CN105664910A

CN105664910A - Preparation method of doped CeO2-TiO2 catalyst

Info

Publication number: CN105664910A
Application number: CN201610117933.8A
Authority: CN
Inventors: 钟秦; 朱利; 张舒乐; 曾毅清
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2016-03-02
Filing date: 2016-03-02
Publication date: 2016-06-15

Abstract

The invention discloses a preparation method of a doped CeO2-TiO2 catalyst. The preparation method comprises the following steps: adding cerous nitrate into a container with absolute ethyl alcohol, stirring continuously, and slowly adding tetrabutyl titanate and continuously stirring after cerous nitrate is dissolved completely, thereby obtaining a solution A; slowly adding a mixed solution of deionized water and glacial acetic acid into absolute ethyl alcohol and stirring to obtain a solution B; and slowly dropwise adding the solution B into the solution A and stirring continuously, ageing obtained sol in a drying oven, drying obtained gel, and calcining, thereby obtaining the doped CeO2-TiO2 catalyst. Cerium species of the doped CeO2-TiO2 catalyst are doped into titanium dioxide lattices, and compared with a CeO2/TiO2 catalyst prepared by an ordinary supported preparation method, the doped CeO2-TiO2 catalyst can generate more Ce-square-Ti type oxygen vacancies, so that the efficiency of oxidizing NO in the presence of the catalyst to form nitro species, intermediate products of NH3-SCR reactions is improved, and the denitration efficiency of the CeO2-TiO2 catalyst is improved.

Description

The preparation method of doping type cerium titanium catalyst

Technical field

The present invention relates to the preparation method of a kind of catalyzer, particularly the preparation method of the titanium dioxide low-temperature denitration catalyst of a kind of cerium species doping, belongs to inorganic catalytic field.

Background technology

Denitrating catalyst is NH₃The key of-SCR technology. Current widely used commercial catalyst is V₂O₅-WO₃/TiO₂Catalyzer, its active temperature windows is 300 DEG C ~ 400 DEG C, and this catalyzer is widely used because of its good catalytic activity and thermostability. But, catalytic component based on vanadium active temperature windows is narrower, can not meet the use under special operation condition. And, V under high temperature₂O₅Can by the SO in flue gas₂It is oxidized to SO₃, cause secondary pollution. In addition, environment and human body are easily caused comparatively serious infringement after discarding by vanadium series catalyst. Therefore V₂O₅-WO₃/TiO₂The further genralrlization of catalyzer uses and is restricted. Therefore effect wider for active temperature windows, low-temperature catalyzed exploitation better, Environmentally-friedenitration denitration catalyst seems very necessary. Oxidation of interim metal catalyzer, precious metal element oxide catalyst, rare earth oxide and molecular sieve catalyst are subject to the extensive research of scholar.

Research shows, owing to rare-earth oxide has the feature such as 4f track and lanthanide contraction of underfill electronics, it can show special performance. The existence of rare earth species can effectively change the acid-basicity of catalyst surface, modifies catalytic active center, improves the storage of catalyzer/release oxygen ability, strengthen its structural stability and improve the dispersity etc. of active ingredient^]. Cerium dioxide (CeO₂) as the most important components in RE treatment steel, owing to there is excellent redox property and storing up/release oxygen ability and good Ce preferably³⁺/Ce⁴⁺Switching capability, at NH₃-SCR has a wide range of applications in reacting. CeO₂Can be used as the carrier of catalyzer, auxiliary agent and active ingredient.

CeO₂Showing good catalytic activity on carrier as active constituent loading, be therefore subject to the extensive concern of researchist, different cerium species content and different calcining temperature have been studied by researchist. Research shows that this catalyzer just can reach the catalytic activity of more than 95% when 300 DEG C, but its low-temperature zone catalytic effect is unsatisfactory.Also there is researchist by introducing auxiliary agent WO₃Promote the activity of catalyzer, but therefore just improve the cost of integer catalyzer.

Summary of the invention

It is an object of the invention to provide that a kind of production cost is low, low-temperature denitration superior activity and the wider cerium species doped Ti O of active temperature windows₂The preparation method of denitrating catalyst.

It is an object of the invention to be achieved through the following technical solutions: the preparation method of a kind of doping type cerium titanium catalyst, comprises the following steps:

Step 1: add the cerous nitrate of certain stoichiometry to the container filling dehydrated alcohol and constantly stir, treat

After dissolving completely, more slowly add tetrabutyl titanate and constantly stir, obtain solution A;

Step 2: the mixed solution of deionized water and Glacial acetic acid is slowly added in dehydrated alcohol and stir, obtain solution B;

Step 3: solution B is slowly added drop-wise in solution A and constantly stirs, then the colloidal sol obtained is placed in baking oven ageing, by gained gel drying, and calcines, obtain the CeO of described doping type₂-TiO₂Catalyzer.

In step 1, described ethanol and the volume ratio of tetrabutyl titanate are 2 ~ 6; Elemental mole ratios [Ce]/[Ti]=5% ~ 30% in solution A; Churning time is 25 ~ 50min; Whipping temp is 20 ~ 40 DEG C.

In step 2, described Glacial acetic acid and the volume ratio of tetrabutyl titanate are 0.2 ~ 0.5; Described deionized water and the volume ratio of Glacial acetic acid are 0.5 ~ 2; Churning time is 25 ~ 50min; Whipping temp is 20 ~ 40 DEG C.

In step 3, described churning time is 40 ~ 120min; Described whipping temp is 20 ~ 50 DEG C; Described ageing temperature is 20 ~ 60 DEG C; Described digestion time is 1 ~ 7 day; The drying temperature of described gel is 80 ~ 150 DEG C; Described time of drying is 8 ~ 15h; Described calcining temperature is 400 ~ 600 DEG C; Described calcination time is 2 ~ 4h.

The present invention compared with prior art its significant advantage be:

(1) the present invention has prepared the titanium deoxide catalyst of cerium species doping by being easy to the sol-gel method of operation, and these doping type catalyst surface cerium species and titanium species have stronger interaction, and produce more Ce--Ti type Lacking oxygen;

(2) only Ce--Ti type Lacking oxygen could effectively adsorb and activate oxygen, produce more superoxide radical, so that the reaction of superoxide radical and NO is more rapid, produce more SCR intermediate product nitro class species, thus promote the carrying out of reaction;

(3) using doping type catalyzer, the usage quantity reaching identical efficient catalytic effect Ce species obviously reduces, thus reduces the production cost of catalyzer so that it is easily accepted by factory;

(4) adopt cerium as active ingredient, decrease vanadium species discarded after to the toxic action of environment so that catalyzer is environmental protection more;

(5), after adopting this preparation method so that catalyst low-temperature activity significantly improves, when 240 DEG C, catalyzer just can reach close to 100% denitration efficiency so that it is active temperature windows has widened 150 DEG C to low temperature.

Accompanying drawing explanation

Fig. 1 is CeO prepared by the embodiment of the present invention₂-TiO₂The XRD spectra of catalyzer.

Fig. 2 is the denitration activity comparison diagram of method for preparing catalyst of the present invention with conventional preparation method.

Fig. 3 is CeO prepared by various embodiments of the present invention₂-TiO₂The catalytic denitration activity figure of catalyzer.

Embodiment

Below in conjunction with embodiment, the present invention is further elaborated.

Embodiment one:

CeO prepared in accordance with the present invention₂-TiO₂Denitrating catalyst, wherein the elemental mole ratios of Ce/Ti is that 0.05(represents for 5Ce-Ti).

Add 1.27g cerous nitrate to the beaker filling 80ml dehydrated alcohol and constantly stir, until completely dissolved, more slowly add 20ml tetrabutyl titanate and constantly stir 30min, obtain solution A. 8ml deionized water and 8ml glacial acetic acid mixed solution are slowly added in 20ml dehydrated alcohol and stirs, obtain solution B. Solution B is slowly added solution A and constantly stirs 2h, just can obtain colloidal sol, then this colloidal sol is placed in 25 DEG C of baking oven ageings 2 ~ 3 days, just gel state can be obtained, gained gel is placed in the dry 12h of 105 DEG C of baking ovens, at 500 DEG C of temperature lower calcination 3h, just can obtain 5Ce-Ti-500 catalyzer.

Embodiment two:

CeO prepared in accordance with the present invention₂-TiO₂Denitrating catalyst, wherein the elemental mole ratios of Ce/Ti is that 0.75(represents for 7.5Ce-Ti).

Add 1.91g cerous nitrate to the beaker filling 80ml dehydrated alcohol and constantly stir, until completely dissolved, more slowly add 20ml tetrabutyl titanate and constantly stir 30min, obtain solution A. 8ml deionized water and 8ml glacial acetic acid mixed solution are slowly added in 20ml dehydrated alcohol and stirs, obtain solution B. Solution B is slowly added solution A and constantly stirs 2h, just can obtain colloidal sol, then this colloidal sol is placed in 25 DEG C of baking oven ageings 2 ~ 3 days, just gel state can be obtained, gained gel is placed in the dry 12h of 105 DEG C of baking ovens, at 500 DEG C of temperature lower calcination 3h, just can obtain 7.5Ce-Ti-500 catalyzer.

Embodiment three:

CeO prepared in accordance with the present invention₂-TiO₂Denitrating catalyst, wherein the elemental mole ratios of Ce/Ti is that 0.10(represents for 10Ce-Ti).

Add 2.54g cerous nitrate to the beaker filling 80ml dehydrated alcohol and constantly stir, until completely dissolved, more slowly add 20ml tetrabutyl titanate and constantly stir 30min, obtain solution A. 8ml deionized water and 8ml glacial acetic acid mixed solution are slowly added in 20ml dehydrated alcohol and stirs, obtain solution B. Solution B is slowly added solution A and constantly stirs 2h, just can obtain colloidal sol, then this colloidal sol is placed in 25 DEG C of baking oven ageings 2 ~ 3 days, just gel state can be obtained, gained gel is placed in the dry 12h of 105 DEG C of baking ovens, at 500 DEG C of temperature lower calcination 3h, just can obtain 10Ce-Ti-500 catalyzer.

Embodiment four:

Comparative sample CeO₂/TiO₂The preparation of denitrating catalyst, wherein the elemental mole ratios of Ce/Ti is that 0.10(represents for 10Ce/Ti).

Add 22ml tetrabutyl titanate to filling in the crucible of 50ml dehydrated alcohol, stir 30min, then, add the methyl ethyl diketone of 13ml, continue to stir 2h; Gained solution is carried out 60 DEG C of water-bath 6h, dries 6h, and calcine 3h at 500 DEG C, just obtain TiO for 120 DEG C₂Carrier.

Then, to filling, 50ml deionized water adds above-mentioned TiO₂Powder 3g, constantly stirs 30min, adds cerous nitrate 0.757g, and continues to stir 2h. Gained solution is carried out 60 DEG C of water-bath 6h, dries 6h, and calcine 3h at 500 DEG C, just obtain 10Ce/Ti-500 catalyzer for 120 DEG C.

Embodiment five:

Catalyzer prepared by above-described embodiment one, example two, example three and embodiment four is carried out XRD test, and result is as shown in Figure 1.

Conventional load catalyzer prepared by the doped catalyst prepare above-described embodiment three and embodiment four carries out denitration activity evaluation, and result is as shown in Figure 2.

Doped catalyst prepared by above-described embodiment one, embodiment two and embodiment three is carried out denitration activity evaluation, and result is as shown in Figure 3.

The reaction conditions carrying out catalytic denitration is: NO concentration 500ppm, NH₃600ppm, 5%O₂, N₂Doing carrier gas, gas flow is 150ml/min, and temperature of reaction is 120 ~ 270 DEG C.

Claims

1. the preparation method of a doping type cerium titanium catalyst, it is characterised in that, comprise the following steps:

Step 1: add cerous nitrate to the container filling dehydrated alcohol, constantly stir, until completely dissolved, more slowly adds tetrabutyl titanate and constantly stirs, obtain solution A;

2. the preparation method of doping type cerium titanium catalyst as claimed in claim 1, it is characterised in that, in step 1, described ethanol and the volume ratio of tetrabutyl titanate are 2 ~ 6; Elemental mole ratios [Ce]/[Ti]=5% ~ 30% in solution A; Churning time is 25 ~ 50min; Whipping temp is 20 ~ 40 DEG C.

3. the preparation method of doping type cerium titanium catalyst as claimed in claim 1, it is characterised in that, in step 2, described Glacial acetic acid and the volume ratio of tetrabutyl titanate are 0.2 ~ 0.5; Described deionized water and the volume ratio of Glacial acetic acid are 0.5 ~ 2; Churning time is 25 ~ 50min; Whipping temp is 20 ~ 40 DEG C.

4. the preparation method of doping type cerium titanium catalyst as claimed in claim 1, it is characterised in that, in step 3, described churning time is 40 ~ 120min; Described whipping temp is 20 ~ 50 DEG C; Described ageing temperature is 20 ~ 60 DEG C; Described digestion time is 1 ~ 7 day; The drying temperature of described gel is 80 ~ 150 DEG C; Described time of drying is 8 ~ 15h; Described calcining temperature is 400 ~ 600 DEG C; Described calcination time is 2 ~ 4h.