Chinese name methyl ether; Dimethyl ether; Oxydimethane

English name dimethyl ether; Methoxymethane

CAS login number 1 15- 10-6

Structure or molecular formula

CH3-O-CH3

All C and O atoms form σ bonds with sp3 hybrid orbitals.

Relative molecular weight or atomic weight 46.07

Molecular formula C2H6O

Density Relative density 1.6 17 (air = 1)

Melting point (℃)- 138.5

Boiling point (℃)-24.5

Flash point (℃)-4 1.4

Vapor pressure (PA) 663 (-101.53℃); 8 1 19(-70.7℃); 2 1905(-55℃)

Character; Role; letter

Colorless flammable gas or compressed liquid, with ether smell.

Dissolution situation

Soluble in water and ethanol.

use

Used as solvent, refrigerant, etc.

Preparation or source

It is obtained by dehydration of methanol or decomposition of orthoformic acid under the catalysis of ferric chloride.

other

The critical temperature is 128.8℃. The critical pressure is 5.32 MPa. Freezing point-138.5℃. Liquid density 0.66 1

Part III: Overview of risks-

Hazard category:

Invasion route:

Health hazard: it has inhibitory effect on the central nervous system and weak anesthetic effect. Inhalation can cause anesthesia and suffocation. Irritating to the skin.

Environmental hazards:

Danger of explosion: This product is flammable and irritating.

Part IV: First aid measures-

Skin contact:

Eye contact:

Inhalation: leave the scene quickly and go to a place with fresh air. Keep the respiratory tract unobstructed. If you have difficulty breathing, give oxygen. If breathing stops, give artificial respiration immediately. See a doctor.

Intake:

Part V: Fire Prevention Measures-

Hazard characteristics: combustible gas. Mixing with air will form an explosive mixture. Contact with heat, Mars, flame or oxidant is easy to burn and explode. When exposed to air or light, peroxide with potential explosion hazard will be produced. Gas is heavier than air, it can spread to a considerable distance at a lower place, and it will catch fire when it meets a fire source. In case of high heat, the internal pressure of the container rises, which is in danger of rupture and explosion.

Harmful combustion products: carbon monoxide and carbon dioxide.

Fire extinguishing method: cut off the gas source. If the gas source cannot be cut off, it is not allowed to extinguish the flame at the leak. Spray water to cool the container, and if possible, move the container from the fire to an open place. Extinguishing agent: atomized water, insoluble foam, dry powder, carbon dioxide, sand.

Part VI: Emergency Treatment of Leakage-

Emergency treatment: quickly evacuate the personnel from the leaked and polluted area to the upwind area, isolate them and strictly restrict access. Cut off the fire. It is recommended that emergency personnel wear self-contained positive pressure breathing apparatus and anti-static work clothes. Cut off the leakage source as much as possible. Cover the sewer and other places near the leakage point with industrial covering or adsorption/absorbent to prevent gas from entering. Reasonable ventilation and accelerated diffusion. Spray water is diluted and dissolved. Build a dike or dig a pit to contain a large amount of wastewater. Leaked containers should be properly treated, repaired and inspected before use.

Part VII: Operation, Disposal and Storage-

Precautions for operation: closed operation and comprehensive ventilation. Operators must be specially trained and strictly abide by the operating procedures. Operators are advised to wear self-priming filter gas masks (half masks), chemical safety glasses, anti-static work clothes and chemical gloves. Stay away from kindling and heat sources, and smoking is strictly prohibited in the workplace. Use explosion-proof ventilation system and equipment. Prevent the gas in the workplace from leaking into the air. Avoid contact with oxidants, acids and halogens. During transmission, gas cylinders and containers must be grounded and bridged to prevent static electricity. Lightly load and unload when handling, so as to prevent the cylinders and accessories from being damaged. Equipped with corresponding varieties and quantities of fire fighting equipment and leakage emergency treatment equipment.

Precautions for storage: Store in a cool and ventilated warehouse. Stay away from fire and heat sources. The reservoir temperature should not exceed 30℃. Should be stored separately from oxidant, acid and halogen, and should not be mixed. Adopt explosion-proof lighting and ventilation facilities. It is forbidden to use mechanical equipment and tools that are easy to generate sparks. The storage area should be equipped with emergency treatment equipment for leakage.

Part VIII: Contact Control/Personal Protection-

occupational exposure limits

China MAC(mg/m3): No standard has been established.

Former Soviet Union MAC(mg/m3): No standard has been formulated.

TLVTN: No standards have been established.

TLVWN: No standard has been established.

Monitoring method:

Engineering control: the production process is closed and fully ventilated.

Respiratory system protection: When the concentration in the air exceeds the standard, it is recommended to wear a self-priming filter gas mask (half mask).

Eye protection: Wear chemical safety glasses.

Physical protection: wear anti-static work clothes.

Hand protection: Wear chemical resistant gloves.

Other protection: Smoking is strictly prohibited in the workplace. Work in storage tanks, confined spaces or other high concentration areas must be supervised.

Part IX: Physical and Chemical Characteristics-

Main ingredients: pure products

Colorless gas, with the peculiar smell of ether.

PH value:

Melting point (℃):- 14 1.5

Boiling point (℃):-23.7

Relative density (water = 1): 0.66

Relative steam density (air = 1): 1.62.

Saturated vapor pressure (kpa): 533.2 (20℃)

Combustion heat (kj/mol): 1453.

Critical temperature (℃): 127

Critical pressure (MPa): 5.33

Logarithmic value of octanol/water partition coefficient: No data available.

Flash point (℃): meaningless

Ignition temperature (℃): 350℃

Upper explosion limit% (volume/volume): 27.0

Lower explosive limit% (volume/volume): 3.4

Solubility: Soluble in water, ethanol and ether.

Main uses: used as refrigerant, solvent, extractant, catalyst and polymer stabilizer.

Other physical and chemical properties:

Part X: Stability and Reactivity-

Stability:

Prohibited compounds: strong oxidant, strong acid and halogen.

Conditions for avoiding contact:

Aggregation danger:

Decomposition products:

Part XI: Toxicological data-

Acute toxicity: LD50: No data available.

LC50: 308,000 mg/m3 (inhaled by rats)

Subacute and chronic toxicity:

Irritant:

Sensitization:

Mutagenicity:

Teratogenicity:

Carcinogenicity:

Part XII: Ecological Data-

Eco-toxicological toxicity:

Biodegradability:

Non-biodegradable:

Bioaccumulation or bioaccumulation:

Other harmful effects: No data.

Part XIII: Abandonment and Disposal-

Nature of waste:

Disposal method of waste: refer to relevant national and local laws and regulations before disposal. Incineration is recommended.

Abandoned preventive measures:

Part XIV: Traffic Information-

Dangerous goods number: 2 1040

Un number: 1033

Packaging mark:

Packing category: O52

Packing: steel cylinder; Ordinary wooden cases outside frosted glass bottles or threaded glass bottles; Ordinary wooden box outside ampoule.

Precautions for transportation: the safety helmet on the cylinder must be worn when transporting the cylinder. Cylinders are generally flat, and the bottle mouths should be in the same direction and cannot cross; The height shall not exceed the vehicle guardrail, and it shall be fastened with triangular wooden mats to prevent rolling. Transport vehicles should be equipped with corresponding varieties and quantities of fire fighting equipment during transportation. The exhaust pipe of the vehicle carrying this article must be equipped with a fire retardant device, and it is forbidden to use mechanical equipment and tools that are easy to generate sparks for loading and unloading. Mixed transportation with oxidants, acids, halogens and edible chemicals is prohibited. It should be transported in the morning and evening in summer to prevent sun exposure. Stay away from fire and heat sources during stopovers. Highway transportation should follow the prescribed route, and it is forbidden to stay in residential areas and densely populated areas. When transporting by rail, it is forbidden to slip.

Part XV: Regulatory Information-

Regulatory information: Regulations on the Safety Management of Hazardous Chemicals (promulgated by the State Council 1987 in February), Detailed Rules for the Implementation of the Regulations on the Safety Management of Hazardous Chemicals (Hua Laofa [1992] No.677) and Regulations on the Safe Use of Chemicals in the Workplace (issued by the Ministry of Labor [1996] 427). Classification and Labeling of Commonly Used Hazardous Chemicals (GB 13690-92) classifies this substance as Class 2. 1 combustible gas.

Part XVI: Other information-

References:

Filling department:

Data audit unit:

Version description:

Other information:

supplement

Dimethyl ether, also called dimethyl ether for short, is a colorless gas or compressed liquid at atmospheric pressure, with a slight ether smell. The relative density (20℃) is 0.666, the melting point is-14 1.5℃, the boiling point is -24.9℃, and the vapor pressure at room temperature is about 0.5MPa, which is similar to that of liquefied petroleum gas. Soluble in water and organic solvents such as ethanol, ether, acetone and chloroform. Combustible, the flame is slightly bright when burning, and the combustion heat (gas) is 1455kJ/mol. DME is inert at room temperature, not easy to automatically oxidize, non-corrosive and non-carcinogenic, but it can be decomposed into methane, ethane and formaldehyde under radiation or heating conditions.

Dimethyl ether is a homologue of ether, but unlike ether used as an anesthetic, its toxicity is extremely low. Can dissolve various chemicals; Because of its easy compression, condensation, gasification and mutual solubility with various polar or nonpolar solvents, it is widely used in aerosol products, freon instead of refrigerants, solvents and so on. , can also be used for chemical synthesis, and has a wide range of uses.

As a new basic chemical raw material, dimethyl ether has many unique uses in medicine, fuel, pesticide and other chemical industries because of its good characteristics of easy compression, easy condensation and easy vaporization. For example, high-purity dimethyl ether can replace freon as aerosol propellant and refrigerant, which can reduce the pollution to the atmospheric environment and damage to the ozone layer. Because of its good water solubility and oil solubility, its application range is far superior to that of petrochemical products such as propane and butane. Replacing methanol as a new raw material for formaldehyde production can obviously reduce the production cost of formaldehyde, which shows its superiority in large-scale formaldehyde plant. As a civil gas, its storage, transportation and combustion safety, premixed gas calorific value and theoretical combustion temperature are better than those of liquefied petroleum gas, and it can be used as a mixture of peak shaving gas and liquefied petroleum gas in urban pipeline gas. It is also an ideal fuel for diesel engines. Compared with methanol-fueled vehicles, there is no cold start problem. It is also one of the main raw materials for preparing low-carbon olefins in the future.

Dimethyl ether can also replace diesel as fuel. At present, the main problems to be solved are the corrosion of dimethyl ether to plastic substances and the transformation of diesel engine oil circuit.

At present, dimethyl ether is mainly used as propellant, refrigerant and foaming agent. Secondly, it is used as a chemical raw material to produce a variety of organic chemicals. Such as dimethyl sulfate, alkyl halide, N, N- dimethylaniline, methyl acetate, acetic anhydride, dimethyl carbonate, dimethyl sulfide, ethylene glycol dimethyl ether series ether, etc.

Dimethyl ether is easy to compress and store, with high combustion efficiency and little pollution, and can replace coal gas and liquefied petroleum gas as civil fuel. At the same time, dimethyl ether has a high cetane number and can be directly used as automobile fuel to replace diesel. Dimethyl ether, as a clean fuel, has great development potential and has been widely concerned at home and abroad.

1 Market analysis at home and abroad

1. 1 foreign market analysis

At present, the production of dimethyl ether in the world is mainly concentrated in the United States, Germany, the Netherlands and Japan. In 2002, the global (excluding China, the same below) total production capacity was 208,000 tons/year, the output was 6,543.8+0.5 million tons, and the operating rate was 72%. The main foreign producers of dimethyl ether are American Dopnt Company, Dutch AKZO Company, German DEA Company and United Rheinland Lignite Fuel Company, among which German DEA Company has the largest production capacity of 65,000 tons/year.

Major dimethyl ether producers in the world

Name of serial number of manufacturer's production capacity (10,000 tons/year)

1 dopt (USA) 3.0

2 DEA (Germany) 6.5

3 United Rheinland Lignite Fuel (Germany) 3.0

4 AKZO (Netherlands)

5 Sumitomo (Japan) 1.0

6 DEA (Australia) 1.0

7 Mitsui Dongjin (Japan)

8 Kang Sheng (Japan) 1.8

9 NKK (Japan) 1.0

Total 20.8

Due to the huge market demand potential of dimethyl ether, the construction of dimethyl ether has become a hot spot in the world, and some large-scale dimethyl ether plants are already under construction.

Dimethyl ether development company (a consortium composed of Total Fina Elf and 8 Japanese companies) plans to build a commercial dimethyl ether plant with a capacity of 2,500 tons/day. Japan Toyo Engineering Company has completed the feasibility verification of building a single series of 2.5 million tons/year dimethyl ether plant in the Middle East, and it is expected that the plant will be completed in 2005-2006. BP, India Natural Gas Administration and India Petroleum Company will invest 600 million US dollars to build a 65.438+800,000 tons/year commercial dimethyl ether production plant to replace naphtha, diesel oil and liquefied petroleum gas. The construction project started in 2002 and is scheduled to be put into production in 2004. A joint venture company composed of Japanese consortia (Mitsubishi Gas Chemical Corporation, Japan Airlines, Mitsubishi Heavy Industries Corporation and Itochu Corporation) will build a large dimethyl ether plant in Australia with a capacity of1.4-24,000 tons/year, which is scheduled to be put into operation in 2006.

At present, the main consumption field of dimethyl ether is as a solvent and aerosol propellant, and the consumption in other aspects is not much. In 2002, the consumption of dimethyl ether in the world was 6.5438+500,000 tons/year, and the demand is expected to be around 200,000 tons/year by 2005.

Dimethyl ether is an excellent, safe and clean chemical product, and its development prospect is generally optimistic. More importantly, as a new and clean civil and vehicle fuel, it is regarded as an excellent substitute for diesel or LPG/CNG, and its market demand as a fuel will increase dramatically.

In 2000, there were 4 million LPG vehicles, 4 million ethanol vehicles, 1 10,000 CNG vehicles and some methanol vehicles in the world. Take the United States as an example In 2000, 420,000 cars in the United States used alternative fuels. It is estimated that by 2005, the number of vehicles using alternative fuels (LPG and CNG) in the United States will reach 165438+ million, 3.3 million in 20 10, and 5.5 million in 20 15.

At present, the consumption of alternative fuels in the United States is about 6.5438+0 million tons (352× 654.38+0.06 gallon equivalent gasoline), accounting for about 0.2% of the total fuel consumption in that year. If the proportion of alternative fuels in the United States is increased to 5%, its demand will reach 25 million tons, which shows that the market prospect of alternative fuels is considerable.

Asia is the fastest growing region of diesel consumption in the world. According to the forecast of foreign research institutions, the annual demand for dimethyl ether as an alternative fuel in Asia will reach 30 million tons in 2005. It can be seen that dimethyl ether will become the main alternative fuel of diesel because of its incomparable advantages over other alternative fuels, and it has an immeasurable market prospect.

1.2 domestic market analysis

In recent years, the production of dimethyl ether in China has developed rapidly. At present, there are more than a dozen production enterprises. In 2002, the total production capacity was 3 1.8 million tons/year, and the output was about 20,000 tons, with a low operating rate of about 63%.

Main dimethyl ether production enterprises and production capacity in China (unit: ton/year)

Serial number manufacturer name production capacity

1 Jiangsu Wuxian Synthetic Chemical Plant 2000

2 Guangdong Zhongshan Kaida Fine Chemical Co., Ltd. 5000

Chengdu Huayang Weiyuan Natural Gas Chemical Plant 2000

4 Shanghai Petrochemical Research Institute 800

5 Kunshan, Jiangsu 1000

6 Shaanxi New Gas Appliance Company 5000

7 Mengcheng Chemical Fertilizer Plant, Anhui Province, 2500

8 Zhejiang Zhuji Xinya Chemical Company 1000

9 Guangdong Jiangmen Nitrogen Fertilizer Plant 2500

10 Zhejiang Yiwu Yangguang Chemical Co., Ltd. 2500

1 1 Shanghai Shenwei Aerosol Company 1000

12

Shandong Jiutai Chemical Technology Co., Ltd. 5000

13 Hubei Tian Li industrial co., ltd. 1500

Total 3 1800

In recent years, the construction of dimethyl ether in China has become a craze, and several companies plan to introduce technology through joint ventures and cooperation to build large-scale dimethyl ether production plants.

The main projects under construction or proposed are as follows:

In April of 20001year, Shaanxi Xinran gas appliance Co., Ltd. and American Zhaoyun Resources Co., Ltd. signed a project agreement to jointly develop "200,000 tons/year coal-based one-step synthesis of dimethyl ether ultra-clean fuel", with a total investment of 2.03 billion yuan, with the US contributing 90%.

Ningxia 830,000 tons/year coal-based dimethyl ether project plans to invest 4.78 billion yuan, and plans to use foreign capital. Signed a cooperation agreement with Magnet United Company, relying on the technology of American Aerodynamics Company.

Sichuan Luzhou Natural Gas Co., Ltd. has built a two-step dimethyl ether plant with a capacity of 654.38+100000 tons/year, and the second dimethyl ether plant with a capacity of 654.38+100000 tons/year has also started construction.

Shandong Linyi Minglu Chemical Co., Ltd. is building a 30,000-ton/year dimethyl ether plant, adopting the self-developed liquid-phase two-step process technology.

The dimethyl ether project of Shandong Huaxing Group with an annual output of 30,000 tons/year started in August 2004. The factory adopts two-step method.

Shandong Yankuang Group Corporation plans to build a 600,000-ton dimethyl ether plant and introduce foreign one-step dimethyl ether technology.

In addition, many places in China have proposed to build DME plants, such as Southwest Petroleum and Natural Gas Administration, Xinjiang, Shuangyashan in Heilongjiang, Daqing Oilfield, Shaanxi, Lanzhou and Anhui.

Dimethyl ether is mainly used as propellant of aerosol, aerosol and spraying agent in China, and it consumes 0.8 million tons of dimethyl ether/kloc-0 every year. Due to the rapid development of aerosol industry in China, it is estimated that about 30,000 tons of dimethyl ether will be needed in 2005 and 40,000 tons in 20 10. In addition, the consumption of dimethyl ether used to synthesize dimethyl sulfate and other chemical products in China is about 1. 1 10,000 tons.

Dimethyl ether can replace natural gas, coal gas and liquefied petroleum gas as civil fuel, because its properties are similar to liquefied petroleum gas and it is easy to store and compress. In 2002, the apparent consumption of liquefied petroleum gas in China was16.2 million tons. At the same time, China began to import a large number of liquefied petroleum gas from 654.38+0990, and the import volume of liquefied petroleum gas in 2002 was 6.26 million tons. If the price of dimethyl ether is appropriate, assuming that dimethyl ether replaces imported liquefied petroleum gas, based on the current import volume, it needs fuel-grade dimethyl ether about100000 tons. With the continuous improvement of people's living standards, the demand for civil fuels will increase greatly, especially for clean energy such as natural gas, dimethyl ether and liquefied petroleum gas. Therefore, the development prospect of dimethyl ether as civil fuel is very bright.

Dimethyl ether has excellent fuel characteristics, such as convenience, cleanness, high cetane number, good power performance, less pollution and easy storage as liquid under slight pressure. As an alternative fuel for vehicle diesel, it has incomparable comprehensive advantages such as liquefied gasoline, natural gas, methanol and ethanol.

In 2002, China's diesel consumption was 76.62 million tons, and the diesel consumption increased rapidly. It is estimated that the consumption will reach 82.9 million tons in 2005 and 10 1 10,000 tons in 2006. Dimethyl ether, as a good alternative fuel for diesel, needs about 5.53 million tons of dimethyl ether in 2005 and 6.74 million tons in 20 10 according to its replacement rate of 5%.

To sum up, it is estimated that the demand for dimethyl ether in aerosol and chemical industries in China will reach 50,000-60,000 tons in 2005. The consumption of dimethyl ether as alternative fuel mainly depends on the supply of dimethyl ether. If the price of dimethyl ether drops to a level that can compete with diesel or liquefied petroleum gas, it is believed that the consumption of dimethyl ether as fuel will increase rapidly and the market scale will be quite amazing.

2 process technology analysis

The production methods of dimethyl ether include one-step method and two-step method. One-step method refers to the one-step synthesis of dimethyl ether from raw gas, and two-step method refers to the synthesis of methanol from synthetic gas and then dehydration to prepare dimethyl ether.

● One step method

In this method, after the natural gas is converted or gasified to generate synthesis gas, the synthesis gas enters the synthesis reactor, and the two reaction processes of methanol synthesis and methanol dehydration and the shift reaction are completed simultaneously in the reactor. The product is a mixture of methanol and dimethyl ether, and the mixture is separated by a distillation device to obtain dimethyl ether, and unreacted methanol is returned to the synthesis reactor.

One-step method mostly adopts bifunctional catalysts, which are generally formed by physical mixing of two types of catalysts. One is methanol synthesis catalysts, such as Cu-Zn-Al(O)-based catalysts, BASFS3-85 and ICI-5 12, etc. The other is methanol dehydration catalyst, such as alumina, porous SiO _ 2-Al _ 2O _ 3, Y-type molecular sieve, ZSM-5 molecular sieve and mordenite.

● Two-step method

The method is divided into two steps, that is, methanol is synthesized from synthesis gas, and methanol is dehydrated into dimethyl ether under the action of solid catalyst. ZSM-5 molecular sieve containing γ-al2o 3/SiO 2 is commonly used as dehydration catalyst at home and abroad. The reaction temperature is controlled at 280~340℃ and the pressure is 0.5 ~ 0.8 MPa. The one-way conversion of methanol is between 70-85%, and the selectivity of dimethyl ether is greater than 98%.

One-step synthesis of dimethyl ether has no intermediate process of methanol synthesis. Compared with the two-step synthesis method, it has the advantages of simple process, less equipment, less investment and low operating cost, thus reducing the production cost of dimethyl ether and improving economic benefits. Therefore, one-step synthesis of dimethyl ether is a hot topic at home and abroad. The representative one-step processes developed abroad are: Danish Topsφe process, American Air Products process and Japanese NKK process.

Two-step synthesis of dimethyl ether is the main process of dimethyl ether production at home and abroad. This method takes refined methanol as raw material, with few by-products of dehydration reaction, and the purity of dimethyl ether reaches 99.9%. Mature process, wide equipment adaptability and simple post-treatment. It can be built directly in methanol production plants or in other non-methanol production plants with good public facilities. However, this method has to go through methanol synthesis, methanol rectification, methanol dehydration and dimethyl ether rectification, with long process and large equipment investment. However, at present, most of the large-scale dimethyl ether construction projects announced abroad adopt two-step process technology, which shows that the two-step process has strong comprehensive competitiveness.

2. 1 Main foreign technologies

(1)Topsφe process

Topsφe's one-step synthesis gas process is a new technology specially developed for natural gas raw materials. An autothermal converter (ATR) is used in the gasification part of the process. Autothermal converter consists of high-pressure reactor with refractory lining, combustion chamber and catalyst bed.

Dimethyl ether synthesis adopts multistage adiabatic reactor with built-in interstage cooling to obtain high conversion rate of CO and CO2. The catalyst is a mixed bifunctional catalyst for methanol synthesis and dehydration to dimethyl ether.

Dimethyl ether synthesis adopts spherical reactor, and a single set of production capacity can reach 7200 tons/day dimethyl ether. The operating conditions of Topsφe process are 4.2MPa and 240 ~ 290℃.

At present, no commercial device has been manufactured for this method. 1995, Topsφe established a 50kg/d pilot plant in Copenhagen, Denmark, to test the process performance.

(2) The new process of liquid dimethyl ether (LPDMETM) consists of 2) air products.

With the support of the U.S. Department of Energy, as part of the clean coal and alternative fuel technology development plan, Air products Company successfully developed a new liquid dimethyl ether process, abbreviated as LPDMETM.

The main advantage of LPDMETM process is to abandon the traditional gas-phase fixed bed reactor and adopt slurry bubble column reactor. The catalyst particles are slurry in the form of fine powder with inert mineral oil. High-pressure synthesis gas raw materials are sprayed and bubbled from the bottom of the tower, and solid catalyst particles and gas feed are fully mixed. The use of mineral oil makes the mixing more complete, isothermal operation and easy temperature control.

Dimethyl ether synthesis reactor uses built-in cooling pipe to take heat and generate steam at the same time. The loading and unloading of the catalyst in the slurry reactor is easy and there is no need to stop work. Moreover, due to isothermal operation, there is no hot spot problem in the reactor, and the deactivation rate of the catalyst is greatly reduced.

Typical reactor operating parameters are: pressure 2.76 ~ 10.34 MPa, recommended 5.17 MPa; ; Temperature is 200 ~ 350℃, and 250℃ is recommended. The dosage of catalyst is 5% ~ 60% of mineral oil, preferably 5% ~ 25%. In this process, co-rich coal-based syngas has more advantages than natural gas syngas. However, natural gas can also be used as raw material to obtain higher yield. Air Products Company tested the process in a pilot plant with a production capacity of 15t/ day, and the results were satisfactory, but a large-scale industrial plant has not yet been built.

(3) One-step liquid-phase process of NKK Company in Japan.

In addition to air products, NKK Company of Japan has also developed a new process of one-step synthesis of dimethyl ether from syngas in slurry bed reactor.

Raw materials can be natural gas, coal, liquefied petroleum gas, etc. The first step in this process is to make gas. The synthesis gas is cooled and compressed to 5 ~ 7 MPa, and then enters the CO2 absorption tower to remove CO2. The decarbonized raw syngas is desulfurized by activated carbon adsorption tower, and enters the bottom of the reactor after heat exchange to 200℃. The synthesis gas bubbles in the slurry composed of catalyst and mineral oil in the reactor to generate dimethyl ether, methanol and CO2. The product from that reactor is cool, fractionated and separate into dimethyl ether, methanol and water. Unreacted synthesis gas is recycled back to the reactor. After fractionation, high-purity dimethyl ether products (95% ~ 99%) can be obtained at the top of the tower, and crude products composed of methanol, dimethyl ether and water can be obtained at the bottom of the tower. Using NKK technology, a semi-industrial plant with 65,438+0,000 tons/year synthesis gas to produce dimethyl ether by one-step method was built in Niigata.

2.2 Domestic technical and scientific research

In China, the development of technology and catalyst for the production of dimethyl ether from gas-phase methanol (two-step method) began in the 1990s, and industrial production facilities were established soon. In recent years, with the upsurge of dimethyl ether construction, the two-step dimethyl ether process technology in China has been further developed, and the process technology has approached or reached the advanced level abroad.

Shandong Jiutai Chemical Technology Co., Ltd. (formerly Linyi Minglu Chemical Co., Ltd.) successfully developed a liquid-phase composite acid dehydration catalytic production process with independent intellectual property rights, and built a 5000-ton/year production device. After more than a year of production practice, the technology is mature and reliable. The company's second set of 30,000 tons/year devices will also be put into production.

Shandong Jiutai dimethyl ether technology has passed the appraisal organized by the Science and Technology Department of Shandong Province, and is recognized as reaching the international level. In particular, the development of liquid-phase composite acid dehydration catalyst and condensation separation technology overcome the shortcomings of high cost and large investment in one-step synthesis and gas-phase dehydration purification, so that the reaction and dehydration can be carried out continuously, reducing equipment corrosion and equipment investment. The total recovery rate is above 99.5%, the product purity is not lower than 99.9%, and the production cost is greatly reduced compared with gas phase dehydration.

In August 2003, a two-step 10,000-ton dimethyl ether production plant jointly developed by Lu Tianhua and Toyo Engineering Company of Japan was successfully put into trial operation. The process flow of the device is reasonable, the operating conditions are optimized, and it has the characteristics of high product purity, low material consumption and low energy consumption, and it is at the advanced level in China in terms of process level, product quality and automatic operation of equipment and hardware.

In recent years, the technical development of one-step synthesis of dimethyl ether from syngas in China is also very active, and some scientific research institutes and universities have made great progress.

Blue Flower Research Institute, Blue Flower Fertilizer Plant and Lanzhou Chemical Industry Research Institute jointly carried out a pilot study on the production of dimethyl ether from 5mL syngas, focusing on process research, catalyst preparation, activity and life. Good results have been obtained: the COnversion rate of co >; 85%; Selectivity >; 99%。 Two long-term tests (500h, 1000h) show that the developed catalyst has good stability in industrial raw material synthesis gas; The selectivity of dimethyl ether to organic matter >: 97%; Carbon monoxide conversion rate >; 75%; Dimethyl ether product purity >: 99.5%; The total yield of dimethyl ether was 98.45%.

The direct synthesis of dimethyl ether from syngas was systematically studied by Dalian Institute of Chemistry, China Academy of Sciences. SD 2 19-ⅰ, SD 2 19-ⅱ and SD 2 19-ⅲ catalysts were screened out, all of which showed good catalytic performance. The conversion of CO reaches 90%, and the selectivity of dimethyl ether in oxygenated organic matter is close to 100%.

Tsinghua University is also studying one-step dimethyl ether. In the slurry bed reactor, the bifunctional catalyst LP+Al2O3 was used. Under the conditions of 260-290℃ and 4-6MPa, the one-way conversion of CO reaches 55%-65%, and the selectivity of dimethyl ether is 90%-94%.

At present, Zhejiang University, Shanxi Institute of Coal Chemistry, Southwest Research Institute of Chemical Technology, East China University of Science and Technology and other domestic units are also committed to the study of one-step synthesis of dimethyl ether from syngas.

Hangzhou University uses self-made dimethyl ether catalyst and semi-water gas existing in synthetic ammonia plant to synthesize dimethyl ether in one step at a certain reaction temperature, pressure and airspeed. The one-way conversion rate of co reaches 60% ~ 83%, and the selectivity reaches 95%. This technology has built an industrial plant with an annual output of10.5 million tons of dimethyl ether in Tian Li Company, Hubei Province. The device can not only produce alcohol ether fuel, but also produce more than 99.9% high-purity dimethyl ether, and the conversion rate of carbon monoxide is 70%-80%. This is the first domestic industrial production device for directly producing high-purity dimethyl ether from synthetic gas.

For the two-step dimethyl ether process technology, whether it is gas phase method or liquid phase method, the domestic technology has reached an advanced, mature and reliable level, and it is fully qualified to build a large-scale production device.

The technology of one-step gas phase synthesis of dimethyl ether from syngas developed in China is basically mature, and a thousand-ton plant has been built. However, for the construction of large-scale dimethyl ether plant, domestic technology needs to be verified by practice.

3 Conclusions and suggestions

As a clean alternative fuel, dimethyl ether has been widely concerned at home and abroad, especially its huge market potential in replacing natural gas, liquefied petroleum gas and diesel oil, which is of great practical significance to the adjustment of energy structure and environmental protection in China.

Dimethyl ether technology is one of the hot spots in the development of technology at home and abroad. One-step process has the advantages of simple process, less equipment, less investment, lower operation cost and production cost. However, due to the complex synthesis reaction and separation process, it has not been fully industrialized at present. Two-step process is the main process of dimethyl ether production at home and abroad, with high product purity, mature process, wide adaptability and strong comprehensive competitiveness, but it also has the disadvantages of long process and large equipment investment.

At present, popularization and application is the key to the development of dimethyl ether. As a clean alternative energy source, dimethyl ether needs the strong support and help of the government. It is suggested that the state should make overall plans to build large-scale dimethyl ether production bases in areas rich in coal resources but without oil and gas resources. Take dimethyl ether instead of gas and liquefied petroleum gas as the guide of market promotion, and at the same time vigorously strengthen the research of dimethyl ether instead of diesel oil, and comprehensively promote the production and use of dimethyl ether. It is predicted that dimethyl ether will become an important part of China's energy structure in the near future. I hope it helps you!