CN114428123A

CN114428123A - Analysis and detection method for laser pyrolysis of solid-liquid organic matter

Info

Publication number: CN114428123A
Application number: CN202011090623.4A
Authority: CN
Inventors: 王龙元
Original assignee: Beijing Fengtest Biotechnology Co ltd
Current assignee: Beijing Fengtest Biotechnology Co ltd
Priority date: 2020-10-15
Filing date: 2020-10-15
Publication date: 2022-05-03

Abstract

The invention provides a method for pyrolyzing a carbonaceous material by taking laser as a heat source and carrying out rapid quantitative analysis on a pyrolysis product, so as to meet the analysis and detection requirements of high-temperature rapid pyrolysis of the carbonaceous material, reasonably represent the pyrolysis property of the carbonaceous material under a high-temperature condition and meet the industrial application and analysis requirements of the carbonaceous material under certain extreme conditions. The method integrates a reaction part and a detection part including a laser and a reactor to improve detection efficiency, sensitivity and accuracy. The reactor has high-temperature air tightness, can measure the temperature in the reactor, can also measure the accurate quality of a sample and residues after reaction, and is convenient for collecting the residues for other analysis. The pyrolysis product can directly enter the detection part for detection, and the detection part can accurately detect the pyrolysis gas-phase product. The detection and analysis method has the advantages of high speed, small sample amount, high precision, high sensitivity and the like, can simulate different pyrolysis conditions of the carbonaceous material, quantitatively analyze the pyrolysis property under the conditions, and provide analysis and detection basis for the pyrolysis process under extreme conditions such as plasma cracking.

Description

Analysis and detection method for laser pyrolysis of solid-liquid organic matter

Technical Field

The invention relates to a laser thermal cracking technology, in particular to a method for thermally cracking solid liquid organic matters at high temperature and analyzing and detecting products of all phases.

Background

The pyrolysis reaction refers to a series of decomposition reactions of a substance in a heated state, physical properties and chemical properties of reactants can be researched by utilizing the pyrolysis reaction, the state of the reactants in the reaction process can be distinguished, and the thermal cracking of solid liquid organic matters is an effective means for researching composition and physicochemical properties of the solid liquid organic matters and analyzing thermal cracking products of the solid liquid organic matters.

The composition of the pyrolysis product depends on the physical property and the chemical property of the solid liquid organic matter, and the reaction conditions of temperature, temperature rising rate, gas atmosphere and the like. The mechanism of thermal cracking of most solid liquids is very complex, involving a series of reactions in series and in parallel. At present, a common method for researching the pyrolysis characteristics of solid and liquid organic matters is to use a thermogravimetric analyzer to perform thermogravimetric analysis (TG or TGA), Differential Thermal Analysis (DTA) and scanning calorimetry (DSC) to show the thermal stability/thermal effect variation of a substance in a certain temperature range, or to analyze the composition of pyrolysis products by combining with chromatographic mass spectrometry. Laboratories also often use small pyrolysis devices such as electric furnaces in which a reactor or reaction tube is placed and the sample is heated to a predetermined pyrolysis temperature by using high temperature radiation in the furnace to supply energy to the reactor. The defects of the mode are that the detection period is long, the heating rate is slow, the temperature of the reactor is inconsistent with the temperature of the inner wall of the furnace, the requirement on the pyrolysis of single sample particles is particularly not met, and the gas products generated by the pyrolysis are difficult to accurately and timely analyze.

For the pyrolysis process with high reaction temperature and fast temperature rise rate, the conventional analysis means can not simulate the actual pyrolysis process, such as the preparation of acetylene by cracking carbonaceous materials with plasma, the reaction temperature is above 1000 ℃, and the temperature rise rate is 10⁴The reaction is carried out in a reducing atmosphere at a temperature of more than DEG C/s for millisecond reaction, and belongs to the reaction process under extreme conditions. The biomass is subjected to flash pyrolysis under the conditions of air isolation, normal pressure and rapid heating to 400-600 ℃, and the heating rate is about 10⁴K/s, the reaction time is less than 2s, and the chain molecular bond is rapidly broken under the condition, so that the coking and gas production are reduced to the minimum, and the biomass oil is obtained to the maximum.

Compared with a heating wire, the laser has the characteristics of energy concentration and small energy dissipation, the pyrolysis temperature and the heating rate can be greatly improved, and people have partially tried to apply the laser in pyrolysis analysis. For example, CN201735397 discloses a laser pyrolysis method, which comprises a purging device, a reaction device and a cooling device, wherein the reaction device comprises a reactor and a laser, and the claimed temperature rise rate of a sample can be up to 10⁵Rapid heating at a temperature of DEG C/s. The reactor is a glass box body, the top surface of the reactor is made of far infrared glass and is over against laser emitted by the laser, the bottom surface and the periphery of the glass box body are made of quartz glass, the volume of the reactor is small, the retention time of a product in the reactor is shortened, and secondary reaction in the reactor is avoided. The sample can be continuously fed or the single sample particle can be pyrolyzed.

The above patent fails to accurately and quantitatively analyze the sample and the product, so that the practicability of the method is greatly reduced; the system is lack of a temperature measuring device, and the laser heating is judged to be difficult to reach the heating rate according to the actual detection and temperature measurement, and the actual heating rate is measured to be about 10⁴At 10 ℃ per second⁵The conclusion of the temperature rise rate of DEG C/s lacks theoretical and practical support; the transmittance of common far infrared glass to carbon dioxide laser with the wavelength of 10.6 mu m is not a hundred percent, so the glass can be melted under the irradiation of laser with high energy density, and carbon deposition is inevitably and rapidly generated on the surface of the far infrared glass above the device to shield a light path to cause the damage and cracking termination of the device due to narrow reaction space; the melting point of the quartz glass used as a reactor material is too low, and part of laser is irradiated to the bottom of the device to cause ablation of the reactor; there is no indication of how the pyrolyzed product may be further detected and utilized. For the analysis and detection of the acetylene preparation process by the carbonaceous material cracking by the plasma, the problems need to be solved.

CN208395061 discloses a device suitable for laser pyrolysis, which uses laser as a heat source to scan an organic high molecular polymer precursor, and realizes ceramic transformation through pyrolysis reaction. Laser cracking device belongs to apparatus for producing in this patent, puts emphasis on prior art problems such as inert gas protection effect is not good enough, can not accurate control laser and base member working distance, can not real-time weighing calculation productivity. The method is difficult to detect the gas product and the generated cracked gas product still causes pollution to the environment; the important data of real-time temperature cannot be measured.

CNIO4198381 and CN204086108 disclose an oil shale pyrolytic reaction tracker, the instrument includes a pyrolysis device, a laser emitter and a signal receiving device, through placing the oil shale sample in the pyrolysis device, the electric signal generated by the oil shale sample in the pyrolysis environment under the laser irradiation is measured, and the analysis of the pyrolysis characteristic based on the photovoltaic effect can be realized. By applying the photovoltaic effect to the analysis of the pyrolysis characteristics, the technical effect of reducing the complexity of research and analysis is achieved. On the basis, CN205352941 further provides a laser ultrasonic technology-based oil shale real-time pyrolysis detection method, and by utilizing the advantages of non-contact, high precision, no damage, low requirement on the spatial position of a detection part, remote measurement, rapid omnibearing scanning, wide frequency band, high spatial resolution, special directionality and the like of the laser ultrasonic technology, the physical and chemical changes of an oil shale sample are detected in real time, and the pyrolysis characteristics of the oil shale sample are obtained through analysis. In the three patents, laser is used as a detection means instead of a main heat source, and under the condition that the sample is not directly measured, the influence of the laser on the temperature of the sample cannot be measured, and the key data of the actual temperature of the sample is lost.

CNIO5044079 discloses a method and a device for cracking organic matters, wherein the cracking is carried out by using laser in a scanning electron microscope, the cracking process of the organic matters is observed in situ based on the scanning electron microscope and a focusing laser, the in-situ analysis of the structure and the form of the organic matters changing along with time in the cracking process is realized, and the method and the device can be used for distinguishing different types of organic matters, evaluating the crude oil capability of different organic matters and the like. The patent uses a scanning electron microscope as a detection means to observe the structural morphology of the organic matter, but the detection means is lacked for the chemical composition change of each phase product.

The methods are beneficial to a great deal of exploration on laser thermal cracking, the technology still faces the problems that a gas product is difficult to accurately measure quantitatively, the actual temperature of a detected sample is difficult to accurately measure in real time, the device is high temperature and high pressure resistant, the sealing capability is insufficient, the operation is complicated and the like, how to properly solve the problems is a problem which is urgently needed to be solved in practical application in realizing efficient, accurate and comprehensive laser thermal cracking measurement.

Disclosure of Invention

On the basis of the analysis, through a plurality of trials and experiments, the invention provides a laser pyrolysis analysis and detection method, and a detection chamber is used for detecting the heightThe high-temperature and high-pressure tolerance is strong, and the maximum temperature of 3000 ℃, the maximum pressure of more than 400kPa and 10 can be realized⁴Analyzing and detecting the thermal cracking process under the extreme condition of temperature rise rate above DEG C/s; the detected object is measured in real time by using a bicolor infrared thermometer, the temperature range can reach 3000 ℃ at most, the response time only needs 10ms, and the error is within 1 ℃; the cracking device, the gas chromatography and the mass spectrum are designed integrally, so that the chemical composition of the thermal cracking gas phase product can be analyzed quantitatively immediately after cracking, and the solid product can be collected for quantitative analysis. The problems in the application of the laser thermal cracking technology are solved well.

The invention is realized by adopting the following technical route, and the flow schematic diagram is shown in figure 1.

1. A laser thermal cracking analysis and detection system comprises the following steps

S1: preparation and placement of the sample. Drying a non-volatile sample in an oven at 105 ℃ for 2h, placing the sample in the center of a sample disc, measuring the accurate mass of the sample by adopting a high-precision electronic balance with the precision of 0.01mg, placing the sample disc in the center of a laser thermal cracking reactor, closing and sealing the laser thermal cracking reactor, and correcting a bicolor infrared thermometer.

S2: setting the thermal cracking conditions. The laser pyrolysis reaction time is set on a timer, and the laser irradiation mode and the irradiation power are set on a carbon dioxide laser controller.

S3: and (4) constructing a thermal cracking atmosphere. Preparing the required reaction atmosphere, continuously introducing gas into the reactor for a period of time long enough to completely replace the air in the reactor, wherein the purging speed is determined by the gas composition.

S4: and (3) carrying out laser thermal cracking. Starting recording software of a bicolor infrared thermometer, starting a carbon dioxide laser and starting laser pyrolysis.

S5: and (4) analyzing and detecting the solid gas product. And starting a gas chromatography analysis and detection program immediately after cracking, opening the reactor after the temperature of the reactor is reduced to room temperature, taking out the sample disc and the thermal cracking solid product in the sample disc, measuring the accurate mass by a high-precision electronic balance, and calculating the mass of the solid product.

2. The method is characterized by comprising a carbon dioxide laser heating system, a two-color infrared temperature measuring system, a specially designed reactor, a gas product analysis system and a gas supply system.

3. The method according to any one of the preceding claims, wherein the carbon dioxide laser power is between 1W and 200W, the laser mode comprises single spot irradiation, pulsed irradiation and continuous irradiation, and the laser power error is required to be within ± 5%. The timer is connected with and controls the irradiation and termination of the carbon dioxide laser, and the timing precision requirement reaches 0.1 s.

4. The method according to any of the preceding claims, characterized in that the sample plate is a material which is resistant to high temperatures, does not chemically react with the sample under high temperature conditions and conducts heat quickly, such as stainless steel, tungsten, etc. The sample plate was a bottomed hollow cylinder having an inner diameter of 4mm, an outer diameter of 6mm, a bottom thickness of 1mm and a total height of 3 mm.

5. The method according to any one of the preceding claims, characterized in that the sample injection mass ranges from 0.1mg to 10mg, and the sample pretreatment and injection method comprises the following steps:

(1) crushing a solid sample and pressing the crushed solid sample into a sheet with the diameter of about 3 mm;

(2) dropping a high-viscosity liquid sample at normal temperature in the center of the sample disc;

(3) the low viscosity liquid sample drops directly into the sample tray at normal temperature.

6. A method according to any one of the preceding claims, characterized in that the reactor is made of a stainless steel chamber with an internal diameter of 10mm, the sides of which are provided with two opposite gas channels as gas inlets and outlets, the specifications of the gas channels being adapted to the rest of the apparatus. The height of the inner part of the reaction chamber is 5mm to 10mm, so that the blowing dead zone in the subsequent gas product detection process is reduced, the calculation precision of the yield is improved, the sample to be detected is prevented from being too close to the lens, and the influence of the sample thermal cracking process on the lens is avoided.

7. The method is characterized in that a lens with high transmittance in a wavelength range of infrared temperature measurement and carbon dioxide laser with the thickness of 3mm such as zinc selenide and the like is arranged at the top of the reactor and used for transmitting laser and infrared temperature measurement, an antireflection film is plated on the surface of the lens, and the actual measured transmittance is more than 90%.

8. A method according to any of the preceding claims, characterized in that the reactor connection, near the lens, is sealed with a silicone O-ring and the rest is sealed with a stainless steel ferrule, enabling the whole reactor to be sealed at a pressure of 400 kPa.

9. The method according to any one of the preceding claims, characterized in that the infrared thermometer is calibrated before the experiment to accurately measure the temperature of the sample, and the infrared light radiated by the sample can accurately enter the probe of the two-color infrared thermometer. If the infrared thermometer is affected by the lens at the top of the reactor, the influence of the lens is counteracted by adjusting the built-in parameters of the infrared thermometer through the standard temperature.

10. The method according to any one of the preceding methods is characterized in that the temperature measurement frequency of the infrared thermometer is higher than 10/s, the signal delay is less than 10s, the temperature measurement range is 1000 ℃ to 3000 ℃, the temperature measurement error is less than 3%, and a matched electronic device records the temperature curve in the whole cracking process.

11. A method according to any of the preceding claims, characterized in that the reactor is purged with a purge gas to create a target atmosphere before cracking,

(1) reducing gases such as hydrogen, methane, ethane, acetylene, ethylene, ammonia, etc

(2) Oxidizing gas such as air, oxygen, water vapor, etc

(3) Inert gases such as nitrogen, argon, helium, etc

(4) The mixed gas composed of any of the above gases is a gas which reacts violently after laser irradiation, except for a gas which may explode.

12. The method according to any one of the preceding claims, characterized in that the reactor is purged with gas, the purge gas velocity is controlled to be lower than 100mL/min, the sample is prevented from being blown away, and the initial gas pressure in the laser thermal cracking process is changed.

13. The method according to any one of the preceding claims, characterized in that the reactor is directly connected to a detection device such as a gas chromatograph, a mass spectrometer or the like, and is controlled by a set of valve piping system and a corresponding program, and the sample introduction and detection of the detection device are automatically performed after the program is started.

14. The method according to any one of the preceding claims, characterized in that the working gas required by the detection system is provided by a gas supply part in the system, for gas chromatography, a hydrogen flame ionization detector is usually matched to accurately analyze the concentration of the small molecular hydrocarbons such as methane, ethylene, acetylene, ethane and the like in the cracked gas, and a thermal conductivity detector is combined to analyze the concentration of gases such as hydrogen, carbon monoxide, carbon dioxide and the like, and the working gas is required to be compressed air, carrier gas and hydrogen.

15. The method according to any one of the preceding claims, characterized in that the effective volume of the reactor is calculated by a geometric method or an internal standard method to obtain an accurate value for quantitatively calculating the product yield, wherein the internal standard method requires calculation of an internal standard concentration peak area curve by gas chromatography and then calculation by an interpolation method.

16. A method according to any of the preceding claims, characterized in that suitable filtering or cooling means are provided in the intermediate or one part of the reactor and the detection part to prevent solid particles and low boiling point substances from entering the detection system, to protect the delicate instruments in the detection system and to accurately calculate mass changes.

17. A method according to any of the preceding claims, characterized in that the detection system comprises a gas chromatograph, and the carrier gas used is argon if it is desired to analyze hydrogen, and argon, hydrogen and helium if it is not desired to analyze hydrogen.

18. The method according to any one of the preceding claims, characterized in that the gas circuit is closed during the thermal cracking process of the reactor, thereby avoiding the escape of the laser thermal cracking products and the gas in the thermal cracking atmosphere, which affects the detection accuracy.

19. A method according to any of the preceding claims, characterized in that the carbon dioxide laser is focused by a lens according to the energy density required for thermal cracking, and the relative position of the lens and the sample is calculated to avoid that the energy density is too high to ablate the sample plate and the reactor.

The technical scheme of the invention has the following advantages

1. The invention provides a laser thermal cracking analysis and detection method, which is characterized in that a sample is heated by using a high-energy-density heat source of carbon dioxide laser to realize thermal cracking, so that the highest temperature can reachOver 3000 deg.c and heating rate up to 10⁴The temperature rise rate and the maximum temperature are far higher than those of the existing thermal cracking analysis and detection method, and experiments prove that the method is feasible and can meet the research requirements and production detection requirements of thermal cracking under extreme conditions.

2. The invention provides a laser thermal cracking analysis and detection method, wherein the existing laser thermal cracking analysis methods are qualitative analysis, the thermal cracking process of solid and liquid organic matters can be accurately and quantitatively analyzed by designing an airtight reactor at high temperature and high pressure and connecting a gas chromatograph, the quality of each phase product in the thermal cracking process is obtained, the conversion rate corresponding to the pyrolysis products in the fields of coal chemical industry, petrochemical industry and the like can be effectively estimated, and the application range is greatly increased.

3. The invention provides a laser thermal cracking analysis and detection method, which has the advantages that compared with other thermal cracking analysis methods, the sample consumption is small, the heat transfer effect is weakened, the temperature uniformity of a sample to be detected is obviously improved, and the accuracy of the method is improved. And the sample pretreatment is simple and quick, the period of analysis and detection is greatly shortened, and the efficiency can be greatly improved when the method is used for screening industrial thermal cracking raw materials.

4. The invention provides a laser pyrolysis analysis and detection method, which can adjust and modify an analysis and detection system according to research needs, is convenient and flexible, and enables researchers to fully obtain required pyrolysis information through one set of equipment.

5. The invention provides a laser pyrolysis analysis and detection method, most of the existing laser pyrolysis detection methods can only obtain information of solid products or information of gas products, and the method can obtain detection information of the gas products and the solid products through one-time detection.

6. The invention provides a laser pyrolysis analysis and detection method, the existing laser pyrolysis detection method can not measure the temperature of a sample to be detected, the method can observe the accurate temperature of the sample in the laser pyrolysis process in real time, and valuable information is provided for relevant research

Detailed Description

The technical solutions of the present invention will be described clearly and completely below, and it should be apparent that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

A suspension bed hydrogenation pilot-scale tail oil is selected as the raw material of the embodiment, the cutting temperature of the tail oil is 500 ℃, so the tail oil is different from industrial products of the suspension bed hydrogenation tail oil, and the properties of the suspension bed hydrogenation tail oil after conventional dehydration and mechanical impurity removal pretreatment are shown in the table 1.

TABLE 1

Example a laser pyrolysis reaction conditions are shown in table 2.

TABLE 2

Carbon dioxide laser power, W	130
		Irradiation time, s	5
Sample mass, mg	1.05
		Thermal cracking atmosphere	Argon gas
Carbon dioxide laser mode	(Continuous)

Example the temperature of the samples for laser pyrolysis is shown in table 3.

TABLE 3

Example a laser pyrolysis gas product yield is shown in table 4.

TABLE 4

Gaseous products	Yield and content of
		C2H4	13.91256
C2H6	1.385279
		C2H2	0.208392
CH4	10.01925
		H2	0.56313
CO2	0.025288
		CO	0.023433

Example a solid product of laser pyrolysis has the properties shown in table 5.

TABLE 5

Example two

The properties of the black mountain coal obtained by drying and pretreating the black mountain coal as the raw material in this example are shown in table 6.

TABLE 6

Item	Coal for mountain black
		Fixed carbon, w%	49.38
Ash content, w%	17.76
		Volatile content, w%	17
Carbon content, m%	93.35
		Hydrogen content, m%	5.95
Oxygen content, m%	21.27
		Nitrogen content, m%	1.88
Sulfur content, m%	0.58
		Constant volume high calorific value MJ/kg	25.65
Constant volume low heating value MJ/kg	24.66
		Volume mean diameter, μm	43.18
Porosity, vol%	24.39

The reaction conditions for the laser pyrolysis of example two are shown in table 7.

TABLE 7

Carbon dioxide laser power, W	100
		Irradiation time, s	3
Sample mass, mg	3.19
		Thermal cracking atmosphere	60 vol% Nitrogen +40 vol% Hydrogen
Carbon dioxide laser mode	(Continuous)

The sample temperatures for laser pyrolysis of example two are shown in table 8.

TABLE 8

Laser irradiation time, s	Temperature, C
		0.038	1000
0.113	2280
		0.213	2420
0.313	2460
		0.413	2480
0.513	2480
		0.613	2500
0.723	2520
		0.828	2540
1.567	2560
		1.661	2580
1.748	2600
		1.8	2620
1.865	2640
		5	2640

The yields of gaseous products from laser pyrolysis of example two are shown in table 9.

TABLE 9

Gaseous products	Yield and content of
		C2H4	1.11
C2H6	0.20
		C2H2	1.63
CH4	1.46
		H2	2.71
CO2	2.33
		CO	25.63

Example two the properties of the solid product from laser pyrolysis are shown in table 10.

Watch 10

Item	Solid product of coal from Heishan mountain
		Fixed carbon, w%	78.2
Ash content, w%	21.8
		Volatile content, w%	0
Carbon content, m%	97.07
		Hydrogen content, m%	0.39
Oxygen content, m%	0.7
		Nitrogen content, m%	1.26
Sulfur content, m%	0.38

EXAMPLE III

The properties of the waste LDPE produced by Shanghai petrochemical industry are shown in Table 11.

TABLE 11

The reaction conditions for the third laser pyrolysis of example are shown in table 7.

TABLE 12

Carbon dioxide laser power, W	130
		Irradiation time, s	5
Sample mass, mg	3.19
		Thermal cracking atmosphere	Argon gas
Carbon dioxide laser mode	(Continuous)

The sample temperatures for the third laser thermal cracking of the examples are shown in Table 13.

Watch 13

The yields of gaseous products from the three laser thermal cracking of the example are shown in table 14.

TABLE 14

Gaseous products	Yield and content of
		C2H4	30.21
C2H6	0.42
		C2H2	3.41
CH4	16.62
		H2	2.27
CO2	0.71
		CO	0.86

Example three laser pyrolysis solid product properties are shown in table 15.

Watch 15

Comparative example

The common electric heating device has a limited heating area, the temperature distribution in the area is uneven, and a low-boiling-point liquid sample leaves the hot area after being gasified and enters the area with a relatively low temperature to stop thermal cracking, so that a large amount of tar products are generated, which is seriously inconsistent with the actual production process. Sample heating rate 10 in laser thermal cracking method⁴The temperature is higher than the second temperature, so the phenomenon can be effectively avoided, and the sample is cracked for the second time. In the comparative example, a suspended bed hydrogenated tail oil in the first tubular furnace thermal cracking example was selected, and the sample pretreatment method was the same as in the first example, and the sample properties were also the same.

Comparative example tubular furnace pyrolysis reaction conditions are shown in table 7.

TABLE 16

Final temperature,. degree.C	1600
		Rate of temperature rise, s	≈10³
Sample mass, mg	982
		Thermal cracking atmosphere	Argon gas

The sample temperature in the tube furnace in the comparative example was not measurable over time. The yields of the thermal cracking products in the tubular furnace in the comparative example are shown in Table 17.

TABLE 17

The results of the analysis of tar in the comparative example are shown in Table 18.

Watch 18

The analysis results of the solid product in the comparative example are shown in Table 19.

Watch 19

Claims

2. The method of claim 1, wherein the apparatus of the laser thermal cracking method comprises a carbon dioxide laser heating system, a two-color infrared temperature measuring system, a specially designed reactor, a gas product analysis system and a gas supply system.

3. The method according to any one of claims 1 and 2, wherein the carbon dioxide laser power is between 1W and 200W, the laser mode comprises single-point irradiation, pulse irradiation and continuous irradiation, and the laser power error is required to be within ± 5%. The timer is connected with and controls the irradiation and termination of the carbon dioxide laser, and the timing precision requirement reaches 0.1 s.

4. The method according to any one of claims 1 to 3, wherein the sample tray is made of a material which is resistant to high temperature, does not chemically react with the sample under high temperature conditions, and conducts heat rapidly, such as stainless steel, tungsten, and the like. The sample plate was a bottomed hollow cylinder having an inner diameter of 4mm, an outer diameter of 6mm, a bottom thickness of 1mm and a total height of 3 mm.

5. The method according to any one of claims 1 to 4, wherein the sample injection mass is in the range of 0.1mg to 10mg, and the sample pretreatment and injection method comprises the following steps:

6. A method according to any one of claims 1 to 5, wherein the reactor is made of a stainless steel chamber with an internal diameter of 10mm, and the sides of the chamber are provided with gas inlets and outlets by means of two opposite gas paths, the specifications of which are matched with those of the rest of the apparatus. The height of the inner part of the reaction chamber is 5mm to 10mm, so that the blowing dead zone in the subsequent gas product detection process is reduced, the calculation precision of the yield is improved, the sample to be detected is prevented from being too close to the lens, and the influence of the sample thermal cracking process on the lens is avoided.

7. The method as claimed in any one of claims 1 to 6, wherein a lens with a high transmittance in a wavelength range of infrared temperature measurement and a carbon dioxide laser with a thickness of 3mm such as zinc selenide is arranged at the top of the reactor and is used for transmitting laser and infrared temperature measurement, an antireflection film is coated on the surface of the lens, and the actual measured transmittance is required to be more than 90%.

8. The method of any one of claims 1 to 7, wherein the reactor is sealed at the junction with a silicone O-ring seal adjacent the lens and the remainder with a stainless steel cuff to enable the entire reactor to be sealed at a pressure of 400 kPa.

9. The method according to any one of claims 1 to 8, wherein the infrared thermometer is calibrated to accurately measure the temperature of the sample before the experiment, and the infrared light radiated from the sample can accurately enter the probe of the two-color infrared thermometer. If the infrared thermometer is affected by the lens at the top of the reactor, the influence of the lens is counteracted by adjusting the built-in parameters of the infrared thermometer through the standard temperature.

10. The method according to any one of claims 1 to 9, wherein the infrared thermometer has a temperature measurement frequency higher than 10/s, a signal delay of less than 10s, a temperature measurement range of 1000 ℃ to 3000 ℃, a temperature measurement error of less than 3%, and a temperature curve during the whole cracking process is recorded by a matched electronic device.

11. The method according to any one of claims 1 to 10, wherein the reactor is purged with a purge gas to create a target atmosphere before cracking,

(2) Oxidizing gas such as air, oxygen, water vapor, etc

(3) Inert gases such as nitrogen, argon, helium, etc

12. The method of any of claims 1-11, wherein the reactor purge gas is controlled to a purge gas flow rate of less than 100mL/min to avoid blowing off the sample and changing the initial gas pressure during laser thermal cracking.

13. The method according to any one of claims 1 to 12, wherein the reactor is directly connected to a detection device such as a gas chromatograph or a mass spectrometer and is controlled by a set of valve piping system and a corresponding program, and the sample introduction and detection of the detection device are automatically performed after the program is started.

14. The method according to any one of claims 1 to 13, wherein the working gas required by the detection system is provided by a gas supply part in the system, and for gas chromatography, a hydrogen flame ionization detector is usually matched to accurately analyze the concentration of the small molecular hydrocarbons such as methane, ethylene, acetylene, ethane and the like in the cracked gas, and a thermal conductivity detector is combined to analyze the concentration of gases such as hydrogen, carbon monoxide, carbon dioxide and the like, so that compressed air, carrier gas and hydrogen are required to be used as the working gas.

15. The method according to any one of claims 1 to 14, wherein the effective volume of the reactor is calculated by a geometric method or an internal standard method, which requires calculation of an internal standard substance concentration peak area curve by gas chromatography and then interpolation, to obtain an accurate value for quantitative calculation of the product yield.

16. The method according to any one of claims 1 to 15, wherein a suitable filtering or cooling device is provided in the middle of or in one of the reactor and the detection part to prevent solid particles and low boiling point substances from entering the detection system, thereby protecting the precision instruments in the detection system and accurately calculating the mass change.

17. The method of any one of claims 1 to 16, wherein the detection system comprises a gas chromatograph and the carrier gas is selected from argon if the analysis of hydrogen is required and argon, hydrogen and helium if the analysis of hydrogen is not required.

18. The method of any one of claims 1-17, wherein the reactor is closed during thermal cracking, so as to avoid the escape of laser thermal cracking products and gases in the thermal cracking atmosphere, which would affect the detection accuracy.

19. The method of any of claims 1-18, wherein the carbon dioxide laser is focused by a lens according to the energy density required for thermal cracking, and the relative position of the lens and the sample is calculated to avoid excessive energy density ablation of the sample disk and the reactor.