Method for producing hydrocyanic acid by using purge gas generated in pressure swing adsorption nitrogen production process

Abstract

The invention relates to a method for producing hydrocyanic acid by using purge gas generated in a pressure swing adsorption nitrogen production process, which comprises the following steps: S1, carrying out gas-solid separation on the purge gas to obtain purified gas containing oxygen; s2, methane, ammonia gas and purified gas are used as raw materials, under the action of a catalyst, hydrocyanic acid is prepared through an ammoxidation reaction, and purge gas is purge gas generated in the pressure swing adsorption nitrogen making process. The purge gas generated in the pressure swing adsorption nitrogen preparation process is used for replacing air to produce hydrocyanic acid by adopting an Andrusher method, so that the raw material ratio (for example, the use amount of methane in the raw materials) can be effectively reduced, the reaction temperature and the byproduct generation amount can be reduced, the product purity can be improved, the synthesis efficiency and the economic benefit of hydrocyanic acid can be improved, and valuable utilization of waste gas can be realized; the method has obvious economic benefits and environmental benefits; and meanwhile, the oxygen content in the oxygen raw material gas is increased, and the consumption of methane in the raw material and the reaction temperature are reduced by utilizing the combustion-supporting effect of oxygen, so that the production cost is further reduced.

Description

Technical Field

[0001] The present application relates to the field of chemical technology, and in particular to a method for producing hydrocyanic acid by utilizing purge gas generated in a nitrogen production process by pressure swing adsorption. Background Art

[0002] Hydrocyanic acid, also known as hydrogen cyanide, has a molecular formula of HCN and a bitter almond flavor. It is a highly toxic chemical. Due to its low boiling point (26.5°C), it is gaseous or liquid at room temperature, has a high vapor pressure, and is very easy to diffuse. Hydrocyanic acid is an important chemical raw material that can be used to synthesize fine chemicals such as acetone hydroalcohol, anilinoacetonitrile, triethyl orthoformate, cyanuric chloride, hydroxyacetonitrile, methionine, tert-butylamine, etc. It is widely used in organic glass, medicine, pesticides, dyes, food, feed, electroplating, metallurgy, polymers, mining, rubber, cosmetics, fertilizers and other fields.

[0003] In the actual production process, the synthesis of hydrocyanic acid generally adopts the Androsov method (also known as the Androsov method), that is, methane, ammonia and air (or oxygen) are used as raw materials, and the intermediate hydrocyanic acid gas is quickly reacted at high temperature under the catalytic action of platinum / rhodium / palladium alloy, and liquid hydrocyanic acid (purity ≥ 99.5%) is obtained by absorption. This method has strict requirements on the purity and proportion of raw materials, and usually requires a large amount of air as an oxygen source. However, the introduction of air will not only bring a large amount of inert gases such as nitrogen, increase the complexity and separation difficulty of the reaction system, but also consume more energy for heating and compressing these excess gases. And increase the cost of raw materials, the use of a large amount of air will consume more energy, indirectly lead to more carbon dioxide emissions, and have adverse effects on the environment. At the same time, the purity of the obtained hydrocyanic acid needs to be further improved.

[0004] Patent document with publication number CN103086400A discloses an environmentally friendly and clean process for producing hydrocyanic acid derivatives using purge gas. The solution uses purge gas as a methane source to produce hydrocyanic acid through the Angle method. However, the purity and yield of the product need to be further improved when using this method to produce hydrocyanic acid. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for producing hydrocyanic acid using the purge gas generated in the process of nitrogen production by pressure swing adsorption, so as to reduce the cost of raw materials, reduce the impact on the environment, and further improve the purity of hydrocyanic acid.

[0006] To achieve the above objectives, the scheme of this application is as follows:

[0007] The present invention provides a method for producing hydrocyanic acid by utilizing the purge gas generated in a nitrogen production process by pressure swing adsorption, comprising the following steps:

[0008] S1. Performing gas-solid separation on the purge gas to obtain purified gas, wherein the purified gas contains oxygen;

[0009] S2. Using methane, ammonia and the purified gas as raw materials, preparing the hydrocyanic acid by ammonia oxidation reaction in the presence of a catalyst;

[0010] The purge gas is the purge gas generated in the process of nitrogen production by pressure swing adsorption.

[0011] It should be noted that, in the present application, gas-solid separation can be performed by filtration to remove solid impurities entrained in the purge gas.

[0012] Optionally, in the purified gas in step S1, the volume content of oxygen is 25%-40%, preferably 30%-40%.

[0013] Optionally, in step S2, the volume ratio of methane, ammonia and purified gas is 0.8-1.0:1.0:1.2-2.0, preferably 0.9-1.0:1.0:1.2-2.0.

[0014] Optionally, in step S2, the catalyst is selected from a binary catalyst platinum / rhodium alloy or a platinum / palladium alloy or a ternary catalyst platinum / rhodium / palladium alloy.

[0015] Optionally, in the catalyst of step S2, the mass content of platinum is 90wt%-93wt%, preferably 92wt%-93wt%.

[0016] Optionally, in step S2, the temperature of the ammoxidation reaction is 900-1050°C, preferably 950-1050°C.

[0017] Optionally, in step S2, the pressure of the ammoxidation reaction is 0.03-0.06 MPa, preferably 0.04-0.06 MPa.

[0018] Optionally, in step S2, after the ammoxidation reaction, a purification step is also included.

[0019] Optionally, the purification step comprises deamination and dedoping.

[0020] Optionally, deamination is carried out using a sulfuric acid solution.

[0021] It should be noted that, in the present application, the concentration of the sulfuric acid solution is 75-90%, preferably 80-88%.

[0022] Optionally, the deamination temperature is 50-100°C, preferably 60-80°C.

[0023] Beneficial effects of the present invention:

[0024] The present application uses the purge gas generated in the process of nitrogen production by pressure swing adsorption to replace air and adopts the Angle method to produce hydrocyanic acid, which can effectively reduce the raw material ratio (for example, reduce the amount of methane in the raw material), reduce the reaction temperature and the amount of by-products generated, improve the product purity, improve the synthesis efficiency and economic benefits of hydrocyanic acid, realize the valuable utilization of waste gas, and have significant economic and environmental benefits.

[0025] The present application uses the purge gas generated in the process of nitrogen production by pressure swing adsorption to replace air and adopts the Angle method to produce hydrocyanic acid, thereby increasing the oxygen content in the oxygen raw gas, utilizing the combustion-supporting effect of oxygen, reducing the amount of methane in the raw material and the reaction temperature, and further reducing the production cost.

[0026] The present invention uses the purge gas generated in the process of nitrogen production by pressure swing adsorption to replace air and adopts the Angle method to produce hydrocyanic acid, thereby reducing waste gas emissions and reducing adverse impacts on the environment.

[0027] The present invention uses the purge gas generated in the process of nitrogen production by pressure swing adsorption to replace air and adopts the Angle method to produce hydrocyanic acid, which can eliminate the use of equipment in the air production system and reduce equipment costs and equipment space.

[0028] The present application provides a new method and idea for the synthesis of hydrocyanic acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0030] Figure 1 This is a process flow chart of this application. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, in this application, the term "wt%" refers to the mass percentage.

[0032] An embodiment of the present invention provides a method for producing hydrocyanic acid using the purge gas generated in a nitrogen production process by pressure swing adsorption. The method for producing hydrocyanic acid using the purge gas generated in a nitrogen production process by pressure swing adsorption comprises the following steps:

[0033] S1. Performing gas-solid separation on the purge gas to obtain purified gas, wherein the purified gas contains oxygen, and the volume content of oxygen in the purified gas is 30%-40%;

[0034] S2. Using methane, ammonia and purified gas as raw materials, in the presence of a catalyst, hydrocyanic acid is prepared by ammoxidation reaction, wherein the volume ratio of methane, ammonia and purified gas is 0.8-1.0:1.0:1.2-2.0, and the catalyst is selected from a binary catalyst platinum / rhodium alloy or a platinum / palladium alloy or a ternary catalyst platinum / rhodium / palladium alloy, wherein the mass content of platinum in the catalyst is 92wt%-93wt%, the temperature of the ammoxidation reaction is 950-1050°C, and the pressure of the ammoxidation reaction is 0.03-0.06MPa, preferably 0.04-0.08MPa;

[0035] The purge gas is the purge gas generated during the pressure swing adsorption nitrogen production process.

[0036] In another embodiment of the present invention, in step S2, after the ammoxidation reaction, a purification step is further included, and the purification includes deamination and de-impurity, and the deamination temperature is 60-80°C.

[0037] In the following description, numerous details are discussed to provide a more thorough explanation of embodiments of the present invention; however, it is apparent to one skilled in the art that embodiments of the present invention may be practiced without these specific details.

[0038] Example 1

[0039] like Figure 1 As shown, the present application provides a method for producing hydrocyanic acid using the purge gas generated in the process of nitrogen production by pressure swing adsorption, and the specific steps are as follows:

[0040] S1. Collect the purge gas generated in the process of nitrogen production by pressure swing adsorption, filter the purge gas generated in the process of nitrogen production by pressure swing adsorption (i.e., gas-solid separation) to remove solid impurities entrained in the purge gas, and obtain a purified gas with an oxygen volume content of 30% (detected by an oxygen content detector);

[0041] S2. methane (methane content is 99% by volume), ammonia (ammonia content is 99.5% by volume) and purge gas are sent into a fixed bed reactor (i.e., HCN reactor) in a volume ratio of 1.0:1.0:2.0, a platinum / rhodium catalyst (mass content of platinum is 93wt%) is loaded, the reaction temperature is set to 1050° C., the reaction pressure is set to 0.05MPa, and methane (volume content is 99%), ammonia (volume content is 99.5%) and oxygen in the purge gas undergo ammoxidation reaction under the catalytic action of the platinum / rhodium catalyst;

[0042] S3. A sulfuric acid solution with a concentration of 85% (the sulfuric acid solution is located in the deamination system, and the deamination system uses an acid absorption tower) is used to deaminize the system after the ammonia oxidation reaction to obtain a product, hydrocyanic acid.

[0043] The yield of hydrocyanic acid was calculated according to the formula yield (%) = molar amount of hydrocyanic acid / molar amount of ammonia feed × 100%, and the purity of hydrocyanic acid in the product was tested by chromatography. The results are shown in Table 1;

[0044] The energy consumption is calculated according to the formula comprehensive energy consumption = total amount of various energy consumed by hydrocyanic acid minus total output energy, and the results are shown in Table 1;

[0045] The energy consumption production cost is calculated according to the formula production cost = direct cost (including energy consumption, manpower, fuel and maintenance) + indirect cost (including management expenses, equipment depreciation and amortization, insurance expenses and taxes). The results are shown in Table 1.

[0046] Example 2

[0047] like Figure 1 As shown, the present application provides a method for producing hydrocyanic acid using the purge gas generated in the process of nitrogen production by pressure swing adsorption, and the specific steps are as follows:

[0048] S1. Collect the purge gas generated in the process of nitrogen production by pressure swing adsorption, filter the purge gas generated in the process of nitrogen production by pressure swing adsorption (i.e., gas-solid separation) to remove solid impurities entrained in the purge gas, and obtain a purified gas with an oxygen volume content of 35% (detected by an oxygen content detector);

[0049] S2. methane (methane content of 99% by volume), ammonia (ammonia content of 99.5% by volume) and purge gas are sent into a fixed bed reactor (i.e., HCN reactor) in a volume ratio of 0.9:1.0:1.5, a platinum / rhodium catalyst (mass content of platinum is 93wt%) is loaded, the reaction temperature is set to 1000° C., the reaction pressure is set to 0.05MPa, and methane (volume content is 99%), ammonia (volume content is 99.5%) and oxygen in the purge gas undergo ammoxidation reaction under the catalytic action of the platinum / rhodium catalyst;

[0050] S3. Deamination treatment is performed on the system after the ammoxidation reaction using a sulfuric acid solution with a concentration of 85% to obtain a product, hydrocyanic acid.

[0051] The yield of hydrocyanic acid was calculated according to the formula yield (%) = molar amount of hydrocyanic acid / molar amount of ammonia feed × 100%, and the purity of hydrocyanic acid in the product was tested by chromatography. The results are shown in Table 1;

[0052] The energy consumption is calculated according to the formula comprehensive energy consumption = total amount of various energy consumed by hydrocyanic acid minus total output energy, and the results are shown in Table 1;

[0053] The energy consumption production cost is calculated according to the formula production cost = direct cost (including energy consumption, manpower, fuel and maintenance) + indirect cost (including management expenses, equipment depreciation and amortization, insurance expenses and taxes). The results are shown in Table 1.

[0054] That is, the difference between this embodiment and embodiment 1 is that the volume content of oxygen in the purified gas is 35%, and the volume ratio of methane (volume content is 99%), ammonia (volume content is 99.5%) and purified gas is 0.9:1.0:1.5.

[0055] Example 3

[0056] like Figure 1 As shown, the present application provides a method for producing hydrocyanic acid using the purge gas generated in the process of nitrogen production by pressure swing adsorption, and the specific steps are as follows:

[0057] S1. Collect the purge gas generated in the process of nitrogen production by pressure swing adsorption, filter the purge gas generated in the process of nitrogen production by pressure swing adsorption (i.e., gas-solid separation) to remove solid impurities entrained in the purge gas, and obtain a purified gas with an oxygen volume content of 35% (detected by an oxygen content detector);

[0058] S2. methane (volume content is 99.3%), ammonia (volume content is 99.4%) and purified gas are sent into a fixed bed reactor (i.e., HCN reactor) according to a volume ratio of 0.9:1.0:1.5, a platinum / rhodium catalyst (mass content of platinum is 92wt%) is loaded, the reaction temperature is set to 1050° C., the reaction pressure is set to 0.05MPa, and methane (volume content is 99%), ammonia (volume content is 99.5%) and oxygen in the purified gas undergo ammoxidation reaction under the catalytic action of the platinum / rhodium catalyst;

[0059] S3. Deamination treatment is performed on the system after the ammoxidation reaction using a sulfuric acid solution with a concentration of 85% to obtain a product, hydrocyanic acid.

[0060] The yield of hydrocyanic acid was calculated according to the formula yield (%) = molar amount of hydrocyanic acid / molar amount of ammonia feed × 100%, and the purity of hydrocyanic acid in the product was tested by chromatography. The results are shown in Table 1;

[0061] The energy consumption is calculated according to the formula comprehensive energy consumption = total amount of various energy consumed by hydrocyanic acid minus total output energy, and the results are shown in Table 1;

[0062] The energy consumption production cost is calculated according to the formula production cost = direct cost (including energy consumption, manpower, fuel and maintenance) + indirect cost (including management expenses, equipment depreciation and amortization, insurance expenses and taxes). The results are shown in Table 1.

[0063] That is, the difference between this embodiment and embodiment 1 is that the volume content of oxygen in the purified gas is 35%, the purity of methane is 99.3%), the purity of ammonia is 99.4%), and the volume ratio of methane (volume content is 99%), ammonia (volume content is 99.5%) and purified gas is 0.9:1.0:1.5.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is:

[0066] Air is used instead of purified gas, and the air is transported by a reciprocating compressor. The temperature of the compressed air is 180°C. Before the compressed air is sent to the fixed bed reactor, the compressed air is decompressed (the pressure of the compressed air is 0.25MPa, which is much greater than the pressure of the ammonia oxidation reaction, and the volume content of oxygen in the decompressed air is 20%). In addition, the air is transported by a reciprocating compressor, and the air flow is unstable. An air buffer tank needs to be added to the air inlet pipeline; the volume ratio of methane (the volume content of methane is 99%), ammonia (the volume content of ammonia is 99.5%) and decompressed air is 1.2:1.0:6.0; the reaction temperature is set to 1150°C.

[0067] The yield of hydrocyanic acid was calculated according to the formula yield (%) = molar amount of hydrocyanic acid / molar amount of ammonia feed × 100%, and the purity of hydrocyanic acid in the product was tested by chromatography. The results are shown in Table 1;

[0068] The energy consumption is calculated according to the formula comprehensive energy consumption = total amount of various energy consumed by hydrocyanic acid minus total output energy, and the results are shown in Table 1;

[0069] The energy consumption production cost is calculated according to the formula production cost = direct cost (including energy consumption, manpower, fuel and maintenance) + indirect cost (including management expenses, equipment depreciation and amortization, insurance expenses and taxes). The results are shown in Table 1.

[0070] Comparative Example 2

[0071] The difference between this comparative example and Example 2 is:

[0072] Air is used instead of purified gas. The air is transported by a large air compressor. The air undergoes multi-stage compression, cooling and purification to obtain purified air (oxygen content is 20% by volume). The volume ratio of methane (volume content is 99.3%), ammonia (volume content is 99.4%) and purified air is 1.3:1.0:7.0; the reaction temperature is set to 1100°C.

[0073] The yield of hydrocyanic acid was calculated according to the formula yield (%) = molar amount of hydrocyanic acid / molar amount of ammonia feed × 100%, and the purity of hydrocyanic acid in the product was tested by chromatography. The results are shown in Table 1;

[0074] Energy consumption is calculated according to the formula energy consumption = sum of the products of the mass of each energy consumed * unit price of the corresponding energy - (total output energy * unit price of the corresponding energy * unit price of the corresponding energy), and the results are shown in Table 1;

[0075] The energy consumption production cost is calculated according to the formula production cost = direct cost (including energy consumption, manpower, fuel and maintenance) + indirect cost (including management expenses, equipment depreciation and amortization, insurance expenses and taxes). The results are shown in Table 1.

[0076] Table 1 Test results

[0077] Group Yield, % purity,% Energy consumption, yuan / t Cost, yuan / t Example 1 90 7.5 7150 7750 Example 2 95 8.5 7100 7700 Example 3 90 7.8 7125 7725 Comparative Example 1 80 6.1 7600 8150 Comparative Example 2 82 5.5 7700 8100

[0078] As shown in Table 1, compared with Comparative Example 1 (using air as the oxygen source), the yield and purity of Example 1 (using the purge gas generated in the process of nitrogen production by pressure swing adsorption as the oxygen source) are significantly increased, and the energy consumption and cost are significantly reduced; compared with Comparative Example 2 (using air as the oxygen source), the yield and purity, energy consumption and cost of Example 2 (using the purge gas generated in the process of nitrogen production by pressure swing adsorption as the oxygen source) are significantly reduced. The results show that the present application uses the purge gas generated in the process of nitrogen production by pressure swing adsorption instead of air to produce hydrocyanic acid by Angle method, which can effectively reduce the raw material ratio (for example, reduce the amount of methane in the raw material), reduce the reaction temperature and the amount of by-products generated, improve the product purity, improve the synthesis efficiency and economic benefits of hydrocyanic acid, realize the valuable utilization of waste gas, and have significant economic and environmental benefits.

[0079] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for producing hydrocyanic acid using the purge gas generated in a nitrogen production process by pressure swing adsorption, comprising the following steps: S1. Performing gas-solid separation on the purge gas to obtain purified gas, wherein the purified gas contains oxygen; S2. Using methane, ammonia and the purified gas as raw materials, preparing the hydrocyanic acid by ammonia oxidation reaction in the presence of a catalyst; The invention is characterized in that the purge gas is the purge gas generated in the process of nitrogen production by pressure swing adsorption.

2. The method for producing hydrocyanic acid by utilizing the purge gas generated in the nitrogen production process by pressure swing adsorption according to claim 1, characterized in that: In the purified gas of step S1, the volume content of oxygen is 25%-40%.

3. The method for producing hydrocyanic acid by utilizing the purge gas generated in the nitrogen production process by pressure swing adsorption as claimed in claim 2, characterized in that: In step S2, the volume ratio of methane, ammonia and purified gas is 0.8-1.0:1.0:1.2-2.

0.

4. The method for producing hydrocyanic acid by utilizing the purge gas generated in the nitrogen production process by pressure swing adsorption according to claim 1, characterized in that: In step S2, the catalyst is selected from a binary catalyst platinum / rhodium alloy or a platinum / palladium alloy or a ternary catalyst platinum / rhodium / palladium alloy.

5. The method for producing hydrocyanic acid by utilizing the purge gas generated in the nitrogen production process by pressure swing adsorption as claimed in claim 4, characterized in that: In the catalyst of step S2, the mass content of platinum is 90wt%-93wt%.

6. The method for producing hydrocyanic acid by utilizing the purge gas generated in the nitrogen production process by pressure swing adsorption as claimed in claim 1, characterized in that: In step S2, the temperature of the ammoxidation reaction is 900-1050°C.

7. The method for producing hydrocyanic acid by utilizing the purge gas generated in the nitrogen production process by pressure swing adsorption as claimed in claim 1, characterized in that: In step S2, the pressure of the ammoxidation reaction is 0.03-0.06 MPa.

8. The method for producing hydrocyanic acid by utilizing the purge gas generated in the nitrogen production process by pressure swing adsorption as claimed in claim 1, characterized in that: In step S2, after the ammoxidation reaction, a purification step is also included.

9. The method for producing hydrocyanic acid by utilizing the purge gas generated in the nitrogen production process by pressure swing adsorption as claimed in claim 8, characterized in that: The purification step includes deamination and de-doping.

10. The method for producing hydrocyanic acid by utilizing the purge gas generated in the nitrogen production process by pressure swing adsorption according to claim 9, characterized in that: The deamination temperature is 50-100°C.

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