Copper-nickel-zinc-magnesium catalyst as well as preparation method and application thereof

Abstract

The invention provides a copper-nickel-zinc-magnesium catalyst and a preparation method and application thereof.The preparation method comprises the steps that a carrier is pretreated, a first precursor solution which is subjected to pre-dispersion treatment and contains copper, nickel and zinc, a second precursor solution containing magnesium element and a precipitant solution containing at least two precipitants are prepared, and the copper-nickel-zinc-magnesium catalyst is obtained through a two-step precipitation method. The preparation method comprises the following steps: firstly, adding a first precursor solution and a precipitator solution into a reaction kettle in a parallel flow manner, then adding a second precursor solution and the precipitator solution into the reaction kettle in a parallel flow manner, controlling the reaction temperature and reaction pH in two-step precipitation reaction, then aging and keeping stirring, filtering, washing, drying and roasting to obtain the copper-nickel-zinc-magnesium catalyst, the prepared copper-nickel-zinc-magnesium catalyst is concentrated in particle size, good in dispersity, good in thermal stability, high in fatty alcohol conversion rate and tertiary amine selectivity, small in particle size change before and after amination reaction, still high in fatty alcohol conversion rate and tertiary amine selectivity after being reused for multiple times, and long in service life.

Description

Technical Field

[0001] This application belongs to the field of catalyst preparation technology, specifically relating to a copper-nickel-zinc-magnesium catalyst, its preparation method, and its application. Background Technology

[0002] Aliphatic tertiary amines are an important class of fine chemical intermediates and end products, widely used in surfactants, textile auxiliaries, mineral flotation agents, bactericides, daily chemical products, and oilfield chemicals. Industrially, a new "one-step catalytic amination of fatty alcohols" process is now widely adopted. This process has fewer steps, higher purity, and lower waste. In this new process, the catalytic performance and stability of the catalyst directly affect the yield, selectivity, and production cost of the tertiary amine product. Currently, commonly used catalysts for fatty alcohol amination mainly include copper-chromium catalysts and noble metal-based catalysts.

[0003] US Patent No. 5,075,505 reports a class of copper-chromium-manganese catalysts that achieve high conversion rates of fatty alcohols and selectivity for tertiary amines in the amination reaction of fatty alcohols. This class of multi-metal oxide catalysts, through the synergistic regulation of the hydrogenation activity of copper species and the structural stabilization of chromium and manganese components, effectively suppresses side reactions while ensuring high dispersion of the active metals, thereby improving the selectivity and space-time yield of the target tertiary amine. CN1792442A discloses a copper-chromium catalyst for the catalytic hydrogenation of fatty amides to prepare tertiary amines. This catalyst introduces a third metal component into the traditional Cu-Cr system and supports it on a support, using a co-precipitation method to optimize particle size, specific surface area, and metal dispersion. CN10754888C relates to a catalyst using C... 12 -C 18 The process for preparing mono-aliphatic alkyl dimethyl tertiary amines from fatty nitriles utilizes a noble metal palladium-based catalyst. This patent leverages the excellent hydrogenation and aza-intermediate conversion capabilities of Pd species to achieve high tertiary amine yields and selectivity under suitable reaction conditions, while simultaneously reducing the formation of byproducts.

[0004] While these catalysts can achieve a certain conversion rate of fatty alcohols, they generally suffer from problems such as low thermal stability, uneven dispersion of active metals, and high catalyst costs. Some copper-chromium catalysts contain environmentally sensitive elements such as hexavalent chromium, which imposes higher environmental protection requirements on their preparation, use, and disposal processes, making them less compliant with increasingly stringent safety and environmental regulations. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide a copper-nickel-zinc-magnesium catalyst, its preparation method and application. The copper-nickel-zinc-magnesium catalyst prepared by the method of this application has a concentrated particle size, good dispersibility, good thermal stability, high conversion rate of fatty alcohols and selectivity of tertiary amines, small change in catalyst particle size before and after amination reaction, and still has a high conversion rate of fatty alcohols and selectivity of tertiary amines after multiple reuses, and a long lifespan.

[0006] To address the aforementioned technical problems, this application provides a method for preparing a copper-nickel-zinc-magnesium catalyst, comprising the following steps: Step S1, support pretreatment: The support is treated with acetic acid and then surface modified with a silane coupling agent to obtain a modified support; Preparation of reactant solutions: Prepare a mixed solution containing copper, nickel and zinc elements according to the target loading of copper, nickel and zinc. Add a complexing agent to the mixed solution and perform ultrasonic homogenization to obtain a first precursor solution. Prepare a second precursor solution containing magnesium element. Prepare a precipitant solution containing at least two precipitants. Step S2: Add bottom water and modified carrier to the reactor, stir and heat to the reaction temperature; Step S3: Under stirring, the first precursor solution and the precipitant solution are added to the reactor in parallel stream. When the mass of each active metal ion in the added first precursor solution reaches the target loading of each active metal, the addition of the first precursor solution and the precipitant solution is stopped. The feed ratio of the first precursor solution and the precipitant solution is such that the pH of the reaction solution in the reactor is 6.0-6.5. Step S4: While stirring, the second precursor solution and the precipitant solution are added to the reactor in parallel stream. When the mass of magnesium ions in the added second precursor solution reaches the target magnesium loading, the addition of the second precursor solution and the precipitant solution is stopped. The feed ratio of the second precursor solution and the precipitant solution is such that the pH of the reaction solution in the reactor is 8.5-9.0. Step S5: Aging process while maintaining stirring; Step S6: After filtering and washing the reaction solution from step S5, the solution is dried and calcined to obtain a copper-nickel-zinc-magnesium catalyst.

[0007] Further, the target loading of copper in the copper-nickel-zinc-magnesium catalyst is 8.0%-24.0%, the target loading of nickel is 0.8%-3.9%, the target loading of zinc is 4.0%-8.0%, and the target loading of magnesium is 0.6%-3.0%. The copper precursor in the copper-nickel-zinc-magnesium catalyst is selected from at least one of copper chloride, copper nitrate, and copper sulfate. The nickel precursor in the copper-nickel-zinc-magnesium catalyst is selected from at least one of nickel chloride, nickel nitrate, or nickel acetate. The zinc precursor in the copper-nickel-zinc-magnesium catalyst is selected from at least one of zinc sulfate, zinc nitrate, or zinc acetate. The magnesium precursor in the copper-nickel-zinc-magnesium catalyst is selected from at least one of magnesium sulfate, magnesium nitrate, or magnesium acetate. The mass concentration of the solute in the first precursor solution is 10%-20%.

[0008] Furthermore, the pH of the precipitant solution is 10-14, and the precipitant is selected from at least two of sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide, ammonia, and sodium bicarbonate.

[0009] Furthermore, the carrier is selected from at least one of silicon dioxide, calcium carbonate, and aluminum oxide.

[0010] Further, in step S1, during the carrier pretreatment, the carrier is placed in a 0.1 mol / L-0.5 mol / L acetic acid solution and stirred at room temperature for 30-60 minutes. After filtration, the filter cake is washed with deionized water until neutral and dried at 100-120℃ for 10-14 hours. Then, it is ultrasonically dispersed in a 1%-5% (w / w) silane coupling agent solution for 30-60 minutes, dried at 70-90℃ for 10-14 hours, and calcined at 100-150℃ for 2-4 hours to obtain the modified carrier. The ratio of the total molar amounts of the complexing agent to the total molar amounts of copper, nickel, and zinc in the first precursor solution is 1:(1-2).

[0011] Furthermore, the reaction temperature in step S2 is 30℃-70℃, just like the reaction temperatures in steps S3 and S4.

[0012] Furthermore, in step S5, the aging pH value is 8.0-9.0, the aging temperature is 30℃-70℃, and the aging time is 0h-5h.

[0013] Furthermore, in step S6, the temperature of the washing water is 20℃-60℃, the drying temperature is 80℃-120℃, the drying time is 5h-12h, the calcination temperature is 300℃-700℃, and the calcination time is 1-6 hours.

[0014] This application also provides a copper-nickel-zinc-magnesium catalyst, which is prepared by the above-described preparation method.

[0015] This application also provides the application of the above-mentioned copper-nickel-zinc-magnesium catalyst in the synthesis of aliphatic tertiary amines.

[0016] The beneficial effects of this application are: The preparation method of this application uses a two-step precipitation method. The first step is to first precipitate Cu... 2+ Ni 2+ Zn 2+ The Mg reacts with a precipitant to precipitate, and in the second step... 2+ It reacts with the precipitant to precipitate, avoiding Cu 2+ With Mg 2+ The large pH difference during precipitation leads to uneven distribution of components; by simultaneously containing Cu 2+ Ni 2+ Zn 2+ A complexing agent and ultrasonic homogenization are added to the mixed solution to form stable metal complexes and ensure uniform distribution of metal ions. This results in smaller precipitate particle size and more uniform distribution of components when reacting with the precipitant. The support is treated with acetic acid and surface modified with a silane coupling agent to increase its surface area and enhance its chelating ability for metal ions. Two or more precipitants are used to ensure simultaneous and uniform deposition of the three metal ions from the first precursor solution onto the support. Furthermore, the mechanical strength and anti-sintering ability of the support are improved by controlling the particle size, crystal form, and bonding strength with the support of the final oxide. During the reaction with the precipitant... By controlling the concentration of different metal ions, reaction temperature, pH, and other conditions within the reactor, and under the action of an alkaline solution, the crystal growth rate is controlled, enabling the formation of uniformly sized crystal nuclei, which further grow into catalyst precursors. A stirring aging method is employed to avoid weak interactions between the metal and the support, resulting in a tighter bond between the catalyst particles and the support. The preparation method described in this application involves interconnected and synergistic steps, resulting in catalyst powder with concentrated particle size, good dispersibility, good thermal stability, high conversion rate of fatty alcohols and selectivity for tertiary amines, minimal change in catalyst particle size before and after amination, and high fatty alcohol conversion rate and tertiary amine selectivity even after multiple reuses, demonstrating a long lifespan. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0018] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components.

[0019] Definitions of other specific words and phrases are provided throughout this disclosure. Those skilled in the art will understand that, in many, if not most, cases, such definitions apply to the prior and future use of the words and phrases thus defined.

[0020] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0021] This disclosure provides a method for preparing a copper-nickel-zinc-magnesium catalyst, comprising the following steps: Step S1, support pretreatment: the support is treated with acetic acid and then surface modified with a silane coupling agent to obtain a modified support.

[0022] Preparation of reactant solutions: Prepare a mixed solution containing copper, nickel and zinc elements according to the target loading of copper, nickel and zinc. Add a complexing agent to the mixed solution and perform ultrasonic homogenization to obtain a first precursor solution. Prepare a second precursor solution containing magnesium element. Prepare a precipitant solution containing at least two precipitants.

[0023] Step S2: Add bottom water and the modified carrier to the reactor, stir and heat to the reaction temperature.

[0024] Step S3: Under stirring, the first precursor solution and the precipitant solution are added to the reactor in parallel flow. When the mass of each active metal ion in the added first precursor solution reaches the target loading of each active metal, the addition of the first precursor solution and the precipitant solution is stopped. The addition rates of the first precursor solution, the second precursor solution, and the precipitant solution are such that the pH of the reaction solution in the reactor is 6.0-6.5.

[0025] Step S4: While stirring, the second precursor solution and the precipitant solution are added to the reactor in parallel flow. When the mass of magnesium ions in the added second precursor solution reaches the target magnesium loading, the addition of the second precursor solution and the precipitant solution is stopped. The addition rate of the second precursor solution and the precipitant solution is such that the pH of the reaction solution in the reactor is 8.5-9.0.

[0026] Step S5: Aging process while maintaining stirring.

[0027] Step S6: After filtering and washing the reaction solution from step S5, the solution is dried and calcined to obtain a copper-nickel-zinc-magnesium catalyst.

[0028] The method for preparing the copper-nickel-zinc-magnesium catalyst provided in the above embodiments of this disclosure uses a two-step precipitation method. The first step involves first precipitating Cu... 2+ Ni 2+ Zn 2+ The Mg reacts with a precipitant to precipitate, and in the second step... 2+ It reacts with the precipitant to precipitate, avoiding Cu 2+ With Mg 2+ The large pH difference during precipitation leads to uneven distribution of components; by simultaneously containing Cu 2+ Ni 2+ Zn 2+A complexing agent and ultrasonic homogenization are added to the mixed solution to form stable metal complexes and ensure uniform distribution of metal ions. This results in smaller precipitate particle size and more uniform distribution of components when reacting with the precipitant. The support is treated with acetic acid and surface modified with a silane coupling agent to increase its surface area and enhance its chelating ability for metal ions. Two or more precipitants are used to ensure simultaneous and uniform deposition of the three metal ions from the first precursor solution onto the support. Furthermore, the mechanical strength and anti-sintering ability of the support are improved by controlling the particle size, crystal form, and bonding strength with the support of the final oxide. During the reaction with the precipitant... By controlling the concentration of different metal ions, reaction temperature, pH, and other conditions within the reactor, and under the action of an alkaline solution, the crystal growth rate is controlled, enabling the formation of uniformly sized crystal nuclei, which further grow into catalyst precursors. A stirring aging method is employed to avoid weak interactions between the metal and the support, resulting in a tighter bond between the catalyst particles and the support. The preparation method described in this application involves interconnected and synergistic steps, resulting in catalyst powder with concentrated particle size, good dispersibility, good thermal stability, high conversion rate of fatty alcohols and selectivity for tertiary amines, minimal change in catalyst particle size before and after amination, and high fatty alcohol conversion rate and tertiary amine selectivity even after multiple reuses, demonstrating a long lifespan.

[0029] Specifically, as an example, the pH of the reaction solution in step S3 can be 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, etc. The pH of the reaction solution in step S4 can be 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, etc.

[0030] Specifically, the method for determining when to stop adding the first and second precursor solutions is as follows: the mass of the first precursor solution to be added is calculated theoretically based on the mass of the carrier added in step S2. Specifically, experiments show that the precipitates after the reactions in steps S3 and S4 are basically all precipitated on the carrier, and the Cu in the first precursor solution... 2+ Ni 2+ Zn 2+Each is formulated according to its target loading capacity. Therefore, in step S3, only the required mass of the metal ions needs to be calculated theoretically based on the mass of the carrier and the target loading capacity of one of the metals. Then, the mass of the first precursor solution to be added can be obtained based on the concentration of the metal ions in the first precursor solution and the calculated mass of the metal ions. In step S4, the mass of magnesium ions is calculated theoretically based on the mass of the carrier and the target loading capacity of magnesium. Then, the mass of the second precursor solution to be added can be obtained based on the concentration of magnesium ions in the second precursor solution and the calculated mass of the magnesium ions. The added mass of the first precursor solution, the second precursor solution, and the precipitant solution can be determined by weighing in real time or by judging based on the remaining volume. As an example, the first precursor solution is placed on a weighing balance, and the weight of the remaining first precursor solution is obtained based on the data displayed on the balance, thus obtaining the added mass of the first precursor solution.

[0031] Specifically, during feeding, the first precursor solution, the second precursor solution, and the precipitant solution are added to the reactor using devices capable of controlling the flow rate. For example, metering pumps, peristaltic pumps, or regulating valves with flow meters can be used. By controlling the flow rate of the devices, the addition rates of the first precursor solution, the second precursor solution, and the precipitant solution are controlled, thereby controlling the feed ratios of the first precursor solution and the second precursor solution and the precipitant solution, ensuring that the reaction liquid in the reactor is maintained at the set pH in steps S3 and S4.

[0032] Specifically, in steps S3 and S4, the pH of the reaction solution is measured by an online pH meter. The feed rates of the salt solution and the precipitant solution can be adjusted by the pH to maintain the reaction solution at a stable pH value.

[0033] Specifically, the amount of bottom water added is 1 / 10 to 1 / 2 of the reactor volume. For example, the amount of bottom water added can be 1 / 10, 1 / 9, 1 / 8, 1 / 4, 2 / 7, 1 / 3, 1 / 2, etc., of the reactor volume. Preferably, the amount of bottom water added is 1 / 8 to 1 / 4 of the reactor volume.

[0034] Specifically, in steps S2-S4, the stirring speed is between 300 rpm and 700 rpm. As an example, the stirring speed in steps S2-S4 can be 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, etc. Preferably, the stirring speed is 400 rpm.

[0035] Specifically, heating to the reaction temperature in step S2 refers to heating to the temperature that needs to be controlled when the first precursor solution and precipitant solution react in step S3.

[0036] In some embodiments, the target loading of copper in the copper-nickel-zinc-magnesium catalyst is 8.0%-24.0%, the target loading of nickel is 0.8%-3.9%, the target loading of zinc is 4.0%-8.0%, and the target loading of magnesium is 0.6%-3.0%.

[0037] The copper precursor in the copper-nickel-zinc-magnesium catalyst is selected from at least one of copper chloride, copper nitrate, and copper sulfate. Preferably, the copper precursor is copper nitrate.

[0038] In the copper-nickel-zinc-magnesium catalyst, the nickel precursor is selected from at least one of nickel chloride, nickel nitrate, or nickel acetate. Preferably, the nickel precursor is nickel nitrate.

[0039] In the copper-nickel-zinc-magnesium catalyst, the zinc precursor is selected from at least one of zinc sulfate, zinc nitrate, or zinc acetate. Preferably, the zinc precursor is zinc nitrate.

[0040] In the copper-nickel-zinc-magnesium catalyst, the magnesium precursor is selected from at least one of magnesium sulfate, magnesium nitrate, or magnesium acetate. Preferably, the magnesium precursor is magnesium nitrate.

[0041] The mass concentration of the solute in the first precursor solution is 10%-20%. The solute in the first precursor solution is a copper salt, a nickel salt, or a zinc salt. As an example, the solute in the first precursor solution is copper nitrate, nickel nitrate, and zinc nitrate, and the total mass fraction of copper nitrate, nickel nitrate, and zinc nitrate in the first precursor solution can be 10%, 12%, 15%, 17%, 20%, etc.

[0042] In some embodiments, the pH of the precipitant solution is 10-14, and the precipitant is selected from at least two of sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide, ammonia, and sodium bicarbonate. As an example, the pH of the precipitant solution can be 10, 11, 12, 13, 14, etc. The precipitant can be sodium carbonate and sodium bicarbonate, ammonia and sodium carbonate, potassium carbonate, potassium hydroxide, and ammonia, etc.

[0043] In some embodiments, the support is selected from at least one of silica, calcium carbonate, and alumina. As an example, the support can be a single support such as calcium carbonate, alumina, or silica, or a composite support such as silica-alumina or calcium carbonate-silica-alumina.

[0044] In some embodiments, during the carrier pretreatment in step S1, the carrier is placed in a 0.1 mol / L-0.5 mol / L acetic acid solution, stirred at room temperature for 30-60 minutes, filtered, and the filter cake is washed with deionized water until neutral. It is then dried at 100-120°C for 10-14 hours, and then ultrasonically dispersed in a 1%-5% (w / w) silane coupling agent solution for 30-60 minutes. It is dried at 70-90°C for 10-14 hours and calcined at 100-150°C for 2-4 hours to obtain the modified carrier. As an example, the molar concentration of the acetic acid solution can be 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, etc. The stirring speed during acetic acid treatment can be 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, etc. The drying temperature after acetic acid treatment can be 100℃, 105℃, 110℃, 115℃, 120℃, etc., and the drying time can be 10h, 11h, 12h, 13h, 14h, etc. The mass fraction of the silane coupling agent can be 1%, 2%, 3%, 4%, 5%, etc. The ultrasonic dispersion time can be 30min, 35min, 40min, 45min, 50min, 55min, 60min, etc. The drying temperature after ultrasonic dispersion can be 70℃, 75℃, 80℃, 85℃, 90℃, etc., and the drying time can be 10h, 11h, 12h, 13h, 14h, etc. The calcination temperature can be 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, etc., and the calcination time can be 2h, 2.5h, 3h, 3.5h, 4h, etc.

[0045] Specifically, the silane coupling agent can be KH-550 (γ-aminopropyltriethoxysilane), KH-560 (γ-(2,3-epoxypropoxy)propyltrimethoxysilane), KH-570 (γ-(methacryloyloxy)propyltrimethoxysilane), etc.

[0046] The ratio of the total molar amounts of the complexing agent to the total molar amounts of copper, nickel, and zinc in the first precursor solution is 1:(1-2). As an example, the ratio of the total molar amounts of the complexing agent to the total molar amounts of copper, nickel, and zinc in the first precursor solution can be 1:1, 1:1.2, 1:1.5, 1:1.7, 1:2, etc.

[0047] In some embodiments, the reaction temperature in step S2 is 30°C-70°C, as are the reaction temperatures in steps S3 and S4. For example, the reaction temperature in step S2 can be 30°C, 40°C, 50°C, 60°C, 70°C, etc. Specifically, the reaction temperatures in steps S3 and S4 can be the same or different. For example, the reaction temperature in step S3 can be 40°C, and the reaction temperature in step S4 can be 50°C. Or, the reaction temperatures in steps S3 and S4 can both be 50°C.

[0048] In some embodiments, in step S5, the aging pH value is 8.0-9.0, the aging temperature is 30℃-70℃, and the aging time is 0h-5h. For example, the aging pH value can be 8.0, 8.2, 8.4, 8.6, 8.8, 9.0, etc. The aging temperature can be 30℃, 40℃, 50℃, 60℃, 70℃, etc. The aging time can be 0h, 1h, 2h, 3h, 4h, 5h.

[0049] In some embodiments, in step S6, the temperature of the washing water during washing is 20℃-60℃, the drying temperature is 80℃-120℃, the drying time is 5h-12h, the calcination temperature is 300℃-700℃, and the calcination time is 1-6 hours. As an example, the temperature of the washing water during washing can be 20℃, 30℃, 40℃, 50℃, 60℃, etc. The drying temperature can be 80℃, 90℃, 100℃, 110℃, 120℃, etc. The drying time can be 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, etc. The calcination temperature can be 300℃, 400℃, 500℃, 600℃, 700℃, etc. Preferably, the calcination temperature is 400℃-500℃. The calcination time can be 1h, 2h, 3h, 4h, 5h, 6h, etc. Preferably, the calcination time is 3h-6h.

[0050] This disclosure also provides a copper-nickel-zinc-magnesium catalyst, which is prepared using the above-described method for preparing copper-nickel-zinc-magnesium catalysts.

[0051] This disclosure also provides an application of a copper-nickel-zinc-magnesium catalyst in the synthesis of aliphatic tertiary amines.

[0052] The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Where techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0053] Example 1 Step S1, carrier pretreatment: Calcium carbonate was added to a 0.3 mol / L acetic acid solution and stirred at room temperature for 40 min. The solid particles were washed with deionized water until neutral and then dried at 110 °C for 12 h. The dried solid particles were then placed in a 1% (w / w) γ-aminopropyltriethoxysilane (KH550) ethanol solution and ultrasonically dispersed for 30 min. After drying at 80 °C for 12 h, the particles were calcined at 120 °C for 2 h to obtain modified calcium carbonate.

[0054] Preparation of reactant solutions: A mixed solution containing 8.5% copper nitrate, 1.5% nickel nitrate, and 4.2% zinc nitrate by mass was prepared using copper nitrate trihydrate, nickel nitrate hexahydrate, and zinc nitrate hexahydrate as solutes and deionized water as solvent. Citric acid was added to the mixed solution and the mixture was ultrasonically homogenized to obtain the first precursor solution. The molar ratio of citric acid to the total metal ions in the first precursor solution was 1:1. Magnesium nitrate hexahydrate was added to deionized water to prepare a 3% magnesium nitrate solution by mass. Sodium carbonate and sodium bicarbonate were added to deionized water at a mass ratio of 1:1 to prepare a precipitant solution with a pH of 12.

[0055] Step S2: Add 1 / 5 of the volume of bottom water and 30 grams of the modified calcium carbonate prepared in step 1 to the reactor equipped with an online pH meter, stir at 300 rpm, and heat to 30°C.

[0056] Step S3: Place the first precursor solution and the precipitant solution on a balance respectively. While stirring, add the first precursor solution and the precipitant solution to the reaction vessel in parallel. Control the addition rate of the first precursor solution and the precipitant solution to make the pH of the reaction solution 6.0. When 175g of the first precursor solution has been added (the initial reading of the balance minus the real-time reading is the mass of the first precursor solution added), stop adding the first precursor solution and the precipitant solution.

[0057] Step S4: Place the magnesium nitrate solution on a balance. While stirring, add the magnesium nitrate solution and the precipitant solution to the reaction vessel in parallel. Control the addition rate of the magnesium nitrate solution and the precipitant solution to make the pH of the reaction solution 8.5. When 170g of magnesium nitrate solution has been added (the initial reading on the balance minus the real-time reading is the mass of the added second precursor solution), stop adding the magnesium nitrate solution and the precipitant solution.

[0058] Step S5: Keep stirring and carry out aging treatment at a temperature of 30°C, a pH of 8.0, and an aging time of 3 hours.

[0059] Step S6: After filtering the reaction solution from step S5, a precipitate is obtained. The precipitate is washed with deionized water at 40°C until the conductivity of the washing solution is less than 500 microsiemens per centimeter. Washing is stopped, and filtration begins. The filter cake is dried at 110°C for 10 hours and then placed in a muffle furnace and calcined at 400°C for 3 hours to obtain a copper-nickel-zinc-magnesium catalyst.

[0060] Testing revealed that the copper-nickel-zinc-magnesium catalyst contained 12.0% copper, 2.6% nickel, 7.5% zinc, and 2% magnesium.

[0061] Example 2 Step S1, carrier pretreatment: Calcium carbonate was added to a 0.1 mol / L acetic acid solution and stirred at room temperature for 30 min. The solid particles were washed with deionized water until neutral and then dried at 120 °C for 10 h. The dried solid particles were then placed in a 3% (w / w) γ-aminopropyltriethoxysilane (KH550) ethanol solution and ultrasonically dispersed for 40 min. After drying at 70 °C for 14 h, the particles were calcined at 100 °C for 4 h to obtain modified silica.

[0062] Preparation of reactant solutions: A mixed solution containing 16.4% copper nitrate, 0.6% nickel nitrate, and 2.7% zinc nitrate by mass was prepared using copper nitrate trihydrate, nickel nitrate hexahydrate, and zinc nitrate hexahydrate as solutes and deionized water as solvent. Citric acid was added to the mixed solution and the mixture was ultrasonically homogenized to obtain the first precursor solution. The molar ratio of citric acid to the total metal ions in the first precursor solution was 1:1.5. Magnesium nitrate hexahydrate was added to deionized water to prepare a 1.3% magnesium nitrate solution by mass. Sodium carbonate, sodium bicarbonate, and ammonia were added to deionized water in a mass ratio of 1:1:1 to prepare a precipitant solution with a pH of 10.

[0063] Step S2: Add half the volume of bottom water and 30 grams of the modified silica prepared in step 1 to the reactor equipped with an online pH meter, stir at 400 rpm, and heat to 50°C.

[0064] Step S3: Place the first precursor solution and the precipitant solution on a balance respectively. While stirring, add the first precursor solution and the precipitant solution to the reaction vessel in parallel. Control the addition rate of the first precursor solution and the precipitant solution to make the pH of the reaction solution 6.3. When 205g of the first precursor solution has been added (the initial reading of the balance minus the real-time reading is the mass of the first precursor solution added), stop adding the first precursor solution and the precipitant solution.

[0065] Step S4: Place the magnesium nitrate solution on a balance. While stirring, add the magnesium nitrate solution and the precipitant solution to the reaction vessel in parallel. Control the addition rate of the magnesium nitrate solution and the precipitant solution to make the pH of the reaction solution 8.8. When 145g of magnesium nitrate solution has been added (the initial reading on the balance minus the real-time reading is the mass of the added second precursor solution), stop adding the magnesium nitrate solution and the precipitant solution.

[0066] Step S5: Keep stirring and carry out aging treatment at a temperature of 50°C, a pH of 8.8, and an aging time of 5 hours.

[0067] Step S6: After filtering the reaction solution from step S5, a precipitate is obtained. The precipitate is washed with deionized water at 20°C until the conductivity of the washing solution is less than 500 microsiemens per centimeter. Washing is stopped, and filtration begins. The filter cake is dried at 80°C for 12 hours and then placed in a muffle furnace and calcined at 300°C for 6 hours to obtain a copper-nickel-zinc-magnesium catalyst.

[0068] Testing revealed that the copper-nickel-zinc-magnesium catalyst contained 23.9% copper, 1.05% nickel, 5% zinc, and 0.65% magnesium.

[0069] Example 3 Step S1, carrier pretreatment: Alumina was added to a 0.5 mol / L acetic acid solution and stirred at room temperature for 60 min. The solid particles were washed with deionized water until neutral and then dried at 100 °C for 14 h. The dried solid particles were then placed in a 5% (w / w) γ-aminopropyltriethoxysilane (KH550) ethanol solution and ultrasonically dispersed for 60 min. After drying at 90 °C for 10 h, the particles were calcined at 150 °C for 3 h to obtain modified alumina.

[0070] Preparation of reactant solutions: A mixed solution containing 3.9% copper chloride, 1.9% nickel chloride, and 4.5% zinc sulfate (by mass) was prepared using copper chloride dihydrate, nickel chloride hexahydrate, and zinc sulfate heptahydrate as solutes and deionized water as solvent. Citric acid was added to the mixed solution and the mixture was ultrasonically homogenized to obtain the first precursor solution. The molar ratio of citric acid to the total metal ions in the first precursor solution was 1:2. Magnesium acetate tetrahydrate was added to deionized water to prepare a 6.2% magnesium acetate solution. Sodium carbonate and sodium hydroxide were added to deionized water at a mass ratio of 1:2 to prepare a precipitant solution with a pH of 14.

[0071] Step S2: Add 1 / 8 of the reactor volume of bottom water and 30 grams of the modified alumina prepared in step 1 to the reactor equipped with an online pH meter, stir at 700 rpm, and heat to 70°C.

[0072] Step S3: Place the first precursor solution and the precipitant solution on a balance respectively. While stirring, add the first precursor solution and the precipitant solution to the reaction vessel in parallel. Control the addition rate of the first precursor solution and the precipitant solution to make the pH of the reaction solution 6.5. When 190g of the first precursor solution has been added (the initial reading of the balance minus the real-time reading is the mass of the first precursor solution added), stop adding the first precursor solution and the precipitant solution.

[0073] Step S4: Place the magnesium acetate solution on a balance and, while stirring, add the magnesium acetate solution and the precipitant solution in parallel into the reaction vessel. Control the addition rate of the magnesium acetate solution and the precipitant solution to make the pH of the reaction solution 9. When 120g of magnesium acetate solution has been added (the initial reading on the balance minus the real-time reading is the mass of the added second precursor solution), stop adding the magnesium acetate solution and the precipitant solution.

[0074] Step S5: Keep stirring and carry out aging treatment at a temperature of 70°C, a pH of 9.0, and an aging time of 0.5 hours.

[0075] Step S6: After filtering the reaction solution from step S5, a precipitate is obtained. The precipitate is washed with deionized water at 60°C until the conductivity of the washing solution is less than 500 microsiemens per centimeter. Washing is stopped, and filtration begins. The filter cake is dried at 120°C for 5 hours and then placed in a muffle furnace and calcined at 700°C for 1 hour to obtain a copper-nickel-zinc-magnesium catalyst.

[0076] Testing revealed that the copper-nickel-zinc-magnesium catalyst contained 8.2% copper, 3.8% nickel, 8.1% zinc, and 3.0% magnesium.

[0077] Comparative Example Step S1: A first precursor solution containing 8.5% copper nitrate, 1.5% nickel nitrate, 4.2% zinc nitrate, and 3% magnesium nitrate by mass is prepared using copper nitrate trihydrate, nickel nitrate hexahydrate, zinc nitrate hexahydrate, and magnesium nitrate hexahydrate as solutes and deionized water as solvent. Sodium carbonate is added to deionized water to prepare a precipitant solution with a pH of 10.

[0078] Step S2: Add 1 / 5 of the reactor volume of bottom water and 30 grams of calcium carbonate to the reactor equipped with an online pH meter, stir at 300 rpm, and heat to 30°C.

[0079] Step S3: Place the precursor solution and precipitant solution on a balance, and add them to the reaction vessel in parallel while stirring. Control the addition rate of the precursor solution and precipitant solution to make the pH of the reaction solution 6.0. When 175g of the precursor solution has been added (the mass of the added precursor solution is the initial reading of the balance minus the real-time reading), stop adding the precursor solution and precipitant solution.

[0080] Step S4: Stop stirring and perform aging treatment at 30°C, pH 8.0, and for 8 hours. Step S5: After filtering the reaction solution from step S4, a precipitate is obtained. The precipitate is washed with deionized water at 40°C until the conductivity of the washing solution is less than 500 microsiemens per centimeter. Washing is stopped, and filtration begins. The filter cake is dried at 110°C for 10 hours and then placed in a muffle furnace and calcined at 400°C for 3 hours to obtain a copper-nickel-zinc-magnesium catalyst.

[0081] The performance of the copper-nickel-zinc-magnesium catalysts prepared in Examples 1 to 3 and the comparative examples was tested.

[0082] The specific surface area of ​​the catalysts prepared in Examples 1 to 3 and the comparative examples was measured using the gas adsorption method. The measurement results are shown in Table 1.

[0083] The copper-nickel-zinc-magnesium catalysts prepared in Examples 1-3 and the comparative examples were subjected to amination experiments of fatty alcohols. The experimental procedure was as follows: 150 g of dodecanol and 2.5 g of catalyst were added to a reactor equipped with a stirrer, temperature probe, gas inlet pipe, and water separator. After starting the stirring function, hydrogen gas was introduced to perform system displacement operation, and then the temperature was raised to 175°C and reacted at 175°C for 40 minutes. Then, dimethylamine was introduced, and the reaction temperature was raised to 220°C. The volume fraction of dimethylamine in the mixed gas was stabilized at 40% by adjusting the flow rates of hydrogen and dimethylamine. The water generated during the reaction was separated and collected by the water separator, and the refluxed organic phase was returned to the reactor to continue participating in the reaction; the tail gas was treated by acid absorption and then vented. Samples were taken every 1 hour during the reaction, and the reaction was stopped after 4 hours. The catalyst was separated from the reaction liquid, and the composition and content of the sample after the reaction were analyzed by gas chromatography. The conversion rate of dodecanol and the selectivity of tertiary amines were calculated. The calculation results are shown in Table 1.

[0084] Catalyst reuse: After the previous reaction, when separating the catalyst from the reaction solution, the reaction solution was removed from the reactor, while the catalyst remained in the reactor. 150g of dodecanol was added again, and the reaction was carried out for 4 hours following the experimental steps described above. This process was repeated for a total of 5 reactions.

[0085] Before and after five consecutive fatty alcohol amination reactions, the compact density and particle size of the copper-nickel-zinc-magnesium catalysts prepared in Examples 1 to 3 and the comparative examples were measured using a laser particle size analyzer. The dodecanol conversion rate, tertiary amine selectivity, and catalyst particle size distribution before and after the five reactions are shown in Table 2.

[0086] Table 1.

[0087] Table 2.

[0088] As shown in Tables 1 and 2, the catalysts prepared in Examples 1-3 exhibited 100% conversion of dodecanol and over 97% selectivity for tertiary amines in the fatty alcohol amination reaction experiments, significantly higher than the comparative example. Furthermore, after five consecutive fatty alcohol amination reaction experiments, the catalyst particle size did not increase significantly, and the selectivity for tertiary amines did not decrease significantly. In contrast, the catalyst prepared in the comparative example showed a significant increase in particle size and a significant decrease in tertiary amine selectivity after five consecutive fatty alcohol amination reaction experiments. The steps in preparing the copper-nickel-zinc-magnesium catalyst in this disclosure are interconnected and synergistic, resulting in a catalyst with high fatty alcohol conversion and tertiary amine selectivity, good thermal stability, minimal particle size change before and after amination, and high fatty alcohol conversion and tertiary amine selectivity even after multiple reuses, demonstrating a long lifespan.

[0089] The text in this disclosure is provided by way of example only to aid in understanding this disclosure. It should not be construed as limiting the scope of this disclosure in any way. Although certain embodiments and examples have been provided, it will be apparent to those skilled in the art, based on the content disclosed herein, that changes can be made to the illustrated embodiments and examples without departing from the scope of this disclosure.

[0090] Although this disclosure has been described with reference to exemplary embodiments, various changes and modifications may be suggested to those skilled in the art. This disclosure is intended to cover such changes and modifications that fall within the scope of the appended claims.

[0091] Nothing described in this disclosure should be construed as implying that any particular element, step, or function is an essential element that must be included within the scope of the claims. The scope of the patent subject matter is defined only by the claims.

Claims

1. A method for preparing a copper-nickel-zinc-magnesium catalyst, characterized in that, Includes the following steps: Step S1, support pretreatment: The support is treated with acetic acid and then surface modified with a silane coupling agent to obtain a modified support; Preparation of reactant solutions: Prepare a mixed solution containing copper, nickel and zinc elements according to the target loading of copper, nickel and zinc. Add a complexing agent to the mixed solution and perform ultrasonic homogenization to obtain a first precursor solution. Prepare a second precursor solution containing magnesium element. Prepare a precipitant solution containing at least two precipitants. Step S2: Add bottom water and the modified carrier to the reactor, stir and heat to the reaction temperature; Step S3: Under stirring, the first precursor solution and the precipitant solution are added to the reactor in parallel. When the mass of each active metal ion in the added first precursor solution reaches the target loading of each active metal, the addition of the first precursor solution and the precipitant solution is stopped. The feed ratio of the first precursor solution and the precipitant solution is such that the pH of the reaction solution in the reactor is 6.0-6.

5. Step S4: Under stirring, the second precursor solution and the precipitant solution are added to the reactor in parallel. When the mass of magnesium ions in the added second precursor solution reaches the target magnesium loading, the addition of the second precursor solution and the precipitant solution is stopped. The feed ratio of the second precursor solution and the precipitant solution is such that the pH of the reaction solution in the reactor is 8.5-9.

0. Step S5: Aging process while maintaining stirring; Step S6: After filtering and washing the reaction solution from step S5, the solution is dried and calcined to obtain a copper-nickel-zinc-magnesium catalyst.

2. The method for preparing the copper-nickel-zinc-magnesium catalyst according to claim 1, characterized in that, The target loading of copper in the copper-nickel-zinc-magnesium catalyst is 8.0%-24.0%, the target loading of nickel is 0.8%-3.9%, the target loading of zinc is 4.0%-8.0%, and the target loading of magnesium is 0.6%-3.0%. The copper precursor in the copper-nickel-zinc-magnesium catalyst is selected from at least one of copper chloride, copper nitrate, and copper sulfate. The nickel precursor in the copper-nickel-zinc-magnesium catalyst is selected from at least one of nickel chloride, nickel nitrate, or nickel acetate. The zinc precursor in the copper-nickel-zinc-magnesium catalyst is selected from at least one of zinc sulfate, zinc nitrate, or zinc acetate. The magnesium precursor in the copper-nickel-zinc-magnesium catalyst is selected from at least one of magnesium sulfate, magnesium nitrate, or magnesium acetate. The mass concentration of the solute in the first precursor solution is 10%-20%.

3. The method for preparing the copper-nickel-zinc-magnesium catalyst according to claim 1, characterized in that, The pH of the precipitant solution is 10-14, and the precipitant is selected from at least two of sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide, ammonia, and sodium bicarbonate.

4. The method for preparing the copper-nickel-zinc-magnesium catalyst according to claim 1, characterized in that, The carrier is selected from at least one of silicon dioxide, calcium carbonate, and aluminum oxide.

5. The method for preparing the copper-nickel-zinc-magnesium catalyst according to claim 1, characterized in that, In step S1, during the carrier pretreatment, the carrier is placed in a 0.1 mol / L-0.5 mol / L acetic acid solution and stirred at room temperature for 30-60 minutes. After filtration, the filter cake is washed with deionized water until neutral and dried at 100-120℃ for 10-14 hours. Then, it is ultrasonically dispersed in a 1%-5% (w / w) silane coupling agent solution for 30-60 minutes, dried at 70-90℃ for 10-14 hours, and calcined at 100-150℃ for 2-4 hours to obtain the modified carrier. The ratio of the total molar amount of the complexing agent to the total molar amount of copper, nickel and zinc in the first precursor solution is 1:(1-2).

6. The method for preparing the copper-nickel-zinc-magnesium catalyst according to claim 1, characterized in that, The reaction temperature in step S2 is the same as the reaction temperature in steps S3 and S4, which is 30℃-70℃.

7. The method for preparing the copper-nickel-zinc-magnesium catalyst according to claim 1, characterized in that, In step S5, the aging pH value is 8.0-9.0, the aging temperature is 30℃-70℃, and the aging time is 0h-5h.

8. The method for preparing the copper-nickel-zinc-magnesium catalyst according to claim 1, characterized in that, In step S6, the washing water temperature is 20℃-60℃, the drying temperature is 80℃-120℃, the drying time is 5h-12h, the calcination temperature is 300℃-700℃, and the calcination time is 1-6 hours.

9. A copper-nickel-zinc-magnesium catalyst, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of the copper-nickel-zinc-magnesium catalyst according to claim 9 in the synthesis of aliphatic tertiary amines.

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