Process control detection device and method for producing maleic anhydride through butane oxidation

Abstract

The invention discloses a process control and detection device for producing maleic anhydride through butane oxidation, which adopts the gas chromatography principle and comprises a valve group, a gas inlet pipe, a gas outlet pipe, a gas inlet pipe, a gas outlet pipe, a gas inlet pipe and a gas outlet pipe, the valve group is provided with a plurality of multi-channel valves and is used for controlling formation of permanent gas channels and hydrocarbon channels; and the plurality of chromatographic columns are used for separating mixed gas of carbon monoxide, oxygen, carrier gas and carbon dioxide in the permanent gas channel and separating hydrocarbon components with different molecular weights in the hydrocarbon channel. The invention further discloses a process control detection method for producing maleic anhydride through butane oxidation. The detection device is applied to sample component separation and purity detection. By adopting the device and the method disclosed by the invention, various hydrocarbon components and permanent gas can be effectively separated through the matching of the valve group and the plurality of chromatographic columns, so that the purity of each component is accurately determined, and the interference of a matrix component on a target component is effectively avoided.

Description

Technical Field

[0001] The invention relates to the technical field of using gas chromatography to quickly detect control indicators in a production process, and in particular to a process control detection device and method for producing maleic anhydride by oxidation of butane. Background Art

[0002] Demand for maleic anhydride, a raw material for biodegradable materials, continues to rise. Maleic anhydride, also known as maleic anhydride, 2,5-furandione, is a key raw material used in the production of unsaturated polyester resins and alkyd resins. It is also a comonomer in polymaleic anhydride and maleic anhydride-styrene copolymers, and an organic chemical raw material for the production of fumaric acid and tetrahydrofuran.

[0003] There are two routes for synthesizing maleic anhydride: benzene oxidation and n-butane oxidation. Benzene oxidation is a relatively expensive process for producing maleic anhydride. Its raw material, pure benzene, is significantly affected by crude oil prices, resulting in reduced supply and persistently high prices. Furthermore, it faces environmental pressures and has been largely phased out within the industry. The n-butane oxidation process, however, has gradually become the mainstream technology in the industry due to its advantages, including high n-butane utilization, lower price, reduced raw material consumption, and minimal environmental impact. Rapid analysis of raw materials and products is a key step in the development of butane oxidation-based maleic anhydride, guiding process improvements.

[0004] When producing maleic anhydride through the oxidation of n-butane, the feed gas typically contains n-butane, oxygen, and nitrogen. Nitrogen itself does not participate in the chemical reaction and only serves to dilute the feed gas. Tail gas treated by water absorption typically contains unreacted butane, oxygen, and deep oxidation products such as carbon monoxide and carbon dioxide, as well as other trace impurities. Nitrogen, oxygen, carbon monoxide, and carbon dioxide in the gas mixture are considered permanent gases, and some of these gases have a small polarity difference from butane, making them difficult to separate. Furthermore, carbon dioxide is strongly and irreversibly adsorbed on most molecular sieve columns, making it difficult to separate all components using a single column using gas chromatography.

[0005] Among the existing analytical methods, for example, "Study on Propane Oxidation to Acrylic Acid over VPO Catalyst, Acta Petrolei Sinica (Petroleum Processing), 1998, 14(3)", two chromatographs and multiple detectors (TCD or FID) are used, and two chromatographic columns are switched, etc., in combination with chemical titration. This type of method occupies a large amount of equipment, has a long analysis time, and is cumbersome to operate. Another example is "Dual Column Tandem Chromatography for Single-Shot Analysis of Methane Partial Oxidation to Synthesis Gas Products, Analytical Testing Technology and Instruments, 1998.4(2)", a single chromatograph equipped with a TCD detector is used, combined with a multi-dimensional chromatographic column switching method. However, this type of method has high requirements for instrument precision and automation level, low reproducibility, and when performing kinetic processing, the concentration of maleic anhydride must be calculated in combination with chemical titration, resulting in a long analysis cycle. Another example is "Chromatographic Analysis Method for Gas Phase Components of Maleic Anhydride Oxidation to Butane, Petroleum and Natural Gas Chemical Industry, 2002, 31(2)", a single chromatograph equipped with a TCD detector is used, and two chromatographic columns are connected in parallel. However, although this type of method has been improved on the basis of the previous two methods, it still requires two injections to complete the analysis and uses TCD analysis, which has poor sensitivity.

[0006] Therefore, there is an urgent need for a detection device and method with strong specificity and anti-interference ability that can accurately measure the raw materials and process gas phase components in the process of butane oxidation to produce maleic anhydride.

[0007] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0008] The object of the present invention is to provide a process control detection device and method for producing maleic anhydride by butane oxidation. By adopting the principle of gas chromatography and cooperating with a valve group and multiple chromatographic columns, the device can effectively separate various hydrocarbon components and permanent gases, and then accurately determine the purity of each component, while effectively avoiding the interference of matrix components on target components.

[0009] To achieve the above-mentioned objectives, according to a first aspect of the present invention, there is provided a process control and detection device for producing maleic anhydride by oxidation of butane, which adopts the principle of gas chromatography and comprises: a valve group provided with a plurality of multi-channel valves for controlling the formation of permanent gas channels and hydrocarbon channels; a plurality of chromatographic columns for separating a mixed gas of carbon monoxide, oxygen, carrier gas and carbon dioxide in the permanent gas channel, and separating hydrocarbon components of different molecular weights in the hydrocarbon channel.

[0010] Furthermore, in the above technical solution, the multi-channel valve includes: a first valve, which is a ten-way gas sampling valve with a pre-column backflushing function; a second valve, which is a six-way valve with a column isolation function; a third valve, which is a six-way gas sampling valve; and a fourth valve, which is a six-way valve with a sequencing function; the first valve and the second valve are used in conjunction with each other to control the formation of a permanent gas channel; and the third valve and the fourth valve are used in conjunction with each other to control the formation of a hydrocarbon channel.

[0011] Furthermore, in the above technical solution, the chromatographic columns may include: a first chromatographic column, which is a divinylbenzene and styrene polymer chromatographic column, used to separate C3 and above compounds from the permanent gas; a second chromatographic column, which is a divinylbenzene and styrene polymer chromatographic column, used to separate carbon dioxide from carbon monoxide, oxygen, and carrier gas in the permanent gas; a third chromatographic column, which is a 5A molecular sieve porous layer open chromatographic column, used to separate carbon monoxide, oxygen, and carrier gas; a fourth chromatographic column, which is a dimethyl polysiloxane chromatographic column, used to separate C6 and above hydrocarbon compounds; a fifth chromatographic column, which is an alumina chromatographic column, used to separate C5 and below hydrocarbon compounds.

[0012] Furthermore, in the above technical solution, the first chromatographic column and the second chromatographic column can be respectively connected to the corresponding channels of the first valve. When the first valve is in the open state, the first chromatographic column and the second chromatographic column are in the conductive state; when the first valve is in the closed state, the first chromatographic column and the second chromatographic column are in the non-conductive state. At this time, the first chromatographic column performs backflushing, and the second chromatographic column separates carbon dioxide from carbon monoxide, oxygen, and carrier gas.

[0013] Furthermore, in the above technical solution, the third chromatographic column can be connected to the corresponding channel of the second valve. When the second valve is in the open state, the third chromatographic column is in the isolated state, and the separated carbon dioxide from the second chromatographic column is detected; when the second valve is in the closed state, the carbon monoxide, oxygen, and carrier gas in the third chromatographic column are detected.

[0014] Furthermore, in the above technical solution, the fourth chromatographic column and the fifth chromatographic column can be connected to corresponding channels of the fourth valve respectively. When the fourth valve is in the open state, hydrocarbon compounds can be separated on the fourth chromatographic column and the fifth chromatographic column in sequence.

[0015] Furthermore, in the above technical solution, the detection device of the present invention is a gas chromatograph, which also includes: an FID detector, which is used to analyze the separated C1-C5 hydrocarbons; a TCD detector, whose reference gas is designed to be helium, which is used to analyze carbon monoxide, oxygen, carrier gas and carbon dioxide separated from the permanent gas.

[0016] According to a second aspect of the present invention, a process control detection method for producing maleic anhydride by oxidation of butane is provided, wherein any one of the aforementioned detection devices is used to perform sample component separation and purity detection.

[0017] Furthermore, in the above technical solution, the samples may be: standard gas, butane raw gas sample and reaction process gas.

[0018] Furthermore, in the above technical solution, during the separation of sample components, the programmed temperature conditions can be specifically as follows: initial temperature 60-80°C, hold for 0-1 min; heat to 80-100°C at a rate of 10-20°C / min, hold for 0-1 min; heat to 150-190°C at a rate of 20-30°C / min, hold for 0-5 min; cool to 60-100°C at a rate of 30-50°C / min, hold for 0-1 min.

[0019] Furthermore, in the above technical solution, the vaporization temperature in the detection method may be 100-150°C; and the detection temperature may be 200-280°C.

[0020] Furthermore, in the above technical solution, the split ratio in the detection method can be 20:1-150:1.

[0021] Furthermore, in the above technical solution, the sample injection volume can be controlled by a quantitative loop, and the injection volume can be 1-5 mL; the detection and analysis time can be 7-10 min.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The device of the present invention can effectively separate various hydrocarbons and permanent gases and accurately measure the purity of each component in a gas chromatograph through the cooperation of a valve group and multiple chromatographic columns. It is particularly suitable for process control of butane oxidation to produce maleic anhydride, and has strong specificity. It can also accurately measure the raw material and process gas phase components in the butane oxidation process to produce maleic anhydride. Some impurities, such as C3 and above impurities, may be generated during the reaction. Through the backflush setting, C3 and above components can be backflushed in time to avoid affecting the analysis, effectively preventing interference of matrix components on target components, and having strong anti-interference ability.

[0024] 2) The device and method of the present invention can obtain good chromatographic peak shape and detection limit. Experiments have shown that the lower limit can reach 100 ppm, while extending the service life of the detector;

[0025] 3) The present invention adopts a reasonable injection volume and vaporization chamber temperature to ensure that the sample is instantly and completely vaporized without causing sample decomposition, achieving the specified separation requirements and within the allowable range of linear response; adopting reasonable programmed temperature conditions, each component can achieve satisfactory separation and sensitivity, which helps to achieve better separation of each component in a short time, making subsequent analysis faster and more accurate;

[0026] 4) The detection device of the present invention occupies little space and equipment, and the detection method can simply, quickly, and accurately analyze the contents of carbon monoxide, carbon dioxide, oxygen, nitrogen, hydrogen, hydrocarbons, and trace impurities in the process of butane oxidation to produce maleic anhydride, and is suitable for laboratory research and development and industrial rapid online analysis.

[0027] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other purposes, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The diagram is a schematic diagram of the construction of a valve group and a chromatographic column in a process control and detection device for producing maleic anhydride by butane oxidation according to the present invention.

[0029] Figure 2-A It is a schematic diagram of the channel when the first valve of the present invention is in a closed state.

[0030] Figure 2-B It is a schematic diagram of the channel when the first valve of the present invention is in an open state.

[0031] Figure 3-A It is a schematic diagram of the channel when the second valve of the present invention is in a closed state.

[0032] Figure 3-B It is a schematic diagram of the channel when the second valve of the present invention is in an open state.

[0033] Figure 4-A It is a schematic diagram of the channel when the third valve of the present invention is in a closed state.

[0034] Figure 4-B It is a schematic diagram of the channel when the third valve of the present invention is in an open state.

[0035] Figure 5-A Schematic diagram of the channel when the fourth valve of the present invention is in a closed state.

[0036] Figure 5-B Schematic diagram of the channel when the fourth valve of the present invention is in an open state.

[0037] Figure 6This is a schematic diagram of gas composition analysis during the process of producing maleic anhydride by butane oxidation according to the present invention. DETAILED DESCRIPTION

[0038] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0039] Unless expressly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising” will be understood to include the stated elements or components but not to exclude other elements or components.

[0040] In this document, for ease of description, spatially relative terms such as "below," "beneath," "down," "above," "above," etc. may be used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that the spatially relative terms are intended to encompass different orientations of an object in use or operation in addition to the orientation depicted in the drawings. For example, if the object in the figure is turned over, the element described as being "below" or "below" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both below and above directions. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatially relative terms used herein should be interpreted accordingly.

[0041] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to limit specific positions or relative relationships. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable with each other.

[0042] like Figure 1 As shown, the present invention provides a process control and detection device for butane oxidation to produce maleic anhydride. The device is designed as a gas chromatograph, employing the principles of gas chromatography. It includes at least a valve manifold and multiple chromatographic columns. The combination of these two components effectively separates the components of butane feed gas and process gas used to produce maleic anhydride. The device also includes an FID detector and a TCD detector for detecting the separated permanent gases and hydrocarbons, respectively. The valve manifold is equipped with multiple multi-channel valves for controlling the formation of permanent gas channels and hydrocarbon channels. Multiple chromatographic columns are used to separate the mixed gas of carbon monoxide, oxygen, carrier gas, and carbon dioxide in the permanent gas channel and to separate hydrocarbon components of different molecular weights in the hydrocarbon channel. The present invention, through the combination of the valve manifold and multiple chromatographic columns in a single gas chromatograph, is particularly suitable for process control of butane oxidation to produce maleic anhydride, offering high specificity. It can also accurately measure the components of the feedstock and process gas phases during butane oxidation to produce maleic anhydride, with strong anti-interference capabilities.

[0043] Further Figure 1 As shown, the multi-channel valve of the present invention can use four, including the first valve, the second valve, the third valve and the fourth valve (shown as valve 1#, valve 2#, valve 3# and valve 4# respectively in the figure). Among them, the first valve is a ten-way gas sampling valve with a pre-column backflush venting function (refer to Figure 2-A and 2-B ). The second valve, the third valve and the fourth valve can all be six-way valves. Specifically, the second valve is a six-way valve with column isolation function (refer to Figure 3-A and 3-B ); The third valve is a six-way gas sampling valve (reference Figure 4-A and 4-B ), specifically, it can be a gas sampling six-way valve upstream of the capillary inlet; the fourth valve is a six-way valve with a sequencing function (reference Figure 5-A and 5-B The first valve and the second valve of the present invention cooperate to control the formation of a permanent gas channel; the third valve and the fourth valve cooperate to control the formation of a hydrocarbon channel.

[0044] Further Figure 1 Shown, chromatographic column of the present invention can use five, comprise the first chromatographic column, the second chromatographic column, the third chromatographic column, the fourth chromatographic column and the fifth chromatographic column.Wherein, the first chromatographic column is divinylbenzene and styrene polymer chromatographic column, preferably 0.5M HayeSep Q 80 / 100, for separating C3 and above compound and described permanent gas, also be about to all C3 and heavier compound with the gas of hydrogen separation.The second chromatographic column is divinylbenzene and styrene polymer chromatographic column, preferably 6Ft HayeSep Q 80 / 100, for separating the carbon dioxide in the permanent gas with carbon monoxide, oxygen, carrier gas, also be separated carbon dioxide and other lighter gases.The third chromatographic column is 5A molecular sieve porous layer opening chromatographic column, preferably 8Ft MolSieve 5A 60 / 80, for separating carbon monoxide, oxygen, carrier gas (generally using nitrogen).The fourth chromatographic column is dimethylpolysiloxane chromatographic column, preferably DB-1, for separating C6 and above hydrocarbon compounds. The fifth chromatographic column is an alumina chromatographic column, preferably HP-PLOT / Al2O3, which is used to separate hydrocarbon compounds of C5 and below.

[0045] Further Figure 1As shown, the present invention utilizes an FID detector and a TCD detector, both of which are built into a gas chromatograph. The FID detector can be used to analyze separated C1-C5 hydrocarbons, etc. The TCD detector, designed with helium as the reference gas, can be used to analyze carbon monoxide, oxygen, carrier gas, and carbon dioxide separated from permanent gases.

[0046] Further Figure 2-A and 2-B As shown, in the detection device of the present invention, the first chromatographic column and the second chromatographic column are respectively connected to the corresponding channels of the first valve. Specifically, the first chromatographic column can be connected to the channels 2 and 5 of the first valve, and the second chromatographic column can be connected to the channel 6. When the first valve is in the open state, as shown in FIG. Figure 2-B As shown, the first chromatographic column and the second chromatographic column are in the conducting state, and the sample gas can pass through the first chromatographic column and the second chromatographic column respectively under the drive of the carrier gas. At this time, the mixture in the sample gas is distributed in the first chromatographic column and the second chromatographic column. The components with lighter molecules are first separated from the first chromatographic column and enter the second chromatographic column for further separation, and all C3 and heavier molecular components are retained in the first chromatographic column; when the first valve is in the closed state, as shown Figure 2-A As shown, the first chromatographic column and the second chromatographic column are in a non-conducting state. At this time, the first chromatographic column performs backflushing, and the second chromatographic column separates carbon dioxide from carbon monoxide, oxygen, and carrier gas. That is, all C3 and heavier molecular components are backflushed out of the first chromatographic column by the carrier gas of channel 4, and the components that have reached the second chromatographic column (i.e., carbon monoxide, oxygen, and carrier gas) are not affected.

[0047] Further Figure 3-A and 3-B As shown, the third chromatographic column is connected to the corresponding channels of the second valve. Specifically, the third chromatographic column can be connected to channels 3 and 4 of the second valve. When the second valve is open, the third chromatographic column is isolated, and the separated carbon dioxide from the second chromatographic column (which has been well separated on the second chromatographic column) enters the TCD detector for detection. When the second valve is closed, the carbon monoxide, oxygen, and carrier gas locked in the third chromatographic column enter the TCD detector for detection.

[0048] Further Figure 4-A and 4-B As shown, the third valve is a gas sampling valve and is not directly connected to the chromatographic column. Opening the third valve allows the sample gas filling the quantitative loop to pass through channels 3 and 4 of the third valve and enter the fourth valve under the drive of the carrier gas. Figure 5-A and 5-BAs shown, the fourth and fifth chromatographic columns are respectively connected to corresponding channels of the fourth valve. Specifically, the fourth chromatographic column can be connected to channel 4 of the fourth valve, and the fifth chromatographic column can be connected to channels 2 and 6 of the fourth valve. When the fourth valve is in the open state, hydrocarbon compounds can be separated in the fourth and fifth chromatographic columns in sequence.

[0049] The present invention also provides a process control detection method for producing maleic anhydride by butane oxidation, which uses the aforementioned detection device to perform sample component separation and purity detection. The sample gas can be a standard gas, a butane raw gas sample, and a reaction process gas. During the sample component separation process of the present invention, the programmed temperature conditions can be specifically as follows: initial temperature 60-80°C, maintained for 0-1min; heating to 80-100°C at a rate of 10-20°C / min, maintained for 0-1min; heating to 150-190°C at a rate of 20-30°C / min, maintained for 0-5min; cooling to 60-100°C at a rate of 30-50°C / min, maintained for 0-1min. By designing such temperature conditions, it is helpful to achieve better separation of the components in a short time, making subsequent analysis faster and more accurate.

[0050] Furthermore, the vaporization temperature in the detection method (i.e., the vaporization chamber temperature, the vaporization chamber is not shown in the figure) can be 100-150°C, preferably 120°C; the detection temperature (i.e., the detector temperature) is 200-280°C, preferably 280°C. The split ratio in the detection method is 20:1-150:1, preferably 100:1. The injection volume of the sample is controlled by a quantitative loop, and the injection volume can be 1-5mL, preferably 1mL; the detection analysis time is set to 7-10min, preferably 8min. The analysis method of the present invention can adopt the area percentage method, the normalization method and the external standard method, preferably the external standard method.

[0051] Example 1

[0052] The detection device of this embodiment uses a gas chromatograph: Agilent 7890A chromatography system and workstation from the United States. Five chromatographic columns: 0.5M HayeSep Q 80 / 100, 6Ft HayeSep Q 80 / 100, 8Ft MolSieve 5A 60 / 80, DB-1, and HP-PLOT / Al2O3.

[0053] Program heating conditions: initial temperature 60 °C, hold for 1 min, heat to 80 °C at a rate of 20 °C / min, hold for 0 min, heat to 190 °C at a rate of 30 °C / min, hold for 0 min, cool to 100 °C at a rate of 45 °C / min, hold for 0.5 min.

[0054] The sample gas in this embodiment is standard gas.

[0055] For the permanent gas channel, the gas enters the channel 10 of the first valve through the injection port to fill the quantitative loop, and at the same time enters the third valve through the channel 8 of the first valve, and passes through the channels 2 and 3 of the third valve to fill the quantitative loop, such as Figure 2-A and 4-A At 0.1s, the first and third valves are opened simultaneously. Driven by the carrier gas, the standard gas in the first valve passes through channel 1, channel 2, the first chromatographic column, channel 5, channel 6, the second chromatographic column, and then enters the second valve. Figure 2-B At this time, the mixture of the standard gas is distributed in the first column and the second column. The components with lighter molecules are separated from the first column and enter the second column for further separation. All C3 and heavier components are retained in the first column. At 1.25 minutes, the first valve is closed (reference Figure 2-A ), all C3 and heavier components are back-flushed out of the first chromatographic column by the carrier gas of channel 4, and the components that have reached the second chromatographic column are not affected. The components that have passed through the second chromatographic column reach the second valve, and some components (carbon monoxide, oxygen and nitrogen) that come out of the second chromatographic column are first transferred to the third chromatographic column through channel 5 for separation (refer to Figure 3-A ). At 1.55 min, the second valve opens, and the component (carbon dioxide) that has been well separated on the second chromatographic column directly enters the TCD for detection, while the other components are locked in the third chromatographic column (reference Figure 3-B At 4.2 minutes, the second valve is closed, and the components locked in the third chromatographic column (carbon monoxide, oxygen, and nitrogen) enter the TCD through channels 3 and 2 in sequence for detection (reference Figure 3-A ). At this point, the gas in the permanent gas channel has been detected.

[0056] For the hydrocarbon channel, the third valve is opened for 0.1s and the sample gas filling the quantitative loop passes through channels 3 and 4 and enters the fourth valve. Figure 4-B 0.55s The sample gas reaches the channel 5 of the fourth valve (reference Figure 5-A ), open the fourth valve (reference Figure 5-B The sample gas is separated in the fourth and fifth chromatographic columns (butane) and then enters the FID detector for detection. The third valve closes at 1 minute, and the fourth valve closes at 7 minutes. At this point, the gas in the hydrocarbon channel is completely detected.

[0057] The standard gas in the cylinder was connected to the detection device of the present invention and was continuously introduced three times, including butane, nitrogen, oxygen, carbon monoxide, carbon dioxide and hydrogen. The detection time was 8 minutes, and the %RSD was less than 2.0, which met the requirements.

[0058] Example 2

[0059] This embodiment uses the same gas chromatograph, valve group, chromatographic column and detector as in Example 1, and the programmed temperature conditions are also the same as in Example 1.

[0060] Different from Example 1, the sample gas in this example is a butane raw gas sample.

[0061] The component separation, detection and other analysis processes are also the same as in Example 1, and are briefly described below: the first valve adopts a ten-way injection backflush valve, which performs sample pre-separation while introducing the gas sample, and backflushes C3 and above components through the first chromatographic column, allowing the permanent gas components to enter the second chromatographic column. After the permanent gas components enter the third chromatographic column for separation, the second valve is switched to allow oxygen, nitrogen, carbon monoxide and carbon dioxide to flow out in sequence on the TCD peak. The fourth valve adopts a six-way sequence valve, which is responsible for backflush C6 and above components and the earliest peak. The third valve adopts a six-way injection valve, which is responsible for introducing the sample; the hydrocarbon gas enters the FID detector through the third valve and the fourth valve to analyze the n-butane gas.

[0062] The gas collection bag was connected to the detection device of the present invention and butane, nitrogen, oxygen, carbon monoxide and carbon dioxide were introduced three times continuously. The detection time was 8 minutes and the %RSD was less than 2.0, which met the requirements.

[0063] Example 3

[0064] This embodiment uses the same gas chromatograph, valve group, chromatographic column and detector as in Example 1, and the programmed temperature conditions are also the same as in Example 1.

[0065] Different from Example 1, the sample gas in this embodiment is reaction process gas.

[0066] The component separation, detection and other analysis processes are also the same as in Example 1, and are briefly described below: the first valve uses a ten-way injection backflush valve to pre-separate the sample while introducing the gas sample, and backflush C3 and above components through the first chromatographic column to allow the permanent gas components to enter the second chromatographic column. After the permanent gas components enter the third chromatographic column for separation, switch the second valve to allow oxygen, nitrogen, carbon monoxide and carbon dioxide to flow out in sequence and peak on the TCD. The fourth valve uses a six-way sequence valve, which is responsible for backflush C6 and above components and the earliest peak. The third valve uses a six-way injection valve, which is responsible for introducing samples; hydrocarbon gas enters the FID detector through the third valve and the fourth valve to analyze the n-butane gas. For gas composition analysis of the process of butane oxidation to produce maleic anhydride, see Figure 6 .from Figure 6As can be seen from the figure, the apparatus and method of the present invention can achieve good chromatographic peak shape and a detection limit of 100 ppm. Experimental results show that the detection limit can reach 100 ppm. The reaction process may produce some impurities, such as C3 and above impurities. The backflush setting can promptly backflush C3+ and above components to avoid affecting the analysis and effectively prevent interference of matrix components with the target components.

[0067] The gas collection bag was connected to the detection device of the present invention and butane, nitrogen, oxygen, carbon monoxide and carbon dioxide were introduced three times continuously. The detection time was 8 minutes and the %RSD was less than 2.0, which met the requirements.

[0068] Comparative Example 1

[0069] Two chromatographs, each equipped with a TCD and FID detector, were used to analyze the mixed standard gas. The test lasted 50 minutes, and the %RSD of each component in the sample gas was less than 5.0.

[0070] Comparative Example 2

[0071] A single chromatograph equipped with a TCD detector and multi-dimensional column switching were used to analyze the mixed standard gas. The test lasted 50 minutes, and the %RSD of each component in the sample gas was less than 5.0.

[0072] Comparative Example 3

[0073] A single chromatograph equipped with a TCD detector and two chromatographic columns in parallel were used. Two separate injections were performed using different injection valves and quantitative tubes to analyze the mixed standard gas. The test lasted 15 minutes, and the %RSD of each component in the sample gas was less than 4.0.

[0074] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise form disclosed, and it is apparent that many changes and variations are possible in light of the foregoing teachings. The exemplary embodiments are selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and variations. Any simple modifications, equivalent variations, and modifications made to the exemplary embodiments described above are intended to fall within the scope of protection of the present invention.

Claims

1. A process control and detection device for producing maleic anhydride by oxidation of butane, using the principle of gas chromatography, characterized in that: include: A valve group provided with a plurality of multi-channel valves for controlling the formation of permanent gas channels and hydrocarbon channels; The chromatographic columns are multiple in number and are used to separate the mixed gas of carbon monoxide, oxygen, carrier gas and carbon dioxide in the permanent gas channel, and to separate hydrocarbon components of different molecular weights in the hydrocarbon channel.

2. The process control and detection device for producing maleic anhydride by butane oxidation according to claim 1, characterized in that: The multi-channel valve comprises: The first valve is a ten-way gas sampling valve with a pre-column backflush function; The second valve is a six-way valve with column isolation function; The third valve is a six-way gas sampling valve; The fourth valve is a six-way valve with a sequencing function; The first valve and the second valve cooperate to control the formation of the permanent gas channel; the third valve and the fourth valve cooperate to control the formation of the hydrocarbon channel.

3. The process control and detection device for producing maleic anhydride by butane oxidation according to claim 2, characterized in that: The chromatographic column comprises: The first chromatographic column is a divinylbenzene and styrene polymer chromatographic column, which is used to separate C3 and above compounds and the permanent gas; a second chromatographic column, which is a divinylbenzene and styrene polymer chromatographic column, for separating carbon dioxide from carbon monoxide, oxygen, and carrier gas in the permanent gas; A third chromatographic column, which is a 5A molecular sieve porous layer open chromatographic column, is used to separate the carbon monoxide, oxygen, and carrier gas; The fourth chromatographic column is a dimethylpolysiloxane chromatographic column used for separating hydrocarbon compounds of C6 and above; The fifth chromatographic column is an alumina chromatographic column, which is used to separate hydrocarbon compounds of C5 and below.

4. The process control and detection device for producing maleic anhydride by butane oxidation according to claim 3, characterized in that: The first chromatographic column and the second chromatographic column are respectively connected to corresponding channels of the first valve. When the first valve is in an open state, the first chromatographic column and the second chromatographic column are in a conductive state; when the first valve is in a closed state, the first chromatographic column and the second chromatographic column are in a non-conductive state. At this time, the first chromatographic column performs backflushing, and the second chromatographic column separates carbon dioxide from carbon monoxide, oxygen, and carrier gas.

5. The process control and detection device for producing maleic anhydride by butane oxidation according to claim 4, characterized in that: The third chromatographic column is connected to the corresponding channel of the second valve. When the second valve is in the open state, the third chromatographic column is in the isolated state, and the separated carbon dioxide from the second chromatographic column is detected; when the second valve is in the closed state, the carbon monoxide, oxygen, and carrier gas in the third chromatographic column are detected.

6. The process control and detection device for producing maleic anhydride by butane oxidation according to claim 4, characterized in that: The fourth chromatographic column and the fifth chromatographic column are respectively connected to corresponding channels of the fourth valve. When the fourth valve is in an open state, hydrocarbon compounds are separated in sequence on the fourth chromatographic column and the fifth chromatographic column.

7. The process control and detection device for producing maleic anhydride by butane oxidation according to claim 1, characterized in that: The detection device is a gas chromatograph, which also includes: FID detector, which is used to analyze the separated C1-C5 hydrocarbons; The TCD detector is designed with helium as the reference gas and is used to analyze carbon monoxide, oxygen, carrier gas, and carbon dioxide separated from permanent gases.

8. A process control and detection method for producing maleic anhydride by oxidation of butane, characterized in that: The detection device according to any one of claims 1 to 7 is used to separate sample components and detect purity.

9. The process control and detection method for producing maleic anhydride by butane oxidation according to claim 8, characterized in that: The samples include: standard gas, butane raw gas sample and reaction process gas.

10. The process control and detection method for producing maleic anhydride by butane oxidation according to claim 8, characterized in that: During the separation of the sample components, the programmed temperature conditions are specifically as follows: Initial temperature 60-80℃, maintain for 0-1min; Raise the temperature to 80-100°C at a rate of 10-20°C / min and hold for 0-1min; Raise the temperature to 150-190°C at a rate of 20-30°C / min and hold for 0-5 minutes; Cool down to 60-100℃ at a rate of 30-50℃ / min and hold for 0-1min.

11. The process control and detection method for producing maleic anhydride by butane oxidation according to claim 8, characterized in that: The vaporization temperature in the detection method is 100-150°C; the detection temperature is 200-280°C.

12. The process control and detection method for producing maleic anhydride by butane oxidation according to claim 8, characterized in that: The split ratio in the detection method is 20:1-150:

1.

13. The process control and detection method for producing maleic anhydride by butane oxidation according to claim 8, characterized in that: The sample injection volume is controlled by a quantitative loop, and the injection volume is 1-5 mL; the detection and analysis time is 7-10 min.

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