CN113651351A

CN113651351A - Samarium oxide and preparation and application thereof

Info

Publication number: CN113651351A
Application number: CN202110938526.4A
Authority: CN
Inventors: 余林; 高梓寒; 杨润农; 谢启星; 黄乐珩; 唐诗昌; 孙明; 程高
Original assignee: Guangdong University of Technology
Current assignee: Guangdong University of Technology
Priority date: 2021-08-16
Filing date: 2021-08-16
Publication date: 2021-11-16

Abstract

The invention provides a samarium oxide and its preparation and application. Specifically, the samarium oxide is obtained by mixing samarium salt, polyvinylpyrrolidone, C ₂ -C ₆ organic acid, water and ethylene glycol, performing hydrothermal reaction, cooling, centrifuging and calcining; The volume ratio of the diol is 8-12:50-80. The samarium oxide prepared by the present invention is spherical with uniform morphology, indicating that its crystallinity, dispersibility and thermal stability are good, it can be suitable for the carrier of SCR catalyst, and provides a new material source for denitration treatment.

Description

Samarium oxide and preparation and application thereof

Technical Field

The invention belongs to the technical field of denitration treatment. More particularly, to samarium oxide and preparation and application thereof.

Background

The rapid development of modern industry has led to an increasing environmental pollution problem, Nitrogen Oxides (NO)_x) As one of the main atmospheric pollutants, the environment problems of haze, acid rain, photochemical smog, ozone layer cavities and the like can be caused, the respiratory system of the human body can be greatly damaged, and the human health is seriously influenced. One of the most effective and widely used treatment technologies at present is Selective Catalytic Reduction (SCR), which converts NO over a catalyst_xReduction to N₂. The existing most common selective catalytic reduction catalyst is a vanadium-based catalyst, the working temperature of the vanadium-based catalyst generally needs to reach 300-400 ℃, but for coal consumption industries such as metallurgy, steel, petrifaction and cement, the tail gas of a coal-fired steam boiler is generally only 180-220 ℃, so that in order to meet the working temperature of the vanadium-based catalyst, a large-amplitude temperature rise is needed for reaction, and the denitration cost is greatly increased; the other common selective catalytic reduction catalyst is a molecular sieve catalyst which has good low-temperature activity and wide temperature window, but has poor thermal stability, and is easy to collapse under the action of high-temperature water vapor and lose reaction activity.

China is a big rare earth country, and elements such as cerium, zirconium, lanthanum and samarium in rare earth elements have been proved to have better denitration performance and good thermal stability, so that the preparation of the rare earth elements into catalyst carriers gradually becomes a hotspot of current denitration treatment research, for example, the applicant's earlier patent CN105948098B provides a preparation method of spherical lanthanum oxide, specifically, lanthanum salt and a plurality of substances are subjected to hydrothermal reaction, and then are cooled and centrifuged to obtain the spherical lanthanum oxide, but the inventor of the application adopts the method to prepare samarium oxide, and finds that an X-ray diffraction pattern has a plurality of miscellaneous peaks, and cannot prepare a target product, thereby indicating that the method of the patent CN105948098B is not suitable for preparing samarium oxide.

Disclosure of Invention

Aiming at the defects of the existing selective catalytic reduction catalyst, the invention provides samarium oxide, preparation and application thereof, and provides a novel SCR catalyst carrier for denitration treatment.

The invention aims to provide a preparation method of samarium oxide.

The second purpose of the invention is to provide the samarium oxide prepared by the method.

The third purpose of the invention is to provide the application of the samarium oxide in the preparation or the application of the samarium oxide as a selective catalytic reduction catalyst carrier.

The above purpose of the invention is realized by the following technical scheme:

the invention provides a preparation method of samarium oxide, and concretely relates to samarium salt, polyvinylpyrrolidone and C₂～C₆Mixing organic acid, water and ethylene glycol, carrying out hydrothermal reaction, cooling, centrifuging and calcining to obtain the samarium oxide;

wherein the volume ratio of the water to the glycol is 8-12: 50-80 parts.

Most preferably, the volume ratio of water to glycol is 12: 50, see example 1.

According to the invention, from the angle of the appearance of the samarium oxide, the preparation method of the samarium oxide is subjected to targeted research, the interaction of various raw materials is specifically researched, the variety and the dosage of each raw material are controlled through a large amount of experimental summary, the process is simple, the consumption is low, the efficiency is high, the prepared samarium oxide is spherical with uniform appearance, and the crystallinity, the dispersibility and the thermal stability are good, so that the samarium oxide can be used as an excellent SCR catalyst carrier.

Polyvinylpyrrolidone (PVP) and C₂～C₆The organic acid plays a vital role in regulating and controlling the appearance of the samarium oxide, and PVP (polyvinyl pyrrolidone) in the organic acid is adsorbed on the surface of the samarium oxide, so that the size of the particle size is limited, and the adhesion among spherical particles of the samarium oxide is prevented; c₂～C₆Organic acids due to the presence of a carboxylic acidRadicals and alkyl radicals, the carboxyl groups of which may be substituted with Sm³⁺Coordination and alkyl can modify samarium oxide nanoparticles and influence the interaction among the nanoparticles, thereby playing a role in regulating and controlling the morphology of the samarium oxide and being beneficial to the formation of the spherical morphology of the samarium oxide. The ethylene glycol can generate stronger coordination with samarium, the growth of nanocrystalline is controlled in the synthesis stage, in addition, the high viscosity characteristic of the ethylene glycol can reduce the nucleation and growth rate of the samarium oxide, so that the prepared samarium oxide has more uniform and regular appearance, a spherical secondary structure with lower surface energy is formed, and the thermal stability is high. The viscosity is adjusted by adding water, and the spherical particle samarium oxide is prevented from being adhered.

Preferably, the samarium salt is Sm (NO)₃)₃·6H₂O or SmCl₃·6H₂O。

Most preferably, the samarium salt is Sm (NO)₃)₃·6H₂See example 1.

Preferably, the polyvinylpyrrolidone comprises polyvinylpyrrolidone k 30.

Preferably, said C₂～C₆The organic acid comprises one or more of glacial acetic acid, propionic acid, n-butyric acid or n-caproic acid.

Most preferably, said C₂～C₆The organic acid is propionic acid, see example 1.

Preferably, the samarium salt, polyvinylpyrrolidone, C₂～C₆The dosage ratio of the organic acid to the water is 1-20 mmol: 0.05-0.07 mmol: 0.5-4 mL: 8-12 mL.

Most preferably, the samarium salt, polyvinylpyrrolidone, C₂～C₆The dosage ratio of the organic acid to the water is 17 mmol: 0.06 mmol: 2mL of: 12mL, see example 1.

Preferably, the calcination is carried out at 800-1200 ℃ for 2-4 h.

When the calcining temperature is too low, samarium oxide cannot be formed; when the temperature is too high, the shape of the samarium oxide can collapse, the whole samarium oxide is condensed into a solid sphere, the specific surface area is too small, and the samarium oxide can not be used as a selective catalytic reduction catalyst carrier.

Most preferably, the calcination is at 800 ℃ for 2h, see example 1.

Preferably, the calcination is carried out in an air atmosphere.

Further preferably, the temperature rise rate of the calcination is 1-5 ℃/min.

Most preferably, the temperature ramp rate for the calcination is 3 ℃/min, see example 1.

Preferably, stirring is further carried out during the mixing, and the stirring time is 5-60 min.

Most preferably, the stirring time is 30min, see example 1.

Preferably, the hydrothermal reaction is carried out for 1-16 h at 160-240 ℃.

Most preferably, the hydrothermal reaction is a hydrothermal reaction at 190 ℃ for 9h, see example 1.

Preferably, the centrifugation is performed for 2-8 min at the rotating speed of 7500-8500 r/min.

Most preferably, the centrifugation is at 8000r/min for 5min, see example 1.

The cooling and centrifuging operations of the invention have no special requirements and can be carried out according to the conventional technology in the field.

The invention also provides the samarium oxide prepared by the method.

Preferably, the particle size of the samarium oxide is 100-300 nm.

The samarium oxide prepared by the method is spherical with uniform appearance, so that the samarium oxide has better crystallinity, dispersity and thermal stability and can be suitable for a carrier of an SCR (selective catalytic reduction) catalyst, and therefore, the samarium oxide can be applied to preparation or serving as a carrier of a selective catalytic reduction catalyst within the protection range of the invention.

The invention has the following beneficial effects:

1. the samarium oxide prepared by the method is spherical with uniform appearance, so that the samarium oxide is better in crystallinity, dispersity and thermal stability, can be suitable for a carrier of an SCR (selective catalytic reduction) catalyst, and provides a new material source for denitration treatment.

2. The preparation method has the advantages of simple operation, low consumption, high efficiency, stable product and high repeatability, and is beneficial to industrial production.

Drawings

FIG. 1 is an X-ray diffraction pattern of the product of example 1.

FIG. 2 is an X-ray diffraction pattern of the products of comparative examples 8 to 9.

FIG. 3 is an SEM micrograph of the product of example 1

FIG. 4 is an SEM micrograph of the product of comparative example 1.

FIG. 5 is an SEM micrograph of the product of comparative example 3.

FIG. 6 is an SEM micrograph of the product of comparative example 4.

FIG. 7 is an SEM micrograph of the product of comparative example 6.

FIG. 8 is an SEM micrograph of the product of comparative example 7.

FIG. 9 shows the results of the activity test of the product of example 1.

Detailed Description

The invention is further described with reference to the drawings and the following detailed description, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Unless otherwise indicated, reagents and materials used in the following examples are commercially available.

EXAMPLE 1 preparation of samarium oxide

S1, dissolving 0.06mmol of polyvinylpyrrolidone k30(PVPk30, molecular weight M is 58000) in a mixed solution of 50mL of ethylene glycol and 12mL of deionized water, and adding 17mmol of Sm (NO)₃)₃·6H₂O and 2mL of propionic acid, and fully stirring for 30 min;

s2, transferring the solution into a 100mL polytetrafluoroethylene lining, putting the lining into a stainless steel reaction kettle, and heating the lining for 9 hours at 190 ℃;

s3, after cooling to room temperature, centrifuging at a rotating speed of 8000r/min for 5min to obtain a precipitate, washing with deionized water and ethanol for 3 times alternately, and then drying at 60 ℃ for 12 h; and grinding the dried product into fine powder by using a mortar, calcining the fine powder for 2h at 800 ℃ in the air atmosphere, and heating at the rate of 3 ℃/min to obtain the samarium oxide.

EXAMPLE 2 preparation of samarium oxide

S1, dissolving 0.05mmol of polyvinylpyrrolidone k30(PVPk30, molecular weight M is 58000) in a mixed solution of 80mL of ethylene glycol and 8mL of deionized water, and adding 20mmol of SmCl₃·6H₂O and 0.5mL of glacial acetic acid, and fully stirring for 30 min;

s2, transferring the solution into a 100mL polytetrafluoroethylene lining, putting the lining into a stainless steel reaction kettle, and carrying out hydrothermal treatment at 190 ℃ for 8 hours;

s3, after cooling to room temperature, centrifuging at a rotating speed of 8000r/min for 5min to obtain a precipitate, washing with deionized water and ethanol for 3 times alternately, and then drying at 60 ℃ for 12 h; and grinding the dried product into fine powder by using a mortar, calcining the fine powder for 2 hours at 800 ℃ in the air atmosphere at the heating rate of 1 ℃/min, and obtaining the samarium oxide.

EXAMPLE 3 preparation of samarium oxide

S1, dissolving 0.07mmol of polyvinylpyrrolidone k30(PVPk30, molecular weight M is 58000) in a mixed solution of 50mL of ethylene glycol and 12mL of deionized water, and adding 1mmol of Sm (NO)₃)₃·6H₂O and 4mL of hexanoic acid, and fully stirring for 60 min;

s2, transferring the solution into a 100mL polytetrafluoroethylene lining, putting the lining into a stainless steel reaction kettle, and carrying out hydrothermal treatment at 240 ℃ for 16 h;

s3, after cooling to room temperature, centrifuging for 8min at the rotating speed of 7500r/min to obtain a precipitate, washing for 3 times by using deionized water and ethanol alternately, and then drying for 12h at 60 ℃; and grinding the dried product into fine powder by using a mortar, calcining the fine powder for 4 hours at 1200 ℃ in the air atmosphere, and heating at the rate of 5 ℃/min to obtain the samarium oxide.

EXAMPLE 4 preparation of samarium oxide

S1, dissolving 0.06mmol of polyvinylpyrrolidone k30(PVPk30, molecular weight M is 58000) in a mixed solution of 60mL of ethylene glycol and 10mL of deionized water, and adding 15mmol of Sm (NO)₃)₃·6H₂O and 1mL of n-butyric acid, and fully stirring for 5 min;

s2, transferring the solution into a 100mL polytetrafluoroethylene lining, putting the lining into a stainless steel reaction kettle, and carrying out hydrothermal treatment at 160 ℃ for 1 h;

s3, after cooling to room temperature, centrifuging at the rotating speed of 8500r/min for 2min to obtain a precipitate, washing with deionized water and ethanol for 3 times alternately, and then drying at 60 ℃ for 12 h; and grinding the dried product into fine powder by using a mortar, calcining the fine powder for 2h at 800 ℃ in the air atmosphere, and heating at the rate of 3 ℃/min to obtain the samarium oxide.

Comparative example 1

The preparation was identical to that of example 1, except that the amount of ethylene glycol used was 40 mL.

Comparative example 2

The preparation was identical to that of example 1, except that the amount of ethylene glycol used was 90 mL.

Comparative example 3

The same preparation as in example 1 except that Sm (NO) is used₃)₃·6H₂The amount of O used was 25 mmol.

Comparative example 4

The preparation of example 1 is identical, except that the polyvinylpyrrolidone k30 is not added.

Comparative example 5

The preparation of example 1 was repeated, except that 0.1mmol of polyvinylpyrrolidone k30 was used.

Comparative example 6

The preparation was identical to that of example 1, except that the propionic acid was used in an amount of 0.05 mL.

Comparative example 7

The preparation was the same as in example 1, except that the amount of propionic acid used was 5 mL.

Comparative example 8

The preparation of example 1 is identical, except that the calcination is carried out at 600 ℃ for 5 h.

Comparative example 9

The preparation of example 1 is identical, except that the calcination is carried out at 400 ℃ for 4 h.

Comparative example 10

First, experiment method

The method of patent CN105948098B is adopted to prepare samarium oxide:

s1, weighing Sm (NO)₃)₃·6H₂Dissolving O in a mixed solution of deionized water and ethylene glycol, stirring until the O is completely dissolved, adding polyvinylpyrrolidone k30(PVPk30, molecular weight M is 58000), stirring for 1h to obtain a transparent and clear solution, adding propionic acid, and continuing stirring for 0.5 h;

s2, transferring the transparent and clear mixed solution obtained in the step S1 into a 100ml polytetrafluoroethylene lining, putting the mixture into a stainless steel reaction kettle, and reacting for 200min at 200 ℃;

s3, after the reaction kettle is cooled to the room temperature, centrifuging the product for 5min at the rotating speed of 10000r/min to obtain a precipitate, alternately washing the precipitate for 3 times by using deionized water and ethanol, and then drying the precipitate for 12h at 80 ℃ to obtain the samarium oxide.

Second, performance test

XRD test of the product obtained in the comparative example 10 shows that the X-ray diffraction pattern of the product has a plurality of mixed peaks and has no analytical significance, which indicates that the method of the patent CN105948098B is not suitable for preparing samarium oxide.

Experimental examples samarium oxide Performance testing

First, XRD test

XRD tests were carried out on the products obtained in examples 1 to 4 and comparative examples 1 to 9, respectively.

The X-ray diffraction pattern of example 1 is shown in figure 1, and the X-ray diffraction patterns of examples 2-4 and comparative examples 1-7 are similar to that of figure 1, which shows that the products of examples 1-4 and comparative examples 1-7 are samarium oxide.

The X-ray diffraction patterns of the comparative examples 8 to 9 are shown in fig. 2, and analysis shows that the product obtained under the condition of calcination at 600 ℃ (comparative example 8) is samarium carbonate, and the product obtained under the condition of calcination at 400 ℃ (comparative example 9) is poor in crystallinity and cannot be identified. Comparing the X-ray diffraction patterns of the comparative examples 8 to 9 with the X-ray diffraction pattern under the condition of calcination at 800 ℃ (example 1), the calcination operation is indispensable for the preparation of samarium oxide, the temperature setting is also crucial, and if the temperature is lower than 800 ℃, the samarium oxide cannot be prepared.

Second, SEM scanning electron microscope test

SEM scanning electron microscope tests were performed on the products obtained in examples 1 to 4 and comparative examples 1 to 7, respectively.

Wherein, the SEM electron micrograph of example 1 is shown in fig. 3, and the SEM electron micrographs of examples 2 to 4 are similar to fig. 1, and it can be seen from the analysis that the samaria obtained in examples 1 to 4 are spherical with uniform morphology and particle size of 100 to 300nm, which shows that the samaria obtained by the present invention has good crystallinity, dispersibility and thermal stability.

The SEM scanning electron micrograph of comparative example 1 is shown in FIG. 4, and that of comparative example 2 is similar to that of comparative example 1; the SEM micrograph of comparative example 3 is shown in FIG. 5; the SEM micrograph of comparative example 4 is shown in fig. 6, and that of comparative example 5 is similar to comparative example 4; the SEM micrograph of comparative example 6 is shown in fig. 7; the SEM micrograph of comparative example 7 is shown in fig. 8. As can be seen from figures 4-8, the product has irregular shape and agglomeration phenomenon, which indicates that the samarium oxide prepared by the method has poor crystallinity, dispersibility and thermal stability.

Application examples samarium oxide denitration Effect

First, experiment method

The samarium oxide prepared in examples 1 to 4 was subjected to Mn loading and performance measurement by the following methods, respectively.

(1) Loading of Mn:

adding 0.92g of samarium oxide into a beaker, adding 1.5ml of absolute ethyl alcohol and 0.3343g of manganese acetylacetonate, uniformly mixing, oscillating for 5min by using an ultrasonic cleaner, stirring until the solution is viscous paste, drying overnight, and grinding into powder; the powder is put into a muffle furnace to be calcined for 2h at the temperature of 400 ℃, the heating rate is 3 ℃/min, and the composite catalyst Mn/Sm is prepared₂O₃。

(2) And (3) performance measurement:

0.2g of 40-60 mesh composite catalyst Mn/Sm is taken₂O₃The mixture was put into a quartz tube having an inner diameter of 8mm and then put into a fixed bed reactor. The activity test conditions were set as: [ NO ]]＝[NH₃]＝700ppm，[O2]6.5%, argon as the balance gas. The total flow of the gas is 700mL/min, the test temperature is 30-450 ℃, the heating rate is 3 ℃/min, and the space velocity is 280000h^-1。

Second, experimental results

The activity test result of the embodiment 1 is shown in fig. 9, the activity test result of the embodiments 2 to 4 is similar to that of fig. 9, and it can be seen from fig. 9 that the denitration rate of the samarium oxide at the temperature of 250 to 400 ℃ can reach more than 80%, and even can approach 100% at about 310 ℃, which indicates that the samarium oxide prepared by the invention can be used for preparing a carrier of a selective catalytic reduction catalyst, and provides a new material source for denitration treatment.

In conclusion, the samarium oxide prepared by the method is spherical with uniform appearance, so that the samarium oxide is better in crystallinity, dispersity and thermal stability, can be suitable for a carrier of an SCR (selective catalytic reduction) catalyst, and provides a new material source for denitration treatment.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. a preparation method of samarium oxide, is characterized in that, samarium salt, polyvinylpyrrolidone, C ₂ ～C ₆ organic acid, water and ethylene glycol are mixed, carry out hydrothermal reaction, cooling, centrifugation, calcination, obtain the obtained said samarium oxide;

Wherein, the volume ratio of the water and ethylene glycol is 8-12:50-80.

2 . The method according to claim 1 , wherein the samarium salt is Sm(NO ₃ ) ₃ ·6H ₂ O or SmCl ₃ ·6H ₂ O. 3 .

3. The method according to claim 1, wherein the polyvinylpyrrolidone comprises polyvinylpyrrolidone k30.

The method according to claim 1, wherein the C2 _- _C6 organic acid comprises one or more of glacial acetic acid, propionic acid, n-butyric acid or n-hexanoic acid.

5. The method according to claim 1, wherein the consumption ratio of the samarium salt, polyvinylpyrrolidone, C2 _- _C6 organic acid and water is 1-20 mmol: 0.05-0.07 mmol: 0.5-4 mL: 8 ~12mL.

6 . The method according to claim 1 , wherein the calcination is calcined at 800-1200° C. for 2-4 hours. 7 .

7 . The method according to claim 1 , wherein the hydrothermal reaction is a hydrothermal reaction at 160-240° C. for 1-16 h. 8 .

8. Samarium oxide prepared by any one of claims 1 to 7.

9 . The samarium oxide according to claim 8 , wherein the particle size of the samarium oxide is 100-300 nm. 10 .

10. Use of the samarium oxide of claim 8 or 9 in preparation or as a carrier for a selective catalytic reduction catalyst.