A TG-FTIR evaluation method for pyrolysis solid products

Abstract

This invention provides a TG-FTIR evaluation method for pyrolysis solid products, belonging to the technical field of pyrolysis solid product evaluation. The evaluation method provided by this invention uses TG-FTIR coupled with pyrolysis to detect pyrolysis carbon black. It characterizes the carbon black, volatile matter, and ash content, as well as the degree of pyrolysis, quality, and oxidation degree of the pyrolysis carbon black, by using the TG values ​​of each pyrolysis stage and the methane trajectory peak integral. This invention provides a single rating to evaluate the above indicators, thus serving as an effective quality evaluation method for pyrolysis carbon black.

Description

Technical Field

[0001] This invention belongs to the field of evaluation technology of pyrolysis solid products, and particularly relates to a TG-FTIR evaluation method for pyrolysis solid products. Background Technology

[0002] Compared with commercial carbon black, pyrolysis carbon black (CBp) has a complex composition, high impurity content, large particle size and uneven distribution. In particular, the surface covered with incompletely pyrolyzed organic molecules and the oxidation during the pyrolysis process make the surface physicochemical properties of CBp very different from those of carbon black. It is difficult to establish a direct and close relationship between the various indicators analyzed using conventional carbon black analysis methods and its reinforcing performance.

[0003] Therefore, based on conventional physical property analysis, it is very necessary to establish a quality evaluation method suitable for CBp, taking into account its structural characteristics, so that it can establish a closer relationship with the reinforcement performance of CBp, and serve as a supplement to the quality evaluation of CBp. Summary of the Invention

[0004] The purpose of this invention is to provide a TG-FTIR evaluation method that can effectively evaluate pyrolysis carbon black.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a TG-FTIR evaluation method for pyrolysis solid-phase products, the method comprising the following steps:

[0007] 1) The pyrolysis solid phase was detected using TG-FTIR, and the TG-FTIR test conditions were as follows:

[0008] The TG test was conducted under a nitrogen atmosphere, with a temperature range of 30-900℃, a heating rate of 20℃ / min, and a sample purge gas flow rate of 20ml / min.

[0009] FTIR synchronous acquisition of pyrolysis gas spectra was performed using an MCT detector, with each spectrum scanned 8 times to achieve a resolution of 4 cm⁻¹. -1 .

[0010] After the combined test, the TG furnace body was cooled from 900℃ to 400℃, the sample purge gas was switched to air atmosphere, and after holding the temperature for 2 minutes, it was heated to 900℃ at a rate of 20℃ / min, and the test ended.

[0011] 2) Analysis of TG-FTIR results

[0012] Select 3016cm -1 2935cm -1 2360cm -1and 2178cm -1 The characteristic peaks of methane, hydrocarbons, carbon dioxide and carbon monoxide were used as the characteristic peaks, and the trajectory diagrams of the characteristic peaks of each component were extracted.

[0013] The TG-FTIR results were analyzed, and the TG values ​​(%) for the following segments were calculated: 30-350℃ N2 FTIR segment; 350-550℃ N2 FTIR segment; 550-900℃ N2 FTIR segment; 400-900℃ Air segment; and Residual Air segment.

[0014] The methane trajectory peak integrals for the characteristic methane peak in the 450-800℃ range were calculated, 10 -2 / mg;

[0015] 3) The properties of the pyrolyzed solid phase were characterized based on the obtained analytical results.

[0016] The TG value / % in the FTIR section of N2 at 30-350℃ characterizes the volatile matter in the pyrolysis solid phase; the smaller the TG value / %, the smaller the volatile matter in the pyrolysis solid phase.

[0017] The TG value / % in the FTIR section of N2 at 350-550℃ characterizes the residual rubber hydrocarbons in the cracked solids. The smaller the TG value / %, the smaller the residual rubber hydrocarbons in the cracked solids, indicating a greater degree of cracking of the cracked solids.

[0018] The TG value / % in the FTIR range of 50-900℃ N2 represents the decomposable and removable groups of the pyrolysis solid. The smaller the TG value / %, the fewer decomposable and removable groups the pyrolysis solid has, indicating that the oxidation of the pyrolysis solid is less complete.

[0019] The TG value / % in the 400-900℃ Air section characterizes the carbon black content of the pyrolysis solids; the higher the TG value / %, the higher the carbon black content of the pyrolysis solids.

[0020] The TG value / % of the Residual Air section characterizes the ash content of the pyrolysis solids. The smaller the TG value / % is, the smaller the ash content of the pyrolysis solids.

[0021] The methane trajectory peak integral in the range of 450-800℃ characterizes the degree of cracking of the solid phase, and the smaller the peak area, the better the cracking of the solid phase.

[0022] Preferably, the pyrolysis solid is pyrolysis carbon black.

[0023] Preferably, the standard for the TG value / % of the 30-350℃ N2 FTIR section of qualified pyrolysis carbon black is ≤2.

[0024] Preferably, the standard for the TG value / % of the 350-550℃ N2 FTIR section of qualified pyrolysis carbon black is ≤1.5.

[0025] Preferably, the standard for the TG value / % of the 50-900℃ N2 FTIR section of qualified pyrolysis carbon black is ≤4.

[0026] Preferably, the standard for the TG value / % of qualified pyrolysis carbon black in the 400-900℃ Air section is ≥75.

[0027] Preferably, the standard for the TG value / % of the Residual Air segment of qualified pyrolysis carbon black is ≤18.

[0028] Preferably, the standard for the alkane trajectory peak integral of qualified pyrolysis carbon black is ≤4.

[0029] The beneficial effects of this invention are as follows: The TG-FTIR evaluation method established by this invention can not only evaluate the carbon black, volatile matter and ash content in one step, but also evaluate the degree of cracking, quality and oxidation. Therefore, it can be used as an effective quality evaluation method for CBp. Attached Figure Description

[0030] Figure 1 TG curves for each batch of qualified CBP products from Shuangxing's online production line;

[0031] Figure 2 The FTIR spectra of the CBp product were extracted at various temperature points during the TG test.

[0032] Figure 3 The trajectory diagrams for methane, hydrocarbons, carbon dioxide, and carbon monoxide;

[0033] (a) is the trajectory diagram of methane, (b) is the trajectory diagram of hydrocarbons, (c) is the trajectory diagram of titanium dioxide, and (d) is the trajectory diagram of carbon monoxide. Detailed Implementation

[0034] Example 1

[0035] TG-FTIR test of pyrolysis carbon black

[0036] This invention selects qualified CBP products from various batches of Shuangxing's online production line for TG-FTIR testing. The testing conditions are as follows:

[0037] The TG test was conducted under a nitrogen atmosphere, with a temperature range of 30-900℃, a heating rate of 20℃ / min, and a sample purge gas flow rate of 20ml / min.

[0038] FTIR synchronous acquisition of pyrolysis gas spectra was performed using an MCT detector, with each spectrum scanned 8 times to achieve a resolution of 4 cm⁻¹. -1 .

[0039] To obtain both carbon black and ash content simultaneously, after the combined test, the TG furnace was first cooled from 900℃ to 400℃, the sample purge gas was switched to air, and after holding the temperature for 2 minutes, it was raised to 900℃ at a rate of 20℃ / min, and the test ended.

[0040] Example 2

[0041] TG-FTIR Result Analysis

[0042] from Figure 1 The TG curves of the CBP products show that there are still significant differences between different batches of CBP.

[0043] from Figure 2 The FTIR spectra extracted from the CBp product at various temperature points during the TG test show that the gaseous products released during the entire process mainly include water, hydrocarbons, methane, carbon monoxide, and carbon dioxide.

[0044] To more intuitively illustrate the temperature range of each major release product, a temperature of 3016 cm⁻¹ was selected. -1 2935cm -1 2360cm -1 and 2178cm -1 Characteristic peaks for methane, hydrocarbons, carbon dioxide, and carbon monoxide were used as the base peaks, respectively. Trajectory diagrams of the characteristic peaks for each component were extracted, and the results are as follows: Figure 3 As shown in (a)-(d).

[0045] from Figure 3 (a) It can be seen that methane release mainly occurs in the range of 450-800℃, with methane being released from the cracking of the remaining rubber chains to the removal of short chains grafted onto the CBp surface. Figure 3 (b) The release range of hydrocarbon products can be divided into three segments: before 350°C, it is low molecular weight oil; from 350-550°C, it is the cracking of residual rubber chains; and from 550-800°C, it is the removal of surface-grafted short chains. Figure 3 (c) and Figure 3 The release of carbon monoxide and carbon dioxide in (d) is mainly concentrated after 550℃, which comes from the decomposition of calcium carbonate and the removal of oxygen-containing groups on the surface of CBp. Judging from the changes in the peak intensity and weight loss of carbon monoxide and carbon dioxide in this temperature range, the pyrolysis products after 550℃ contain a small amount of short chains grafted on the surface of CBp, and most of the products are carbon monoxide and carbon dioxide.

[0046] Subsequently, based on the results of coupled FTIR analysis, the pyrolysis process of CBp can be divided into three parts:

[0047] (1) The temperature range of 30℃-350℃ is mainly water and low molecular weight oil. This part is the volatile content of CBp.

[0048] (2) 350℃-550℃ mainly corresponds to the further decomposition of residual rubber hydrocarbons in CBp. The content in this range reflects the quality of the cracking.

[0049] (3) 550℃-900℃ is mainly due to the grafted short chains and oxygen-containing functional groups with higher thermal stability on the CBp surface. This region is mainly due to the decomposition of oxygen-containing functional groups, so it also reflects the degree of oxidation of the CBp surface.

[0050] The weight loss, carbon black content, and ash content corresponding to each pyrolysis stage are shown in Table 1.

[0051] Table 1. Weight loss, carbon black and ash content corresponding to each pyrolysis stage of CBp

[0052]

[0053] As shown in Table 1, the volatile matter content of each CBp ranges from 1% to 2%, with the residual rubber hydrocarbon content of all except CBp-5 being less than 1%, ash content around 17%, and carbon black content all above 75%. Comparatively, CBp-5 shows insufficient pyrolysis, CBp-3 exhibits the highest degree of oxidation, while CBp-6 shows the lowest.

[0054] Given that the weight loss between 350-550℃ may include some calcium carbonate decomposition (such as calcium carbonate in CBp-3 being earlier than in other samples), it is difficult to accurately characterize the degree of cracking. Therefore, the peak areas of the hydrocarbon and methane trajectory diagrams were further integrated, and the size of the peak area per unit mass was used to characterize the degree of cracking, as shown in Table 2.

[0055] The data in the table show that CBp-5 has the highest release of methane and other hydrocarbons, while CBp-3 has the lowest release of both. The release of methane and other hydrocarbons in all samples shows a high degree of consistency. Therefore, the integral size of the methane release trajectory per unit mass of CBp can be used to characterize the degree of CBp cracking.

[0056] Based on the TG-FTIR analysis results of different CBp samples, the index values ​​that this test method should achieve to evaluate CBp are shown in Table 3:

[0057] Table 3 Reference Values ​​for TG-FTIR Evaluation Indicators of CBp

[0058]

[0059] In summary, given the unique characteristics of CBp, in addition to the conventional carbon black evaluation system indicators, it is also very necessary to evaluate its degree of pyrolysis and surface oxidation. The quality of CBp pyrolysis and the degree of surface oxidation are closely related to its reinforcing performance. The more complete the pyrolysis and the less the surface oxidation, the closer its physicochemical properties are to commercial carbon black, and the more beneficial it is to improving the reinforcing performance.

Claims

1. A TG-FTIR evaluation method for pyrolysis carbon black, characterized in that, The method includes the following steps: 1) The pyrolysis carbon black was tested using TG-FTIR, and the TG-FTIR test conditions were as follows: The TG test was conducted under a nitrogen atmosphere, with a temperature range of 30-900℃, a heating rate of 20℃ / min, and a sample purge gas flow rate of 20ml / min. FTIR synchronous acquisition of pyrolysis gas spectra was performed using an MCT detector, with each spectrum scanned 8 times to achieve a resolution of 4 cm⁻¹. -1 ; After the combined test, the TG furnace body was cooled from 900℃ to 400℃, the sample purge gas was switched to air atmosphere, and after holding the temperature for 2 minutes, it was heated to 900℃ at a rate of 20℃ / min, and the test ended. 2) Analysis of TG-FTIR results Select 3016 cm -1 2935 cm -1 2360 cm -1 and 2178 cm -1 The characteristic peaks of methane, hydrocarbons, carbon dioxide, and carbon monoxide were used as the characteristic peaks, and the trajectory diagrams of the characteristic peaks of each component were extracted. Analysis of the TG-FTIR results yielded the TG values ​​(%) for the following segments: 30-350℃ N2, 350-550℃ N2, 550-900℃ N2, 400-900℃ Air, and Residual Air. The methane trajectory peak integrals for the characteristic methane peak in the 450-800℃ range were calculated, 10 -2 / mg; 3) The properties of the pyrolysis carbon black were characterized based on the obtained analytical results. The TG value / % in the FTIR section of N2 at 30-350℃ characterizes the volatile matter of pyrolysis carbon black; the smaller the TG value / %, the smaller the volatile matter of pyrolysis carbon black. The TG value / % in the FTIR section of N2 at 350-550℃ characterizes the residual rubber hydrocarbons in pyrolysis carbon black. The smaller the TG value / %, the smaller the residual rubber hydrocarbons in the pyrolysis carbon black, indicating a greater degree of pyrolysis. The TG value / % in the FTIR range of 50-900℃ N2 represents the decomposable and removable groups of pyrolysis carbon black. The smaller the TG value / %, the fewer the decomposable and removable groups of pyrolysis carbon black, indicating a lower degree of oxidation of pyrolysis carbon black. The TG value / % in the 400-900℃ Air section characterizes the carbon black content of pyrolysis carbon black. The higher the TG value / %, the higher the carbon black content of pyrolysis carbon black. The TG value / % of the Residual Air section characterizes the ash content of the pyrolysis carbon black. The smaller the TG value / %, the smaller the ash content of the pyrolysis carbon black. The methane trajectory peak integral in the range of 450-800℃ characterizes the degree of cracking of pyrolysis carbon black, and the smaller the peak area, the better the cracking of pyrolysis carbon black.

2. The evaluation method according to claim 1, characterized in that, The standard for qualified pyrolysis carbon black at 30-350℃ N2, FTIR segment TG value / % is ≤2.

3. The evaluation method according to claim 2, characterized in that, The standard for qualified pyrolysis carbon black at 350-550℃ N2, FTIR segment TG value / % is ≤1.

5.

4. The evaluation method according to claim 3, characterized in that, The standard for qualified pyrolysis carbon black at 50-900℃ N2, FTIR segment TG value / % is ≤4.

5. The evaluation method according to claim 4, characterized in that, The standard for qualified pyrolysis carbon black in the 400-900℃ Air section is ≥75 TG value / % 6. The evaluation method according to claim 5, characterized in that, The standard for the TG value / % of the Residual Air section of qualified pyrolysis carbon black is ≤18.

7. The evaluation method according to claim 6, characterized in that, The standard for the methane trajectory peak integral of qualified pyrolysis carbon black is ≤4.

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