Catalyst for efficiently catalyzing hydrodenitrogenation of quinoline

Abstract

The invention discloses a method for preparing n-propyl cyclohexane by catalyzing hydrodenitrogenation of quinoline. According to the method, the n-propyl cyclohexane is prepared by catalyzing a 1, 4-dioxane solution of quinoline by using a nano functional catalyst x%-Ni-y%-Mo-z%-WOx at m%-GO-SAPO-34 through a one-step hydrodenitrogenation reaction. According to the catalyst, a gel method and an impregnation method are combined, non-noble metals Ni, Mo and W are ingeniously loaded on SAPO-34 doped with sulfuric acid sulfonated graphene, a functional nano-catalyst is formed, and a gas-phase hydrodenitrification experiment shows a good effect. Under optimized conditions, the highest selectivity of the main product n-propyl cyclohexane can reach 81.35%, and at the moment, the conversion rate of quinoline reaches up to 99.95%, namely the yield of the main product n-propyl cyclohexane reaches up to 81.31%. The method is short in process route, simple in reaction equipment and operation method, mild in reaction condition, short in reaction time and low in energy consumption, and the catalyst is simple and controllable in synthesis, low in cost, good in stability and capable of being recycled. The main product of the method is pure and easy to separate and purify, the expected economic benefit is very considerable, and the method can be used for a petroleum hydrogenation refining process and well achieves the effect of one-step hydrogenation nitrogen removal of quinoline.

Description

Technical Field

[0001] This invention relates to the preparation of catalysts and n-propylcyclohexane, specifically to the preparation of a novel high-efficiency catalyst and a method for one-step selective hydrogenation catalytic denitrogenation of quinoline to n-propylcyclohexane. Background Technology

[0002] Energy use and processing technologies have always been a focus of the scientific community. How to effectively utilize clean energy and maximize the utilization rate of fossil fuels is a core technology for the sustainable survival and development of humankind in today's society. Although new energy technologies have provided support for the development of some new energy sources, the vast majority of industries still rely on fossil fuels, mainly because fossil fuels have high direct processing and utilization rates, such as petroleum refining. Petroleum contains approximately 0.50 wt% nitrogen, and nitrogen-containing compounds mainly include pyridine, quinoline, isoquinoline, acridine, and indole. Coal-based crude oil refers to the primary liquid obtained after initial coal mining through various high-temperature chemical reactions and specialized processes. It is divided into coal tar, indirect coal liquefaction oil, and direct coal liquefaction oil. Hydrogenation refining of coal tar to produce high-energy-density fuels has become a highly efficient development path for the coal-based crude oil industry. Coal tar has a nitrogen content as high as 1.30 wt%. Although substances like petroleum and coal have relatively low nitrogen content, the presence of nitrogen compounds poses a significant threat to energy production processes. On one hand, it accelerates catalyst poisoning and deactivation; on the other hand, it remains in the finished products and, upon use, generates nitrogen oxides that pollute the atmosphere. Therefore, the efficient removal of nitrogen compounds has become a key research focus in the fields of chemical technology and energy.

[0003] There are many methods for removing nitrogen-containing compounds, such as extraction, adsorption, oxidation, biological methods, and catalytic hydrotreating. Extraction, adsorption, and biological methods directly remove nitrogen-containing compounds, achieving denitrification, but significantly reduce the hydrocarbon and organic matter content of petroleum, thus lowering the efficiency of petroleum products. Oxidation methods convert nitrogen in organic matter into nitro groups, leaving nitrogen in another form in the petroleum product, thus failing to achieve fundamental removal. Catalytic hydrotreating refers to the process where nitrogen-containing organic matter undergoes a hydrogenation reaction under the action of a unique catalyst, removing nitrogen and transforming it into alkanes. This effectively converts nitrogen into ammonia while effectively retaining the hydrocarbon and organic matter content in the petroleum product, making it an ideal denitrification conversion method, but it is highly dependent on the catalyst.

[0004] Numerous studies on the hydrogenation process of quinolines have been conducted by researchers both domestically and internationally. Traditional quinoline hydrogenation methods mostly focus on the formation of 1,2,3,4-tetrahydroquinoline. Noble metals such as Pt, Au, Pd, Ru, and Rh exhibit significant activity for quinoline hydrogenation, while non-noble metals such as Ni, Cu, and Co also possess some activity. With appropriate supports such as Al₂O₃, SiO₂, and activated carbon, quinoline conversion can be achieved under mild conditions. However, the competitive hydrogenation of aromatic and pyridine rings presents a challenge. To address the high cost of noble metal catalysts, Wang Bowen et al. from Tianjin University synthesized a nitrogen-boron dual-doped carbon nanotube catalyst to achieve liquid-phase hydrogenation of quinoline [CN 115974780A]. Under the direct reduction of hydrazine hydrate, the quinoline conversion rate exceeded 75%, and the selectivity for 1,2,3,4-tetrahydroquinoline reached 75%. Zheng Huajun et al. from Zhejiang University of Technology achieved electrocatalytic hydrogenation of quinoline by designing a self-supporting CoP nanowire catalytic electrode [CN 118957636A]. In a strongly alkaline 1,4-dioxane solvent, they achieved a selectivity of up to 99.99% for 1,2,3,4-tetrahydroquinoline under mild conditions. The main product has wide applications in pesticides, dyes, and alkaloids. However, the nitrogen in the molecule was not fundamentally removed, so it cannot directly provide any beneficial effects in petrochemicals.

[0005] Deep quinoline hydrodenitrogenation mainly refers to the removal of nitrogen from organic matter during hydrogenation, which cannot be achieved by noble metal hydrogenation catalysts alone. Furthermore, the pyridine ring in quinoline and the nitrogen element exhibit unequal sp[s] properties. 2 The hybrid form exists, and the lone pair electrons are not bound, making it easy to combine with protons and thus exhibiting a certain degree of basicity. The C=N double bond energy in quinoline is as high as 615 kJ / mol, while the CN bond energy in the branched molecule is only 305 kJ / mol. Therefore, the quinoline molecule first needs to add hydrogen to form a CN bond, and then the CN bond is broken through the Hofmann elimination or nucleophilic substitution reaction mechanism to form free ammonia.

[0006] Research on the hydrogenation and denitrification of quinolines began in 1981 when Schulz et al. in Germany first proposed that Ni-W bimetallic loading on Al2O3 could be used for the hydrogenation and denitrification of quinolines (Studies in Surface Science and Catalysis, 1981, 7, 1474-1475). In the same year, Satterfield et al. also proposed that quinoline first undergoes hydrogenation to form 1,2,3,4-tetrahydroquinoline, then undergoes hydrogenation saturation to form decahydroquinoline, followed by CN bond cleavage to form o-propylcyclohexaneamine, which can achieve the removal of NH3 to form propylcyclohexene, and then hydrogenation to form n-propylcyclohexane (Industrial Engineering Chemistry Process Design and Development, 1981, 20, 53-62). Nikulshin et al. experimentally verified Ni6-PW... 12 S / C1 / Al2O3 can be used for the hydrodenitrification of quinoline, exhibiting optimal denitrification performance. The key to denitrification depends on the appropriate Ni / W ratio and suitable carbon content (Applied Catalysis B: Environmental, 2015, 176-177, 374-384). Minaev et al. synthesized NiWS / Al2O3 catalysts for the hydrodenitrification of quinoline, specifically studying the effect of the Ni / W ratio on quinoline hydrodenitrification. They found that the catalytic effect was best when the Ni / (Ni+W) ratio in the catalyst was 0.24 (Applied Catalysis A: General, 2015, 505, 456-466). Minaev et al. subsequently discovered that introducing P into the catalyst can benefit the hydrodenitrification of quinoline. The Ni-PW / Al2O3 catalyst is suitable for deep denitrification of quinoline, with a product yield reaching 90% (Catalysis in Industry, 2017, 9, 146-155), but the catalyst is prone to deactivation. Recently, Liu Chunting et al. in my country selected sulfuric acid-modified kaolin as a support and loaded Ni / Mo bimetallic catalyst for the hydrodenitrification of quinoline. They found that sulfuric acid modification can effectively improve the dispersion of the supported metal and enhance the neutralization of the released ammonia. The conversion rate of quinoline was as high as 95%, and the denitrification rate was as high as 62% (Fuel, 2025, 381, 133407).

[0007] The main challenges of one-step hydrogenation denitrification of quinolines are as follows: First, there is significant competition between the benzene ring and the nitrogen-containing ring in quinoline during hydrogenation. Under noble metal and low-temperature conditions, the aromatic ring is more likely to be hydrogenated first, making subsequent hydrogenation of intermediate products more difficult. Second, the nitrogen-containing ring undergoes cracking. Hydrogenation of the nitrogen-containing ring must be completed before ring cracking occurs, requiring a catalyst with suitable hydrogenation activity. Simultaneously, the influence of promoters should be maximized to facilitate the cracking of the nitrogen-containing ring. Only after the heterocycle is opened to generate -NH2 can further deamination and nitrogen removal occur. Third, denitrification causes a significant change in the pH of the hydrogenation system. The release of large amounts of ammonia alters the acidity or alkalinity of the solution. If the catalyst itself lacks acidic sites or the solution is acidic, the release of ammonia may poison the catalyst, thereby reducing its activity. Therefore, liquid-phase hydrogenation denitrification of quinolines is not advantageous; gas-phase hydrogenation denitrification may be more effective. Analysis of domestic and international research reveals that, considering both catalyst cost and deactivation issues, a suitable catalyst model for quinoline hydrodenitrification is one that achieves moderate activity under high temperature and pressure, high dispersion of multiple non-precious metals, and appropriate additives. The reaction process for quinoline hydrodenitrification is as follows: Figure 1 As shown, Qui represents quinoline, THQui represents tetrahydroquinoline, o-APB represents o-aminopropylbenzene, PB represents propylbenzene, o-APCH represents o-aminopropylcyclohexane, and PCH represents propylcyclohexane.

[0008] remove Figure 1 Besides the substances shown in the process, other intermediate products may be generated during the hydrodenitrification of quinoline, such as isopropylbenzene and 1-n-propyl-1-cyclohexene. This may be due to incomplete hydrogenation during the process. The generation of ammonia can weaken the active sites of the catalyst, leading to incomplete hydrogenation. Therefore, the catalyst's resistance to poisoning and high activity are technical challenges in the hydrodenitrification of quinoline. Wen Guangming et al. of China National Petroleum Corporation proposed a Zn / Ni / W mixed metal catalyst supported on an AlPO-4-5 phosphorus aluminum molecular sieve and alumina mixed support for the hydrodenitrification of quinoline [CN 119951576A]. They proposed that the optimal hydrogenation activity mainly depends on metallic Ni, and that a highly active hydrogenation phase is the decisive factor in improving the yield of quinoline hydrodenitrification products. Therefore, multi-metal mixed functional catalysts may be the ideal choice for quinoline hydrodenitrification. Considering the needs of denitrification, introducing acidic sites or sulfuric acid modification will be better measures to improve the denitrification effect.

[0009] Currently, no ideal catalyst for one-step hydrogenation denitrification of quinoline has been effectively reported. Some catalysts have high initial activity but are easily poisoned and not durable, while others are durable but have unsatisfactory selectivity and yield of the main product. Therefore, the technology for hydrogenation denitrification of quinoline still needs continuous experimental trials and optimization, which has important scientific significance in the hydrogenation refining process of petrochemicals.

[0010] From the perspective of heterogeneous catalysis technology, improving the yield of the main product is key. The cost and reusability of the catalyst are also important indicators for its industrialization. Using non-precious metals as the active component of the catalyst can significantly reduce costs. Catalytic experiments, through the preparation and optimization of the catalyst, aim to achieve high conversion rates and high selectivity for the main product under relatively mild conditions. Simultaneously, by selecting suitable solvents, the reactants are processed to the greatest extent possible, ensuring a green and pollution-free process, easy product separation, and achieving energy-saving and high-efficiency goals. Summary of the Invention Attached image description: Figure 1 It is the hydrogenation and denitrification process of quinoline.

[0011] To address the shortcomings of existing one-step hydrogenation denitrogenation catalytic methods for the preparation of n-propylcyclohexane from quinoline, the present invention aims to provide a novel functional catalyst suitable for the catalytic hydrogenation denitrogenation of quinoline to n-propylcyclohexane, achieving the catalytic conversion requirements of highly efficient hydrogenation denitrogenation of quinoline, with high selectivity for the main product n-propylcyclohexane, and low catalyst cost.

[0012] The present invention also aims to provide a method for the hydrogenation and denitrogenation of quinoline to prepare n-propylcyclohexane with mild reaction conditions, simple process flow, low raw material cost, simple and easy-to-prepare catalyst, environmentally friendly and pollution-free process, and green and environmentally friendly technology. It is expected to be used in the future for the efficient removal of nitrogen-containing compounds in petroleum refining, improve the efficiency of petroleum hydrogenation refining, and at the same time increase the utilization value of oil products and reduce pollution.

[0013] The objective of this invention is achieved through the following technical solution: A novel, highly efficient catalyst and a method for one-step selective hydrogenation catalysis of quinoline denitrogenation to n-propylcyclohexane were developed, using a non-noble metal bimetallic catalyst, Ni and Mo, as the active site, and WO3 as the catalyst. x As an auxiliary agent, GO (graphene-doped GO), after sulfonation, is thoroughly mixed with the SAPO-34 molecular sieve support to form a functional, highly efficient nano-catalyst for the one-step selective hydrogenation catalysis of quinoline to n-propylcyclohexane. In the presence of 1,4-dioxane as a solvent, quinoline undergoes one-step hydrogenation and denitrogenation to generate n-propylcyclohexane, with the 1,4-dioxane solution containing quinoline having a mass fraction of 1%–5%.

[0014] Furthermore, the catalyst is prepared from the following raw material components in mass percentage: in: The non-precious metal active component Ni is derived from soluble Ni(NO3)2·6H2O; the metallic Mo is derived from (NH4)6Mo7O. 24 ·Decomposition of 4H2O; WO x It is derived from the decomposition of ammonium metatungstate; the nano-graphene was purchased directly from Suzhou Carbon-Feng Graphene Technology Co., Ltd.; the SAPO-34 molecular sieve is rich in four elements: Si, Al, P, and O, and is derived from self-synthesis by using aluminum isopropoxide, phosphoric acid, tetraethyl orthosilicate, tetraethylammonium hydroxide, etc., through a hydrothermal method.

[0015] Furthermore, the catalyst is loaded in 1.0g increments each time.

[0016] Furthermore, in the hydrogenation denitrification experiment of quinoline, the preferred reaction temperature is 310–410 °C, the preferred reaction time is 180 min, and the preferred liquid hourly space velocity is 12 h⁻¹. -1 .

[0017] Furthermore, the mass fraction of quinoline is preferably 1-5%.

[0018] The nano-functional catalyst used in this invention exhibits catalytic effects in both the surface and inner layers of Ni-Mo metal components with different proportions. Sulfated graphene is mixed into the support, but the catalyst with the best catalytic effect for hydrogenation and denitrogenation is 2%-Ni-3%-Mo-5%-WO. x @6%-GO-SAPO-34, meaning that the mass of metallic Ni accounts for 2% of the total catalyst mass, metallic Mo accounts for 3%, metallic W accounts for 5%, and sulfuric acid sulfonated GO accounts for 6%, the corresponding quinoline conversion rate is as high as 99.95%, the selectivity of the main product n-propylcyclohexane is as high as 81.35%, and the yield of the main product n-propylcyclohexane is as high as 81.31%. Furthermore, its high concentration in the reaction product solution facilitates subsequent product separation and purification, which is beneficial for the industrial-scale promotion of the quinoline hydrodenitrification technology and the one-step production of n-propylcyclohexane. The reaction solution mentioned in this invention uses 1,4-dioxane as the solvent, and the optimal mass fraction of quinoline is 3%. This results in a relatively small catalyst mass, low cost, good effect, and the catalyst can be recycled more than 4 times.

[0019] The preferred additive of this invention is WO. x This is beneficial for improving the high selectivity of the main product n-propylcyclohexane and the stability of the catalyst. Characterization revealed that with the increase of WO3... xThe introduction of these materials improves both the dispersion of the metal and the acidic sites of the catalyst. The introduction of Mo metal significantly enhances the catalytic activity of Ni metal while also mitigating surface defects. The introduction of sulfonated graphene increases the acidic sites on the catalyst, facilitating deamination during hydrogenation, and also promotes high dispersion of bimetallic active sites, resulting in a richer and more refined microstructure. Furthermore, the selection of the support material and its pore size effectively suppresses the diffusion of large organic molecules, preventing sintering and poisoning deactivation of the active sites on the catalyst surface.

[0020] The beneficial effects of this invention are as follows: 1. This invention uses the nano-functional catalyst Ni-Mo-WO x @GO-SAPO-34, under relatively mild gas-phase conditions, enables one-step hydrogenation and denitrogenation catalysis of quinoline to prepare n-propylcyclohexane, achieving high quinoline conversion and selectivity for the main product n-propylcyclohexane, which is beneficial for upgrading the hydrodenitrogenation technology in petroleum refining.

[0021] 2. The reaction raw materials and catalysts of this invention are inexpensive and readily available, and all catalysts have good stability and excellent recyclability.

[0022] 3. The reaction conditions are relatively mild, the process is clear, and the operation is simple and convenient. It can be used for continuous production, meeting the requirements of industrial production, and is particularly beneficial for the hydrogenation removal of nitrogen-containing organic matter.

[0023] 4. It is green and pollution-free, with high yield, high product purity, easy separation, and environmentally friendly process, meeting the requirements of green chemical processes. Detailed Implementation

[0024] The following examples are intended to further illustrate the content of this invention, and this content also falls within the scope of protection of the claims of this invention.

[0025] Catalyst preparation and hydrogenation method: Preparation of SAPO-34 support material: Accurately weigh 1.20 g of aluminum isopropoxide and 1.20 g of tetraethyl orthosilicate and dissolve them in 50 mL of deionized water. While continuously stirring, add 10 mL of concentrated phosphoric acid dropwise using a separatory funnel. Separately, accurately weigh 0.30 g of tetraethylammonium hydroxide and dissolve it in a beaker containing 20 mL of deionized water. Carefully mix the two solutions while vigorously stirring to form a homogeneous gel. Carefully age the gel for 6 hours and then transfer it to a crystallization vessel. After sealing, maintain the vessel at 200 °C for 48 hours for continuous crystallization. After cooling, remove the solid, wash it three times with a small amount of deionized water, and then transfer it to a vacuum drying oven at 60 °C for 24 hours for continuous drying. The dried support powder is ground and then calcined in a muffle furnace at 600 °C for 24 hours to form a gray powder, which is the SAPO-34 molecular sieve, maintaining the Al, P, and Si ratio in the support.

[0026] Take a certain mass of Ni(NO3)2·6H2O and (NH4)6Mo7O respectively 24 • Dissolve 4H₂O crystals in a small amount of deionized water. Separately, dissolve a certain amount of ammonium metatungstate in a small amount of hydrogen peroxide. Mix the two thoroughly and add the prepared carrier powder. After continuous impregnation and stirring for 24 hours, evaporate some of the deionized water and transfer to a 110℃ oven for continuous drying overnight. After cooling, transfer to a muffle furnace and calcine at 300℃ for 6 hours. After cooling, grind repeatedly and transfer to a tube furnace filled with nitrogen and calcine at 600℃ for 6 hours to form the oxide crystal phase. Then, reduce with hydrogen at the same temperature for 3 hours to form the nano-functional catalyst Ni-Mo-WO₄. x @GO-SAPO-34, store in a sealed, airtight container. To accurately measure the mass fraction of each component in the catalyst, use x%-Ni-y%-Mo-z%-WO. x @m%-GO-SAPO-34, where x% represents the mass fraction of metallic Ni in the catalyst, y% represents the mass fraction of metallic Mo in the catalyst, and z% represents the mass fraction of WO in the catalyst. x The mass fraction (calculated by the mass of W), m% represents the mass fraction of GO sulfonated with sulfuric acid in the catalyst. Catalyst A represents 0%-Ni-3%-Mo@SAPO-34, catalyst B represents 1%-Ni-3%-Mo@SAPO-34, catalyst C represents 2%-Ni-3%-Mo@SAPO-34, catalyst D represents 3%-Ni-3%-Mo@SAPO-34, catalyst E represents 3%-Ni-2%-Mo@SAPO-34, catalyst F represents 3%-Ni-1%-Mo@SAPO-34, and catalyst G represents 3%-Ni-0%-Mo@SAPO-34. Among them, catalysts A to G are all WO-free. x And sulfuric acid sulfonated GO components.

[0027] The following experiments were conducted on the hydrogenation reaction of quinoline under different reaction conditions using different catalysts. Example 1: A high-temperature, high-pressure fixed-bed hydrogenation apparatus was selected. The reaction tube was 60 cm long, with an inner diameter of 5 mm and an outer diameter of 15 mm. The catalyst loading was 1.0 g. First, a 3% (w / w) quinoline 1,4-dioxane solution was prepared and connected to the system via a high-pressure liquid phase pump. After catalyst A was loaded, the temperature was set to 300°C, the hydrogen pressure was adjusted to 4.0 MPa, and the catalyst was continuously activated for 1 hour. Then, the temperature was increased to 350°C. Maintaining a hydrogen-to-oil ratio of 500:1, the quinoline solution was introduced via the high-pressure liquid phase pump at a liquid hourly space velocity (LISH) of 12 h⁻¹. -1 After 6 hours, samples were taken for analysis. Quantitative analysis was performed using gas chromatography with internal standard method (n-decane as internal standard). The conversion rate and selectivity of each substance were calculated, as detailed in Table 1.

[0028] Example 2: Catalyst B was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 1.

[0029] Example 3: Catalyst C was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 1.

[0030] Example 4: Catalyst D was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 1.

[0031] Example 5: Catalyst E was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 1.

[0032] Example 6: Catalyst F was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 1.

[0033] Example 7: Catalyst G was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 1.

[0034] Table 1. Detailed results of Examples 1-7

[0035] Analysis and comparison of the data show that the nanocatalyst containing only Mo has a low quinoline conversion rate but a high selectivity for the intermediate product o-APB, indicating that Mo may be beneficial for CN bond breaking. However, the selectivity for PB and PCH is not high, indicating insufficient denitrification ability of the catalyst. As the Ni content increases, the conversion rate gradually increases, indicating improved hydrogenation conversion capacity. Catalyst D, containing the same mass fraction of Ni and Mo, achieves a conversion rate of 87.42%, with a slight improvement in the selectivity of the intermediate product o-APB, but the selectivity for PB and PCH remains low. Comparing the effects of catalysts E, F, and G, the conversion rate did not decrease significantly, but the selectivity for THQui increased significantly. The selectivity for o-APB decreased with decreasing Mo mass fraction, indicating that Ni is beneficial for hydrogenation but does not significantly affect CN bond breaking. Catalysts C, D, and E, which introduce WO, are the preferred choices. x To improve catalytic efficiency.

[0036] Impregnation method to introduce metal WO x Different catalysts are formed using the methods described above, with appropriate control of the ammonium metatungstate input mass. Catalyst H represents 2%-Ni-3%-Mo-4%-WO₂. x@SAPO-34, Catalyst I represents 2% Ni-3% Mo-5% WO x -@SAPO-34, catalyst J represents 2% Ni-3% Mo-6% WO x @SAPO-34, catalyst K represents 3% Ni-3% Mo-4% WO x @SAPO-34, catalyst L represents 3%-Ni-3%-Mo-5%-WO x @SAPO-34, catalyst M represents 3%-Ni-3%-Mo-6%-WO x @SAPO-34, catalyst N represents 3% Ni-2% Mo-4% WO x @SAPO-34, catalyst O represents 3% Ni-2% Mo-5% WO x @SAPO-34, catalyst P represents 3% Ni-2% Mo-6% WO x @SAPO-34. Catalysts H to P do not contain sulfuric acid-sulfonated graphene.

[0037] Example 8: Catalyst H was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 2.

[0038] Example 9: Catalyst I was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 2.

[0039] Example 10: Catalyst J was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 2.

[0040] Example 11: Catalyst K was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 2.

[0041] Example 12: Catalyst L was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 2.

[0042] Example 13: Catalyst M was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 2.

[0043] Example 14: Catalyst N was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 2.

[0044] Example 15: Catalyst O was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 2.

[0045] Example 16: Catalyst P was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 2.

[0046] Table 2 Detailed results of Examples 8-16

[0047] The experimental results show that when metal W is introduced into the catalyst, the selectivity of the denitrification products PB and PCH tends to increase significantly. Meanwhile, the selectivity of the intermediate product o-APB is significantly affected by the mass fraction of tungsten. Specifically, when Ni:Mo:W = 2:3:5, the selectivity of o-APB is relatively low, possibly due to the greater activity of Mo. At this point, the selectivity of PCH is higher, but the selectivity of subsequent intermediate product o-APCH still has a certain proportion. Although the denitrification rate increases to some extent, the selectivity of the denitrification products remains unsatisfactory. The breaking of CN bonds in heterocycles is also affected by the Ni to Mo ratio. When the content of metallic Ni increases significantly, although the overall conversion rate of the reaction improves, the sum of the selectivities of intermediate products o-APB and o-APCH does not decrease, while the sum of the selectivities of denitrification products PB and PCH does not increase. This indicates that the increase in denitrification products cannot be achieved solely by increasing hydrogenation activity; the disintegration of heterocycles and the removal of nitrogen must be achieved first. The introduction of tungsten-containing metallic species into the catalyst significantly increases the acidic sites of the catalyst. The best denitrification effect occurs when the ratio of Ni, Mo, and W is 2:3:5, at which point the sum of the selectivity of the denitrification products PB and PCH is the highest.

[0048] To further enhance the denitrification ability of the catalyst, we selected sulfonated graphene as an introduction into the catalyst preparation process. The specific procedure is as follows: 2.00 g of graphene powder was accurately weighed and added to a round-bottom flask containing 200 mL of 6 mol / L sulfuric acid solution. The solution was refluxed at 90 °C with continuous stirring for 6 hours. After cooling, the solid was carefully filtered to obtain the solid. The graphene powder was washed with a large amount of deionized water until neutral. The solid powder was dried and repeatedly ground for later use to obtain sulfonated graphene sulfuric acid powder. Separately, 1.20 g of aluminum isopropoxide and 1.20 g of tetraethyl orthosilicate were accurately weighed and dissolved in 50 mL of deionized water. While maintaining continuous stirring, 10 mL of concentrated phosphoric acid was added dropwise using a separatory funnel, along with a certain mass of sulfonated graphene sulfuric acid powder, and stirred until a uniform slurry was formed. Separately, accurately weigh 0.30 g of tetraethylammonium hydroxide and dissolve it in a beaker containing 20 mL of deionized water. Carefully mix the two solutions while maintaining vigorous stirring to form a homogeneous gel. Carefully age the gel for 6 hours, then transfer it to a crystallization vessel. Seal the vessel and maintain continuous crystallization at 200°C for 48 hours. After cooling, remove the solid, wash it three times with a small amount of deionized water, and then transfer it to a vacuum drying oven at 60°C for 24 hours. The dried support powder is then ground and calcined in a muffle furnace at 600°C for 24 hours to form a gray powder, which is the GO-SAPO-34 molecular sieve, maintaining the Al, P, and Si ratio in the support. The subsequent introduction of metals Ni, Mo, and W follows the same method to form nanocatalysts Q to U. Here, catalyst Q represents 2%-Ni-3%-Mo-5%-WO. x @4%-GO-SAPO-34, catalyst R represents 2%-Ni-3%-Mo-5%-WO x @5%-GO-SAPO-34, catalyst S represents 2%-Ni-3%-Mo-5%-WO x @6%-GO-SAPO-34, catalyst T represents 2%-Ni-3%-Mo-5%-WO x @7%-GO-SAPO-34, catalyst U represents 2%-Ni-3%-Mo-5%-WO x @8%-GO-SAPO-34.

[0049] Example 17: Catalyst Q was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 3.

[0050] Example 18: Catalyst R was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 3.

[0051] Example 19: Catalyst S was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 3.

[0052] Example 20: Catalyst T was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 3.

[0053] Example 21: Catalyst U was selected, and the reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 3.

[0054] Table 3 Detailed results of Examples 17-21

[0055] The experimental results above show that the denitrification effect of the catalyst is significantly increased after the introduction of sulfonated GO. This is manifested in a significant increase in the sum of the selectivities of the denitrification products PB and PCH, while the sum of the selectivities of the intermediate products o-APB and o-APCH is significantly decreased. This indicates that the introduction of sulfonated GO into the catalyst is beneficial to the denitrification process and the formation of the main product PCH. When the content of sulfonated GO in the catalyst exceeds 6% and continues to increase, the conversion rate of the reaction decreases significantly. This may be because excessive sulfonated GO causes blockage of the pores of the catalyst support, which is not conducive to the surface diffusion of reactants during catalyst contact, thus reducing the conversion rate. Simultaneously, the increased selectivity of PB may be due to some active sites being covered by excessive sulfonated GO, resulting in a slight adjustment in product distribution without a decrease in the denitrification rate. In summary, catalyst S exhibits the best catalytic performance, with the sum of the selectivities of PCH and PB approaching 90%.

[0056] Using catalyst S, namely 2%-Ni-3%-Mo-5%-WO x @6%-GO-SAPO-34, continue to investigate the effects of reaction conditions or other factors. Catalytic performance data under different reaction conditions with varying reaction temperature or hydrogen pressure are listed in Table 4.

[0057] Example 22: Catalyst S was selected, and the reaction temperature was selected as 310℃. Other reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 4.

[0058] Example 23: Catalyst S was selected, and the reaction temperature was selected as 330℃. Other reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 4.

[0059] Example 24: Catalyst S was selected, and the reaction temperature was selected as 370℃. Other reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 4.

[0060] Example 25: Catalyst S was selected, and the reaction temperature was selected as 390℃. Other reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 4.

[0061] Example 26: Catalyst S was selected, and the reaction temperature was selected as 410℃. Other reaction feed and hydrogenation reaction conditions were the same as in Example 1. The conversion rate and selectivity data of the relevant species were calculated and are shown in Table 4.

[0062] Table 4 Effect of changing reaction temperature

[0063] The experimental results above indicate that below 350℃, the conversion rate is low, the reaction is incomplete, and the selectivity of THQui increases, while the selectivity of the denitrification products PB and PCH remains essentially unchanged, suggesting that the reaction is not complete at low temperatures. Above 350℃, the reaction is too fast, and the denitrification efficiency is high, but the selectivity of products PB and PCH decreases slightly, while the selectivity of other products increases, possibly due to the formation of other compounds at high temperatures. Similarly, we also tried changing the hydrogen pressure in the reaction and found that at low pressure, not only is the reaction incomplete, but the selectivity of the main product is also less than ideal.

[0064] Using catalyst S, namely 2%-Ni-3%-Mo-5%-WO x @6%-GO-SAPO-34 was used to investigate the stability and recycling performance of the catalyst. The used catalyst was separated from the reaction product, dried, calcined, and activated in hydrogen. Conversion and selectivity data of relevant species were obtained under the same feed mass and hydrogenation reaction conditions. The obtained catalytic performance data are listed in Table 5.

[0065] Example 27: Catalyst S was reactivated after use, i.e., the first cycle. Other reaction conditions were the same as in Example 1. Catalytic performance data are shown in Table 5.

[0066] Example 28: Catalyst S was reactivated after use, i.e., used for the second time. Other reaction conditions were the same as in Example 1. Catalytic performance data are shown in Table 5.

[0067] Example 29: Catalyst S was reactivated after use, i.e., used for the third time. Other reaction conditions were the same as in Example 1. Catalytic performance data are shown in Table 5.

[0068] Example 30: Catalyst S was reactivated after use, i.e., the fourth cycle was used. Other reaction conditions were the same as in Example 1. Catalytic performance data are shown in Table 5.

[0069] Example 31: Catalyst S was reactivated after use, i.e., the 5th cycle. Other reaction conditions were the same as in Example 1. Catalytic performance data are shown in Table 5.

[0070] Table 5 Performance of Recycling

[0071] Comparing the effects of catalyst recycling, it can be seen that this catalyst does not deactivate even after 5 reuses, and the conversion rate remains above 95%. Due to repeated reuse, the selectivity of the byproducts is higher in the 5th reuse, leading to a gradual decrease in the selectivity of the product PCH and a gradual increase in the selectivity of the intermediate product THQui. The sum of the selectivities of the intermediate products o-APB and o-APCH gradually increases, indicating that the denitrification effect of the catalyst is weakening. Therefore, the catalytic activity of catalyst S is stable and can be recycled at least 4 times.

[0072] To investigate the effect of different solvents on the reaction system, solvents with different polarities were selected to carry out hydrogenation and denitrification under the same conditions, as follows.

[0073] Example 32: Catalyst S was selected, and n-heptane was selected as the solvent. Other reaction conditions were the same as in Example 1. Catalytic performance data are shown in Table 6.

[0074] Example 33: Catalyst S was selected, cyclohexane was selected as the solvent, and other reaction conditions were the same as in Example 1. Catalytic performance data are shown in Table 6.

[0075] Example 34: Catalyst S was selected, ethyl acetate was selected as the solvent, and other reaction conditions were the same as in Example 1. Catalytic performance data are shown in Table 6.

[0076] Example 35: Catalyst S was selected, and tetrahydrofuran was selected as the solvent. Other reaction conditions were the same as in Example 1. Catalytic performance data are shown in Table 6.

[0077] Example 36: Catalyst S was selected, ethanol was selected as the solvent, and other reaction conditions were the same as in Example 1. Catalytic performance data are shown in Table 6.

[0078] Table 6 Catalytic effects under different solvents

[0079] The above examples demonstrate that solvent polarity affects catalytic performance. Non-polar solvents exhibit relatively low conversion rates and main product selectivity, while increasing polarity significantly improves both. Therefore, selecting a highly polar solvent promotes the one-step hydrodenitrogenation of quinoline. Considering the presence of quinoline in oil products, solvents containing sulfur (S) or nitrogen (N) such as dimethyl sulfoxide or acetonitrile were not chosen to avoid affecting catalyst activity and denitrogenation rate calculations. Comparatively, we also tested the one-step hydrodenitrogenation effect at quinoline mass fractions of 1%, 2%, 4%, and 5%, finding that the main product selectivity distribution remained largely unchanged.

[0080] In summary, this invention focuses on the preparation of a nanocatalyst using SAPO-34 as a carrier, doped with sulfuric acid-sulfurized graphene, and simultaneously introducing multiple metal components to form a composite. It cleverly utilizes non-noble metals Ni and Mo as active sites for hydrogenation and denitrogenation, and introduces WO3... x As an auxiliary agent, it forms x%-Ni-y%-Mo-z%-WO x The @m%-GO-SAPO-34 catalyst, using 1,4-dioxane as a solvent, enables one-step hydrogenation and denitrogenation of quinoline to n-propylcyclohexane, achieving a maximum selectivity of 81.35% and a conversion rate as high as 99.95%. The yield of the main product, n-propylcyclohexane, is as high as 81.31%. The catalyst is inexpensive, avoiding the use of precious metals such as Ru, Pd, and Pt. The process conditions are suitable, and the expected economic benefits are considerable, making it significant for industrial applications. This method features a short process route, simple reaction equipment and operation, relatively mild reaction conditions (optimal reaction temperature 350℃, hydrogen pressure 4.0 MPa), short reaction time, and a simple, controllable, and synthesizable catalyst with good stability and recyclability. The product is relatively pure, easy to separate and purify, and environmentally friendly, making it highly suitable for the industrial application of quinoline hydrogenation and denitrogenation technology.

Claims

1. A process for the catalytic hydrodenitrogenation of quinoline to produce n- propylcyclohexane, characterized in that, The nano functional catalyst is prepared by combining gel method and impregnation method, the catalyst carrier is SAPO-34 doped with sulfonated graphene, proper WO x is introduced as an auxiliary agent, and x%-Ni-y%-Mo-z%-WO x @m%-GO-SAPO-34, x%, y% and z% respectively represent mass fractions of Ni, Mo and W in the catalyst, m% represents the mass fraction of sulfonated graphene in the catalyst, and under the condition that 1,4-dioxane is used as a solvent, quinoline is produced into n-propyl cyclohexane through one-step hydrogenation and denitrification, and the mass fraction of the 1,4-dioxane solution of quinoline is 1-5%.

2. The process for the catalytic hydrogenation of quinoline to n-propylcyclohexane according to claim 1, characterized in that, The catalyst is made of the following components in mass percentage:

3. The process for the catalytic hydrogenation of quinoline to n-propylcyclohexane according to claim 2, characterized in that, The active component Ni is derived from Ni(NO3)2-6H2O and Mo is derived from (NH4)6Mo7O 24 ·4H2O, WO x from the decomposition of ammonium metatungstate.

4. The process for the catalytic hydrodenitrogenation of quinoline to n- propylcyclohexane according to claim 1, characterized in that, The mass fraction of quinoline in the reaction solution is 1-5%.

5. The process for the catalytic hydrodenitrogenation of quinoline to n- propylcyclohexane according to claim 1, characterized in that, Catalyst 2% - Ni - 3% - Mo - 5% - WO x @6% - GO - SAPO - 34 exhibited the best catalytic activity with 99.95% conversion of quinoline and 81.35% selectivity and 81.31% yield of n-propylcyclohexane as the main product. The preferred ratio of Ni:Mo:W is 2%:3%:5%.

6. The method for preparing n-propylcyclohexane by catalytically hydrogenating and denitrifying quinoline according to claim 1 and claim 5, wherein the nanometer catalyst is synthesized by combining gel method and impregnation method, and the reagent dosage and method are controllable.

7. The process for the catalytic hydrogenation of quinoline to n-propylcyclohexane according to claims 1 and 5, characterized in that, The hydrogenation and denitrification reaction temperature of quinoline is 310-410 DEG C, the reaction time is 180 min, and the reaction hydrogen pressure is 4.0 MPa.

8. The method for preparing n-propylcyclohexane by catalytically hydrogenating and denitrifying quinoline according to claim 1 and claim 5, wherein the mass fraction of sulfuric acid sulfonated graphene in the nanometer catalyst is 4-8%.

9. The process for the catalytic hydrogenation of quinoline to n-propylcyclohexane according to claims 1 and 5, characterized in that, Catalyst 2% - Ni - 3% - Mo - 5% - WO x @6% - GO - SAPO - 34 has good stability and can be reused more than 4 times.

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