A carbazole-based hydrogen storage carrier resistant to component drift and its application method

Abstract

This invention provides a carbazole-based hydrogen storage carrier resistant to component drift and its method of use. The hydrogen storage carrier comprises: a carbazole-based hydrogen storage component, including: N-ethylcarbazole, incompletely hydrogenated carbazole homologues, and fully hydrogenated carbazole homologues; C10-C18 straight-chain or branched-chain alkanes; and polyvinylpyrrolidone. During the hydrogenation-dehydrogenation cycle of the hydrogen storage carrier, the proportion of the incompletely hydrogenated carbazole homologues in the total mass of the carbazole-based hydrogen storage component is maintained within a window of 5% to 35%. By maintaining the proportion of the incompletely hydrogenated carbazole homologues within a eutectic window of 5% to 35%, this invention can significantly suppress fluctuations in the physical properties of the carbazole-based hydrogen storage carrier caused by changes in the hydrogen storage state during cyclic operation.

Description

Technical Field

[0001] This invention belongs to the field of liquid organic hydrogen storage technology, specifically relating to a carbazole-based hydrogen storage carrier resistant to component drift and its application method. Background Technology

[0002] Hydrogen energy is considered an ideal energy carrier for the future due to its advantages such as abundant resources, no pollution, renewability, and high energy density. The storage and transportation of hydrogen are key aspects for realizing the large-scale application of hydrogen energy.

[0003] Currently, commonly used hydrogen storage methods include high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, metal hydride hydrogen storage, and liquid organic hydrogen storage. Among them, liquid organic hydrogen storage technology utilizes unsaturated aromatic compounds to store hydrogen through a hydrogenation reaction and then releases hydrogen through a dehydrogenation reaction. It has significant advantages such as high hydrogen storage density, being liquid at room temperature and pressure, being able to utilize existing petrochemical infrastructure for transportation and refueling, and being reusable multiple times. It is considered one of the most commercially promising hydrogen storage technologies.

[0004] Among numerous liquid organic hydrogen storage media, carbazole compounds have become one of the most widely and deeply studied hydrogen storage systems due to their advantages such as high hydrogen storage density, good reversibility of hydrogenation and dehydrogenation reactions, and high purity of hydrogen gas produced by dehydrogenation without the generation of impurity gases such as carbon monoxide and ammonia. N-ethylcarbazole is a representative of these systems.

[0005] However, the physical properties of carbazole-based hydrogen storage carriers fluctuate with changes in the hydrogen storage state. During the hydrogenation and dehydrogenation cycle, the composition of the hydrogen storage carrier continuously changes, gradually transforming from unhydrogenated carbazole to a partially hydrogenated intermediate, and then to a fully hydrogenated product; the reverse transformation occurs during dehydrogenation. This component drift causes fluctuations in key physical properties of the hydrogen storage carrier, such as melting point and viscosity. When the content of unhydrogenated components is high, the hydrogen storage carrier is prone to crystallization at low temperatures, leading to a sharp decrease in fluidity and even blockage of pipelines. When the content of fully hydrogenated components is high, although the melting point is low, the viscosity may increase significantly, affecting pumping efficiency.

[0006] Therefore, it is necessary to propose further solutions to the above problems. Summary of the Invention

[0007] The present invention aims to provide a carbazole-based hydrogen storage carrier resistant to component drift and its application method, so as to overcome the shortcomings of the prior art.

[0008] The objective of this application is achieved through the following technical solution: This invention provides a component drift-resistant carbazole-based hydrogen storage support, comprising: Carbazole-based hydrogen storage components include: N-ethylcarbazole, incompletely hydrogenated carbazole homologues, and fully hydrogenated carbazole homologues; C10~C18 straight-chain alkanes or branched-chain alkanes; Polyvinylpyrrolidone; In the hydrogenation-dehydrogenation cycle of the hydrogen storage carrier, the proportion of the incompletely hydrogenated carbazole homologues to the total mass of the carbazole-based hydrogen storage components is maintained within a window of 5% to 35%. The window is configured such that when the hydrogen storage state of the hydrogen storage carrier undergoes cyclical changes, the fluctuation of the proportion of the incompletely hydrogenated carbazole homologue within the window can utilize the eutectic effect to suppress the fluctuation range between the solid-liquid phase transition temperatures of the hydrogen storage carrier under different hydrogen storage states to the range of -5℃ to 25℃, and suppress the viscosity fluctuation range of the hydrogen storage carrier in the temperature range of 10℃ to 40℃ to within the pumpable threshold. The C10-C18 alkanes account for 1% to 15% of the total mass of the hydrogen storage carrier; The polyvinylpyrrolidone accounts for 0.1% to 3% of the total mass of the hydrogen storage carrier.

[0009] As an improvement of the anti-component drift type carbazole-based hydrogen storage carrier of the present invention, the incompletely hydrogenated carbazole homologue accounts for 8% to 25% of the total mass of the carbazole-based hydrogen storage component.

[0010] As an improvement to the component drift-resistant carbazole-based hydrogen storage carrier of the present invention, the C10-C18 alkane is selected from one or more of dodecane, tridecane, tetradecane, and hexadecane.

[0011] As an improvement to the component drift-resistant carbazole-based hydrogen storage carrier of the present invention, the polyvinylpyrrolidone has a weight-average molecular weight of 8,000 to 50,000.

[0012] As an improvement to the component drift-resistant carbazole-based hydrogen storage carrier of the present invention, the pumpability threshold is at a temperature of 10°C and a shear rate of 100 s. -1 The measured viscosity does not exceed 200 mPa·s.

[0013] This invention also provides a method of using a component drift-resistant carbazole-based hydrogen storage carrier, wherein the hydrogen storage carrier is as described above, and the method of use includes: During the hydrogenation-dehydrogenation cycle of the hydrogen storage carrier, by controlling the hydrogenation endpoint and / or dehydrogenation endpoint, the proportion of incompletely hydrogenated carbazole homologues in the total mass of the carbazole-based hydrogen storage component in the hydrogen storage carrier is maintained within a window of 5% to 35%. The window allows the fluctuation of the proportion of the incompletely hydrogenated carbazole homologue within the window to suppress the solid-liquid phase transition temperature fluctuation of the hydrogen storage carrier within the range of -5℃ to 25℃ by utilizing the eutectic effect, and to suppress the viscosity fluctuation of the hydrogen storage carrier within the temperature range of 10℃ to 40℃ within the pumpable threshold.

[0014] As an improvement to the method of using the anti-component drift carbazole-based hydrogen storage carrier of the present invention, the steps of controlling the hydrogenation endpoint and / or dehydrogenation endpoint include: When the proportion of the incompletely hydrogenated carbazole homologue is detected to be below 5%, the hydrogenation reaction is terminated early or the dehydrogenation reaction depth is controlled so that the proportion is brought back to within the window. And / or when the proportion of the incompletely hydrogenated carbazole homologues is detected to be higher than 35%, the hydrogenation reaction is continued or the degree of dehydrogenation reaction is limited so that the proportion falls back to within the window.

[0015] An improvement to the method of using the anti-component drift carbazole-based hydrogen storage carrier of the present invention: During the cold start phase, the dehydrogenation endpoint is controlled to maintain the proportion of incompletely hydrogenated carbazole homologues in the hydrogen storage carrier within a window of 8% to 25%. During the high-load continuous operation phase, the ratio is allowed to move towards the upper limit of the 5% to 35% window; Before shutdown, control the hydrogenation endpoint to bring the ratio back to within the 8% to 25% window.

[0016] As an improvement to the method of using the anti-component drift carbazole-based hydrogen storage carrier of the present invention, the proportion of the incompletely hydrogenated carbazole homologues is monitored in real time by online gas chromatography, online liquid chromatography or near-infrared spectroscopy.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) By maintaining the proportion of incompletely hydrogenated carbazole homologues within a eutectic window of 5% to 35%, this invention can significantly suppress the fluctuations in physical properties of carbazole-based hydrogen storage carriers caused by changes in hydrogen storage state during cyclic operation. Specifically, the solid-liquid phase transition temperature fluctuation range of the hydrogen storage carrier is controlled between 5°C and 25°C, and the viscosity fluctuation range is limited to within the pumpable threshold within the operating temperature range of 10°C to 40°C. Thus, regardless of whether the hydrogen storage carrier is in the hydrogenation or dehydrogenation stage, its fluidity and phase stability can remain highly consistent, avoiding system instability caused by drastic changes in physical properties.

[0018] (2) This invention effectively reduces the low-temperature crystallization tendency of the hydrogen storage carrier through the eutectic effect formed between the incompletely hydrogenated component and the unhydrogenated and fully hydrogenated components. The eutectic effect makes the freezing point of the mixed system significantly lower than the melting point of each pure component, so that the hydrogen storage carrier can remain in a liquid or flowable state even at low temperatures. At the same time, the addition of polyvinylpyrrolidone further provides crystallization inhibition by disrupting the orderly stacking of carbazole molecules through hydrogen bonding, preventing the formation and growth of crystal nuclei. The synergistic effect of the two allows the hydrogen storage carrier to be pumped smoothly without long-term preheating during the cold start-up stage, significantly reducing the energy consumption and time cost of low-temperature start-up.

[0019] (3) The C10 to C18 straight-chain or branched alkanes in the formulation of this invention act as flowability improvers, directly reducing the absolute viscosity of the hydrogen storage carrier and playing a physical dilution role. This, combined with the flowability improvement brought about by the eutectic effect, provides a double guarantee, ensuring that the hydrogen storage carrier maintains good pumpability over a wide temperature range. Experiments show that at 10°C and a shear rate of 100 s⁻¹, the pumpability is significantly improved. -1 At that time, the apparent viscosity of the hydrogen storage carrier does not exceed 200 mPa·s, which meets the operating requirements of conventional transfer pumps and avoids pumping difficulties and pipeline blockage caused by excessive viscosity.

[0020] (4) By using the control logic of the hydrogenation endpoint and dehydrogenation endpoint in the method, the proportion of incompletely hydrogenated components in the hydrogen storage carrier is actively maintained within a specified window throughout the entire cycle. During the cold start phase, the proportion is maintained within the window of 8% to 25% to ensure low-temperature fluidity. During the high-load operation phase, the proportion is allowed to move towards the upper limit of the window to increase the hydrogen storage capacity. Before shutdown, the proportion is then returned to the window of 8% to 25% to prepare for the next start-up. This control strategy ensures that the hydrogen storage carrier maintains stable physical properties throughout long-term, multiple cycles, extends the service life of the hydrogen storage carrier, and reduces the maintenance frequency of the system. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] To address the technical problem in the prior art where carbazole-based hydrogen storage carriers experience component drift due to cyclic changes in hydrogen storage state, leading to drastic fluctuations in solid-liquid phase transition temperature and viscosity, the technical concept of this invention is as follows: The incompletely hydrogenated carbazole homologues, which are traditionally considered to need to be eliminated, are redefined as dynamic eutectic adjustment components. By actively maintaining their proportion of the total mass of the carbazole-based hydrogen storage components within a window of 5% to 35%, the physical properties of the hydrogen storage carrier are locked in a stable eutectic region by utilizing the eutectic effect formed between the incompletely hydrogenated components and the unhydrogenated and fully hydrogenated components.

[0023] Based on this concept, this invention introduces C10 to C18 straight-chain or branched alkanes as flow improvers and polyvinylpyrrolidone as crystallization inhibitors at the formulation level. Through a dual mechanism of physical dilution and hydrogen bonding, it enhances low-temperature flowability and anti-crystallization ability. At the usage level, by controlling the hydrogenation endpoint and dehydrogenation endpoint, corresponding control strategies are adopted in the cold start stage, high-load operation stage and before shutdown, and online monitoring is used to achieve real-time regulation.

[0024] Specifically, addressing the property fluctuations caused by component drift, this patent maintains the incompletely hydrogenated component within a eutectic window of 5% to 35%. This ensures that even if the composition of the hydrogen storage carrier changes, its physical properties are locked within the eutectic region. The solid-liquid phase transition temperature fluctuation of the hydrogen storage carrier under different hydrogen storage states is suppressed within 5°C to 25°C, and viscosity fluctuations are controlled within the pumpable threshold. Regarding low-temperature crystallization, the eutectic effect and the crystallization inhibition of polyvinylpyrrolidone work synergistically, allowing the hydrogen storage carrier to be pumped smoothly during cold start-up without prolonged preheating. Addressing the pumping difficulties caused by increased viscosity, the physical dilution effect of C10 to C18 alkanes, combined with the eutectic effect, provides dual protection, ensuring good pumpability of the hydrogen storage carrier over a wide temperature range. To address the issue of gradual instability of physical properties during cyclic operation, the control logic at the hydrogenation and dehydrogenation endpoints enables proactive regulation of the proportion of incompletely hydrogenated components. The segmented control strategies for cold start, high-load operation, and shutdown further optimize performance under different operating conditions, enabling the hydrogen storage carrier to maintain stable physical properties during long-term, multiple cycles.

[0025] Based on the above technical concept, this invention provides a carbazole-based hydrogen storage carrier resistant to component drift. The hydrogen storage carrier of this invention comprises a carbazole-based hydrogen storage component, C10-C18 straight-chain or branched alkanes, and polyvinylpyrrolidone.

[0026] The carbazole-based hydrogen storage component comprises N-ethylcarbazole, incompletely hydrogenated carbazole homologues, and fully hydrogenated carbazole homologues. The incompletely hydrogenated carbazole homologues include tetrahydro and octahydro products, accounting for 5% to 35% of the total mass of the carbazole-based hydrogen storage component, preferably 8% to 25%. C10-C18 alkanes are selected from one or more of dodecane, tridecane, tetradecane, or hexadecane, accounting for 1% to 15% of the total mass of the hydrogen storage carrier. Polyvinylpyrrolidone has a weight-average molecular weight of 8,000 to 50,000, accounting for 0.1% to 3% of the total mass of the hydrogen storage carrier. These components together constitute the basic formulation of the hydrogen storage carrier of this invention.

[0027] Based on the above-mentioned composition, this invention achieves self-stabilization of physical properties through eutectic window control. During the hydrogenation-dehydrogenation cycle of the hydrogen storage carrier, the proportion of incompletely hydrogenated carbazole homologues in the total mass of the carbazole-based hydrogen storage component is actively maintained within a window of 5% to 35%, preferably within a window of 8% to 25%.

[0028] This window is chosen based on the following principle: a eutectic effect exists between incompletely hydrogenated carbazole homologues and unhydrogenated and fully hydrogenated carbazole homologues. When the proportions of the three components are within a specific range, the freezing point of the mixture is significantly lower than the melting point of each pure component. By maintaining this window, even if the hydrogen storage state undergoes cyclical changes leading to fluctuations in the component proportions, the solid-liquid phase transition temperature fluctuation range of the hydrogen storage carrier is controlled within 5°C to 25°C. Within the operating temperature range of 10°C to 40°C, the viscosity fluctuation range is limited to within the pumpable threshold. According to the conventional design parameters of industrial delivery pumps, fluids below 200 mPa·s can be stably pumped without additional heating. This pumpable threshold is defined as a shear rate of 100 s at 10°C. -1 The measured viscosity does not exceed 200 mPa·s.

[0029] Therefore, regardless of whether the hydrogen storage carrier is in the hydrogenation or dehydrogenation stage, its fluidity and phase stability remain highly consistent, avoiding system instability caused by drastic changes in physical properties. At the same time, the eutectic effect makes the freezing point of the mixed system significantly lower than the melting point of each pure component, effectively reducing the low-temperature crystallization tendency of the hydrogen storage carrier. Even at low temperatures, the hydrogen storage carrier can remain in a liquid or flowable state.

[0030] Building upon this, the addition of polyvinylpyrrolidone further enhances its crystallization inhibition effect. The carbonyl group in its molecule forms hydrogen bonds with the NH groups in the carbazole-based molecules, disrupting the orderly stacking of the carbazole molecules and preventing crystal nuclei formation and growth. The synergistic effect of the eutectic effect and the crystallization inhibition of polyvinylpyrrolidone allows the hydrogen storage carrier to be pumped smoothly during the cold start phase without prolonged preheating, significantly reducing energy consumption and time costs during low-temperature startup.

[0031] Meanwhile, the addition of C10-C18 alkanes provides physical dilution, directly reducing the absolute viscosity of the hydrogen storage carrier. These long-chain alkanes possess excellent thermal stability and chemical inertness, and do not participate in side reactions or poison the catalyst under hydrogenation and dehydrogenation conditions. The physical dilution effect of alkanes, combined with the improved flowability brought about by the eutectic effect, provides a dual guarantee, ensuring that the hydrogen storage carrier maintains good pumpability over a wide temperature range, meeting the operational requirements of conventional transfer pumps, and avoiding pumping difficulties and pipeline blockages caused by excessive viscosity.

[0032] This invention also provides a corresponding method of use. During the hydrogenation-dehydrogenation cycle of the hydrogen storage carrier, the proportion of incompletely hydrogenated carbazole homologues in the total mass of the carbazole-based hydrogen storage component is maintained within a window of 5% to 35% by controlling the hydrogenation and dehydrogenation endpoints. Specifically, when this proportion is detected to be below 5%, the hydrogenation reaction is terminated early or the depth of the dehydrogenation reaction is controlled to allow the proportion to rise back within the window; when this proportion is detected to be above 35%, the hydrogenation reaction continues or the degree of dehydrogenation reaction is limited to allow the proportion to fall back within the window. During the cold start-up phase, the dehydrogenation endpoint is controlled to maintain the proportion within a window of 8% to 25% to ensure low-temperature fluidity; during high-load continuous operation, the proportion is allowed to move towards the upper limit of the 5% to 35% window to balance hydrogen storage capacity; before shutdown, the hydrogenation endpoint is controlled to bring the proportion back to the 8% to 25% window to prepare for the next start-up. The proportion of incompletely hydrogenated components is monitored in real time using online gas chromatography, online liquid chromatography, or near-infrared spectroscopy to achieve closed-loop control. The above usage method ensures that the hydrogen storage carrier maintains stable physical properties during long-term, multiple cycles, extends the service life of the hydrogen storage carrier, and reduces the maintenance frequency of the system.

[0033] In summary, this invention, through the control of the eutectic window of the carbazole-based hydrogen storage component, the improvement of the fluidity of C10-C18 alkanes, the inhibition of crystallization of polyvinylpyrrolidone, and the active regulation of the hydrogenation and dehydrogenation endpoint, transforms the incompletely hydrogenated components that traditionally need to be eliminated into performance regulating factors that can be actively controlled, fundamentally solving the problem of physical property instability of carbazole-based hydrogen storage carriers caused by changes in hydrogen storage state.

[0034] The technical solution of the present invention will be further described below with reference to specific embodiments. All raw materials used in the embodiments are commercially available industrial-grade or chemically pure products.

[0035] Example 1

[0036] This embodiment provides a component drift-resistant carbazole-based hydrogen storage carrier, the formulation of which is as follows: N-Ethylcarbazole: 50g; Incompletely hydrocarbazole homologues: 10g; Perhydrocarbazole homologues: 40g; Dodecane: 8g; Polyvinylpyrrolidone: 1g, weight average molecular weight approximately 15,000.

[0037] In the above formulation, the incompletely hydrogenated carbazole homologue is octahydro-N-ethylcarbazole, accounting for 16.7% of the total mass of the carbazole-based hydrogen storage component. The fully hydrogenated carbazole homologue is dodecahydro-N-ethylcarbazole. Dodecane accounts for 7.4% of the total mass of the hydrogen storage carrier. Polyvinylpyrrolidone accounts for 0.9% of the total mass of the hydrogen storage carrier.

[0038] The preparation method of the hydrogen storage carrier in this embodiment is as follows: Under inert gas protection, N-ethylcarbazole, perhydrocarbazole homologues, and polyvinylpyrrolidone were added to a reaction vessel, heated to 90°C, and stirred until completely melted and mixed. Then, incompletely hydrogenated carbazole homologues and dodecane were added, and stirring continued for 2 hours until a homogeneous, transparent liquid was formed. Heating was stopped, and the mixture was allowed to cool naturally to room temperature to obtain the hydrogen storage carrier.

[0039] The method of using the hydrogen storage carrier in this embodiment: The aforementioned hydrogen storage carrier was used in a hydrogenation-dehydrogenation cycle system. During the cycle, the proportion of incompletely hydrogenated carbazole homologues in the total mass of the carbazole-based hydrogen storage component was monitored in real time using online near-infrared spectroscopy. When this proportion fell below 5%, the hydrogenation reaction was terminated early or the dehydrogenation reaction depth was controlled to bring the proportion back within the specified range. When the proportion exceeded 35%, the hydrogenation reaction continued or the degree of dehydrogenation was limited to bring the proportion back within the specified range. During the cold start-up phase, the dehydrogenation endpoint was controlled to maintain the proportion of incompletely hydrogenated components within the range of 8% to 25%. During high-load continuous operation, this proportion was allowed to move towards the upper limit of the 5% to 35% range. Before shutdown, the hydrogenation endpoint was controlled to bring the proportion back to the 8% to 25% range.

[0040] Example 2

[0041] This embodiment provides a component drift-resistant carbazole-based hydrogen storage carrier, the formulation of which is as follows: N-Ethylcarbazole: 50g; Incompletely hydrogenated carbazole homologues: 15g; Perhydrocarbazole homologues: 35g; Tridecane: 10g; Polyvinylpyrrolidone: 2g, weight average molecular weight approximately 30,000.

[0042] In the above formulation, the incompletely hydrogenated carbazole homologue is octahydro-N-ethylcarbazole, accounting for 23.1% of the total mass of the carbazole-based hydrogen storage component. The fully hydrogenated carbazole homologue is dodecahydro-N-ethylcarbazole. Tridecane accounts for 9.1% of the total mass of the hydrogen storage carrier. Polyvinylpyrrolidone accounts for 1.8% of the total mass of the hydrogen storage carrier.

[0043] The preparation method and usage method are the same as in Example 1.

[0044] Example 3

[0045] This embodiment provides a component drift-resistant carbazole-based hydrogen storage carrier, the formulation of which is as follows: N-Ethylcarbazole: 50g; Incompletely hydrogenated carbazole homologues: 8g; Perhydrocarbazole homologues: 42g; Hexadecane: 6g; Polyvinylpyrrolidone: 0.5g, weight average molecular weight approximately 10,000.

[0046] In the above formulation, the incompletely hydrogenated carbazole homologue is octahydro-N-ethylcarbazole, accounting for 13.8% of the total mass of the carbazole-based hydrogen storage component. The fully hydrogenated carbazole homologue is dodecahydro-N-ethylcarbazole. Hexadecane accounts for 5.7% of the total mass of the hydrogen storage carrier. Polyvinylpyrrolidone accounts for 0.5% of the total mass of the hydrogen storage carrier.

[0047] The preparation method and usage method are the same as in Example 1.

[0048] Comparative Example 1 This comparative example uses a binary mixture of N-ethylcarbazole and dodecahydro-N-ethylcarbazole, which is common in existing technologies, without the addition of incompletely hydrogenated components, alkanes, and polyvinylpyrrolidone.

[0049] The specific formulation is: 70g of N-ethylcarbazole and 30g of dodecahydro-N-ethylcarbazole, free of alkanes and polyvinylpyrrolidone. The initial percentage of incompletely hydrogenated components is 0%, and the cycle is operated in a conventional manner without actively controlling its proportion window.

[0050] The preparation method is as follows: N-ethylcarbazole and dodecahydro-N-ethylcarbazole are heated to 150°C and melt-mixed, stirred for 5 hours and then cooled to room temperature.

[0051] The usage method is as follows: do not adopt the window control strategy, and operate according to the conventional hydrogenation-dehydrogenation cycle.

[0052] Comparative Example 2 This comparative example uses the formulation of Example 2 in the comparative document, without the addition of alkanes and polyvinylpyrrolidone.

[0053] The specific formula is: 40g of N-ethylcarbazole, 30g of dodecahydro-N-ethylcarbazole, and 30g of octahydro-N-ethylcarbazole. The incompletely hydrogenated component accounts for 30% of the total mass of the carbazole-based hydrogen storage component and does not contain alkanes or polyvinylpyrrolidone.

[0054] The preparation method is the same as that of Comparative Example 1.

[0055] The usage method is as follows: do not adopt the window control strategy, and operate according to the conventional hydrogenation-dehydrogenation cycle.

[0056] Comparative Example 3 This comparative example uses the same formulation as Example 1, but does not employ the method of use of the present invention, i.e., it does not actively control the window of incompletely hydrogenated components during the cycling process.

[0057] The formula and preparation method are the same as in Example 1.

[0058] The method of use is as follows: do not control the hydrogenation endpoint and dehydrogenation endpoint, and allow the proportion of incompletely hydrogenated components to fluctuate naturally during the cycle.

[0059] The hydrogen storage supports prepared in each embodiment and comparative example were subjected to the following performance tests: (1) Solid-liquid phase transition temperature test: Differential scanning calorimetry was used for measurement, with a heating rate of 5℃ / min. The melting point and freezing point were recorded. The test was performed once every 10 cycles during the cycle, for a total of 50 cycles, and the temperature fluctuation range was calculated.

[0060] (2) Viscosity test: The viscosity was measured using a rotational rheometer at temperatures of 10℃, 25℃ and 40℃, and a shear rate of 100s. -1 Record the apparent viscosity. Test once every 10 cycles, for a total of 50 cycles, and calculate the viscosity fluctuation range.

[0061] (3) Low temperature fluidity test: Place the hydrogen storage carrier in a -5℃ constant temperature box for 24 hours, observe whether crystallization or solidification occurs, and record the time of complete solidification.

[0062] (4) Cold start pumping test: Start the delivery pump at 5℃ and record the time to reach a stable flow rate.

[0063] (5) Cyclic stability test: 50 hydrogenation-dehydrogenation cycles were conducted. The hydrogenation conditions for each cycle were 180℃ and 7MPaH2, and the dehydrogenation conditions were 200℃ and atmospheric pressure. The hydrogenation conversion rate and dehydrogenation conversion rate for each cycle were recorded, and the conversion rate retention rate after 50 cycles was calculated.

[0064] The test results are shown in Table 1. Table 1 - Performance test results of each embodiment and comparative example As shown in Table 1, compared with Comparative Example 1, Examples 1 to 3 use a traditional binary mixture of N-ethylcarbazole and dodecahydro-N-ethylcarbazole, which does not contain incompletely hydrogenated components. Its melting point is as high as 68°C and its freezing point is 55°C. It completely solidifies at 5°C and cannot be pumped. Its physical properties fluctuate violently during the cycle, and the conversion rate retention rate is significantly lower after 50 cycles.

[0065] The embodiments of the present invention introduce incompletely hydrogenated components, alkanes, and polyvinylpyrrolidone into the formulation, and maintain the incompletely hydrogenated components within a window of 5% to 35%, thereby lowering the melting point to below 10°C, the freezing point to below 5°C, and maintaining a liquid state at a low temperature of 5°C, significantly shortening the cold start time. This fully verifies the synergistic effect of eutectic effect and polyvinylpyrrolidone crystallization inhibition.

[0066] Compared with Comparative Example 2, Examples 1 to 3 use the formulation of Comparative Example 2 in the comparative document. Although Comparative Example 2 contains incompletely hydrogenated components and has a low melting point, it does not contain alkanes and polyvinylpyrrolidone. Its viscosity at 10°C is as high as 180 mPa·s, which exceeds the pumpable threshold. It requires 15 minutes for cold start and the viscosity fluctuates greatly during the cycle.

[0067] In the embodiments of the present invention, alkanes and polyvinylpyrrolidone were further added within the same window, and the viscosity at 10°C was reduced to below 100 mPa·s, the cold start time was shortened to less than 6 minutes, and the viscosity fluctuation during the cycle was significantly narrowed, which proved the physical dilution effect of alkanes and the crystallization inhibition effect of polyvinylpyrrolidone.

[0068] Compared to Comparative Example 3, Example 1 had the same formulation, but Example 1 actively maintained the incompletely hydrogenated component within the specified window using the operating method of this invention, while Comparative Example 3 did not actively control it. The results showed that the proportion of the incompletely hydrogenated component in Comparative Example 3 naturally fluctuated more during cycling, leading to a wider melting point fluctuation range of 5°C to 45°C and a wider viscosity fluctuation range of 75 to 160 mPa·s. After 50 cycles, the conversion rate retention was significantly lower than that of Example 1. This fully demonstrates that the operating method of actively controlling the hydrogenation and dehydrogenation endpoints to maintain the specified window plays a crucial role in maintaining the long-term cycling stability of the hydrogen storage carrier.

[0069] In summary, this invention, through the organic combination of component design and operation methods, enables the hydrogen storage carrier to maintain stable physical properties during cyclic operation. The solid-liquid phase transition temperature fluctuation range is controlled within 5℃ to 25℃, and the viscosity fluctuation range of 10℃ to 40℃ is limited to within the pumpable threshold. Cold start does not require long-term preheating, and the conversion rate retention rate reaches over 95% after 50 cycles. This fundamentally solves the problem of physical property instability caused by changes in the hydrogen storage state of carbazole-based hydrogen storage carriers.

[0070] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0071] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A carbazole-based hydrogen storage carrier resistant to component drift, characterized in that, The hydrogen storage carrier comprises: Carbazole-based hydrogen storage components include: N-ethylcarbazole, incompletely hydrogenated carbazole homologues, and fully hydrogenated carbazole homologues; C10~C18 straight-chain alkanes or branched-chain alkanes; Polyvinylpyrrolidone; During the hydrogenation-dehydrogenation cycle of the hydrogen storage carrier, the proportion of the incompletely hydrogenated carbazole homologues to the total mass of the carbazole-based hydrogen storage components is maintained within a window of 5% to 35%. The window is configured such that when the hydrogen storage state of the hydrogen storage carrier undergoes cyclical changes, the fluctuation of the proportion of the incompletely hydrogenated carbazole homologue within the window can utilize the eutectic effect to suppress the fluctuation range between the solid-liquid phase transition temperatures of the hydrogen storage carrier under different hydrogen storage states to the range of -5℃ to 25℃, and suppress the viscosity fluctuation range of the hydrogen storage carrier in the temperature range of 10℃ to 40℃ to within the pumpable threshold. The C10-C18 alkanes account for 1% to 15% of the total mass of the hydrogen storage carrier; The polyvinylpyrrolidone accounts for 0.1% to 3% of the total mass of the hydrogen storage carrier.

2. The anti-component drift carbazole-based hydrogen storage carrier according to claim 1, characterized in that, The incompletely hydrogenated carbazole homologues account for 8% to 25% of the total mass of the carbazole-based hydrogen storage components.

3. The anti-component drift carbazole-based hydrogen storage carrier according to claim 1, characterized in that, The C10-C18 alkanes are selected from one or more of dodecane, tridecane, tetradecane, and hexadecane.

4. The anti-component drift carbazole-based hydrogen storage carrier according to claim 1, characterized in that, The polyvinylpyrrolidone has a weight-average molecular weight of 8,000 to 50,000.

5. The anti-component drift carbazole-based hydrogen storage carrier according to claim 1, characterized in that, The pumpability threshold is defined as a shear rate of 100 s at a temperature of 10°C. -1 The measured viscosity does not exceed 200 mPa·s.

6. A method of using a carbazole-based hydrogen storage carrier with anti-component drift capability, characterized in that, The hydrogen storage carrier is any one of claims 1 to 5, and the method of use includes: During the hydrogenation-dehydrogenation cycle of the hydrogen storage carrier, by controlling the hydrogenation endpoint and / or dehydrogenation endpoint, the proportion of incompletely hydrogenated carbazole homologues in the total mass of the carbazole-based hydrogen storage component in the hydrogen storage carrier is maintained within a window of 5% to 35%. The window allows the fluctuation of the proportion of the incompletely hydrogenated carbazole homologue within the window to suppress the solid-liquid phase transition temperature fluctuation of the hydrogen storage carrier within the range of -5℃ to 25℃ by utilizing the eutectic effect, and to suppress the viscosity fluctuation of the hydrogen storage carrier within the temperature range of 10℃ to 40℃ within the pumpable threshold.

7. The method of using the anti-component drift carbazole-based hydrogen storage carrier according to claim 6, characterized in that, The steps for controlling the hydrogenation endpoint and / or dehydrogenation endpoint include: When the proportion of the incompletely hydrogenated carbazole homologue is detected to be below 5%, the hydrogenation reaction is terminated early or the dehydrogenation reaction depth is controlled so that the proportion is brought back to within the window. And / or when the proportion of the incompletely hydrogenated carbazole homologues is detected to be higher than 35%, the hydrogenation reaction is continued or the degree of dehydrogenation reaction is limited so that the proportion falls back to within the window.

8. The method of using the anti-component drift carbazole-based hydrogen storage carrier according to claim 6, characterized in that: During the cold start phase, the dehydrogenation endpoint is controlled to maintain the proportion of incompletely hydrogenated carbazole homologues in the hydrogen storage carrier within a window of 8% to 25%. During the high-load continuous operation phase, the ratio is allowed to move towards the upper limit of the 5% to 35% window; Before shutdown, control the hydrogenation endpoint to bring the ratio back to within the 8% to 25% window.

9. The method of using the anti-component drift carbazole-based hydrogen storage carrier according to claim 6, characterized in that, The proportion of the incompletely hydrogenated carbazole homologues is monitored in real time by online gas chromatography, online liquid chromatography, or near-infrared spectroscopy.

Images