Medium-temperature flue gas denitration catalyst and preparation method thereof

Abstract

The invention provides a medium-temperature flue gas denitration catalyst and a preparation method thereof. The catalyst provided by the invention can be suitable for flue gas treatment in a medium temperature zone, can still maintain high reaction activity in a wide reaction temperature zone (200-400 DEG C), and has high denitration activity. Compared with a traditional SCR catalyst, the catalyst provided by the invention not only has excellent denitration efficiency, but also has better flue gas temperature adaptability, and can keep stable denitration performance at a lower temperature. In addition, the preparation method of the catalyst is simple, raw materials are convenient and easy to obtain, the production period is short, almost no pollution is caused to the environment, and batch production can be achieved.

Description

Technical Field

[0001] The invention relates to a medium-temperature flue gas denitration catalyst and a preparation method thereof, and belongs to the field of flue gas denitration. Background Art

[0002] With the acceleration of industrialization and the increasing severity of environmental pollution, flue gas denitrification technology has become one of the key means to ensure the quality of the atmospheric environment. However, one of the current challenges is the decline in denitrification efficiency caused by flue gas temperature fluctuations. During the flue gas treatment process, as the operating conditions change, the flue gas temperature often fluctuates violently, especially in the case of load reduction and peak load period, the flue gas temperature often drops below the suitable operating temperature of the SCR catalyst, resulting in reduced denitrification efficiency.

[0003] To solve this problem, there is an urgent need for an efficient SCR catalyst that can adapt to flue gas temperature fluctuations. In particular, there is a need for a medium-temperature flue gas denitrification NH3-SCR technology that has the advantages of high efficiency, low cost, and strong adaptability, so that it can be widely used in the field of flue gas treatment. Summary of the invention

[0004] Problem that the invention aims to solve

[0005] In view of the problem of reduced denitration efficiency caused by temperature fluctuations in current flue gas treatment, the purpose of the present invention is to provide a catalyst that can achieve flue gas denitration in the medium temperature range and a preparation method thereof. The catalyst of the present invention can effectively adapt to the current situation of flue gas temperature reduction caused by flue gas peak regulation and load reduction.

[0006] Solutions for solving problems

[0007] The inventors of the present invention have conducted in-depth research to solve the above problems. As a result, they found that a catalyst with high denitration activity was obtained by using active components of metal salt, aluminum source compound and complexing agent as a matrix and using readily available raw materials through a sol-gel method. Compared with traditional SCR catalysts, the catalyst of the present invention not only performs well in denitration efficiency, but also has better flue gas temperature adaptability and can maintain stable denitration performance at lower temperatures.

[0008] That is, the present invention is as follows.

[0009] [1]. A method for preparing a medium-temperature flue gas denitration catalyst, comprising:

[0010] Step A: mixing the active component metal salt, the aluminum source compound and the complexing agent and heating and drying them to obtain a catalyst precursor; and

[0011] Step B: calcining the catalyst precursor to obtain a denitration catalyst.

[0012] [2] The preparation method according to [1], wherein the step A comprises:

[0013] Step A1: mixing the active component metal salt, the aluminum source compound and the complexing agent to obtain a mixed solution precursor; and

[0014] Step A2: heating, stirring and drying the mixed solution precursor to obtain a catalyst precursor.

[0015] [3] The preparation method according to [2], wherein the step A or step A1 satisfies at least one of the following characteristics (a) to (j):

[0016] (a) the active component in the active component metal salt includes at least one of iron, manganese, cerium, cobalt, nickel, copper, tin, lanthanum and zirconium;

[0017] (b) the active component metal salt is a soluble metal salt of the active component;

[0018] (c) the active component metal salt is at least one of a nitrate, an acetate and a chloride of the active component;

[0019] (d) the active component metal salt includes at least one of ferric nitrate, ferric acetate, ferric chloride, manganese acetate, manganese nitrate, manganese chloride, cerium nitrate, cerium chloride, cobalt nitrate, cobalt acetate, cobalt chloride, nickel nitrate, nickel acetate, nickel chloride, copper nitrate, copper acetate, copper chloride, tin tetrachloride, lanthanum nitrate and zirconium nitrate;

[0020] (e) the aluminum source compound is an aluminum salt;

[0021] (f) the aluminum source compound comprises aluminum nitrate, aluminum acetate or aluminum chloride;

[0022] (g) the complexing agent includes at least one of a substance having one or more carboxyl groups, a substance having two or more amino groups, and a substance having two or more hydroxyl groups;

[0023] (h) the complexing agent comprises citric acid or oxalic acid;

[0024] (i) the molar ratio of the active component metal salt to the aluminum source compound is 0.2:1 to 4:1;

[0025] (j) The molar ratio of the active component metal salt to the complexing agent is 0.2:1 to 1:1.

[0026] [4] The preparation method according to [2], wherein the step A or step A2 satisfies at least one of the following characteristics (k) to (n):

[0027] (k) The heating temperature is 110 to 130° C.;

[0028] (l) Heating and stirring time is 2 to 6 hours;

[0029] (m) drying temperature is 100 to 130°C;

[0030] (n) Drying time is 4 to 12 hours.

[0031] [5] The method according to any one of [1] to [4], wherein the step B satisfies at least one of the following characteristics (o) to (q):

[0032] (o) calcination temperature is 400 to 600°C;

[0033] (p) Calcination time is 1 to 4 hours;

[0034] (q) The calcination treatment comprises a multi-stage calcination process, wherein the multi-stage calcination process comprises:

[0035] a first calcination step of calcining at a first temperature increase rate in an air atmosphere until the calcination reaches a first set temperature of 200 to 300° C.; and

[0036] In the second calcination step, the calcined product obtained in the first calcination step is calcined at a second temperature increase rate in an air atmosphere to a second set temperature of 500 to 600°C.

[0037] Wherein, the first heating rate is 1 to 10°C / min, and the second heating rate is 1 to 10°C / min;

[0038] The holding time of the first set temperature in the first calcination step is 0.5 to 2 hours, and the holding time of the second set temperature in the second calcination step is 2 to 4 hours.

[0039] [6]. A medium-temperature flue gas denitration catalyst, wherein the medium-temperature flue gas denitration catalyst is obtained according to the preparation method described in any one of [1] to [5].

[0040] [7] The medium-temperature flue gas denitration catalyst according to [6] is represented by the following formula (I):

[0041] M y Al z O x (I)

[0042] Wherein, M is iron, manganese, cerium, cobalt, nickel, copper, tin, lanthanum or zirconium,

[0043] x:y:z is (0.1~0.6):(0.1~0.6):1.

[0044] [8] The medium-temperature flue gas denitration catalyst according to [6] or [7], which is used for denitration at 150 to 400°C.

[0045] [9]. Application of the medium-temperature flue gas denitration catalyst according to any one of [6] to [8] in ammonia selective catalytic reduction technology.

[0046]

[10] A method for treating waste gas, comprising: treating the waste gas using the medium-temperature flue gas denitration catalyst obtained by the preparation method described in [1] to [5];

[0047] Preferably, the waste gas includes at least one of flue gas from thermal power plants, flue gas from industrial kilns, waste gas from cement manufacturing, waste incineration, waste gas from glass melting furnaces and waste gas from steel coke ovens.

[0048] Effects of the Invention

[0049] The main features and advantages of the present invention are as follows:

[0050] (1) The raw materials used in the synthesis of catalyst precursors (such as manganese salts, iron salts, aluminum salts and citric acid) are readily available, the conditions are easy to control and not harsh, the production cycle is short, there is almost no pollution to the environment, and mass production can be achieved.

[0051] (2) The catalyst preparation method of the present invention is simple and the catalyst activity is high.

[0052] (3) The catalyst of the present invention can still maintain high reaction activity in a wide reaction temperature range (200-400° C.), so that the catalyst can be used in harsh environments.

[0053] The catalyst of the present invention can successfully convert NO in flue gas waste gas that has an impact on the climate environment into N2, an inert gas that has no impact on the environment. The catalyst of the present invention can be applied to flue gas treatment in the medium temperature range. In addition, the catalyst preparation process of the present invention is pollution-free, the preparation process is simple to operate, the cycle is short, the industrial basis of the unit operation involved is mature, it is easy to carry out large-scale production, and the economic efficiency is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The test results of the catalysts of Examples 1 to 4 and Comparative Examples 1 to 2 in NH3-SCR (reaction temperature 150-400°C, reaction pressure normal pressure, NO and NH3 concentrations in the reaction gas are both 800 mg / m 3 , 6% O2, the rest N2, the reaction feed space velocity GHSV is 36000ml / g -1 / h -1 ).

[0055] Figure 2The test results of the catalysts of Examples 5 to 8 and Comparative Examples 3 to 4 in NH3-SCR (reaction temperature 150 to 400°C, reaction pressure normal pressure, NO and NH3 concentrations in the reaction gas are both 800 mg / m 3 , 6% O2, the rest N2, the reaction feed space velocity GHSV is 36000ml / g -1 / h -1 ).

[0056] Figure 3 The catalyst (Fe 1.2 Al 0.8 O x ) (reaction temperature 150 ~ 400 ℃, reaction pressure is atmospheric pressure, NO and NH3 concentrations in the reaction gas are 800mg / m 3 , 6% O2, the rest N2, the reaction feed space velocity GHSV is 36000ml / g -1 / h -1 ). DETAILED DESCRIPTION

[0057] Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The word "exemplary" used here means "used as an example, embodiment or illustrative". Any embodiment described here as "exemplary" is not necessarily interpreted as being superior or better than other embodiments.

[0058] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In other examples, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0059] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0060] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0061] In this specification, the references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0062] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0063]

[0064] The preparation method of the medium-temperature flue gas denitration catalyst of the present invention comprises:

[0065] Step A: mixing the active component metal salt, the aluminum source compound and the complexing agent and heating and drying them to obtain a catalyst precursor; and

[0066] Step B: calcining the catalyst precursor to obtain a denitration catalyst.

[0067] The present invention adopts a sol-gel method to prepare a medium-temperature flue gas denitration catalyst, wherein an active component metal salt (preferably an iron salt or a manganese salt) is used as a precursor, and is mixed with an aluminum source compound (preferably an aluminum salt) and a complexing agent (preferably citric acid) to prepare a mixed solution precursor, and the mixed solution precursor is heated to reflux, dried, and calcined to obtain a medium-temperature flue gas denitration catalyst.

[0068] The medium-temperature flue gas denitrification catalyst obtained by the preparation method of the present invention has high catalytic activity and can effectively remove NO from medium-temperature flue gas. x (NO, NO2, N2O), can adapt to the current situation of flue gas peak regulation and load reduction caused by flue gas temperature reduction, and achieve high denitrification activity. Moreover, the preparation method of the present invention has a simple process, easy-to-obtain raw materials, low environmental pollution, and economic cost with industrialization possibility.

[0069] Process A

[0070] In some preferred embodiments, step A preferably includes:

[0071] Step A1: mixing an active component metal salt, an aluminum source compound and a complexing agent to obtain a mixed solution precursor; and

[0072] Step A2: heating, stirring and drying the mixed solution precursor to obtain a catalyst precursor.

[0073] (Process A1)

[0074] As the active component in the active component metal salt, it is preferred to include at least one of iron, manganese, cerium, cobalt, nickel, copper, tin, lanthanum and zirconium, and more preferably include iron or manganese.

[0075] In some preferred embodiments, the metal salt of the active ingredient is preferably a soluble metal salt of the active ingredient, more preferably at least one of a nitrate, acetate and chloride salt of the active ingredient.

[0076] In some preferred embodiments, the active component metal salt includes at least one of ferric nitrate, ferric acetate, ferric chloride, manganese acetate, manganese nitrate, manganese chloride, cerium nitrate, cerium chloride, cobalt nitrate, cobalt acetate, cobalt chloride, nickel nitrate, nickel acetate, nickel chloride, copper nitrate, copper acetate, copper chloride, tin tetrachloride, lanthanum nitrate, and zirconium nitrate.

[0077] The aluminum source compound is preferably an aluminum salt, more preferably a soluble aluminum salt.

[0078] In some preferred embodiments, the aluminum source compound includes aluminum nitrate, aluminum acetate, or aluminum chloride.

[0079] As the complexing agent, it is preferred to include at least one of substances having two or more carboxyl groups such as citric acid, oxalic acid, etc.; substances having one carboxyl group such as acetic acid, etc.; substances having two or more amino groups such as acetylacetonate, ethylenediamine, etc.; substances having two or more hydroxyl groups such as ethylene glycol, etc.

[0080] In some preferred embodiments, the molar ratio of the active component metal salt to the aluminum source compound is 0.2: 1 to 4: 1. By setting the molar ratio of the active component metal salt to the aluminum source compound within the above range, the activity of the denitration catalyst can be improved, and the denitration catalyst obtained can maintain high reaction activity in a wide reaction temperature range (200 to 400° C.).

[0081] In some specific embodiments, the molar ratio of the active component metal salt to the aluminum source compound is 0.2:1, 0.25:1, 0.5:1, 0.75:1, 1:1, 1.25:1, 1.5:1, 1.75:1, 2:1, 2.25:1, 2.5:1, 2.75:1, 3:1, 3.25:1, 3.5:1, 3.75:1 or 4:1.

[0082] In some preferred embodiments, the molar ratio of the active component metal salt to the complexing agent is 0.2: 1 to 1: 1. By setting the molar ratio of the active component metal salt to the complexing agent within the above range, the activity of the denitration catalyst can be improved, and the denitration catalyst obtained can maintain high reaction activity in a wide reaction temperature range (200 to 400° C.).

[0083] In some specific embodiments, the molar ratio of the active component metal salt to the complexing agent is 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1:1.

[0084] (Process A2)

[0085] In some preferred embodiments, the heating temperature is preferably 110 to 130° C. By setting the heating temperature within the above range, the activity of the denitration catalyst can be improved, and the denitration catalyst obtained can maintain high reaction activity in a wide reaction temperature range (200 to 400° C.).

[0086] In some preferred embodiments, the heating and stirring time is preferably 2 to 6 hours. By setting the heating and stirring time within the above range, the activity of the denitration catalyst can be improved, and the denitration catalyst obtained can maintain high reaction activity in a wide reaction temperature range (200 to 400° C.).

[0087] There is no particular limitation on the stirring method, and for example, mechanical stirring or magnetic stirring may be used.

[0088] In some preferred embodiments, the drying temperature is preferably 100 to 130° C. The drying time is preferably 4 to 12 hours. By setting the drying temperature and the drying time within the above ranges, the activity of the denitration catalyst can be improved, and the denitration catalyst obtained can maintain high reaction activity in a wide reaction temperature range (200 to 400° C.).

[0089] In the present invention, after the above drying, a porous powder solid is obtained.

[0090] (Process B)

[0091] In step B, the catalyst precursor obtained above is calcined to obtain a medium-temperature flue gas denitration catalyst.

[0092] In some preferred embodiments, the calcination temperature is preferably 400-600°C; the calcination time is preferably 1-4 hours. In some specific embodiments, the calcination temperature is 400°C, 500°C or 600°C; the calcination time is 1 hour, 2 hours, 3 hours or 4 hours. By setting the calcination temperature and calcination time within the above range, the denitration performance can be fully improved, and the denitration catalyst obtained can maintain high reaction activity in a wide reaction temperature range (200-400°C).

[0093] In some preferred embodiments, the calcination treatment may include a multi-stage calcination process, which includes the following processes: a first calcination process, calcining in a calcination furnace, in an air atmosphere, at a first heating rate to a first set temperature of 200 to 300° C.; and a second calcination process, calcining the calcined product obtained by the first calcination process in a calcination furnace, in an air atmosphere, at a second heating rate to a second set temperature of 500 to 600° C. Here, the first heating rate is preferably in the range of 1 to 10° C. / min, and the second heating rate is in the range of 1 to 10° C. / min.

[0094] From the perspective of obtaining a better denitration catalyst, the holding time of the first set temperature in the first calcination step is preferably 0.5 to 2 hours. The holding time of the first set temperature refers to the time for maintaining the first set temperature after reaching the first set temperature. The holding time of the second set temperature in the second calcination step is preferably 2 to 4 hours. The holding time of the second set temperature refers to the time for maintaining the second set temperature after reaching the second set temperature.

[0095] (Medium temperature flue gas denitrification catalyst)

[0096] The present invention provides a medium-temperature flue gas denitration catalyst, which is a medium-temperature flue gas denitration catalyst obtained according to the preparation method of the present invention.

[0097] The medium-temperature flue gas denitrification catalyst of the present invention can maintain high reaction activity in a wide reaction temperature range (200-400°C), can exert a high denitrification effect, can effectively adapt to the current situation of flue gas peak regulation and load reduction caused by the reduction of flue gas temperature, and can be used for flue gas treatment in the medium temperature range.

[0098] When the medium-temperature flue gas denitration catalyst of the present invention is used in NH3-SCR with a reaction temperature of 150 to 400°C, a NO x Conversion rate.

[0099] In some preferred embodiments, the denitration catalyst of the present invention is preferably represented by the following formula (I):

[0100] M y Al z O x (I)

[0101] Wherein, M is iron, manganese, cerium, cobalt, nickel, copper, tin, lanthanum or zirconium,

[0102] x:y:z is (0.1~0.6):(0.1~0.6):1.

[0103] <Application of Medium Temperature Flue Gas Denitrification Catalyst in Ammonia Selective Catalytic Reduction Technology (NH3-SCR)>

[0104] The present invention also provides the use of the medium-temperature flue gas denitration catalyst obtained according to the preparation method of the present invention in ammonia selective catalytic reduction technology (NH3-SCR).

[0105]

[0106] The present invention provides a method for treating waste gas, which comprises: treating the waste gas using a medium-temperature flue gas denitration catalyst obtained by the preparation method of the present invention.

[0107] In some preferred embodiments, the above-mentioned waste gas includes flue gas from thermal power plants, flue gas from industrial kilns, waste gas from cement manufacturing, waste incineration, waste gas from glass melting furnaces, waste gas from steel coke ovens, etc.

[0108] Example

[0109] The embodiments of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0110] Example 1

[0111] (1) 2.2 g of ferric nitrate, 0.5 g of aluminum nitrate, and 1.4 g of citric acid were mixed in 50 mL of deionized water and stirred continuously for 0.5 h to obtain a mixed solution precursor.

[0112] (2) The obtained mixed solution precursor was continuously stirred for 2.5 h under reflux heating at a heating temperature of 120° C. and dried at 120° C. overnight to form a porous powder solid.

[0113] (3) The porous powder solid was ground and the ground sample was calcined at 200°C for 1 h and 500°C for 2 h. The calcination process was controlled by programmed temperature increase at a heating rate of 1°C / min to obtain Fe 1.6 Al 0.4 O3 catalyst.

[0114] Example 2

[0115] A denitration catalyst was prepared in the same manner as in Example 1, except that the amount of ferric nitrate added in step (1) was changed to 1.6 g and the amount of aluminum nitrate added was changed to 1.0 g. 1.2 Al 0.8 O3 catalyst.

[0116] Example 3

[0117] The denitration catalyst was prepared in the same manner as in Example 1 except that the amount of ferric nitrate added in step (1) was changed to 1.1 g and the amount of aluminum nitrate added was changed to 1.5 g. 0.8 Al 1.2 O3 catalyst.

[0118] Example 4

[0119] A denitration catalyst was prepared in the same manner as in Example 1, except that the amount of ferric nitrate added in step (1) was changed to 0.54 g and the amount of aluminum nitrate added was changed to 2.0 g. 0.4 Al 1.6 O3 catalyst.

[0120] Example 5

[0121] (1) 1.3 g of manganese acetate, 0.5 g of aluminum nitrate, and 1.4 g of citric acid were mixed in 50 mL of deionized water and stirred continuously for 0.5 h to obtain a mixed solution precursor.

[0122] (2) The obtained mixed solution precursor was continuously stirred for 2.5 h under reflux heating at a heating temperature of 120° C. and dried at 120° C. overnight to form a porous powder solid.

[0123] (3) The porous powder solid was ground and the ground sample was calcined at 200°C for 1 h and 500°C for 2 h. The calcination process was controlled by programmed temperature increase at a heating rate of 1°C / min to obtain Mn 1.6 Al 0.4 O3 catalyst.

[0124] Example 6

[0125] A denitration catalyst was prepared in the same manner as in Example 5, except that the amount of manganese acetate added in step (1) of Example 5 was changed to 0.98 g and the amount of aluminum nitrate added was changed to 1.0 g. Finally, Mn 1.2 Al 0.8 O3 catalyst.

[0126] Example 7

[0127] A denitration catalyst was prepared in the same manner as in Example 5, except that the amount of manganese acetate added in step (1) of Example 5 was changed to 0.65 g and the amount of aluminum nitrate added was changed to 1.5 g. Finally, Mn 0.8 Al 1.2 O3 catalyst.

[0128] Example 8

[0129] A denitration catalyst was prepared in the same manner as in Example 5, except that the amount of manganese acetate added in step (1) of Example 5 was changed to 0.33 g and the amount of aluminum nitrate added was changed to 2.0 g. Finally, Mn 0.4 Al 1.6 O3 catalyst.

[0130] Comparative Example 1

[0131] Except that the amount of iron nitrate added in step (1) was changed to 2.7 g and the amount of aluminum nitrate added was changed to 0 g, a denitration catalyst was prepared in the same manner as in Example 1, and finally a Fe2Al0O3 catalyst was obtained.

[0132] Comparative Example 2

[0133] A denitration catalyst was prepared in the same manner as in Example 1, except that the amount of iron nitrate added in step (1) was changed to 0 g and the amount of aluminum nitrate added was changed to 2.5 g, and finally a Fe0Al2O3 catalyst was obtained.

[0134] Comparative Example 3

[0135] A denitration catalyst was prepared in the same manner as in Example 5, except that the amount of manganese acetate added in step (1) of Example 5 was changed to 1.6 g and the amount of aluminum nitrate added was changed to 0 g, and finally a Mn2Al0O3 catalyst was obtained.

[0136] Comparative Example 4

[0137] A denitration catalyst was prepared in the same manner as in Example 5, except that the amount of manganese acetate added in step (1) of Example 5 was changed to 0 g and the amount of aluminum nitrate added was changed to 2.5 g, and finally a Mn0Al2O3 catalyst was obtained.

[0138] <Catalyst Evaluation Method>

[0139] In this article, the reaction volume space velocity is defined as the volume flow rate of the reaction gas raw material (base) entering the reaction system per hour divided by the mass of the catalyst, expressed as GHSV, in units of ml / g -1 / h -1 .

[0140] Flue gas analyzer: Ecom J2KN

[0141] Can measure NO, NO2, N2O, O2

[0142] 500 mg of each catalyst sample in the above examples were placed in the constant temperature zone of the fixed bed reactor. The temperature controller was adjusted to make the reaction temperature reach 150-400°C, and the mass flow meter was adjusted to 300 mL / min (standard condition). When the temperature was stable, the reaction was started. The product was analyzed online, and samples were taken once every minute.

[0143] Table 1 shows the performance results of the catalyst for NH3-SCR reaction (reaction temperature 150-400°C, reaction pressure is atmospheric pressure, raw gas molar composition: NO and NH3 concentrations in the reaction gas are both 800 mg / m 3 , 6% O2, the rest N2, the reaction feed space velocity GHSV is 36000ml / g -1 / h -1 ).

[0144] The NO conversion rate was calculated according to the following formula (1):

[0145]

[0146] Among them, NO in is the NO concentration at the inlet of the reaction tube, NO out is the NO concentration at the outlet of the reaction tube.

[0147] The N2 selectivity is calculated according to the following formula (2):

[0148]

[0149] Among them, NO in is the NO concentration at the inlet of the reaction tube, NO out is the NO concentration at the outlet of the reaction tube, N 2out is the N2 concentration at the outlet of the reaction tube, NH 3in is the NH3 concentration at the reactor inlet, NH 3out is the NH3 concentration at the outlet of the reaction tube.

[0150] Table 1

[0151]

[0152] It can be seen from Table 1 that the catalyst of the present invention can achieve flue gas denitration in the medium temperature range (150-400° C.).

[0153] Depend on Figure 1 It can be seen that in the NH3-SCR reaction process, the iron-based catalysts prepared in Examples 1 to 4 have high SCR activity in the range of 200 to 400°C.

[0154] When the temperature is reduced to 150°C, manganese-based catalysts can be used. Figure 2 As shown, the manganese-based catalysts prepared in Examples 5 to 8 have high NO conversion rates.

[0155] Figure 3 The N2 selectivity (N2 selectivity) of the iron-based catalyst of Example 2 is shown. Figure 3As shown, the iron-based catalyst prepared in Example 2 has excellent N2 selectivity in the range of 200-400°C.

[0156] In addition, the manganese-based catalyst (Mn 1.2 Al 0.8 O3) The N2 selectivity at 150°C is 90%, and the N2 selectivity at 200°C is 78%. The manganese-based catalyst prepared in Example 6 has a high N2 selectivity in the reaction temperature range (150-200°C).

[0157] The iron / manganese catalyst prepared according to the present invention has good reaction stability and can adapt to harsh reaction environments. The catalyst preparation method involved in the present invention can be used for NH3-SCR reaction. The preparation method is simple and suitable for industrial scale-up. At the same time, the preparation method is environmentally friendly.

[0158] It should be noted that, although the technical solution of the present invention is introduced with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0159] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a medium-temperature flue gas denitration catalyst, characterized in that: It includes: Step A: mixing the active component metal salt, the aluminum source compound and the complexing agent and heating and drying them to obtain a catalyst precursor; and Step B: calcining the catalyst precursor to obtain a denitration catalyst.

2. The preparation method according to claim 1, characterized in that: The process A comprises: Step A1: mixing the active component metal salt, the aluminum source compound and the complexing agent to obtain a mixed solution precursor; and Step A2: heating, stirring and drying the mixed solution precursor to obtain a catalyst precursor.

3. The preparation method according to claim 2, characterized in that: The step A or step A1 satisfies at least one of the following characteristics (a) to (j): (a) the active component in the active component metal salt includes at least one of iron, manganese, cerium, cobalt, nickel, copper, tin, lanthanum and zirconium; (b) the active component metal salt is a soluble metal salt of the active component; (c) the active component metal salt is at least one of a nitrate, an acetate and a chloride of the active component; (d) the active component metal salt includes at least one of ferric nitrate, ferric acetate, ferric chloride, manganese acetate, manganese nitrate, manganese chloride, cerium nitrate, cerium chloride, cobalt nitrate, cobalt acetate, cobalt chloride, nickel nitrate, nickel acetate, nickel chloride, copper nitrate, copper acetate, copper chloride, tin tetrachloride, lanthanum nitrate and zirconium nitrate; (e) the aluminum source compound is an aluminum salt; (f) the aluminum source compound comprises aluminum nitrate, aluminum acetate or aluminum chloride; (g) the complexing agent includes at least one of a substance having one or more carboxyl groups, a substance having two or more amino groups, and a substance having two or more hydroxyl groups; (h) the complexing agent comprises citric acid or oxalic acid; (i) the molar ratio of the active component metal salt to the aluminum source compound is 0.2:1 to 4:1; (j) The molar ratio of the active component metal salt to the complexing agent is 0.2:1 to 1:

1.

4. The preparation method according to claim 2, characterized in that: The process A or the process A2 satisfies at least one of the following characteristics (k) to (n): (k) The heating temperature is 110 to 130° C.; (l) Heating and stirring time is 2 to 6 hours; (m) drying temperature is 100 to 130°C; (n) Drying time is 4 to 12 hours.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The process B satisfies at least one of the following characteristics (o) to (q): (o) calcination temperature is 400 to 600°C; (p) Calcination time is 1 to 4 hours; (q) The calcination treatment comprises a multi-stage calcination process, wherein the multi-stage calcination process comprises: a first calcination step of calcining at a first temperature increase rate in an air atmosphere until the calcination reaches a first set temperature of 200 to 300° C.; and The second calcination step is to calcine the calcined product obtained in the first calcination step at a second temperature increase rate in an air atmosphere until it reaches a second set temperature of 500 to 600° C., Wherein, the first heating rate is 1 to 10°C / min, and the second heating rate is 1 to 10°C / min; The holding time of the first set temperature in the first calcination step is 0.5 to 2 hours, and the holding time of the second set temperature in the second calcination step is 2 to 4 hours.

6. A medium-temperature flue gas denitration catalyst, characterized in that: The medium-temperature flue gas denitration catalyst is obtained according to the preparation method described in any one of claims 1 to 5.

7. The medium-temperature flue gas denitration catalyst according to claim 6, characterized in that: It is represented by the following formula (I): M y Al z O x (I) Wherein, M is iron, manganese, cerium, cobalt, nickel, copper, tin, lanthanum or zirconium, x:y:z is (0.1~0.6):(0.1~0.6):

1.

8. The medium-temperature flue gas denitration catalyst according to claim 6 or 7, characterized in that: It is used for denitrification at 150-400°C.

9. Use of the medium-temperature flue gas denitration catalyst according to any one of claims 6 to 8 in ammonia selective catalytic reduction technology.

10. A method for treating waste gas, characterized in that: It includes: Treating exhaust gas using the medium-temperature flue gas denitration catalyst obtained by the preparation method according to claims 1 to 5; Preferably, the waste gas includes at least one of flue gas from thermal power plants, flue gas from industrial kilns, waste gas from cement manufacturing, waste incineration, waste gas from glass melting furnaces and waste gas from steel coke ovens.

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