A combustion-type gas deoxygenation catalyst and its preparation method

Abstract

The present application belongs to the technical field of gas deoxidization and purification, and particularly relates to a combustion type gas deoxidization catalyst and a preparation method thereof. The preparation method of the combustion type gas deoxidization catalyst comprises the following steps: (1) soaking a carbon material carrier in a nitric acid solution, after the soaking is completed, performing solid-liquid separation, and cleaning and drying the obtained solid to obtain a deoxidization catalyst precursor; (2) impregnating or spraying the deoxidization catalyst precursor obtained in step (1) with a solution containing a transition metal; and (3) drying the product obtained in step (2) and calcining to obtain the combustion type gas deoxidization catalyst. The combustion type gas deoxidization catalyst has a relatively low deoxidization reaction temperature, requires less heating heat for the reaction, and has low energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of gas deoxygenation and purification technology, specifically relating to a combustion-type gas deoxygenation catalyst and its preparation method. Background Technology

[0002] With the development of modern industry and science and technology, the requirements for gas purity are becoming increasingly stringent. Oxygen in pure gases is a very important indicator, and many process conditions require the volume fraction of oxygen in the gas to reach 1.0 × 10⁻⁶. -6 Therefore, deoxidizers are widely used in petrochemical, metallurgical, electronics, and light industry fields to remove oxygen from gases of different types and uses (protective gas, reactive gas, and carrier gas).

[0003] Taking nitrogen as an example, there are currently three main directions for nitrogen deoxygenation. One is hydrodeoxygenation using air to produce high-purity oxygen, supported by precious metals, primarily platinum and palladium. The deoxygenation principle involves the reaction of hydrogen and oxygen to produce water, thereby removing oxygen from the gas. This type of catalyst requires an additional supply of excess hydrogen during the deoxygenation process, resulting in hydrogen impurities in the deoxygenated gas, making it unsuitable for the aluminum and magnesium processing industries. Another type is combustion-based deoxygenation, which utilizes carbon materials to react with oxygen in the gas, producing CO and CO2. This type of catalyst does not introduce hydrogen impurities; however, the key research areas are how to lower the combustion reaction temperature and improve the deoxygenation capacity and depth.

[0004] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a combustion-type gas deoxygenation catalyst and its preparation method, so as to solve or improve at least one of the problems of high combustion reaction temperature, low deoxygenation capacity and low deoxygenation depth of deoxygenators in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a combustion-type gas deoxygenation catalyst, comprising the following steps: (1) immersing a carbon material support in a nitric acid solution, and after immersion, separating the solid and liquid, cleaning and drying the obtained solid to obtain a deoxygenation catalyst precursor; (2) impregnating or spraying the deoxygenation catalyst precursor obtained in step (1) with a solution containing a transition metal; (3) drying and calcining the product obtained in step (2) to obtain the combustion-type gas deoxygenation catalyst.

[0007] Preferably, the carbon material carrier includes at least one of activated carbon, activated coke, and carbon fiber.

[0008] Preferably, the solution containing the transition metal is a transition metal salt solution; the transition metal in the transition metal salt is selected from at least one of iron, copper, and zinc; and the transition metal salt is selected from at least one of nitrate, carbonate, acetate, and hydrochloride.

[0009] Preferably, the solution containing the transition metal includes water and the transition metal immersed in the water; the temperature of the water is 90-100°C, and the transition metal is copper; the immersion process also includes the step of introducing carbon dioxide gas into the water.

[0010] Preferably, in step (1), the concentration of the nitric acid solution is 5wt%-10wt%, and the soaking time in the nitric acid solution is 3-5h.

[0011] Preferably, in step (1) and / or step (3), the drying temperature is 110-120°C and the drying time is 4-6 hours.

[0012] Preferably, in step (3), the roasting temperature is 170-200℃ and the roasting time is 0.8-1.2h.

[0013] The present invention also provides a combustion-type gas deoxygenation catalyst, which adopts the following technical solution: the combustion-type gas deoxygenation catalyst is prepared by the method described above; the combustion-type gas deoxygenation catalyst includes a carbon material support and an active component; the active component is a transition metal compound.

[0014] Preferably, the content of the active component, based on oxides, is 0.1 wt% to 15 wt%.

[0015] Preferably, the content of the active component, based on oxides, is 5wt%-10wt%.

[0016] Beneficial effects:

[0017] (1) The combustion-type gas deoxygenation catalyst of the present invention has a lower deoxygenation reaction temperature, requires less heating heat for the reaction, and has low energy consumption.

[0018] (2) The combustion-type gas deoxygenation catalyst of the present invention has a low deoxygenation reaction temperature, low equipment requirements, and reduced equipment investment.

[0019] (3) The deoxygenation product of the combustion-type gas deoxygenation catalyst of the present invention is CO2, which is polar and easy to remove. Compared with the gas obtained by the hydrogenation deoxygenation reaction, it is more suitable for the production process of hydrogen.

[0020] (4) The preparation method of the combustion-type gas deoxygenation catalyst of the present invention is simple, the raw materials are readily available, the preparation cost is low, and it is suitable for large-scale industrial production. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0022] The present invention will now be described in detail with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0023] This invention addresses at least one of the problems of high combustion reaction temperature, low deoxidation capacity, and low deoxidation depth in existing deoxidizers by providing a method for preparing a combustion-type gas deoxidation catalyst. The method for preparing the combustion-type gas deoxidation catalyst according to an embodiment of this invention includes the following steps: (1) immersing a carbon material support in a nitric acid solution; after immersion, separating the solid and liquid, washing and drying the resulting solid to obtain a deoxidation catalyst precursor; (2) impregnating or spraying the deoxidation catalyst precursor obtained in step (1) with a solution containing a transition metal; (3) drying and calcining the product obtained in step (2) to obtain the combustion-type gas deoxidation catalyst.

[0024] Through steps (1)-(3), the transition metal can be fully loaded onto the carbon material support, reducing the reaction temperature between the carbon material support and oxygen molecules, thereby helping to remove oxygen while lowering the combustion reaction temperature.

[0025] In step (2), by immersing the carbon material carrier in a nitric acid solution, the pores of the carbon material carrier can be expanded, enabling it to absorb transition metal ions more fully.

[0026] In a preferred embodiment of the present invention, the carbon material carrier is further subjected to sieving and purging before step (1). Sieving and purging help ensure the uniformity and cleanliness of the raw materials. If there is powder, the powder will also absorb the transition metal, which will not only cause waste, but also affect the absorption of transition metal by the carbon particles.

[0027] In a preferred embodiment of the present invention, the carbon material carrier includes at least one of activated carbon, activated coke, and carbon fiber.

[0028] In a preferred embodiment of the present invention, the solution containing the transition metal is a transition metal salt solution; the transition metal in the transition metal salt is selected from at least one of iron, copper and zinc; the transition metal salt is selected from at least one of nitrate, carbonate, acetate and hydrochloride.

[0029] In a preferred embodiment of the present invention, the solution containing a transition metal includes water and a transition metal immersed in the water; the temperature of the water is 90-100°C (e.g., 90°C, 92°C, 94°C, 96°C, 98°C or 100°C), and the transition metal is copper; the immersion process also includes the step of introducing carbon dioxide gas into the water.

[0030] In a preferred embodiment of the present invention, in step (1), the concentration of the nitric acid solution is 5wt%-10wt% (e.g., 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, or 10wt%), and the soaking time in the nitric acid solution is 3-5 hours (e.g., 3 hours, 3.5 hours, 4 hours, 4.5 hours, or 5 hours). If the concentration of nitric acid is too high, it will damage the pores of the carbon material support; if the concentration of nitric acid is too low, it will be difficult to achieve pore expansion of the carbon material support.

[0031] In a preferred embodiment of the present invention, in step (1) and / or step (3), the drying temperature is 110-120°C (e.g., 110°C, 112°C, 114°C, 116°C, 118°C or 120°C), and the drying time is 4-6 hours (e.g., 4 hours, 4.5 hours, 5 hours, 5.5 hours or 6 hours).

[0032] In a preferred embodiment of the present invention, in step (3), the calcination temperature is 170-200℃ (e.g., 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, or 200℃), and the calcination time is 0.8-1.2h (e.g., 0.8h, 0.9h, 1.0h, 1.1h, or 1.2h). In step (3), if the calcination temperature is too low, the decomposition of the transition metal salt (e.g., copper nitrate) cannot be achieved; if the calcination temperature is too high, energy will be wasted. If the calcination time is too short, the decomposition of the transition metal salt will be incomplete; if the calcination time is too long, energy will be wasted, and production efficiency will be low.

[0033] The present invention also proposes a combustion-type gas deoxygenation catalyst. The combustion-type gas deoxygenation catalyst of the present invention is prepared by the method described above. The combustion-type gas deoxygenation catalyst includes a carbon material support and an active component, wherein the active component is a transition metal compound (e.g., a transition metal oxide).

[0034] The deoxygenation principle of the combustion-type gas deoxygenation catalyst of the present invention is to utilize the empty d orbitals or d orbital electrons of the transition metal to reduce the activation energy of the reaction, that is, to reduce the temperature at which carbon materials react with oxygen molecules. Through the combustion of carbon materials with oxygen, CO and CO2 are generated, thereby achieving the purpose of deoxygenation.

[0035] In a preferred embodiment of the combustion-type gas deoxygenation catalyst of the present invention, the content of the active component, calculated as oxide, is 0.1 wt%-15 wt% (e.g., 0.1 wt%, 0.5 wt%, 1 wt%, 3 wt%, 5 wt%, 7 wt%, 9 wt%, 11 wt%, 13 wt%, 14 wt%, 14.9 wt%, or 15 wt%). The higher the content of transition metal oxides in the combustion-type gas deoxygenation catalyst, the more significant the catalytic performance of the deoxygenation catalyst, manifested in a lower combustion temperature and a higher deoxygenation depth during deoxygenation. While a lower deoxygenation combustion temperature can reduce energy consumption, it also leads to safety risks in industrial equipment and increases the production cost of the deoxygenator. Conversely, too low a content of transition metal oxides cannot achieve the desired deoxygenation effect; therefore, the content of transition metal oxides is generally within a certain range.

[0036] In a preferred embodiment of the combustion-type gas deoxygenation catalyst of the present invention, the content of the active component, based on oxides, is 5wt%-10wt% (e.g., 5wt%, 6wt%, 8wt% or 10wt%).

[0037] The combustion-type gas deoxygenation catalyst and its preparation method of the present invention will be described in detail below through specific embodiments.

[0038] Example 1

[0039] The preparation method of the combustion-type gas deoxygenation catalyst in this embodiment includes the following steps:

[0040] (1) Weigh 20g of activated carbon and soak it in 75mL of 5% HNO3 for 5h. After 5h, pour off the solution, wash it 5 times with distilled water, then pour the wet activated carbon into a Buchner funnel, vacuum filter it, and dry the filtered activated carbon in an oven at 110℃ for 2h to obtain the deoxygenation catalyst precursor.

[0041] (2) The deoxygenation catalyst precursor was placed in an equal volume of copper nitrate solution (the copper nitrate solution was prepared as follows: 15g of copper nitrate trihydrate was weighed and dissolved in 85mL of water to prepare a 15% copper nitrate solution) and soaked for 6h.

[0042] (3) After impregnation, the obtained solid is dried in an oven at 110°C and calcined in a muffle furnace at 170°C for 1 hour to obtain the combustion-type gas deoxygenation catalyst of this embodiment.

[0043] The copper content of the combustion-type gas deoxygenation catalyst in this embodiment is about 5% (calculated as CuO).

[0044] Example 2

[0045] The preparation method of the combustion-type gas deoxygenation catalyst in this embodiment includes the following steps:

[0046] (1) Weigh 20g of activated carbon and soak it in 75mL of 10% HNO3 for 3h. After 3h, pour off the solution, wash it 3 times with distilled water, then pour the wet activated carbon into a Buchner funnel, vacuum filter it, and dry the filtered activated carbon in an oven at 110℃ for 2h to obtain the deoxygenation catalyst precursor.

[0047] (2) The deoxygenation catalyst precursor was placed in an equal volume of copper nitrate solution (the copper nitrate solution was prepared as follows: 30g of copper nitrate trihydrate was weighed and dissolved in 70mL of water to prepare a 30% copper nitrate solution) and soaked for 5h.

[0048] (3) After impregnation, the obtained solid is dried in an oven at 110°C and calcined in a muffle furnace at 170°C for 1 hour to obtain the combustion-type gas deoxygenation catalyst of this embodiment.

[0049] The copper content of the combustion-type gas deoxygenation catalyst in this embodiment is about 10% (calculated as CuO).

[0050] Example 3

[0051] The preparation method of the combustion-type gas deoxygenation catalyst in this embodiment includes the following steps:

[0052] (1) Weigh 20g of activated carbon and soak it in 75mL of 10% HNO3 for 3h. After 3h, pour off the solution, wash it 3 times with distilled water, then pour the wet activated carbon into a Buchner funnel, vacuum filter it, and dry the filtered activated carbon in an oven at 110℃ for 2h to obtain the deoxygenation catalyst precursor.

[0053] (2) Place the deoxygenation catalyst precursor in an equal volume of basic copper carbonate solution (the basic copper carbonate solution is prepared as follows: weigh 30g of basic copper carbonate, dissolve it in 70mL of water to prepare a 30% basic copper carbonate solution) and immerse it for 5h.

[0054] (3) After impregnation, the obtained solid is dried in an oven at 110°C and calcined in a muffle furnace at 220°C for 1 hour to obtain the combustion-type gas deoxygenation catalyst of this embodiment.

[0055] The copper content of the combustion-type gas deoxygenation catalyst in this embodiment is about 10% (calculated as CuO).

[0056] Example 4

[0057] (1) Weigh 20g of activated carbon and soak it in 75mL of 10% HNO3 for 3h. After 3h, pour off the solution, wash it 3 times with distilled water, then pour the wet activated carbon into a Buchner funnel, vacuum filter it, and dry the filtered activated carbon in an oven at 110℃ for 2h to obtain the deoxygenation catalyst precursor.

[0058] (2) The deoxygenation catalyst precursor was placed in a mixed solution of ferrous nitrate and copper nitrate of equal volume (the ferrous nitrate solution was prepared as follows: 10g of ferrous nitrate and 20g of copper nitrate trihydrate were weighed and dissolved in 70mL of water to prepare the mixed solution of ferrous nitrate and copper nitrate) and soaked for 5h.

[0059] (3) After impregnation, the obtained solid is dried in an oven at 110°C and calcined in a muffle furnace at 170°C for 1 hour to obtain the combustion-type gas deoxygenation catalyst of this embodiment.

[0060] The combustion-type gas deoxygenation catalyst in this embodiment contains approximately 7% copper (calculated as CuO) and approximately 3% iron (calculated as FeO).

[0061] Example 5

[0062] (1) Weigh 20g of activated carbon and soak it in 75mL of 10% HNO3 for 3h. After 3h, pour off the solution, wash it 3 times with distilled water, then pour the wet activated carbon into a Buchner funnel, vacuum filter it, and dry the filtered activated carbon in an oven at 110℃ for 2h to obtain the deoxygenation catalyst precursor.

[0063] (2) Place the deoxygenation catalyst precursor in hot water at 90-100℃, insert copper plates at the same time, and then introduce carbon dioxide gas for about 1 hour.

[0064] (3) After the reaction is complete, the obtained solid is dried in an oven at 110°C and calcined in a muffle furnace at 220°C for 1 hour to obtain the combustion-type gas deoxygenation catalyst of this embodiment.

[0065] The copper content of the combustion-type gas deoxygenation catalyst in this embodiment is about 10% (calculated as CuO).

[0066] Comparative Example 1

[0067] The only difference between this comparative example and Example 1 is that the copper content of the deoxidizer in this comparative example is 2% (calculated as CuO), while the rest are the same as in Example 1.

[0068] Comparative Example 2

[0069] The only difference between this comparative example and Example 2 is that the copper content of the deoxidizer in this comparative example is 15% (calculated as CuO), while the rest are the same as in Example 2.

[0070] Experimental Example

[0071] The deoxygenation effects of the combustion-type gas deoxygenation catalysts of Examples 1-5 and the deoxygenators of Comparative Examples 1-2 were evaluated respectively.

[0072] Test method: 1g of combustion-type gas deoxygenation catalyst was placed in the reactor, which was then heated to 250℃. Nitrogen gas with an oxygen content of approximately 0.2% was passed through at a flow rate of approximately 500mL / min. The temperature was continuously increased until the oxygen content at the reactor outlet was zero. The changes in outlet oxygen content at different temperatures were recorded. The inlet oxygen content was 2000ppm, and the outlet oxygen content was less than 10ppm. The results are shown in Tables 1-5 below.

[0073] Table 1. Deoxygenation test results of the combustion-type gas deoxygenation catalyst in Example 1

[0074] Reaction time / h 0 1 2 3 4 5 Reaction temperature / ℃ 246 298 299 298 298 298 Oxygen content at export (ppm) 49 4 Undetectable Undetectable Undetectable Undetectable

[0075] Table 2. Deoxygenation test results of the combustion-type gas deoxygenation catalyst in Example 2.

[0076] Reaction time / h 0 1 2 3 4 5 Reaction temperature / ℃ 234 269 289 280 272 283 Oxygen content at export (ppm) 16 9 Undetectable Undetectable Undetectable Undetectable

[0077] Table 3. Deoxygenation test results of the combustion-type gas deoxygenation catalyst in Example 3.

[0078] Reaction time / h 0 1 2 3 4 5 Reaction temperature / ℃ 198 241 288 298 295 285 Oxygen content at export (ppm) 162 12 3 Undetectable Undetectable Undetectable

[0079] Table 4. Deoxygenation test results of the combustion-type gas deoxygenation catalyst in Example 4.

[0080] Reaction time / h 0 1 2 3 4 5 Reaction temperature / ℃ 232 269 296 287 272 276 Oxygen content at export (ppm) 86 10 Undetectable Undetectable Undetectable Undetectable

[0081] Table 5. Deoxygenation test results of the combustion-type gas deoxygenation catalyst in Example 5.

[0082] Reaction time / h 0 1 2 3 4 5 Reaction temperature / ℃ 240 250 265 260 255 256 Oxygen content at export (ppm) 29 3 Undetectable Undetectable Undetectable Undetectable

[0083] Table 6. Deoxygenation test results of the combustion-type gas deoxygenation catalyst in Comparative Example 1.

[0084] Reaction time / h 0 1 2 3 4 5 Reaction temperature / ℃ 260 316 338 345 330 340 Oxygen content at export (ppm) 115 27 4 Undetectable Undetectable Undetectable

[0085] Table 7. Deoxygenation test results of the combustion-type gas deoxygenation catalyst in Comparative Example 2.

[0086] Reaction time / h 0 1 2 3 4 5 Reaction temperature / ℃ 225 269 297 267 278 260 Oxygen content at export (ppm) 5 1 Undetectable Undetectable Undetectable Undetectable

[0087] Experimental conclusion:

[0088] As can be seen from Tables 1 and 2, the deoxidation catalyst with a copper loading of 10% has a lower deoxidation temperature than the deoxidation catalyst with a copper loading of 5%. Considering economic applicability, the deoxidation effect of the deoxidation catalyst with a copper loading of 5%-10% is more reasonable.

[0089] Compared with Table 2, Table 3 shows that the deoxygenation catalysts prepared by different methods and with different raw materials have little difference in catalytic reaction and can all achieve good deoxygenation effect.

[0090] As shown in Table 4, adding two transition metals can also achieve a good deoxidation effect. However, considering the cost and industrial production efficiency, it is recommended to use a single transition metal element.

[0091] As can be seen from the data in Table 5, Example 5, by simultaneously impregnating the deoxidizer precursor with copper sheet and hot water, greatly improves production efficiency. Compared with other production methods such as Example 3, the combustion-type gas deoxidation catalyst prepared in Example 5 has a lower reaction temperature (the temperature at which oxygen is completely removed) and a better catalytic effect (the combustion-type gas deoxidation catalyst of Example 5 can achieve complete oxygen removal within 2 hours, while the combustion-type gas deoxidation catalyst of Example 3 can only achieve complete oxygen removal within 3 hours); moreover, the raw materials are readily available and inexpensive, making the preparation method of Example 6 more suitable for industrial production.

[0092] The copper-containing deoxidizing catalyst prepared in Comparative Example 1, when introduced with nitrogen gas containing approximately 0.2% oxygen, showed an outlet oxygen content of less than 5 ppm at a reaction temperature exceeding 340°C. This indicates that while the comparative example possesses catalytic activity, its catalytic function is weak, resulting in limited reduction in ignition temperature and minimal energy savings.

[0093] The copper-containing deoxidation catalyst produced using Comparative Example 2 had a very low catalytic temperature and better catalytic depth, but it spontaneously combusted during the drying process without isolating it from air. This indicates that the catalyst's ignition temperature is too low and its catalytic performance is too reactive, making it unsuitable for industrial production.

[0094] Of the different deoxygenation catalyst preparation methods, Example 5 is more suitable for industrial application because it is simple to operate, pollution-free, and produces no toxic or harmful gases during the calcination and decomposition process, making it harmless to humans and environmentally friendly. Conversely, Examples 1-2 and 4 produce NO2 gas during the calcination and decomposition process, which can cause chronic poisoning in humans and pollute the environment, contributing to acid rain. Furthermore, the raw materials for Examples 1-4 are chemicals with limited availability and stringent storage requirements; while Example 5 uses readily available and common raw materials with lower production and storage requirements, making it more suitable for large-scale production. Moreover, Example 5 allows for the loading of transition metals onto carbon material supports in a shorter time (shorter immersion time in solutions containing transition metals), resulting in higher efficiency in deoxygenation catalyst preparation.

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A combustion-type gas deoxidizing catalyst for oxygen removal in nitrogen, characterized by, The catalyst comprises a carbon material carrier and an active component; The active component is a transition metal oxide, the transition metal is copper, and the content of the active component is 5wt%-10wt% in terms of oxide; The preparation method of the catalyst comprises the following steps: (1) soaking the carbon material carrier in a nitric acid solution, separating the solid from the liquid after the soaking, and cleaning and drying the obtained solid to obtain a deoxidation catalyst precursor; (2) impregnating or spraying the deoxidation catalyst precursor obtained in step (1) with a solution containing a transition metal; (3) drying and calcining the product obtained in step (2) to obtain the combustion-type gas deoxidation catalyst; In step (2), the solution containing a transition metal is a transition metal salt solution, and the transition metal in the transition metal salt is copper; In step (3), the calcining temperature is 170-200℃, and the calcining time is 0.8-1.2 h.

2. The combustion-type gas deoxidizing catalyst according to claim 1, characterized by, The carbon material carrier comprises at least one of activated carbon, activated coke and carbon fiber.

3. The combustion-type gas deoxidizing catalyst according to claim 1, wherein The transition metal salt is selected from at least one of nitrate, acetate and hydrochloride.

4. The combustion-type gas deoxidizing catalyst according to claim 1, wherein In step (1), the concentration of the nitric acid solution is 5wt%-10wt%, and the soaking time in the nitric acid solution is 3-5 h.

5. The combustion-type gas deoxidizing catalyst according to claim 1, wherein In step (1) and / or step (3), the drying temperature is 110-120℃, and the drying time is 4-6 h.