CN105126826B - A kind of FCC regenerated flue gas denitration manganese oxide/titanium dioxide catalyst and its production and use - Google Patents

Abstract

The invention provides a manganese oxide/titania catalyst for FCC (catalytic cracking) regeneration flue gas denitrification and its preparation method and application. The manganese oxide/titania catalyst is prepared by hydrothermal method: a solution containing a titanium source is mixed with Source, pore expander and optionally ammonium sulfate solution are mixed for hydrothermal reaction, the reaction product is subjected to solid-liquid separation, the obtained solid is washed, dried and calcined to obtain a manganese oxide/titanium dioxide catalyst. The manganese oxide/titanium dioxide catalyst is a nano-scale supported oxide catalyst with good dispersion of active components, simple preparation method, wide activity temperature window (150-350°C, denitrification efficiency greater than 90%), and high low-temperature activity. Good (under the condition of 150 ℃, the denitrification efficiency reaches 98%), and has the advantages of large comparative area, high thermal stability and high _N2 selectivity, and has a good application prospect.

Description

A kind of manganese oxide/titanium dioxide catalyst for denitrification of FCC regeneration flue gas and preparation method thereof law and use

technical field

The invention belongs to the technical field of catalysts, and relates to a manganese oxide/titania catalyst for FCC regeneration flue gas denitrification, a preparation method and application thereof.

Background technique

Catalytic cracking (FCC) unit is an important unit in the deep processing of crude oil, and occupies a pivotal position in the oil refining industry. During the catalytic cracking reaction, when the raw oil cracks, 30% to 50% of the nitrogen-containing compounds enter the oil coke, and then deposit on the surface of the catalyst. The activity of the catalyst is reduced due to the oil coke attached to the surface, so it must be regenerated. During the coking process of the regenerator, most nitrogen-containing compounds are converted into N ₂ , but 10% to 30% are also converted into NO _X , which are discharged with the regeneration flue gas. The main component is NO, with a volume percentage of about 90%, and the remaining About 10% is NO ₂ . According to different raw materials and operating conditions, the concentration of NO _X in the regenerated flue gas is also different, but it is generally higher than the 420mg/m ³ required in the "Comprehensive Emission Standard of Air Pollutants" (GB16297-1996) (for devices built before 1997 ) and 240mg/m ³ (devices built in and after 1997), and none of them are equipped with flue gas denitrification facilities.

On the other hand, due to the rapid development of the crude oil processing industry and the adverse effects of crude oil degradation, the NO _X emissions of refineries are increasing. Typically, regeneration flue gas is the main source of NO _X emissions from refineries, accounting for about 50% of their total emissions. Up to now, PetroChina has 41 FCC units with a total production capacity of 50.8 million tons per year, total regeneration flue gas emission of more than 5 million Nm ³ /h, and annual NO _X emission of about 12,000 tons. If the flue gas denitrification technology is used to treat it, based on the _NOx removal rate of 80%, this alone can reduce the _NOx emission of the group company by 10%. It can be seen that the NO _X emission problem in FCC regeneration flue gas has become a common problem in all refineries of PetroChina, which seriously restricts the advancement of energy conservation, emission reduction and clean production of PetroChina.

It can be predicted that with the increasingly stringent environmental protection standards, the production demand for FCC regenerative flue gas denitrification technology will expand rapidly in various refineries of PetroChina.

At present, the FCC regenerative flue gas denitrification technologies that have been industrially applied at home and abroad include: low NO _X coking technology, oxidation absorption method, additive method, selective non-catalytic reduction (SNCR) method and selective catalytic reduction (SCR) method . The five FCC regenerative flue gas denitrification technologies have different characteristics and are suitable for different treatment conditions and treatment requirements, so they need to be selected according to local conditions. However, as far as the existing 41 sets of FCC units in China are concerned, the Selective Catalytic Reduction (SCR) method is undoubtedly the most effective method due to its stable treatment effect, wide application range and mature process, if the denitrification problem of the regenerated flue gas is to be solved as a whole. competitive technology.

Traditional SCR catalysts include noble metal catalysts, metal oxide catalysts and molecular sieve catalysts. In recent years, oxide catalysts have attracted extensive attention due to their short preparation cycle, low cost, and easy operation. Vanadium-based SCR catalysts have been used industrially for stationary source denitrification for many years, but there are still problems such as high operating temperature, narrow operating temperature window, a large amount of N ₂ O generated at high temperature, resulting in a decrease in N ₂ selectivity, and the oxidation of SO ₂ to SO ₃ , etc. question. Therefore, the main way to solve these problems is to develop low-temperature SCR catalysts that can greatly reduce the cost and to find non-vanadium oxide catalysts. In recent years, manganese-based catalysts with better low-temperature activity have higher low-temperature catalytic activity and selectivity for NH ₃ -SCR reaction, so they have attracted much attention and become a type of denitration catalyst that has been studied more.

Li Huijie studied the performance of MnOx-TiO ₂ catalytic oxidation of NO, mainly investigated the catalytic oxidation of single active component MnOx to NO and the influence of H ₂ O and SO ₂ on the catalyst activity, and analyzed the mechanism of catalyst poisoning. The research results show that the best conditions for preparing MnOx-TiO ₂ catalyst by impregnation method are: Mn content 20% (wt%), calcination at 300°C for 6h, the catalyst prepared under this condition has very high catalytic oxidation activity of NO: the space velocity is The conversion rate of NO is as high as 89% when the reaction temperature is 10000h ^-1 and the reaction temperature is 300°C (Xiangtan University, 2011, master's degree thesis).

Li Junhua and others studied the influence of MnOx/TiO ₂ prepared by different manganese sources on the NO reduction reaction, and found that the MnOx obtained by using manganese nitrate as the manganese source is mainly MnO ₂ ; the MnOx obtained by using manganese acetate as the manganese source is mainly Mn ₂ O ₃ (Effects of precursors on the surface Mn species and the activities for NOreduction over MnOx/TiO ₂ catalysts, Catalysis Communications, 2007,12(8):1896–1900).

Xu Haitao and others studied the preparation of MnOx/TiO ₂ catalyst and its low-temperature NH ₃ selective catalytic reduction of NO performance. They used the microemulsion method to prepare nano-TiO ₂ with different crystal phases at different calcination temperatures, and used it as a carrier. A series of MnOx/TiO ₂ catalysts were prepared by impregnation method. The experimental results show that as the calcination temperature increases, the nano-TiO ₂ gradually transforms from the anatase type to the rutile type. The nano-TiO ₂ obtained by calcination at 700°C is in a mixed crystal phase, and the nano-TiO ₂ obtained by calcination at 800°C is a pure rutile type. ; The interaction between the anatase and mixed phase TiO ₂ support and the active oxide MnO ₂ is relatively strong. When the rutile and anatase coexist in the nano-TiO ₂ , the MnO ₂ interacts preferentially with the anatase nano-TiO ₂ ; The interaction between pure rutile nano-TiO ₂ and MnOx is weak, simulated NH, the reactivity test results of selective catalytic reduction of NO show that the MnOx/TiO ₂ catalyst calcined at 500 ° C shows a higher low-temperature activity ( Journal of Southeast University: Natural Science Edition, 2012, 3, 463-467).

CN 102553573 A discloses a nitrogen oxide catalyst. The active component of the catalyst is manganese oxide, and the manganese oxide is supported on an inorganic carrier, or manganese oxide and one of cobalt oxide, cerium oxide, and copper oxide or At least two composite metal oxide catalysts are used. The carrier is an inorganic oxide carrier, preferably silicon dioxide, aluminum oxide, titanium dioxide or a mixture thereof, preferably aluminum oxide or titanium dioxide, more preferably titanium dioxide. The nitrogen oxide catalyst can realize the conversion of nitrogen oxides (such as NO, N ₂ O, etc.) into nitrogen dioxide at a relatively low temperature under the condition of the presence of oxygen. The catalyst is prepared by co-precipitation method or impregnation method, and its main active component is manganese oxide. Applying it to the purification test of simulated flue gas with a NO concentration of 200ppm, the conversion of NO to NO ₂ can be realized at a lower temperature, and the NO ₂ enters the desulfurization tower and further reacts with the desulfurizer to realize the nitrogen oxidation in the flue gas removal of matter.

CN 102319560 A discloses a method for preparing a manganese-titanium catalyst. Manganese nitrate and titanium dioxide are used as raw materials, added to deionized water, mixed and stirred, ultrasonically treated, dried and roasted to obtain a manganese-titanium catalyst, wherein the manganese-titanium catalyst The titanium catalyst uses titanium oxide as the carrier and manganese oxide as the active component. The denitrification efficiency of Mn/ _{TiO 2} (UI) series catalysts can reach about 70% at 80°C, and Mn/TiO ₂ (SG) also shows good reactivity. The required temperature for NO removal rate should be above 150°C.

It can be seen that the low-temperature denitration performance of manganese-based oxide catalysts is not ideal, and it is still an urgent problem to find manganese-based oxide catalysts with lower denitrification temperature and wider active temperature range.

Contents of the invention

The object of the present invention is to provide a manganese oxide/titania catalyst for FCC regeneration flue gas denitrification and its preparation method and application. The manganese oxide/titania catalyst is prepared by a hydrothermal method and is a nanoscale supported oxide The catalyst, the active component manganese oxide is directly dispersed in the skeleton of titanium dioxide, the dispersion is good, and the titanium dioxide in the catalyst is an anatase crystal form with high crystallinity. The denitrification efficiency in the range is stable above 90%; and at 125°C, the denitrification efficiency is greater than 90%; at 150°C, the denitrification efficiency reaches 98%.

For reaching this purpose, the present invention adopts following technical scheme:

The "/" in the manganese oxide/titania catalyst described in the present invention means "and", and the manganese oxide/titania catalyst is a composite catalyst of manganese oxide and titanium dioxide.

One of the purposes of the present invention is to provide a preparation method of manganese oxide/titania catalyst for FCC regeneration flue gas denitrification, the preparation method is: the solution containing titanium source and containing manganese source, pore expander and optionally sulfuric acid Ammonium solutions are mixed, hydrothermal reaction is carried out, the reaction product is subjected to solid-liquid separation, and the obtained solid is washed, dried and calcined to obtain a manganese oxide/titanium dioxide catalyst.

The manganese oxide/titania catalyst is doped with manganese in situ by a hydrothermal synthesis method, and is a nanoscale supported oxide catalyst, with manganese oxide as the active component and titanium dioxide as the carrier, wherein titanium dioxide is the crystallinity Higher anatase crystal titanium dioxide, the active component manganese oxide is directly dispersed in the skeleton of the titanium dioxide carrier, so the dispersion of the active component is good.

The solvent of the solution containing the titanium source is a mixed solution of acetylacetone and absolute ethanol. The solvents of the solutions containing the titanium source are different. Although the composition of the final product is relatively similar, the proportion of MnO ₂ in the active component is reduced, and the catalytic activity of MnO ₂ is the best, so the catalyst activity will be reduced.

Preferably, the volume ratio of the titanium source, acetylacetone and absolute ethanol is 5:(1-5):(10-15), such as 5:2:11, 5:3:12, 5:4:14 Or 5:2:14 etc.

Preferably, the titanium source is tetrabutyl titanate and/or titanium isopropoxide.

The mass ratio of manganese source, ammonium sulfate, pore expander and solvent in the solution containing manganese source, pore expander and ammonium sulfate is: (0.8～3.5):1:(3～8):(10 ~30), such as 1:1:3:15, 2:1:4:20, 2.5:1:6:25 or 3:1:7:28, etc.

The addition of the ammonium sulfate can improve the stability of the intergranular pores.

Preferably, the manganese source is manganese nitrate and/or manganese acetate.

Preferably, the pore-enlarging agent is one or a combination of at least two of urea, ammonium bicarbonate or ammonium carbonate, typical but non-limiting combinations are urea and ammonium bicarbonate, urea and ammonium carbonate, ammonium bicarbonate with ammonium carbonate etc. The addition of the pore-enlarging agent can increase the pore size and specific surface area of the final catalyst, and can better disperse the active components on the carrier, improving the activity of the catalyst; without adding the pore-enlarging agent, the catalytic activity will decrease.

Preferably, the solvent of the solution containing manganese source, pore expander and optionally ammonium sulfate is deionized water.

The mixing specifically includes: adding the solution containing the manganese source, the pore expander and optionally ammonium sulfate into the solution containing the titanium source through a membrane diffuser to obtain a mixed solution. the use of a membrane diffuser to allow a controlled mixing process of a solution containing a source of titanium with a solution containing a source of manganese, a pore expander and optionally ammonium sulphate, resulting in a better dispersion of the active ingredient on the support in the final product, The distribution is more uniform, which is conducive to improving the activity of the catalyst.

Preferably, the membrane diffuser includes a ceramic membrane tube, and the size of the pores on the ceramic membrane tube is 35-45nm, such as 36nm, 37nm, 38nm, 40nm, 42nm or 44nm.

Preferably, the membrane diffuser is respectively connected with a peristaltic pump and a gas input device.

Preferably, the gas flow rate in the gas input device is 10-100mL/min, such as 15mL/min, 20mL/min, 50mL/min, 60mL/min, 70mL/min, 80mL/min or 90mL/min, etc.

Preferably, the gas in the gas input device is nitrogen.

The temperature of the hydrothermal reaction is 80-120°C, such as 85°C, 90°C, 95°C, 100°C, 105°C, 110°C or 115°C. The higher the temperature of the hydrothermal reaction, the larger the crystal grains of the catalyst; the lower the temperature of the hydrothermal reaction, the smaller the crystal grains of the catalyst.

Preferably, the time for the hydrothermal reaction is 20-30 hours, such as 22 hours, 23 hours, 25 hours, 26 hours, 27 hours or 29 hours.

The manganese oxide/titanium dioxide catalyst prepared by the hydrothermal method is a nano-scale catalyst with a large specific surface area, and the titanium dioxide is all in the anatase crystal form, and the anatase crystal form titanium dioxide contains more defects and sites. Wrong, more oxygen vacancies can be generated, and this part of the vacancies is easy to absorb oxygen, which is beneficial to the oxidation-reduction reaction, so its catalyst activity is good, and the dispersion of active components is good.

Solid-liquid separation after hydrothermal reaction is a common operation in the field, and a typical but non-limiting solid-liquid separation method is centrifugation.

The solvent used in the washing is deionized water. The number of times of washing is not limited, and those skilled in the art can choose according to actual needs.

Preferably, the drying temperature is 100-150°C, such as 105°C, 110°C, 115°C, 120°C, 125°C, 130°C or 140°C, etc., and the drying time is 5-10h, such as 6h, 7h, 8h, 9h or 10h etc.

Preferably, the temperature of the calcination is 350-450°C, such as 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C or 445°C, and the time is 3-450°C. 6h, such as 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, etc.

Preferably, the calcination is carried out in an air atmosphere, and the heating rate is 1-2° C./min.

As a preferred technical solution, the preparation method includes the following steps:

(1) Add titanium source and acetylacetone to absolute ethanol and mix to obtain a solution containing titanium source, wherein the volume ratio of titanium source, acetylacetone and absolute ethanol is 5:(1～5):(10～ 15); adding manganese source, pore expander and optionally ammonium sulfate into deionized water for dissolving, to obtain manganese source, pore expander and optionally ammonium sulfate, wherein, manganese source, ammonium sulfate, pore expander The mass ratio to deionized water is (0.8～3.5):1:(3～8):(10～30);

(2) Add the solution containing manganese source, pore-enlarging agent and ammonium sulfate to the solution containing titanium source through a membrane diffuser to obtain a mixed solution, wherein the flow rate of gas in the membrane diffuser is 10-100mL/ min;

(3) Transfer the mixed solution to an autoclave for hydrothermal reaction. The temperature of the hydrothermal reaction is 80-120° C., and the time is 20-30 hours. The hydrothermal reaction product is subjected to solid-liquid separation. Dry at 150°C for 5-10 hours, and then bake at 350-450°C for 3-6 hours in an air atmosphere to obtain a manganese oxide/titanium dioxide catalyst.

The second object of the present invention is to provide a manganese oxide/titania catalyst for denitrification of FCC regeneration flue gas, the manganese oxide/titania catalyst is prepared by the above-mentioned preparation method.

The active component of the manganese oxide/titania catalyst is manganese oxide, and the carrier is titanium dioxide.

The mass percentage of manganese oxide in the manganese oxide/titania catalyst in the manganese oxide/titania catalyst is 20-40%, such as 22%, 24%, 25%, 26%, 28%, 30%, 32%, 35% %, 37% or 39%, etc., preferably 35%.

Preferably, the manganese oxide in the manganese oxide/titania catalyst is one or a combination of at least two of MnO, Mn ₂ O ₃ or MnO ₂ .

Preferably, the particle size of the manganese oxide/titania catalyst is 10-30nm, such as 12nm, 15nm, 18nm, 20nm, 22nm, 25nm, 26nm, 28nm or 29nm.

The third object of the present invention is to provide a use of manganese oxide/titania catalyst, which is used in the field of FCC regeneration flue gas denitrification.

Compared with prior art, the beneficial effect of the present invention is:

The present invention adopts hydrothermal method to prepare manganese oxide/titania catalyst for FCC regeneration flue gas denitrification, and the prepared manganese oxide/titania catalyst is a nanoscale supported oxide catalyst, with manganese oxide as the active component and titanium dioxide as the active component. The carrier, and the titanium dioxide is anatase crystal titanium dioxide with high crystallinity, and the active component manganese oxide is directly dispersed in the skeleton of the titanium dioxide carrier, so the dispersion of the active component is good.

Compared with the common manganese oxide/titania catalyst, the manganese oxide/titania catalyst provided by the invention has a wider active temperature window in the SCR reaction for FCC regeneration flue gas denitrification (150-350°C, denitrification efficiency greater than 90%), It has good low-temperature activity (under the condition of 150°C, the denitrification efficiency reaches 98%), and has the advantages of large comparative area and high thermal stability.

The preparation method of the manganese oxide/titanium dioxide catalyst for FCC regeneration flue gas denitrification provided by the invention is simple, the preparation conditions are not harsh, the preparation period is short, and it has good application prospects.

Description of drawings

Fig. 1 is the carrier meso-TiO ₂ , Mn(20wt.%)/TiO ₂ , Mn(25wt.%)/TiO ₂ , Mn(30wt.%)/TiO ₂ , Mn(35wt.%) prepared in Example 1-6. %)/TiO ₂ and Mn(40wt.%)/TiO ₂ X-ray diffraction patterns.

Fig. 2 is the carrier meso-TiO ₂ , Mn(20wt.%)/TiO ₂ , Mn(25wt.%)/TiO ₂ , Mn(30wt.%)/TiO ₂ , Mn(35wt.%) prepared in Example 1-6. %)/TiO ₂ and Mn (40wt.%)/TiO ₂ BET diagrams, wherein, Figure 2a is the N adsorption _- desorption curves of catalysts with different Mn loadings; Figure 2b is the pore diameter of catalysts with different Mn loadings Distribution diagram; a, b, c, d, e and f in Fig. 2a and Fig. 2b indicate that the load of manganese oxide is 0, 20wt.%, 25wt.%, 30wt.%, 35wt.% and 40wt.% Mn/TiO ₂ series catalysts.

Fig. 3 is Mn(20wt.%)/TiO ₂ , Mn(25wt.%)/TiO ₂ , Mn(30wt.%)/TiO ₂ , Mn(35wt.%)/TiO ₂ and Mn (40wt.%)/TiO ₂ activity test results for selective catalytic reduction of NO.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

A, B and C in the following examples are only used to distinguish different solutions and have no other meanings.

Embodiment 1: preparation carrier meso-TiO ₂

(1) Add 20mL of tetrabutyl titanate and 4mL of acetylacetone to 60mL of absolute ethanol and stir thoroughly to obtain solution A; add 5g of ammonium sulfate and 20g of urea to 50mL of deionized water and stir thoroughly to obtain solution B.

(2) Add solution B to solution A to obtain solution C; the process of adding solution B to solution A is as follows: solution B enters the membrane diffuser under the action of a peristaltic pump, and at the same time starts the gas input device, nitrogen permeates The 40nm micropores on the two ceramic membrane tubes diffuse out of the membrane tubes, generating a large number of nitrogen bubbles to promote the complete mixing of the solution. The nitrogen flow rate is 10-100mL/min.

(3) Transfer solution C to an autoclave, react at 100°C for 24h, centrifuge the reacted product, wash and filter, then put it in a 120°C oven for 8h, and then bake it in a muffle furnace at 400°C for 4h, The carrier meso-TiO ₂ is obtained.

Embodiment 2: Mn(20wt.%)/TiO ₂ preparation of catalyst

(1) Add 10mL of tetrabutyl titanate and 2mL of acetylacetone to 20mL of absolute ethanol and stir thoroughly to obtain solution A; add 4.4734g of 50% manganese nitrate solution by mass, 2.5g of ammonium sulfate and 7.5g of urea Add it into 25mL of deionized water and stir well to obtain solution B.

(2) Add solution B to solution A to obtain solution C; the process of adding solution B to solution A is as follows: solution B enters the membrane diffuser under the action of a peristaltic pump, and at the same time starts the gas input device, and nitrogen passes through the two The 40nm micropores on the root ceramic membrane tube diffuse to the outside of the membrane tube, generating a large number of nitrogen bubbles to promote the complete mixing of the solution. The nitrogen flow rate is 10-100mL/min.

(3) Transfer solution C to an autoclave, crystallize at 80°C for 30h, centrifuge the crystallized product, wash, filter, dry in a 100°C oven for 10h, and roast in a muffle furnace at 350°C for 6h to obtain Mn( 20wt.%)/TiO ₂ catalyst (the mass ratio of manganese oxide to titanium dioxide is 20%).

Embodiment 3: Mn (25wt.%)/TiO ₂ preparation of catalyst

(1) Add 10mL tetrabutyl titanate and 10mL acetylacetone to 30mL absolute ethanol, stir thoroughly to obtain solution A; add 6.3236g manganese nitrate solution with a mass percentage of 50%, 2.5g ammonium sulfate and 20g urea into 75mL of deionized water and stirred thoroughly to obtain solution B.

(2) Add solution B to solution A to obtain solution C; the process of adding solution B to solution A is: enter the configured solution B into the membrane diffuser under the action of the peristaltic pump, and start the gas input device at the same time, nitrogen Diffuse through the 40nm micropores on the two ceramic membrane tubes to the outside of the membrane tubes to generate a large number of nitrogen bubbles to promote the complete mixing of the solution. The nitrogen flow rate is 10-100mL/min.

(3) Transfer solution C to an autoclave, crystallize at 120°C for 20 hours, centrifuge the crystallized product, wash, filter, then put it in an oven at 150°C for 5 hours, and bake it in a muffle furnace at 450°C for 3 hours. A Mn (25wt.%)/TiO ₂ catalyst (mass ratio of manganese oxide to titanium dioxide is 25%) is obtained.

Embodiment 4: Mn (30wt.%)/TiO ₂ preparation of catalyst

(1) Add 10mL of tetrabutyl titanate and 6mL of acetylacetone to 25mL of absolute ethanol, stir thoroughly to obtain solution A; mix 8.7321g of 50% manganese nitrate solution, 2.5g of ammonium sulfate and 13.75g of urea Add it into 50mL of deionized water and stir well to obtain solution B.

(2) Add solution B to solution A to obtain solution C; the process of adding solution B to solution A is: enter the configured solution B into the membrane diffuser under the action of the peristaltic pump, and start the gas input device at the same time, nitrogen Diffuse through the 40nm micropores on the two ceramic membrane tubes to the outside of the membrane tubes to generate a large number of nitrogen bubbles to promote the complete mixing of the solution. The nitrogen flow rate is 10-100mL/min.

(3) Transfer solution C to an autoclave, crystallize at 100°C for 25h, centrifuge the crystallized product, wash, filter, and then dry it in a 125°C oven for 7.5h, then bake it in a muffle furnace at 400°C After 4.5h, a Mn(30wt.%)/TiO ₂ catalyst was obtained (the mass ratio of manganese oxide to titanium dioxide was 30%).

Embodiment 5: Mn(35wt.%)/TiO ₂ preparation of catalyst

(1) Add 10mL of tetrabutyl titanate and 2mL of acetylacetone to 20mL of absolute ethanol, stir thoroughly to obtain solution A; mix 11.9934g of manganese nitrate solution with a mass percentage of 50%, 2.5g of ammonium sulfate and 7.5g of urea Add it into 25mL of deionized water and stir well to obtain solution B.

(2) Add solution B to solution A to obtain solution C; the process of adding solution B to solution A is: enter the configured solution B into the membrane diffuser under the action of the peristaltic pump, and start the gas input device at the same time, nitrogen Diffuse through the 40nm micropores on the two ceramic membrane tubes to the outside of the membrane tubes to generate a large number of nitrogen bubbles to promote the complete mixing of the solution. The nitrogen flow rate is 10-100mL/min.

(3) Transfer solution C to an autoclave, crystallize at 100°C for 25h, centrifuge the crystallized product, wash, filter, and then dry it in a 125°C oven for 7.5h, then bake it in a muffle furnace at 400°C After 4.5h, a Mn(35wt.%)/TiO ₂ catalyst was obtained (the mass ratio of manganese oxide to titanium dioxide was 35%).

Embodiment 6: Mn (40wt.%)/TiO ₂ preparation of catalyst

(1) Add 10mL tetrabutyl titanate and 2mL acetylacetone to 20mL absolute ethanol and stir thoroughly to obtain solution A; mix 16.6623g of 50% manganese nitrate solution, 2.5g of ammonium sulfate and 7.5g of urea Add it into 25mL of deionized water and stir well to obtain solution B.

(2) Add solution B to solution A to obtain solution C; the process of adding solution B to solution A is: enter the configured solution B into the membrane diffuser under the action of the peristaltic pump, and start the gas input device at the same time, nitrogen Diffuse through the 40nm micropores on the two ceramic membrane tubes to the outside of the membrane tubes to generate a large number of nitrogen bubbles to promote the complete mixing of the solution. The nitrogen flow rate is 10-100mL/min.

(3) Transfer solution C to an autoclave, crystallize at 120°C for 20h, centrifuge the crystallized product, wash, filter, then put it in an oven at 100°C for 10h, and then bake it in a muffle furnace at 450°C for 3h , to obtain Mn (40wt.%)/TiO ₂ catalyst (mass ratio of manganese oxide to titanium dioxide is 40%).

For the carrier meso-TiO ₂ , Mn(20wt.%)/TiO ₂ , Mn(25wt.%)/TiO ₂ , Mn(30wt.%)/TiO ₂ , Mn(35wt.%) prepared in Examples 1-6 )/TiO ₂ and Mn(40wt.%)/TiO ₂ were respectively subjected to XRD (Germany Bruker D8Advance series X-ray diffractometer) characterization, BET (Micromeritics ASAP 2020 automatic specific surface analyzer of Mike Company) characterization and catalytic activity test, the results As shown in Figure 1-3.

Wherein, the method for testing the activity of the catalyst is as follows: after the catalyst is pressed into tablets, it is ground and sieved, and the part of 40-60 mesh is taken. The experiment was carried out on a continuous-flow fixed-bed reactor. Specifically, 0.4 g of the sieved catalyst was loaded into a quartz glass tube, and the temperature inside the tube was controlled by a tube-type resistance furnace and a temperature controller for temperature programming. The mixed gas simulates real flue gas and is provided by its corresponding steel cylinder. The corresponding mixed gas composition is: C _NO = _CNH3 =1000ppm, CO ₂ =3%, the balance gas is N ₂ , and the volume space velocity is 16000h ^-1 . The concentration value of inlet and outlet NO was detected online by ThermoFisher 42iHL NO analyzer.

The specific calculation formula of NO conversion rate is as follows:

Among them, NO _in is the concentration of NO at the inlet (unit: ppm), and NO _out is the concentration of NO at the outlet (unit: ppm)

Fig. 1 is the carrier meso-TiO ₂ , Mn(20wt.%)/TiO ₂ , Mn(25wt.%)/TiO ₂ , Mn(30wt.%)/TiO ₂ , Mn(35wt.%) prepared in Example 1-6 .%)/TiO ₂ and Mn(40wt.%)/TiO ₂ X-ray diffraction patterns. The results show that the carrier meso-TiO prepared in Example ₁ is a pure anatase crystal form with high crystallinity; titanium dioxide is also a pure anatase crystal with high crystallinity in the catalyst prepared in Examples 2-6. type, and no diffraction peaks of manganese oxide were found, indicating that manganese oxide was well dispersed on the surface of the carrier.

Fig. 2 is the carrier meso-TiO ₂ , Mn(20wt.%)/TiO ₂ , Mn(25wt.%)/TiO ₂ , Mn(30wt.%)/TiO ₂ , Mn(35wt.%) prepared in Example 1-6 .%)/TiO ₂ and BET diagrams of Mn(40wt.%)/TiO ₂ . The results show that the carrier meso- _TiO2 prepared in Example 1 has a hysteresis loop shape that is a four-type curve _H2 type hysteresis loop, which is close to the three-dimensional cage-like pore structure, and the average pore diameter is 5.6nm; The hysteresis loop shape of the catalyst is also a four-type curve _H2 type hysteresis loop, which is close to the three-dimensional cage-like pore structure, and its average pore diameter is 5-10nm, indicating that the loading of manganese oxide does not block the pores of titanium dioxide.

Fig. 3 is Mn(20wt.%)/TiO ₂ , Mn(25wt.%)/TiO ₂ , Mn(30wt.%)/TiO ₂ , Mn(35wt.%)/TiO ₂ and Mn (40wt.%)/TiO ₂ activity test results for selective catalytic reduction of NO. The test results show that the denitrification efficiency of all catalysts is above 25% at 100°C; in the range of 100-150°C, with the increase of temperature, the denitrification efficiency of the catalyst increases significantly: at 125°C, the denitrification efficiency of the catalyst are all above 90%; at 150°C, the denitrification efficiency of the catalysts can reach 98%; and in the temperature range of 150-350°C, the denitrification efficiencies of all catalysts are stably maintained above 90%; it can be seen that the oxidation The low temperature activity of manganese/titania catalyst for selective catalytic reduction of NO is better, and its activity temperature range is wider.

It can also be seen from the figure that when the loading of manganese oxide in the manganese oxide/titanium dioxide catalyst is 35%, the catalytic activity of the catalyst is the best, the highest denitrification rate reaches 100%, and can be maintained at 90% at 100-350°C above conversion rate.

Comparative example 1

Except that the membrane diffuser mixing in step (2) is replaced by stirring mixing, all the other steps are the same as in Example 5. The prepared catalyst is marked as N-Mn(35wt.%)/TiO ₂ catalyst (the mass ratio of manganese oxide to titanium dioxide is 35%).

Using the same activity test method as in Example 5, N-Mn (35wt.%)/ _TiO was tested for the activity of selective catalytic reduction of NO. The results showed that the denitrification efficiency of the catalyst was above 90%. The active temperature range was 150 to 325 ℃.

Comparative example 2

A catalyst with a mass ratio of manganese oxide to titanium dioxide of 35% was prepared by co-precipitation method using the same raw material as in Example 5, and the prepared catalyst was marked as C-Mn(35wt.%)/TiO ₂ .

Adopt the activity testing method identical with embodiment 5 to C-Mn (35wt.%)/ _TiO Carry out the activity test of selective catalytic reduction NO, the result shows, the denitrification efficiency of catalyst is 200～250 in the active temperature range above 90%. ℃.

Comparative example 3

A catalyst with a mass ratio of manganese oxide to titanium dioxide of 35% was prepared by the impregnation method using the same raw material as in Example 5, and the prepared catalyst was marked as I-Mn(35wt.%)/TiO ₂ .

Adopt the activity test method identical with embodiment 5 to I-Mn (35wt.%)/ _TiO Carry out the activity test of selective catalytic reduction NO, the result shows that the denitrification efficiency of catalyst is 175～300 in the active temperature range of more than 90%. ℃.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and those skilled in the art should understand that any person skilled in the art should be aware of any disclosure in the present invention Within the technical scope, easily conceivable changes or substitutions all fall within the scope of protection and disclosure of the present invention.

Claims (23)

1. a kind of preparation method of manganese oxide/titania catalyst for FCC regeneration flue gas denitrification, it is characterized in that, described preparation method comprises the following steps: The solution containing the titanium source is mixed with the solution containing the manganese source, the pore-enlarging agent and ammonium sulfate, and the hydrothermal reaction is carried out, and the reaction product is subjected to solid-liquid separation, and the obtained solid is washed, dried, and roasted to obtain manganese oxide/ Titanium dioxide catalyst; The mixing specifically includes: adding a solution containing a manganese source, a pore-enlarging agent, and optionally ammonium sulfate to a solution containing a titanium source through a membrane diffuser to obtain a mixed solution; The pore-enlarging agent is one or a combination of at least two of urea, ammonium bicarbonate or ammonium carbonate; the temperature of the hydrothermal reaction is 80-120°C. 2. The preparation method according to claim 1, wherein the solvent of the solution containing the titanium source is a mixed solution of acetylacetone and absolute ethanol. 3. The preparation method according to claim 2, characterized in that, the volume ratio of the titanium source, acetylacetone and absolute ethanol is 5:(1～5):(10～15). 4. The preparation method according to claim 1, characterized in that, the titanium source is tetrabutyl titanate and/or titanium isopropoxide. 5. preparation method according to claim 1, is characterized in that, the mass ratio of described manganese source, ammonium sulfate, pore expander and solvent in the solution containing manganese source, pore expander and ammonium sulfate is: (0.8～3.5):1:(3～8):(10～30). 6. The preparation method according to claim 1, characterized in that, the manganese source is manganese nitrate and/or manganese acetate. 7. The preparation method according to claim 1, characterized in that, the solvent of the solution containing the manganese source, the pore-enlarging agent and optionally ammonium sulfate is deionized water. 8 . The preparation method according to claim 1 , wherein the membrane diffuser comprises ceramic membrane tubes, and the size of pores on the ceramic membrane tubes is 35-45 nm. 9. The preparation method according to claim 1, characterized in that, the membrane diffuser is respectively connected with a peristaltic pump and a gas input device. 10. The preparation method according to claim 9, characterized in that the gas flow rate in the gas input device is 10-100 mL/min. 11. The preparation method according to claim 9, characterized in that the gas in the gas input device is nitrogen. 12. The preparation method according to claim 1, characterized in that the time for the hydrothermal reaction is 20-30 hours. 13. The preparation method according to claim 1, characterized in that, the solvent used in the washing is deionized water. 14. The preparation method according to claim 1, characterized in that, the drying temperature is 100-150° C. and the drying time is 5-10 hours. 15. The preparation method according to claim 1, characterized in that the temperature of the calcination is 350-450° C. and the time is 3-6 hours. 16 . The preparation method according to claim 1 , wherein the calcination is carried out in an air atmosphere, and the heating rate is 1-2° C./min. 17. The preparation method according to claim 1, characterized in that, the preparation method comprises the steps of: (1) Add titanium source and acetylacetone to absolute ethanol and mix to obtain a solution containing titanium source, wherein the mass ratio of titanium source, acetylacetone to absolute ethanol is 5:(1～5):(10～15 ); adding the manganese source, the pore expander and optionally ammonium sulfate into deionized water for dissolving to obtain a solution containing the manganese source, the pore expander and optionally the ammonium sulfate, wherein the manganese source, the ammonium sulfate, the pore expander The mass ratio to deionized water is (0.8～3.5):1:(3～8):(10～30); (2) Add the solution containing manganese source, pore-enlarging agent and ammonium sulfate to the solution containing titanium source through a membrane diffuser to obtain a mixed solution, wherein the flow rate of gas in the membrane diffuser is 10-100mL/ min; (3) Transfer the mixed solution to an autoclave for hydrothermal reaction. The temperature of the hydrothermal reaction is 80-120° C., and the time is 20-30 hours. The hydrothermal reaction product is subjected to solid-liquid separation. Dry at 150°C for 5-10 hours, and then bake at 350-450°C for 3-6 hours in an air atmosphere to obtain a manganese oxide/titanium dioxide catalyst. 18. A manganese oxide/titania catalyst for denitrification of FCC regeneration flue gas, characterized in that the manganese oxide/titania catalyst is prepared according to the preparation method described in any one of claims 1-17. 19. The manganese oxide/titania catalyst according to claim 18, characterized in that the mass percentage of manganese oxide in the manganese oxide/titania catalyst in the manganese oxide/titania catalyst is 20-40%. 20. The manganese oxide/titania catalyst according to claim 18, characterized in that the mass percentage of manganese oxide in the manganese oxide/titania catalyst in the manganese oxide/titania catalyst is 35%. 21. The manganese oxide/titania catalyst according to claim 18, characterized in that, the manganese oxide in the manganese oxide/titania catalyst is one or at least _two combinations _of MnO, Mn2O3 or _MnO2 . 22. The manganese oxide/titania catalyst according to claim 18, characterized in that the particle size of the manganese oxide/titania catalyst is 10-30 nm. 23. The use of the manganese oxide/titania catalyst according to claim 18, which is used in the field of FCC regeneration flue gas denitrification.