Use of gaseous alkanes in reducing the risk of deflagration during deoxygenation of oxygen-containing gas

Abstract

The application relates to the field of mixed gas purification and discloses application of gaseous alkane in reducing the risk of combustion and explosion in the deoxidation process of oxygen-containing gas, which comprises: mixing the oxygen-containing gas with hydrogen in the presence of stabilizing gas to perform an oxidation reaction; wherein the stabilizing gas is gaseous alkane, and the oxygen-containing gas contains oxygen and optional other flammable gas. The method for deoxidizing the oxygen-containing light hydrocarbon by hydrogen provided by the application reduces the risk of combustion and explosion of the mixed gas by taking gaseous alkane as the stabilizing gas, adopts the hydrogen-catalyzed reaction to promote the reaction of oxygen in the mixed gas with hydrogen to generate water, achieves the purpose of deoxidation of the oxygen-containing gas, the reaction product is clean, the hydrogen-catalyzed reaction can effectively inhibit the occurrence of carbon deposition on the surface of the catalyst and the generation of carbon oxides, and the hydrogen-catalyzed reaction has strong bearing capacity for the fluctuation of the oxygen content of the raw material gas.

Description

Technical Field

[0001] This invention relates to the field of mixed gas purification, specifically to the application of gaseous alkanes in reducing the risk of combustion and explosion during the deoxygenation of oxygen-containing gases. Background Technology

[0002] In many oil refining and chemical production processes, the presence of oxygen can easily cause various adverse effects, such as catalyst poisoning, product quality degradation, and safety accidents. For example, in reactions using metallic Ni catalysts, the introduction of oxygen can lead to catalyst deactivation due to oxidation; in olefin polymerization, oxygen acts as a polymerization inhibitor, affecting the polymerization reaction; and the mixing of flammable organic and inorganic gases with oxygen, accumulating to a certain concentration, may cause combustion or explosion, resulting in production safety accidents. Therefore, from both process requirements and production safety perspectives, oxygen in the mixed gases of some chemical processes needs to be controlled or removed. With the increasing demands for energy conservation, environmental protection, and safe production in the domestic and international refining and chemical industries in recent years, the demand for deoxygenation of industrial mixed gases involved in production processes has been continuously increasing, and the control of oxygen content has become increasingly stringent. SH3009-2013 "Design Specification for Flammable Gas Emission Systems in Petrochemical Industry" 5.3.1 stipulates that "flammable gases with an oxygen content greater than 2% (vol)" should not be discharged into the plant's overall flammable gas emission system, such as flares and incinerators. The development of chemical process technology has led to an expansion of the application scenarios of deoxygenation technology, which has also put forward newer and higher requirements for mixed gas deoxygenation technology.

[0003] Currently, three main deoxygenation methods are used in industrial production: chemical adsorption deoxygenation, activated carbon high-temperature deoxygenation, and catalytic deoxygenation. Chemical adsorption deoxygenation mainly utilizes deoxygenating agents (such as CN1955150A) to react chemically with oxygen, consuming the oxygen in the system to achieve deoxygenation. However, this method has the disadvantage of short adsorbent lifespan and inability to be used continuously on a large scale. Activated carbon high-temperature deoxygenation is mainly used for deoxygenation of inert gases. Under high-temperature conditions, activated carbon reacts with oxygen to remove oxygen. However, its development is limited by high investment, difficult operation, and difficulty in temperature control. Catalytic deoxygenation removes oxygen from the environment by reacting with gases such as hydrogen, carbon monoxide, and hydrocarbons under the action of a catalyst (e.g., Liu Yingjie et al., Development of Liquid Propylene Deoxygenation Catalyst, Industrial Catalysis, 2016, 24(1):61–64). This method is suitable for most mixed gas systems. Through efficient catalytic reaction, most of the oxygen can be removed, making it easy to achieve continuous production, which is beneficial to improving production efficiency and reducing production costs.

[0004] To ensure process safety, current catalytic deoxygenation technologies often use nitrogen to dilute the gas mixture before it enters the deoxygenation reactor, reducing the risk of combustion and explosion. However, the effect of nitrogen dilution in reducing the risk of combustion and explosion is very limited. Therefore, to improve the process safety of light hydrocarbon hydrocatalytic deoxygenation technology, it is necessary to develop more effective and safer treatment methods for this system. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of effectiveness and safety in the existing technology and to provide an application of gaseous alkanes in reducing the risk of combustion and explosion during the deoxygenation of oxygen-containing gases.

[0006] The inventors of this invention discovered during their research that the reason why dilution with nitrogen is difficult to effectively prevent combustion and explosion seems to be that the combustion limiting oxygen concentration (LOC) of hydrogen in nitrogen is low in the hydrocatalytic deoxygenation process. Further research revealed that using gaseous alkanes as stabilizing gases unexpectedly improved the safety of hydrocatalytic deoxygenation. Therefore, to achieve the above objective, this invention provides a method for deoxygenating oxygen-containing gas, comprising: mixing the oxygen-containing gas with hydrogen in the presence of a stabilizing gas to carry out an oxidation reaction; wherein the stabilizing gas is a gaseous alkane, and the oxygen-containing gas contains oxygen and optionally other flammable gases.

[0007] This invention also provides the application of gaseous alkanes as stabilizing gases in reducing the risk of combustion and explosion of oxygen-containing gases.

[0008] The present invention provides a method for deoxygenating oxygen-containing light hydrocarbons via hydrogenation. This method reduces the risk of combustion and explosion in the mixed gas by using gaseous alkanes as a stabilizing gas. Hydrogenation catalysis promotes the reaction of oxygen and hydrogen in the mixed gas to produce water, achieving the purpose of deoxygenating the oxygen-containing gas. The reaction products are clean, and the hydrogenation reaction effectively inhibits the formation of carbon deposits and carbon oxides on the catalyst surface, exhibiting strong tolerance to fluctuations in the oxygen content of the feed gas. The technical solution of this invention is particularly suitable for operating conditions where accidents such as excessively high tail oxygen concentration and reactor overheating may occur during equipment operation. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of a system for implementing the deoxygenation method of the present invention in a preferred embodiment of the present invention.

[0010] Explanation of reference numerals in the attached figures

[0011] V-1: Pre-separation buffer tank

[0012] C-1: Compressor

[0013] E-1, E-2, E-3, E-4: Heat exchangers

[0014] T-1: Separation Tower

[0015] D-1: Separation Tank

[0016] R-1: Deoxygenation reactor Detailed Implementation

[0017] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0018] This invention provides a method for reducing the risk of combustion and explosion during the deoxygenation process of oxygen-containing gas, characterized in that the method includes: mixing oxygen-containing gas with hydrogen in the presence of a stabilizing gas to carry out an oxidation reaction; wherein the stabilizing gas is a gaseous alkane, and the oxygen-containing gas contains oxygen and optionally other flammable gases.

[0019] According to the present invention, the stabilizing gas can be introduced from the outside. However, when the oxygen-containing gas contains gaseous alkanes, it may not be necessary to introduce gaseous alkanes from the outside as stabilizing gas, or the amount of stabilizing gas introduced from the outside can be reduced accordingly. That is, the "stabilizing gas" in the present invention may refer only to the gaseous alkanes contained in the oxygen-containing gas, or only to the gaseous alkanes introduced from the outside, or a mixture of gaseous alkanes contained in the oxygen-containing gas and gaseous alkanes introduced from the outside. In the present invention, the stabilizing gas is only gaseous alkanes. Therefore, the content of other inactive gases (i.e., gases that do not react with any of the hydrogen, oxygen, or other combustible gases in the system, such as helium, nitrogen, argon, carbon dioxide, vapor, etc.) in the oxidation reaction system is maintained at a low level, for example, less than 10% by volume, less than 5% by volume, less than 3% by volume, less than 2% by volume, less than 1% by volume, less than 0.5% by volume, less than 0.05% by volume, or lower.

[0020] According to the present invention, there is no particular requirement for the amount of stabilizing gas used. According to a preferred embodiment of the present invention, the volume ratio of the stabilizing gas to oxygen (in the oxygen-containing gas) is not less than 4, more preferably greater than 5, such as 6, 10, 12, 15, 18, 20, 22, 25, 30 or any value between the above values.

[0021] According to another preferred embodiment of the present invention, the stabilizing gas accounts for more than 60% of the total gas volume in the oxidation reaction system, such as 60%, 70%, 80%, 90%, 93%, 96%, 97%, 99%, or any value between the above values.

[0022] According to the present invention, "gaseous alkane" refers to alkane that is in a gaseous state under the operating conditions of the present invention. Preferably, the stabilizing gas is selected from C1-C4 (C1, C2, C3, C4) alkanes, including straight-chain or branched alkanes, preferably at least one of methane, ethane and propane.

[0023] According to the present invention, the oxygen-containing gas may also be a gas containing unsaturated hydrocarbons. To minimize the adverse effects of unsaturated hydrocarbons on the oxidation reaction, the method may further include: removing unsaturated hydrocarbons from the oxygen-containing gas in the presence of a stabilizing gas, and mixing the gas after unsaturated hydrocarbon removal with hydrogen for an oxidation reaction. Common methods in the prior art can be used to remove the unsaturated hydrocarbons, such as at least one of direct gas-liquid separation, pressurization, absorption, and cooling distillation. Direct gas-liquid separation refers to directly introducing the oxygen-containing gas into a container to allow the gas and liquid phases to separate naturally without applying pressure or controlling the temperature. The gas after unsaturated hydrocarbon removal mainly contains the stabilizing gas and oxygen, and may also contain nitrogen, carbon monoxide, hydrogen, etc.

[0024] According to the present invention, the oxygen content in the oxygen-containing gas can be 0.01-99.5% by volume (e.g., 1% by volume, 2% by volume, greater than 2% by volume, 2.5% by volume, 2.8% by volume, 3% by volume, 4% by volume, 5% by volume, 6% by volume, 10% by volume, 20% by volume, 30% by volume, 40% by volume, 50% by volume, 55% by volume, 60% by volume, 70% by volume, 80% by volume, 90% by volume, 93% by volume, 96% by volume, 99% by volume, or any value between the above values). The content of other flammable gases in the oxygen-containing gas can be 0.5-99.99% by volume (e.g., 0.1% by volume, 1% by volume, 10% by volume, 20% by volume, 30% by volume, 40% by volume, 50% by volume, 60% by volume, 70% by volume, 80% by volume, 90% by volume, 93% by volume, 96% by volume, 99% by volume, or any value between the above values).

[0025] In this invention, the oxygen-containing gas may also contain organic gases other than oxygen, such as methanol, and inorganic gases, such as argon, helium, hydrogen, nitrogen, and carbon monoxide. Therefore, the other flammable gases are flammable gases other than hydrogen and gaseous alkanes, and can be selected from various common flammable organic gases and / or flammable inorganic gases different from gaseous alkanes and hydrogen, including light hydrocarbons below C4, halogenated hydrocarbons below C4, alcohols below C4, ketones below C4, ethers below C4, and carbon monoxide.

[0026] According to a preferred embodiment of the present invention, the other flammable gas is selected from at least one of ethylene, ethylene oxide, propylene, propylene oxide, 1-butene, 2-butene, isobutene, 1,3-butadiene, acetylene, propyne, 1-butyne, 2-butyne, vinyl chloride, 3-chloropropene, 1-chloropropane, 2-chloropropane, and epichlorohydrin.

[0027] According to the present invention, the oxidation reaction refers to the reaction of hydrogen with oxygen to form water. In this reaction, there is no particular requirement for the amount of hydrogen, as long as it can react as much oxygen in the oxygen-containing gas with hydrogen to form water. Preferably, the amount of hydrogen is such that the molar ratio of hydrogen to oxygen (in the oxygen-containing gas) is 0.5 - 5, more preferably 1 - 3.

[0028] According to the present invention, the mixing (oxidation reaction) is carried out in the presence of a catalyst. The catalyst of the present invention is not specific to a certain catalyst, as long as it has the function of catalyzing the reaction of oxygen with hydrogen to form water within a suitable temperature range, so as to achieve the purpose of removing oxygen. The catalyst is selected from at least one of noble metal catalysts (such as platinum-based catalysts and / or palladium-based catalysts) and non-noble metal catalysts (such as molybdenum-based catalysts, copper-based catalysts, nickel-based catalysts, manganese-based catalysts, etc.). The active components of the catalyst can be one or more of Pt, Pd, Ru, Rh, Ir, Ag, Fe, Ni, Mn, Cu, Ce, alkali metals, and alkaline earth metals. Calculated by the metal element, the loading amount of the active component can be 0.01 - 95 g / 100 g of the carrier. The carrier of the catalyst can be one or more of alumina, silica-alumina molecular sieve, all-silica molecular sieve, aluminophosphate molecular sieve, kaolin, diatomaceous earth, and montmorillonite. The shape of the catalyst can be any one of spherical, tooth-shaped spherical, Raschig ring, cylindrical, clover-shaped, or four-leaf clover-shaped.

[0029] According to a preferred embodiment of the present invention, in order to further improve the deoxygenation effect, reduce the hydrogenation selectivity of hydrocarbon substances, and extend the service life of the catalyst, the catalyst includes a carrier and an active component and an active promoter supported on the carrier. The active component includes noble metals, and the active promoter includes alkali metals and / or alkaline earth metals. The catalyst satisfies the following formula I and formula II:

[0030] 0.8 < D1 / (D1 + D2 + D3) < 0.98 Formula I

[0031] 5.2D1 + 2.5D2 + 160D3 < W1 / W2 < 100 Formula II

[0032] Where:

[0033] D1 represents the percentage of the pore volume occupied by pores with a pore diameter less than 20 nm in the total pore volume;

[0034] D2 represents the percentage of the total pore volume occupied by pores with a diameter of 20-50 nm.

[0035] D3 represents the percentage of the total pore volume occupied by pores with a diameter greater than 50 nm.

[0036] W1 represents the weight content of the active additive in the catalyst;

[0037] W2 represents the weight content of the active component in the catalyst.

[0038] According to the present invention, in order to further improve the oxygen removal rate, preferably, D1 is 82-96% (e.g., 82%, 84%, 86%, 88%, 89%, 91%, 93%, 96% or any value between the above values). Preferably, D2 is 0-20% (e.g., 1%, 2%, 4%, 4.6%, 8%, 8.5%, 9%, 11%, 12%, 15%, 17%, 18%, 19%, 20% or any value between the above values). Preferably, D3 is 0-5% (e.g., 0.1%, 0.15%, 0.25%, 0.4%, 0.8%, 0.9%, 1%, 1.2%, 2%, 3%, 4%, 5% or any value between the above values).

[0039] According to the present invention, in order to further improve the oxygen removal rate, preferably, W1 / W2 = 6-100, more preferably W1 / W2 = 10-75 (such as 10, 12, 15, 20, 25, 30, 32, 38, 40, 50, 60, 68, 70, 72, 75 or any value between the above values).

[0040] According to the present invention, there are no particular requirements for the content of the support, active component, and active additive. Preferably, based on the total amount of catalyst, the content of the active component, calculated as metal element, is 0.01-5% by weight, more preferably 0.1-1% by weight.

[0041] Preferably, the content of active additives, calculated as metal elements, is 0.1-20% by weight, more preferably 5-10% by weight, based on the total amount of catalyst.

[0042] Preferably, the content of the support is 75-99.8% by weight, more preferably 85-94% by weight, based on the total amount of catalyst.

[0043] In this invention, unless otherwise stated, the total amount of catalyst = amount of active component in terms of metal element + amount of active additive in terms of metal element + amount of support.

[0044] According to the present invention, preferably, the weight ratio of active additive to active component, based on metal element, is 6-100:1.

[0045] According to the present invention, preferably, the active agent is an alkali metal and an alkaline earth metal, wherein the weight ratio of the alkali metal to the alkaline earth metal is 5-10:1, more preferably, the weight ratio of the alkali metal to the alkaline earth metal is 6-9:1. The deoxidation performance of the catalyst can be further improved by combining alkali metal and alkaline earth metal. More preferably, the active agent is selected from at least one of Na, K, and Cs and at least one of Mg, Ca, and Ba; most preferably, a combination of Na and Mg, or a combination of K and Ca.

[0046] According to the present invention, the active component is selected from common noble metals in the art, preferably, the active component is selected from at least one of Pt, Pd, Ru, Rh, Ag and Ir; more preferably, the active component is selected from at least one of Pt, Pd and Ru.

[0047] According to another preferred embodiment of the present invention, the catalyst may further comprise a Group VIII transition metal of period four, more preferably Fe. The weight ratio of the Group VIII transition metal of period four to the active component is 3-50:1. Introducing a Group VIII transition metal of period four can further improve the sulfur resistance of the catalyst. In the present invention, when the catalyst contains a Group VIII transition metal of period four, W1 indicates only the weight content of alkali metals and alkaline earth metals, excluding the weight content of the Group VIII transition metal of period four.

[0048] According to the present invention, preferably, the carrier is selected from at least one of alumina (gamma-alumina), silica, titanium dioxide and carbon nanotubes.

[0049] According to the present invention, preferably, the catalyst has a specific surface area of ​​120-260 m². 2 / g. Preferably, the catalyst has a pore volume of 0.4-0.8 cm³. 3 / g. Preferably, the catalyst has an average pore size of 6-25 nm.

[0050] The present invention also provides a method for preparing the above-mentioned catalyst, the method comprising: calcining a support precursor and a modifier at 450-1000°C for a first calcination; loading an active component precursor and an active auxiliary agent precursor onto the first calcination product to obtain a catalyst precursor; and then subjecting the catalyst precursor to a second calcination; wherein the modifier is ammonium chloride and / or urea.

[0051] Preferably, the carrier precursor is selected from at least one of boehmite, silica sol, water glass, alumina sol, tetrabutyl titanate, and activated carbon.

[0052] Preferably, the first roasting time is 1-10 hours.

[0053] Preferably, the first roasting is carried out in air.

[0054] Preferably, the first calcination method is as follows: the carrier precursor and the modifier are heated to 450-1000℃ (such as 450℃, 490℃, 510℃, 550℃, 590℃, 600℃ / h or any value between the above values) at a heating rate of 200-600℃ / h (e.g., 200℃ / h, 210℃ / h, 250℃ / h, 290℃ / h, 310℃ / h, 350℃ / h, 390℃ / h, 410℃ / h, 500℃, 600℃, 610℃, 640℃, 660℃, 700℃, 800℃, 900℃, 1000℃ or any value between the above values) at this temperature for 1-10h (e.g., 1h, 2h, 3h, 4h, 5h, 6h, 8h, 10h or any value between the above values).

[0055] Preferably, the weight ratio of the carrier precursor to the modifier is 5-10:1.

[0056] In the preparation method of the present invention, in order to obtain the catalyst with active components and active additives as described above, those skilled in the art can select the active component precursor and the active additive precursor according to the types of active components and active additives, which will not be elaborated here.

[0057] Preferably, the precursor of the active component is selected from at least one of the active component's nitrate, chloride, acetate, and metal acetylacetonate.

[0058] More preferably, the active component precursor is selected from palladium chloride and / or chloroplatinic acid.

[0059] Preferably, the active ingredient precursor is selected from at least one of the active ingredient's nitrate, chloride, and acetate.

[0060] Preferably, the amounts of the active component precursor and the active promoter precursor are such that the content of the active component, calculated as metal element, in the prepared catalyst is 0.01-5% by weight, the content of the active promoter, calculated as metal element, is 0.1-20% by weight, and the content of the support is 75-99.8% by weight; more preferably, the content of the active component, calculated as metal element, is 0.1-1% by weight, the content of the active promoter, calculated as metal element, is 5-10% by weight, and the content of the support is 85-94% by weight.

[0061] Preferably, the amount of the active component precursor and the active auxiliary agent precursor is such that, in the prepared catalyst, the weight ratio of the active auxiliary agent to the active component, calculated by metal element, is 6-100, preferably 10-75.

[0062] Preferably, the amount of alkali metal precursor and alkaline earth metal precursor in the active auxiliary precursor is such that the weight ratio of alkali metal to alkaline earth metal in the prepared catalyst is 5-10:1; more preferably, the weight ratio of alkali metal to alkaline earth metal is 6-9:1.

[0063] Preferably, the temperature of the second roasting is 0-50°C lower than that of the first roasting. Preferably, the heating rate of the second roasting is 140-240°C lower than that of the first roasting. More preferably, the second roasting process includes: performing a second roasting at 300-800°C for 1-5 hours; or, first heating to 300-800°C at a rate of 60-160°C / h, and then maintaining the temperature for 1-5 hours.

[0064] Preferably, the second roasting is carried out in air.

[0065] Preferably, the method for loading the active component precursor and the active adjuvant precursor onto the support is an impregnation method; more preferably, the method includes a process of loading the active component precursor and the active adjuvant precursor onto the support:

[0066] (1) Prepare an impregnation solution containing an active component precursor and an active auxiliary agent precursor, wherein the pH value of the impregnation solution is 0.5-4 or 9-13;

[0067] (2) The carrier is immersed in the impregnation solution, and then optionally dried after immersion.

[0068] More preferably, the process of preparing the impregnation solution containing the active component precursor and the active auxiliary agent precursor includes: dissolving the active component precursor in an acidic or alkaline solution, then mixing it with the active auxiliary agent precursor, and then introducing water to adjust the pH of the system to 0.5-4 or 9-13. Preferably, the acidic solution is selected from at least one of hydrochloric acid, nitric acid, and acetic acid, and / or the alkaline solution is selected from at least one of ammonia, sodium hydroxide, and sodium carbonate.

[0069] More preferably, the immersion time is 0.5-10 hours.

[0070] According to another preferred embodiment of the present invention, the method for preparing the catalyst may further include the step of loading a fourth-period group VIII transition metal. The method for loading the fourth-period group VIII transition metal can be a conventional impregnation method, but preferably, the fourth-period group VIII transition metal, together with a modifier, is contacted with a support precursor for a first calcination. Specifically, preferably, the support precursor is impregnated with an impregnation solution containing the modifier and the fourth-period group VIII transition metal precursor, then dried and subjected to a first calcination at 450-1000°C. The fourth-period group VIII transition metal is preferably Fe. Preferably, the amount of the fourth-period transition metal precursor is such that the weight ratio of the fourth-period transition metal to the active component in the prepared catalyst is 3-50:1.

[0071] According to the present invention, there are no particular requirements for the conditions of the mixing (oxidation reaction), as long as the oxidation reaction can occur. Preferably, the conditions of the mixing (oxidation reaction) are such that the oxygen content in the gas after the reaction is below 1.5 vol%, more preferably below 0.5 vol%. According to a more preferred embodiment of the present invention, the temperature of the oxidation reaction is lower than the ignition temperature of the catalytic combustion of the stabilized gas (gaseous alkanes) to avoid the catalytic combustion reaction between the stabilized gas and oxygen. According to a more preferred embodiment of the present invention, the conditions of the oxidation reaction include: a total gas hourly space velocity (GBHV) of 2000-20000 h⁻¹. -1 The pressure is 0.1-10MPa and the temperature is 30-600℃.

[0072] According to a preferred embodiment of the present invention, the stabilizing gas is methane, and the conditions for the oxidation reaction include: a total gas hourly space velocity (GBHV) of 2000-20000 h⁻¹. -1 The pressure is 0.1-5 MPa and the temperature is 30-500℃ (more preferably 30-150℃).

[0073] According to a preferred embodiment of the present invention, the stabilizing gas is ethane, and the conditions for the oxidation reaction include: a total gas hourly space velocity (GBHV) of 2000-15000 h⁻¹. -1 The pressure is 0.1-4.5 MPa and the temperature is 30-400℃ (more preferably 30-120℃).

[0074] According to a preferred embodiment of the present invention, the stabilizing gas is propane, and the conditions for the oxidation reaction include: a total gas hourly space velocity (GBHV) of 2000-10000 h⁻¹. -1 The pressure is 0.1-4 MPa and the temperature is 30-350℃ (more preferably 30-100℃).

[0075] According to the present invention, in order to further improve the oxidation reaction efficiency, the method may further include: mixing the oxygen-containing gas and hydrogen before the oxygen-containing gas comes into contact with hydrogen, preheating the mixed gas, and then placing the preheated gas under conditions where hydrogen oxidation occurs to carry out the reaction. The preheating ensures that the gas temperature reaches the activation temperature of the catalyst used (typically 50-300°C).

[0076] According to the present invention, the gas remaining after the reaction is mainly a stabilizing gas, and direct reuse can further reduce the energy consumption of the process. Therefore, according to a preferred embodiment of the present invention, the method further includes: reusing the gas that has not undergone oxidation as a stabilizing gas. The gas that has not undergone oxidation is condensed, and its temperature can be reduced to below 45°C. It is then passed through a circulation pump to gas-liquid separation for reuse.

[0077] According to the present invention, the water generated by the oxidation reaction can be discharged to the wastewater collection system (sewage treatment system) at regular intervals.

[0078] In this invention, the oxidation reaction can be carried out in a fixed-bed reactor, which can be, for example, an adiabatic bed or a steam drum type tube reactor.

[0079] This invention also provides the application of gaseous alkanes as stabilizing gases in reducing the risk of combustion and explosion of oxygen-containing gases. The specific types or compositions of the gaseous alkanes and oxygen-containing gases are as described above and will not be repeated here.

[0080] The present invention will be described in detail below through examples. In the following examples, the analytical method for gas components is gas chromatography; the formula for calculating the oxygen conversion rate is (volume of oxygen in the oxygen-containing gas - volume of oxygen in the reaction products) / volume of oxygen in the oxygen-containing gas × 100%.

[0081] Preparation Example 1

[0082] (1) Preparation of carrier: Boehmite powder and ammonium chloride solid were mixed at a weight ratio of 5:1 and heated to 500℃ at a heating rate of 300℃ / h, and calcined at this temperature for 5h to obtain the carrier.

[0083] (2) Preparation of impregnation solution: The components in the catalyst are fed according to their stoichiometric ratio. Palladium chloride is dissolved in 0.1 mol / L dilute hydrochloric acid. After complete dissolution, sodium nitrate and magnesium nitrate are added and stirred evenly. Then water is introduced to adjust the pH value to 3 to obtain the impregnation solution.

[0084] (3) Preparation of catalyst C1: The support is placed in the impregnation liquid and impregnated for 5 hours. After impregnation, it is stirred and evaporated at 120°C and then dried in an oven at 80°C for 12 hours to obtain the catalyst precursor. Then it is calcined in air. The calcination conditions include: first heating to 500°C at 100°C / h, and then maintaining the temperature for 3 hours.

[0085] Preparation Examples 2-3

[0086] Catalysts C2 and C3 were prepared according to the method of Preparation Example 1, except that the stoichiometric ratio of each component in the catalyst was different from that in Preparation Example 1, and the preparation conditions of the catalyst were different, as shown in Table 1.

[0087] Table 1

[0088]

[0089]

[0090] Preparation Example 4

[0091] Catalyst C4 was prepared according to the method of Example 1, except that the stoichiometric ratio of each component in the catalyst was different from that in Example 1, and the process of preparing the support was different: Fe(NO3)3 and urea were dissolved in deionized water to prepare an impregnation solution, and then boehmite powder was placed in the impregnation solution and impregnated for 3 hours. The solution was stirred and evaporated at 80°C, and then calcined at 500°C for 7 hours to obtain the support.

[0092] Preparation Example 5

[0093] Catalyst C5 was prepared according to the method of Preparation Example 1, except that the amount of active additives added was such that the weight ratio of sodium nitrate to magnesium nitrate, based on metal elements, was 1:1.

[0094] Preparation Example 6

[0095] Catalyst C6 was prepared according to the method of Preparation Example 1, except that magnesium nitrate was replaced with sodium nitrate.

[0096] Preparation Example 7

[0097] Catalyst C7 was prepared according to the method of Preparation Example 1, except that sodium nitrate was replaced with magnesium nitrate.

[0098] Preparation Example 8

[0099] Catalyst C8 was prepared according to the method of Preparation Example 1, except that the amount of active additives added was such that the weight ratio of sodium nitrate to magnesium nitrate, based on metal elements, was 1:5.

[0100] Comparative Preparation Example 1

[0101] Catalyst C9 was prepared according to the method of Preparation Example 1, except that boehmite was directly calcined at 1200°C for 5 h to obtain the support.

[0102] Comparative Preparation Example 2

[0103] The catalyst C10 was prepared according to the method of Preparation Example 1, except that solid ammonium chloride was replaced with N,N-dimethylformamide.

[0104] Comparative preparation example 3

[0105] The catalyst C11 was prepared according to the method of Preparation Example 1, except that magnesium nitrate and sodium nitrate were replaced with ferric nitrate.

[0106] Test Example 1

[0107] The structural parameters of the catalysts prepared in the above preparation examples and comparative preparation examples were characterized, and the results are shown in Table 2. The elemental composition of the catalysts prepared in the above preparation examples and comparative preparation examples was characterized. The content of metal elements in the active components and the content of metal elements in the active promoters are shown in Table 2, with the balance being the support.

[0108] Specific surface area and pore size distribution testing: conducted using American Micron... The II 3020 physical adsorption instrument was used for specific surface area analysis and pore structure determination. Specific test conditions included determining surface area and pore structure using N2 adsorption at -196℃ (liquid nitrogen temperature), and pre-treating the samples under vacuum at 300℃ until the pressure was less than 10. -3 Pa was measured using a static method. Specific surface area and pore structure were calculated using the BET method based on the adsorption isotherm.

[0109] The content of each component in the catalyst was tested using the ICP-AES method.

[0110] Table 2

[0111]

[0112] Note: R represents the weight ratio of alkali metal to alkaline earth metal.

[0113] Further analysis revealed that the ratio of iron content to W2 in Preparation Example 4 and Comparative Preparation Example 3 was 3 and 50, respectively.

[0114] Test Example 2

[0115] (1) The catalysts prepared in the above preparation examples and comparative preparation examples were used for deoxygenation treatment of oxygen-containing gases. The deoxygenation treatment conditions included: a reaction temperature of 60°C, a pressure of 0.3 MPa, and a gas hourly space velocity of 5000 h⁻¹. -1The oxygen-containing gas contains oxygen and hydrocarbon gases. Methane (stabilizing gas) and hydrogen (reducing gas) are mixed with the oxygen-containing gas. After mixing, the molar ratio of hydrogen to oxygen in the gas is 2.2:1, and the volume ratio of methane to oxygen is 15. The oxygen concentration in the oxygen-containing gas and the oxygen concentration after the reaction are shown in Table 3.

[0116] (2) The catalysts prepared in the above preparation examples and comparative preparation examples were subjected to lifetime tests. The tests were conducted according to the deoxygenation treatment conditions in step (1). The lifetime of the catalyst was characterized by the time of catalyst deactivation. Catalyst deactivation is defined as the time when the oxygen conversion rate of the catalyst is lower than 80% of the initial conversion rate. At this time, the total time of deoxygenation treatment is the lifetime of the catalyst. If the time exceeds a certain period, it means that the catalyst has not been deactivated after the treatment time reaches that period, but the experiment is not continued. The results are shown in Table 3.

[0117] Table 3

[0118]

[0119] Note: The gas content values ​​or selectivity shown refer to the average values ​​detected when the system was running until the catalyst was deactivated.

[0120] As can be seen from the results in Table 3, the catalyst prepared using the preferred embodiment of the present invention has further improved deoxygenation performance, while the selectivity and service life of the catalyst are further improved.

[0121] Examples 1-3 and Comparative Examples 1-2

[0122] according to Figure 1 The steps shown are for treating exhaust gas (containing oxygen), and the specific operations are as follows:

[0123] Oxygen-containing gas is first mixed with stabilizing gas in a pre-separation buffer tank V-1, ensuring that the stabilizing gas content in the premixed gas is not less than 90%. The premixed gas is then pressurized by the first compressor C-1 and cooled by the first heat exchanger E-1 before entering the separation tower T-1. In separation tower T-1, unsaturated hydrocarbons with C2 or higher concentrations are separated from non-condensable gases (stabilizing gas and oxygen). The condensed hydrocarbons are discharged from the bottom of separation tower T-1 and sent to the light hydrocarbon recovery system. The non-condensable gas, composed of stabilizing gas and oxygen, is discharged from the top of separation tower T-1, first exchanged heat with the deoxygenation products in the second heat exchanger E-2, and then heated by steam to the deoxygenation reaction activation temperature in the third heat exchanger E-3. At the inlet of the deoxygenation reactor R-1, it is mixed with hydrogen (the amount of hydrogen used ensures a hydrogen to oxygen molar ratio of 2.2). After entering the reactor, the product comes into contact with the catalyst in the deoxygenation reactor R-1 for hydrogen-catalyzed deoxygenation. The reaction product leaves the catalyst bed and exits from the bottom of the deoxygenation reactor R-1. The product first exchanges heat with the raw material gas from the separation tower T-1 in the second heat exchanger E-2, and then exchanges heat with the low-temperature refrigerant in the fourth heat exchanger E-4 before entering the separation tank D-1. The water and a small amount of organic matter generated in the reaction are separated from the stabilizing gas and the remaining hydrogen in the separation tank D-1 and discharged from the bottom of the separation tank D-1 to be sent to the wastewater treatment system. The stabilizing gas containing a small amount of hydrogen is discharged from the top of the separation tank D-1 and recycled back to the pre-separation buffer tank V-1.

[0124] The specific operating conditions for each of the above steps are shown in Table 1. The oxygen content at each stage is detected in real time by the online oxygen content detection and control system (the results are shown in Table 1). The gas content values ​​shown in Table 1 refer to the average values ​​detected after the system has been running for 500 hours.

[0125] The catalyst preparation method described in Table 1 is as follows: 50g of Al2O3 spheres with a diameter of 2×4mm, prepared by extrusion, are impregnated with 50ml of 5% KOH solution for 50 minutes, and then dried in a drying oven at 200℃. A solution of 0.15g PdCl2 is prepared, the pH of the solution is adjusted to 3, and then poured onto the impregnated Al2O3 support. The solution is dried at 200℃ for 6 hours, calcined at 500℃ for 4 hours, reduced with H2 at 150℃ for 2 hours, and cooled to room temperature to obtain a deoxygenation catalyst with a Pd content of 0.18g / 100g Al2O3. Different deoxygenation catalysts can be obtained by adjusting the amount of PdCl2 or the type of support.

[0126] Table 1

[0127]

[0128]

[0129] The results above show that the alkane-assisted light hydrocarbon hydrogenation catalytic deoxygenation technology described in this invention has the technical characteristics of simple operation, low cost, long-term continuous deoxygenation, and high operational safety and reliability, and has a good application prospect.

[0130] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method of reducing the risk of deflagration in a deoxygenation process of an oxygen-containing gas, characterized in that, The method comprises: mixing an oxygen-containing gas with hydrogen in the presence of a stabilizing gas to perform an oxidation reaction; wherein the stabilizing gas is a gaseous alkane, and the oxygen-containing gas contains oxygen and optionally other combustible gas; The volume ratio of the stabilizing gas to oxygen is not less than 4; the stabilizing gas accounts for more than 60% of the total volume of the gas in the oxidation reaction system; and the oxidation reaction is performed in the presence of a catalyst. The content of oxygen in the oxygen-containing gas is 0.01-99.5% by volume. The temperature of the oxidation reaction is lower than the light-off temperature of catalytic combustion of the gaseous alkane.

2. The method of claim 1, wherein, The volume ratio of the stabilizing gas to oxygen is greater than 5.

3. The method of claim 1 or 2, wherein, The stabilizing gas is selected from C1-C4 alkanes.

4. The method of claim 3, wherein, The stabilizing gas is at least one of methane, ethane and propane.

5. The method of claim 1, wherein, The oxygen-containing gas further contains unsaturated hydrocarbon, and the method further comprises: removing the unsaturated hydrocarbon in the oxygen-containing gas in the presence of the stabilizing gas, and mixing the gas after removal of the unsaturated hydrocarbon with hydrogen to perform an oxidation reaction.

6. The method of any one of claims 1, 2, 4, and 5, wherein, The content of other combustible gas in the oxygen-containing gas is 0.5-99.99% by volume. The other combustible gas is at least one of ethylene, ethylene oxide, propylene, propylene oxide, 1-butene, 2-butene, isobutylene, 1,3-butadiene, acetylene, propyne, 1-butyne, 2-butyne, vinyl chloride, 3-chloropropene, 1-chloropropane, 2-chloropropane and epichlorohydrin.

7. The method of any one of claims 1, 2, 4, and 5, wherein, The amount of hydrogen is such that the molar ratio of hydrogen to oxygen is 0.5-5.

8. The method of claim 7, wherein, The amount of hydrogen is such that the molar ratio of hydrogen to oxygen is 1-3.

9. The method of claim 1, wherein, The catalyst comprises a carrier, an active component and an active adjuvant supported on the carrier, the active component comprises a noble metal, and the active adjuvant comprises an alkali metal and / or an alkaline earth metal, and the catalyst satisfies the following formula I and formula II: 0.8 < D1 / (D1+D2+D3) < 0.98 Formula I 5.2D1+2.5D2+160D3 < W1 / W2 < 100 Formula II Wherein: D1 represents the percentage of the pore volume of pores with a pore diameter less than 20 nm to the total pore volume; D2 represents the percentage of the pore volume of pores with a pore diameter of 20-50 nm to the total pore volume; D3 represents the percentage of the pore volume of pores with a pore diameter greater than 50 nm to the total pore volume; W1 represents the weight content of the active adjuvant in the catalyst; W2 represents the weight content of the active component in the catalyst.

10. The method of claim 1, wherein, The conditions of the oxidation reaction are such that the oxygen content in the gas after the reaction is below 1.5% by volume.

11. The method of claim 10, wherein, The conditions of the oxidation reaction are such that the oxygen content in the gas after the reaction is below 0.5% by volume.

12. The method of claim 1, wherein, The stabilizing gas is methane, and the conditions of the oxidation reaction include: total volume space velocity of the gas is 2000-20000h -1 , pressure is 0.1-5MPa, and temperature is 30-500℃. Alternatively, the stabilizing gas is ethane, and the conditions of the oxidation reaction include: total volume space velocity of the gas is 2000-15000h -1 -1, pressure is 0.1-4.5MPa, and temperature is 30-400℃. Alternatively, the stabilizing gas is propane, and the conditions of the oxidation reaction include: total volume space velocity of the gas is 2000-10000h -1 , pressure is 0.1-4MPa, and temperature is 30-350℃.

13. The method of any one of claims 1, 2, 4, 5, and 8-12, wherein, The method further comprises: recycling the gas that has not undergone the oxidation reaction as the stabilizing gas.

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