Microchannel reactor and method for synthesizing carbonyl sulfide

Abstract

The invention belongs to the technical field of carbonyl sulfide synthesis, and particularly relates to a micro-channel reactor and method for synthesizing carbonyl sulfide, and the reactor comprises a hydrogen sulfide gas cylinder, a carbon monoxide gas cylinder, a gas mixer and a micro-channel reactor. And finally, reacting at the reaction temperature of 200-300 DEG C under the reaction pressure of normal pressure to 1 MPa to obtain carbonyl sulfide. Through the design of the preheating zone and the reaction zone, optimal fluid dynamics and heat transfer environments are respectively provided for the preparation stage and the reaction stage of the reaction, and the regulation and control of the reaction process are realized, so that the selectivity and the yield of carbonyl sulfide are improved, and the generation of byproducts is inhibited. In addition, due to the fact that the gas-solid contact efficiency is improved, the reaction time is shortened.

Description

Technical Field

[0001] This application belongs to the field of carbonyl sulfide synthesis technology, specifically relating to a microchannel reactor and method for synthesizing carbonyl sulfide. Background Technology

[0002] Carbonyl sulfide (COS), as the simplest sulfur-containing organic compound, is an indispensable basic raw material and intermediate in the chemical industry. Its applications are wide-ranging, not only serving as a key precursor in the synthesis of highly effective fungicides, herbicides, and plant growth regulators in the pesticide field, but also playing a vital role in pharmaceutical synthesis, materials science, and deep desulfurization processes for natural gas and syngas. Industrially, the mainstream synthetic route for COS involves the gas-phase catalytic reaction of hydrogen sulfide and carbon monoxide under high temperature and in the presence of a solid catalyst. For a long time, this reaction has primarily been carried out in traditional fixed-bed or fluidized-bed reactors. Although these technologies are mature and have achieved large-scale industrial production, their inherent physical limitations have led to a series of intractable technical bottlenecks, severely restricting further improvements in production efficiency, product selectivity, and economic benefits.

[0003] In traditional fixed-bed reactors, catalyst particles are typically packed in the bed at the millimeter or even centimeter scale. This macroscopic structure results in an extremely low gas-solid interface area, making the diffusion of gaseous reactant molecules to the catalyst active sites the rate-controlling step of the entire reaction. This diffusion limitation not only prolongs the reaction time required to reach the target conversion rate but also leads to uneven gas flow rate and concentration distribution within the reactor, thereby reducing reaction efficiency. Furthermore, the synthesis of COS is an exothermic process; in a bed of packed catalyst particles, heat transfer efficiency is low, easily leading to the formation of localized hot spots within the bed. Localized overheating not only exacerbates catalyst sintering and deactivation but also triggers a series of side reactions. In high-temperature regions, H2S may react with CO to produce carbon disulfide and carbon dioxide, or CO may undergo disproportionation. These side reactions not only reduce the selectivity of the target product COS but also increase the cost and difficulty of subsequent separation and purification.

[0004] The technical solution disclosed in CN110862087A is a method for preparing industrial carbonyl sulfide. This technology uses a mixture of toluene, 2-mercapto-6-chlorobenzoxazole, and DMF as raw materials, reacts them under liquid-phase conditions, and obtains COS products through compression and single-stage distillation. Its process parameters include a reaction temperature of 80-120℃, a pressure of 0.5-2.0 MPa, and a raw material molar ratio of 1:1-1:3. Although this patent provides a specific synthetic route, it relies on a liquid-phase reaction system, has high raw material costs, and is complex to operate, making it unsuitable for direct application to the gas-phase catalytic process of H2S and CO. Furthermore, this method requires an additional distillation step, resulting in high energy consumption, and the byproduct formation rate exceeds 10%, with a selectivity of less than 90%. Compared to the target gas-phase synthesis process in this application, it has significant shortcomings in both efficiency and economy.

[0005] In recent years, microchannel reactor technology has provided a solution for enhancing heterogeneous catalytic reactions due to its unique scale effect. Microchannel reactors possess a large specific surface area. This structure shortens the diffusion distance from the millimeter level to the micrometer level, enhancing the mass transfer process and shifting the reaction rate from the diffusion-controlled region to the intrinsic kinetic control region, thus achieving high conversion rates within extremely short residence times. Simultaneously, its excellent heat transfer performance allows for rapid removal of reaction heat, achieving near-isothermal reaction conditions and fundamentally suppressing side reactions and catalyst sintering caused by localized overheating.

[0006] In summary, current technologies fail to provide an efficient gas-phase H2S and CO synthesis scheme with minimal side reactions. Traditional fixed-bed and fluidized-bed processes are limited by reactor structure, resulting in drawbacks such as small specific surface area, long residence time, and imprecise temperature control, leading to low COS yield, high byproduct rate, and short catalyst lifetime. Therefore, developing a novel carbonyl sulfide preparation process to improve synthesis efficiency is an urgent problem to be solved. Summary of the Invention

[0007] To address the fact that existing technologies fail to provide efficient gas-phase H2S and CO synthesis methods with low side reactions, this application proposes a microchannel reactor and method for synthesizing carbonyl sulfide. The technical solution of this application is as follows: On the one hand, this application provides a microchannel reactor for synthesizing carbonyl sulfide, including a hydrogen sulfide cylinder, a carbon monoxide cylinder, a gas mixer, and a microchannel reactor; The outlets of the hydrogen sulfide cylinder and the carbon monoxide cylinder are connected to the inlet of the gas mixer, and the outlet of the gas mixer is connected to the microchannel reactor. The microchannel reactor is equipped with a gas preheating channel, a gas reaction channel, a gas distributor, and a mixed gas outflow pipe. The gas preheating channel has its inlet end connected to the gas mixer's outlet end, and the gas preheating channel's outlet end is connected to the gas distributor's inlet end. The inlet end of the gas reaction channel is connected to the outlet end of one of the gas distributors, and the outlet ends of the gas reaction channel are all connected to the mixed gas outlet pipe.

[0008] Preferably, the number of gas distributors is no less than two, which is equal to the number of gas reaction channels.

[0009] Preferably, the gas preheating channel has a continuous curved channel structure; the diameter of the gas preheating channel is 1000~1500μm, and the ratio of the bending radius of the gas preheating channel to the channel diameter R / D>5.

[0010] Preferably, the gas reaction channel is a continuous serpentine channel structure, and the inner diameter of the gas reaction channel is 100~500μm; the ratio of the bending radius of the gas reaction channel to the channel diameter R / D < 2.

[0011] Preferably, the gas reaction channel is made of Hastelloy or 316L stainless steel with a silicon dioxide coating.

[0012] Preferably, the inner wall of the gas reaction channel is coated with a 10-50 nm thick nanoscale catalyst molybdenum sulfide, or the gas reaction channel is filled with activated carbon-supported metal sulfide particles with a particle size of 50-90 μm as a catalyst.

[0013] On the other hand, this application provides a method for synthesizing carbonyl sulfide, the method comprising the following steps: Step S1. The hydrogen sulfide gas from the hydrogen sulfide cylinder and the carbon monoxide gas from the carbon monoxide cylinder are introduced into the gas mixer at a volume ratio of 1:1 to 1:2 to complete the premixing. Step S2. Introduce the premixed gas into the gas preheating channel of the microchannel reactor and preheat it to 100~150℃; Step S3. The gas passing through the gas preheating channel is connected to each gas reaction channel through the gas distributor; Step S4. Control the reaction temperature of the microchannel reactor to 200~300℃, the total gas velocity of the mixed gas to 10~50 mL / min, and the reaction pressure to atmospheric pressure to 1 MPa, so that the gas reacts in the gas reaction channel; Step S5. The reaction products are collected through a mixed gas outlet pipe to obtain carbonyl sulfide.

[0014] Preferably, in step S4, the residence time of the gas in the gas reaction channel is 10~60s.

[0015] Preferably, in step S5, the yield of carbonyl sulfide is greater than 95%.

[0016] In summary, the microchannel reactor device of this application has the following advantages compared with traditional reactors or other microreactors with uniform structures: This application provides an optimized fluid dynamics and heat transfer environment for the preheating and reaction stages of the reaction through the design of the preheating and reaction zones, respectively, thereby enabling the control of the reaction process, improving the selectivity and yield of carbonyl sulfide, and suppressing the formation of by-products.

[0017] The device's extremely small internal gas holdup and ultra-high heat transfer efficiency fundamentally eliminate the risk of thermal runaway. The internal multi-stage micro-reaction channel structure ensures extremely high mass and heat transfer efficiency and reaction rate. By selecting Hastelloy or employing functionalized coating technology, this application enables the device to operate stably for extended periods in harsh, corrosive environments containing high temperatures and sulfur, ensuring the continuity and economy of industrial production.

[0018] This application offers extremely high reaction selectivity, reduces raw material waste, and its efficient energy utilization and compact equipment size significantly reduce plant footprint and operating energy consumption, meeting the requirements of green chemistry and sustainable development. Furthermore, this application shortens reaction time by improving the efficiency of gas-solid contact. Attached Figure Description

[0019] Appendix Figure 1 This is a structural diagram of the microchannel reactor used in the synthesis of carbonyl sulfide according to this application.

[0020] Explanation of the symbols in the attached diagram: 1. Hydrogen sulfide cylinder; 2. Carbon monoxide cylinder; 3. Gas mixture; 4. Microchannel reactor; 401. Gas preheating channel; 402. Gas reaction channel; 403. First distributor; 404. Second distributor; 405. Third distributor; 406. Mixed gas outflow pipe. Detailed Implementation

[0021] To further illustrate the technical means and effects adopted by this application in order to achieve the intended purpose of the invention, the following detailed description of the specific implementation methods, structures, features and effects of this application is provided in conjunction with the accompanying drawings and preferred embodiments.

[0022] Device Examples See Figure 1 The microchannel reactor for synthesizing carbonyl sulfide disclosed in this embodiment is a continuous device integrating gas supply, premixing, reaction, and product extraction. Hydrogen sulfide cylinder 1, as the gas source of hydrogen sulfide, one of the reactants, is usually equipped with a pressure reducing valve and a pressure gauge to control the output pressure.

[0023] Carbon monoxide cylinder 2, serving as the gas source for another reactant, carbon monoxide, is also equipped with a pressure reducing valve and a pressure gauge.

[0024] Gas mixer 3 is connected to the outlet of hydrogen sulfide cylinder 1 and carbon monoxide cylinder 2, and is used to fully premix the two reactant gases before they enter the main body of the reactor.

[0025] The microchannel reactor 4 integrates multiple functions such as gas preheating, distribution, catalytic reaction and product collection.

[0026] The outlets of hydrogen sulfide cylinder 1 and carbon monoxide cylinder 2 are connected to the inlet of gas mixer 3 via their respective pipelines. To control and proportionally adjust the flow rates of the two gases, a mass flow controller can be installed on each pipeline. The outlet of gas mixer 3 is connected to the inlet of microchannel reactor 4.

[0027] The microchannel reactor 4 has an internal structure that can be divided into four regions: a gas preheating channel 401, a gas distributor 403, a parallel gas reaction channel 402, and a mixed gas outflow pipe 404.

[0028] The gas preheating channel 401 features a gentle serpentine structure for mild preheating and homogenization, with its diameter controlled within the range of 1000-1500 μm. The ratio of the bending radius to the channel diameter, R / D, is greater than 5. Compared to straight channels that rely solely on heat conduction, the curved channel allows heat transferred from the outside of the reactor to the gas flow core more quickly and evenly, ensuring that all gas molecules reach the set preheating temperature of 100-150°C before entering the catalytic reaction zone. This avoids overheating or underheating of some gases due to uneven preheating. Although H2S and CO gases have been premixed in the upstream mixer 3, slight concentration inhomogeneities may still exist in laminar flow after entering the microchannel, which can be several meters or tens of meters long. The gas preheating channel 401 further homogenizes the gas components. During the preheating stage, before the optimal reaction temperature of 200-300°C is reached, sufficient heat exchange and mixing are ensured while avoiding violent fluid shearing and collisions, thereby effectively suppressing possible side reactions and improving the purity of the final product.

[0029] The preheated gas flows out of the preheating channel 401 and enters the gas distributor 403. The reactor is equipped with at least two gas distributors and a corresponding number of gas reaction channels. The distributors uniformly distribute the single feed stream to the downstream microchannel reaction units.

[0030] The gas reaction channel 402 is a continuous serpentine channel structure with an inner diameter controlled between 100 and 500 μm. With an R / D ratio < 2, it breaks the inherent laminar flow state within the microchannel, allowing H2S and CO molecules to rapidly and randomly tumble and mix across the channel cross-section. This significantly increases the collision frequency between reactant molecules and the catalyst active sites coated on the channel inner wall, overcoming the diffusion limitations common in traditional reactors and thus improving the intrinsic reaction rate. The 100-500 μm channel diameter increases the reactor's specific surface area. For exothermic reactions like carbonyl sulfide synthesis, the heat generated can be rapidly transferred to the channel wall over a very short distance and removed by an external temperature control system. This design fundamentally eliminates the risk of temperature runaway, escalated side reactions, or even explosions caused by heat accumulation, achieving inherent safety in the reaction process. Due to the greatly improved mass and heat transfer efficiency, the chemical reaction can be completed in a very short time, and the short residence time also helps to inhibit further decomposition or transformation of products, improving reaction selectivity.

[0031] The reaction medium contains corrosive gas H2S at high temperature. The materials for the gas reaction channel 402 and the preheating channel 401 can be Hastelloy or 316L stainless steel with a silicon dioxide coating.

[0032] The reaction products are collected from the outlets of all parallel gas reaction channels 402 and guided to the outside of the reactor, entering the downstream cooling, separation and analysis unit.

[0033] Implementation principle of the device: Step S1: Reaction gas supply and premixing Open the valves of hydrogen sulfide cylinder 1 and carbon monoxide cylinder 2, maintaining the volume ratio of hydrogen sulfide to carbon monoxide between 1:1 and 1:2. The mixture then enters gas mixer 3. The mixer can be a simple T-connector to ensure uniform mixing of the two gases before they enter the reactor body.

[0034] Step S2: Gas preheating Start the temperature control system of microchannel reactor 4. Set and stabilize the temperature of the heating zone at 100~150℃. The H2S / CO mixed gas flowing out of mixer 3 enters microchannel reactor 4 and first flows through gas preheating channel 401. In this region, the gas flows in the channel and exchanges heat efficiently with the channel wall, and its temperature is rapidly and uniformly raised to the set preheating temperature.

[0035] Step S3: Gas Distribution The preheated gas, with a controlled flow rate of 10-50 mL / min, flows into the gas distributor 403, setting and stabilizing the temperature of the heating zone corresponding to the gas reaction channel 402 at 200-300℃. The pressure of the entire reaction system is maintained between atmospheric pressure and 1 MPa. The preheated gas entering the reaction channel 402 undergoes a rapid exothermic reaction under the influence of high temperature and catalyst, with a residence time in the reaction channel 402 of less than 1 minute. Step S5: Product Collection and Analysis The gas mixture after the reaction is collected from the outlet of each reaction channel 402 to the mixed gas outlet pipe 404.

[0036] Examples 1-4 and Comparative Examples 1-3 are based on the apparatus provided in the apparatus embodiments. However, it should be noted that due to the cost of custom-made apparatus, the diameter of the preheating channel 401 is controlled within the range of 1300 μm, the ratio of the bending radius to the channel diameter (R / D) is 6, and the inner diameter of the gas reaction channel 402 is controlled at 300 μm with an R / D of 1.5. However, the technical effects defined in this application can be achieved within the parameters specified in this application.

[0037] Example 1 The carbon monoxide gas was controlled at a volume ratio of 1:1, the preheating temperature was 120℃, the reaction temperature was 250℃, the total gas velocity of the mixed gas was 30 mL / min, the reaction pressure was atmospheric pressure, the channel material was Hastelloy, the catalyst was a wall-supported MoS2 catalyst with a thickness of 20 nm, and the reaction residence time was 1 min.

[0038] After testing, the COS yield was 98.2%, the byproduct CS2 was less than 2%, and the catalyst showed no activity decay after 100 hours of continuous operation.

[0039] Example 2 The carbon monoxide gas was controlled at a volume ratio of 1:1.5, the preheating temperature was 100℃, the reaction temperature was 280℃, the total gas velocity of the mixed gas was 50 mL / min, the reaction pressure was 0.5 MPa, the channel material was Hastelloy, and the catalyst was activated carbon-supported WS2 particles with a particle size of 50~90μm, with a loading of 8%. The reaction residence time was 50s.

[0040] After testing, the COS yield was 97.5%, and the catalyst showed no activity decay after 100 hours of continuous operation.

[0041] Example 3 The carbon monoxide gas was controlled at a volume ratio of 1:1, the preheating temperature was 100℃, the reaction temperature was 300℃, the total gas velocity of the mixed gas was 30 mL / min, the reaction pressure was 1 MPa, the channel material was Hastelloy, and the catalyst was a wall-supported MoS2 catalyst with a thickness of 10 nm. The reaction residence time was 10 s.

[0042] After testing, the COS yield was 95.8%, and the catalyst showed no activity decay after 100 hours of continuous operation.

[0043] Example 4 The carbon monoxide gas volume ratio was controlled at 1:2, the preheating temperature was 150℃, the reaction temperature was 200℃, the total gas velocity of the mixed gas was 10 mL / min, the reaction pressure was atmospheric pressure, the channel material was Hastelloy, and the catalyst was a wall-supported MoS2 catalyst with a thickness of 50 nm. The reaction residence time was 55 s.

[0044] After testing, the COS yield was 96.9%, and the catalyst showed no activity decay after 100 hours of continuous operation.

[0045] Comparative Example 1 The difference between this comparative example and Example 1 is that this comparative example was not preheated, and the COS yield was 86.4% after testing.

[0046] Comparative Example 2 The difference between this comparative example and Example 1 is that the reaction temperature of this comparative example is 400°C, and the COS yield was tested to be 79.1%.

[0047] Comparative Example 3 The difference between this comparative example and Example 1 is that the reaction residence time in this comparative example is 5 minutes, and the COS yield was 71.3% after testing.

[0048] Comparative Example 4 The difference between this comparative example and Example 1 is that the gas reaction channel in this comparative example is changed to a straight line. After testing, the COS yield is 74.6%.

[0049] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A microchannel reactor for synthesizing carbonyl sulfide, characterized in that, It includes a hydrogen sulfide cylinder (1), a carbon monoxide cylinder (2), a gas mixer (3), and a microchannel reactor (4). The outlets of the hydrogen sulfide cylinder (1) and the carbon monoxide cylinder (2) are connected to the inlet of the gas mixer (3), and the outlet of the gas mixer (3) is connected to the microchannel reactor (4). The microchannel reactor (4) is provided with a gas preheating channel (401), a gas reaction channel (402), a gas distributor (403), and a mixed gas outflow pipe (404). The gas preheating channel (401) is connected to the gas outlet of the gas mixer (3), and the gas outlet of the gas preheating channel (401) is connected to the gas inlet of the gas distributor (403). The inlet of the gas reaction channel (402) is connected to the outlet of one of the gas distributors (403), and the outlet of the gas reaction channel (402) is connected to the mixed gas outlet pipe (404).

2. The microchannel reactor for synthesizing carbonyl sulfide according to claim 1, characterized in that, The number of gas distributors (403) is equal to the number of gas reaction channels (402) and is not less than 2.

3. The microchannel reactor for synthesizing carbonyl sulfide according to claim 1, characterized in that, The gas preheating channel (401) is a continuous curved channel structure. The diameter of the gas preheating channel (401) is 1000~1500μm, and the ratio of the bending radius to the channel diameter of the gas preheating channel (401) is R / D>5.

4. The microchannel reactor for synthesizing carbonyl sulfide according to claim 1, characterized in that, The gas reaction channel (402) is a continuous channel structure with an inner diameter of 100~500μm and a bending radius to channel diameter ratio R / D < 2.

5. The microchannel reactor for synthesizing carbonyl sulfide according to claim 1, characterized in that, The gas reaction channel (402) is made of Hastelloy or 316L stainless steel with a silicon dioxide coating.

6. The microchannel reactor for synthesizing carbonyl sulfide according to claim 1, characterized in that, The inner wall of the gas reaction channel (402) is coated with molybdenum sulfide nanocatalyst with a thickness of 10~50 nm, or the gas reaction channel (402) is filled with activated carbon-supported metal sulfide particles with a particle size of 50~90 μm as catalyst.

7. A method for synthesizing carbonyl sulfide, characterized in that, Based on the microchannel reactor for synthesizing carbonyl sulfide according to any one of claims 1 to 6, the method includes the following steps: Step S1. The hydrogen sulfide gas output from the hydrogen sulfide cylinder (1) and the carbon monoxide gas output from the carbon monoxide cylinder (2) are introduced into the gas mixer (3) at a volume ratio of 1:1 to 1:2 to complete the premixing; Step S2. Introduce the premixed gas into the gas preheating channel (401) of the microchannel reactor (4) and preheat it to 100~150℃; Step S3. The gas passing through the gas preheating channel (401) is connected to each gas reaction channel (402) through the gas distributor (403). Step S4. Control the reaction temperature of the microchannel reactor (4) to 200~300℃, the total gas velocity of the mixed gas to 10~50mL / min, and the reaction pressure to atmospheric pressure to 1 MPa, so that the gas reacts in the gas reaction channel (402); Step S5. The reaction products are collected through the mixed gas outlet pipe (404) to obtain carbonyl sulfide.

8. The method for synthesizing carbonyl sulfide according to claim 7, characterized in that, In step S4, the residence time of the gas in the gas reaction channel (402) is 10~60s.

9. The method for synthesizing carbonyl sulfide according to claim 7, characterized in that, In step S5, the yield of carbonyl sulfide is greater than 95%.

Images