CN1301686A - Method for preparing dimethyl ether by methanol dewatering - Google Patents
Method for preparing dimethyl ether by methanol dewatering Download PDFInfo
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- CN1301686A CN1301686A CN 99122907 CN99122907A CN1301686A CN 1301686 A CN1301686 A CN 1301686A CN 99122907 CN99122907 CN 99122907 CN 99122907 A CN99122907 A CN 99122907A CN 1301686 A CN1301686 A CN 1301686A
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Abstract
The present invention is a methanol-dewatering dimethyl ether preparing process by using sulfuric acid modified-kaolin as catalyst. The present invention features that kaolin is produced into acid-modified kaolin through the steps of preparation of homogeneous slurry, addition of 25 % concentration sulfuric acid while heating treatment at 60-100 deg.C for 3-9 hr, addition of water and stagnation to pH 4, suction-filtering, water-washing, drying, cooling and 40-60 mesh sieving; and that methanol is twice vaporized by dried hydrogen gas, preheated at 100 deg.C and dewatered in a reactor. Compared with available production process, the said process has decreased environmental pollution and corrosion, stable catalytic activity at mormal pressure, high methanol converting rate and dimethyl ether selectivity, and greatly reduced production cost.
Description
The invention relates to etherification reaction of methanol dehydration, in particular to a method for preparing dimethyl ether by methanol dehydration by using acid modified kaolin.
Dimethyl ether, i.e. methyl ether, with the structural formula CH3-O-CH3It is an ideal substitute of liquefied fuel gas, and is an important basic chemical raw material, and has extensive application in the fields of pharmacy, dye, pesticide, refrigeration and daily chemical industry, etc.. In the early stage, the dehydrating agent adopted for preparing the dimethyl ether by dehydrating the methanol is concentrated sulfuric acid, the reaction is carried out in a liquid phase, and the process method is urgently to be improved due to serious environmental pollution and corrosion; also useful is the vapor phase dehydration of methanol to dimethyl ether, the traditional industrial production method is to make methanol vapor pass through aluminum phosphate catalyst under the pressure of 350-400 ℃ and 1.5MPa, the temperature of the method is higher, the conversion rate is low: in 1981, Mobil corporation of the united states used HZSM-5 type molecular sieves with a relatively high silica to alumina ratio, which gave a methanol conversion of 70%, but the catalyst was difficult to prepare, and the cost of production was high for industrial applications. In 1991, the Toya chemical company of Mitsui, Japan developed γ -Al having a specific surface area and pore volume2O3As a catalyst for preparing dimethyl ether by dehydrating methanol, the conversion rate of the methanol can reach 80 percent. At present, the modification of kaolin and the exploration of the catalytic activity of the kaolin are vigorously researched at home and abroad, the application research is focused on the catalytic cracking reaction, and the etherification reaction for carrying out acid modification on the kaolin and used for methanol dehydration is not reported yet.
The invention aims to provide a method for preparing dimethyl ether by dehydrating methanol by taking cheap and easily-obtained kaolin as a raw material and taking the kaolin modified by sulfuric acid as a catalyst, which aims to solve the following problems: reducing environmental pollution and corrosion, obtaining long-term stable catalytic activity under normal pressure, improving the conversion rate of methanol, ensuring that the selectivity of dimethyl ether is more than 99 percent, greatly reducing the production cost and the like.
The preparation method comprises the steps of firstly, preparing acid modified kaolin, slowly adding the kaolin into an aqueous solution while stirring to prepare uniform slurry, slowly heating the slurry, and adding H with the relative amount of 0.15-0.60 and the concentration of 25%2SO4Continuously heating, treating at 60-100 deg.C for 3-9 hr, adding water into the reacted slurry, standing until pH =4, pump-filtering, washing, and dryingCooling and sieving the particles with 40-60 meshes to obtain the acid modified kaolin; then the methanol dehydration is used for preparing the dimethyl etherIn the reaction, the dried hydrogen drives methanol to vaporize at the flow rate of 20-130ml/min, the methanol vaporized twice enters a reactor after being preheated at 100 ℃, and methanol dehydration reaction is carried out under the conditions of normal pressure, the temperature of 220-320 ℃, the space velocity of methanol liquid of 0.62-8ml/h and the loading of the catalyst of 0.15 g. The present invention is described in detail below.
The kaolin adopted by the invention is composed of38 percent of alumina (Al)2O3) And 43% silicon dioxide (SiO)2)。
Preparation of acid-modified kaolin
Adding slowly aluminum oxide (Al) into the aqueous solution while stirring2O3) 38% and silicon dioxide (SiO)2) 43% kaolin, making into uniform slurry, slowly heating the slurry, and adding 0.15-0.60 relative amount of 25% H2SO4And continuously heating, treating for 3-9 hours at the temperature of 60-100 ℃, adding water into the slurry after the reaction is finished, standing until the pH =4, performing suction filtration, washing with water, drying, and screening particles of 40-60 meshes to obtain the acid modified kaolin.
Preparation of dimethyl ether by (II) dehydration of methanol
The acid modified kaolin prepared by the method is used as a catalyst in the reaction of preparing dimethyl ether by dehydrating methanol. The principle of methanol gas phase catalysis is that methanol steam passes through a solid acid catalyst to generate gas-solid phase catalytic reaction, and dimethyl ether is generated through dehydration.
(1) The chemical reaction formula for generating the dimethyl ether by methanol dehydration is as follows:
(2) the evaluation of the activity of the catalyst and dimethyl ether preparation by methanol dehydration was carried out in a self-assembled continuous flow micro-reverse-chromatography apparatus under normal pressure (see the attached figure 1).
See FIG. 1, from H2The hydrogen from the steel cylinder 1 is dried by a drying agent 2 and then enters a methanol saturator 5, methanol is driven to vaporize by bubbling of hydrogen, and two methanol saturations areadopted to saturate methanol vaporVaporizing for the second time, controlling hydrogen flow rate within 20-130ml/min with soap powder flowmeter, preheating methanol after twice vaporization to 100 deg.C with preheater 6, introducing into miniature reaction tube 7, and maintaining at normal pressure and temperatureThe methanol dehydration reaction is carried out under the conditions of 220 ℃ and 320 ℃, the methanol liquid space velocity of 0.62-ml/h and the catalyst loading of 0.15 g.
The reactor is a straight stainless steel tube with the inner diameter of 4mm, the reactor is placed in a constant temperature quartz tube, the temperature of the reactor is controlled by a 702 precise temperature controller, and the constant temperature precision is +/-0.5 ℃ when detected by a nickel-chromium-nickel-silicon thermocouple.
The acid-modified kaolin of the present invention was compared to existing catalysts (table 1).
Table 1:
| catalyst type | Methanol conversion (%) | Dimethyl ether selectivity (%) |
| Metal-containing aluminum silicate | 70.0 | ＞90 |
| γ-Al2O3 | 80.0 | 99 |
| α-Al2O3 | 74.9 | 99 |
| Acid modified kaolin (MK-3) | 81.6(300℃) | ＞99 |
| Acid modified kaolin (MK-4) | 85.1(320℃) | ＞99 |
From the comparative data in table 1, it can be seen that: the acid modified kaolin is used as a catalyst for the reaction of preparing the dimethyl ether by dehydrating the methanol, the conversion rate of the methanol can be improved, and the selectivity of the dimethyl ether is more than 99 percent. From the experiments of the present invention, it follows:
1. the kaolin is used for preparing dimethyl ether by methanol dehydration after being modified by sulfuric acid, and the catalytic activity is greatly improved compared with that of the original soil. The conditions of relative acid dosage, treatment time, treatment temperature and the like have great influence on the catalytic performance of the modified kaolin. When the MK-3 catalyst with the relative sulfuric acid dosage of 0.30 has the best activity, the conversion rate of methanol is 81.6 percent at the reaction temperature of 300 ℃, the selectivity of dimethyl ether is more than 99 percent, and the activity stability is also good.
2. The reaction temperature has great influence on the conversion rate of dimethyl ether prepared by methanol dehydration. At a certain residence time, the methanol conversion increases with increasing reaction temperature, and the conversion remains essentially unchanged up to 320 ℃.
Therefore, the method for preparing dimethyl ether by dehydrating methanol by using the acid modified kaolin can reduce environmental pollution and corrosion, can obtain long-term stable catalytic activity under normal pressure, improve the conversion rate of methanol and the selectivity of dimethyl ether, and can greatly reduce the production cost. Acid-modified kaolin (1000 yuan/ton) is an excellent catalyst for preparing dimethyl ether in industry.
The specific embodiment of the invention is as follows:
example 1: adding slowly aluminum oxide (Al) into the aqueous solution while stirring2O3) 38% and silicon dioxide (SiO)2) 43% kaolin, making into uniform slurry, slowly heating to obtain slurry, and adding 25% H with relative amount of 0.602SO4And continuously heating to 60 ℃, treating for 6 hours, adding water into the slurry after the reaction is finished, standing until the pH is about =4, performing suction filtration by a water pump, washing by water, drying, cooling, and screening particles of 40-60 meshes to obtain the acid modified kaolin, which is recorded as MK-1.
The acid-modified kaolin prepared by the above method was subjected to a reaction for producing dimethyl ether by dehydrating methanol according to the above method, and the activity of the catalyst was represented by the conversion of methanol to dimethyl ether, and the measurement results are shown in table 2.
TABLE 2 (Note: dimethyl ether selectivity is greater than 99%)
| Catalyst and process for preparing same | Conversion ratio of methanol (%) | |||||
| 220℃ | 240℃ | 260℃ | 280℃ | 300℃ | 320℃ | |
| MK-1 | 12.4 | 20.3 | 31.5 | 50.3 | 76.7 | 78.3 |
Example 2: the preparation method is the same as example 1. The relative amount of acid was 0.15, the treatment time of the acid was 3 hours, the treatment temperature was 100 ℃ and was recorded as MK-2.
The measurement results of the reaction for producing dimethyl ether by dehydrating methanol according to the above method are shown in Table 3.
TABLE 3 (Note: dimethyl ether selectivity is greater than 99%)
| Catalyst and process for preparing same | Conversion ratio of methanol (%) | |||||
| 220℃ | 240℃ | 260℃ | 280℃ | 300℃ | 320℃ | |
| MK-2 | 3.9 | 16.1 | 28.1 | 46.1 | 66.7 | 77.2 |
Example 3: the preparation method is the same as example 1. The relative amount of acid was 0.3, the treatment time of the acid was 3 hours, the treatment temperature was 80 ℃ and was recorded as MK-3.
The measurement results of the reaction for producing dimethyl ether by dehydrating methanol according to the above method are shown in Table 4.
TABLE 4 (Note: dimethyl ether selectivity is greater than 99%)
| Catalyst and process for preparing same | Conversion ratio of methanol (%) | |||||
| 220℃ | 240℃ | 260℃ | 280℃ | 300℃ | 320℃ | |
| MK-3 | 12.4 | 28.7 | 45.3 | 68.4 | 81.6 | 80.0 |
Meanwhile, the catalyst prepared in this example was subjected to an activity life test to measure the initial maximum methanol conversion and the methanol conversion within 500 hours, and the results are shown in Table 5.
TABLE 5
| Catalyst and process for preparing same | Temperature (. degree.C.) | Initial activity | 120h | 240h | 360h | 500h |
| MK-3 | 318-322 | 80.1 | 74.1 | 74.0 | 73.8 | 73.8 |
Example 4: the preparation method is the same as example 1. The relative amount of acid was 0.60, the acid treatment time was 3 hours, the treatment temperature was 60 ℃ and was recorded as MK-4.
The measurement results of the reaction for producing dimethyl ether by dehydrating methanol according to the above method are shown in Table 6.
TABLE 6 (note: dimethyl ether selectivities are all greater than 99/%)
| Catalyst and process for preparing same | Conversion ratio of methanol (%) | |||||
| 220℃ | 240℃ | 260℃ | 280℃ | 300℃ | 320℃ | |
| MK-4 | 11.5 | 16.8 | 34.4 | 55.4 | 76.6 | 85.1 |
Meanwhile, the catalyst prepared in this example was subjected to an activity life test to measure the initial maximum methanol conversion and the methanol conversion within 500 hours, and the results are shown in Table 7.
TABLE 7 initial activity of catalyst at temperature (. degree. C.) 120h 240h 360h 500 hMK-4318-32285.185.282.980.180.0
Example 5: the preparation method is the same as example 1. The relative amount of acid was 0.60, the acid treatment time was 9 hours, the treatment temperature was 60 ℃ and is denoted as MK-5.
The measurement results of the reaction for producing dimethyl ether by dehydrating methanol according to the above method are shown in Table 8.
TABLE 8 (Note: dimethyl ether selectivity is greater than 99%)
| Catalyst and process for preparing same | Conversion ratio of methanol (%) | |||||
| 220℃ | 240℃ | 260℃ | 280℃ | 300℃ | 320℃ | |
| MK-5 | 8.9 | 19.7 | 33.9 | 52.9 | 74.6 | 80.0 |
Meanwhile, the catalysts prepared in this example were subjected to the active lifetime test to measure the methanol conversion at the initial maximum methanol conversion within 500 hours, and the results are shown in table 9.
TABLE 9
| Catalyst and process for preparing same | Temperature (. degree.C.) | Initial activity | 120h | 240h | 360h | 500h |
| MK-5 | 318-322 | 80.0 | 79.2 | 79.0 | 79.0 | 78.4 |
Description of the drawings: FIG. 1 is a diagram of a reaction apparatus for preparing dimethyl ether by dehydrating methanol, wherein: 1-H2A steel cylinder; 2-a drying agent; 3-a flow stabilizing valve; 4-glass rotameter; 5-methanol feed pipe; 6-a preheater; 7-a micro-reaction tube; 8-a six-way valve; 9-102G gas chromatograph; 10-lead pool power supply and hydrogen flame ion amplifier; 11-one precise temperature controller; 12-a microprocessor processing system; 13-a nickel chromium-nickel silicon precise temperature control instrument; 14-three-way valve.
Claims (1)
1. A method for preparing dimethyl ether by methanol dehydration comprises the preparation of a catalyst and the method for preparing dimethyl ether by methanol dehydration, and is characterized in that:
(1) adding kaolin slowly into the water solution under stirring to obtain uniform slurry, slowly heating the slurry, and adding 0.15-0.60 relative amount of 25% H2SO4And continuously heating, treating for 3-9 hours at the temperature of 60-100 ℃, adding water into the slurry after the reaction is finished, standing until the pH =4, performing suction filtration by a water pump, washing, drying, cooling, and screening particles of 40-60 meshes to obtain the acid modified kaolin.
(2) The dried hydrogen drives methanol to vaporize at the flow rate of 20-130ml/min, the methanol vaporized twice enters a reactor after being preheated at 100 ℃, and methanol dehydration reaction is carried out under the conditions of normal pressure, the temperature of 220-320 ℃, the space velocity of methanol liquid of 0.62-8ml/h and the loading amount of catalyst of 0.15 g.
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| CN 99122907 CN1301686A (en) | 1999-12-24 | 1999-12-24 | Method for preparing dimethyl ether by methanol dewatering |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100366597C (en) * | 2006-07-21 | 2008-02-06 | 新奥新能(北京)科技有限公司 | Process for preparing dimethyl ether |
| US8304582B2 (en) | 2007-03-30 | 2012-11-06 | China Petroleum & Chemical Corporation | Fluidized catalytic process for production of dimethyl ether from methanol |
| US8541630B2 (en) | 2008-03-26 | 2013-09-24 | China Petroleum & Chemical Corporation | Process for producing dimethyl ether from methanol |
| WO2013166985A1 (en) * | 2012-05-11 | 2013-11-14 | Rhodia Operations | Preparation of an ether compound |
-
1999
- 1999-12-24 CN CN 99122907 patent/CN1301686A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100366597C (en) * | 2006-07-21 | 2008-02-06 | 新奥新能(北京)科技有限公司 | Process for preparing dimethyl ether |
| US8304582B2 (en) | 2007-03-30 | 2012-11-06 | China Petroleum & Chemical Corporation | Fluidized catalytic process for production of dimethyl ether from methanol |
| US8541630B2 (en) | 2008-03-26 | 2013-09-24 | China Petroleum & Chemical Corporation | Process for producing dimethyl ether from methanol |
| WO2013166985A1 (en) * | 2012-05-11 | 2013-11-14 | Rhodia Operations | Preparation of an ether compound |
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