A method of disposing of aerogel high boiler byproducts

Abstract

The application discloses a kind of aerogel high-boiling substance by-product disposal method, comprising the following steps: step 1: high-boiling substance is added to the container with nitrogen methyl pyrrolidone;Wherein, the mass of high-boiling substance is M, and the addition amount of nitrogen methyl pyrrolidone is at least 0.5M;Step 2: nitrogen is filled into the container, so that the container is in nitrogen atmosphere;Step 3: the container is heated, so that the temperature of the mixture in the container is kept above at least 70 DEG C, and the high-boiling substance is dissolved by continuous stirring;Step 4: the mixture in the container is discharged into the incinerator for incineration;Step 5: the solid obtained after incineration is disposed as solid waste.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hazardous solid waste treatment, and particularly relates to a disposal method of aerogel high-boiling byproduct. BACKGROUND

[0002] Aerogel is a kind of solid material with a nano-porous three-dimensional network structure, which has a wide range of applications in various technical fields. Silica aerogel belongs to inorganic non-metallic materials, which has extremely high chemical stability, extremely wide temperature resistance range, extremely low thermal conductivity, and is non-combustible, non-toxic, and physiologically inert. It is currently the best thermal insulation material in the fields of aerospace, petrochemical, power, construction, medicine, environmental protection, and new energy.

[0003] Silica aerogel is generally prepared by using silicon ester, water glass, and silica sol as a silicon source, through a sol-gel method to obtain a gel, and then treating the gel with a modifier, and finally drying to obtain. In the prior art, the aerogel has the problems of high energy consumption, long cycle, and difficult treatment of recovered solvents. Especially for the recovery of solvents formed and recovered during the production of aerogel materials, the industry performs rectification treatment. Although the rectified solvents can be reused, a large amount of high-boiling byproducts will be formed after multiple rectifications, and these high-boiling byproducts can only be treated as hazardous solid waste. However, as the production time and output of enterprises increase, the amount of these high-boiling byproducts increases, and because the high-boiling byproducts contain methanol (or ethanol) and ammonia water, the high-boiling byproducts are listed as hazardous solid waste by environmental evaluation, and the corresponding treatment cost is also increasing.

[0004] Patent CN115893430A uses unlimited recycling of ethanol containing impurities generated during aerogel production to reduce production costs; but this method will introduce impurities into the product, and also introduce other impurity ions, which will cause the product quality to decrease after multiple cycles.

[0005] Therefore, the prior art lacks an effective and low-cost treatment method for such high-boiling byproducts. SUMMARY

[0006] In view of the above problems in the prior art, the present application provides a disposal method of aerogel high-boiling byproduct to solve the problem that the prior art lacks an effective treatment method for such high-boiling byproducts.

[0007] To solve the above technical problems, the present application adopts the following technical solutions:

[0008] A disposal method of aerogel high-boiling byproduct, comprising the following steps:

[0009] Step 1: adding nitrogen methyl pyrrolidone (NMP) into the container with high-boiling substance; wherein, the mass of the high-boiling substance is M, and the added amount of the nitrogen methyl pyrrolidone is at least 0.5M;

[0010] Step 2: filling nitrogen into the container to make the inside of the container in a nitrogen atmosphere;

[0011] Step 3: heating the container to keep the temperature of the mixture in the container at least 70℃, and continuously stirring to dissolve the high-boiling substance;

[0012] Step 4: discharging the mixture in the container into an incinerator for incineration;

[0013] Step 5: taking the solid obtained after incineration as solid waste for disposal.

[0014] Preferably, the high-boiling substance is viscous high-boiling substance obtained after rectification treatment of the solvent recovered in the production process of silica aerogel.

[0015] Preferably, in Step 4, the incineration is carried out at least under normal pressure, or can be carried out under pressure. However, the incineration temperature is not limited, and the conventional incineration process can achieve the technical effects of the present application.

[0016] Preferably, in Step 4, oxygen-rich air is introduced into the incinerator during incineration; wherein, the oxygen content of the oxygen-rich air is 30% to 45% according to the volume percentage.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] In the research on the treatment method of high-boiling substance, it is found that the high-boiling substance is very difficult to treat, it is not soluble in most solvents, and even after being dissolved in some organic solvents, it is also difficult to be completely incinerated, because there are still a lot of high-boiling substances that are not completely incinerated after incineration, which also makes the treatment of these high-boiling substances very difficult; the present application unexpectedly found that after the high-boiling substance is dissolved in NMP, methanol and a small amount of ammonia can be completely incinerated in an incinerator without strict temperature control requirements, and the product obtained after incineration can be treated as ordinary solid waste, which greatly reduces the treatment difficulty and cost of high-boiling substance, especially when a large amount of high-boiling substance is treated, the method flow of the present application is simple, the operation difficulty is low, and it is easy to implement, and has good industrial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 DSC test pattern of the product after incineration of Example 1.

[0020] Figure 2 TG test pattern of the product after incineration of Example 1. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the present application belong to the scope of protection of the present application.

[0022] Unless otherwise specified in specific cases, the numerical ranges listed in the present application include the upper limit and lower limit values, and all integers and fractions within the range, and are not limited to the specific values listed in the defined range.

[0023] A method for disposing aerogel high-boiling residue by-products

[0024] The method described in the present application comprises the following steps:

[0025] Step 1: adding N-methyl pyrrolidone (NMP) into a container containing high-boiling residue; wherein the mass of the high-boiling residue is M, and the added amount of N-methyl pyrrolidone is at least 0.5M;

[0026] Step 2: filling nitrogen into the container to make the inside of the container in a nitrogen atmosphere;

[0027] Step 3: heating the container to keep the temperature of the mixture in the container at least 70℃, and continuously stirring to make the high-boiling residue partially dissolved or form a suspension;

[0028] Step 4: discharging the mixture in the container into an incinerator for incineration, which can be preferably normal pressure open incineration;

[0029] Step 5: disposing the solid obtained after incineration as solid waste.

[0030] The present application discloses a kind of treatment method of high-boiling residue, which is used in the production of silica aerogel.The high-boiling residue mainly has aerogel structure, and contains 20-70% methanol (or ethanol) solvent and a little ammonia, and a little methyl group on the branched chain of the high-boiling residue, which is carried by the raw material methyltrimethoxysilane.The viscosity of the high-boiling residue decreases at high temperature, and increases after cooling, and the alcohol content of the high-boiling residue is high, so the high-boiling residue is classified as hazardous waste and needs special treatment according to the requirements of hazardous waste.However, the high-boiling residue obtained by rectification treatment of the solvent recovered in the production of silica aerogel is viscous, and cannot be directly ignited, even if it is ignited after adding a combustion improver such as methanol (or ethanol), it cannot be burned to dryness to obtain a silica product, and even if it is incinerated at high temperature, the product still exists in a viscous state.In order to solve the problem of high-boiling residue blocking the reboiler in the rectification process of the rectification column, the present application unexpectedly found that the high-boiling residue can be effectively dissolved by NMP to form a mixture, and the mixture can be completely converted into ordinary solid waste of light-weight solid silica by open ignition incineration, thereby greatly reducing the treatment difficulty and cost of the high-boiling residue.

[0031] In some embodiments, the temperature is maintained at least at 70℃ during the continuous stirring of the mixture in the container in step 3, of course, the higher the temperature, the more conducive to the dissolution of the high-boiling residue, but the higher the temperature, the higher the energy consumption, if the high-boiling residue is to be fully dissolved, the energy consumption is too high, which will lead to the increase of the overall treatment cost, and even if the dissolution temperature is high when using other solvents for dissolution, the incineration still contains a large amount of alcoholate, which is difficult to convert into ordinary solid waste, therefore, the temperature is preferably controlled within 70-100℃.

[0032] In some embodiments, the incineration temperature of the incinerator in step 4 does not need to be controlled, the incineration can be carried out at least under normal pressure, or can be carried out under pressure, but the incineration temperature is not limited, and the conventional incineration process can achieve the technical effect of the present application.

[0033] In some embodiments, oxygen-enriched air is introduced into the incinerator during the incineration in step 4, wherein the oxygen content of the oxygen-enriched air is 30-45% by volume.The experimental results show that the oxygen-enriched air can promote the speed of combustion, and ordinary air can also incinerate the high-boiling residue.

[0034] II. Examples and comparative examples

[0035] Example 1

[0036] The high-boiling substance generated in the production system of the silica aerogel is collected, and the high-boiling substance with a mass of M is added to a container. According to the mass ratio, the container is added with 0.5M of N-methyl pyrrolidone (NMP). Subsequently, the container is vacuumized while being filled with nitrogen, so that a nitrogen atmosphere is formed in the container. Subsequently, the container is heated so that the temperature of the mixture in the container reaches 70°C, and the heating process is continued with stirring. Next, after the high-boiling substance is mostly dissolved or suspended in the NMP solution, the mixture in the container is discharged into an incinerator for incineration. During the incineration, the incineration temperature is 500°C, and oxygen-rich air is introduced, and the oxygen content in the oxygen-rich air is 30% in terms of the volume percentage. After the incineration until the high-boiling substance is not present in the product, the obtained solid is detected, and the high-boiling substance is not detected. The solid after the incineration can be treated as a general solid waste.

[0037] Example 2

[0038] On the basis of Example 1, the difference is that the amount of NMP added is 1M. The obtained solid is detected, and the high-boiling substance is not detected. The solid after the incineration can be treated as a general solid waste.

[0039] Example 3

[0040] On the basis of Example 1, the difference is that the amount of NMP added is 10M. The obtained solid is detected, and the high-boiling substance is not detected. The solid after the incineration can be treated as a general solid waste.

[0041] Example 4

[0042] On the basis of Example 1, the difference is that the temperature of the mixture in the container is heated to 80°C. The obtained solid is detected, and the high-boiling substance is not detected. The solid after the incineration can be treated as a general solid waste.

[0043] Example 5

[0044] On the basis of Example 1, the difference is that the temperature of the mixture in the container is heated to 100°C. The obtained solid is detected, and the high-boiling substance is not detected. The solid after the incineration can be treated as a general solid waste.

[0045] Comparative Example 1

[0046] Adjustment was made on the basis of Example 1, the difference being that the amount of NMP added was 0.3M. Due to the too small amount of NMP added, after the same incineration time treatment as in Example 1, there was still a large amount of viscous high-boiling substance, and due to the presence of the high-boiling substance, alcohol substances could still be detected inside the high-boiling substance, even after incineration, at this time the high-boiling substance remaining after incineration was still considered to be hazardous solid waste. After continuing to incinerate, although the amount of viscous high-boiling substance was gradually reduced, alcohol compounds were still left in the high-boiling substance, and very long time incineration was needed to completely convert the high-boiling substance into ordinary solid waste.

[0047] Comparative Example 2

[0048] Adjustment was made on the basis of Example 1, the difference being that the temperature of the mixture in the container was heated to 50°C. The heating temperature was too low, and the dissolution effect of the high-boiling substance in the container was not good, which also caused the mixture to have the same problem as in Comparative Example 1 when incineration treatment was performed, and very long time incineration was needed to achieve the treatment effect.

[0049] Comparative Example 3

[0050] Adjustment was made on the basis of Example 1, the difference being that the solvent for dissolving the high-boiling substance was respectively methanol and ethanol. After adding such a combustion-supporting agent as methanol (or ethanol), it could be ignited, but it could not be burned dry into a silicon dioxide product. The mixture of methanol and high-boiling substance, the mixture of ethanol and high-boiling substance were incinerated, and the incineration conditions were exactly the same as in Example 1. After incineration for the same incineration time as in Example 1, there was still a large amount of viscous high-boiling substance in the obtained product, and alcohol could also be detected therein. Further increasing the incineration temperature, adjusting the incineration temperature to 800°C on the basis of Example 1, after incineration, the amount of high-boiling substance in the obtained product was reduced, but part of the alcohol was still left. Further increasing the incineration temperature to 1000°C, long time incineration was needed to completely convert all the high-boiling substance into ordinary solid waste, and the incineration time was much longer than in Example 1.

[0051] Comparative Example 4

[0052] Adjustment was made on the basis of Example 1, the difference being that the high-boiling substance was not dissolved, but was directly placed in the incinerator for incineration, and the incineration temperature was 500°C. After the same incineration time as in Example 1, a large amount of viscous high-boiling substance could be observed in the obtained solid, and alcohol could be detected therein. If the incineration temperature was increased as in Comparative Example 3, the proportion of high-boiling substance in the product was obviously much higher than in Example 1, and even higher than in Comparative Example 3, and alcohol could still be detected in the high-boiling substance remaining after incineration.

[0053] Comparative Example 5

[0054] The experiment was modified from Example 1, with the difference being that the solvents for dissolving the high-boiling-point substances were N,N-dimethylacrylamide (DMF) and N-ethylpyrrolidone (NEP). After heating and dissolving the high-boiling-point substances using these two solvents, the product was then incinerated. After incineration for the same time as in Example 1, some high-boiling-point substances still remained in the product, but the amount was significantly lower than in Comparative Examples 1-4. Upon continued incineration, no viscous high-boiling-point substances were observed in the product. Further testing revealed no high-boiling-point substances. Therefore, while these two solvents can achieve the same effect as in the examples, a longer incineration time is still required to achieve the desired final result.

[0055] III. Results Analysis

[0056] The products after incineration in all embodiments were verified by drying loss, DSC, and TG tests. Since the alcohols, which are present in high concentrations and are relatively dangerous in high-boiling-point substances, have been completely incinerated, they can be disposed of as ordinary solid waste.

[0057] 1. Taking Example 1 and Example 2 as examples, 2.0000g of the calcined powder was weighed and dried in an oven at 150℃ until constant weight was achieved. The loss on drying was calculated, and the results are shown in Table 1.

[0058] Table 1

[0059]

[0060] 2. The product after incineration in Example 1 was used as a sample for DSC testing. The specific testing conditions were as follows: temperature increased from room temperature to 600℃. The specific chromatogram is shown in the figure. Figure 1 As shown. Methanol (or ethanol) has a boiling point of 64.8℃ (78.3℃), which can be obtained from... Figure 1 The absence of peaks below 100℃ indicates that the methanol (or ethanol) in the high-boiling-point substance has completely evaporated. The endothermic peak appearing at 400-600℃ is presumably due to a structural change in the silicide containing methyl groups.

[0061] 3. The product from the incineration of Example 1 was used as a sample for TG testing. The specific testing conditions involved heating from room temperature to 600°C. The specific chromatogram is shown below. Figure 2 As shown. TG testing revealed material loss in the sample at 450℃ in air, which, combined with DSC analysis, is presumably due to the removal of methyl groups from the silicon-oxygen polymer. The thermogravimetric loss was approximately 1%.

[0062] Finally, it needs to be explained that the above examples are only used to illustrate the technical solutions of the present application but not to limit the technical solutions, and those of ordinary skill in the art should understand that the technical solutions of the present application are modified or equivalently replaced without departing from the purpose and scope of the technical solutions, which should be covered in the scope of claims of the present application.

Claims

1. A method of disposing of aerogel high boiler byproducts, comprising, The method comprises the following steps: Step 1: adding N-methyl pyrrolidone into a container containing high-boiling substances; wherein the mass of the high-boiling substances is M, and the amount of the N-methyl pyrrolidone added is at least 0.5M; Step 2: filling the container with nitrogen to make the interior of the container in a nitrogen atmosphere; Step 3: heating the container to keep the temperature of the mixture in the container above at least 70℃, and continuously stirring until the high-boiling substances are partially dissolved or form a suspension; Step 4: discharging the mixture in the container into an incinerator for incineration; Step 5: disposing the solid obtained after incineration as solid waste.

2. The method of claim 1, wherein the aerogel high boiler byproduct is disposed of by, The high-boiling substances are viscous high-boiling substances obtained after rectification treatment of solvents used in the production of silica aerogels.

3. The method of claim 1, wherein the aerogel high boiler byproduct is disposed of by, In step 4, the incineration is carried out at least at normal pressure.

4. The method of claim 1, wherein the aerogel high boiler byproduct is disposed of by, In step 4, oxygen-rich air is introduced into the incinerator during the incineration; wherein the oxygen content in the oxygen-rich air is 30% to 45% according to the volume percentage.

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