CN115400549B - Morpholine cyclic amine desulfurizing agent with high regeneration cycle performance and preparation method thereof - Google Patents

Abstract

The invention provides a morpholine cyclic amine desulfurizer with high regeneration cycle performance and a preparation method thereof. The morpholine cyclic amine desulfurizer is prepared by mixing N-(2-hydroxyethyl)morpholine (HEM) as a solute and polyethylene glycol dimethyl ether (NHD) as a solvent. The desulfurizer provided by the present invention not only has a good absorption effect on _SO2 , which is significantly higher than the organic liquid desulfurizers such as the commercially available industrial Cansolv amine solution, but also has excellent absorption effect on multiple cycles of _SO2 under higher concentration conditions. The preparation method thereof has the characteristics of low cost and process steps suitable for continuous production, and has the prospect of industrial production.

Description

Morpholine cyclic amine desulfurizer with high regeneration cycle performance and preparation method thereof

Technical Field

The invention belongs to the field of desulfurizers for industrial flue gas and relates to a morpholine cyclic amine desulfurizer with high regeneration cycle performance and a preparation method thereof.

Background technique

China is a country rich in coal, poor in oil and little in gas. It is also a country with extremely strong energy demand. China's coal production and demand are huge, both of which are the highest in the world. Traditional energy sources such as coal will produce a variety of air pollutants during the combustion process, including sulfur dioxide (molecular formula SO ₂ ). SO ₂ emitted into the atmosphere will cause acid rain pollution, causing plants to develop poorly and grow slowly, and then quickly wither and die, and endanger human health and the survival of various animals and plants; acid rain will also corrode buildings, mechanical equipment and municipal facilities, causing significant economic losses, and may also cause other safety problems. In addition, SO ₂ in the atmosphere can also be oxidized to SO ₃ , and finally form sulfuric acid mist, causing more serious harm.

According to the survey, in 2020, China's total _SO2 emissions reached 3.182 million tons, of which industrial sources accounted for 2.532 million tons, accounting for nearly 80%. In view of the severe _SO2 emissions in China and the market demand for economic development, the state and industrial production enterprises have put forward higher requirements for industrial flue gas desulfurization technology. In general, the commonly used means of desulfurization technology at present are wet desulfurization, (semi-) dry desulfurization, ionic liquid desulfurization, organic amine desulfurization, etc. Among them, the wet desulfurization process has the characteristics of fast reaction rate and high desulfurization rate, but it will also produce a large amount of wastewater and waste liquid. The proper disposal of wastewater and the problem of secondary pollution are also the main problems in current industrial applications; the by-product of the dry desulfurization process is solid, which is conducive to comprehensive application, but the reaction rate is relatively slow and the desulfurization rate is low; in recent years, the commonly used semi-dry desulfurization absorbent has a high utilization rate and no wastewater is generated, but there are also problems such as high content of smoke particles after desulfurization, which limits its promotion and use in actual environments; ionic liquid desulfurization has the advantages of mild conditions, simple operation, short time consumption and low energy consumption. Among them, organic amine desulfurization, as an emerging application of ionic liquids, has attracted widespread attention due to its high absorption rate, easy recycling, economic and environmental protection, etc. However, due to the difficulties in preparation and recycling, this technology currently has no obvious advantages in terms of economy, which is also a key issue hindering the development and application of this type of desulfurization technology.

Specifically, as an absorption technology, the structure and composition of the absorbent of the organic amine method will directly determine the absorption and regeneration performance. There are four commonly used types of organic amine desulfurizers: chain monoamines, chain diamines, cyclic amines and mixed amines. Among them, chain monoamines are easily degraded and deteriorated, difficult to regenerate, and have almost no selectivity for the absorption of _SO2 ; chain diamines solve the problem of high energy consumption for the regeneration of chain monoamines, but the cost of the patented amine liquid used is relatively high, and there is still a lot of room for improvement. At present, there are many reports on cyclic amines represented by piperazine (PZ) and its derivatives. Compared with diamines such as alcoholamines and EDA, they have better absorption capacity. Chinese patent CN202011025636.3 discloses an organic amine desulfurizer and its preparation method and application, which adds a composite antioxidant inhibitor to piperazine organic amines in order to improve the sulfur dioxide recovery rate and reduce the loss of desulfurizers. Chinese patent CNCN201610745489.4 discloses a composite piperazine organic amine desulfurizer, which also improves the absorption-desorption comprehensive performance of the desulfurizer by adding aliphatic amines, aromatic amines, absorbents, additives, etc. to the dihydroxyalkyl piperazine system. However, in practical applications, their desorption rate is still relatively low, and the high regeneration energy consumption has limited market promotion.

In view of the above situation, it is an urgent problem to be solved in the current engineering application of removing SO ₂ from flue gas to prepare a SO ₂ organic liquid desulfurizer with high SO ₂ absorption efficiency, good regeneration cycle performance and low cost.

Summary of the invention

In order to solve the problems raised in the above background technology, the present invention provides a morpholine cyclic amine desulfurizer with high regeneration cycle performance and a preparation method thereof. It not only has a good absorption effect on _SO2 , which is significantly higher than the commercially available industrial Cansolv amine liquid and other organic liquid desulfurizers, but also has excellent absorption effect on _SO2 under high concentration conditions for multiple cycles. Its preparation method has the characteristics of low cost and process steps suitable for continuous production, and has prospects for industrial production.

To achieve the above objectives, the present invention is implemented by adopting a technical solution consisting of the following technical measures.

In one aspect, the present invention provides a morpholine-based cyclic amine desulfurizer with high regeneration cycle performance, which is prepared by mixing N-(2-hydroxyethyl)morpholine (HEM) as a solute and polyethylene glycol dimethyl ether (NHD) as a solvent.

The present invention is based on the inventor's research and discovery that in current technical literature, morpholine cyclic amines are mostly selected as an organic solvent for desulfurizers because of their desulfurization function and certain sulfur capacity, and are usually used as one of the alternative organic solvents in desulfurizers with alcohol reagents, ether reagents, sulfone reagents, etc.; or, under the premise of adding a small amount, they are used as enhancers or synergists of desulfurizers to improve the desulfurization and sulfur tolerance effects of the desulfurizer.

In the above research literature, the morpholine cyclic amines mentioned include morpholine, N-(2-hydroxyethyl)morpholine (HEM), N-formylmorpholine, N-methylmorpholine, etc. as the more mainstream choices.

However, the currently disclosed desulfurizer formulas with high desulfurization performance are basically prepared by compounding multiple components, or have a relatively complex preparation method, so as to ensure its excellent desulfurization performance, which invisibly increases the application cost of the desulfurizer. The industrial use of desulfurizers is usually based on high dosage and high consumption. Therefore, a large number of new desulfurizer patents can only exist in the laboratory verification stage and cannot be put into practical industrial applications. Based on the idea of reducing industrial costs, the inventors of the present invention designed experiments to verify whether morpholine cyclic amines can be used as the main desulfurization functional component of a single-component non-compound desulfurizer:

Through preliminary tests, it was found that when the organic solvent was selected as conventional sulfolane (SUL) (which has extremely low viscosity and saturated vapor pressure, and has extremely low absorption capacity for SO ₂ , thus not interfering with the test results), morpholine (MP), N-(2-hydroxyethyl)morpholine (HEM), N-formylmorpholine, and N-methylmorpholine all had good desulfurization adsorption capacity, among which morpholine had the strongest desulfurization adsorption capacity. N-(2-aminoethyl)morpholine (AEM), which was not mentioned in the above research literature, was also included in the designed test, and it was found that its desulfurization adsorption capacity was significantly poor, confirming the reason why it was not adopted in the desulfurization industry.

However, in the further regeneration cycle test of the desulfurizer, it was found that morpholine (MP) was difficult to regenerate through analytical heat, and its desulfurization adsorption performance was close to one-time, so it could not be used as the main desulfurization functional component of the desulfurizer that needs multiple regeneration cycles. N-(2-hydroxyethyl)morpholine (HEM), N-formylmorpholine, and N-methylmorpholine all showed better regeneration cycle performance, and the total sulfur absorption of the above three after 5 regeneration cycles was slightly different, among which N-(2-hydroxyethyl)morpholine (HEM) was only slightly better than N-formylmorpholine and N-methylmorpholine.

The preliminary experimental contents and conclusions of the above-mentioned designed experiments are recorded in the published paper by the inventor of the present invention (The absorption of _SO2 by morpholine cyclic amines with sulfolane as the solventfor flue gas[J].Journal of Hazardous Materials,2021,408:124462.).

Based on the above research findings, the inventors of the present invention conducted a large number of tests in the later stage of the experiment to further reduce the industrial production cost and improve the desulfurization performance of the desulfurizer when N-(2-hydroxyethyl)morpholine (HEM) is used as the solute, and obtained the best and most suitable organic solvent selection. In the experiment, the most widely used organic solvent in the current desulfurization technology was screened, and divalent acid ester solvents represented by dimethyl succinate (DMSu), dimethyl glutarate (DMG) and dimethyl adipate (DMA) were selected, ether reagents represented by polyethylene glycol dimethyl ether (NHD) and triethylene glycol monomethyl ether (TEM), sulfone reagents represented by dimethyl sulfoxide (DMSO) and cyclopentane (SUL), and alcohol reagents represented by ethanol (EtOH) and glycerol (Gly).

The above-mentioned organic solvents were used to prepare mixed solutions with N-(2-hydroxyethyl)morpholine (HEM) in the same concentration ratio. In the first desulfurization adsorption test, it was found that when propylene glycol (Gly), triethylene glycol monomethyl ether (TEM) and dimethyl sulfoxide (DMSO) were used as solvents, they all showed a first absorption capacity significantly higher than that of other organic solvents.

However, after counting the total sulfur absorption after five regeneration cycles, it was surprisingly found that when polyethylene glycol dimethyl ether (NHD) was used as a solvent, its total sulfur absorption after five regeneration cycles was significantly higher than that of other organic solvents. The sulfur absorption of several organic solvents with the highest initial absorption capacity during the five regeneration cycles showed a relatively obvious downward trend, and the total sulfur absorption was significantly lower than that of polyethylene glycol dimethyl ether (NHD); and triethylene glycol monomethyl ether (TEM), which is also an ether reagent, also had a significantly lower total sulfur absorption than polyethylene glycol dimethyl ether (NHD).

This accidental discovery is obviously of great benefit to the preparation and production of low-cost N-(2-hydroxyethyl)morpholine (HEM) single-component non-compound desulfurizer and its actual industrial application. In addition, through multiple regeneration cycle desulfurization tests, it can be clearly found that under the combination of N-(2-hydroxyethyl)morpholine (HEM) and polyethylene glycol dimethyl ether (NHD), the sulfur absorption in each regeneration cycle is more uniform and stable than other solvents, which fully demonstrates that it has better industrial application prospects.

In this article, the morpholine cyclic amine desulfurizer is prepared by mixing N-(2-hydroxyethyl)morpholine (HEM) as a solute and polyethylene glycol dimethyl ether (NHD) as a solvent. It should be emphasized that the morpholine cyclic amine desulfurizer of the present invention is obtained by mixing only N-(2-hydroxyethyl)morpholine (HEM) and polyethylene glycol dimethyl ether (NHD) to ensure its low industrial cost-effectiveness, and the solute is evenly dispersed to form a homogeneous solution, which is conducive to long-term preservation. Whether the addition of other additives/fillers/reinforcers to form a composite desulfurizer will affect the stability of its sulfur absorption amount in multiple regeneration cycles is not yet known, and may destroy its homogeneous properties.

In one of the technical solutions, the mass percentage of N-(2-hydroxyethyl)morpholine (HEM) as a solute in the morpholine-based cyclic amine desulfurizer is 20% to 50%.

It should be noted that, under the premise that the present invention provides the above-mentioned solute and solvent components, those skilled in the art can obtain a specific method for preparing the mixed solution by referring to the prior art through the conventional principles of mixed solutions. Therefore, the technical solutions provided below in the present invention do not mean the sole designation or limitation of the preparation method of the present invention.

The preparation method of the above-mentioned morpholine cyclic amine desulfurizer with high regeneration cycle performance mainly comprises the following steps:

(1) N-(2-hydroxyethyl)morpholine (HEM) as a solute and polyethylene glycol dimethyl ether (NHD) as a solvent are mixed to obtain a mixed solution;

(2) The mixed solution obtained in step (1) is stirred at room temperature or 20 to 40° C. to uniformly disperse N-(2-hydroxyethyl)morpholine, thereby obtaining a morpholine-based cyclic amine desulfurizer with high regeneration performance.

The morpholine cyclic amine mixed absorbent finally prepared by the above technical scheme has a strong ability to absorb _SO2 in multiple cycles under high concentration conditions under the condition of a temperature window of 293.15K to 333.15K and a certain gas flow rate, and can achieve better results.

A preferred technical scheme is used to prepare a morpholine cyclic amine mixed absorbent. When the temperature is 293.15K and the gas flow rate is 700ml/min, under the condition of simulating a _SO2 concentration of 8580mg/ ^m3 in the flue gas, the first adsorption can reach 192.18mg/g, and the absorption capacity after 5 cycles can reach more than 4800mg/g.

The present invention has the following beneficial effects:

1. The morpholine cyclic amine desulfurizer provided by the present invention can achieve a considerable level of multiple cycle absorption capacity for _SO2 at higher concentration conditions at a certain temperature. The multiple reuse effect of the preferred technical solution is higher than that of the Cansolv amine solution that has been industrially applied under similar experimental conditions. In addition, under the condition that multiple flue gas components such as _SO2 , _NOx and _O2 coexist, it has excellent selectivity for the absorption of _SO2 , and the water in the wet flue gas has little effect on its absorption efficiency. It is particularly suitable for the absorption of _SO2- containing waste gas discharged by the steel sintering and pelletizing industries.

2. The morpholine cyclic amine desulfurizer absorbent provided by the present invention has high desulfurization efficiency, simple and reliable operation and maintenance, and good thermal and chemical stability of the absorbent; and at the same time, as a homogeneous liquid, it has the advantage of long-term storage.

3. The preparation method of the present invention has the characteristics of low cost and simple process steps. In addition, it has the advantages of low regeneration energy consumption and low energy consumption cost. It has good economic efficiency in engineering application and is lower in cost than traditional desulfurization methods. It has excellent market application prospects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bar chart comparing the first absorption capacity of SO ₂ in Example 1 of the present invention and Comparative Examples 1 to 8 in a desulfurization adsorption test.

FIG. 2 is a comparison chart of the SO ₂ absorption capacity of Example 1 of the present invention and Comparative Examples 1 to 8 after 5 regeneration cycles in the desulfurization adsorption test.

FIG3 is a comparison chart of the mass loss rate of the solution of Example 1 of the present invention and Comparative Examples 1 to 8 after 5 regeneration cycles in the desulfurization adsorption test.

FIG4 is a photograph showing that HEM-NHD-40 prepared in Example 1 of the present invention exhibits obvious stratification after absorbing SO ₂ .

Figure 5 is a FTIR comparison chart of the supernatant and lower layer liquid of HEM-NHD-40 prepared in Example 1 of the present invention before absorption and after the first absorption of _SO2 . In the figure, the top spectrum line corresponds to before absorption, the middle spectrum line corresponds to the supernatant after the first absorption _{of SO2} , and the bottom spectrum line corresponds to the lower layer liquid after the first absorption of _SO2 .

Figure 6 is a FTIR comparison chart of HEM-NHD-40 prepared in Example 1 of the present invention before absorption and after 5 regeneration cycles. In the figure, the top spectrum line corresponds to the HEM-NHD-40 before absorption, and the bottom spectrum line corresponds to the HEM-NHD-40 desorbed again after 5 regeneration cycles.

Figure 7 is the NMR spectra of HEM-NHD-40 prepared in Example 1 of the present invention before absorption and after 5 regeneration cycles. The left figure (a) is a 1H NMR spectrum, the top spectrum line corresponds to the HEM-NHD-40 before absorption, and the bottom spectrum line corresponds to the HEM-NHD-40 desorbed again after 5 regeneration cycles; the right figure (b) is a 13C NMR spectrum, the top spectrum line corresponds to the HEM-NHD-40 before absorption, and the bottom spectrum line corresponds to the HEM-NHD-40 desorbed again after 5 regeneration cycles.

FIG8 is a photograph showing that HEM-TEM-40 prepared in Comparative Example 6 of the present invention does not show delamination after absorbing SO ₂ .

FIG9 is a FTIR comparison chart of HEM-TEM-40 prepared in Comparative Example 6 of the present invention before absorption, after the first absorption of SO ₂ , and after 5 regeneration cycles. In the figure, the top spectrum corresponds to before absorption, the middle spectrum corresponds to after the first absorption of SO ₂ , and the bottom spectrum corresponds to HEM-TEM-40 desorbed again after 5 regeneration cycles.

Figure 10 is the NMR spectra of HEM-TEM-40 prepared in Comparative Example 6 of the present invention before absorption, after the first absorption of SO ₂ , and after 5 regeneration cycles. The left figure (a) is a 1H NMR spectrum, the top spectrum line corresponds to before absorption, the middle spectrum line corresponds to the first absorption of SO ₂ , and the bottom spectrum line corresponds to HEM-TEM-40 desorbed again after 5 regeneration cycles; the right figure (b) is a 13C NMR spectrum, the top spectrum line corresponds to before absorption, the middle spectrum line corresponds to the first absorption of SO ₂ , and the bottom spectrum line corresponds to HEM-TEM-40 desorbed again after 5 regeneration cycles.

FIG. 11 is a comparison chart of the SO ₂ absorption capacity of Examples 1 to 3 of the present invention after 5 regeneration cycles in repeated desulfurization adsorption tests.

FIG. 12 is a schematic flow chart of the SO ₂ absorption experiment in the test method of the present invention.

FIG. 13 is a schematic flow chart of the desorption SO ₂ experiment in the testing method of the present invention.

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously change or appropriately change and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention. Although it is believed that those of ordinary skill in the art fully understand the following terms, the following definitions are still stated to help illustrate the subject matter disclosed by the present invention.

In one aspect, the present invention provides a morpholine-based cyclic amine desulfurizer with high regeneration cycle performance, which is prepared by mixing N-(2-hydroxyethyl)morpholine (HEM) as a solute and polyethylene glycol dimethyl ether (NHD) as a solvent.

In this article, the morpholine cyclic amine desulfurizer is prepared by mixing N-(2-hydroxyethyl)morpholine (HEM) as a solute and polyethylene glycol dimethyl ether (NHD) as a solvent. It should be emphasized that the morpholine cyclic amine desulfurizer of the present invention is obtained by mixing only N-(2-hydroxyethyl)morpholine (HEM) and polyethylene glycol dimethyl ether (NHD) to ensure its low industrial cost-effectiveness, and the solute is evenly dispersed to form a homogeneous solution, which is conducive to long-term preservation. Whether the addition of other additives/fillers/reinforcers to form a composite desulfurizer will affect the stability of its sulfur absorption amount in multiple regeneration cycles is not yet known, and may destroy its homogeneous properties.

In one embodiment, the mass percentage of N-(2-hydroxyethyl)morpholine (HEM) as a solute in the quinoline cyclic amine desulfurizer is 1% to 99%, for example, 1%, 2%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98%, 99%.

In one preferred embodiment, the mass percentage of N-(2-hydroxyethyl)morpholine (HEM) as a solute in the morpholine cyclic amine desulfurizer is 20% to 50%, such as 21%, 22%, 24%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, 49%. Through comparative experiments, it is found that when the amount of solute added exceeds 50wt%, it will affect physical properties such as viscosity and hinder its absorption of _SO2 . It is further preferably 30% to 40%.

It should be noted that, under the premise that the present invention provides the above-mentioned solute and solvent components, those skilled in the art can obtain a specific method for preparing the mixed solution by referring to the prior art through the conventional principles of mixed solutions. Therefore, the technical solutions provided below in the present invention do not mean the sole designation or limitation of the preparation method of the present invention.

The preparation method of the above-mentioned morpholine cyclic amine desulfurizer with high regeneration cycle performance mainly comprises the following steps:

(1) N-(2-hydroxyethyl)morpholine (HEM) is used as a solute and polyethylene glycol dimethyl ether (NHD) is used as a solvent to prepare a mixed solution;

(2) The mixed solution obtained in step (1) is stirred at room temperature or 20 to 40° C. to uniformly disperse N-(2-hydroxyethyl)morpholine, thereby obtaining a morpholine-based cyclic amine desulfurizer with high regeneration performance.

In one embodiment, the stirring method in step (2) is mechanical stirring. Those skilled in the art may stir according to the common knowledge in the art, or refer to the conventional mechanical stirring methods for organic reagents in the chemical industry, for example, by using conventional industrial agitators such as propeller agitators, turbine agitators, paddle agitators, anchor agitators, etc.

In one embodiment, the stirring method in step (2) is magnetic stirring, and those skilled in the art can use the common knowledge in the art or refer to the conventional magnetic stirring method for organic reagents in chemical laboratories.

In one preferred embodiment, under the premise that the total mass of the reagent does not exceed 1 kg, the stirring method in step (2) is magnetic stirring, and the stirring is carried out at a rate of 200 to 400 r/min for more than 1 min, so that N-(2-hydroxyethyl)morpholine (HEM) is fully dissolved in polyethylene glycol dimethyl ether (NHD).

The present invention will be further explained in detail with reference to the following examples. However, it should be understood by those skilled in the art that these examples are provided for the purpose of illustration only and are not intended to limit the present invention.

Example

The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If the specific conditions are not specified in the examples, the conditions recommended by the normal conditions or manufacturers are carried out. If the manufacturers are not specified in the reagents or instruments used, they are all conventional products that can be obtained commercially. Unless otherwise specified, all amounts listed are described in weight percentage based on gross weight. The application should not be construed as being limited to the specific embodiments described.

1. Selection of reagents

The main experimental reagents and raw materials are shown in Table 1.

Table 1 Summary of experimental reagents and raw materials

Table1 The summary table of experimental reagents and raw materials.

2. Test Method

_SO2 absorption experiment:

According to the different absorption doses required for the experiment, two sizes of 5ml and 50ml Meng's washing bottles are selected to hold the desulfurizer samples used in the experiment. The stopper of the washing bottle is wrapped with raw tape to ensure airtightness. Then the empty washing bottle is weighed with a balance, and the mass is recorded as _M0 . A certain mass of solvent and solute is taken into the washing bottle with a rubber dropper, shaken and weighed with a balance, and the total mass is recorded as M _T.

The device flow chart of the _SO2 absorption experiment is shown in Figure 12. The required gas enters the mass flow controller from the gas cylinder through the pipeline to control the flow of each gas, and enters the gas mixing device to mix the gas, and the total gas flow is controlled to be 700ml/min. The pipeline is bypassed, and the mixed gas enters the flue gas analyzer directly after drying. The gas flow ratio is adjusted to stabilize the _SO2 concentration value of the flue gas analyzer within 2% of the required _SO2 concentration value. The sampled washing bottle is connected to the absorption experiment device and immersed in a digital constant temperature oil bath to control and stabilize the experimental temperature, and then the pipeline is switched back to the main line from the bypass. The experiment uses the bubbling method to blow the configured mixed gas into the washing bottle containing the mixed absorbent, and the Gasboard-3000PLUS flue gas analyzer is used to perform online detection of the _SO2 outlet concentration in the simulated flue gas. The absorption capacity of the absorbent can be calculated by the following formulas (4) and (5):

M＝M _T -M ₀ (4)

Desorption of _SO2 Experiment:

The flow chart of the device for the _SO2 desorption experiment is shown in Figure 13. After the absorption experiment is completed, the absorption liquid is desorbed under the conditions of a 353.15K oil bath and 700ml/min nitrogen purge. Considering that the _SO2 concentration generated by the absorption liquid at the beginning of desorption may exceed the range of the flue gas analyzer, the amount of _SO2 desorbed in each period of time is determined by hydrochloric acid titration. As shown in Figure 3, 30ml of NaOH standard solution of appropriate concentration is prepared to collect the _SO2 obtained by desorption. 3-5 drops of 30% _H2O2 solution need to be added to the NaOH standard solution to oxidize the sulfite formed. The solution in the _SO2 collection bottle is titrated with a certain concentration of HCl standard solution, and the amount of _SO2 desorbed _in a certain period of time is calculated using formulas (6) and (7).

On the basis of the above absorption and desorption experiments, absorption-desorption cycle experiments were carried out using the desulfurizers (mixed absorbents) of various embodiments and comparative examples, and five cycle absorption experiments were carried out under the condition that the absorption and desorption temperatures were constant.

Example 1, Comparative Examples 1 to 8

Example 1 and Comparative Examples 1 to 8 are respectively based on dibasic acid ester solvents represented by dimethyl succinate (DMSu), dimethyl glutarate (DMG) and dimethyl adipate (DMA), ether reagents represented by polyethylene glycol dimethyl ether (NHD) and triethylene glycol monomethyl ether (TEM), sulfone reagents represented by dimethyl sulfoxide (DMSO) and cyclopentane sulfone (SUL), and alcohol reagents represented by ethanol (EtOH) and glycerol (Gly) as solvents. Through comparative experiments, the desulfurizer prepared when N-(2-hydroxyethyl)morpholine (HEM) was used as the solute (40wt%) was studied in the desulfurization adsorption test ( _SO2 absorption experiment), the first absorption capacity of _SO2 and the total absorption capacity after 5 regeneration cycles.

The flue gas conditions simulated in the laboratory were: SO ₂ concentration = 8580 mg/m ³ , nitrogen as carrier gas, gas flow rate of 700 ml/min, reaction temperature of 293.15 K, and water content of 0%.

As shown in Figure 1, the first absorption capacity of _SO2 by desulfurizers with different solvents is different. When glycerol (Gly), triethylene glycol monomethyl ether (TEM), and dimethyl sulfoxide (DMSO) are used as solvents, they all show a significantly higher first absorption capacity than other organic solvents. The specific absorption data are shown in Table 2 below:

Table 2 List of the first SO ₂ absorption capacity of mixed absorbents

Serial number name SO ₂ absorption capacity (mg/g) Comparative Example 1 1 HEM-EtOH-40 80.84 Comparative Example 2 2 HEM-Gly-40 230.3 Comparative Example 3 3 HEM-DMSu-40 194.1 Comparative Example 4 4 HEM-DMG-40 177.57 Comparative Example 5 5 HEM-DMA-40 163.8 Example 1 6 HEM-NHD-40 196.73 Comparative Example 6 7 HEM-TEM-40 225.75 Comparative Example 7 8 HEM-DMSO-40 213.9 Comparative Example 8 9 HEM-SUL-40 192.18

As shown in FIG2 , among the total absorption capacities of the desulfurizers with different solvents after 5 regeneration cycles, it was surprisingly found that when polyethylene glycol dimethyl ether (NHD) was used as the solvent, its total sulfur absorption after 5 regeneration cycles was significantly higher than that of other organic solvents.

Table 3 Summary of total SO ₂ absorption after 5 regeneration cycles of mixed absorbent

Serial number name 5-cycle SO ₂ absorption capacity (mg) Comparative Example 1 1 HEM-EtOH-40 / Comparative Example 2 2 HEM-Gly-40 / Comparative Example 3 3 HEM-DMSu-40 4173.96 Comparative Example 4 4 HEM-DMG-40 3979.92 Comparative Example 5 5 HEM-DMA-40 3930.08 Example 1 6 HEM-NHD-40 5012.09 Comparative Example 6 7 HEM-TEM-40 4533.85 Comparative Example 7 8 HEM-DMSO-40 / Comparative Example 8 9 HEM-SUL-40 4317.45

As shown in FIG3 , the mass loss rates of the desulfurizers of different solvents after 5 regeneration cycles are compared. When polyethylene glycol dimethyl ether (NHD) is used as the solvent, the difference from the other solvents is not obvious.

Figure 4 shows that when polyethylene glycol dimethyl ether (NHD) is used as a solvent, an obvious stratification phenomenon (b) occurs after SO ₂ absorption. On this basis, the absorbent before reaction and the supernatant and lower layer liquid of the absorbent after reaction are characterized by FT-IR, as shown in Figures 5 and 6 of the specification. First of all, the weighted sum of the FTIR spectra of HEM and NHD is highly similar to that of HEM-NHD-40, and no new peaks are generated, indicating that NHD in the absorbent mainly acts as a physical solvent. Secondly, the absorption peaks at 455, 602 and 947 cm ^-1 are the characteristic absorption peaks of sulfite, and the molecular vibrations of S and O correspond to the molecular vibrations of S and O, indicating that the chemical reaction of the system components leads to SO ₂ absorption. More importantly, after 5 absorption-desorption cycles, the absorption peaks of HEM-NHD-40 have hardly changed, and the spectrum is almost exactly the same as before absorption, indicating that the HEM-NHD-40 absorbent has excellent regeneration performance, and the absorbent is highly regenerated after the absorption-desorption cycle. In the characterization of the absorbent 1H NMR and 13CNMR nuclear magnetic resonance after 5 absorption-desorption cycles, the δ phase difference values of each characteristic peak are almost all around 0.02 ppm, as shown in Figure 7 of the specification, which also shows that the HEM-NHD-40 structure has good recovery strength and excellent regeneration performance, which is completely consistent with the experimental results.

The same characterization as above was carried out for triethylene glycol monomethyl ether (TEM), which is also an ether reagent. As shown in Figure 8, the desulfurizer prepared by it did not delaminate after the desulfurization adsorption test. Based on the experiment, the absorbent was characterized by FT-IR before and after the reaction, as shown in Figure 9 of the specification. The weighted sum of the FTIR spectra of HEM and TEM is very similar to HEM-TEM-40, and no new peaks are generated, indicating that TEM is mainly a physical solvent in the absorbent. Secondly, the characteristic absorption peaks of sulfite corresponding to 455 and 1020 cm ^-1 . The bending vibrations of the distorted _SO2 molecules in HEM- _SO2 corresponding to 505, 548 and 646 cm ^-1 indicate that the chemical reaction of the system components causes _SO2 absorption. After 5 absorption-desorption cycles, the absorption peaks of HEM-TEM-40 have changed to a certain extent. The same phenomenon can also be observed in the characterization of the absorbent 1HNMR and 13CNMR nuclear magnetic resonance after 5 absorption-desorption cycles. The δ values of each characteristic peak have changed greatly, as shown in Figure 10 of the specification. This also shows that the absorbent cannot be completely restored to its original state after desorption, and its regeneration performance is not ideal, which affects its absorption capacity for cyclic use to a certain extent. This also explains the slightly insufficient stability of HEM-TEM-40 in the cycle experiment.

FT-IR characterization of the absorbent before and after the reaction, as well as 1HNMR and 13CNMR nuclear magnetic resonance characterization were also performed for other solvent selections. The total sulfur absorption after 5 regeneration cycles of other solvent selections was lower than that of Comparative Example 6, which was omitted due to the length of the specification.

Examples 1 to 3

The same implementation steps as in Example 1 were used to repeat the experiment to verify the standard deviation of sulfur absorption after 5 regeneration cycles. The results are shown in Figure 11 of the specification.

It is obvious that in repeated experiments, the specific implementation scheme using polyethylene glycol dimethyl ether (NHD) as a solvent showed extremely high repeatability, and the sulfur absorption in each regeneration cycle was more uniform and stable than that of other solvents, which fully demonstrates that it has better industrial application prospects.

The following examples respectively investigate the effects of four influencing factors, namely, reaction temperature, solute mass percentage, _SO2 concentration and flue gas water content, on the morpholine-based cyclic amine desulfurizer with high regeneration cycle performance described in the present invention. Taking the first sulfur absorption amount as the evaluation index, a three-level optimization orthogonal experiment of the above four factors was designed.

Example 4

In Example 4, the mass percentage of N-(2-hydroxyethyl)morpholine is 30%, SO ₂ concentration = 5720 mg/m ³ , nitrogen is used as carrier gas, the gas flow rate is 700 ml/min, the reaction temperature is 293.15 K, the water content is 10%, and the SO ₂ absorption capacity is 972.37 mg.

Example 5

In Example 5, the mass percentage of N-(2-hydroxyethyl)morpholine is 20%, SO ₂ concentration = 2860 mg/m ³ , nitrogen is used as carrier gas, the gas flow rate is 700 ml/min, the reaction temperature is 293.15 K, the water content is 20%, and the SO ₂ first absorption capacity is 896.78 mg.

Example 6

In Example 6, the mass percentage of N-(2-hydroxyethyl)morpholine is 40%, SO ₂ concentration = 5720 mg/m ³ , nitrogen is used as carrier gas, the gas flow rate is 700 ml/min, the reaction temperature is 313.15 K, the water content is 20%, and the SO ₂ first absorption capacity is 518.5 mg.

Example 7

In Example 7, the mass percentage of N-(2-hydroxyethyl)morpholine is 30%, SO ₂ concentration = 2860 mg/m ³ , nitrogen is used as carrier gas, the gas flow rate is 700 ml/min, the reaction temperature is 313.15 K, the water content is 0%, and the SO ₂ first absorption capacity is 318.89 mg.

Example 8

In Example 8, the mass percentage of N-(2-hydroxyethyl)morpholine is 20%, SO ₂ concentration = 8580 mg/m ³ , nitrogen is used as carrier gas, the gas flow rate is 700 ml/min, the reaction temperature is 313.15 K, the water content is 10%, and the SO ₂ first absorption capacity is 519.85 mg.

Example 9

In Example 9, the mass percentage of N-(2-hydroxyethyl)morpholine is 40%, SO ₂ concentration = 2860 mg/m ³ , nitrogen is used as carrier gas, the gas flow rate is 700 ml/min, the reaction temperature is 333.15 K, the water content is 10%, and the SO ₂ first absorption capacity is 172.77 mg.

Example 10

In Example 10, the mass percentage of N-(2-hydroxyethyl)morpholine is 30%, SO ₂ concentration = 8580 mg/m ³ , nitrogen is used as carrier gas, the gas flow rate is 700 ml/min, the reaction temperature is 333.15 K, the water content is 20%, and the SO ₂ first absorption capacity is 246.5 mg.

Embodiment 11

In Example 11, the mass percentage of N-(2-hydroxyethyl)morpholine is 30%, SO ₂ concentration = 5720 mg/m ³ , nitrogen is used as carrier gas, the gas flow rate is 700 ml/min, the reaction temperature is 333.15 K, the water content is 0%, and the SO ₂ first absorption capacity is 178.6 mg.

The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims (5)

1. A morpholine cyclic amine desulfurizing agent with high regeneration cycle performance is characterized in that the desulfurizing agent is prepared by mixing N- (2-hydroxyethyl) morpholine serving as a solute and polyethylene glycol dimethyl ether serving as a solvent, wherein the mass percentage of the N- (2-hydroxyethyl) morpholine serving as the solute is 20% -50%.

2. The morpholino cyclic amine desulfurizing agent according to claim 1, characterized in that: the mass percentage of the N- (2-hydroxyethyl) morpholine serving as a solute in the morpholine cyclic amine desulfurizing agent is 30% -40%.

3. The preparation method of the morpholine cyclic amine desulfurizer with high regeneration cycle performance is characterized by mainly comprising the following steps:

(1) Mixing N- (2-hydroxyethyl) morpholine serving as a solute and polyethylene glycol dimethyl ether serving as a solvent, wherein the mass percentage of the N- (2-hydroxyethyl) morpholine serving as the solute is 20% -50% as a mixed solution;

(2) And (3) uniformly dispersing the N- (2-hydroxyethyl) morpholine in the mixed solution obtained in the step (1) at normal temperature or at the temperature of 20-40 ℃ by stirring, so as to obtain the morpholine cyclic amine desulfurizer with high regeneration cycle performance.

4. A method of preparation according to claim 3, characterized in that: the mass percentage of the N- (2-hydroxyethyl) morpholine serving as a solute in the mixed solution is 30% -40%.

5. The use of the morpholine cyclic amine desulfurizing agent with high regeneration cycle performance as claimed in claim 1 in the field of organic amine desulfurization.