methylamine. The details are as follows:

[0171] 2.000 kg of the above-mentioned mixed methylamine carbonate solution A4 and 0.470 kg of water were taken and put into another 5.0 L low-pressure reactor under a negative pressure of -0.2 MPa, and 0.475 kg of ethylene oxide was gradually introduced. After stirring and reacting for 2.5 hours at 35-40° C. and a pressure lower than 0.35 MPa, equilibrium was continued under this condition until the pressure was about 0.0 MPa, the reaction was stopped, and the temperature was slowly lowered to below 25° C. When the pressure was close to equilibrium with the atmospheric pressure, the vacuum was slowly released to remove a small amount of unreacted ethylene oxide, and 2.940 kg of a clear and transparent mixed methylamine carbonate quaternary ammonium salt solution with a concentration of 51.0% was obtained, which was recorded as B4.

[0172] Example 17: Application of mixed methylamine carbonate solution in preparing polyurethane rigid foam plastics

[0173] The mixed methylamine carbonate solution A4 prepared in Example 15 is used to prepare polyurethane rigid foam plastics. The specific preparation method is as follows:

[0174] 50 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Co., Ltd.), 10 parts of polyether polyol 403 (Yantai Shunda Polyurethane Co., Ltd.), 1 part of foam leveler SH-493A (Hubei Xinsihai Chemical Co., Ltd.), 5 parts of ammonium carbonate solution A4 mixed with methylamine, 0.25 parts of cyclohexylamine and 0.005 parts of organic tin were mixed uniformly to obtain a uniform and transparent foam composition, and then 61.0 parts of polyisocyanate MDI (Wanhua Chemical PM-200) were added thereto, and further stirred uniformly to prepare a polyurethane rigid foam plastic.

[0175] Example 18: Application of quaternary ammonium carbonate solution mixed with methylamine in the preparation of polyurethane rigid foam plastics

[0176] The mixed methylamine carbonate quaternary ammonium salt solution B4 prepared in Example 16 is used to prepare polyurethane rigid foam plastics. The specific preparation method is as follows:

[0177] 30.0 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Co., Ltd.), 15.0 parts of polyester polyol CF-6320 (Nanjing Kangsude Chemical Co., Ltd.), 1.0 parts of foam stabilizer SH-493A (Hubei Xinsihai Chemical Co., Ltd.), 7.0 parts of quaternary ammonium carbonate B4 mixed with methylamine, 0.25 parts of cyclohexylamine and 0.005 parts of organic tin were mixed to obtain a uniform and transparent foam composition, and then 50.0 parts of polyisocyanate PAPI-27 (Dow, USA) were added thereto, and further stirred to obtain a polyurethane rigid foam plastic.

[0178] Embodiment 19

[0179] This embodiment provides a method for using ammonia in the thermal decomposition product of ammonium carbamate as an ammonia source and SiO 2 -Al 2 O 3 The composition is a catalyst, and a method for preparing carbonate by continuous fixed bed in-situ catalytic reaction is used. The preparation steps are the same as those in Example 2, except that:

[0180] Fixed bed reactor FR01 filled with SiO 2 -Al 2 O 3 composition (same as Example 15); the amount of high-purity industrial methanol used is 2.565 kg, and the amount of industrial-grade ammonium carbamate (99%) used is 3.154 kg; the catalyst in the fixed bed reactor FR01 is aminated in advance and preheated to 410°C, and the back pressure valve BP01 controls the pressure in the fixed bed reactor FR01 to 1.40 MPa.

[0181] After the unconverted ammonia is separated from the reactants exiting the fixed bed reactor FR01, the mixed methylamine, carbon dioxide and water are fed into the reactor PR03-1. At the same time, 1.720 kg of water is fed into the reactor PR03-1 to carry out salt-forming reaction at 35-40°C and a pressure below 0.35 MPa. After all the materials are fed and the reaction is completed, the temperature is slowly lowered to below 25°C. The vacuum is slowly released at a pressure of nearly 0.00 MPa to remove a small amount of unreacted carbon dioxide, and 6.670 kg of a clear and transparent mixed methylamine ammonium carbonate salt solution is obtained, with a mass concentration of 52.5%, recorded as A5.

[0182] Composition analysis of the product from fixed bed reactor FR01:

[0183] The product of the fixed bed reactor FR01 was detected by online gas chromatography. The chromatographic conditions were the same as those in Example 2. The chromatographic analysis results of each component are shown in Table 9 below.

[0184] Table 9

[0185] Each component ammonia Monomethylamine Dimethylamine Trimethylamine Methanol water total Retention time 1.155 2.550 4.430 5.570 7.940 10.971 / Peak area% 18.731 8.738 10.135 25.640 0.224 36.530 99.998

[0186] Further calculations based on the composition analysis results of the product from the fixed bed reactor FR01 show that under this condition, the conversion rate of methanol is about 99.5%, the conversion rate of the decomposition of ammonia is about 46.0%, and the ammonia is separated and recycled to participate in the reaction.

[0187] The experimental summary of the product analysis of the fixed bed reactor FR01 showed that the SiO 2 -Al 2 O 3 The results of the composite catalyst under the process conditions are listed in Table 10 below:

[0188] Table 10

[0189]

[0190] Reaction conditions: T = 410 ° C, P = 1.40 MPa, LHSV = 1.5h -1 The amount of returned liquid ammonia accounts for about 12.9wt% of the total feed amount.

[0191] Example 20: Preparation of mixed methylamine carbonate quaternary ammonium salt using mixed methylamine carbonate:

[0192] The carbonate of mixed methylamines obtained in Example 19 can be further subjected to a ring-opening reaction with ethylene oxide to prepare a quaternary ammonium carbonate of mixed methylamines. The details are as follows:

[0193] Take 2.000kg of the above-mentioned mixed methylamine carbonate ammonium salt A5 aqueous solution and 0.450kg of water, under a negative pressure of -0.2MPa, into another 5.0L low-pressure reactor, gradually introduce 0.490kg of ethylene oxide, and stir the reaction at 35-40℃ and a pressure lower than 0.35MPa for 2.5 hours, continue to balance under this condition until the pressure is about 0.0MPa, stop the reaction, slowly cool to below 25℃, and when the pressure is close to equilibrium with the atmospheric pressure, slowly release the vacuum to remove a small amount of unreacted ethylene oxide, and obtain 2.930kg of a clear and transparent mixed methylamine carbonate quaternary ammonium salt aqueous solution with a mass concentration of 52.3%, recorded as B5.

[0194] Example 21: Application of mixed methylamine carbonate solution in preparing polyurethane rigid foam plastics

[0195] The mixed methylamine carbonate solution A5 prepared in Example 19 is used to prepare polyurethane rigid foam plastics. The specific preparation method is as follows:

[0196] 50 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Co., Ltd.), 10 parts of polyether polyol 403 (Yantai Shunda Polyurethane Co., Ltd.), 1 part of foam leveler SH-493A (Hubei Xinsihai Chemical Co., Ltd.), 5 parts of ammonium carbonate solution A5 mixed with methylamine, 0.25 parts of cyclohexylamine and 0.005 parts of organotin were mixed to obtain a uniform and transparent foam composition, and then 61.0 parts of polyisocyanate MDI (Wanhua Chemical PM-200) were added thereto, and further stirred to obtain a polyurethane rigid foam plastic.

[0197] Example 22: Application of quaternary ammonium carbonate solution mixed with methylamine in the preparation of polyurethane rigid foam plastics

[0198] The mixed methylamine carbonate quaternary ammonium salt solution B5 prepared in Example 20 is used to prepare polyurethane rigid foam plastics. The specific preparation method is as follows:

[0199] 30.0 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Co., Ltd.), 15.0 parts of polyester polyol CF-6320 (Nanjing Kangsude Chemical Co., Ltd.), 1.0 parts of foam stabilizer SH-493A (Hubei Xinsihai Chemical Co., Ltd.), 7.0 parts of quaternary ammonium carbonate B5 mixed with methylamine, 0.25 parts of cyclohexylamine and 0.005 parts of organic tin were mixed to obtain a uniform and transparent foam composition, and then 50.0 parts of polyisocyanate PAPI-27 (Dow, USA) were added thereto, and further stirred to obtain a polyurethane rigid foam plastic.

[0200] Embodiment 23

[0201] This embodiment provides a method for catalytic hydrolysis of urea in a urea catalytic hydrolysis reactor using a 50% urea aqueous solution, ammonia in the gas phase product as an ammonia source, and SiO 2 -Al 2 O 3 The composition is a catalyst, and a method for preparing a quaternary ammonium carbonate salt by continuous fixed bed in-situ catalytic reaction is used. The preparation steps are the same as those in Example 2, except that:

[0202] Fixed bed reactor FR01 filled with SiO 2 -Al 2 O 3composition (same as Example 15); 3.200 kg of high-purity industrial methanol and 6.010 kg of 50% by weight urea aqueous solution, the urea aqueous solution is catalytically hydrolyzed in the decomposition device RR01, and the gaseous product is fed; the catalyst in the fixed bed reactor FR01 is aminated in advance and preheated to 410°C, and the back pressure valve BP01 controls the pressure in the fixed bed reactor FR01 to 1.40 MPa.

[0203] After the reactants from the fixed bed reactor FR01 are separated from the unconverted ammonia, the mixed methylamine, carbon dioxide and water enter the first gas-liquid reactor PR01 and the second gas-liquid reactor PR02. Since the water content in the gas phase product of the urea hydrolysis reaction can reach 35wt%, the gas phase product is accompanied by water enough to dilute the mixed methylamine solution. The salt formation reaction is carried out at 35-40℃ and a pressure below 0.35MPa. After all the materials are fed and the reaction is completed, the temperature is slowly lowered to below 25℃. The vacuum is slowly released at a pressure of about 0.00MPa to remove a small amount of unreacted carbon dioxide, and a clear and transparent mixed methylamine ammonium carbonate salt solution of 8.290kg is obtained, with a mass concentration of 52.8%, which is recorded as A6.

[0204] Composition analysis of the product from fixed bed reactor FR01:

[0205] The product of the fixed bed reactor FR01 was detected by online gas chromatography. The chromatographic conditions were the same as those in Example 2. The chromatographic analysis results of each component are shown in Table 11 below.

[0206] Table 11

[0207] Each component ammonia Monomethylamine Dimethylamine Trimethylamine Methanol water total Retention time 1.155 2.550 4.430 5.570 7.940 10.971 / Peak area% 13.096 6.283 7.190 17.630 0.220 55.521 99.940

[0208] Further calculations based on the composition analysis results of the product from the fixed bed reactor FR01 show that under this condition, the conversion rate of methanol is about 99.3%, the conversion rate of the decomposition of ammonia is about 46.2%, and the ammonia is separated and recycled to participate in the reaction.

[0209] The experimental summary of the product analysis of the fixed bed reactor FR01 showed that the SiO 2 -Al 2 O 3 The results of the composite catalyst under the process conditions are listed in Table 12 below:

[0210] Table 12

[0211]

[0212] Reaction conditions: T = 410 ° C, P = 1.40 MPa, LHSV = 1.5h -1 The amount of returned liquid ammonia accounts for about 9.9wt% of the total feed amount.

[0213] Example 24: Preparation of quaternary ammonium carbonate of mixed methylamine using mixed methylamine carbonate

[0214] The ammonium carbonate salt of mixed methylamine prepared in Example 23 can be further subjected to a ring-opening reaction with ethylene oxide to prepare a quaternary ammonium carbonate salt of mixed methylamine. The details are as follows:

[0215] 2.000 kg of the mixed methylamine carbonate solution A6 prepared in Example 23 and 0.480 kg of water were taken and placed in another 5.0 L low-pressure reactor under a negative pressure of -0.2 MPa. 0.492 kg of ethylene oxide was gradually introduced. After stirring and reacting for 2.5 hours at 35-40° C. and a pressure below 0.35 MPa, equilibrium was continued under these conditions until the pressure was about 0.0 MPa, the reaction was stopped, and the temperature was slowly lowered to below 25° C. When the pressure was close to equilibrium with the atmospheric pressure, the vacuum was slowly released to remove a small amount of unreacted ethylene oxide, and 2.970 kg of a clear and transparent mixed methylamine carbonate quaternary ammonium salt solution was obtained with a mass concentration of 52.0%, recorded as B61.

[0216] Embodiment 25,

[0217] Similarly, the mixed methylamine ammonium carbonate salt prepared in Example 23 can also be further subjected to a ring-opening reaction with propylene oxide to prepare a mixed methylamine carbonate quaternary ammonium salt. The specific preparation reaction process is as follows:

[0218] 2.000 kg of the mixed methylamine carbonate solution A6 prepared in Example 23 and 0.600 kg of water were taken and placed in another 5.0 L low-pressure reactor under a negative pressure of -0.2 MPa. 0.650 kg of propylene oxide was gradually introduced. After stirring and reacting for 5.5 hours at 55-60 ° C and a pressure lower than 0.60 MPa, equilibrium was continued under these conditions until the pressure was about 0.0 MPa, the reaction was stopped, and the temperature was slowly lowered to about 45 ° C. A small amount of unreacted propylene oxide was removed under a pressure of 80 kPa, and the vacuum was slowly released to obtain 3.245 kg of a milky white slightly turbid mixed methylamine carbonate quaternary ammonium salt solution having a mass concentration of 52.4%, recorded as B62.

[0219] Example 26: Application of mixed methylamine carbonate solution in preparing polyurethane rigid foam plastics

[0220] The mixed methylamine carbonate solution A6 prepared in Example 23 is used to prepare polyurethane rigid foam plastics. The specific preparation method is as follows: 50 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Co., Ltd.), 10 parts of polyether polyol 403 (Yantai Shunda Polyurethane Co., Ltd.), 1 part of foam leveler SH-493A (Hubei Xinsihai Chemical Co., Ltd.), 5 parts of mixed methylamine ammonium carbonate solution A6, 0.25 parts of cyclohexylamine and 0.005 parts of organic tin are mixed evenly to obtain a uniform and transparent foam composition, and then 61.0 parts of polyisocyanate MDI (Wanhua Chemical PM-200) are added thereto, and further stirred evenly to prepare polyurethane rigid foam plastics.

[0221] Example 27: Application of quaternary ammonium carbonate solution mixed with methylamine in preparing polyurethane rigid foam plastics:

[0222] The mixed methylamine carbonate quaternary ammonium salt solutions B61 and B62 prepared in Example 24 and Example 25 are used to prepare polyurethane rigid foam plastics. The specific preparation method is as follows:

[0223] 30.0 parts (by weight, the same below) of polyether polyol 4110 (Yantai Shunda Polyurethane Company), 15.0 parts of polyester polyol CF-6320 (Nanjing Kangsude Chemical Co., Ltd.), 1.0 parts of foam stabilizer SH-493A (Hubei Xinsihai Chemical Company), 7.0 parts of quaternary ammonium carbonate of mixed methylamine B61 or B62, 0.25 parts of cyclohexylamine and 0.005 parts of organic tin are mixed uniformly to obtain a uniform, transparent foam composition, and then 50.0 parts of polyisocyanate PAPI-27 (Dow, USA) are added thereto, and further stirred uniformly to prepare a polyurethane rigid foam plastic.

[0224] In order to better understand the specific effects of the mixed methylamine carbonate solution and the mixed methylamine quaternary ammonium carbonate solution prepared by the present invention in preparing polyurethane rigid foam plastics, a comparative experiment of preparing polyurethane rigid foam plastics with 141B was carried out according to the same polyurethane rigid foam formula.

[0225] Comparative Example 1:

[0226] The polyurethane rigid foam plastics were prepared with 141B using the combination of polyether 4110 / 403 and polyisocyanate MDI (Wanhua Chemical PM-200) as the black material, and compared with the aforementioned various foaming systems, as follows:

[0227] The foaming agent 141B is used to prepare polyurethane rigid foam plastic. The preparation method is the same as "Application of mixed methylamine carbonate solution to prepare polyurethane rigid foam plastic" in Example 4. The amount of 141B is 12 parts, and a polyurethane rigid foam plastic is prepared, which is recorded as C.

[0228] Comparative Example 2:

[0229] The polyurethane rigid foam plastics were prepared with 141B using the combination of polyether 4110 / 403 and polyisocyanate MDI (Wanhua Chemical PM-200) as the black material, and compared with the aforementioned various foaming systems, as follows:

[0230] The foaming agent 141B is used to prepare polyurethane rigid foam plastic. The preparation method is the same as that in Example 5 "Application of quaternary ammonium carbonate solution mixed with methylamine to prepare polyurethane rigid foam plastic". The amount of 141B is 12 parts, and a polyurethane rigid foam plastic is prepared, which is recorded as D.

[0231] The properties of the polyurethane rigid foam prepared above are shown in Table 13 below:

[0232] Table 13

[0233]

[0234] It can be seen from Table 13 that the specific effects of the mixed methylamine carbonate solution and the mixed methylamine quaternary ammonium carbonate solution prepared by the present invention in preparing polyurethane rigid foam plastics are significantly better than those of existing foam materials.

Claims

1. A method for preparing mixed methylamine carbonate in situ by continuous fixed bed catalytic reaction, comprising the following steps: Using decomposed ammonia source compounds as raw materials, ammonia and carbon dioxide are obtained by thermal decomposition, methanol and ammonia are reacted by continuous fixed bed catalysis at high temperature to generate a methylamine mixture, and the methylamine mixture reacts with carbon dioxide and water to form a salt to obtain a mixed methylamine carbonate and / or methylamine bicarbonate; The decomposition ammonia source compound is an inorganic ammonium salt or an organic amine compound, the inorganic ammonium salt is selected from ammonium carbonate and ammonium bicarbonate, the organic amine is selected from ammonium carbamate and urea, and the urea is in the form of a urea aqueous solution; Thermal decomposition conditions are as follows: ammonium carbonate, ammonium carbamate or ammonium bicarbonate are thermally decomposed at 70-100°C and 0.35-0.55 MPa, urea aqueous solution is decomposed at 145-165°C and 0.35-0.70 MPa, and continuous fixed bed catalytic reaction conditions are 380-420°C and 1.25-1.50 MPa; The catalyst for the continuous fixed bed catalytic reaction is a mordenite catalyst, or ZSM-5, HY molecular sieve or SiO 2 -Al 2 O 3 Composition catalyst.

2. The method for preparing mixed methylamine carbonate in situ by continuous fixed bed catalytic reaction according to claim 1, It is characterized in that The mass concentration of the urea aqueous solution is from 40% to urea saturated aqueous solution.

3. The method for in-situ preparation of mixed methylamine carbonate by continuous fixed bed catalytic reaction according to claim 2, It is characterized in that The mass concentration of urea aqueous solution is 45%~50%.

4. The method for preparing mixed methylamine carbonate in situ by continuous fixed bed catalytic reaction according to claim 1, It is characterized in that The molar ratio of ammonia to methanol feed is 1:1-1:1.

5.

5. The method for preparing mixed methylamine carbonate in situ by continuous fixed bed catalytic reaction according to claim 1, It is characterized in that The temperature for the salt formation reaction of the methylamine mixture with carbon dioxide and water is 35~40℃ and the pressure is <0.35MPa.

6. The method for preparing mixed methylamine carbonate in situ by continuous fixed bed catalytic reaction according to claim 1, It is characterized in that The mixed methylamine bicarbonate solution further undergoes a ring-opening reaction with an epoxide to quaternize the mixed methylamine bicarbonate to prepare a mixed methylamine quaternary ammonium hydrogen carbonate; the temperature for the ring-opening reaction of the mixed methylamine carbonate quaternary ammonium salt solution with the epoxide is 35-60° C. and the pressure is less than 0.60 MPa.

7. The method for in-situ preparation of mixed methylamine carbonate by continuous fixed bed catalytic reaction according to claim 6, It is characterized in that When the epoxide is ethylene oxide, the reaction temperature and pressure are: 35~40℃ and <0.35MPa; When the epoxide is propylene oxide, the reaction temperature and pressure are 55-60°C and <0.60MPa.

8. Use of the mixed methylamine carbonate solution prepared according to claim 1 in the manufacture of polyurethane foam plastics.

9. Use of the mixed methylamine carbonate quaternary ammonium salt prepared according to claim 6 in the manufacture of polyurethane foam materials.

10. A device for preparing mixed methylamine carbonate in situ by continuous fixed-bed catalytic reaction, It is characterized in that The device comprises: a methanol storage tank and a decomposition device, wherein the methanol storage tank is connected to a gas phase mixer via a liquid phase metering pump and a vaporizer in sequence, the decomposition device is connected to the gas phase mixer via a mass flow meter, the gas phase mixer is connected to the top of a fixed bed reactor, the bottom of the fixed bed reactor is connected to a first gas-liquid separator via a back pressure valve, the bottom of the first gas-liquid separator is connected to the gas-liquid reactor via a first liquid compression pump, the top of the first gas-liquid separator is connected to a second gas-liquid separator, the top of the second gas-liquid separator is connected to the gas-liquid reactor via a gas compression pump, and the bottom of the second gas-liquid separator is connected to the gas phase mixer via a second liquid compression pump.

11. The device for in-situ preparation of mixed methylamine carbonate by continuous fixed-bed catalytic reaction according to claim 10, It is characterized in that There are two gas-liquid reactors, which are arranged in parallel.

12. The device for in-situ preparation of mixed methylamine carbonate by continuous fixed-bed catalytic reaction according to claim 10, It is characterized in that The temperature of the first gas-liquid separator was 10°C, and the temperature of the second gas-liquid separator was -35°C.

13. A method for preparing mixed methylamine carbonate in situ by continuous fixed bed catalytic reaction using the device of claim 10, 11 or 12, comprising the following steps: The methanol in the methanol storage tank is fed into the vaporizer through a liquid-phase metering pump to complete gasification, and then fed into a gas-phase mixer, mixed with the ammonia source gas-phase material decomposed by the decomposition device, and then fed into a fixed-bed reactor loaded with a catalyst for methylamination reaction; the methylamination reaction product is discharged through a back pressure valve, and enters a first gas-liquid separator to separate the mixed methylamine gas-phase product and water from the unconverted ammonia and carbon dioxide gas for gas-liquid separation, the liquid-phase mixed methylamine / water is fed into a first gas-liquid reactor and a second gas-liquid reactor into which metering water has been placed through a first liquid compression pump for salt-forming reaction, the unconverted ammonia and carbon dioxide gas are separated again in the second gas-liquid separator, the liquid ammonia is fed into the gas-phase raw material mixer through a second liquid compression pump as a return material, and the carbon dioxide gas is pumped into the first gas-liquid reactor and the second gas-liquid reactor through a gas compression pump for salt-forming reaction.

14. The method for in-situ preparation of mixed methylamine carbonate by continuous fixed bed catalytic reaction according to claim 13, It is characterized in that The temperature of the metered methanol entering the vaporizer is controlled at 80~120℃, thereby forming gaseous methanol at 0.30~0.40MPa; when urea aqueous solution is used as the decomposition ammonia source, the vaporization temperature of methanol is controlled at 110~120℃, forming gaseous methanol at 0.60~0.75MPa.

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