A photocatalytic dehydrogenation device and method for methylcyclohexane

Abstract

This application discloses a photocatalytic dehydrogenation device and method for methylcyclohexane, comprising a gasifier, a heating reaction device, a chromatograph, and a product collector connected in sequence. The gasifier has a hydrogen inlet and a methylcyclohexane inlet. A xenon lamp light source is installed at a corresponding position in the heating reaction device. This device can dehydrogenate methylcyclohexane without external heating, achieving a hydrogen release process under mild conditions. The photocatalytic methylcyclohexane dehydrogenation has a fast start-up speed, on the order of seconds, significantly faster than the tens of minutes required for traditional thermal catalysis. Furthermore, the photocatalytic device of this application uses a fixed-bed reactor, enabling continuous feeding of methylcyclohexane and thus continuous hydrogen release. In addition, the device is equipped with a heating furnace, which provides additional heat for the photocatalytic reaction, further increasing the methylcyclohexane dehydrogenation rate and accelerating the hydrogen release speed.

Description

Technical Field

[0001] This application relates to a photocatalytic methylcyclohexane dehydrogenation device and method, belonging to the field of hydrogen energy storage and utilization. Background Technology

[0002] Hydrogen energy is widely considered one of the ultimate energy sources of the future; however, the storage and transportation of hydrogen has always been a bottleneck hindering its large-scale application. Among various hydrogen storage materials, organic liquid hydrogen storage materials have a high hydrogen storage capacity and can utilize existing oil and gas equipment for large-scale, long-distance hydrogen transportation, offering significant cost advantages. Methylcyclohexane is one of the most researched and widely used organic liquid hydrogen storage materials. It has been applied by internationally renowned companies for large-scale hydrogen transportation. For example, Chiyoda Corporation in Japan uses toluene to hydrogenate into methylcyclohexane, stores hydrogen in methylcyclohexane, transports it by sea to Japan, and finally releases the hydrogen by dehydrogenating the methylcyclohexane.

[0003] However, the dehydrogenation temperature of methylcyclohexane is relatively high, typically above 300°C. The catalyst is prone to deactivation at high temperatures, and the energy consumption for dehydrogenation is also high. In some applications requiring rapid hydrogen production, traditional thermocatalysis requires a lengthy heating process, making it difficult to meet the demand for rapid hydrogen production. Photocatalytic methylcyclohexane dehydrogenation can alleviate or even overcome these problems, enabling rapid start-up of methylcyclohexane dehydrogenation and achieving dehydrogenation under mild conditions. However, existing photocatalytic organic liquid dehydrogenation devices are usually intermittent batch reactors, unable to achieve continuous hydrogen release, which is detrimental to their scale-up applications.

[0004] In summary, the following problems need to be overcome to achieve hydrogen release from methylcyclohexane via dehydrogenation: 1) The dehydrogenation temperature is relatively high, and hydrogen release from methylcyclohexane must be achieved under relatively mild conditions; 2) The dehydrogenation reaction of methylcyclohexane has a slow start-up, and rapid start-up of the dehydrogenation reaction of methylcyclohexane must be achieved; 3) Photocatalytic methylcyclohexane dehydrogenation reactors are currently mainly intermittent, and their efficiency needs to be increased to achieve a continuous and rapid hydrogen release process. Summary of the Invention

[0005] According to one aspect of this application, a photocatalytic methylcyclohexane dehydrogenation apparatus is provided, comprising a gasifier, a heating reaction apparatus, a chromatograph, and a product collector connected in sequence.

[0006] The gasifier is equipped with a hydrogen inlet and a methylcyclohexane inlet.

[0007] Hydrogen gas is introduced into the gasification furnace through the hydrogen inlet via a pipe equipped with a gas flow rate controller;

[0008] Methylcyclohexane is fed into the gasifier through a pipeline equipped with a high-pressure constant flow pump via the methylcyclohexane inlet;

[0009] A xenon lamp light source is installed at a corresponding position in the heating reaction device.

[0010] Optionally, the heating reaction apparatus includes a heating furnace and a fixed-bed reactor disposed within the heating furnace;

[0011] The heating furnace is provided with a window, through which the light emitted by the xenon lamp light source shines on the catalyst surface.

[0012] Optionally, the middle part of the fixed-bed reactor is flattened to a thickness of 2-5 mm for loading catalyst.

[0013] Optionally, a thermocouple is fixed on the fixed-bed reactor.

[0014] Optionally, the fixed-bed reactor is made of quartz tube with a length of 10-20cm, a diameter of 6-12mm, and a visible light transmittance of ≥90%.

[0015] Optionally, the window is made of quartz light-transmitting glass with a thickness of 3-5mm, a diameter of 5-10cm, and a visible light transmittance of ≥90%.

[0016] According to another aspect of this application, a method for dehydrogenation based on the above-described dehydrogenation apparatus is also provided, comprising the following steps:

[0017] S1: Methylcyclohexane is fed into the gasifier via a high-pressure constant flow pump for gasification;

[0018] S2: The flow rate of the carrier hydrogen gas is adjusted by the gas flow rate controller to carry the vaporized methylcyclohexane into the heating reactor;

[0019] S3: Adjust the xenon lamp illumination intensity to regulate the dehydrogenation rate of methylcyclohexane;

[0020] S4: Check the chromatograph to monitor the conversion rate of methylcyclohexane to toluene;

[0021] S5: Collect the dehydrogenation product toluene from the product collector, while the generated hydrogen gas is discharged through a pipeline.

[0022] Optionally, the flow rate of methylcyclohexane in step S1 is 0.001-10 mL / min;

[0023] The temperature of the gasifier is 100-250℃.

[0024] Optionally, the flow rate of the carrier hydrogen gas in step S2 is 10-200 mL / min.

[0025] Optionally, in step S3, the illuminance of the xenon lamp is 1-4 W / cm². 2 .

[0026] The beneficial effects that this application can produce include:

[0027] The photocatalytic methylcyclohexane dehydrogenation device provided in this application can dehydrogenate methylcyclohexane without external heating, realizing the hydrogen release process of methylcyclohexane under mild conditions; the photocatalytic methylcyclohexane dehydrogenation has a fast start-up speed, with a start-up time in the second range, which is significantly faster than the start-up speed of traditional thermal catalysis which takes tens of minutes.

[0028] Furthermore, the photocatalytic device of this application uses a fixed-bed reactor, which enables continuous feeding of methylcyclohexane, thereby allowing the device to continuously release hydrogen. In addition, the device is equipped with a heating furnace, which can provide additional heat for the photocatalytic reaction, further increasing the dehydrogenation rate of methylcyclohexane and accelerating the hydrogen release speed of the device. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the photocatalytic methylcyclohexane dehydrogenation device provided in one embodiment of this application;

[0030] Figure 2 This is a schematic diagram of the heating furnace and reactor in a photocatalytic methylcyclohexane dehydrogenation device provided in one embodiment of this application;

[0031] Figure 3 This is a schematic diagram showing the relationship between the conversion rate of methylcyclohexane and light intensity in Example 3 of this application.

[0032] List of components and reference numerals:

[0033] 1. Gas flow rate controller; 2. High-pressure constant flow pump; 3. Gasification furnace; 4. Heating reaction device; 5. Xenon lamp light source; 6. Chromatograph; 7. Product collector; 8. Heating furnace; 9. Thermocouple; 10. Fixed bed reactor; 11. Window. Detailed Implementation

[0034] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0035] like Figure 1 As shown, according to one aspect of this application, a photocatalytic methylcyclohexane dehydrogenation apparatus is provided, comprising a gasifier 3, a heating reaction apparatus 4, a chromatograph 6, and a product collector 7 connected in sequence.

[0036] The gasifier 3 is provided with a hydrogen inlet and a methylcyclohexane inlet;

[0037] Hydrogen gas is introduced into the gasification furnace 3 through the hydrogen inlet via a pipe equipped with a gas flow rate controller 1;

[0038] Methylcyclohexane is fed into the gasifier 3 through a pipeline equipped with a high-pressure constant flow pump 2 via the methylcyclohexane inlet;

[0039] A xenon lamp light source 5 is provided at a corresponding position in the heating reaction device 4.

[0040] like Figure 2 As shown, the heating reaction device 4 includes a heating furnace 8 and a fixed-bed reactor 10 disposed within the heating furnace 8;

[0041] The heating furnace 8 is provided with a window 11, through which the light emitted by the xenon lamp light source 5 shines on the catalyst surface.

[0042] The fixed-bed reactor 10 is flattened in the middle, with a thickness of 2-5 mm, for loading the catalyst.

[0043] Thermocouples 9 are fixed on the fixed bed reactor 10.

[0044] The fixed-bed reactor 10 is made of quartz tube with a length of 10-20cm, a diameter of 6-12mm, and a visible light transmittance of ≥90%.

[0045] The window 11 is made of quartz light-transmitting window sheet with a thickness of 3-5mm, a diameter of 5-10cm, and a visible light transmittance of ≥90%.

[0046] According to another aspect of this application, a method for dehydrogenation based on the above-described dehydrogenation apparatus is also provided, comprising the following steps:

[0047] S1: Methylcyclohexane is fed into gasifier 3 via high-pressure constant flow pump 2 for gasification;

[0048] S2: The flow rate of the carrier hydrogen gas is adjusted by the gas flow rate controller 1 to carry the vaporized methylcyclohexane into the heating reactor;

[0049] S3: Adjust the xenon lamp illumination intensity to regulate the dehydrogenation rate of methylcyclohexane;

[0050] S4: View the chromatogram displayed on chromatograph 6 to monitor the conversion rate of methylcyclohexane to toluene;

[0051] S5: Collect the dehydrogenation product toluene from product collector 7, while the generated hydrogen gas is discharged through a pipeline.

[0052] The flow rate of methylcyclohexane in step S1 is 0.001-10 mL / min;

[0053] The temperature of gasifier 3 is 100-250℃.

[0054] The flow rate of the carrier hydrogen gas in step S2 is 10-200 mL / min.

[0055] In step S3, the illuminance of the xenon lamp is 1-4 W / cm². 2 .

[0056] The following are specific embodiments of the dehydrogenation of methylcyclohexane using the above-described apparatus and method:

[0057] Example 1

[0058] Methylcyclohexane is introduced into gasifier 3 via high-pressure constant flow pump 2 at a flow rate of 0.005 mL / min, and the temperature of gasifier 3 is 180 °C. Hydrogen is used as a carrier gas to carry methylcyclohexane from gasifier 3 into fixed-bed reactor 10 at a flow rate of 30 mL / min. Fixed-bed reactor 10 is packed with 80 mg of Pt / TiO2 catalyst at a temperature of 3.8 W / cm². 2 Under light intensity, methylcyclohexane undergoes a dehydrogenation reaction.

[0059] After the reaction proceeded for half an hour, the conversion rate of methylcyclohexane was detected by chromatograph 6 to be 99.9%.

[0060] After the xenon lamp light source 5 was turned off, the methylcyclohexane conversion rate was detected by the chromatograph 6 to have dropped to 0.

[0061] Example 2

[0062] Methylcyclohexane is introduced into gasifier 3 via high-pressure constant flow pump 2 at a flow rate of 0.01 mL / min, and the temperature of gasifier 3 is 180 °C. Hydrogen is used as a carrier gas to carry methylcyclohexane from gasifier 3 into fixed-bed reactor 10 at a flow rate of 30 mL / min. Fixed-bed reactor 10 is packed with 80 mg of Pt / Al₂O₃ catalyst at a temperature of 3.8 W / cm². 2 Under light intensity, methylcyclohexane undergoes a dehydrogenation reaction.

[0063] Thirty seconds after the xenon lamp light source 5 was turned on, the methylcyclohexane conversion rate was detected by the chromatograph 6 to be 62.6%.

[0064] After the xenon lamp light source 5 was turned off, the methylcyclohexane conversion rate was detected by the chromatograph 6 to have dropped to 0.

[0065] Example 3

[0066] Methylcyclohexane is introduced into gasifier 3 via high-pressure constant flow pump 2 at a flow rate of 0.01 mL / min. The temperature of gasifier 3 is 180℃. Hydrogen is used as a carrier gas to carry methylcyclohexane from gasifier 3 into fixed-bed reactor 10 at a flow rate of 30 mL / min. Fixed-bed reactor 10 contains 80 mg of Pt / TiO2 catalyst. Methylcyclohexane undergoes a dehydrogenation reaction under the irradiation of xenon lamp source 5, with the light intensity of xenon lamp source 5 varying from 2.0 to 3.4 W / cm². 2 The conversion rate of methylcyclohexane was detected by chromatograph 6.

[0067] The relationship between the conversion rate of methylcyclohexane and light intensity is as follows: Figure 3 As shown, the conversion rate of methylcyclohexane increases with increasing light intensity, gradually increasing from 5.4% to 99.9%.

[0068] Example 4

[0069] Methylcyclohexane is introduced into gasifier 3 via a high-pressure constant flow pump 2 at a flow rate of 0.01 mL / min. The temperature of gasifier 3 is 180 °C. Hydrogen is used as a carrier gas to carry methylcyclohexane from gasifier 3 into fixed-bed reactor 10 at a flow rate of 30 mL / min. Fixed-bed reactor 10 contains 80 mg of Pt / TiO2 catalyst. Methylcyclohexane undergoes a dehydrogenation reaction under xenon lamp irradiation (xenon lamp light source 5 with a light intensity of 2.0 W / cm²). 2 The conversion rate of methylcyclohexane was 5.4%, as determined by chromatograph 6.

[0070] The heating furnace 8 was then started, and the furnace temperature was maintained at 200°C. After half an hour, the conversion rate of methylcyclohexane was measured to have increased to 97.4%.

[0071] The above description is only a part of the embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A photocatalytic methylcyclohexane dehydrogenation device, characterized in that, It includes a gasifier, a heating reaction device, a chromatograph, and a product collector connected in sequence; The gasifier is equipped with a hydrogen inlet and a methylcyclohexane inlet. Hydrogen gas is introduced into the gasification furnace through the hydrogen inlet via a pipe equipped with a gas flow rate controller; Methylcyclohexane is fed into the gasifier through a pipeline equipped with a high-pressure constant flow pump via the methylcyclohexane inlet; A xenon lamp light source is installed at a corresponding position in the heating reaction device.

2. The photocatalytic methylcyclohexane dehydrogenation device according to claim 1, characterized in that, The heating reaction apparatus includes a heating furnace and a fixed-bed reactor disposed within the heating furnace; The heating furnace is provided with a window, through which the light emitted by the xenon lamp light source shines on the catalyst surface.

3. The photocatalytic methylcyclohexane dehydrogenation device according to claim 2, characterized in that, The fixed-bed reactor is flattened in the middle, with a thickness of 2-5 mm, for loading the catalyst.

4. The photocatalytic methylcyclohexane dehydrogenation device according to claim 3, characterized in that, Thermocouples are fixed on the fixed-bed reactor.

5. The photocatalytic methylcyclohexane dehydrogenation device according to claim 3, characterized in that, The fixed-bed reactor uses quartz tubes with a length of 10-20cm, a diameter of 6-12mm, and a visible light transmittance of ≥90%.

6. The photocatalytic methylcyclohexane dehydrogenation device according to claim 2, characterized in that, The window is made of quartz light-transmitting glass with a thickness of 3-5mm, a diameter of 5-10cm, and a visible light transmittance of ≥90%.

7. A method for dehydrogenation using a dehydrogenation apparatus according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Methylcyclohexane is fed into the gasifier via a high-pressure constant flow pump for gasification; S2: The flow rate of the carrier hydrogen gas is adjusted by the gas flow rate controller to carry the vaporized methylcyclohexane into the heating reactor; S3: Adjust the xenon lamp illumination intensity to regulate the dehydrogenation rate of methylcyclohexane; S4: Check the chromatograph to monitor the conversion rate of methylcyclohexane to toluene; S5: Collect the dehydrogenation product toluene from the product collector, while the generated hydrogen gas is discharged through a pipeline.

8. The photocatalytic methylcyclohexane dehydrogenation device according to claim 7, characterized in that, The flow rate of methylcyclohexane in step S1 is 0.001-10 mL / min; The temperature of the gasifier is 100-250℃.

9. The photocatalytic methylcyclohexane dehydrogenation device according to claim 7, characterized in that, The flow rate of the carrier hydrogen gas in step S2 is 10-200 mL / min.

10. The photocatalytic methylcyclohexane dehydrogenation device according to claim 7, characterized in that, In step S3, the illuminance of the xenon lamp is 1-4 W / cm². 2 .

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