A chlorinated aromatic hydrocarbon chlorination inhibitor and its preparation method and application

Abstract

The present invention discloses an inhibitor for the chlorination of chlorinated aromatic hydrocarbons, comprising the following components: one or both of copper oxide and ferric oxide, and activated carbon. The present invention also discloses a method for preparing the inhibitor, comprising: dissolving CuO and Fe2O3 in a hydrochloric acid solution, thoroughly mixing the two suspensions after ultrasonic vibration, adding activated carbon, and drying and calcining the mixture. The present invention also provides applications of the inhibitor. The present invention features mild preparation conditions, convenient operation, environmental friendliness, a simple process, high inhibition efficiency, and promising application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of chlorination generation inhibitors, and in particular to a chlorination generation inhibitor for chlorinated aromatic hydrocarbons, a preparation method thereof and an application thereof. Background Art

[0002] Persistent organic pollutants (POPs) are a class of organic pollutants that are highly toxic, semi-volatile, environmentally persistent, and bioaccumulative. They can migrate over long distances through various environmental media, posing serious risks to human health and the environment. Studies have shown that POPs are rarely formed naturally, and unintentional generation during waste incineration is the primary source of POPs in the environment. Chlorinated aromatic hydrocarbons (CAHs) are a class of compounds formed when one or more hydrogen atoms in an aromatic hydrocarbon molecule are replaced by chlorine atoms. They are typical representatives of POPs and include polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) (also known as dioxins), polychlorinated biphenyls (PCBs), and polychlorinated naphthalenes (PCNs). Among them, dioxin is known as the "poison of the century" and is 100 times more potent than arsenic. With the promotion of waste incineration technology, the emission of chlorinated aromatic hydrocarbons will further increase. The Chinese government is also paying more and more attention to the control of chlorinated aromatic hydrocarbon emissions during waste incineration. In 2014, the new waste incineration standard "Standard for Pollution Control of Municipal Waste Incineration" (GB 18485-2014) raised the dioxin control standard from 1.0ng-TEQ / Nm 3 Increased to 0.1ng-TEQ / Nm 3 The implementation of the new standard will be a huge challenge for my country's waste incineration industry. Although the control standards for flue gas emissions do not make relevant provisions for other chlorinated aromatic compounds, due to the similarity of their structure and generation mechanism, other chlorinated aromatic compounds will also be generated along with dioxins. As a signatory to the Stockholm Convention, my country is vigorously promoting relevant departments to adopt best available techniques and best environmental practices (BAT / BEP). Therefore, it is urgent to develop feasible technologies that meet the characteristics of my country's waste emissions and to efficiently and stably remove chlorinated aromatic compounds from waste incineration.

[0003] Chlorinated aromatic compounds such as dioxins produced during the incineration process are mainly generated through de novo and precursor mechanisms. Regardless of the mechanism and path, the introduction of chlorine is inevitable, that is, a chlorination reaction occurs. In the waste incineration system, dioxins and other chlorinated aromatic compounds are mainly generated in the flue gas cooling section of 200-450℃, that is, they are generated by low-temperature electrophilic substitution chlorination reaction. The electrophilic substitution reaction process of aromatic compounds is the chloride ion (Cl + ) electrophilically replaces the ionic radical of the benzene ring structure, first forming a π complex, then transitioning to an intermediate σ complex, and finally removing the hydrogen ion to complete the electrophilic substitution reaction. Incineration flue gas has a complex composition, containing a large number of aromatic compounds and metal elements. The concentrations of dibenzofuran (DF) and dibenzo-p-dioxin (DD) are 2 to 4 orders of magnitude higher than those of dioxins. Studies have shown that high concentrations of DD and DF, catalyzed by metal elements in smoke, can chlorinate to form large amounts of PCDD / Fs, which is a key step in the formation of chlorinated aromatic hydrocarbons in flue gas.

[0004] Chemical inhibition technology offers the advantages of low cost and high efficiency, and is recommended as a primary control measure. This technology can reduce the production of dioxins and other chlorinated aromatic hydrocarbons at the source. Its successful application can significantly reduce investment in end-of-pipe treatment equipment, making it an economical, environmentally friendly, and promising emission reduction control strategy. Currently, three main categories of inhibitors are being studied: alkaline inhibitors, sulfur-containing compounds, and nitrogen-containing compounds. However, studies have shown that these inhibition technologies have limited effectiveness in controlling the formation of dioxins and other chlorinated aromatic hydrocarbons in real flue gas, and under certain conditions, they may even promote the production of pollutants such as dioxins. Therefore, it is necessary to develop a highly effective inhibitor to address the challenges currently faced by inhibition technologies. Summary of the Invention

[0005] An object of the present invention is to provide an inhibitor for inhibiting the chlorination of chlorinated aromatic organic pollutants. Another object of the present invention is to provide a method for preparing the inhibitor. The synthesized inhibitor of the present invention can be placed in an environment containing incineration flue gas or a hot environment containing a large amount of aromatic compounds to inhibit the chlorination of chlorinated aromatic compounds.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A chlorinated aromatic hydrocarbon inhibitor is provided. The inhibitor is a CuO (Fe2O3)-activated carbon composite, wherein the metal oxide accounts for 0.05% to 5.0% based on the mass of the activated carbon, and more preferably accounts for 0.5% to 3.0%.

[0008] Furthermore, the CuO(Fe2O3)-activated carbon composite inhibitor is any one of a CuO-activated carbon composite, a Fe2O3-activated carbon composite or a CuO-Fe2O3-activated carbon composite.

[0009] The present invention also provides a method for preparing the above inhibitor, comprising the following specific steps:

[0010] (1) Adding activated carbon to deionized water and boiling for 1 to 2 hours, separating the solid and the liquid, and vacuum drying the solid to obtain pretreated activated carbon;

[0011] (2) adding copper oxide and iron oxide to a certain concentration of hydrochloric acid, respectively, and ultrasonically treating for 10 to 60 minutes to obtain a single oxide solution, and mixing the two single oxide solutions to obtain a mixed solution;

[0012] (3) The pretreated activated carbon is uniformly mixed with the above-mentioned mixed solution or any single oxide solution, and after standing for 8 to 12 hours, the obtained mixture is dried at 90 to 120° C., calcined, and fully ground into a uniform powder; the ground mixture is washed with deionized water several times until there is no chloride, filtered, and dried.

[0013] Furthermore, in step (1), the solid is vacuum dried at 90-120° C. for 5-10 hours.

[0014] Furthermore, in step (3), the calcination is carried out at 200-300° C. for 2-3 hours.

[0015] Furthermore, the hydrochloric acid concentration X is 0.01 to 3.0 mol / L, the copper oxide addition concentration Y≥X, and the iron oxide addition concentration Z≥1 / 3X, wherein Y+Z≤2X.

[0016] The present invention also provides a use of the above inhibitor in inhibiting the chlorination of chlorinated aromatic hydrocarbons in flue gas discharged during industrial thermal processes.

[0017] Furthermore, the amount of CuO (Fe2O3) - activated carbon composite used is more than fifty times the mass of the chlorinated aromatic hydrocarbons. The inhibitor is added continuously or sprayed into an environment containing chlorinated aromatic hydrocarbons, or the inhibitor is fixed on the bed through which the flue gas passes, thereby inhibiting the chlorination formation of chlorinated aromatic hydrocarbons. The operating temperature is lower than 300 ° C, and the more preferred operating temperature is lower than 250 ° C.

[0018] Furthermore, chlorinated aromatic hydrocarbon substances include one or both of chlorine-substituted aromatic ring compounds and chlorine-substituted aromatic ring compounds containing heteroatoms, chlorine-substituted aromatic ring compounds include mono-hexachlorobenzene, polychlorinated biphenyls, polychlorinated naphthalenes, and chlorobenzenes, and chlorine-substituted aromatic ring compounds containing heteroatoms include dioxins.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The preparation method of CuO(Fe2O3)-activated carbon inhibitor is simple, environmentally friendly and suitable for mass production.

[0021] 2. Use CuO (Fe2O3)-activated carbon inhibitor to inhibit the chlorination formation of chlorinated aromatic compounds. This process is simple to operate, has high inhibition efficiency and low energy consumption.

[0022] 3. CuO (Fe2O3)-activated carbon inhibitor controls the formation of chlorinated aromatic hydrocarbons from the source and reduces the environmental release of chlorinated aromatic hydrocarbons. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is the XRD pattern of the CuO (0.1%)-Fe2O3 (1.3%)-activated carbon composite prepared in Preparation Example 1. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments. The methods described are conventional methods unless otherwise specified, and the raw materials described can be obtained from public commercial channels unless otherwise specified.

[0026] The inhibition generation efficiency described in the following examples is calculated according to the following formula:

[0027] R=(S0-S) / S0*100%

[0028] R: Inhibition generation efficiency

[0029] S0: Concentration of chlorinated aromatic hydrocarbons when no inhibitor is added

[0030] S: Concentration of chlorinated aromatic hydrocarbons generated when inhibitor is added

[0031] Preparation Example 1

[0032] Add activated carbon to deionized water and boil for 1.5 hours, separate the solid and liquid, and vacuum dry the solid to obtain pretreated activated carbon; add 0.028g copper oxide and 0.257g iron oxide to 0.36mL and 4.83mL 1.0mol / L hydrochloric acid, respectively, wherein the concentration of copper oxide is 1.0mol / L and the concentration of iron oxide is 0.33mol / L, and mix the two after ultrasonic treatment for 15 minutes; add 10g pretreated activated carbon to the above mixture and mix well. After standing for 8 hours, the obtained mixture is dried at 105°C, calcined at 200°C for 2 hours, and then fully ground. The ground mixture is washed with deionized water several times until there is no chloride, filtered, and dried to obtain a CuO (0.1%)-Fe2O3 (1.3%)-activated carbon composite. The XRD spectrum of the obtained sample is shown as follows Figure 1 As shown in .

[0033] like Figure 1 As shown in the XRD diffraction pattern of the CuO (0.1%) -Fe2O3 (1.3%) - activated carbon composite prepared in the above Preparation Example 1, the Fe2O3 diffraction peak can be seen from the figure, but it was not detected due to the low CuO content.

[0034] Example 1

[0035] The inhibitor's effectiveness was evaluated using a fixed bed. Specifically, 0.2 g of the inhibitor obtained in Preparation Example 1 was mixed with a metal chloride and loaded onto a fixed bed as the reaction zone. The temperatures were set at 150°C, 200°C, and 250°C, respectively. 2 μL of a mixture of DD and DF was injected. The DD and DF vapors formed upon thermal evaporation were transported to the reaction zone by a carrier gas (10% O₂ + 90% N₂) at a flow rate of 6 mL / min. Following the reaction zone, the adsorption zone was filled with 0.6 g of Florisil adsorbent, maintained at a temperature below 30°C. After the reaction, the reaction medium and adsorbent were subjected to accelerated solvent extraction using toluene. The resulting extract was purified by passing it through a multilayer silica gel column and an activated alumina column. All PCDD / Fs isomers were analyzed using isotope dilution coupled with high-resolution gas chromatography / high-resolution mass spectrometry (HRGC / HRMS). The inhibition efficiency was calculated by comparing the PCDD / Fs produced by chlorination under the same conditions without the addition of the inhibitor. The inhibition efficiencies of Preparation Example 1 were found to be 99.0%, 99.9%, and 99.8% through analysis and calculation.

[0036] Example 2

[0037] A CuO (5.0%)-activated carbon composite was prepared according to Preparation Example 1, except that 1.0 g of copper oxide was added to 12.5 mL of 1.0 mol / L hydrochloric acid, where the copper oxide concentration was 1.0 mol / L. The inhibitor's effectiveness was evaluated using a fixed bed reactor, following the same procedures as in Example 1, at temperatures of 150°C, 200°C, and 250°C, respectively. Analysis and calculation revealed inhibition efficiencies of 86.2%, 84.3%, and 83.1%, respectively.

[0038] Example 3

[0039] An Fe2O3 (5.0%)-activated carbon composite was prepared according to Preparation Example 1, except that 1.0 g of iron oxide was added to 18.8 mL of 1.0 mol / L hydrochloric acid, where the iron oxide concentration was 0.33 mol / L. The inhibitor's effectiveness was evaluated using a fixed bed reactor, following the same procedures as in Example 1 at temperatures of 150°C, 200°C, and 250°C, respectively. Analysis and calculation revealed inhibition efficiencies of 75.3%, 74.3%, and 75.9%, respectively.

[0040] Example 4

[0041] A CuO (0.05%)-activated carbon composite was prepared according to Preparation Example 1, except that 0.01 g of copper oxide was added to 12.5 mL of 0.01 mol / L hydrochloric acid, resulting in a copper oxide concentration of 0.01 mol / L. The inhibitor's effectiveness was evaluated using a fixed bed reactor, following the same procedures as in Example 1 at temperatures of 150°C, 200°C, and 250°C, respectively. Analysis and calculation revealed inhibition efficiencies of 97.4%, 99.6%, and 99.8%, respectively.

[0042] Example 5

[0043] An Fe2O3 (0.05%)-activated carbon composite was prepared according to Preparation Example 1, except that 0.01 g of iron oxide was added to 18.8 mL of 0.01 mol / L hydrochloric acid, resulting in an iron oxide concentration of 0.003 mol / L. The inhibitor's effectiveness was evaluated using a fixed bed, following the same procedures as in Example 1 at temperatures of 150°C, 200°C, and 250°C, respectively. Analysis and calculation revealed inhibition efficiencies of 97.1%, 97.8%, and 98.1%, respectively.

[0044] Example 6

[0045] A CuO (0.1%)-Fe2O3 (0.4%)-activated carbon composite was prepared according to Preparation Example 1, except that 0.028 g of copper oxide and 0.080 g of iron oxide were added to 3.6 mL and 15.0 mL of 0.10 mol / L hydrochloric acid, respectively, where the concentration of copper oxide was 0.10 mol / L and the concentration of iron oxide was 0.03 mol / L. The inhibitor's effectiveness was evaluated using a fixed bed, following the same procedures as in Example 1, at temperatures of 150°C, 200°C, and 250°C, respectively. Analysis and calculation revealed inhibition efficiencies of 99.8%, 99.7%, and 99.9%, respectively.

[0046] Example 7

[0047] A CuO (1.5%)-Fe2O3 (1.5%)-activated carbon composite was prepared according to Preparation Example 1, except that 0.15 g of copper oxide and 0.15 g of iron oxide were added to 9.4 mL and 14.1 mL of 0.20 mol / L hydrochloric acid, respectively, where the concentration of copper oxide was 0.20 mol / L and the concentration of iron oxide was 0.07 mol / L. The inhibitor's inhibitory effect was evaluated using a fixed bed, following the same procedures as in Example 1, at temperatures of 150°C, 200°C, and 250°C, respectively. Analysis and calculation revealed inhibition efficiencies of 90.5%, 93.3%, and 91.9%, respectively.

[0048] Example 8

[0049] A CuO (1.5%)-Fe2O3 (1.5%)-activated carbon composite was prepared according to Preparation Example 1, except that the composite was calcined at 200°C for 3 hours. The inhibitor's effectiveness was evaluated using a fixed bed, following the same procedures as in Example 1, but at temperatures of 150°C, 200°C, and 250°C, respectively. Analysis and calculation revealed that the inhibitor's inhibition efficiencies were 95.6%, 97.8%, and 94.1%.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An application of a chlorination inhibitor for chlorinated aromatic hydrocarbons in suppressing the chlorination of chlorinated aromatic hydrocarbons in flue gas discharged during industrial heat processes, characterized in that: The inhibitor is a CuO-Fe2O3-activated carbon composite, wherein the metal oxide accounts for 0.5% based on the mass of the activated carbon; The preparation method of the inhibitor comprises the following specific steps: (1) Add activated carbon to deionized water and boil for 1 to 2 hours, separate the solid and liquid, and vacuum dry the solid to obtain pretreated activated carbon; (2) Copper oxide and iron oxide are added to a certain concentration of hydrochloric acid respectively, and ultrasonically treated for 10 to 60 minutes to obtain a single oxide solution. The two single oxide solutions are mixed to obtain a mixed solution; (3) Evenly mix the pretreated activated carbon with the above mixed solution, let it stand for 8 to 12 hours, and then heat the mixture at 90 to 120 o C, and after calcination, grind thoroughly to a uniform powder. The ground mixture is washed several times with deionized water until there is no chloride, filtered, and dried; In step (3), the calcination is carried out at 200 o C for 2 to 3 hours; The hydrochloric acid concentration X is 0.01 mol / L, the copper oxide concentration Y ≥ X, and the iron oxide concentration Z ≥ 1 / 3X, where Y + Z ≤ 2X; The dosage of the inhibitor is more than fifty times the mass of the chlorinated aromatic hydrocarbons. The inhibitor is added continuously or sprayed into the environment containing the chlorinated aromatic hydrocarbons, or the inhibitor is fixed on the bed through which the flue gas passes, which can inhibit the chlorination formation of the chlorinated aromatic hydrocarbons. The operating temperature is lower than 300 o C.

2. The use according to claim 1, characterized in that In step (1), the solid is at 90~120 o C and vacuum dry for 5 to 10 hours.

3. The use according to claim 1, characterized in that Use temperature below 250 o C.

4. The use according to claim 1, characterized in that The chlorinated aromatic hydrocarbon substances include one or both of chlorine-substituted aromatic ring compounds and chlorine-substituted aromatic ring compounds containing heteroatoms. The chlorine-substituted aromatic ring compounds include mono-hexachlorobenzene, polychlorinated biphenyls, polychlorinated naphthalenes, and chlorobenzenes. The chlorine-substituted aromatic ring compounds containing heteroatoms include dioxins.

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