Method for preparing low-carbon olefin by using methanol and molecular sieve under mechanochemical conditions
By using methanol and zeolite molecular sieve to conduct ball milling reaction under mechanochemical conditions, the problems of high reaction conditions, large energy consumption and catalyst carbon deposits in the existing methanol-to-olefin process are solved, and high efficiency, green preparation and cost savings of low-carbon olefins are achieved. Improves the yield and selectivity of low-carbon olefins.
Patent Information
- Application Number
- CN202411290634.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-14
- Publication Date
- 2024-12-13
AI Technical Summary
The existing methanol-based olefin process has high reaction conditions, high energy consumption, complex equipment and high cost, serious problems with catalyst carbon deposits, and low-carbon olefins are low selectivity, making it difficult to meet the improvement of market demand.
Under mechanochemical conditions, ball milling reaction is carried out using methanol and zeolite molecular sieve (such as ZSM-5, SAPO-34) to prepare low-carbon olefins. The reaction temperature is at room temperature and the ball mill speed is 100-700 r/min. By adjusting the ball mill conditions and The molecular sieve ratio achieves efficient preparation of low-carbon olefins.
The gentle preparation of low-carbon olefins is achieved, the process is green and pollution-free, and the raw materials are recycled, which reduces costs and improves the yield and selectivity of low-carbon olefins.
Smart Images
Figure CN119118765A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of light olefin preparation, and in particular to a method for preparing light olefin by using methanol and molecular sieve under mechanochemical conditions. Background Art
[0002] Low-carbon olefins such as propylene and ethylene are very basic petrochemical raw materials. They can be used to produce products such as ethanol, ethylbenzene, and acetone. They are also synthetic monomers for polyethylene and polypropylene, and are important materials for the manufacture of many daily necessities. The traditional industrial method for synthesizing low-carbon olefins is mainly the cracking of naphtha. Based on the strategy of efficient use of energy, vigorously developing new processes is an important measure to address energy issues. Among them, the methanol to olefins process (MTO, MTP) has the advantages of flexible ethylene and propylene ratios, higher selectivity for light olefins, and mild reaction conditions. It is considered to be an excellent process for C1 chemical synthesis.
[0003] MTO and MTP processes refer to chemical technologies that use methanol synthesized from coal or natural gas as raw materials and produce low-carbon olefins in the form of fluidized bed reactions. The MTO process can be traced back to the 1920s when German scientists Fisher and Tropsch used synthesis gas to produce low-carbon olefins with the help of FT synthesis, but did not achieve ideal results. By the 1990s, the United States successfully developed the UOP / Hydro process unit, and its low-carbon olefin yield reached 80%. With the increasing market demand for low-carbon olefins, the MTO process has been further optimized. For example, Sinopec Shanghai Petrochemical Research Institute and Tsinghua University have improved the existing process and changed the form of catalyst raw material utilization for preparing low-carbon olefins from methanol to parallel type, thereby reducing side reactions and reducing the workload of subsequent processing. This method significantly improves the yield of low-carbon olefins. The catalyst used in the methanol to olefins process is mainly zeolite molecular sieves, of which ZSM-5 and SAPO-34 zeolite molecular sieves are currently the best and most widely used catalysts.
[0004] However, the reaction temperature of the existing MTO process is between 300 and 600 ° C, and the pressure is between 0.01 and 2.0 MPa. The reaction conditions are high, the process energy consumption is large, the equipment requirements and costs are high, and the reaction equipment structure is complex and the operation flexibility is small. The problem of catalyst carbon deposition during the reaction is relatively common, the selectivity for the target low-carbon olefins is low, and the process operation and maintenance costs are high. On the other hand, mechanochemistry is one of the research hotspots of chemical reaction intensification, and is particularly suitable for the activation of lattice catalysts. With the help of high-intensity impact force and shear stress in mechanochemistry, a local high temperature and high pressure environment can be generated, which can cause deformation and fragmentation of the material lattice structure, resulting in lattice defects with high reactivity, thereby greatly improving the catalytic activity of the catalyst. In addition, mechanochemical reactions usually have low reaction conditions, simple equipment, and large operational flexibility, which are easy to achieve large-scale industrial applications. Summary of the invention
[0005] Based on the above background technology, the present invention has developed a method for preparing light olefins using methanol and zeolite molecular sieves under mechanochemical conditions. The process is carried out at room temperature and achieves the preparation of light olefins. The present invention realizes the preparation of light olefins under mechanochemical conditions for the first time and provides a new approach for the methanol to olefin process, which has important practical significance and industrialization potential.
[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing light olefins by using methanol and molecular sieves under mechanochemical conditions comprises the following steps: (1) Mixing methanol and molecular sieve to obtain a mixture, then adding the mixture into a ball milling tank of a ball mill once or multiple times, and subjecting the mixture to ball milling reaction for 1 to 7 hours under vacuum conditions to obtain a reaction product; (2) After the reaction is completed, light olefin gas is obtained in the gas phase through separation.
[0007] Furthermore, the ball mill includes but is not limited to a vibrating ball mill, a stirring ball mill, a drum ball mill and a planetary ball mill.
[0008] Furthermore, the molecular sieve is a combination of one or more of ZSM-5, SAPO-34, MCM-41, and SAPO-11 in any proportion; the molecular sieve has the function of preparing a catalyst for light olefins.
[0009] Furthermore, the mass ratio of the molecular sieve to methanol is 0.1 to 3:30.
[0010] Furthermore, the mass ratio of the stainless steel grinding balls to methanol is 1-100:1.
[0011] Furthermore, the reaction temperature is room temperature, and the ball milling rate is 100-700 r / min.
[0012] In the process of preparing light olefins using methanol and molecular sieves under mechanochemical conditions, the main influencing factors are the ball mill speed, the mass ratio of molecular sieve to methanol, and the total ball milling reaction time. Some examples of preparing light olefins under different conditions are shown in Table 1: Table 1 Summary of methanol conversion, ethylene yield and ethylene selectivity under different preparation conditions serial number raw material equipment condition Methanol conversion rate (%) Ethylene yield (%) Ethylene selectivity (%) 1 ZSM-5, methanol Planetary ball mill 1 h, methanol mass: molecular sieve mass = 30:1, 600 r / min / / / 2 ZSM-5, methanol Stirring ball mill 3 h, methanol mass: molecular sieve mass = 10:1, 600 r / min 18.6 21.3 80 3 ZSM-5, methanol Planetary ball mill 6 h, methanol mass: molecular sieve mass = 30:1, 600 r / min 48.3 47.1 94.4 4 ZSM-5, methanol Stirring ball mill 7 h, methanol mass: molecular sieve mass = 10:1, 600 r / min 51.8 54.2 91.7 5 ZSM-5, SAPO-34 mixed, methanol Planetary ball mill 7 h, methanol mass: molecular sieve mass = 30:1, 600 r / min 47.5 49.3 90.0 6 SAPO-11, methanol Planetary ball mill 6 h, methanol mass: molecular sieve mass = 30:1, 500 r / min 48.7 48.5 92.3 7 MCM-41, methanol Drum ball mill 7 h, methanol mass: molecular sieve mass = 15:1, 400 r / min 46.2 47.3 90.9 8 SAPO-34, Methanol Planetary ball mill 6 h, methanol mass: molecular sieve mass = 30:1, 600 r / min 52.8 53.4 94.8 9 SAPO-34, Methanol Planetary ball mill 6 h, methanol mass: molecular sieve mass = 10:1, 500 r / min 49.7 49.3 94.4 Beneficial effects of the present invention: The process of preparing low-carbon olefins using methanol and molecular sieves under mechanochemical conditions has mild preparation conditions and is green and pollution-free. Secondly, the mixture after the reaction is taken out and rotary evaporated, and the liquid phase is still methanol, which realizes the recycling of raw materials and saves costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention will be further described below in conjunction with the accompanying drawings.
[0014] Figure 1 It is a simplified flow chart of the preparation of light olefins using methanol and molecular sieves under mechanochemical conditions; Figure 2 is the GCMS spectrum of the gas prepared in Example 1; Figure 3 It is a visual diagram of the gas prepared in Example 1 causing the acidic potassium permanganate and bromine carbon tetrachloride solution to fade; Figure 4 This is the liquid phase GC spectrum after the reaction of Example 1; Figure 5 is the GCMS spectrum of the gas prepared in Example 2; Figure 6 This is the liquid phase GC spectrum after the reaction of Example 2; Figure 7 This is the liquid phase GC spectrum after the reaction of Example 3; Figure 8 is the GCMS spectrum of the gas prepared in Example 5; Fig. 9 It is a visual diagram of the gas prepared in Example 5 causing the acidic potassium permanganate and bromine carbon tetrachloride solution to fade; Fig.10 This is the liquid phase GC spectrum after the reaction of Example 5. DETAILED DESCRIPTION
[0015] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0016] Example 1 This embodiment provides a method for preparing light olefins using methanol and ZSM-5 molecular sieve under mechanochemical conditions. The schematic diagram of the preparation process is shown in Figure 1 The detailed preparation steps are as follows: First, methanol and ZSM-5 are mixed to obtain a mixture, wherein the mass ratio of methanol to ZSM-5 molecular sieve is 30:1, and the mass ratio of stainless steel grinding balls to methanol is 10:1, and then the mixture is added into the ball milling tank of the planetary ball mill at one time, and the reaction product is obtained by ball milling for 6 hours under vacuum conditions, the reaction temperature is room temperature, and the ball milling rate is 600 r / min. After the reaction is completed, the gas generated by the reaction is collected with a gas collecting bag, and finally the reaction mixture is taken out, rotary evaporated, and the liquid phase is collected for recycling.
[0017] The collected gas was detected by GCMS ( Figure 2 ), the results showed that its main components were ethylene and methanol.
[0018] The collected gas is passed into a bromine carbon tetrachloride solution and an acidic potassium permanganate solution ( Figure 3 ), it can be observed that the collected gas decolorizes both solutions.
[0019] The collected liquid phase was detected by GC ( Figure 4 ), the results showed that its component was methanol.
[0020] In summary, methanol and ZSM-5 were successfully used to prepare light olefins under the conditions of a mass ratio of methanol to ZSM-5 molecular sieve of 30:1, a mass ratio of stainless steel grinding balls to methanol of 10:1, a ball mill speed of 600 r / min, and a reaction time of 6 h.
[0021] Example 2 This embodiment provides a method for preparing light olefins using methanol, ZSM-5, and SAPO-34 molecular sieves under mechanochemical conditions. The schematic diagram of the preparation process is shown in Figure 1 The detailed preparation steps are as follows: First, methanol, ZSM-5 and SAPO-34 are mixed to obtain a mixture, wherein the mass ratio of methanol to the mixed molecular sieve is 10:1, and the mass ratio of stainless steel grinding balls to methanol is 15:1; then the mixture is added into the ball milling tank of a planetary ball mill at one time, and the reaction product is obtained by ball milling for 7 h under vacuum conditions, the reaction temperature is room temperature, and the ball milling rate is 600 r / min; then, after the reaction is completed, the gas generated by the reaction is collected with a gas collecting bag, and finally the reaction mixture is taken out, rotary evaporated, and the liquid phase is collected for recycling.
[0022] The collected gas was detected by GCMS ( Figure 5 ), the results showed that its main components were ethylene and methanol.
[0023] The collected gas was passed into a bromine tetrachloride solution and an acidic potassium permanganate solution (same as in Example 1), and it was observed that the collected gas caused the two solutions to decolorize.
[0024] The collected liquid phase was detected by GC ( Figure 6 ), the results showed that its component was methanol.
[0025] In summary, light olefins were successfully prepared from methanol, ZSM-5 and SAPO-34 under the conditions of a mass ratio of methanol to mixed molecular sieve of 10:1, a mass ratio of stainless steel grinding balls to methanol of 15:1, a ball mill speed of 600 r / min and a reaction time of 7 h.
[0026] Example 3 This embodiment provides a method for preparing light olefins using methanol and ZSM-5 molecular sieve under mechanochemical conditions. The schematic diagram of the preparation process is shown in Figure 1 The detailed preparation steps are as follows: First, methanol and ZSM-5 are mixed to obtain a mixture, wherein the mass ratio of methanol to ZSM-5 molecular sieve is 15:1, and the mass ratio of stainless steel grinding balls to methanol is 20:1, and then the mixture is added into the ball milling tank of the planetary ball mill at one time, and the reaction product is obtained by ball milling for 7 hours under vacuum conditions, the reaction temperature is room temperature, and the ball milling rate is 400 r / min. After the reaction is completed, the gas generated by the reaction is collected with a gas collecting bag, and finally the reaction mixture is taken out, rotary evaporated, and the liquid phase is collected for recycling.
[0027] The collected gas was tested by GCMS (same as in Example 1), and the results showed that the main components were ethylene and methanol.
[0028] The collected gas was passed into a bromine tetrachloride solution and an acidic potassium permanganate solution (same as in Example 1), and it was observed that the collected gas caused the two solutions to decolorize.
[0029] The collected liquid phase was detected by GC ( Figure 7 ), the results showed that its component was methanol.
[0030] In summary, methanol and ZSM-5 were successfully used to prepare light olefins under the conditions of a mass ratio of methanol to ZSM-5 molecular sieve of 15:1, a mass ratio of stainless steel grinding balls to methanol of 20:1, a ball mill speed of 400 r / min, and a reaction time of 7 h.
[0031] Example 4 This embodiment provides a method for preparing light olefins using methanol and ZSM-5 molecular sieve under mechanochemical conditions. The schematic diagram of the preparation process is shown in Figure 1 The detailed preparation steps are as follows: First, methanol and ZSM-5 are mixed to obtain a mixture, wherein the mass ratio of methanol to ZSM-5 molecular sieve is 10:1, and the mass ratio of stainless steel grinding balls to methanol is 10:1, and then the mixture is added to the ball milling tank of the stirring ball mill for multiple times, and the reaction product is obtained by ball milling for 1 h under vacuum conditions, the reaction temperature is room temperature, and the ball milling rate is 500 r / min. After the reaction is completed, the gas generated by the reaction is collected with a gas collecting bag, and finally the reaction mixture is taken out, rotary evaporated, and the liquid phase is collected for recycling.
[0032] The collected gas was tested by GCMS (same as in Example 1), and the results showed that the main components were ethylene and methanol.
[0033] The collected gas was passed into a bromine tetrachloride solution and an acidic potassium permanganate solution (same as in Example 1), and it was observed that the collected gas caused the two solutions to decolorize.
[0034] The collected liquid phase was detected by GC (same as in Example 1), and the result showed that its component was methanol.
[0035] In summary, methanol and ZSM-5 were successfully used to prepare light olefins under the conditions of a mass ratio of methanol to ZSM-5 molecular sieve of 10:1, a mass ratio of stainless steel grinding balls to methanol of 10:1, a ball mill speed of 500 r / min, and a reaction time of 1 h.
[0036] Example 5 This embodiment provides a method for preparing light olefins using methanol and SAPO-34 molecular sieve under mechanochemical conditions. The schematic diagram of the preparation process is shown in Figure 1 The detailed preparation steps are as follows: First, methanol and SAPO-34 are mixed to obtain a mixture, wherein the mass ratio of methanol to SAPO-34 molecular sieve is 30:1, and the mass ratio of stainless steel grinding balls to methanol is 10:1, and then the mixture is added into the ball milling tank of a planetary ball mill at once, and the reaction product is obtained by ball milling for 6 hours under vacuum conditions, the reaction temperature is room temperature, and the ball milling rate is 600 r / min. After the reaction is completed, the gas generated by the reaction is collected with a gas collecting bag, and finally the reaction mixture is taken out, rotary evaporated, and the liquid phase is collected for recycling.
[0037] The collected gas was detected by GCMS ( Figure 8 ), the results showed that its main components were ethylene and methanol.
[0038] The collected gas is passed into a bromine carbon tetrachloride solution and an acidic potassium permanganate solution ( Fig. 9 ), it can be observed that the collected gas decolorizes both solutions.
[0039] The collected liquid phase was detected by GC ( Fig.10 ), the results showed that its component was methanol.
[0040] In summary, methanol and SAPO-34 were successfully used to prepare light olefins under the conditions of a mass ratio of methanol to SAPO-34 molecular sieve of 30:1, a mass ratio of stainless steel grinding balls to methanol of 10:1, a ball mill speed of 600 r / min, and a reaction time of 6 h.
[0041] Example 6 This embodiment provides a method for preparing light olefins using methanol and SAPO-18 molecular sieve under mechanochemical conditions. The schematic diagram of the preparation process is shown in Figure 1 The detailed preparation steps are as follows: First, methanol and SAPO-18 are mixed to obtain a mixture, wherein the mass ratio of methanol to SAPO-18 molecular sieve is 10:1, and the mass ratio of stainless steel grinding balls to methanol is 30:1; then the mixture is added into the ball milling tank of a stirring ball mill multiple times, and the reaction product is obtained by ball milling for 6 hours under vacuum conditions, the reaction temperature is room temperature, and the ball milling rate is 500 r / min; then, after the reaction is completed, the gas generated by the reaction is collected with a gas collecting bag, and finally the reaction mixture is taken out, rotary evaporated, and the liquid phase is collected for recycling.
[0042] The collected gas was tested by GCMS (same as in Example 5), and the results showed that the main components were ethylene and methanol.
[0043] The collected gas was passed into a bromine tetrachloride solution and an acidic potassium permanganate solution (same as in Example 5), and it was observed that the collected gas decolorized both solutions.
[0044] The collected liquid phase was detected by GC (same as in Example 5), and the result showed that its component was methanol.
[0045] In summary, methanol and SAPO-18 were successfully used to prepare light olefins under the conditions of a mass ratio of methanol to SAPO-18 molecular sieve of 10:1, a mass ratio of stainless steel grinding balls to methanol of 30:1, a ball mill speed of 500 r / min, and a reaction time of 6 h.
[0046] The above specific implementation method part specifically introduces the analytical method involved in the present invention. It should be noted that the above introduction is only to help those skilled in the art better understand the method and ideas of the present invention, rather than limiting the relevant content. Without departing from the principle of the present invention, those skilled in the art may also make appropriate adjustments or modifications to the present invention, and the above adjustments and modifications shall also fall within the scope of protection of the present invention.
Claims
1. A method for preparing light olefins using methanol and molecular sieves under mechanochemical conditions, characterized in that: The following steps are involved: (1) Mixing methanol and molecular sieve to obtain a mixture, then adding the mixture into a ball milling tank of a ball mill once or multiple times, and subjecting the mixture to ball milling reaction for 1 to 7 hours under vacuum conditions to obtain a reaction product; (2) After the reaction is completed, light olefin gas is obtained in the gas phase through separation.
2. The method for preparing light olefins by using methanol and molecular sieves under mechanochemical conditions according to claim 1, characterized in that: The ball mill includes but is not limited to a vibrating ball mill, a stirring ball mill, a drum ball mill and a planetary ball mill.
3. The method for preparing light olefins by using methanol and molecular sieves under mechanochemical conditions according to claim 1, characterized in that: The molecular sieve is a combination of one or more of ZSM-5, SAPO-34, MCM-41, and SAPO-11 in any proportion.
4. The method for preparing light olefins by using methanol and molecular sieves under mechanochemical conditions according to claim 1, characterized in that: The mass ratio of the molecular sieve to methanol is 0.1 to 3:
30.
5. The method for preparing light olefins by using methanol and molecular sieves under mechanochemical conditions according to claim 1, characterized in that: The mass ratio of the stainless steel grinding balls to methanol is 1-100:
1.
6. The method for preparing light olefins by using methanol and molecular sieves under mechanochemical conditions according to claim 1, characterized in that: The reaction temperature is room temperature, and the ball milling rate is 100-700 r / min.