CN113198451A - Monolithic catalyst, preparation method and application - Google Patents

Monolithic catalyst, preparation method and application Download PDF

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CN113198451A
CN113198451A CN202110538751.9A CN202110538751A CN113198451A CN 113198451 A CN113198451 A CN 113198451A CN 202110538751 A CN202110538751 A CN 202110538751A CN 113198451 A CN113198451 A CN 113198451A
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dpf
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catalyst
monolithic catalyst
preparing
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CN113198451B (en
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田蒙奎
赵冰
谭义凤
李帆
李茂坤
陈玟霖
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Guizhou University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/105—General auxiliary catalysts, e.g. upstream or downstream of the main catalyst
    • F01N3/106—Auxiliary oxidation catalysts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y02A50/2351—Atmospheric particulate matter [PM], e.g. carbon smoke microparticles, smog, aerosol particles, dust

Abstract

The invention discloses an integral catalyst, a preparation method and application thereof. The invention provides a method for preparing Ce by a sol-gel method1‑ xTixO2The method of the composite oxide, then the composite oxide is used as a carrier, and an impregnation method is adopted to load alkali metal to obtain M/Ce1‑ xTixO2Catalyst, finally coating the catalyst on DPF carrier to obtain M/Ce1‑xTixO2The DPF monolithic catalyst is applied to the CDPF field, has low price compared with a noble metal catalyst, and has the characteristics of strong catalytic oxidation effect, high oxidation efficiency and low loading capacity, 8 percent of Cs/Ce0.92Ti0.08O2The activity of the catalyst is highest, wherein TiAt 319 ℃ T90At 421 deg.C, large amplitudeThe soot combustion rate is improved, and 8% Cs/Ce is obtained by coating the soot on a DPF carrier0.92Ti0.08O2Monolithic catalyst for DPF, results show Ce0.92Ti0.08O2The loading of 2.5 wt% DPF, T, achieves the lowest loading at high efficiency in this experimental rangeiAt 323 ℃ T90491 ℃.

Description

Monolithic catalyst, preparation method and application
Technical Field
The invention relates to an integral catalyst, in particular to an integral catalyst, a preparation method and application thereof.
Background
In recent years, haze affects parts of areas in China all the year round, and harmful substances PM (carbon smoke particles) in tail gas of diesel vehicles are one of main reasons for causing haze weather, so that the health of human beings is seriously affected. A highly efficient diesel exhaust Particulate trap dpf (diesel Particulate filter) is indispensable. The structure of the filter screen is provided with a plurality of parallel channels along the axial direction, and the parallel channels are staggered to block holes to form a filter screen structure which can only allow gas to pass through. Therefore, when diesel vehicle tail gas passes through DPF, the separation that dams of particulate matter is realized through the surface screening principle under the pressure drive, and the great PM particulate matter of volume is just caught and is depositd in filter wall and inside the porous medium structure, and DPF is in the operation in-process, and the particulate matter of catching can block up the filter and cause exhaust back pressure to rise thereby to lead to the purification efficiency step-down or even filter damage, consequently the soot particulate matter that dams at the wall is removed through the mode of oxidation burning, and this is exactly the regeneration process of DPF. The temperature of the tail gas of the diesel vehicle is 150 ℃ and 500 ℃, and the soot particles can be combusted only when the temperature reaches above 600 ℃. Catalytic diesel particulate trap (CDPF) technology is required to remove soot at ambient diesel exhaust temperatures without the addition of external energy, and the core content of CDPF is the catalyst.
At present, the Ce-Ti material is mainly focused on energy and environmental problems such as photocatalysis, nitrogen oxide reduction and the like, is rarely applied to the field of carbon smoke oxidation, and has potential research value for catalyzing and oxidizing the carbon smoke.
In conclusion, the development of the integral catalyst with low cost, good activity, high efficiency and low loading capacity has important significance for eliminating the soot of the diesel vehicle.
Disclosure of Invention
The invention aims to provide an integral catalyst, a preparation method and application thereof. The invention provides a method for preparing Ce by a sol-gel method1-xTixO2The method of the composite oxide, then the composite oxide is used as a carrier, and an impregnation method is adopted to load alkali metal to obtain M/Ce1-xTixO2Catalyst, finally coating the catalyst on DPF carrier to obtain M/Ce1-xTixO2The DPF monolithic catalyst is applied to the CDPF field, has low price compared with a noble metal catalyst, and has the characteristics of strong catalytic oxidation effect, high oxidation efficiency and low loading capacity.
The technical scheme of the invention is as follows: a preparation method of a monolithic catalyst comprises the following steps:
(1) preparation of Ce by sol-gel method1-xTixO2Carrier:
dissolving 1-3g of solid cerium nitrate in 30mL of absolute ethyl alcohol according to the following proportion, and then adding 10mL of deionized water to obtain a product A; the chemical formula of the solid cerium nitrate is Ce (NO)3)2·6H2O；
Regulating the pH value of the product A with glacial acetic acid to make the pH value of the product A be 2.5-3.5 to obtain a product B;
thirdly, under the stirring state, dropwise adding butyl titanate into the product B, then heating in a water bath at 50-70 ℃, and stirring for reaction for 2-4h to obtain a reaction solution, namely a product C;
fourthly, performing ultrasonic cleaning on the cordierite-based diesel vehicle particulate matter catcher-DPF in water for 1.5 to 2.5 hours, and drying at 90 to 110 ℃ to obtain a D product;
fifthly, putting the product D into the product C, heating in water bath at 30-50 ℃, aging for 6-10h, and drying at 60-80 ℃ for 46-50h to obtain a product E;
sixthly, roasting the E product at the temperature of 400-600 ℃ to obtain Ce1-xTixO2The load is 1.25-3.75 wt% of integral catalyst of DPF, which is F product; and said Ce is1-xTixO2X is more than or equal to 0.07 and less than or equal to 0.09;
(2) impregnation method for preparing M/Ce1-xTixO2Catalyst:
adding F into alkali metal carbonate solution to control the active component load of carbonate solution to Ce1-xTixO26-10% of the carrier mass, ultrasonic treatment for 1.5-2.5h, drying at 70-90 ℃, then heating to 450-550 ℃ at the speed of 2-4 ℃/min, roasting, and keeping the temperature for 1.5-2.5h to obtain M/Ce1-xTixO2The metal of M is Cs, K or Na, and x is more than or equal to 0.07 and less than or equal to 0.09.
In the preparation method of the monolithic catalyst, in the step (i), 2g of solid cerium nitrate is dissolved in 30mL of absolute ethyl alcohol according to the following proportion, and then 10mL of deionized water is added.
In the preparation method of the monolithic catalyst, in the second step, glacial acetic acid is used for adjusting the pH value of the product A to enable the pH value of the product A to be 2.
In the preparation method of the monolithic catalyst, in the third step, the molar ratio of Ce to Ti is 1-x: and x, dropwise adding butyl titanate into the product B, heating in a water bath at 60 ℃, and stirring to react for 3 hours to obtain a reaction solution.
In the preparation method of the monolithic catalyst, in the step (IV), the cordierite-based diesel particulate filter-DPF is subjected to ultrasonic treatment in water for 2 hours and dried at 100 ℃.
In the preparation method of the monolithic catalyst, in the fifth step, the product D is put into the product C, is heated in a water bath at 40 ℃, is aged for 7 hours, and is dried for 48 hours at 70 ℃.
In the preparation method of the monolithic catalyst, in the step sixthly, the D product is roasted at the temperature of 500 ℃ to obtain Ce1- xTixO2The load is 2.5 wt% of DPF, and is E product; and said Ce is1-xTixO2Wherein x is 0.08.
In the aforementioned method for preparing the monolithic catalyst, in the step (c), the product E is added to the alkali metal carbonate solution, and the loading amount of the active component of the carbonate solution is controlled to Ce1-xTixO2Ultrasonic treatment for 2h, drying at 80 deg.C, heating to 500 deg.C at 3 deg.C/min, calcining, and maintaining for 2h to obtain M/Ce1-xTixO2Finished DPF.
In the above-mentioned preparation method of the monolithic catalyst, in the step (c), the alkali metal carbonate solution is Cs2CO3A solution; the M/Ce1-xTixO2In the DPF, the M metal is Cs, and x is 0.08.
The application of the monolithic catalyst is M/Ce prepared by the preparation method of the monolithic catalyst1- xTixO2The DPF integrated catalyst is used in a diesel vehicle tail gas DPF reaction system to convert carbon smoke particles into nontoxic and pollution-free CO2The reaction temperature is 310-420 ℃, and the total flow of the gas is controlled to be 400-550 mL/min.
Compared with the prior art, the invention has the following beneficial effects:
the invention adopts a simpler sol-gel method to prepare Ce1-xTixO2The composite oxide is used as a carrier, and an impregnation method is adopted to load alkali metal to obtain M/Ce1-xTixO2Catalyst, finally selecting the catalyst with the best activity to be coated on DPF carrier to obtain M/Ce1-xTixO2a/DPF monolithic catalyst.
The molar content of Ti is adjustable, wherein a certain amount of Ti is doped into CeO2Within the crystal, CeO is not changed2The Ce-O-Ti bond is formed under the condition of the structure, the fluorite structure of the catalyst filled with cubic gaps is reserved, and the ion mobility in the catalyst is enhanced, so that the activity of the catalyst is improved. Wherein Ce1-xTixO2The composite oxide is widely applied to the fields of photocatalysis and denitration, and the research on carbon smoke catalysis is less.
The results show that Ce0.92Ti0.08O2Ignition temperature T of catalyst oxidation sootiAt 343 ℃ and a temperature T at which 90% conversion occurs90458 ℃ lower than that of pure CeO2T ofi＝391℃，T90At 512 ℃. The catalytic activity is higher than that of the systems common in catalytic oxidation of soot, such as Ce0.92Ti0.08O2T of50(425 ℃) lower than Ce produced by Liu0.6Zr0.4O2T of catalyst50(460 ℃ C.), lower than Ce produced by Ve nkataswamy0.7Fe0.3O2T of catalyst50(512 ℃ C.). The alkali metal can improve the activity of the catalyst on the soot combustion, because the alkali metal in the carbonate can generate C-O-M, and the C-O-M reacts with the soot to generate CO2Then is reduced into C-M and oxidized into C-O-M, and the circulation is favorable for O in soot combustion2The efficient utilization of the water is realized.
The experimental result shows that the concentration of the C is 8 percent/Ce0.92Ti0.08O2The activity of the catalyst is highest, wherein TiAt 319 ℃ T90The temperature is 421 ℃, and the soot combustion rate is greatly improved. Finally, the catalyst with the best activity is selected to be 8% Cs/Ce0.92Ti0.08O2Coating on DPF carrier to obtain 8% Cs/Ce0.92Ti0.08O2Monolithic catalyst for DPF, results show Ce0.92Ti0.08O2The loading of DPF2.5 wt% achieves the lowest loading at high efficiency in this experimental range, where TiAt 323 ℃ T90491 ℃ because the DPF filter body has larger volume and is heated uniformly to a degree lower than that of the powdery catalyst, the overall soot combustion efficiency is reduced. But achieves near complete conversion of soot below 500 c compared to most other monolithic catalysts. T of monolithic catalyst 25Ag/Ce-A/DPF prepared by Valeria, for example90T of 20Cu/Ce-A/DPF at 580 deg.C90It was 600 ℃ and the weight of the catalyst and the ceramic carrier was 1g/0.5 g.
The invention relates to 8% Cs/Ce0.92Ti0.08O2The DPF monolithic catalyst has the advantages of low cost, simple method and high catalytic activity. Wherein Ce1-xTixO2The composite oxide is widely applied to the fields of photocatalysis and denitration, and the Ce of the invention1- xTixO2Of composite oxides on sootThe combustion is also highly effective.
In conclusion, the invention provides a sol-gel method for preparing Ce1-xTixO2The method of the composite oxide, then the composite oxide is used as a carrier, and an impregnation method is adopted to load alkali metal to obtain M/Ce1-xTixO2Catalyst, finally coating the catalyst on DPF carrier to obtain M/Ce1-xTixO2The DPF monolithic catalyst is applied to the CDPF field, has low price compared with a noble metal catalyst, and has the beneficial effects of strong catalytic oxidation effect, high oxidation efficiency and low loading capacity.
Drawings
FIG. 1 is Ce prepared in examples 1-3 of the present invention1-xTixO2Catalyzing CO in soot process2Graph of concentration (a) and soot conversion (b);
FIG. 2 shows M/Ce prepared in examples 4-6 of the present invention1-xTixO2M is Cs, K or Na, x is 0.08 and Ce0.92Ti0.08O2Catalyzing CO in soot process2Graph of concentration (a) and soot conversion (b);
FIG. 3 is a 8% Cs/Ce solution prepared according to examples 7-9 of the present invention1-xTixO2Catalyst for catalyzing CO in soot process by using monolithic catalyst of 0.08 x in DPF2Graph of concentration (a) and soot conversion (b);
FIG. 4 shows catalyst Ce prepared by the present invention0.92Ti0.08O2(a) And 8% Cs/Ce0.92Ti0.08O2(b) A TEM image of (B);
FIG. 5 shows DPF carrier and the monolithic catalyst 8% Cs/Ce prepared by the invention0.92Ti0.08O2SEM picture of/DPF-2; wherein [ DPF (a) ], 8% Cs/Ce0.92Ti0.08O2/DPF-2(b,c)】。
Detailed Description
The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.
Example 1: ce0.91Ti0.09O2Preparing a catalyst;
2g of solid cerium nitrate (Ce (NO)3)2·6H2O) is dissolved in 30mL of absolute ethyl alcohol, 10mL of deionized water is added, the pH value of the solution is adjusted to 3 by glacial acetic acid, 0.1568mL of butyl titanate is added dropwise under the stirring state, the solution is heated to 60 ℃ in a water bath, the stirring reaction is continued for 3h to obtain reaction liquid, the reaction liquid is stopped to be stirred, the aging is carried out for 7h at the water bath temperature of 40 ℃ to form gel, the gel is dried for 48h at the temperature of 70 ℃, the dried solid particles are roasted at the temperature of 500 ℃, and the grinding is carried out to obtain Ce0.91Ti0.09O2A carrier powder.
Example 2: ce0.92Ti0.08O2Preparing a catalyst;
2g of solid cerium nitrate (Ce (NO)3)2·6H2O) is dissolved in 30mL of absolute ethyl alcohol, 10mL of deionized water is added, the pH value of the solution is adjusted to 3 by glacial acetic acid, 0.1394mL of butyl titanate is added dropwise under the stirring state, the solution is heated to 60 ℃ in a water bath, the stirring reaction is continued for 3h to obtain reaction liquid, the reaction liquid is stopped to be stirred, the aging is carried out for 7h at the water bath temperature of 40 ℃ to form gel, the gel is dried for 48h at the temperature of 70 ℃, the dried solid particles are roasted at the temperature of 500 ℃, and the grinding is carried out to obtain Ce0.94Ti0.06O2A carrier powder.
Example 3: ce0.93Ti0.07O2Preparing a catalyst;
2g of solid cerium nitrate (Ce (NO)3)2·6H2O) is dissolved in 30mL of absolute ethyl alcohol, 10mL of deionized water is added, the pH value of the solution is adjusted to 3 by glacial acetic acid, 0.1219mL of butyl titanate is added dropwise under the stirring state, the solution is heated to 60 ℃ in a water bath, the stirring reaction is continued for 3h to obtain reaction liquid, the reaction liquid is stopped to be stirred, the aging is carried out for 7h at the water bath temperature of 40 ℃ to form gel, the gel is dried for 48h at the temperature of 70 ℃, the dried solid particles are roasted at the temperature of 500 ℃, and the grinding is carried out to obtain Ce0.96Ti0.04O2A carrier powder.
Example 4: 8% Na/Ce0.92Ti0.08O2Preparing a catalyst;
will 207.27mg sodium carbonate was dissolved in 5mL deionized water and 1gCe was added to the sodium carbonate solution0.92Ti0.08O2Subjecting the composite oxide powder to ultrasonic treatment for 2h, drying at 80 ℃, heating to 500 ℃ at a speed of 3 ℃/min, roasting, keeping the temperature for 2h, and grinding to obtain 8% Na/Ce0.92Ti0.08O2A catalyst.
Example 5: 8% K/Ce0.92Ti0.08O2Preparing a catalyst;
118.10mg of potassium carbonate was dissolved in 5mL of deionized water, and 1gCe was added to the potassium carbonate solution0.92Ti0.08O2Subjecting the composite oxide powder to ultrasonic treatment for 2h, drying at 80 ℃, then heating to 500 ℃ at the speed of 3 ℃/min, roasting, keeping the temperature for 2h, and grinding to obtain 8% K/Ce0.92Ti0.08O2A catalyst.
Example 6: 8% Cs/Ce0.92Ti0.08O2Preparing a catalyst;
106.59mg of cesium carbonate was dissolved in 5mL of deionized water, and 1gCe was added to the cesium carbonate solution0.92Ti0.08O2Carrying out ultrasonic treatment on the composite oxide powder for 2h, drying at 80 ℃, then heating to 500 ℃ at the speed of 3 ℃/min, roasting, keeping the temperature for 2h, and grinding to obtain 8% Cs/Ce0.92Ti0.08O2A catalyst.
Example 7: ce0.92Ti0.08O28% Cs/Ce loading of 1.25 wt% DPF0.92Ti0.08O2Preparation of DPF-1 monolithic catalyst;
firstly, the DPF carrier is ultrasonically treated in water for 2 hours and dried at 100 ℃. 6g of solid cerium nitrate (Ce (NO)3)2·6H2O) is dissolved in 90mL of absolute ethyl alcohol, 30mL of deionized water is added, the pH value of the solution is adjusted to 3 by glacial acetic acid, 0.418mL of butyl titanate is added dropwise under the stirring state, the solution is heated to 60 ℃ in a water bath, the stirring reaction is continued for 3h to obtain sol, a dried DPF carrier is put into the sol, the sol is kept still for 6h at the water bath temperature of 40 ℃, the DPF after being soaked in the sol is put into a drying box to be dried for 46h at the temperature of 70 ℃, and the roasting is carried out at the temperature of 500 ℃ to obtain Ce0.92Ti0.08O2The load is DPF1.25wt% of monolithic catalyst Ce0.92Ti0.08O2/DPF-1；
69.64mg of cesium carbonate was dissolved in 50mL of deionized water, and Ce was added to the cesium carbonate solution0.92Ti0.08O2The DPF monolithic catalyst is treated by ultrasonic for 2h, dried at 80 ℃, then heated to 500 ℃ at the speed of 3 ℃/min for roasting, and the temperature is kept for 2h, thus obtaining the Ce0.92Ti0.08O28% Cs/Ce loading of 1.25 wt% DPF0.92Ti0.08O2Monolithic catalyst for DPF-1.
Example 8: ce0.92Ti0.08O28% Cs/Ce loading of 2.5 wt% DPF0.92Ti0.08O2Preparation of DPF-2 monolithic catalyst;
firstly, the DPF carrier is ultrasonically treated in water for 2 hours and dried at 100 ℃. 6g of solid cerium nitrate (Ce (NO)3)2·6H2O) is dissolved in 90mL of absolute ethyl alcohol, 30mL of deionized water is added, the pH value of the solution is adjusted to 3 by glacial acetic acid, 0.418mL of butyl titanate is added dropwise under the stirring state, the solution is heated to 60 ℃ in a water bath, the stirring reaction is continued for 3 hours to obtain sol, a dried DPF carrier is put into the sol, the sol is kept still for 8 hours at the temperature of 40 ℃ in the water bath, the DPF soaked with the sol is put into a drying box to be dried for 48 hours at the temperature of 70 ℃, the roasting is carried out at the temperature of 500 ℃, the step of soaking to roasting is repeated for two times to obtain the Ce, and the Ce is obtained0.92Ti0.08O2Ce loaded in 2.5 wt% of DPF0.92Ti0.08O2a/DPF-2 monolithic catalyst;
139.28mg of cesium carbonate was dissolved in 50mL of deionized water, and Ce was added to the cesium carbonate solution0.92Ti0.08O2The DPF monolithic catalyst is treated by ultrasonic for 2h, dried at 80 ℃, then heated to 500 ℃ at the speed of 3 ℃/min for roasting, and the temperature is kept for 2h, thus obtaining the Ce0.92Ti0.08O28% Cs/Ce loading of 2.5 wt% DPF0.92Ti0.08O2Monolithic catalyst for DPF-2.
Example 9: ce0.92Ti0.08O28% Cs/Ce loading of 3.75 wt% DPF0.92Ti0.08O2Preparation of DPF-3 monolithic catalyst;
firstly, the DPF carrier is ultrasonically treated in water for 2 hours and dried at 100 ℃. 6g of solid cerium nitrate (Ce (NO)3)2·6H2O) is dissolved in 90mL of absolute ethyl alcohol, 30mL of deionized water is added, the pH value of the solution is adjusted to 3 by glacial acetic acid, 0.418mL of butyl titanate is added dropwise under the stirring state, the solution is heated to 60 ℃ in a water bath, the stirring reaction is continued for 3 hours to obtain sol, a dried DPF carrier is put into the sol, the sol is kept still for 10 hours at the temperature of 40 ℃ in the water bath, the DPF after being soaked with the sol is put into a drying box to be dried for 550 hours at the temperature of 70 ℃, the roasting is carried out at the temperature of 500 ℃, the step of soaking to roasting is repeated twice to obtain Ce0.92Ti0.08O2Ce loaded in 3.75 wt% of DPF0.92Ti0.08O2a/DPF-3 monolithic catalyst;
208.92mg of cesium carbonate was dissolved in 50mL of deionized water, and Ce was added to the cesium carbonate solution0.92Ti0.08O2The DPF monolithic catalyst is treated by ultrasonic for 2h, dried at 80 ℃, then heated to 500 ℃ at the speed of 3 ℃/min for roasting, and the temperature is kept for 2h, thus obtaining the Ce0.92Ti0.08O28% Cs/Ce loading of 3.75 wt% DPF0.92Ti0.08O2Monolithic catalyst for DPF-3.
Example 10; ce0.92Ti0.08O28% Cs/Ce loading of 2.5 wt% DPF0.92Ti0.08O2Preparation of DPF monolithic catalyst;
firstly, the DPF carrier is ultrasonically treated for 1.5h in water and dried at 90 ℃. 6g of solid cerium nitrate (Ce (NO)3)2·6H2O) is dissolved in 90mL of absolute ethyl alcohol, 30mL of deionized water is added, the pH value of the solution is adjusted to 2.5 by glacial acetic acid, 0.418mL of butyl titanate is added dropwise under the stirring state, the solution is heated to 50 ℃ in a water bath, the stirring reaction is continued for 2 hours to obtain sol, a dried DPF carrier is put into the sol, the sol is kept still for 10 hours at the temperature of 30 ℃ in the water bath, the DPF after being soaked with the sol is put into a drying box to be dried for 50 hours at the temperature of 60 ℃, the roasting is carried out at the temperature of 400 ℃, the step of soaking to roasting is repeated twice to obtain Ce0.92Ti0.08O2The load amount is DPF2.5 wt.% Ce0.92Ti0.08O2a/DPF monolithic catalyst;
139.28mg of cesium carbonate was dissolved in 50mL of deionized water, and Ce was added to the cesium carbonate solution0.92Ti0.08O2The DPF monolithic catalyst is subjected to ultrasonic treatment for 1.5h, dried at 70 ℃, then heated to 450 ℃ at the speed of 2 ℃/min for roasting, and kept warm for 2.5h to obtain Ce0.92Ti0.08O28% Cs/Ce loading of 2.5 wt% DPF0.92Ti0.08O2a/DPF monolithic catalyst.
Example 11; ce0.92Ti0.08O28% Cs/Ce loading of 2.5 wt% DPF0.92Ti0.08O2Preparation of DPF monolithic catalyst;
firstly, the DPF carrier is subjected to ultrasonic treatment in water for 2.5 hours and is dried at 110 ℃. 6g of solid cerium nitrate (Ce (NO)3)2·6H2O) is dissolved in 90mL of absolute ethyl alcohol, 30mL of deionized water is added, the pH value of the solution is adjusted to 2.5 by glacial acetic acid, 0.418mL of butyl titanate is added dropwise under the stirring state, the solution is heated to 70 ℃ in a water bath, the stirring reaction is continued for 4 hours to obtain sol, a dried DPF carrier is put into the sol, the sol is kept still for 6 hours at the water bath temperature of 50 ℃, the DPF after being soaked with the sol is put into a drying box to be dried for 46 hours at the temperature of 80 ℃, the roasting is carried out at the temperature of 600 ℃, the step of soaking to roasting is repeated twice to obtain Ce0.92Ti0.08O2Ce loaded in 2.5 wt% of DPF0.92Ti0.08O2a/DPF monolithic catalyst;
139.28mg of cesium carbonate was dissolved in 50mL of deionized water, and Ce was added to the cesium carbonate solution0.92Ti0.08O2The DPF monolithic catalyst is subjected to ultrasonic treatment for 2.5h, dried at 90 ℃, then heated to 550 ℃ at the speed of 4 ℃/min for roasting, and the temperature is kept for 1.5h, thus obtaining Ce0.92Ti0.08O28% Cs/Ce loading of 2.5 wt% DPF0.92Ti0.08O2a/DPF monolithic catalyst.
Experiments prove that:
ce prepared in examples 1-3 of the invention1-xTixO2CompoundingOxide, x is more than or equal to 0.07 and less than or equal to 0.09; examples 4-6 preparation of M/Ce with different alkali metals loading1-xTixO2，M metal is Cs, K or Na, and x is 0.08; examples 7-9 catalysts of different loadings were prepared and coated onto cordierite DPF filters to obtain monolithic catalysts of different catalyst loadings for catalytic oxidation of soot particles.
15mg of soot particles and 150mg of powdered catalyst were weighed out and ground in an agate mortar for 10min to be in close contact. The sample was placed in a quartz tube of 5mm diameter for the experiment, with a heating rate of 3 ℃/min, from 150 ℃ to 650 ℃. At 150 ℃, the concentration of N is 300mL/min2The pretreatment was carried out under a gas stream for 0.5 h. With N2As an equilibrium gas, the reaction gas contained 2000ppm NO and 10% O2The gas flow rate was 500 mL/min. Outlet end CO2The concentration was measured by an LB-MS5X gas analyzer. The characteristic temperatures recorded at 10%, 50% and 90% soot conversion are T10、T50、T90Wherein T90Representing the burn-off temperature of the soot. By TiRepresenting the ignition temperature of soot, i.e. outlet CO2Temperature at which the concentration reaches 0.01%. The activity test of the monolithic catalyst is to dissolve the soot particles in ethanol, and then immerse the dried monolithic catalyst in the ethanol solution containing the soot particles for 30min of ultrasonic treatment. The monolithic catalyst evenly coated with the soot particles is dried for 12 hours, and then the monolithic catalyst is put into a quartz tube with the diameter of 50mm, and the activity test experiment is the same as that of the powdery catalyst.
1. Ce prepared by FIG. 1 inventive examples 1-31-xTixO2Catalyzing CO in soot process2The graph of concentration (a) and soot conversion (b) shows that Ce with different Ti contents1-xTixO2Composite oxide catalytic oxidation of Ce in soot activity0.92Ti0.08O2The catalyst has the best activity and the ignition temperature T of the oxidation sootiAt 343 ℃ and a temperature T at which 90% conversion occurs90At 458 ℃;
2. M/Ce prepared by FIG. 2 inventive examples 4-61-xTixO2M is Cs, K or Na, x is 0.08 and Ce0.92Ti0.08O2Catalyzing CO in soot process2The graphs of the concentration (a) and the soot conversion (b) show that different alkali metal loading Ce can be seen1-xTixO2M/Ce of catalyst1-xTixO2Catalyst catalytic oxidation soot activity, 8% Cs/Ce0.92Ti0.08O2Has the best activity, TiAt 319 ℃ T90At 421 ℃;
3. FIG. 3 8% Cs/Ce prepared by the invention of examples 7-91-xTixO2Catalyst for catalyzing CO in soot process by using monolithic catalyst of 0.08 x in DPF2Concentration (a) and soot conversion (b) 8% Cs/Ce in the graph0.92Ti0.08O2Example 7,/DPF-1, 8% Cs/Ce0.92Ti0.08O2Example 8,/DPF-2, 8% Cs/Ce0.92Ti0.08O2Example 9 for DPF-3 it can be seen that the activity of the monolithic catalyst for oxidizing soot at different catalyst loadings, Ce in example 80.92Ti0.08O2The monolithic catalyst with 2.5 wt% DPF has the best catalysis and activity, TiAt 323 ℃ T90491 ℃.
4. Ce of example 2 of the present invention can be seen from FIG. 40.92Ti0.08O2The catalyst is composed of irregular particles, and the agglomeration or accumulation of the nano particles forms a mesoporous structure. Example 6 of the present invention is at Ce0.92Ti0.08O2The catalyst is loaded with the alkali metal Cs, and the loaded alkali metal does not change the particle structure of the catalyst, so that the Cs is highly dispersed on the surface of the catalyst.
5. It is found from fig. 5 that the DPF sample without catalyst coating (fig. 5a) has a relatively flat cross section and relatively sharp corners; after coating the catalyst, inventive example 8: 8% Cs/Ce0.92Ti0.08O2The cross section of the DPF-2 (FIG. 5b) becomes uneven, and the edges become blunt and rounded, giving a coating feeling. According to FIG. 5c, after magnification, a significant particle growth over the surface of the DPF sample is seen, indicating catalysisThe agent has been uniformly coated on the DPF filter body.

Claims (10)

1. A preparation method of a monolithic catalyst is characterized by comprising the following steps: the method comprises the following steps:
(1) preparation of Ce by sol-gel method1-xTixO2Carrier:
dissolving 1-3g of solid cerium nitrate in 30mL of absolute ethyl alcohol according to the following proportion, and then adding 10mL of deionized water to obtain a product A; the chemical formula of the solid cerium nitrate is Ce (NO)3)2·6H2O；
Regulating the pH value of the product A with glacial acetic acid to make the pH value of the product A be 2.5-3.5 to obtain a product B;
thirdly, under the stirring state, dropwise adding butyl titanate into the product B, then heating in a water bath at 50-70 ℃, and stirring for reaction for 2-4h to obtain a reaction solution, namely a product C;
fourthly, performing ultrasonic cleaning on the cordierite-based diesel vehicle particulate matter catcher-DPF in water for 1.5 to 2.5 hours, and drying at 90 to 110 ℃ to obtain a D product;
fifthly, putting the product D into the product C, heating in water bath at 30-50 ℃, aging for 6-10h, and drying at 60-80 ℃ for 46-50h to obtain a product E;
sixthly, roasting the E product at the temperature of 400-600 ℃ to obtain Ce1-xTixO2The load is 1.25-3.75 wt% of integral catalyst of DPF, which is F product; and said Ce is1-xTixO2X is more than or equal to 0.07 and less than or equal to 0.09;
(2) impregnation method for preparing M/Ce1-xTixO2Catalyst:
adding F into alkali metal carbonate solution to control the active component load of carbonate solution to Ce1- xTixO26-10% of the carrier mass, ultrasonic treatment for 1.5-2.5h, drying at 70-90 ℃, then heating to 450-550 ℃ at the speed of 2-4 ℃/min, roasting, and keeping the temperature for 1.5-2.5h to obtain M/Ce1-xTixO2The metal of M is Cs, K or Na, and x is more than or equal to 0.07 and less than or equal to 0.09.
2. The process for preparing a monolithic catalyst according to claim 1, characterized in that: in the step I, 2g of solid cerous nitrate is dissolved in 30mL of absolute ethyl alcohol according to the following proportion, and then 10mL of deionized water is added.
3. The process for preparing a monolithic catalyst according to claim 1, characterized in that: and in the second step, the pH value of the product A is adjusted by glacial acetic acid to ensure that the pH value of the product A is 2.
4. The process for preparing a monolithic catalyst according to claim 1, characterized in that: in the third step, in a stirring state, according to the molar ratio of Ce to Ti of 1-x: and x, dropwise adding butyl titanate into the product B, heating in a water bath at 60 ℃, and stirring to react for 3 hours to obtain a reaction solution.
5. The process for preparing a monolithic catalyst according to claim 1, characterized in that: in the step IV, performing ultrasonic treatment on a cordierite-based diesel vehicle particulate matter catcher-DPF in water for 2 hours, and drying at 100 ℃.
6. The process for preparing a monolithic catalyst according to claim 1, characterized in that: in the fifth step, the product D is put into the product C, is heated in water bath for 7 hours at the temperature of 40 ℃, and is dried for 48 hours at the temperature of 70 ℃.
7. The process for preparing a monolithic catalyst according to claim 1, characterized in that: in the step, the D product is roasted at 500 ℃ to obtain Ce1-xTixO2The load of the monolithic catalyst is DPF2.5wt percent and is product E; and said Ce is1- xTixO2Wherein x is 0.08.
8. The process for preparing a monolithic catalyst according to claim 1, characterized in that: in the step (c), adding product E into the alkali metal carbonate solution, and controlling the loading amount of the active component of the carbonate solution to be Ce1-xTixO28 percent of the mass of the carrier,ultrasonic treating for 2h, drying at 80 deg.C, heating to 500 deg.C at 3 deg.C/min, calcining, and maintaining for 2h to obtain M/Ce1-xTixO2Finished DPF.
9. The process for preparing a monolithic catalyst according to claim 1, characterized in that: in the step (c), the alkali metal carbonate solution is Cs2CO3A solution; the M/Ce1-xTixO2In the DPF, the M metal is Cs, and x is 0.08.
10. Use of a monolithic catalyst according to any of claims 1 to 9, characterized in that: is M/Ce prepared by the preparation method of the monolithic catalyst1-xTixO2The DPF integrated catalyst is used in a diesel vehicle tail gas DPF reaction system to convert carbon smoke particles into nontoxic and pollution-free CO2The reaction temperature is 310-420 ℃, and the total flow of the gas is controlled to be 400-550 mL/min.
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