WO2019104810A1

WO2019104810A1 - Processing system and method for preparing acetal by using monohydric alcohol-air catalytic conversion

Info

Publication number: WO2019104810A1
Application number: PCT/CN2017/119180
Authority: WO
Inventors: 程金燮; 王科; 胡志彪; 凌华招; 黄宏; 徐晓峰; 温春辉; 李倩
Original assignee: 西南化工研究设计院有限公司
Priority date: 2017-11-29
Filing date: 2017-12-28
Publication date: 2019-06-06
Also published as: CN107867980A; CN107867980B

Abstract

Disclosed by the present invention are a processing system and method for preparing an acetal by using monohydric alcohol-air catalytic conversion, which solves the problems in the existing technology wherein costs are high, safety and environmental protection risks are high, conversion efficiency is low, fast and precise control of production conditions is not possible, and continuous industrial chemical production is not possible. The feeding system of the present invention comprises a raw material tank, a reciprocating metering pump, an air generating device, and a mass flow meter; a heating mixing system comprises a gas pre-heater, a liquid pre-heater, a gas pre-heating pipe, a liquid pre-heating pipe, a gas-liquid mixed pre-heating pipe, a vaporization mixer, and a overheating pipe; a catalytic conversion system comprises a fixed bed catalytic reactor; a condensing system comprises a deep cooler and a circulating refrigerator; a gas-liquid separation system comprises a gas-liquid separation tower, a product tank and a wet flow meter. A monohydric alcohol and air enter the heating mixing system by means of the feeding system and are heated and mixed, then entering the catalytic conversion system to react, a reaction tail gas being condensed by means of the condensing system and being separated by means of the gas-liquid separation system to obtain a liquid product containing the acetal.

Description

Process system and method for preparing acetal by monool-air catalytic conversion

Technical field

The invention belongs to the technical field of organic catalysis, and particularly relates to a process system and method for preparing acetal by monool-air catalytic conversion.

Background technique

Catalytic oxidation of monohydric alcohols produces acetals such as higher value added compounds. Methanol is an important basic chemical raw material. In the past 20 years, with the introduction of policies and layouts for the development of the coal chemical industry and the improvement of methanol production technology, a large number of large-scale methanol production facilities have been launched, and methanol production capacity has increased rapidly. As an important basic chemical raw material and product, due to insufficient development of its downstream products, methanol production has experienced serious overcapacity. At present, China's methanol production capacity can reach as high as 81 million tons, and the output can reach more than 42 million tons. Although the boom in dimethyl ether, acetic acid and methanol-to-olefins projects in recent years has stimulated methanol consumption to a certain extent, its overcapacity situation has not improved.

Dimethoxymethane (DMM) is commonly known as methylal, also known as dimethanol formal, methyl dimethyl ether, methylene dimethyl diether, molecular formula (CH ₃ O) ₂ CH ₂ , as a very Applied high value-added methanol downstream organic products, DMM is widely used in fuels and fuel additives, chemical intermediates, green solvents, spices, cosmetics, pharmaceuticals, rubber industry, paints, inks and other fields. Generally, in the presence of water, DMM is stable under alkaline and neutral conditions, does not hydrolyze between pH > 4.5-5, and is stable in nature. DMM does not produce peroxy compounds, does not need to add stabilizers, is most suitable for recycling, does not decompose when recycled; DMM atmospheric residence time is only 58h, its global warming potential is negligible; DMM molecular structure does not contain halogen atoms, its Ozone depletion potential is zero; DMM has very low toxicity, is very safe, does not accumulate in the environment, and is biodegradable. DMM is expected to play an important role in the field of energy and environmental protection. Under the current overcapacity of methanol production, the development of methylal acetal such as extensive applications and high value-added downstream chemicals and technologies is of great significance to the healthy development of coal chemical industry, especially the methanol industry.

The traditional process for producing DMM is the condensation of methanol and formaldehyde under the action of acidic catalysts (Shi Feng, Chen Yingzan, Luo Kai, et al. Preparation of high purity methylal) [J]. Fine Chemicals, 2012, 29(2): 178- 181), the process is long, the raw material consumption is large, the energy consumption is large, the formaldehyde-containing wastewater is large, the catalyst is seriously corroded to the equipment, and some of the products are not easily separated from the product. In addition, the two-stage process of dehydration of methanol to dimethyl ether and dimethyl ether oxidation to DMM (Wan Shuhan, Shang Yongchen. PW ₁₂ /SiO ₂ catalytic oxidation of dimethyl ether to obtain methylal] [J]. Process technology, 2016, (21): 118-119) There is a problem of low dimethyl ether conversion rate and DMM selectivity, and the synthesis route is long, the equipment investment is large, and the energy consumption is high. Sinopec Xu Chunmei and others replaced paraformaldehyde with methanol in methanol solvent and catalyzed the formation of DMM (CN101628860A) with H ₂ SO ₄ , although the catalytic distillation process increased the equilibrium conversion rate, and the change of raw materials reduced the wastewater. However, the cost has risen significantly, and the solvent and liquid acid are contaminated by the product. Zhang et al. reported a method for catalyzing the synthesis of DMM from methanol and CO ₂ at 150 ° C and 3.0 MPa by alkali-modified ionic liquid BmimOH (Zhang Q J, Zhao H Y, Lu B, et al. A novel strategy for conversion of methanol and CO ₂ into Dimethoxymethane in a basic ionic liquid [J]. Journal of Molecular Catalysis A: Chemical, 2016, 421: 117-121), although CO ₂ can be utilized, the reaction efficiency is low, the methanol conversion rate is only 2.4%, and industrialization is difficult. . Shan Yongkui et al. disclose a method for generating DMM by using dibromomethane, methanol or potassium hydroxide (CN101550068A). Although the conditions are mild and the utilization of dibromomethane is high, dibromomethane is toxic, pollutes the environment, and potassium hydroxide is difficult to dissolve. And neither the reaction efficiency nor the separation efficiency is disclosed. A new one-step catalyzed conversion of methanol to DMM using an oxidation-condensation coupling process (Secordel X, Yoboue A, Cristol S, et al. Supported oxorhenate catalysts prepared by thermal spreading of metal Re ⁰ for methanol conversion to methylal [J].Journal of Solid State Chemistry, 2011, 184: 2806-2811) not only has high production efficiency, but also eliminates the methanol-formaldehyde section, shortens the process, reduces investment, solves the problem of wastewater and equipment corrosion, and does not exist in the separation of catalyst and product. Polluted and other issues.

Due to the exothermic heat of the reaction process, considering the heat transfer of the catalyst bed and the explosion limit of combustibles, O ₂ must be mixed with a certain concentration of dilution gas. The prior art generally uses a reservoir with a dilution gas (N ₂ , He or Ar). Tanks, there is a safety risk, or a separate dilution of the gas to solve the problem, but in the industry not only need to increase gas, buffer tank, power transmission, flow control, pipeline and other links, and more dilution gas Production cost item; the literature reports that the raw material methanol is generally contained in the glass evaporation bottle, and the methanol in the glass bottle is brought into the conversion system by the flow of gas (any combination of O ₂ and diluent gas), which cannot be quickly and accurately adjusted. The amount of methanol will also be caused by fluctuations in the amount of methanol and temperature due to changes in gas flow, temperature and methanol balance, affecting the conversion reaction and the staff's true understanding of the conversion; product liquid components (water, methanol, deflation) Aldehydes, methyl formate, dimethyl ether, formaldehyde) are almost all low-boiling components. It is difficult to cool all the components in the prior art by primary cooling, which not only causes product loss, but also shadows. Calculation analysis and accurate judgment of the staff on the conversion situation, while the cooling method of the refrigerator without heat recovery also caused the system heat loss; the glass equipment (glass evaporator, reaction tube, cold trap, etc.) adopted by the above scheme limits the reaction Under normal pressure, the relationship between pressure and reaction cannot be investigated experimentally, which reduces the understanding of the technology and is not conducive to the design, material selection and production operations of industrialization schemes.

Therefore, the present invention provides a process system and method for the catalytic conversion of monohydric alcohol-air to produce acetal, which can improve production efficiency, reduce equipment investment, production cost and safety and environmental protection risks, and at the same time facilitate rapid and precise control of production conditions and continuous industrial production. It has become an urgent problem to be solved by those skilled in the art.

Summary of the invention

The invention provides a process system for monohydric alcohol-air catalytic conversion to obtain acetal, which solves the problem of large investment in equipment, high production cost and high energy consumption when the monohydric alcohol-air catalytic conversion acetal is prepared in the prior art. The conversion efficiency is low, the safety and environmental protection risks are large, the production conditions cannot be quickly and accurately controlled, and the problem of continuous industrial production cannot be continuously achieved.

The invention also provides a method for the preparation of acetal by monool-air catalytic conversion.

The technical solution adopted by the present invention is as follows:

The invention relates to a process system for preparing a acetal by a monool-air catalytic conversion, comprising a feed system, a heating mixing system, a catalytic conversion system, a condensation system and a gas-liquid separation system;

The feeding system comprises a raw material tank containing a monohydric alcohol liquid, a reciprocating metering pump connected to the outlet pipe of the raw material tank, an air generating device for generating air, and a mass flow meter connected to the outlet pipe of the air generating device;

The heating mixing system includes a gas preheater, a liquid preheater, a gas preheating pipe, a liquid preheating pipe, a gas-liquid mixed preheating pipe, a vaporization mixer and a superheating pipe, and the gas preheater and the liquid preheater are all disks. In the tubular heat exchanger, the shell inlet of the gas preheater is connected to the outlet pipe of the mass flow meter, and the gas preheater is used for preheating the air sent from the air generating device, and the shell inlet of the liquid preheater is The outlet pipe of the reciprocating metering pump is connected, and the liquid preheater is used for preheating the monohydric alcohol liquid conveyed from the raw material tank, and the shell-side outlet of the gas preheater is connected with the inlet of the gas preheating pipe, and the liquid preheater is connected The shell-side outlet is connected to the inlet of the liquid preheating pipe, the outlet of the gas preheating pipe, and the outlet of the liquid preheating pipe are respectively connected with the inlet of the gas-liquid mixed preheating pipe, and the inlet of the vaporization mixer and the gas-liquid mixed preheating pipe are connected. The outlet connection, the outlet of the vaporization mixer is connected to the inlet of the superheating pipe;

The catalytic conversion system comprises a fixed bed reactor packed with an oxidation catalyst, and the reactor is connected to an outlet of the superheating pipe for catalytically reacting the mixed gas sent from the vaporization mixer;

The condensing system comprises a deep cooler and a circulating refrigerator, the tube inlet of the gas preheater is connected with the outlet pipe of the reactor, and the pipe outlet of the gas preheater is connected with the pipe inlet pipe of the liquid preheater, the cryocooler For the coiled heat exchanger, the tube inlet of the cryocooler is connected to the tube outlet outlet of the liquid preheater, and the circulating refrigerator is connected to the shell side pipeline of the cryostat, and the reaction tail gas generated from the reactor is in the gas preheating The heat exchanger is subjected to primary heat exchange with the air delivered from the air generating device to the gas preheater shell, and then enters the tube of the liquid preheater and is transported from the raw material tank to the liquid preheater shell. The monohydric alcohol liquid in the process performs secondary heat exchange, and finally carries out three-stage heat exchange with the freezing liquid conveyed from the circulating refrigerator to the shell of the cryocooler in the tube of the deep cooler to obtain the liquid component in the reaction tail gas. a fully condensed gas-liquid mixture;

The gas-liquid separation system comprises a gas-liquid separation tower, a product tank and a wet flow meter, and the gas-liquid separation tower is connected with an outlet pipe of a deep-cooler tube, and the gas-liquid separation tower is provided with a gas outlet and a liquid outlet, a product tank and a liquid outlet. The pipeline is connected, the wet flowmeter is connected with the outlet pipe, and the gas-liquid mixture condensed by the cryocooler is separated into the gas-liquid separation tower, and the separated liquid enters the product tank, and the separated gas is separately processed by the wet flowmeter.

Further, a metering device is provided at the bottom of the raw material tank for checking the flow rate of the monohydric alcohol liquid to precisely assist in controlling the feed.

Further, the first flow valve is disposed on the pipeline connecting the mass flow meter and the gas preheater, and the first ball valve is disposed on the first venting pipe, and the pipe connected to the liquid heat exchanger is arranged with zero row. a pipe, and a second ball valve is arranged on the zero pipe, a second venting pipe is arranged on the pipe connecting the superheat pipe and the reactor, and a third ball valve is arranged on the second venting pipe.

Further, a fourth ball valve is disposed on the pipeline connected to the gas-liquid separation tower, the product tank is connected with a product collection pipeline, and the product collection pipeline is provided with a fifth ball valve and a needle valve, and the product tank is discharged. The air port is connected with the air outlet pipe of the air generating device, and the sixth ball valve is arranged on the pipe, and the back pressure valve is arranged on the pipe connected with the gas liquid separation tower and the wet flow meter, and the air outlet of the gas-liquid separation tower and the air generating device The outlet pipe is connected and the seventh ball valve and pressure gauge are provided on the pipe. By venting the product tank 26 after sampling to balance the pressure difference between the sampled product tank 26 and the system, system fluctuations are avoided.

Further, a first thermocouple is arranged on the superheating pipe, a second thermocouple is arranged on the upper end of the constant temperature section of the reactor, a third thermocouple is arranged in the center of the constant temperature section, and a fourth thermocouple is arranged on the lower end of the constant temperature section, and the reactor is heated. A fifth thermocouple is arranged in the upper part of the furnace, a sixth thermocouple is arranged in the middle of the heating furnace, and a seventh thermocouple is arranged in the lower part of the heating furnace.

The method for preparing an acetal by a monool-air catalytic conversion according to the present invention comprises the apparatus for preparing an acetal by a monool-air catalytic conversion as described above, which comprises the following steps:

Step A: feeding: the air generated by the air generating device is controlled by the mass flow meter to enter the gas preheater; the monohydric alcohol in the raw material tank is controlled by the reciprocating metering pump to enter the liquid preheater;

Step B: heating and mixing: the air heated by the gas preheater is further heated by the gas preheating pipe to enter the gas-liquid mixing preheating pipe, and the monohydric alcohol heated by the liquid preheater is further heated by the liquid preheating pipe to enter the gas and liquid. The preheating pipeline is mixed, and the monohydric alcohol and air in the gas-liquid mixing preheating pipeline are reheated and initially mixed, and then enter the vaporization mixer, and the reheated monohydric alcohol is completely vaporized in the vaporization mixer and thoroughly mixed with the reheated air. To obtain a mixed gas;

Step C: catalytic conversion: after the mixed gas is heated to a catalytic reaction temperature through a heat pipe, the reaction is carried out into a reactor packed with an oxidation catalyst;

Step D: Cooling condensate liquefaction: The reaction tail gas generated by the reactor is subjected to primary heat exchange in the tube of the gas preheater and air sent from the air generating device to the shell of the gas preheater, and then into the liquid preheating. The secondary heat transfer between the tube and the monohydric alcohol liquid from the raw material tank to the liquid preheater shell is carried out, and finally reaches the tube of the cryocooler and is transported from the circulating refrigerator to the cryocooler shell. The internal chilled liquid is subjected to tertiary heat exchange to obtain a gas-liquid mixture in which the liquid component in the reaction tail gas is completely condensed;

Step E: Gas-liquid separation: The gas-liquid mixture condensed by the cryocooler is separated into the gas-liquid separation tower, and the separated liquid enters the product tank, and the separated gas is separately processed by the wet flow meter.

Further, the acetal is a product of a monoaldehyde condensation of a monohydric alcohol and a monohydric alcohol, and the oxidation catalyst is selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Ce, Zr, Nb, Mo, Ru, Sn Any one or more of Sb, Ta, W, Os, Ir, Pt, Au catalyst or heteropolyacid catalyst.

Further, the oxidation catalyst is selected from any one or more of V, Mo, Fe or heteropolyacid catalysts, the outlet pressure of the air generating device is 0.0 MPa to 10.5 MPa, and the liquid space velocity of the monohydric alcohol is 0.1 h ^-1 -3.0h ^-1 , the ratio of the amount of monohydric alcohol to air is 1:50-2:1, the outlet pressure of the reciprocating metering pump is 0.0MPa-10.3MPa, gas preheating pipeline, liquid preheating pipeline, gas The temperature of the liquid mixing preheating pipe is 20 ° C - 100 ° C, the temperature of the vaporizing mixer is 30 ° C - 400 ° C, the temperature of the superheating pipe is 80 ° C - 600 ° C, and the temperature in the reactor is 80 ° C - 600 ° C, back pressure valve control system pressure 0.0MPa-10.0MPa, temperature cycling freezer is -40 ℃ to 10 ℃, the circulation amount of cryogenic liquid is 0.6m ^³ /h-4.8m ³ / h.

Further, the liquid air velocity of the monohydric alcohol is 0.3h ^-1 -2.5h ^-1 , the ratio of the amount of the monohydric alcohol to the air is 1:15-8:5, and the temperature in the reactor is 80 ° C -300 ° C backpressure control valve system pressure 0.0MPa-3.0MPa, using a temperature cycle of -40 ℃ refrigerator to -25 deg.] C, the circulation amount of cryogenic liquid is 1.2m ^³ /h-4.0m ³ / h.

Further, the liquid separated in the step E includes water, the monohydric alcohol and the corresponding aldehyde, acid, monocarboxylic acid ester, dialkyl ether and acetal of the monohydric alcohol; The gas includes N ₂ , O ₂ , CO, and CO ₂ .

Compared with the prior art, the beneficial effects of the present invention are:

The invention has the advantages of simple structure, scientific design and simple operation, can effectively reduce equipment investment, production cost and energy consumption, is safe and environmentally friendly, and has high conversion efficiency, and is convenient for quickly and accurately controlling production conditions, and can continuously industrialize production.

The invention adopts the cheap and easily available air as the mixture of the oxidizing gas and the diluent gas, and only needs to provide one air generating device-mass flow meter, which not only ensures the same reaction efficiency, but also reduces the equipment investment and gas cost, and eliminates The safety hazard brought by the storage tank.

The invention utilizes the reciprocating metering pump feeding system and the metering device, not only realizes the rapid and precise adjustment of the liquid intake, the feed maintains stability, ensures the conversion efficiency, and is convenient for the worker to check the raw material intake, analyze and calculate, and accurately Determine the conversion.

The invention adopts a three-stage condensation mode of reaction tail gas-air→reaction tail gas-monohydric alcohol→reaction tail gas-refrigerant liquid, not only fully condenses the liquid phase component in the reaction product, but also improves the liquid product yield, and recycles The heat carried by the product realizes the preheating of the raw material gas and the monohydric alcohol, thereby reducing the condensation energy consumption.

The air generating device and the reciprocating metering pump used in the invention have self-boosting function, and other pipes, valves and equipments (except for the wet flowmeter after pressure relief) use pressure-resistant materials, and the staff can study the pressure and raw material conversion rate. The intrinsic connection of product selectivity and deeper understanding of this change process, in addition to the use of air properties and the design of continuous material flow technology make this technology particularly suitable for continuous industrial production projects.

DRAWINGS

Figure 1 is a schematic view of the structure of the present invention.

Wherein, the corresponding name of the reference numeral is:

1-air generator, 2-mass flow meter, 3-first ball valve, 4-air preheater, 5-material tank, 6-metering device, 7-reciprocating metering pump, 8-second ball valve, 9- Liquid preheater, 10-gas preheating pipe, 11-vaporizing mixer, 12-superheated pipe, 13-first thermocouple, 14-third ball valve, 15-reactor, 16-second thermocouple, 17- Third thermocouple, 18-fourth thermocouple, 19-fifth thermocouple, 20-sixth thermocouple, 21-seventh thermocouple, 22-cryogenic cooler, 23-cycle freezer, 24-gas-liquid separation Tower, 25-fourth ball valve, 26-product tank, 27- seventh ball valve, 28-back pressure valve, 29-wet flow meter, 30-six ball valve, 31-pressure gauge, 32-fifth ball valve, 33- Needle valve, 34-liquid preheating pipe, 35-gas-liquid mixed preheating pipe.

Detailed ways

The present invention will be further described with reference to the accompanying drawings and embodiments, which, however, are not limited to the following embodiments.

Example 1

As shown in FIG. 1 , the present embodiment provides a process system for mono-alcohol-air catalytic conversion to produce acetal, which has simple structure, scientific design, simple operation, and can effectively reduce equipment investment, production cost and energy consumption, and safety. Environmentally friendly, efficient conversion, and convenient and precise control of production conditions, enabling continuous industrial production. The monohydric alcohol-air catalytic conversion process system for preparing acetal comprises a feed system, a heating mixing system, a catalytic conversion system, a condensing system, and a gas-liquid separation system.

The feed system includes a raw material tank 5 containing a monohydric alcohol liquid, a reciprocating metering pump 7 connected to an outlet pipe of the raw material tank 5, an air generating device 1 for generating air, and the air generating device 1 Mass flow meter connected to the outlet pipe 2.

The heating and mixing system includes a gas preheater 4, a liquid preheater 9, a gas preheating pipe 10, a liquid preheating pipe 34, a gas-liquid mixing preheating pipe 35, a vaporizing mixer 11 and a superheating pipe 12, the gas The preheater 4 and the liquid preheater 9 are both coil heat exchangers, and a shell inlet of the gas preheater 4 is connected to an outlet pipe of the mass flow meter 2, the gas preheater 4 for preheating air delivered from the air generating device 1, the shell inlet of the liquid preheater 9 being connected to an outlet pipe of the reciprocating metering pump 7, the liquid preheater 9 For preheating the monohydric alcohol liquid conveyed from the raw material tank 5, the shell-side outlet of the gas preheater 4 is connected to the inlet of the gas preheating pipe 10, and the shell side of the liquid preheater 9 The outlet is connected to the inlet of the liquid preheating pipe 34, and the outlet of the gas preheating pipe 10 and the outlet of the liquid preheating pipe 34 are respectively connected to the inlet of the gas-liquid mixing preheating pipe 35, and the inlet of the vaporizing mixer 11 is attached. Connected to the outlet of the gas-liquid mixing preheating pipe 35, the vaporization Together the outlet 11 is connected to the inlet conduit 12 of overheating.

The catalytic conversion system includes a fixed bed reactor 15 packed with an oxidation catalyst, and the reactor 15 is connected to an outlet of the superheating pipe 12 for catalytically reacting a mixed gas sent from the vaporization mixer 11;

The condensing system includes a cryocooler 22 and a circulation chiller 23, the tube inlet of the gas preheater 4 is connected to an outlet conduit of the reactor 15, and the tube outlet of the gas preheater 4 is The tube inlet inlet pipe of the liquid preheater 9 is connected, the cryocooler 22 is a coil heat exchanger, the pipe inlet of the cryocooler 22 and the pipe outlet pipe of the liquid preheater 9 Connected, the recirculating refrigerator 23 is connected to the shell side pipe of the cryocooler 22, and the reaction off-gas generated from the reactor 15 is transported from the air generating device 1 in the pipe path of the gas preheater 4 After the air in the shell side of the gas preheater 4 undergoes primary heat exchange, it enters the tube path of the liquid preheater 9 and is transported from the raw material tank 5 to the liquid preheater 9 shell. The monohydric alcohol liquid in the process is subjected to secondary heat exchange, and finally to the cylinder of the cryocooler 22 and the refrigerating liquid sent from the circulating refrigerator 23 to the shell side of the cryocooler 22 for three-stage exchange. Heat, a gas-liquid mixture in which the liquid component of the reaction tail gas is completely condensed is obtained.

The gas-liquid separation system includes a gas-liquid separation column 24, a product tank 26, and a wet flow meter 29, and the gas-liquid separation tower 24 is connected to an outlet pipe of the deep-cooler 22 tube, the gas-liquid separation tower 24 An air outlet and a liquid outlet are provided, the product tank 26 is connected to the liquid outlet pipe, the wet flow meter 29 is connected to the gas outlet pipe, and the gas-liquid mixture condensed by the cryocooler 22 enters The gas-liquid separation column 24 is separated, and the separated liquid enters the product tank 26, and the separated gas is separately processed by the wet flow meter 29.

In order to further control the precise feed of the monohydric alcohol, the monohydric-air catalytic conversion process for preparing the acetal further comprises providing a bottom of the raw material tank 5 for checking the flow rate of the monohydric alcohol liquid to precisely control the feed. Metering device 6.

In order to ensure safe and stable operation of the monohydric alcohol-air catalytic conversion acetal system, the mass flow meter 2 is connected to the gas preheater 4 with a first venting pipe, and the first venting pipe A first ball valve 3 is provided, a pipe connecting the reciprocating metering pump 7 to the liquid heat exchanger 9 is provided with a zero-discharging pipe, and a second ball valve 8 is disposed on the row-zero pipe, and the superheating pipe 12 is provided. A second venting pipe is disposed on the pipe connected to the reactor 15, and a third ball valve 14 is disposed on the second venting pipe.

In order to facilitate the efficient operation and control of the monohydric alcohol-air catalytic conversion acetal system, a fourth ball valve 25 is disposed on the pipeline connecting the cryocooler 22 and the gas-liquid separation tower 24, and the product tank 26 The outlet of the product is connected with a product collecting pipe, and the product collecting pipe is provided with a fifth ball valve 32 and a needle valve 33, and an air outlet of the product tank 26 is connected to an air outlet pipe of the air generating device 1 and the pipe is provided There is a sixth ball valve 30, and a pipe connecting the gas-liquid separation tower 24 and the wet flow meter 29 is provided with a back pressure valve 28, and an air outlet of the gas-liquid separation tower 24 and the air generating device 1 The port pipe is connected and the seventh ball valve 27 and the pressure gauge 31 are provided on the pipe. By venting the product tank 26 after sampling to balance the pressure difference between the sampled product tank 26 and the system, system fluctuations are avoided.

In order to ensure the reaction temperature in the reactor 15, a first thermocouple 13 is disposed on the superheating pipe 12, a second thermocouple 16 is disposed on the upper end of the constant temperature section of the reactor 15, and a third portion is provided in the center of the constant temperature section. a thermocouple 17 and a lower end of the thermostatic section are provided with a fourth thermocouple 18, a fifth thermocouple 19 is disposed on the upper portion of the heating furnace outside the reactor 15, a sixth thermocouple 20 is disposed in the middle of the heating furnace, and a lower portion of the heating furnace is disposed. Seventh thermocouple 21.

In order to precisely control the reaction temperature, the first thermocouple 13, the second thermocouple 16, the third thermocouple 17, the fourth thermocouple 18, the fifth thermocouple 19, the sixth thermocouple 20, and the seventh thermocouple 21 is connected to an external temperature control system.

Example 2

The present embodiment provides a method for preparing a acetal by the monool-air catalytic conversion of the present invention, which is carried out by using the apparatus of the embodiment 1, and specifically comprises the following steps:

The pure methanol is used as the raw material of the monohydric alcohol, and the air is used as the mixed gas of the oxidizing gas and the diluent gas, and the methanol feed amount of the reciprocating metering pump 7 is set to 5.0 mL/h, and the outlet pressure of the air generating device 1 is 0.53 MPa, and the mass is The air flow rate of the flow meter 2 is 1.96 L/h;

The methanol from the reciprocating metering pump 7 enters the liquid preheater 9, and the exhaust gas after the reaction with the reactor 15 is preheated, and then further heated into the gas-liquid mixing preheating pipe 35 through the liquid preheating pipe 34. After the air from the mass flow meter 2 is heated by the gas preheater 4, it is further heated into the gas-liquid mixing preheating pipe 35 via the gas preheating pipe 10, and the monohydric alcohol and the gas-liquid mixed preheating pipe 35 are The air is heated again and initially mixed and then enters the vaporization mixer 11.

The temperature of the gas preheating pipe 10, the liquid preheating pipe 34, and the gas-liquid mixed preheating pipe 35 are both 70 ° C, and the temperature of the vaporizing mixer 11 is 90 ° C. The methanol is completely vaporized by heating in the vaporization mixer 11 and thoroughly mixed with air to obtain a mixed gas.

The mixed gas was superheated to 120 ° C through the hot pipe 12, and the reaction was carried out in a reactor 15 packed with 10 mL of a vanadium catalyst at a reaction temperature of 120 °C.

The reaction tail gas generated by the reactor 15 is subjected to primary heat exchange with the air sent from the air generating device 1 to the shell side of the gas preheater 4 in the pipe path of the gas preheater 4, and then enters the liquid preheater 9 The secondary alcohol heat transfer is carried out in the tube and from the raw material tank 5 to the monohydric alcohol liquid in the shell side of the liquid preheater 9, and finally reaches the tube of the deep cooler 22 and is transported from the circulating refrigerator 23 to the deep cooler. The cold liquid in the shell side is subjected to tertiary heat exchange to completely condense the liquid component in the reaction tail gas to form a gas-liquid mixture. Among them, the temperature of the freezing liquid was set to -15 ° C to -5 ° C, and the circulation amount of the freezing liquid was 1.2 m ³ /h.

The gas-liquid mixture condensed by the cryocooler 22 is separated into the gas-liquid separation column 24, and the separated liquid enters the product tank 26, and the separated gas is separately treated by the back pressure valve 28 and the wet flow meter 29. The separated liquid components were water, methanol, methylal, methyl formate, dimethyl ether, formaldehyde and formic acid, and the pressure of the back pressure valve control system was 0.5 MPa.

After the system was stabilized for 15 h, the gas phase and the liquid phase were separately analyzed in an Agilent 6820 chromatograph. The relative deviation of the monohydric alcohol intake from the pump set value, the conversion of monohydric alcohol, the selectivity of the acetal, and the separation of the gas-liquid separation column were calculated. The composition of the gas is as follows:

The gas composition separated by the gas-liquid separation tower is calculated by the chromatographic workstation according to the corrected area normalization method;

The results are shown in Table 1 below.

Table 1 Comparison of Process Indicators of Example 2-5

Example 3

The pure ethanol is used as the raw material of the monohydric alcohol, and the air is used as the mixed gas of the oxidizing gas and the diluent gas. The ethanol feed amount of the reciprocating metering pump 7 is set to 7.5 mL/h, and the outlet pressure of the air generating device 1 is 3.0 MPa. The air flow rate of the flow meter 2 is 8.30 L/h;

The ethanol from the reciprocating metering pump 7 enters the liquid preheater 9, and the exhaust gas after the reaction with the reactor 15 is preheated, and then further heated into the gas-liquid mixing preheating pipe 35 through the liquid preheating pipe 34. After the air from the mass flow meter 2 is heated by the gas preheater 4, it is further heated into the gas-liquid mixing preheating pipe 35 via the gas preheating pipe 10, and the monohydric alcohol and the gas-liquid mixed preheating pipe 35 are The air is heated again and initially mixed and then enters the vaporization mixer 11.

The temperature of the gas preheating pipe 10, the liquid preheating pipe 34, and the gas-liquid mixing preheating pipe 35 are both 100 ° C, and the temperature of the vaporizing mixer 11 is 220 ° C. The ethanol is completely vaporized by heating in the vaporization mixer 11 and thoroughly mixed with air to obtain a mixed gas.

The mixed gas was superheated to 260 ° C through the hot pipe 12, and the reaction was carried out in a reactor 15 packed with 5 mL of a molybdenum catalyst at a reaction temperature of 260 °C.

The reaction tail gas generated by the reactor 15 is subjected to primary heat exchange with the air sent from the air generating device 1 to the shell side of the gas preheater 4 in the pipe path of the gas preheater 4, and then enters the liquid preheater 9 The secondary alcohol heat transfer is carried out in the tube and from the raw material tank 5 to the monohydric alcohol liquid in the shell side of the liquid preheater 9, and finally reaches the tube of the deep cooler 22 and is transported from the circulating refrigerator 23 to the deep cooler. The cold liquid in the shell side is subjected to tertiary heat exchange to completely condense the liquid component in the reaction tail gas to form a gas-liquid mixture. Among them, the temperature of the freezing liquid was set to -5 ° C to 5 ° C, and the circulation amount of the freezing liquid was 4.5 m ³ /h.

The gas-liquid mixture condensed by the cryocooler 22 is separated into the gas-liquid separation column 24, and the separated liquid enters the product tank 26, and the separated gas is separately treated by the back pressure valve 28 and the wet flow meter 29. The separated liquid components were water, ethanol, acetal, ethyl acetate, diethyl ether, acetaldehyde and acetic acid, and the pressure of the back pressure valve control system was 2.6 MPa.

After the system was stabilized for 15 h, the gas phase and the liquid phase were separately analyzed in an Agilent 6820 chromatograph. The relative deviation of the monohydric alcohol intake from the pump set value, the conversion of monohydric alcohol, the selectivity of the acetal, and the separation of the gas-liquid separation column were calculated. The composition of the gas is the same as that of the embodiment 2. The specific results are shown in Table 1.

Example 4

The pure methanol is used as the raw material of the monohydric alcohol, and the air is used as the mixed gas of the oxidizing gas and the diluent gas, and the methanol feed amount of the reciprocating metering pump 7 is set to 33.0 mL/h, and the outlet pressure of the air generating device 1 is 0.3 MPa, and the mass is The air flow rate of the flow meter 2 is 18.26 L/h;

The temperature of the gas preheating pipe 10, the liquid preheating pipe 34, and the gas-liquid mixing preheating pipe 35 are both 50 ° C, and the temperature of the vaporizing mixer 11 is 160 ° C. The ethanol is completely vaporized by heating in the vaporization mixer 11 and thoroughly mixed with air to obtain a mixed gas.

The mixed gas was superheated to 200 ° C through the hot pipe 12, and the reaction was carried out in a reactor 15 packed with 15 mL of a heteropolyacid catalyst at a reaction temperature of 200 °C.

The reaction tail gas generated by the reactor 15 is subjected to primary heat exchange with the air sent from the air generating device 1 to the shell side of the gas preheater 4 in the pipe path of the gas preheater 4, and then enters the liquid preheater 9 The secondary alcohol heat transfer is carried out in the tube and from the raw material tank 5 to the monohydric alcohol liquid in the shell side of the liquid preheater 9, and finally reaches the tube of the deep cooler 22 and is transported from the circulating refrigerator 23 to the deep cooler. The cold liquid in the shell side is subjected to tertiary heat exchange to completely condense the liquid component in the reaction tail gas to form a gas-liquid mixture. Among them, the temperature of the freezing liquid was set to -30 ° C to -10 ° C, and the circulation amount of the freezing liquid was 2.9 m ³ /h.

The gas-liquid mixture condensed by the cryocooler 22 is separated into the gas-liquid separation column 24, and the separated liquid enters the product tank 26, and the separated gas is separately treated by the back pressure valve 28 and the wet flow meter 29. The separated liquid components were water, methanol, methylal, methyl formate, dimethyl ether, formaldehyde and formic acid, and the pressure of the back pressure valve control system was 0.1 MPa.

Example 5

This embodiment is a comparative example. Specifically, in comparison with Embodiment 2, this embodiment replaces the cryocooler with a cold trap, replaces the heating and mixing system of Embodiment 2 with a glass vaporizer, and does not provide the superheating pipe 12. At the same time, due to the limitation of the glass system, the reaction pressure is normal pressure. All other conditions are the same.

The air enters the glass vaporizer containing methanol through a pipe, carries methanol into the reactor 15 for reaction, and changes the feed amount of methanol by adjusting the temperature inside the glass vaporizer. The reaction tail gas generated by the reactor 15 is cooled by the secondary heat exchange of the raw material air and the methanol, directly enters the cold trap to condense, and controls the freezing temperature term.

In comparison with the above examples, the data is shown in Table 1.

Compared with the second embodiment, the methanol feed amount can be conveniently and accurately set. It is very time-consuming, troublesome, and the accuracy is poor to adjust the methanol feed amount to the target value in the embodiment 5, and the relative deviation is up to 14.87%. Example 2 is 16.5 times. In the gas composition separated in the gas-liquid separation column in Example 2, there is no liquid phase component, and the gas separated in the gas-liquid separation column in Example 5 contains a constant methyl acetal, methyl formate and dimethyl ether, which is The reaction product did not give a direct indication of better condensation. In addition, the methanol conversion rate of Example 5 was 9.0% lower than that of Example 2, the selectivity of methylal was 12.8% lower, and the production efficiency was lower than that of Example 2, which may be because the raw materials were not preheated, overheated, thoroughly mixed, and the like. The temperature and the mixing degree of the raw material into the catalyst bed are reduced, the collision probability between the raw material molecules is reduced, and the conversion reaction is weakened. It can also be seen from the data sheet that the monool conversion rate and acetal selectivity of the method are improved as compared with the prior art.

It can be seen that the invention not only saves equipment investment, reduces gas cost, is safe and environmentally friendly, but also facilitates rapid and precise control, accurate analysis and judgment, widening operating conditions, reducing condensation energy consumption, high conversion efficiency, and is particularly suitable for continuous industrial production. .

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

A process system for monohydric alcohol-air catalytic conversion to produce acetal, which comprises a feed system, a heating mixing system, a catalytic conversion system, a condensation system and a gas-liquid separation system;

The feeding system comprises a raw material tank (5) containing a monohydric alcohol liquid, a reciprocating metering pump (7) connected to an outlet pipe of the raw material tank (5), and an air generating device for generating air (1) And a mass flow meter (2) connected to the outlet pipe of the air generating device (1);

The heating and mixing system comprises a gas preheater (4), a liquid preheater (9), a gas preheating pipe (10), a liquid preheating pipe (34), a gas-liquid mixed preheating pipe (35), and a vaporization mixing. (11) and a superheating pipe (12), the gas preheater (4) and the liquid preheater (9) are both coil heat exchangers, and the shell of the gas preheater (4) a process inlet is connected to an outlet conduit of the mass flow meter (2) for preheating air delivered from the air generating device (1), the liquid preheating The shell inlet of the vessel (9) is connected to the outlet conduit of the reciprocating metering pump (7) for the monohydric alcohol liquid to be conveyed from the raw material tank (5) Preheating, the shell-side outlet of the gas preheater (4) is connected to the inlet of the gas preheating pipe (10), the shell-side outlet of the liquid preheater (9) and the liquid preheating pipe (34) An inlet connection, an outlet of the gas preheating pipe (10), and an outlet of the liquid preheating pipe (34) are respectively connected to an inlet of the gas-liquid mixing preheating pipe (35), and an inlet of the vaporization mixer (11) With the gas and liquid Together preheating duct outlet (35) is connected to the mixer inlet outlet of the vaporizing (11) and the superheater pipes (12) is connected;

The catalytic conversion system comprises a fixed bed reactor (15) packed with an oxidation catalyst, the reactor (15) being connected to an outlet of a superheating conduit (12) for transporting from the vaporization mixer (11) a mixed gas for catalytic reaction;

The condensing system comprises a cryocooler (22) and a circulating chiller (23), the tube inlet of the gas preheater (4) being connected to an outlet conduit of the reactor (15), the gas preheating The tube outlet of the device (4) is connected to a tube inlet inlet pipe of the liquid preheater (9), the cryocooler (22) is a coil heat exchanger, and the cryocooler (22) a tube inlet is connected to the tube outlet conduit of the liquid preheater (9), the circulation refrigerator (23) is connected to the shell side conduit of the cryocooler (22), and is produced from the reactor (15) The reaction off-gas is subjected to primary heat exchange in the tube of the gas preheater (4) and air sent from the air generating device (1) to the shell of the gas preheater (4). Re-entering the tube of the liquid preheater (9) and the monohydric alcohol liquid transported from the raw material tank (5) to the shell of the liquid preheater (9) for secondary heat exchange, and finally to The third stage heat exchange is performed in the tube of the cryocooler (22) and the freezing liquid sent from the circulating refrigerator (23) to the shell of the cryocooler (22) to obtain the reaction tail gas. a gas-liquid mixture in which the liquid component is completely condensed;

The gas-liquid separation system comprises a gas-liquid separation tower (24), a product tank (26) and a wet flow meter (29), and the gas-liquid separation tower (24) and the outlet of the cryocooler (22) a pipe connection, the gas-liquid separation tower (24) is provided with a gas outlet and a liquid outlet, the product tank (26) is connected to the outlet pipe, the wet flow meter (29) and the gas outlet pipe Connected, the gas-liquid mixture condensed by the cryocooler (22) enters the gas-liquid separation tower (24) for separation, and the separated liquid enters the product tank (26), and the separated gas passes through the wet flowmeter. (29) Afterwards, it will be processed separately.
The process system for preparing an acetal by a monool-air catalytic conversion according to claim 1, further comprising a bottom portion of the raw material tank (5) for checking a flow rate of the monohydric alcohol liquid feed. A metering device (6) that precisely controls the feed.
The process system for preparing an acetal by a monool-air catalytic conversion according to claim 1, wherein the mass flow meter (2) is connected to the gas preheater (4) There is a first venting pipe, a first ball valve (3) is disposed on the first venting pipe, and a pipe connecting the reciprocating metering pump (7) and the liquid heat exchanger (9) is provided with a zero pipe And the second ball valve (8) is disposed on the zero-line pipe, the pipe connected to the reactor (15) is provided with a second venting pipe, and the second venting pipe is provided There is a third ball valve (14).
A process system for preparing an acetal by a monool-air catalytic conversion according to claim 1, wherein the cryocooler (22) is disposed on a pipe connected to the gas-liquid separation column (24). There is a fourth ball valve (25), an outlet of the product tank (26) is connected with a product collecting pipe, and a fifth ball valve (32) and a needle valve (33) are provided on the product collecting pipe, and the product tank (26) The gas outlet is connected to the gas outlet pipe of the air generating device (1) and the pipe is provided with a sixth ball valve (30), and the gas-liquid separation tower (24) is connected to the wet flow meter (29) a pipeline is provided with a back pressure valve (28), an air outlet of the gas-liquid separation tower (24) is connected to an air outlet pipe of the air generating device (1), and a seventh ball valve (27) is arranged on the pipe. And pressure gauge (31).
The process system for preparing acetal by monool-air catalytic conversion according to claim 1, wherein the superheating pipe (12) is provided with a first thermocouple (13), and the reactor ( 15) a second thermocouple (16) is disposed at an upper end of the constant temperature section, a third thermocouple (17) is disposed at a center of the constant temperature section, and a fourth thermocouple (18) is disposed at a lower end of the constant temperature section, wherein the reactor (15) A fifth thermocouple (19) is arranged in the upper part of the heating furnace, a sixth thermocouple (20) is arranged in the middle of the heating furnace, and a seventh thermocouple (21) is arranged in the lower part of the heating furnace.
A method for preparing an acetal by a monohydric alcohol-air catalytic conversion, characterized in that the apparatus for producing an acetal by a monool-air catalytic conversion according to any one of claims 1 to 5, specifically comprising the following step:

Step A: feeding: the air generated by the air generating device (1) is controlled by the mass flow meter (2) to enter the gas preheater (4); the monohydric alcohol in the raw material tank (5) After the feed is controlled by the reciprocating metering pump (7), the liquid preheater (9) is entered;

Step B: heating and mixing: the air heated by the gas preheater (4) is further heated by the gas preheating pipe (10) to enter the gas-liquid mixing preheating pipe (35), and the liquid preheater (9) The heated monohydric alcohol is further heated by the liquid preheating pipe (34) to enter the gas-liquid mixed preheating pipe (35), and the monohydric alcohol and air in the gas-liquid mixed preheating pipe (35) After heating and preliminary mixing, it enters the vaporization mixer (11), and the reheated monohydric alcohol is completely vaporized in the vaporization mixer (11) and thoroughly mixed with the reheated air to obtain a mixed gas;

Step C: catalytic conversion: the mixed gas is heated to a catalytic reaction temperature by the superheating pipe (12), and then enters a reactor (15) packed with an oxidation catalyst to carry out a reaction;

Step D: cooling condensate liquefaction: the reaction tail gas produced by the reactor (15) is transported from the air generating device (1) to the gas preheater in the tube path of the gas preheater (4) (4) The air in the shell side is subjected to primary heat exchange, and then enters the tube path of the liquid preheater (9) and is transported from the raw material tank (5) to the liquid preheater (9) The monohydric alcohol liquid in the shell side undergoes secondary heat exchange, and finally reaches the tube of the cryocooler (22) and is transported from the circulating refrigerator (23) to the shell of the cryocooler (22) The internal chilled liquid is subjected to tertiary heat exchange to obtain a gas-liquid mixture in which the liquid component in the reaction tail gas is completely condensed;

Step E: gas-liquid separation: the gas-liquid mixture condensed by the cryocooler (22) enters the gas-liquid separation tower (24) for separation, and the separated liquid enters the product tank (26), and is separated. The gas is treated separately by the wet flow meter (29).
The method for preparing an acetal by a monool-air catalytic conversion according to claim 6, wherein the acetal is a product of condensation of a monohydric aldehyde corresponding to the monohydric alcohol and the monohydric alcohol, The oxidation catalyst is selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Ce, Zr, Nb, Mo, Ru, Sn, Sb, Ta, W, Os, Ir, Pt, Au catalyst or heteropoly Any one or more of the acid catalysts.
The method for preparing an acetal by a monool-air catalytic conversion according to claim 7, wherein the oxidation catalyst is selected from any one or more of V, Mo, Fe or a heteropolyacid catalyst. species outlet pressure, the air generating means (1) is 0.0MPa-10.5MPa, the monohydric alcohol is a liquid space velocity of 0.1h -1 -3.0h -1, the amount of substance of monohydric alcohols with the air The ratio is 1:50-2:1, the outlet pressure of the reciprocating metering pump (7) is 0.0MPa-10.3MPa, the gas preheating pipe (10), the liquid preheating pipe (34), gas-liquid mixing The temperature of the preheating pipe (35) is 20 ° C - 100 ° C, the temperature of the vaporizing mixer (11) is 30 ° C - 400 ° C, and the temperature of the superheating pipe (12) is 80 ° C - 600 ° C, The temperature in the reactor (15) is 80 ° C - 600 ° C, the back pressure valve (28) control system pressure is 0.0 MPa - 10.0 MPa, and the circulating freezer (23) is used in the temperature range of -40 ° C to 10 ℃, an amount of circulation of the refrigerating liquid is 0.6m 3 /h-4.8m 3 / h.
The method for preparing an acetal by a monool-air catalytic conversion according to claim 8, wherein the monool has a liquid space velocity of 0.3 h -1 -2.5 h -1 , and the monohydric alcohol The ratio of the amount of air to the substance is 1:15-8:5, the temperature in the reactor (15) is 80 ° C -300 ° C, and the pressure of the back pressure valve (28) is 0.0 MPa - 3.0 MPa. the circulation refrigerating machine (23) using a temperature range of -25 to -40 ℃ deg.] C, the refrigerating liquid circulating in an amount of 1.2m 3 /h-4.0m 3 / h.
The method for preparing an acetal by a monool-air catalytic conversion according to claim 9, wherein the liquid separated in the step E comprises water, the monohydric alcohol and the monohydric alcohol. An aldehyde, an acid, a monocarboxylic acid ester, a dialkyl ether, an acetal; the separated gas includes N 2 , O 2 , CO, CO 2 .