Process for the production of long chain alkylnaphthalenes
By using segmented regeneration and copper-phosphorus modified catalysts, the problem of complete catalyst regeneration was solved, thereby improving catalyst stability and lifespan, making it suitable for the industrial production of long-chain alkyl naphthalenes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-11-25
- Publication Date
- 2026-05-26
AI Technical Summary
In existing alkylnaphthalene production processes, catalysts are difficult to regenerate completely, resulting in poor catalyst stability and impacting industrial production efficiency and costs.
A segmented regeneration method is adopted, including a first-stage solvent regeneration, a second-stage hydrogen-based regeneration, and a third-stage solvent-hydrogen-based regeneration. Combined with copper and phosphorus modified catalysts, the catalyst activity is restored and carbon deposits are removed through polar solvent flushing and hydrogen saturation treatment.
It achieves complete catalyst regeneration, improves catalyst stability and lifespan, reduces production costs, and is suitable for continuous industrial production.
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Abstract
Description
Technical Field
[0001] This invention relates to the technical field of alkyl naphthalene preparation, and more specifically to a method for producing long-chain alkyl naphthalene. Background Technology
[0002] The alkylation reaction of naphthalene and long-chain olefins is an important commercial chemical reaction. The long-chain alkylnaphthalene produced by the alkylation of naphthalene and long-chain olefins can be used in the production of many important industrial products such as lubricating oils, environmentally friendly rubber oils, high-temperature heat transfer oils, and surfactants.
[0003] Traditional alkylnaphthalene production processes utilize liquid acid catalysts such as HF and AlCl3. These processes have a long history of development, are technologically mature, and highly industrialized; some companies producing alkylnaphthalene still employ these methods. While liquid acid catalysts offer high catalytic activity, allow reactions to proceed at lower temperatures, and are simple to operate, they also suffer from various drawbacks, including environmental pollution, severe equipment corrosion, and difficulties in separating the catalyst from the product. Therefore, there is an urgent need to develop new, green production processes.
[0004] US patent application US5177284A uses ultrastable Y molecular sieve (USY) and β molecular sieve catalysts to synthesize alkyl naphthalenes. However, this method requires a high synthesis temperature and uses an acidic catalyst, resulting in a darker product color, which is not conducive to industrial production.
[0005] US patent application US4604491A uses activated silica-alumina clay as a catalyst to alkylate naphthalene with α-olefins to prepare long-chain alkylnaphthalenes. This method requires a reaction at 200°C for 6 hours, which is too high, results in an excessively long preparation cycle, and is prone to dealkylation. Furthermore, the method uses a large amount of acid-activated silica-alumina clay as a catalyst, increasing industrial production costs and hindering product separation, thus limiting its industrial-scale application.
[0006] Some domestic studies have also been conducted. Guo Haitao et al. reported the preparation of long-chain alkyl naphthalenes using HY molecular sieves. Using C11 and C12 mixed olefins as raw materials and cyclohexane as solvent, the reaction was carried out under the conditions of 1.0 MPa pressure, 130 °C temperature, space velocity of 10 mL / (hg), n(tetradecene):n(naphthalene):n(cyclohexane) = 6:1:60 and reaction time of 6 h. The conversion rate of olefins was 85.22%. However, the conversion rate of this catalyst was low and the preparation cycle was too long.
[0007] Chinese patent application CN1029611C discloses a method for synthesizing alkylnaphthalenes using heteropoly acids or their salts as catalysts. However, this method requires a pressurized, sealed autoclave, placing high demands on the reaction equipment and hindering industrial production. Furthermore, the patent's embodiments only use ethylene as the alkylating agent, thus failing to effectively guide the synthesis of long-chain alkylnaphthalenes.
[0008] Chinese patent application CN10120516A discloses a method for preparing long-chain alkylnaphthalenes using ultrafine silica-supported heteropolyacids as catalysts. However, the preferred reaction temperature is 130-40℃, resulting in a short catalyst lifetime. Furthermore, the use of ultrafine solid catalysts leads to excessive bed pressure drop, which is detrimental to continuous alkylation reactions in slurry beds and industrial production.
[0009] Mengke Wang et al. reported that using HY as a catalyst, under conditions of 1.0 MPa pressure, 175 °C temperature, liquid hourly space velocity (LHSV) of 6.0, and a tetradecene to naphthalene molar ratio of 1.25:1, the conversion of the starting naphthalene was 79%, and the selectivity for monoalkyl naphthalene was 92%. The catalyst exhibited low conversion and product selectivity, with the conversion decreasing rapidly as the reaction proceeded. Improving catalyst stability is a problem that needs to be addressed for molecular sieve catalysts.
[0010] The coking reaction on catalysts begins with the further alkylation of long-chain monoalkylnaphthalenes and long-chain olefins to form dialkylnaphthalenes. Further reactions such as hydrogen transfer, alkylation, and cyclization occur, resulting in non-volatile coke deposits with polycyclic structures. These deposits, known as hard coke, are generally difficult to remove and require high-temperature oxidative roasting to remove them. However, high-temperature roasting of conventional catalysts often damages their structure, thereby impairing their activity and stability.
[0011] Solid acid catalysts are prone to coking and deactivation, requiring frequent regeneration. Regeneration methods for deactivated catalysts generally include hydrogenation regeneration, solvent dissolution and cleaning, high-temperature oxidative roasting, and oxidant cleaning. Among these, hydrogenation regeneration and solvent dissolution and cleaning are relatively easy to implement industrially. However, solvent washing methods often cannot achieve complete catalyst regeneration, only partial regeneration. After several washing and regeneration processes, the catalyst still needs to undergo high-temperature roasting to remove the accumulated hard carbon. This process is cumbersome, costly, and the hard carbon is difficult to remove. Summary of the Invention
[0012] The purpose of this invention is to overcome the problem that existing solvent regeneration techniques cannot achieve complete catalyst regeneration, and to provide a method for producing long-chain alkyl naphthalenes. This method can achieve complete regeneration of deactivated catalysts, improve catalyst stability, and enable long-cycle production of long-chain alkyl naphthalenes.
[0013] To achieve the above objectives, the present invention provides a method for producing long-chain alkylnaphthalene, wherein the method includes: alkylation reaction, regeneration of the spent catalyst, and recycling of the regenerated catalyst;
[0014] The alkylation reaction includes: alkylation of long-chain olefins and naphthalene in the presence of a catalyst and a first solvent. The catalyst includes a molecular sieve, a support, copper, and phosphorus. The amount of medium-strong acid in the catalyst accounts for more than 35% of the total acid amount. The acid content distribution of the catalyst is characterized by the NH3 temperature-programmed desorption method (NH3-TPD), wherein 250℃-450℃ is the medium-strong acid.
[0015] The regeneration of the spent catalyst includes: sequentially performing a first-stage solvent regeneration, a second-stage hydrogen regeneration, and a third-stage solvent hydrogen regeneration on the spent catalyst.
[0016] Preferably, the regeneration of the spent catalyst includes:
[0017] S1. The catalyst to be generated is regenerated in the presence of a second solvent;
[0018] S2. The product obtained in step S1 is subjected to two-stage hydrogen regeneration under hydrogen-exposed conditions.
[0019] S3. The product obtained in step S2 is subjected to three-stage solvent hydrogen regeneration under hydrogen-exposed conditions and in the presence of a second solvent to obtain a regenerated catalyst.
[0020] The method provided by this invention selects a catalyst with specific medium-strong acid. The introduction of copper can increase the proportion of medium-strong acid in the catalyst, reduce the proportion of strong acid, reduce the occurrence of side reactions, and improve the catalyst life. Furthermore, synergistic phosphorus modification can improve the hydrothermal stability of the catalyst under high temperature conditions without negatively affecting the acidity and stability of the catalyst itself. This enables the catalyst to operate continuously for a long period of time, which is beneficial to continuous industrial production and greatly saves production costs.
[0021] The inventors of this invention discovered that high-temperature calcination negatively impacts the P and Cu sites on phosphorus- and copper-modified catalysts. Repeated high-temperature calcination leads to the escape of P from the catalyst, while Cu sites undergo agglomeration, affecting the catalyst's subsequent activity and hydrothermal stability. The method provided by this invention, preferably, involves controlling the order of raw material addition during catalyst preparation. Specifically, the molecular sieve and support are mixed first, and then directly mixed with a solution containing a copper precursor and a phosphorus-containing compound without calcination to form the catalyst. This method requires only one calcination during catalyst preparation, avoiding the multiple calcinations required for modification after catalyst formation in existing technologies, thus reducing the complexity of the catalyst preparation process and lowering energy consumption.
[0022] The method provided by this invention uses copper and phosphorus in combination to prepare the catalyst, which can improve the catalyst stability and target product selectivity, promote the formation of monoalkyl naphthalene in the main reaction, inhibit the further alkylation of monoalkyl naphthalene to dialkyl naphthalene, inhibit carbon deposition, and extend the catalyst life.
[0023] The method provided by this invention can achieve complete regeneration of deactivated catalysts through staged regeneration. In this invention, the deactivated catalyst is first rinsed with a highly polar solvent to remove reactants and macromolecular products adsorbed on acidic sites, restoring some of the catalyst's activity. Then, the catalyst undergoes a two-stage hydrogen-induced regeneration. The hard carbon on the catalyst is hydrogen-saturated using hydrogen gas, causing the carbon deposits on the catalyst to hydrogenate into smaller molecules. Then, solvent washing regeneration is performed under hydrogen-induced conditions to saturate the macromolecular carbon deposit precursors generated during the reaction. The carbon deposits are then dissolved using the principle of "like dissolves like" in the solvent. This effectively removes macromolecular substances such as carbon deposit precursors generated during the reaction, avoiding the formation of hard carbon, thereby improving catalyst stability and enabling the continuous production of long-chain alkyl naphthalenes. Detailed Implementation
[0024] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0025] This invention provides a method for producing long-chain alkylnaphthalene, wherein the method includes: alkylation reaction, regeneration of the spent catalyst, and recycling of the regenerated catalyst;
[0026] The alkylation reaction includes: alkylation of long-chain olefins and naphthalene in the presence of a catalyst and a first solvent. The catalyst includes a molecular sieve, a support, copper, and phosphorus. The amount of medium-strong acid in the catalyst accounts for more than 35% of the total acid amount. The acid content distribution of the catalyst is characterized by the NH3 temperature-programmed desorption method (NH3-TPD), wherein 250℃-450℃ is the medium-strong acid.
[0027] The regeneration of the spent catalyst includes: sequentially performing a first-stage solvent regeneration, a second-stage hydrogen regeneration, and a third-stage solvent hydrogen regeneration on the spent catalyst.
[0028] The method provided by this invention selects a catalyst with a specific proportion of medium-strong acids. The introduction of copper can increase the proportion of medium-strong acids and decrease the proportion of strong acids in the catalyst, thereby reducing the occurrence of side reactions and increasing the catalyst's lifespan. Furthermore, synergistic phosphorus modification can improve the hydrothermal stability of the catalyst under high-temperature conditions without negatively affecting the acidity and stability of the catalyst itself. This enables the catalyst to operate continuously for a long period, which is beneficial for continuous industrial production and greatly saves production costs.
[0029] The method provided by this invention uses copper and phosphorus in combination to prepare the catalyst, which can improve the catalyst stability and target product selectivity, promote the formation of monoalkyl naphthalene in the main reaction, inhibit the further alkylation of monoalkyl naphthalene to dialkyl naphthalene, inhibit carbon deposition, and extend the catalyst life.
[0030] The method provided by this invention can achieve complete regeneration of deactivated catalysts through staged regeneration. In this invention, the deactivated catalyst is first rinsed with a highly polar solvent to remove reactants and macromolecular products adsorbed on acidic sites, restoring some of the catalyst's activity. Then, the catalyst undergoes a two-stage hydrogen-induced regeneration. The hard carbon on the catalyst is hydrogen-saturated using hydrogen gas, causing the carbon deposits on the catalyst to hydrogenate into smaller molecules. Then, solvent washing regeneration is performed under hydrogen-induced conditions to saturate the macromolecular carbon deposit precursors generated during the reaction. The carbon deposits are then dissolved using the principle of "like dissolves like" in the solvent. This effectively removes macromolecular substances such as carbon deposit precursors generated during the reaction, avoiding the formation of hard carbon, thereby improving catalyst stability and enabling the continuous production of long-chain alkyl naphthalenes.
[0031] In this invention, the acid content distribution of the catalyst was characterized using the NH3 temperature-programmed desorption method (NH3-TPD). The characterization method is as follows: Instrument: Quantachrome Chemstar TPx; Testing procedure: 0.15 g (20-40 mesh) of molecular sieve or catalyst sample was weighed, heated to 550 °C to dry, and then cooled to 100 °C to saturate the catalyst with NH3 adsorption. The temperature was then raised to 250 °C, 350 °C, 450 °C, and 550 °C to desorb NH3, and the NH3 concentration was detected using a TCD detector. The adsorption curves obtained at different temperature ranges were integrated, and the instrument automatically calculated the acid density distribution at different temperatures. The acid content obtained at 250 °C was identified as weak acid, 250 °C-450 °C as moderately strong acid, and 450 °C-550 °C as strong acid.
[0032] In this invention, preferably, the amount of medium-strong acid in the catalyst accounts for 40-50% of the total acid amount, more preferably 42-45%, wherein the acid content distribution of the catalyst is characterized by the NH3 temperature programmed desorption method (NH3-TPD), wherein 250℃-450℃ is the medium-strong acid.
[0033] In this invention, the type of molecular sieve is not particularly limited. Preferably, the molecular sieve is selected from at least one of Y-type molecular sieve, ZSM-5 type molecular sieve, β-type molecular sieve, MCM-22 type molecular sieve and mordenite, more preferably at least one of Y-type molecular sieve, ZSM-5 type molecular sieve and β-type molecular sieve, and even more preferably β-type molecular sieve.
[0034] In this invention, preferably, the silicon-aluminum molar ratio of the molecular sieve is 2-1000:1, and more preferably 2-100:1.
[0035] In this invention, a wide range of carrier types can be selected. Preferably, the carrier is alumina and / or silicon oxide.
[0036] In this invention, the content of molecular sieve and support in the catalyst is calculated based on the amount of feed.
[0037] In this invention, the copper and phosphorus contents in the catalyst were determined by X-ray fluorescence (XRF) under the following conditions: tungsten target (excitation voltage 40 kV, excitation current 250 mA). The sample powder was pressed into tablets, with an applied pressure typically of 500-1000 kPa. The relationship between the fluorescence wavelength and the atomic number Z of the element follows Moseley's law: λ = K(ZS). -2 Based on this, qualitative analysis of elements is performed by measuring fluorescence wavelengths. Semi-quantitative analysis of elements is performed by utilizing the relationship that the intensity of each element's fluorescence rays is proportional to its concentration.
[0038] In this invention, the preparation method of the catalyst is not particularly limited. Preferably, the preparation method of the catalyst includes:
[0039] (1) Mix the molecular sieve and the support to obtain a mixture;
[0040] (2) The mixture obtained in step (1) is mixed with a solution containing copper precursor and phosphorus compound and then calcined once to obtain a catalyst.
[0041] By adopting the above preparation method, the proportion of medium-strong acids in the catalyst is increased by introducing copper and the proportion of strong acids is decreased. This reduces the adsorption of highly polar long-chain olefins at acidic sites, reduces the occurrence of side reactions, and improves the catalyst lifetime. Furthermore, synergistic phosphorus modification improves the hydrothermal stability of the catalyst under high-temperature conditions without negatively affecting the acidity and stability of the catalyst itself. This enables the catalyst to operate continuously for a long period, which is beneficial for continuous industrial production and greatly saves production costs.
[0042] By adopting the above preparation method, and by controlling the order of adding raw materials during the catalyst preparation process, strictly following the procedure of first mixing the molecular sieve and the support, and then directly mixing them with a solution containing copper precursors and phosphorus compounds without calcination, the catalyst can be prepared by only one calcination during the catalyst preparation process. This avoids the multiple calcinations required for modification after catalyst formation in the prior art, reduces the difficulty of the catalyst preparation process, and reduces energy consumption.
[0043] In this invention, the types of molecular sieves and supports in step (1) have been described above and will not be repeated here.
[0044] In this invention, the range of selectable amounts of molecular sieve and support is relatively wide. Preferably, the amounts of molecular sieve and support are such that, in the prepared catalyst, the mass ratio of molecular sieve to support, based on oxides, is 95:5-20:80, more preferably 90:10-25:75.
[0045] In this invention, preferably, in step (1), the support exists in a solid and / or sol state, more preferably in a sol state. The advantage of this preferred embodiment is that the molecular sieve and support can mix better, be more uniformly distributed, have stronger interactions, and exhibit better catalyst activity.
[0046] In this invention, preferably, when the carrier exists in a sol state, the carrier is provided by aluminum sol and / or silica sol.
[0047] In this invention, there is no particular limitation on the concentration of aluminum sol and silica sol. Preferably, the concentration of each of the aluminum sol and silica sol is independently 10-30 wt%.
[0048] In this invention, preferably, in step (1), the carrier is aluminum oxide.
[0049] In this invention, there is no particular limitation on the type of alumina precursor, as long as it can provide alumina. Preferably, the alumina is provided by at least one of boehmite, aluminum chloride, aluminum hydroxide, and aluminum sol.
[0050] In this invention, there is no particular limitation on the type of copper precursor, as long as copper can be provided. Preferably, in step (2), the copper precursor is selected from copper-soluble compounds, and more preferably from at least one of copper chloride, cuprous chloride, copper nitrate, copper sulfate, and cuprous sulfate.
[0051] In this invention, there is no particular limitation on the amount of copper precursor used. Preferably, the amount of copper precursor used is such that the mass ratio of the support (calculated as oxide) to the copper (calculated as element) in the prepared catalyst is 80:20-99.9:0.1, more preferably 85:15-99:1. The advantage of this preferred embodiment is that the preparation method is simple, and Cu... 2+ / Cu + More of it is distributed on the molecular sieve.
[0052] In this invention, there is no particular limitation on the type of phosphorus-containing compound, as long as it can provide phosphorus. Preferably, in step (2), the phosphorus-containing compound is selected from at least one of phosphoric acid, phosphorous acid, soluble phosphate, and phosphite.
[0053] In this invention, there is no particular limitation on the specific type of soluble phosphate. Preferably, the soluble phosphate is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate.
[0054] In this invention, preferably, the phosphorus-containing compound is provided by an aqueous solution of a phosphorus-containing compound. Preferably, the concentration of the phosphorus-containing compound is 0.01-25 wt%, more preferably 5-25 wt%.
[0055] In this invention, there is no particular limitation on the amount of phosphorus-containing compound used. Preferably, the amount of phosphorus-containing compound used is such that, in the prepared catalyst, the mass ratio of copper to phosphorus, by elemental basis, is 5:95-98:2, more preferably 30:70-80:20. By controlling the amounts of copper precursor and phosphorus-containing compound, it is possible to control the acid distribution in the catalyst, increase the proportion of moderately strong acids, and improve the hydrothermal stability of the catalyst, enabling long-term continuous operation of the catalyst, which is beneficial for industrial production.
[0056] In this invention, when the alumina support exists in a sol state, a pectin is introduced to dissolve it. This invention does not specifically limit the specific method of pectin dissolution; those skilled in the art can choose according to actual needs. Preferably, the catalyst preparation method further includes: introducing a pectin into a solution containing a copper precursor and a phosphorus-containing compound, and mixing it with the mixture obtained in step (1) to form a precipitate.
[0057] In this invention, there is no particular limitation on the type of adhesive solvent; adhesive solvents conventionally defined in the art are applicable to this invention. Preferably, the adhesive solvent is selected from at least one of nitric acid, hydrochloric acid, sulfuric acid, formic acid, and acetic acid.
[0058] In this invention, there is no particular limitation on the amount of peptizing solvent used, as long as it meets the peptizing requirements. Those skilled in the art can select the appropriate amount based on actual needs. Preferably, the amount of peptizing solvent is such that the pH of the solution containing the copper precursor and the phosphorus-containing compound is 1-4. Similarly, this invention does not particularly limit the concentration of the peptizing solvent; those skilled in the art can select the appropriate concentration based on actual needs.
[0059] In this invention, there are no particular limitations on the molding method in step (2), and those skilled in the art can choose according to actual needs.
[0060] In this invention, the range of roasting conditions is relatively wide. Preferably, in step (2), the roasting conditions include: a temperature of 450-800℃ and a time of 1-15h; more preferably, in step (2), the roasting conditions include: a temperature of 500-700℃ and a time of 2-8h.
[0061] In this invention, preferably, the long-chain olefin is selected from olefins of C6-24, and more preferably from at least one of C8, C10, C12, C14, C16, and C18, for example, it can be n-octene, n-hexadecene, or n-tetracosene.
[0062] In this invention, preferably, the first solvent is selected from at least one of ethanol, ethylene glycol, cyclohexane and glycerol, and more preferably cyclohexane.
[0063] In this invention, there is no particular limitation on the amount of reactants used. Preferably, the molar ratio of the long-chain olefin to naphthalene is 1-10:1, more preferably 2-9:1.
[0064] In this invention, preferably, the molar ratio of the first solvent to naphthalene is 5-250:1, more preferably 10-200:1.
[0065] In this invention, the selection range of alkylation reaction conditions is relatively wide. Preferably, the alkylation reaction conditions include: a reaction temperature of 80-280℃, more preferably 100-240℃; a reaction pressure of 0.5-8 MPa, more preferably 1-5 MPa; and a mass hourly space velocity (HHSV) of 0.01-20 h⁻¹ for the long-chain olefin and naphthalene. -1 Preferably 1-10h -1 .
[0066] In this invention, preferably, the reaction is a liquid-phase reaction and / or a gas-phase reaction, and more preferably a liquid-phase reaction.
[0067] In this invention, it should be noted that the liquid-phase reaction refers to the feeding of both the long-chain olefins and naphthalenes in liquid phase or the reaction conditions during the reaction process that allow the long-chain olefins and naphthalenes to be in a liquid phase state. This invention does not have any particular limitation on the gasification method of the raw materials, and methods conventionally defined in the art can be applied to this invention.
[0068] In this invention, preferably, the catalyst is obtained when the total acid content of the catalyst is reduced to below 40% during the alkylation reaction.
[0069] The inventors of this invention discovered that complete regeneration of deactivated catalysts can be achieved through staged regeneration. In this invention, the deactivated catalyst is first rinsed with a highly polar solvent to remove reactants and macromolecular products adsorbed on acidic sites, restoring some of the catalyst's activity. Then, the catalyst undergoes a two-stage hydrogen-induced regeneration. Hydrogen saturation is used to hydrogen-saturate the hard carbon on the catalyst, causing the carbon deposits to decompose into smaller molecules. Next, solvent washing and regeneration are performed under hydrogen-induced conditions to saturate the macromolecular carbon deposit precursors generated during the reaction. The carbon deposits are then dissolved using the principle of "like dissolves like" in the solvent. This effectively removes macromolecular substances such as carbon deposit precursors generated during the reaction, preventing the formation of hard carbon, improving catalyst stability, and enabling the continuous production of long-chain alkyl naphthalenes.
[0070] In this invention, solvent regeneration is performed in three stages. Through the close coordination of each step, complete regeneration of the spent catalyst is achieved, thereby improving the catalyst's lifespan. Preferably, the solvent regeneration of the spent catalyst includes:
[0071] S1. The catalyst to be generated is regenerated in the presence of a second solvent;
[0072] S2. The product obtained in step S1 is subjected to two-stage hydrogen regeneration under hydrogen-exposed conditions.
[0073] S3. The product obtained in step S2 is subjected to three-stage solvent hydrogen regeneration under hydrogen-exposed conditions and in the presence of a second solvent to obtain a regenerated catalyst.
[0074] This invention first uses a highly polar secondary solvent to wash away the deactivated catalyst, removing reactants and macromolecular products adsorbed on acidic sites and restoring some of the catalyst's activity. Then, the catalyst is saturated with hydrogen, and the hard carbon on the catalyst is hydrogen-saturated with metallic copper, causing the carbon deposits on the catalyst to decompose into smaller molecules. Next, solvent washing and regeneration are performed under hydrogen-containing conditions. After saturating the large molecular carbon deposit precursors generated during the reaction with hydrogen, the carbon deposits are dissolved using the "like dissolves like" mechanism of the solvent. This effectively removes the large molecular substances such as carbon deposit precursors generated during the reaction, preventing the formation of hard carbon and completely deactivating the catalyst.
[0075] In this invention, preferably, in step S1, the recovery rate of the medium-strong acid content of the product obtained in step S1 reaches 80-95%. The advantage of this preferred embodiment is that the method is simple and can effectively restore the acid content of the catalyst.
[0076] It should be noted that the recovery rate here refers to the recovery rate of acid content in the regenerated catalyst compared to the fresh catalyst after solvent regeneration, which is calculated using the following formula:
[0077] Recovery rate (%) = Acidity of the catalyst to be regenerated after solvent regeneration / Acidity of the fresh catalyst * 100.
[0078] In this invention, a first solvent is used to perform a solvent regeneration of the catalytic catalyst. This invention allows for a wide range of choices for the first solvent. Preferably, in step S1, the second solvent is selected from at least one of ethanol, ethylene glycol, and glycerol, more preferably ethylene glycol and / or glycerol. The catalytic catalyst is washed with alcohol to remove reactants and macromolecular products adsorbed on acidic sites, restoring some of the catalyst's activity.
[0079] In this invention, the selection range for the conditions of the first-stage solvent regeneration is relatively wide. Preferably, in step S1, the conditions for the first-stage solvent regeneration include: a temperature of 220-400℃, a time of 0.5-24h, and a volume hourly space velocity (VHSV) of the second solvent of 0.01-20h. -1 Further preferably, in step S1, the conditions for the first-stage solvent regeneration include: a temperature of 250-350℃, a time of 2-12 h, and a volume hourly space velocity (VHSV) of 0.5-15 h⁻¹ for the second solvent. -1 .
[0080] In this invention, the selection range for the two-stage hydrogen regeneration conditions is relatively wide. Preferably, in step S2, the conditions for the two-stage hydrogen regeneration include: a temperature of 250-400℃, a time of 0.5-24h, a pressure of 0.01-10MPa, and a hydrogen flow rate of 0.001-10000mL / min relative to 1g of fresh catalyst; preferably, in step S2, the conditions for the two-stage hydrogen regeneration include: a temperature of 260-350℃, a time of 2-20h, a pressure of 0.1-8MPa, and a hydrogen flow rate of 10-800mL / min relative to 1g of fresh catalyst. In this invention, the introduction of hydrogen saturates the unsaturated hydrocarbons in the catalyst, converting hard carbon into soft carbon, thereby further achieving complete catalyst regeneration.
[0081] In this invention, preferably, the third solvent is selected from at least one of C6-C12 n-alkanes, alcohols and benzene, and more preferably from C6-C12 n-alkanes; more preferably, the C6-C12 n-alkanes are selected from at least one of n-hexane, n-heptane, n-octane and n-decane.
[0082] In this invention, preferably, the temperature of the three-stage solvent hydrogen regeneration is 10-100°C higher than the temperature of the two-stage hydrogen regeneration.
[0083] In this invention, solvent washing and regeneration under hydrogen-exposed conditions can saturate the macromolecular carbon deposit precursors generated during the reaction with hydrogen, and then dissolve the carbon deposits using the "like dissolves like" mechanism of the solvent. This effectively removes macromolecular substances such as carbon deposit precursors generated during the reaction, avoids the formation of hard carbon, and prevents complete deactivation of the catalyst. Preferably, in step S3, the conditions for the three-stage solvent hydrogen-exposed regeneration include: a temperature of 260-500℃, a time of 0.5-50 h, a pressure of 0.01-10 MPa, and a volume hourly space velocity (VHSV) of 0.01-15 h⁻¹ for the third solvent. -1 Further preferably, in step S3, the conditions for the three-stage solvent regeneration under hydrogen include: a temperature of 270-450℃, a time of 1-48h, a pressure of 0.1-8MPa, and a volume hourly space velocity (VHSV) of 0.1-10h for the third solvent. -1 .
[0084] The present invention will be described in detail below through examples. Unless otherwise specified, all raw materials used in the following preparation examples and embodiments are commercially available products.
[0085] In this invention, the acid content distribution of the catalyst was characterized using the NH3 temperature-programmed desorption method (NH3-TPD). The characterization method is as follows: Instrument: Quantachrome Chemstar TPx; Testing procedure: 0.15 g (2040 mesh) of molecular sieve or catalyst sample was weighed, heated to 550 °C to dry, and then cooled to 100 °C to saturate the catalyst with NH3 adsorption. The temperature was then raised to 250 °C, 350 °C, 450 °C, and 550 °C to desorb NH3, and the NH3 concentration was detected using a TCD detector. The adsorption curves obtained at different temperature ranges were integrated, and the instrument automatically calculated the acid density distribution at different temperatures. The acid content obtained at 250 °C was identified as weak acid, 250 °C-450 °C as moderately strong acid, and 450 °C-550 °C as strong acid.
[0086] The preparation examples and comparative examples are used to illustrate the preparation of catalysts.
[0087] Preparation Example 1
[0088] (1) 90g of HY molecular sieve (silicon-aluminum molar ratio of 5) and 10g of alumina are mixed evenly;
[0089] (2) Take 3g of cuprous chloride and add it to 100g of H3PO4 solution with a concentration of 10wt%. Add it to the mixed powder in step (1) and mix evenly. Then, use an extruder to roll and extrude the mixture into shape. Calcine at 500℃ for 12h to obtain catalyst Y-1. The acid content of the catalyst is shown in Table 1.
[0090] Preparation Example 2
[0091] (1) 750g of β molecular sieve (silicon-aluminum molar ratio of 20) and 1250g of aluminum sol with a concentration of 20wt% were mixed evenly;
[0092] (2) Take 5g of Cu2SO4 and add it to 100g of KH2PO4 solution with a concentration of 5wt%. Then, adjust the pH to 2.5 with nitric acid and add it to the mixture of molecular sieve and aluminum sol. After mixing and grinding, extrude it into small balls and then calcine at 600℃ for 1h to obtain catalyst β-1. The acidity of the catalyst is shown in Table 1.
[0093] Preparation Example 3
[0094] (1) 200g of ZSM-5 molecular sieve (silicon-aluminum molar ratio of 50) and 500g of silica sol with a concentration of 20wt% were mixed evenly;
[0095] (2) Take 10g of Cu(NO3)2 and add it to 100g of K3PO4 solution with a concentration of 10wt%. Add it to the mixture of molecular sieve and silica sol, mix evenly, and then extrude it into shape using an extruder. Calcine it at 800℃ for 2h to obtain catalyst ZSM-1. The acid content of the catalyst is shown in Table 1.
[0096] Preparation Example 4
[0097] The catalyst was prepared according to the method of Preparation Example 2, except that 50g of Cu2SO4 was added to 200g of KH2PO4 solution with a concentration of 25wt%, and then the pH was adjusted to 4 with nitric acid before being added to a mixture of molecular sieve and aluminum sol. The mixture was then calcined at 500°C for 8 hours to obtain catalyst β-2.
[0098] The acidity results of the catalyst are shown in Table 1.
[0099] Preparation Example 5
[0100] The catalyst was prepared according to the method of Preparation Example 2, except that the amount of Cu2SO4 added was 60g, and other conditions remained unchanged, to obtain catalyst β-3.
[0101] The acidity results of the catalyst are shown in Table 1.
[0102] Preparation Example 6
[0103] The catalyst was prepared according to the method of Preparation Example 2, except that 2g of Cu2SO4 was added to 200g of KH2PO4 solution with a concentration of 25wt% to obtain catalyst β-4.
[0104] The acidity results of the catalyst are shown in Table 1.
[0105] Preparation Example 7
[0106] The catalyst was prepared according to the method of Preparation Example 2, except that alumina powder was used instead of alumina sol, while other conditions remained unchanged, to obtain catalyst β-5. The acidity results of the catalyst are shown in Table 1.
[0107] Comparative Preparation Example 1
[0108] The catalyst was prepared according to the method of Preparation Example 1, except that subsequent phosphorus loading was not performed, and the other conditions were the same as in Preparation Example 1, to obtain catalyst DY-1.
[0109] The acidity results of the catalyst are shown in Table 1.
[0110] Comparative Preparation Example 2
[0111] The catalyst was prepared according to the method of Preparation Example 1, except that only phosphoric acid solution was added during catalyst preparation, and the other conditions were the same as in Preparation Example 1, resulting in catalyst DY-2.
[0112] The acidity results of the catalyst are shown in Table 1.
[0113] Comparative preparation example 3
[0114] The catalyst was prepared according to the method of Preparation Example 2, except that only a copper salt solution was added during catalyst preparation, and the other conditions were the same as in Preparation Example 2, to obtain catalyst Dβ-1.
[0115] The acidity results of the catalyst are shown in Table 1.
[0116] Comparative preparation example 4
[0117] The catalyst was prepared according to the method of Preparation Example 2, except that only phosphoric acid solution was added during catalyst preparation, while the other conditions were the same as in Preparation Example 2, resulting in catalyst Dβ-2. The acidity of the catalyst is shown in Table 1.
[0118] Table 1
[0119]
[0120]
[0121] The examples and comparative examples are used to illustrate the production of long-chain alkyl naphthalenes.
[0122] Examples 1-7
[0123] The catalysts from Preparation Examples 1-7 were used as fresh catalysts for the synthesis of long-chain alkyl naphthalenes. The catalysts were loaded into a fixed-bed reactor, the reaction temperature was 100°C, the reaction pressure was 1 MPa, the ratio of nnaphthalene:n-octene:ncyclohexane was 2:1:10, and the mass hourly space velocity (WHSV) of naphthalene and n-octene was 10 h⁻¹. -1When the total acid content of the catalyst reaches below 40% during the reaction, the catalyst is considered deactivated, and a new catalyst is obtained. The reaction feed is stopped, and the new catalyst is washed with glycerol at 250°C for 2 hours, with a glycerol volume hourly space velocity of 0.5 h⁻¹. -1 .
[0124] After glycerol flushing, the feed was stopped, and the catalyst was subjected to hydrogen saturation at 260°C for 2 hours at a pressure of 0.1 MPa. The hydrogen flow rate was 10 mL / min relative to 1 g of fresh catalyst.
[0125] After hydrogen saturation, the temperature was raised to 270℃, and the catalyst was purged again with n-hexane for 1 hour under a hydrogen atmosphere at a pressure of 0.1 MPa and a hexane volume hourly space velocity of 0.1 h⁻¹. -1 .
[0126] After washing, the raw materials were fed back in for reaction, and the reaction results are shown in Table 2.
[0127] Example 8
[0128] The catalyst from Preparation Example 2 was used as the fresh catalyst. The catalyst was loaded into a fixed-bed reactor, the reaction temperature was 200°C, the reaction pressure was 3 MPa, the ratio of nnaphthalene:n-hexadecene:ncyclohexane was 6:1:60, and the mass hourly space velocity (WHSV) of naphthalene and n-hexadecene was 3 h⁻¹. -1 When the total acid content of the fresh catalyst falls below 40% during the reaction, the catalyst is considered deactivated, and a new catalyst is obtained. The reaction feed is stopped, and the catalyst is washed with ethylene glycol at 310°C for 6 hours at a volume hourly space velocity (VHSV) of 5 h⁻¹. -1 .
[0129] After ethylene glycol flushing, the feed was stopped, and the catalyst was subjected to hydrogen saturation at 320℃ for 12 hours at a pressure of 4 MPa. The hydrogen flow rate was 100 mL / min relative to 1 g of fresh catalyst.
[0130] After hydrogen saturation, the temperature was raised to 360℃, and the catalyst was purged again with n-octane for 10 hours under a hydrogen atmosphere at a pressure of 4 MPa and a n-octane volume hourly space velocity of 3 h⁻¹. -1 .
[0131] After washing, the raw materials were fed back in for reaction, and the reaction results are shown in Table 2.
[0132] Example 9
[0133] The catalyst from Preparation Example 2 was used as the fresh catalyst. The catalyst was loaded into a fixed-bed reactor, the reaction temperature was 240°C, the reaction pressure was 5 MPa, the ratio of n-naphthalene:n-tetradecene:n-cyclohexane was 8:1:200, and the mass hourly space velocity (WHSV) of naphthalene and n-tetradecene was 1 h⁻¹. -1When the acid content of the fresh catalyst decreases to below 40% of its original value during the reaction, the catalyst is considered deactivated, and a new catalyst is obtained. The reaction feed is then stopped, and the catalyst is washed with glycerol at 350°C for 12 hours at a volume hourly space velocity (VHSV) of 15 h⁻¹. -1 .
[0134] After glycerol flushing, the feed was stopped, and the catalyst was subjected to hydrogen saturation at 350°C for 20 hours at a pressure of 8 MPa. The hydrogen flow rate was 500 mL / min relative to 1 g of fresh catalyst.
[0135] After hydrogen saturation, the temperature was raised to 450℃, and the catalyst was purged again with n-decane for 48 hours under a hydrogen atmosphere at a pressure of 8 MPa and a n-decane volume hourly space velocity of 10 h⁻¹. -1 .
[0136] After washing, the raw materials were fed back in for reaction, and the reaction results are shown in Table 2.
[0137] Example 10
[0138] The catalyst from Preparation Example 2 was used as the fresh catalyst. The catalyst was loaded into a fixed-bed reactor, the reaction temperature was 100°C, the reaction pressure was 1 MPa, the ratio of nnaphthalene:n-octene:ncyclohexane was 2:1:10, and the mass hourly space velocity (WHSV) of naphthalene and n-octene was 10 h⁻¹. -1 When the acid content of the fresh catalyst decreases to below 40% of its original value during the reaction process, the catalyst is considered deactivated, and a new catalyst is obtained. The reaction feed is then stopped, and the catalyst is washed with glycerol at 240°C for 1 hour, with a glycerol volume hourly space velocity of 0.4 h⁻¹. -1 .
[0139] After glycerol flushing, the feed was stopped, and the catalyst was subjected to hydrogen saturation at 250°C for 1.5 h at a pressure of 0.05 MPa. The hydrogen flow rate was 8 mL / min relative to 1 g of fresh catalyst.
[0140] After hydrogen saturation, the temperature was raised to 260℃, and the catalyst was purged again with n-hexane for 0.8 h under a hydrogen atmosphere at a pressure of 0.05 MPa and a hexane volume hourly space velocity of 0.08 h⁻¹. -1 .
[0141] After washing, the raw materials were fed back in for reaction, and the reaction results are shown in Table 2.
[0142] Comparative Examples 1-4
[0143] Using the catalysts from the comparative preparation examples 1-4 described above, the synthesis and washing / regeneration of long-chain alkylnaphthalenes were carried out according to the method described in Example 1. The reaction results are shown in Table 2.
[0144] Comparative Example 5
[0145] The catalyst from Preparation Example 2 was used as a fresh catalyst and loaded into a fixed-bed reactor. The reaction temperature was 100°C, the reaction pressure was 1 MPa, the ratio of nnaphthalene:n-octene:ncyclohexane was 2:1:10, and the mass hourly space velocity (WHSV) of naphthalene and n-octene was 10 h⁻¹. -1 The catalyst is considered deactivated when the acid content decreases to below 40% of that of the fresh catalyst, yielding a spent catalyst. The reaction feed is then stopped, and the catalyst is flushed with glycerol at 250°C for 2 hours at a volume hourly space velocity (VHSV) of 0.5 h⁻¹. -1 .
[0146] The catalyst was heated to 270℃ and then flushed again with n-hexane for 1 hour at a pressure of 0.1 MPa and a hexane volume hourly space velocity of 0.1 h⁻¹. -1 .
[0147] After washing, the raw materials were fed back in for reaction, and the reaction results are shown in Table 2.
[0148] Comparative Example 6
[0149] The catalyst from Preparation Example 2 was used as a fresh catalyst and loaded into a fixed-bed reactor. The reaction temperature was 100°C, the reaction pressure was 1 MPa, the ratio of nnaphthalene:n-octene:ncyclohexane was 2:1:10, and the mass hourly space velocity (WHSV) of naphthalene and n-octene was 10 h⁻¹. -1 When the catalyst acid content decreases to less than 40% of that of the fresh catalyst, the catalyst is considered deactivated, and a new catalyst is obtained. The reaction feed is then stopped.
[0150] Solvent washing and regeneration were performed using the method described in CN 111589434 A, and the reaction results are shown in Table 2.
[0151] Table 2
[0152]
[0153] As shown in the table above, the washing and regeneration method of the present invention effectively regenerates the catalyst to be regenerated, and after several reaction-regeneration cycles, the catalyst life does not change significantly. In contrast, the comparative method cannot effectively regenerate the catalyst completely, and the catalyst life is significantly reduced after regeneration.
[0154] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for producing long-chain alkyl naphthalene, wherein, The method includes: alkylation reaction, regeneration of the spent catalyst, and recycling of the regenerated catalyst; The alkylation reaction includes: alkylation of long-chain olefins and naphthalene in the presence of a catalyst and a first solvent. The catalyst includes a molecular sieve, a support, copper, and phosphorus. The amount of medium-strong acid in the catalyst accounts for more than 35% of the total acid amount. The acid content distribution of the catalyst is characterized by the NH3 temperature-programmed desorption method (NH3-TPD), wherein 250℃-450℃ is the medium-strong acid. The regeneration of the spent catalyst includes: sequentially performing a first-stage solvent regeneration, a second-stage hydrogen regeneration, and a third-stage solvent hydrogen regeneration on the spent catalyst.
2. The method according to claim 1, wherein, The catalyst contains 40-50% medium-strong acid, more preferably 42-45% of the total acid content. The acid content distribution of the catalyst is characterized by the NH3-TPD method, wherein 250℃-450℃ is the medium-strong acid.
3. The method according to claim 1 or 2, wherein, The molecular sieve is selected from at least one of Y-type molecular sieve, ZSM-5 type molecular sieve, β-type molecular sieve, MCM-22 type molecular sieve and mordenite, preferably at least one of Y-type molecular sieve, ZSM-5 type molecular sieve and β-type molecular sieve, and more preferably β-type molecular sieve; Preferably, the carrier is alumina and / or silicon oxide.
4. The method according to any one of claims 1-3, wherein, The mass ratio of the molecular sieve to the support, based on oxides, is 95:5-20:80, more preferably 90:10-25:75; Preferably, the mass ratio of copper to phosphorus is 5:95-98:2, more preferably 30:70-80:20, based on elemental composition. Preferably, the mass ratio of the carrier (calculated as oxide) to the copper (calculated as element) is 80:20-99.9:0.1, more preferably 85:15-99:
1.
5. The method according to any one of claims 1-4, wherein, The method for preparing the catalyst includes: (1) Mix the molecular sieve and the support to obtain a mixture; (2) The mixture obtained in step (1) is mixed with a solution containing copper precursor and phosphorus compound and then calcined once to obtain a catalyst.
6. The method according to claim 5, wherein, In step (1), the carrier exists in a solid and / or sol state, more preferably in a sol state; Preferably, in step (2), the copper precursor is selected from copper-soluble compounds, and more preferably from at least one of copper chloride, cuprous chloride, copper nitrate, copper sulfate, and cuprous sulfate; Preferably, in step (2), the phosphorus-containing compound is selected from at least one of phosphoric acid, phosphorous acid, soluble phosphate, and phosphite; Preferably, the soluble phosphate is selected from at least one of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate.
7. The method according to claim 5, wherein, The method for preparing the catalyst further includes: introducing a peptide solvent into a solution containing a copper precursor and a phosphorus-containing compound and mixing it with the mixture obtained in step (1) to form a shape; Preferably, the adhesive solvent is selected from at least one of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, and acetic acid; Preferably, the amount of the adhesive solvent is such that the pH of the solution containing the copper precursor and the phosphorus-containing compound is 1-4.
8. The method according to claim 5, wherein, In step (2), the calcination conditions include: a temperature of 450-800℃ and a time of 1-15h; Preferably, in step (2), the roasting conditions include: a temperature of 500-700℃ and a time of 2-8h.
9. The method according to any one of claims 1-8, wherein, The long-chain olefin is selected from C6-24 olefins, preferably selected from at least one of C8 olefins, C10 olefins, C12 olefins, C14 olefins, C16 olefins and C18 olefins; Preferably, the first solvent is selected from at least one of ethanol, ethylene glycol, cyclohexane, and glycerol, and more preferably cyclohexane; Preferably, the molar ratio of the long-chain olefin to naphthalene is 1-10:1, more preferably 2-9:1; Preferably, the molar ratio of the first solvent to naphthalene is 5-250:1, more preferably 10-200:1; Preferably, the alkylation reaction conditions include: a reaction temperature of 80-280℃, preferably 100-240℃; a reaction pressure of 0.5-8 MPa, preferably 1-5 MPa; and a mass hourly space velocity (HHSV) of 0.01-20 h⁻¹ for the long-chain olefin and naphthalene. -1 Preferably 1-10h -1 .
10. The method according to any one of claims 1-9, wherein, When the total acid content of the catalyst is reduced to below 40% during the alkylation reaction, the undeveloped catalyst is obtained. Preferably, the regeneration of the spent catalyst includes: S1. The catalyst to be generated is regenerated by a solvent in the presence of a second solvent; S2. The product obtained in step S1 is subjected to two-stage hydrogen regeneration under hydrogen-exposed conditions. S3. The product obtained in step S2 is subjected to three-stage solvent hydrogen regeneration under hydrogen-exposed conditions and in the presence of a second solvent to obtain a regenerated catalyst.
11. The method according to claim 10, wherein, In step S1, the recovery rate of the medium-strong acid content of the product obtained in step S1 reaches 80-95%. Preferably, in step S1, the second solvent is selected from at least one of ethanol, ethylene glycol and glycerol, and more preferably glycerol and / or ethylene glycol; Preferably, in step S1, the conditions for the first-stage solvent regeneration include: a temperature of 220-400℃, a time of 0.5-24h, and a volume hourly space velocity (VHSV) of 0.01-20h for the second solvent. -1 ; More preferably, in step S1, the conditions for the first-stage solvent regeneration include: a temperature of 250-350°C, a time of 2-12 hours, and a volume hourly space velocity (VHSV) of 0.5-15 h⁻¹ for the second solvent. -1 .
12. The method according to claim 10 or 11, wherein, In step S2, the conditions for the two-stage hydrogen regeneration include: a temperature of 250-400℃, a time of 0.5-24h, a pressure of 0.01-10MPa, and a hydrogen flow rate of 0.001-10000mL / min relative to 1g of fresh catalyst. Preferably, in step S2, the conditions for the two-stage hydrogen regeneration include: a temperature of 260-350℃, a time of 2-20h, a pressure of 0.1-8MPa, and a hydrogen flow rate of 10-800mL / min relative to 1g of fresh catalyst.
13. The method according to claim 10 or 11, wherein, The third solvent is selected from at least one of C6-C12 n-alkanes, alcohols and benzene, preferably C6-C12 n-alkanes; Preferably, the C6-C12 n-alkane is selected from at least one of n-hexane, n-heptane, n-octane, and n-decane; Preferably, the temperature of the three-stage solvent regeneration under hydrogen is 10-100°C higher than the temperature of the two-stage hydrogen regeneration. Preferably, in step S3, the conditions for the three-stage solvent hydrogen regeneration include: a temperature of 260-500℃, a time of 0.5-50 h, a pressure of 0.01-10 MPa, and a volume hourly space velocity (VHSV) of 0.01-15 h⁻¹ for the third solvent. -1 ; More preferably, in step S3, the conditions for the three-stage solvent hydrogen regeneration include: a temperature of 270-450℃, a time of 1-48h, a pressure of 0.01-8MPa, and a volume hourly space velocity (VHSV) of 0.1-10h for the third solvent. -1 .