Process for extracting ketonization reaction catalyst from high-iron solid waste and preparing acetone

Abstract

The invention relates to a process for extracting a ketonization catalyst from high-iron solid waste and preparing acetone, which comprises the following steps: firstly, carrying out water washing pretreatment, acid pickling and filtration on high-iron fly ash, collecting filtrate, adding MnCl into the filtrate, dropwise adding an alkaline solvent to adjust the pH value to form precipitate, and carrying out solid-liquid separation and reduction treatment to finally obtain the ketonization catalyst; acetic acid is gasified by high-pressure steam and then enters a tubular constant-temperature packed bed reactor, a catalyst is uniformly filled, pressurized steam or molten salt is adopted for circulating heat supply outside, and stable reaction is ensured; shell pass fluid distribution is optimized through axial tube nest flow, and the catalyst is prevented from being inactivated due to local overheating; high-pressure steam is recycled to the vaporizer after heat exchange, so that heat energy recovery is realized, and the energy efficiency is improved; and finally, separating the product to recover acetone, and recycling unreacted acetic acid. The catalyst disclosed by the invention is low in preparation cost, simple and convenient in method, high in activity, long in service life and reproducible, and the acetone production process is low-carbon, environment-friendly, economical, efficient and sustainable.

Description

Technical Field

[0001] The present invention relates to the fields of materials science and engineering technology, and particularly relates to a process for extracting a ketonization reaction catalyst from high-speed rail solid waste and preparing acetone. Background Art

[0002] Acetone is an important chemical product, widely used in multiple industries such as medicine, paint, resin, and pesticides. The demand for acetone in these fields is continuously increasing. Currently, acetone is mainly produced industrially through the cumene process and obtained as a by-product of phenol production. The reaction equation is as follows:

[0003]

[0004] However, this process has many problems: The catalysts used in it are mainly aluminum chloride or phosphoric acid, which easily cause serious corrosion of equipment; traditional shell-and-tube reactors are generally used in production, and partial oxidation / combustion methods are difficult to precisely control. The temperature in the reactor is prone to runaway temperature, seriously affecting production efficiency, resulting in fluctuations in product quality, reducing the purity of acetone, and even possibly causing safety accidents. Currently, the purity of the finished acetone is only 48%, and there is no international solution to effectively address the runaway temperature problem. In addition, this process relies on crude oil derivative benzene as a raw material, and the production cost of acetone fluctuates with the crude oil price, increasing cost uncertainty. At the same time, up to 2.55 tons of carbon dioxide are emitted per ton of acetone produced, seriously affecting the sustainability of this process.

[0005] In contrast, the technical route of directly catalytically synthesizing acetone from acetic acid in the gas phase is milder and simpler, and only requires relatively simple acetic acid raw materials to achieve high-efficiency production. The reaction equation is as follows:

[0006]

[0007] Currently, patents regarding the preparation of acetone from acetic acid include: Patent CN100363098C introduces an alumina catalyst loaded with rare earth oxides. However, this catalyst requires loading a large amount of different types of rare earth oxides, resulting in a complex preparation process and high cost; Patent CN104174397A describes a catalyst with activated carbon and oxides as carriers, loaded with one or several components of Fe2O3, Co3O4, SiO2, and Al2O3. However, its preparation process is also complex, and the catalytic reaction requires additional pressure conditions.

[0008] In view of the above problems, the present invention proposes to use high-speed rail solid waste as a raw material, extract useful elements from it, and prepare a high-quality acetic acid ketonization catalyst. And a process for preparing acetone is proposed, using bio-based acetic acid as a raw material to directly prepare acetone through a one-step reaction, greatly simplifying the reaction process, reducing equipment investment costs and production costs. Summary of the Invention

[0009] The object of the present invention is to overcome the problems existing in the prior art and provide a process for extracting a ketonization reaction catalyst from high-speed rail solid waste and preparing acetone. This process not only improves the production efficiency of acetone but also has the advantages of low carbon, environmental protection, low cost, high efficiency, and sustainable development, providing a brand-new green solution for acetone production.

[0010] To achieve the above technical object and reach the above technical effect, the present invention is realized through the following technical solutions:

[0011] A method for extracting a ketonization reaction catalyst from high-speed rail solid waste, the process comprising the following steps:

[0012] Step S1.1: Pretreatment: Immerse the high-speed rail solid waste fly ash in deionized water to remove soluble substances therein, and then perform deionized water washing and drying pretreatment;

[0013] Step S1.2: Acid pickling: Perform hydrochloric acid pickling reaction on the pretreated high-speed rail solid waste fly ash, filter and collect the filtrate;

[0014] Step S1.3: Precipitation: Add a certain amount of MnCl2 to the obtained filtrate, and then dropwise add an alkaline solvent to the filtrate under stirring conditions until the pH value reaches 6 - 10 and stop;

[0015] Step S1.4: Separation: Perform solid-liquid separation on the precipitation mixture, and the obtained solid is the catalyst precursor after drying;

[0016] Step S1.5: Reduction: Grind the catalyst precursor and perform reduction treatment to obtain the ketonization reaction catalyst.

[0017] Further, in the step S1.1, the volume ratio of the high-speed rail solid waste fly ash to deionized water is 1:10, and the soaking time is 24 hours.

[0018] Further, in the step S1.1, the pretreatment conditions are 110°C and 24 hours.

[0019] Further, in the step S1.2, the mass ratio of the high-speed rail solid waste fly ash to hydrochloric acid is 1:2, and the reaction conditions are 70°C and 2 hours.

[0020] Further, in the step S1.3, the alkaline solvent is NaOH or Na2CO3, and its concentration is 1 - 2 mol / L.

[0021] Further, in the step S1.4, the specific method of solid-liquid separation is as follows: After centrifuging at 8000 - 10000 r / min for 10 minutes, the supernatant is poured off, deionized water is added to the precipitate and ultrasonic treatment is carried out for 10 minutes, and then centrifugal separation is carried out again, and this process is repeated four times.

[0022] Further, in the step S1.5, the reduction conditions are: 5 - 10 vol% H2 or CO in the gas for 2 - 5 hours.

[0023] A reaction process for preparing acetone by extracting a ketonization reaction catalyst from high-iron solid waste, the process comprising the following steps:

[0024] Step S2.1: Raw material vaporization: First, acetic acid is introduced into the raw material vaporizer and vaporized by high-pressure steam to ensure that the raw material entering the reactor is in a gaseous state, thereby improving the reaction efficiency and uniformity;

[0025] Step S2.2: Tube-type constant-temperature packed bed reactor: The vaporized acetic acid is introduced into the tube-type constant-temperature packed bed reactor. Among them, the ketonization reaction catalyst is formed into tablets and uniformly filled in the tube-type constant-temperature packed bed reactor. The outside of the tube-type constant-temperature packed bed reactor uses pressurized steam or molten salt to circulate to provide the required heat to meet the endothermic demand of the acetic acid ketonization reaction. Through the shell-side medium flow mode of axial tube flow, the shell-side fluid flows parallel in the tube direction, avoiding the problem of uneven flow caused by the traditional baffle structure, effectively ensuring the temperature stability of the catalyst bed layer. At the same time, the axial flow mode can improve the uniformity of the radial temperature distribution inside the catalyst bed layer, effectively reducing the risk of sintering inactivation of the ketonization reaction catalyst due to local overheating;

[0026] Step S2.3: The high-pressure steam used to heat the tube-type constant-temperature packed bed reactor enters the acetic acid raw material vaporizer after heat exchange to vaporize acetic acid, realizing the secondary utilization of heat energy. This design can efficiently recover the heat of the high-pressure steam and make the process more energy-saving;

[0027] Step S2.4: Product separation and circulation: The product coming out of the tube-type constant-temperature packed bed reactor enters the condenser, and the product is condensed by cooling water. After passing through the gas-liquid separation tank, acetone and CO2 are separated. The unreacted acetic acid and product water separated are re-entered into the tube-type constant-temperature packed bed reactor to form a circulation system, realizing the maximum utilization rate of the raw materials and reducing the raw material consumption and production cost.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention uses high-iron solid waste as a raw material and converts it into a high-value-added material, which can effectively reduce waste emissions and promote the reuse and recycling of resources.

[0030] 2. The present invention can achieve the full utilization of solid waste, realize the recycling of acid and alkali substances and zero emission; the solid residue rich in aluminum and silicon generated by pickling can be used as a cement additive; the solution containing only magnesium chloride after filtration and precipitation can be used to prepare magnesium oxide and realize the recovery of hydrogen chloride.

[0031] 3. The preparation of the catalyst of the present invention is carried out under mild conditions, with a simple method, without the need for a protective gas, low cost, and significant economic benefits.

[0032] 4. The catalyst prepared by the present invention exhibits excellent catalytic activity and stability, significantly reduces the cost of the subsequent product separation process, further improves the economic benefits and operation convenience of the overall process, and effectively solves the problem of equipment corrosion caused by the catalyst in the cumene process.

[0033] 5. Compared with the existing cumene process, the present invention prepares acetone by the one-step method of acetic acid ketonization, improves the production efficiency, and effectively gets rid of the dependence on petroleum raw materials.

[0034] 6. The present invention uses a shell-and-tube constant-temperature packed bed reactor, improves the structure of the traditional reactor where no tubes are arranged in the baffle area, changes the flow mode of the shell-side medium from baffle flow to axial tube flow, effectively solves the problem of unstable temperature of the catalyst bed layer, and reduces the risk of accidents caused by temperature runaway and quality fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic diagram of the ketonization reaction process flow of the present invention;

[0036] Figure 2 is the ketonization test result of the fly ash catalyst in Test Example 1 of the present invention;

[0037] Figure 3 is the comparison result of the ketonization reaction of the fly ash catalyst in Test Example 1 of the present invention and the catalyst synthesized from pure reagents at a temperature of 400°C. DETAILED DESCRIPTION OF THE INVENTION

[0038] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0039] Example 1

[0040] This example provides a method for extracting a ketonization reaction catalyst from high-iron solid waste, which is prepared according to the following steps:

[0041] Step S1.1: Pretreatment of fly ash: Soak 5 g of fly ash in deionized water for 24 hours, then wash it with water, and then dry it at 110°C for 24 hours;

[0042] Step S1.2: Pickling: Add 10 g of hydrochloric acid with a mass concentration of 32% to the pretreated fly ash, stir and react at 70 °C for two hours, the rotation speed of the magnetic stirrer is 200 r / min, then perform micro-porous membrane filtration and collect the filtrate;

[0043] Step S1.3: Precipitation: Add 0.7 g of MnCl2 to the filtrate and stir until completely dissolved. Then, at room temperature, slowly dropwise add 2 mol / L NaOH solution to the solution (2 mL / min) until the pH value of the solution reaches 10. During the dropping process, the stirring speed is 300 r / min;

[0044] Step S1.4: Separation: Centrifuge the obtained precipitation solution for 10 min at a rotation speed of 8000 r / min, then pour out the supernatant and collect the precipitate. Then, add 200 mL of deionized water to the precipitate and perform ultrasonic treatment for 10 minutes, and then perform centrifugation again. Repeat this step four times;

[0045] Drying: Dry the obtained precipitate in an air atmosphere at 110 °C for 24 hours to obtain the catalyst precursor;

[0046] Step S1.5: Reduction: Grind the dried catalyst precursor and reduce it in a 10 vol% H2 atmosphere for 5 hours to obtain the ketonization reaction catalyst.

[0047] The catalyst composition of this example is shown in Table 1 (FAF: fly ash):

[0048] Table 1

[0049]

[0051] Example 2

[0052] This example is a comparative experiment of Example 1. Compared with Example 1, the difference is only that MnCl2 in Example 1 is not added, and the steps are adjusted as follows:

[0053] Precipitation: At room temperature, slowly dropwise add 2 mol / L NaOH solution to the solution (2 mL / min) until the pH value of the solution reaches 10. During the dropping process, the stirring speed is 300 r / min.

[0054] Other conditions are the same as those in Example 1, and the catalyst composition of this example is shown in Table 1.

[0055] Example 3

[0056] This example is a comparative experiment between Example 1 and Example 2. Compared with Example 1, the difference is that steps (1.1 - 1.3) in Example 1 are adjusted as follows:

[0057] (1) None;

[0058] (2) Preparation of filtrate: According to the composition of the fly ash catalyst, water-soluble chloride precursors of each metal are dissolved in 10 g of deionized water in corresponding proportions, and five solutions are prepared for comparison using a bottom-up method, namely FeCl3 + MgCl2, FeCl3 + MgCl2 + AlCl3, FeCl3 + MgCl2 + AlCl3 + CaCl2, FeCl3 + MgCl2 + AlCl3 + CaCl2 + MnCl2, FeCl3 + MgCl2 + AlCl3 + CaCl2 + MnCl2 + TiCl4;

[0059] (3) Precipitation: At room temperature, 2 mol / L NaOH solution is slowly added dropwise (2 mL / min) to the solution until the pH value of the solution reaches 10. During the addition process, the stirring speed is 300 r / min.

[0060] The remaining conditions are the same as those in Example 1, and the sample composition of this example is shown in Table 1.

[0061] Test Example 1:

[0062] This experiment aims to verify the application performance of the catalyst in the present invention for the ketonization reaction of acetic acid to prepare acetone. 200 mg of the samples obtained from Example 1, Example 2, and Example 3 are taken. Subsequently, at a temperature of 275 - 400 °C, 0.5 vol% acetic acid is introduced at a N2 flow rate of 200 mL / min. The experimental results show that the fly ash catalyst added with Mn exhibits high reaction activity at low temperatures (see Figure 2 ); meanwhile, various elements in the fly ash can promote the catalytic activity (see Figure 3 ), and compared with the catalyst synthesized from pure reagents, the fly ash catalyst shows better performance; under the low-temperature reaction conditions of 300 °C, for the fly ash catalyst added with Mn, the specific activity of its acetic acid ketonization reaction is 1.26 mmol·g -1 ·min -1 , and the corresponding turnover frequency of each acid site is 2.21 min-1 (see Table 2), which is better than other highly active catalysts reported in the literature. The comparison of the ketonization test results of Test Example 1 and the literature reports is shown in Table 2:

[0063] Table 2

[0064]

[0065]

[0067] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for extracting ketonization catalyst from high-speed iron solid waste, characterized in that: The process includes the following steps: Step S1.1: pretreatment: soaking the high-speed iron solid waste fly ash in deionized water to remove soluble substances therein, and then performing deionized water washing and drying pretreatment; Step S1.2: pickling: subjecting the pretreated high-speed railway solid waste fly ash to a hydrochloric acid pickling reaction, filtering and collecting the filtrate; Step S1.3: Precipitation: Add a certain amount of MnCl2 to the obtained filtrate, and then drop an alkaline solvent into the filtrate under stirring until the pH value reaches 6-10; Step S1.4: separation: performing solid-liquid separation on the precipitated mixed liquid, and the obtained solid is the catalyst precursor after drying; Step S1.5: Reduction: The catalyst precursor is ground and then subjected to reduction treatment to obtain a ketonization reaction catalyst.

2. The method for extracting ketonization catalyst from high-speed iron solid waste according to claim 1, characterized in that: In the step S1.1, the volume ratio of high-speed railway solid waste fly ash to deionized water is 1:10, and the soaking time is 24 hours.

3. The method for extracting ketonization catalyst from high-speed iron solid waste according to claim 1, characterized in that: In the step S1.1, the pretreatment condition is 110° C. for 24 hours.

4. The method for extracting ketonization catalyst from high-speed iron solid waste according to claim 1, characterized in that: In the step S1.2, the mass ratio of high-speed rail solid waste fly ash to hydrochloric acid is 1:2, and the reaction conditions are 70° C. and 2 hours.

5. The method for extracting ketonization catalyst from high-speed iron solid waste according to claim 1, characterized in that: In step S1.3, the alkaline solvent is NaOH or Na2CO3, and its concentration is 1-2 mol / L.

6. The method for extracting ketonization catalyst from high-speed iron solid waste according to claim 1, characterized in that: In step S1.4, the specific method of solid-liquid separation is: after centrifugation at 8000-10000 r / min for 10 minutes, the supernatant is poured out, deionized water is added to the precipitate and ultrasonic treatment is performed for 10 minutes, and then centrifugation is performed again, and this process is repeated four times.

7. The method for extracting ketonization catalyst from high-speed iron solid waste according to claim 1, characterized in that: In step S1.5, the reduction conditions are: 5-10 vol% H2 or CO, 2-5 hours.

8. A reaction process for extracting ketonization catalyst from high-speed iron solid waste to prepare acetone according to any one of claims 1 to 7, characterized in that: The process includes the following steps: Step S2.1: Raw material vaporization: First, acetic acid is introduced into the raw material vaporizer and vaporized by heating with high-pressure steam to ensure that the raw material entering the reactor is in a gaseous state, thereby improving the reaction efficiency and uniformity; Step S2.2: Shell-and-tube constant temperature packed bed reactor: The gasified acetic acid is introduced into the shell-and-tube constant temperature packed bed reactor, wherein the ketonization reaction catalyst is formed by tabletting and uniformly filled in the shell-and-tube constant temperature packed bed reactor, and the outside of the shell-and-tube constant temperature packed bed reactor utilizes pressurized steam or molten salt to circulate to provide the required heat to meet the heat absorption requirement of the acetic acid ketonization reaction, and the shell-side medium mode of axial shell-and-tube flow is used to make the shell-side fluid flow in parallel in the shell-and-tube direction, so that the flow is uniform, thereby reducing the risk of sintering and deactivation of the ketonization reaction catalyst due to local overheating; Step S2.3: The high-pressure steam used to heat the tubular constant temperature packed bed reactor enters the acetic acid raw material vaporizer after heat exchange to vaporize the acetic acid, thereby realizing the secondary utilization of heat energy; Step S2.4: Product separation and circulation: The product coming out of the shell-and-tube constant temperature packed bed reactor enters the condenser, and is condensed by cooling water. After passing through the gas-liquid separation tank, acetone and CO2 are separated, and the separated unreacted acetic acid and product water enter the shell-and-tube constant temperature packed bed reactor again to form a circulation system to improve the utilization rate of raw materials.

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