A mineral material composite cobalt-based catalyst, a preparation method and application thereof

Abstract

The present application relates to a kind of mineral material composite cobalt-based catalyst, preparation method and its application.The mineral material composite cobalt-based catalyst includes mineral material and cobalt, mineral material is selected from one or more than two combinations of malachite, monazite, manganese ore, mullite, attapulgite, copper ore, iron ore and ilmenite, and the content of cobalt is 25~75% by mass of element, the valence of cobalt is mainly metal oxide, the ratio of Co 3+ / Co 2+ In metal oxide is 0.2~0.8.The mineral material composite cobalt-based catalyst of the present application is simple in preparation method, low in cost, can effectively catalyze oxidation of low-carbon alkane organic volatile matter, and still can maintain higher low-carbon alkane conversion rate under water vapor condition.

Description

Technical Field

[0001] This invention relates to a mineral-based composite cobalt-based catalyst. More specifically, this invention relates to a method for preparing the mineral-based composite cobalt-based catalyst. This invention also relates to the application of the catalyst in the catalytic treatment of volatile organic compounds, particularly in the catalytic oxidation of volatile organic compounds containing low-carbon light hydrocarbons. Background Technology

[0002] In recent years, with the continuous development of the social economy, the country has formulated strict VOCs emission standards and encouraged the development and application of efficient and green VOCs treatment technologies. Catalytic oxidation, absorption, adsorption, condensation, biological methods, and regenerative thermal oxidation are widely used for the recovery / treatment of various waste gases containing volatile organic compounds (VOCs). Among these, refining and chemical enterprises and painting enterprises typically use catalytic oxidation, regenerative thermal oxidation, and condensation adsorption to treat VOCs-containing waste gases. However, the low-carbon light hydrocarbons (including but not limited to C2-C5 hydrocarbons) in the waste gases have small molecular weights and high stability. In cases of large volumes and high concentrations, regenerative thermal oxidation and catalytic oxidation are almost always used. The former, regenerative thermal oxidation, has a temperature above 760℃ and high energy consumption. The latter, because it uses precious metal catalysts with a content as high as 1.6g / L or more, although the reaction temperature can be reduced to 450-520℃, its cost remains high.

[0003] Mineral-based materials are an important component of the Earth's crust and are abundant in sources. In particular, minerals containing manganese, copper, iron, vanadium, and rare earth elements possess rich catalytic active sites and have been reported in numerous publications as catalysts or catalyst supports. For example, Wang Ying et al. used molybdenum oxide supported on monazite for NH3-SCR (Rare Metals & Hard Alloys, 2023, 51(01):40-46). Wu Huizhong prepared an NH3-SCR denitration catalyst using Bayan Obo rare earth ore (Inner Mongolia University of Science and Technology, 2021). Wang Jingming conducted basic research on the application of natural mineral-based catalysts in the degradation of polyethylene plastics to produce alkane and olefins (Master's thesis, Southwest University of Science and Technology, 2020). The mineral composite material supported on ruthenium single-atom catalyst prepared in Chinese patent CN116791131A exhibits high electrocatalytic activity, high product selectivity, and stability. Chinese patent CN114160131A discloses a freeze-dried modified sepiolite group mineral-supported Pd single-atom catalyst. Although sepiolite group minerals, as natural minerals, have advantages such as low price and abundant resources, the actual process involves freezing and drying steps, and Pd, as a precious metal, is easily poisoned and expensive, which greatly limits its industrial application. Yin Shoulai investigated the low-temperature NH3-SCR denitrification performance of natural manganese iron ore catalysts. The results showed that manganese ore with Mn:Fe:Al:Si = 1.51:1.26:0.34:1 achieved a denitrification conversion rate of 94% at 120℃ (Master's thesis, Anhui University of Technology, 2020). Ye et al. prepared a composite material of manganese ore and Co3O4 using the sol-gel method for the gas-phase oxidation of chlorobenzene. The results showed that when the mass ratio of manganese ore to cobalt oxide was 0.4 (the molar ratio of cobalt to manganese was 3.6, and the mass fraction of Co was 20.9%), the catalyst prepared had better chlorobenzene oxidation performance (Journal of Saudi Chemical Society, 2021, 25(5): 101229).

[0004] In summary, existing composite catalysts using natural minerals as carriers and composite noble metals are costly to prepare; natural minerals, without processing, directly interact with metal salts and are calcined to form catalysts, resulting in low catalytic efficiency. Therefore, there is an urgent need to develop a high-efficiency, low-cost mineral-material composite non-noble metal catalyst that can be easily manufactured, exhibits good catalytic oxidation performance for low-carbon light hydrocarbons in VOCs, and has excellent stability, allowing for long-term repeated use. Summary of the Invention

[0005] In view of the existing problems in the catalytic oxidation of light hydrocarbons, the inventors, through diligent research based on existing technologies, discovered that by using natural mineral materials as the original matrix and further treating them with appropriate modification methods, while introducing the non-precious metal cobalt element, a composite catalyst can be prepared. This catalyst has good catalytic oxidation performance and stability of light hydrocarbons, thus completing the present invention.

[0006] Specifically, this invention provides a mineral-based composite cobalt-based catalyst, comprising mineral materials and cobalt. The mineral materials include one or more combinations of malachite, monazite, manganese ore, mullite, attapulgite, copper ore, iron ore, and ilmenite. The cobalt content, based on elemental mass, is 25-75%, and the cobalt valence state is predominantly in the metal oxide state, with Co in the metal oxide state being... 3+ / Co 2+ The proportion is 0.2~0.8. Preferably, the cobalt content is 30~60% by mass of elemental cobalt.

[0007] In this invention, after high-temperature calcination, the metal elements and Co elements in the ore are mainly in the oxidation state. However, during the reaction process, there may be a process of coexistence of multiple valence states and mutual transformation of multiple valence states. This process maintains the activity and stability of the catalyst.

[0008] Furthermore, the specific surface area of ​​the mineral material composite cobalt-based catalyst is 10~50 m². 2 / g, pore volume 0.05~0.23cm 3 / g, with a pore size of 3.0~9.6nm. Furthermore, the specific surface area of ​​the mineral material composite cobalt-based catalyst is 20~45 m² / g. 2 / g.

[0009] This invention also provides a method for preparing the above-mentioned mineral material composite cobalt-based catalyst, comprising the following steps: An activated mineral matrix is ​​obtained by using a natural mineral as the original matrix and modifying the original matrix. The activated mineral matrix is ​​brought into full contact with a cobalt-containing compound to obtain the contact product of the activated mineral matrix and the cobalt compound; (3) The contact product is calcined to obtain the mineral material composite cobalt-based catalyst.

[0010] In this invention, after modification and contact treatments are completed, heat treatment steps such as filtration, drying, and air drying can be performed within one or two steps. This heat treatment can be carried out at 20~150℃, preferably 30~120℃, and more preferably 50~100℃.

[0011] In step (2) above, there are no particular restrictions on the contact method, as long as sufficient contact between the activated mineral matrix and cobalt can be achieved, and a uniform contact product can be formed. For example, the raw material components can be mixed (stirred if necessary) in any manner known in the art until homogeneous.

[0012] Further, in step (1), the method for modifying the original matrix is ​​to use one or more of the following as modifiers: acid, alkali or strong oxidizing agents other than acid and alkali to activate the powdered original matrix.

[0013] Further, the mass ratio of the original matrix to the modifier is 1:1 to 10, more preferably 1:3 to 7. The modification treatment temperature is 20 to 100°C, more preferably 30 to 95°C; the modification treatment time is 1 to 10 hours, more preferably 4 to 8 hours.

[0014] During the modification process, stirring can be performed, preferably at a stirring rate of 200-500 r / min. In this invention, the modification process can increase the specific surface area of ​​the mineral matrix.

[0015] Furthermore, in step (1) above, the acid, base, and strong oxidizing agent can be organic or inorganic substances, such as inorganic acids, inorganic bases, organic acids, organic bases, hydrogen peroxide, potassium permanganate, etc. These inorganic and organic substances can be used individually or in combination as needed.

[0016] The inorganic acid can be any type of inorganic acid known in the art, such as one or more combinations of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and perchloric acid.

[0017] The inorganic base can be an alkali metal hydroxide or an alkaline earth metal hydroxide, such as one or more combinations of sodium hydroxide, calcium hydroxide, potassium hydroxide, magnesium hydroxide, and lithium hydroxide.

[0018] The organic acid can be any type of monocarboxylic acid and polycarboxylic acid known in the art, for example, C14-carboxylic acids having 2 to 10 (preferably 3 to 6) carboxyl groups. 2-20 Alkanes, such as oxalic acid, succinic acid, and adipic acid, are examples. The monocarboxylic acids may also include C14 groups optionally having one or more hydroxyl groups (e.g., 1 to 6) and 1 to 10 (preferably 3 to 6) carboxyl groups. 2-20 Alkanes, such as malic acid, tartaric acid, citric acid, and stearic acid, can be used. Alternatively, the polycarboxylic acids can also be C... 2-20 Polycarboxylated alkyl (poly)amines are obtained by inserting one or more nitrogen atoms into an alkane chain, such as hypozinotriacetic acid and ethylenediaminetetraacetic acid.

[0019] The organic base can be any type of polyamine and nitrogen-containing basic organic compound known in the art, such as urea, pyridine, ephedrine, ethylenediamine, diethylenetriamine, triethylenetetramine, dopamine, etc.

[0020] Further, in step (2), the cobalt compound is a soluble salt of cobalt. More preferably, it is a chloride salt, nitrate salt, acetate salt, sulfate salt, etc., but not limited thereto.

[0021] Further, in step (2), after mixing the activated mineral matrix with the cobalt compound, a dispersant is added to ensure that the activated mineral matrix and the cobalt compound are in full contact to form a gel-like contact product. Further, the ratio of the total mass of the activated mineral matrix and cobalt to the mass of the dispersant is 100:(1~30), and the temperature at which the gel is formed is 0~150℃.

[0022] To ensure more uniform and sufficient contact, or to facilitate contact, step (2) is carried out in the presence of a dispersion medium such as water, in which case the resulting contact product may be in the form of a slurry or paste-like liquid.

[0023] In this invention, step (2) can be performed at any temperature from 0°C to 150°C, for example, at room temperature. When the temperature is higher than the boiling point of the dispersion medium, it can be performed in a pressure vessel so that the boiling point corresponding to that pressure is higher than the temperature. For convenience, room temperature is preferred, but it is not always the case. The contact time is determined by obtaining the desired contact product, and is generally 0.5 to 5 hours, but is not always the case.

[0024] According to the present invention, the contact product, after preparation, especially when the contact product contains a slurry, may sometimes be dried by any means known in the art, such as baking, air drying, or desiccation at 50-180°C, preferably 60-150°C, and more preferably 70-120°C, to remove any dispersion medium (such as water) that may have been introduced during its preparation. According to the present invention, the dried contact product is also simply referred to as the contact product.

[0025] Furthermore, the dispersant is one or more of the following: water, inorganic acid, organic acid, monohydric alcohol, polyhydric alcohol, ether, organic base, cellulose derivatives and carboxylates.

[0026] These dispersants can be used alone or in combination as needed. The amount of dispersant is not particularly limited and can be adjusted according to the total amount of the activated mineral matrix and cobalt. Preferably, the amount of dispersant is 1 to 30 parts by mass relative to 100 parts by mass of the total amount of the activated mineral matrix and cobalt, more preferably 1.2 to 16 parts by mass, and more preferably 1.5 to 12 parts by mass.

[0027] In step (2) above, the inorganic acid can be any type of inorganic acid known in the art, such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, perchloric acid, or a combination of two or more of them.

[0028] The organic acid can be any type of monocarboxylic acid and polycarboxylic acid known in the art, for example, C14-carboxylic acids having 2 to 10 (preferably 3 to 6) carboxyl groups. 2-20 Alkanes, such as oxalic acid, succinic acid, and adipic acid, are examples. The monocarboxylic acids may also include C14 groups optionally having one or more hydroxyl groups (e.g., 1 to 6) and 1 to 10 (preferably 3 to 6) carboxyl groups. 2-20 Alkanes, such as malic acid, tartaric acid, citric acid, and stearic acid, can be used. Alternatively, the polycarboxylic acids can also be C... 2-20 Polycarboxylated alkyl (poly)amines are obtained by inserting one or more nitrogen atoms into an alkane chain, such as hypozinotriacetic acid and ethylenediaminetetraacetic acid.

[0029] The organic base can be any type of polyamine and nitrogen-containing basic organic compound known in the art, such as urea, pyridine, ephedrine, ethylenediamine, diethylenetriamine, triethylenetetramine, dopamine, etc.

[0030] The monohydric alcohol can be any type of monohydric alcohol known in the art, such as C16 alcohols with one hydroxyl group. 1-20 Alkanes, for example, include methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol.

[0031] The polyol can be any type of polyol known in the art, such as C-type polyols with 2 to 10 (preferably 3 to 6) hydroxyl groups. 2-20 Alkanes, such as ethylene glycol, diethylene glycol, propylene glycol, glycerol, pentaerythritol, or polymers of such polyols, such as polyethylene glycol, polyvinyl alcohol, etc., or may also be those mentioned in C 2-20 Polyhydroxyalkyl (poly)amines are obtained by inserting one or more nitrogen atoms into an alkane chain, such as monoethanolamine and triethanolamine.

[0032] The ether can be of the molecular formula RO(CH2CH2O). n Fatty alcohol polyoxyethylene ethers with H (R being a C3-C9 alkyl group and n being an integer from 1 to 12); molecular formula RC6H4O(CH2CH2O). n Alkylphenol polyoxyethylene ethers with the molecular formula C8H (where R is an alkyl group from C3 to C9 and n is an integer from 1 to 12). 17 (CH2CH2O) n Sec-octanol polyoxyethylene ether (H, where n is an integer from 1 to 12).

[0033] The cellulose derivatives mentioned can be those known in the art, such as methylcellulose, hydroxymethylcellulose, hydroxymethylpropylcellulose, carboxymethylcellulose, etc.

[0034] The carboxylate can be any carboxylate known in the art, such as magnesium stearate, sodium stearate, etc.

[0035] Further, in step (3), the calcination temperature is 200~580℃, preferably 200~550℃, and more preferably 250~550℃. Calcination can be carried out in an air atmosphere or in an inert gas atmosphere. The calcination time is not particularly limited and can be 1~20 hours, preferably 2~15 hours.

[0036] The present invention also provides the application of the above-mentioned mineral material composite cobalt-based catalyst in the catalytic oxidation treatment of volatile organic compounds containing low-carbon hydrocarbons.

[0037] Furthermore, the application method is as follows: a mineral-based composite cobalt-based catalyst is packed into a reactor, and a gas containing volatile organic compounds is introduced, controlling the gas hourly space velocity to be 4000~25000 h⁻¹. -1 Catalytic oxidation reaction at 150~550℃.

[0038] The beneficial effects of this invention are: the preparation method of the mineral material composite cobalt-based catalyst of this invention is simple and low in cost, and it can be used at 320℃ and a space velocity of 10000h. -1 The concentrations of ethane and propane are 500 mg / m³. 3 Under the conditions of achieving T for the catalytic oxidation conversion of ethane 90 above.

[0039] The mineral-based composite catalyst of this invention can efficiently and stably achieve the catalytic oxidation of ethane and propane. Furthermore, through long-term and cyclic evaluation, the catalyst exhibits good stability and cyclic stability. Evaluation of the catalyst's performance by introducing 3% water vapor revealed its excellent water resistance; after the water vapor was removed, the catalyst almost returned to its original catalytic oxidation conversion level for ethane and propane. Detailed Implementation

[0040] The embodiments of the present invention will be described in more detail below with reference to specific examples. However, those skilled in the art will understand that the specific embodiments described below are for illustrative purposes only and should not be considered as limiting the scope of protection of the present invention. Rather, the present invention is intended to cover all alternatives, modifications, and equivalents that may be included within the scope of the present invention as defined by the claims.

[0041] Unless otherwise specified, the various embodiments of the present invention can be combined in any way, and the resulting transformations, modifications, and alterations of the technical solutions are also included within the scope of the present invention and do not exceed the scope of the present invention.

[0042] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0043] It should be noted that, unless otherwise specified, in the embodiments of the present invention, "parts" refers to "parts by mass". Unless otherwise specified, the content of each metal element is calculated as elemental.

[0044] In this invention, the surface area is determined by the BET specific surface area measurement method.

[0045] The pore volume was determined using the BJH (Barrett-Joyner-Halenda) method.

[0046] The average pore size was determined using the BJH method.

[0047] The cobalt valence state in the mineral-based cobalt composite catalyst was determined by XPS (X-ray photoelectron spectroscopy). 3+ / Co 2 + The valence ratio was calculated using XPS peak fitting. Example 1

[0048] Six parts by mass of natural manganese ore powder (Mn 25%, Fe 16%, Si 15%, Al 4%) were treated with 50 parts by mass of a 3% HNO3 aqueous solution at 55℃ for 3 hours. The mixture was then filtered, washed with water until neutral, and dried at 130℃ to constant weight to obtain an activated mineral matrix. One part by mass of the activated mineral matrix was mixed with 2.5 parts by mass of cobalt nitrate hexahydrate, and 0.13 parts by mass of PEG-200 (polyethylene glycol-200) were added. A gel was formed at 80℃. The gel was calcined at 450℃ for 3 hours to obtain the mineral-based composite cobalt-based catalyst A, Co. 3+ / Co 2+ The ratio is 0.71, and the specific surface area is 43 m². 2 / g, pore volume is 0.19cm 3 / g, with a pore size of 3.9nm.

[0049] Comparative Example 1 One part by weight of natural manganese ore powder (Mn 25%, Fe 16%, Si 15%, Al 4%) was mixed with 2.5 parts by weight of cobalt nitrate hexahydrate, and 0.13 parts by weight of PEG-200 was added. A gel was formed at 80°C. The gel was calcined at 450°C for 3 hours to obtain the mineral-based composite cobalt-based catalyst Al, Co.3+ / Co 2+ The ratio is 0.45, and the specific surface area is 18m². 2 / g, pore volume 0.07cm 3 / g, with a pore size of 10.6nm. Example 2

[0050] Six parts by mass of natural manganese ore powder (Mn 25%, Fe 16%, Si 15%, Al 4%) were treated with 50 parts by mass of a 3% perchloric acid aqueous solution at 55°C for 3 hours. The mixture was then filtered, washed with water until neutral, and dried at 130°C to constant weight to obtain the activated mineral matrix. One part by mass of the activated mineral matrix was mixed with three parts by mass of cobalt acetate, and 0.34 parts by mass of ethylene glycol were added. A gel was formed at 80°C. The gel was calcined at 470°C for 3 hours to obtain the mineral-based composite cobalt-based catalyst B, Co. 3+ / Co 2+ The ratio is 0.69, and the specific surface area is 45m². 2 / g, pore volume is 0.19cm 3 / g, with a pore size of 4.0nm. Example 3

[0051] Six parts by mass of natural manganese ore powder (Mn 25%, Fe 16%, Si 15%, Al 4%) were treated with 50 parts by mass of a 3% HNO3 aqueous solution at 55°C for 3 hours. The mixture was then filtered, washed with water until neutral, and dried at 130°C to constant weight to obtain an activated mineral matrix. One part by mass of the activated mineral matrix was mixed with 3.5 parts by mass of cobalt nitrate hexahydrate, and 0.31 parts by mass of ethylene glycol were added. A gel was formed at 90°C. The gel was calcined at 480°C for 4 hours to obtain the mineral-based composite cobalt-based catalyst C, Co. 3+ / Co 2+ The ratio is 0.77, and the specific surface area is 38 m². 2 / g, pore volume is 0.13cm 3 / g, with a pore size of 4.1nm. Example 4

[0052] Six parts by mass of chalcopyrite powder (Cu 37%, Fe 26%, Si 6%, Al 5%, Mn 3%) were treated with 50 parts by mass of a 3% sulfuric acid aqueous solution at 80℃ for 3 hours. The mixture was then filtered, washed with water until neutral, and dried at 130℃ to constant weight to obtain an activated mineral matrix. One part by mass of the activated mineral matrix was mixed with 2.9 parts by mass of cobalt nitrate hexahydrate, and 0.47 parts by mass of citric acid and 0.06 parts by mass of urea were added. A gel was formed at 90℃. The gel was calcined at 450℃ for 4 hours to obtain the mineral-based composite cobalt-based catalyst D,Co. 3+ / Co 2+ The ratio is 0.69, and the specific surface area is 34 m².2 / g, pore volume 0.14cm 3 / g, with a pore size of 4.6nm. Example 5

[0053] Six parts by mass of malachite (Cu 51%, Zn 9%, Fe 4%, Al 1%) were treated with 50 parts by mass of a 5% hydrochloric acid aqueous solution at 80℃ for 3 hours. The solution was then filtered, washed with water until neutral, and dried at 130℃ to constant weight to obtain the activated mineral matrix. One part by mass of the activated mineral matrix was mixed with 2.2 parts by mass of cobalt nitrate hexahydrate, and 0.05 parts by mass of nitric acid and 0.41 parts by mass of urea were added. A gel was formed at 90℃. The gel was calcined at 480℃ for 4 hours to obtain the mineral-based composite cobalt-based catalyst E, Co. 3+ / Co 2+ The ratio is 0.66, and the specific surface area is 32m². 2 / g, pore volume is 0.13cm 3 / g, with a pore size of 4.3nm. Example 6

[0054] Six parts by mass of monazite (Ce 22%, La 16%, Th 13%, Fe 4%, Al 2%) were treated with 50 parts by mass of a 5% potassium permanganate aqueous solution at 80℃ for 3 hours. The mixture was then filtered, washed with water until neutral, and dried at 130℃ to constant weight to obtain an activated mineral matrix. One part by mass of the activated mineral matrix was mixed with 2.6 parts by mass of cobalt nitrate hexahydrate, and 0.05 parts by mass of nitric acid and 0.41 parts by mass of hydroxymethylpropyl cellulose were added. A gel was formed at 90℃. The gel was calcined at 490℃ for 5 hours to obtain the mineral-based composite cobalt-based catalyst F, Co. 3+ / Co 2+ The ratio is 0.78, and the specific surface area is 30m². 2 / g, pore volume is 0.11cm 3 / g, with a pore size of 5.0nm. Example 7

[0055] Six parts by mass of mullite (Si 37%, 29% Al%, Fe 1%, Mn 2%) were treated with 50 parts by mass of an 8% hydrogen peroxide aqueous solution at 80°C for 6 hours. The mixture was then filtered, washed with water until neutral, and dried at 130°C to constant weight to obtain an activated mineral matrix. One part by mass of the activated mineral matrix was mixed with 2.1 parts by mass of cobalt nitrate hexahydrate, and 0.05 parts by mass of nitric acid, 0.08 parts by mass of ethylene glycol, and 0.45 parts by mass of hydroxymethylpropyl cellulose were added. A gel was formed at 90°C. The gel was calcined at 460°C for 5 hours to obtain the mineral-based composite cobalt-based catalyst G,Co. 3+ / Co 2+ The ratio is 0.68, and the specific surface area is 46 m². 2 / g, pore volume 0.12cm 3 / g, with a pore size of 5.1nm. Example 8

[0056] Six parts by mass of attapulgite (Si 37%, 29% Al%, Mg 1%, Mn 2%) were treated with 50 parts by mass of an 8% hydrogen peroxide aqueous solution at 80℃ for 6 hours. The solution was then filtered, washed with water until neutral, and dried at 130℃ to constant weight to obtain an activated mineral matrix. One part by mass of the activated mineral matrix was mixed with 1.9 parts by mass of cobalt nitrate hexahydrate, and 0.05 parts by mass of nitric acid, 0.08 parts by mass of ethylene glycol, and 0.41 parts by mass of hydroxymethylpropyl cellulose were added. A gel was formed at 90℃. The gel was calcined at 510℃ for 5 hours to obtain the mineral-based composite cobalt-based catalyst H,Co. 3+ / Co 2+ The ratio is 0.78, and the specific surface area is 48 m². 2 / g, pore volume 0.15cm 3 / g, with a pore size of 5.6nm. Example 9

[0057] Six parts by mass of attapulgite (Si 22%, Al 4%, Mg 29%, Fe 3%) were treated with 50 parts by mass of an 8% hydrogen peroxide aqueous solution at 80℃ for 6 hours. The solution was then filtered, washed with water until neutral, and dried at 130℃ to constant weight to obtain an activated mineral matrix. One part by mass of the activated mineral matrix was mixed with 2.4 parts by mass of cobalt nitrate hexahydrate, and 0.05 parts by mass of nitric acid, 0.08 parts by mass of ethylene glycol, and 0.41 parts by mass of hydroxymethylpropyl cellulose were added. A gel was formed at 80℃. The gel was calcined at 530℃ for 5 hours to obtain the mineral material composite cobalt-based catalyst I, Co. 3+ / Co 2+ The ratio is 0.78, and the specific surface area is 43 m². 2 / g, pore volume is 0.11cm 3 / g, with a pore size of 5.8nm.

[0058] Application Example 1 The mineral-based cobalt composite catalysts from Examples 1-9 and the A1 catalyst from Comparative Example 1 were loaded into a fixed bed, and ethane and propane were introduced at concentrations of 500 mg / m³. 3 The gaseous VOCs (the rest being air) have a space velocity of 10,000 h⁻¹. -1 The reaction was carried out at 320℃ for 5 hours, and the conversion rates of ethane and propane were determined by chromatographic analysis. The concentrations of ethane and propane introduced were 500 mg / m³. 3 The VOCs gas (3% water vapor, the remainder air) was reacted at 320℃ for 5 hours, and the conversion rates of ethane and propane were measured. After stopping the steam, ethane and propane are introduced again at concentrations of 500 mg / m³. 3 The gaseous VOCs (the rest being air) have a space velocity of 10,000 h⁻¹. -1 The reaction was carried out at 320℃ for 5 hours, and the conversion rates of ethane and propane were determined by chromatographic analysis.

[0059] The conversion rates of ethane and propane before and after water was introduced, and after the water vapor was stopped, are shown in Table 1.

[0060]

[0061] As shown in Table 1, the mineral-based composite catalyst of the present invention can efficiently and stably catalyze the oxidation of ethane and propane, and exhibits good stability, cycle stability, and water resistance. In contrast, the mineral-based composite catalyst A1 prepared in Comparative Example 1, due to the untreated natural minerals directly interacting with and calcining with the metal salt to form the catalyst, suffers from reduced catalytic efficiency and stability.

[0062] Although the invention has been described in detail herein with reference to exemplary embodiments, it should be understood that the invention is not limited to the described embodiments. Other variations, modifications, and embodiments within the scope of the invention will be recognized by those skilled in the art and who have access to the teachings herein. Therefore, the invention should be broadly interpreted in accordance with the claims set forth below.

Claims

1. A mineral material composite cobalt-based catalyst, characterized in that, It includes mineral materials and cobalt. The mineral materials are selected from one or more combinations of malachite, monazite, manganese ore, mullite, attapulgite, copper ore, iron ore, and ilmenite. The cobalt content is 25-75% by mass of elemental cobalt, and the valence state of cobalt is mainly in the metal oxide state, with Co in the metal oxide state being... 3+ / Co 2+ The ratio is 0.2 to 0.

8.

2. The mineral material composite cobalt-based catalyst according to claim 1, characterized in that, Its specific surface area is 10~60m² 2 / g, pore volume 0.05~0.23cm 3 / g, with a pore size of 3.0~9.6nm.

3. The method for preparing a mineral material composite cobalt-based catalyst according to claim 1 or 2, characterized in that, Includes the following steps: (1) Using a natural mineral as the original matrix, the original matrix is ​​modified to obtain an activated mineral matrix; (2) Take the activated mineral matrix and fully contact it with the cobalt compound to obtain the contact product of the activated mineral matrix and the cobalt compound; (3) The contact product is calcined to obtain the mineral material composite cobalt-based catalyst.

4. The method for preparing a mineral material composite cobalt-based catalyst according to claim 3, characterized in that, In step (1), the method for modifying the original matrix is ​​to use one or more of the following as modifiers: acid, alkali or strong oxidizing agents other than acid and alkali to activate the powdered original matrix.

5. The method for preparing a mineral material composite cobalt-based catalyst according to claim 4, characterized in that, The mass ratio of the original matrix to the modifier is 1:1~10, the modification temperature is 20~100℃, and the modification time is 1~10h.

6. The method for preparing a mineral material composite cobalt-based catalyst according to claim 3, characterized in that, In step (2), the cobalt compound is a soluble salt of cobalt.

7. The method for preparing a mineral material composite cobalt-based catalyst according to claim 3, characterized in that, In step (2), after mixing the activated mineral matrix with the cobalt compound, a dispersant is added to ensure that the activated mineral matrix and the cobalt compound are in full contact to form a gel-like contact product.

8. The method for preparing a mineral material composite cobalt-based catalyst according to claim 7, characterized in that, The ratio of the total mass of the activated mineral matrix and cobalt to the mass of the dispersant is 100:(1~30), and the temperature at which the gel is formed is 0~150℃.

9. The method for preparing a mineral material composite cobalt-based catalyst according to claim 7, characterized in that, The dispersant is one or more of the following: water, inorganic acid, organic acid, monohydric alcohol, polyhydric alcohol, ether, organic base, cellulose derivatives and carboxylates.

10. The method for preparing a mineral material composite cobalt-based catalyst according to claim 3, characterized in that, In step (3), the roasting temperature is 200~580℃.

11. The application of the mineral material composite cobalt-based catalyst according to claim 1 in the catalytic oxidation treatment of volatile organic compounds containing low-carbon hydrocarbons.

12. The application according to claim 11, characterized in that, A mineral-based composite cobalt catalyst was packed into the reactor, and a gas containing volatile organic compounds was introduced, with the gas hourly space velocity controlled at 4000~25000 h⁻¹. -1 Catalytic oxidation reaction at 150~550℃.

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