CN115805069A - Catalyst for diesel engine based on highly dispersed perovskite catalytic component and preparation method - Google Patents
Catalyst for diesel engine based on highly dispersed perovskite catalytic component and preparation method Download PDFInfo
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Abstract
The invention discloses a catalyst for diesel engine based on highly dispersed perovskite catalytic component, which uses La x Ce 1‑x Mn y Bi 1‑y O 3 perovskite-MoO type 3 The composite catalytic material nano-particles are used as a main catalytic active component and are supplemented with CeO 2 、ZrO 2 、γ‑Al 2 O 3 And cordierite honeycomb ceramics. The catalyst is coated on DOC, and can efficiently purify pollutants such as PM, HC, CO and the like discharged by a diesel engine. The main catalytic active component has the advantages of sulfur resistance, heat resistance and low cost; the catalytic activity of the whole catalyst is enhanced by improving the number of catalytic activity point sites per unit mass, the complete substitution of noble metals is realized, and in addition, perovskite and MoO are adopted 3 And meanwhile, the additive can generate a synergistic effect, further improve the catalytic activity of the catalyst and expand a high-activity temperature window. The dispersion effect of the perovskite precursor is remarkably improved by adopting the preparation method of firstly adsorbing and then gelling based on the carbon black adsorption matrix, and the nano particles have smaller size, uniform particle size and regular structure.
Description
Technical Field
The invention belongs to the technology of purifying pollutants in the tail gas of an internal combustion engine for a vehicle, and particularly relates to an oxidation catalyst for purifying pollutants such as Particulate Matters (PM), hydrocarbon (HC) and carbon monoxide (CO) in the exhaust gas of a diesel engine and a preparation method thereof.
Background
The diesel vehicle is the main force of heavy load and long-distance highway passenger and goods transportation at home and abroad at present, and makes remarkable contribution to the development of national economy and the convenience of social life. Meanwhile, due to the limitation of combustion modes, the pollutant emission of diesel vehicles is relatively serious, so that most countries in the world are prompted to make increasingly strict emission regulations to limit the pollutant emission of the diesel vehicles, and the development, popularization and application of the control technology of the exhaust pollutants of the diesel engine for vehicles are promoted. Among various diesel engine exhaust pollutant control technologies, a Diesel Oxidation Catalyst (DOC) is an effective technology for reducing HC and CO emissions, and at present, the DOC is almost a necessary exhaust pollutant purification device for a vehicular diesel engine. However, the traditional DOC needs to be coated with a catalytic coating which takes precious metal as a main catalytic active component, and the precious metal material has poor performance in the aspects of PM purification performance, sulfur poisoning resistance, thermal aging resistance, coking resistance and the like, and the price of the raw material is high, so that the operating conditions of modern advanced diesel engines are severe, and the requirements on fuel oil and lubricating components are extremely severe, so that the reduction/replacement technology of the precious metal catalytic material in the DOC has become a research hotspot at home and abroad.
The substituted perovskite and the transition metal oxide are the most potential substitute materials of the noble metal catalytic material in DOC all the time, the substituted perovskite and the transition metal oxide have excellent sulfur resistance, coking resistance and sintering resistance, the raw material cost is extremely low, the purification characteristics of HC and CO are similar to those of the noble metal catalytic material, but the purification efficiency of PM of the substituted perovskite and the transition metal oxide is lower than that of the noble metal catalytic material. On the other hand, the whole catalytic activity of the catalytic material is enhanced, besides the reaction capability of the catalytic active sites is improved, the number of the catalytic active sites is increased, an obvious effect can be obtained, the particle size of the catalytic active component particles in the catalyst is reduced, the specific surface area of the active component particles is increased, the exposure probability of the active component can be improved, and therefore the number of the catalytic active sites can be increased. Therefore, the preparation method of the high-dispersity ultrafine catalytic active component particles also becomes a core basic technology for popularization and application of substituted perovskites and transition metal oxides on DOC, and at present, the research on the technology is extremely intense at home and abroad.
Disclosure of Invention
Aiming at the prior art, the invention provides the catalyst for the diesel engine based on the highly dispersed perovskite catalytic component, which is simple and convenient to prepare, saves the preparation time and cost, and can obviously improve the dispersion effect of the perovskite precursor x Ce 1-x Mn y Bi 1-y O 3 Perovskite-type nanoparticle template and La x Ce 1-x Mn y Bi 1-y O 3 Preparation of La by perovskite nano particle template x Ce 1-x Mn y Bi 1-y O 3 Perovskite-molybdenum oxide (MoO) 3 ) Composite catalytic material nanoparticles, and La x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Composite catalytic material nano-particles as main catalytic active component and CeO 2 And ZrO 2 As a cocatalyst, gamma-Al 2 O 3 Is a coating auxiliary material.
In order to solve the technical problems, the catalyst for the diesel engine based on the highly dispersed perovskite catalytic component comprises a catalytic coating coated on a carrier, wherein the carrier is 400-mesh cordierite honeycomb ceramic, and the catalytic coating consists of a main catalytic active component, a cocatalyst and a coating auxiliary material; the cocatalyst consists of CeO 2 And ZrO 2 The coating auxiliary material consists of gamma-Al 2 O 3 Forming; the main catalytic active component consists of ABO 3 perovskite-MoO type 3 Composite catalytic material nano-particle composition, wherein, ABO 3 Perovskite and MoO 3 The mass percentage of the ABO is 60-90%/40-10%, and the ABO 3 Perovskite and MoO 3 The sum of the mass percentages of the components is 100 percent; the ABO 3 The A site of the perovskite consists of La and Ce, and the B site of the perovskite consists of Mn and Bi to form La x Ce 1-x Mn y Bi 1-y O 3 The perovskite type, wherein x represents the molar percentage of A-site La in the sum of the molar numbers of A-site Ce and La ions, and x = 60-90%; y represents the molar percentage proportion of the B-site Mn to the sum of the molar numbers of the two ions of the B-site Mn and the Bi, and y = 50-80%; meanwhile, the La x Ce 1-x Mn y Bi 1-y O 3 The ratio of the sum of the molar numbers of La ions and Ce ions to the sum of the molar numbers of Mn ions and Bi ions in the perovskite is 1:1; the La x Ce 1-x Mn y Bi 1-y O 3 The perovskite plays a role in the catalyst not only as one component in the main catalytic active component, but also can be used for preparing La x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Nanoparticle templates of composite catalytic material nanoparticles.
Further, the catalyst for diesel engine based on highly dispersed perovskite catalytic component according to the present invention comprises:
in the cocatalyst, the CeO 2 And ZrO 2 The mass percentage of the two components is 70-90%/10-30%, and the sum of the mass percentage of the two components is 100%.
The gamma-Al 2 O 3 Comprising gamma-Al from pure quality 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 Said pure gamma-Al 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 The mass percentage of the components is as follows: 80-90%/10-20%, the sum of the mass percent of the two is 100%.
The mass percentage of the main catalytic active component, the cocatalyst and the coating auxiliary material is 1-5%/4-10%/85-95%, and the sum of the mass percentage of the main catalytic active component, the cocatalyst and the coating auxiliary material is 100%.
The mass percentage of the catalytic coating and the carrier is 15-30%/85-70%, and the sum of the mass percentage of the catalytic coating and the carrier is 100%.
The invention provides a preparation method of the catalyst for the diesel engine based on the highly dispersed perovskite catalytic component, which comprises the following steps:
step 1, catalyst composition design: according to the proportion of each component, the following proportions are respectively designed: la in the main catalytic active ingredient x Ce 1-x Mn y Bi 1-y O 3 Perovskite and MoO 3 By mass of La x Ce 1-x Mn y Bi 1-y O 3 The mol percentage of La element and Ce element, the mol percentage of Mn element and Bi element in the perovskite type, and CeO in the cocatalyst 2 And ZrO 2 gamma-Al of 2 O 3 Pure gamma-Al in coating auxiliary materials 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 The mass percentages of the main catalytic active component, the cocatalyst and the coating auxiliary material, and the mass of the catalytic coating which can be generated by planning to prepare the coating slurry;
combined with 433.0g La (NO) 3 ) 3 ·6H 2 O preparation of 1mol La per 434.1g Ce (NO) 3 ) 3 ·6H 2 O preparation of 1mol Ce, every 173.0g Mn (CH) 3 COO) 2 Preparation of 1mol Mn, per 485.1g Bi (NO) 3 ) 3 ·5H 2 O preparation of 1mol Bi, and La x Ce 1-x Mn y Bi 1-y O 3 The ratio of the sum of the mole numbers of La, ce, mn and Bi elements in the perovskite nano-particle template to the mole number of the used glucose is 1:1-2, and the conversion ratio of 180.2g of the weight of each mole of glucose is calculated to prepare the La x Ce 1-x Mn y Bi 1-y O 3 La (NO) for perovskite nano-particle template 3 ) 3 ·6H 2 O、Ce(NO 3 ) 3 ·6H 2 O、Mn(CH 3 COO) 2 、Bi(NO 3 ) 3 ·5H 2 The mass of O and glucose; weighing La (NO) with determined mass 3 ) 3 ·6H 2 O、Ce(NO 3 ) 3 ·6H 2 O、Mn(CH 3 COO) 2 、Bi(NO 3 ) 3 ·5H 2 O, glucose and a mass between La (NO) 3 ) 3 ·6H 2 O、Ce(NO 3 ) 3 ·6H 2 O、Mn(CH 3 COO) 2 And Bi (NO) 3 ) 3 ·5H 2 0.8 to 1.5 times the sum of the masses of O and D 50 Adding the 6 raw materials into deionized water weighed according to the proportion that 1g of carbon black corresponds to 30-50 mL of deionized water, ultrasonically oscillating for 6-8 h, and heating the mixture of the 6 raw materials and the deionized water while ultrasonically oscillating to evaporate the mixture to dryness after 6-8 h to form wet gel; drying the wet gel at the temperature of 80-110 ℃ for 6-12 h to obtain dry gel; the xerogel is heated to 400 ℃ in a muffle furnace at a rate of 3 ℃/min and heldHolding for 2h, then heating to 700-800 ℃ at the speed of 10 ℃/min, calcining for 3-4 h, and obtaining La x Ce 1-x Mn y Bi 1-y O 3 A perovskite-type nanoparticle template;
binding per 196.0g (NH) 4 ) 2 MoO 4 Preparation of 144.0g of MoO 3 Calculating (NH) required for preparing the main catalytic active ingredient 4 ) 2 MoO 4 The mass of (c); weighing (NH) of determined mass 4 ) 2 MoO 4 And step 2 preparation of the obtained La x Ce 1-x Mn y Bi 1-y O 3 Perovskite type nanoparticle template, reacting said (NH) 4 ) 2 MoO 4 And La x Ce 1-x Mn y Bi 1-y O 3 Adding 1g (NH) of perovskite nano particle template 4 ) 2 MoO 4 In deionized water weighed according to the proportion of 50-500 ml of deionized water, ultrasonic oscillation is carried out to form slurry; using NaOH or HNO 3 Adjusting the pH of the slurry to a value in the range of 4 to 6, and grinding the slurry on a grinder to D 50 The particle size is in the range of 800-1000 nm, and then the ground slurry is heated while ultrasonic oscillation is carried out, so that the slurry is evaporated to dryness after 4-8 h to form a solid; drying the solid after evaporation to dryness at 80-110 ℃ for 6-12 h, then presintering at 350 ℃ for 2h, calcining at 500-550 ℃ for 2-3 h, and obtaining powdered and blocky solid La x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO 3 The composite catalytic material nano particles are main catalytic active ingredients of the catalyst;
step 4, preparing coating slurry: calculating CeO required for preparing the catalytic coating according to the proportion of each component designed in the step 1 and the quality of the catalytic coating which can be generated by planning to prepare the coating slurry 2 And ZrO 2 Mass of (2) and gamma-Al 2 O 3 The mass of the coating auxiliary materials;
bound per 434.2g Ce (NO) 3 ) 3 ·6H 2 O preparation of 172.1g CeO 2 Every 429.3g of Zr (NO) 3 ) 4 ·5H 2 O preparation 123.2g ZrO 2 And Al in the alumina sol 2 O 3 Calculating the mass percent of Ce (NO) required for preparing the coating slurry 3 ) 3 ·6H 2 O、Zr(NO 3 ) 4 ·5H 2 O and the mass of the alumina sol; in addition, the mass of the polyethylene glycol consumed for preparing the catalytic coating is calculated according to the proportion that every 100g of the catalytic coating needs 5-15 g of polyethylene glycol with the average molecular weight of 20000; weighing a defined mass of Ce (NO) 3 ) 3 ·6H 2 O、Zr(NO 3 ) 4 ·5H 2 O, pure gamma-Al 2 O 3 Powder, alumina sol, polyethylene glycol with molecular weight of 20000 and La prepared in step 3 x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO 3 Adding the 6 raw materials into deionized water with the mass 5-15 times of that of the catalytic coating prepared by planning, and performing ultrasonic oscillation to form slurry; with NaOH or HNO 3 Adjusting the pH of the slurry to a value in the range of 5 to 7, and grinding the slurry on a grinder to D 50 The grain diameter is in the range of 800-1000 nm, and the ground slurry is stirred for 48-72 h at the temperature of 50-70 ℃ to obtain coating slurry;
and 5, coating the catalytic coating on the carrier: designing the mass of said support to be coated with a catalytic coating; weighing the carrier with determined mass, immersing the carrier in the coating slurry at 50-70 ℃, and ensuring that the upper end surface of the carrier is slightly higher than the slurry liquid level; after the slurry is naturally lifted to fill all pore channels of the carrier, taking the carrier out of the slurry, blowing off residual fluid in the pore channels, drying at the temperature of 80-110 ℃ for 4-16 h, and roasting at the temperature of 500-600 ℃ for 2-4 h; repeating the processes of dipping, drying and roasting for 2-3 times to obtain the catalyst for the diesel engine based on the highly dispersed perovskite catalytic component.
The catalyst for the diesel engine based on the highly dispersed perovskite catalytic component prepared by the invention is packaged into a Diesel Oxidation Catalyst (DOC), and the diesel oxidation catalyst is arranged in an exhaust passage of the diesel engine, so that the high-efficiency oxidation purification of PM, HC and CO in the exhaust of the diesel engine is realized.
Compared with the prior art, the invention has the beneficial effects that:
the method for preparing the La by first adsorption and then gelation based on the carbon black adsorption matrix has the advantages of simple and convenient operation, preparation time saving and cost saving, can obviously improve the dispersion effect of the perovskite precursor, and is beneficial to preparing the La with smaller scale, uniform particle size and regular structure x Ce 1-x Mn y Bi 1-y O 3 Perovskite-type nanoparticles. And with La x Ce 1-x Mn y Bi 1-y O 3 The perovskite nano-particles are used as superfine particle templates, and La with high dispersity can be further prepared x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Composite catalytic material nanoparticles. La x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO 3 The main catalytic active component of the composite catalytic material nano-particle has the advantages of sulfur resistance, coking resistance, heat resistance and low cost, and can obviously increase the number of catalytic active sites per unit mass and improve the catalytic activity of the catalytic active sites, thereby improving the overall pollutant purification performance of the DOC, realizing the complete replacement of noble metal materials in the DOC and obviously reducing the raw material cost of the catalyst. Further, la x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 La in main catalytic active component of composite catalytic material nano-particles x Ce 1-x Mn y Bi 1-y O 3 Perovskite and MoO 3 And meanwhile, the additive can generate a synergistic interaction effect, further improve the overall catalytic activity of the catalyst and expand a high-activity temperature window.
Drawings
Fig. 1 is a schematic diagram of an engine evaluation system for diesel engine exhaust PM, HC, and CO purification performance.
Wherein: 1-a dynamometer; 2-a coupler; 3-test diesel engine; 4-an intake air flow meter; 5-an air inlet processor; 6-oil injector; 7-a fuel injection control system; 8-exhaust sampling port A; 9-temperature sensor a; 10-Diesel Oxidation Catalyst (DOC); 11-temperature sensor B; 12-exhaust sample port B; 13-a selective catalytic reduction catalyst; 14-a diesel particulate trap; 15-an exhaust sampling mechanism; 16-engine exhaust gas analyzer; 17-an exhaust gas filter; 18-air pump.
FIG. 2 shows an engine evaluation system using the purification performance of diesel exhaust PM, HC and CO at a diesel exhaust temperature of 300 ℃ and an airspeed of 50000h -1 The catalysts described in examples 1 to 3 exhibited efficiency in purifying PM, HC, and CO in diesel exhaust gas.
FIG. 3 shows an engine evaluation system using the purification performance of diesel exhaust PM, HC, and CO at a diesel exhaust temperature of 400 ℃ and a space velocity of 100000h -1 The catalysts described in examples 1 to 3 exhibited efficiency in purifying PM, HC, and CO in diesel exhaust gas.
Fig. 4 shows the efficiency of the catalysts of examples 1 to 3 for purifying PM, HC, and CO in diesel exhaust in the european steady state test cycle (ESC) test using the engine evaluation system for the performance of purifying PM, HC, and CO in diesel exhaust.
Detailed Description
The invention will be further described with reference to the following figures and specific examples, which are not intended to limit the invention in any way.
The catalyst for the diesel engine based on the highly dispersed perovskite catalytic component comprises a catalytic coating coated on a carrier, wherein the carrier is 400-mesh cordierite honeycomb ceramic, and the catalytic coating consists of a main catalytic active component, a cocatalyst and a coating auxiliary material; the cocatalyst is CeO 2 And ZrO 2 The coating auxiliary material consists of gamma-Al 2 O 3 The composition comprises the following components in percentage by weight:
(1) With La x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 The composite catalytic material nano-particles are used as main catalytic active ingredients, and the La x Ce 1-x Mn y Bi 1-y O 3 Perovskite and MoO type 3 The mass percentage of the components is as follows: 60-90%/40-10%, the sum of the mass percentages is 100%.
(2) The La x Ce 1-x Mn y Bi 1-y O 3 In the perovskite type, the molar percentages of La element and Ce element are as follows: 60-90%/10-40%, the sum of the mole percentages is 100%; the mol percentage of Mn element and Bi element is as follows: 50-80%/20-50%, the sum of the mole percentages is 100%; and the sum of the molar numbers of the La element and the Ce element is equal to the sum of the molar numbers of the Mn element and the Bi element; the La x Ce 1-x Mn y Bi 1-y O 3 The perovskite plays a role in the catalyst not only as one component in the main catalytic active component, but also can be used for preparing La x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Nanoparticle templates of composite catalytic material nanoparticles.
(3) With CeO 2 And ZrO 2 As a cocatalyst, and the CeO 2 And ZrO 2 The weight percentage of the components is as follows: 70-90%/10-30%, the sum of the mass percentages is 100%.
(4) With gamma-Al 2 O 3 Is a coating auxiliary material, and the gamma-Al 2 O 3 Respectively from pure gamma-Al 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 Said pure gamma-Al 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 The mass percentage of the components is as follows: 80-90%/10-20%, the sum of the mass percentages is 100%.
(5) The catalytic coating of the catalyst comprises the main catalytic active component, the cocatalyst and coating auxiliary materials, and the main catalytic active component, the cocatalyst and the coating auxiliary materials are as follows by mass percent: 1-5%/4-10%/85-95%, the sum of the mass percentages is 100%.
(6) The catalyst is composed of the catalytic coating and 400-mesh cordierite honeycomb ceramic, the 400-mesh cordierite honeycomb ceramic is used as a carrier of the catalyst, the catalytic coating is coated on the carrier, and the mass percentage ranges of the catalytic coating and the carrier are as follows: 15-30%/85-70%, the sum of the mass percentages is 100%.
The invention provides a catalyst for a diesel engine based on a highly dispersed perovskite catalytic component, which is suitable for purifying PM, HC and CO in diesel engine exhaust, takes carbon black as an adsorption matrix, and adopts the steps of adsorption and gelation x Ce 1- x Mn y Bi 1-y O 3 Perovskite-type nanoparticles of La x Ce 1-x Mn y Bi 1-y O 3 Preparation of La by using perovskite nano particles as template x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Composite catalytic material nanoparticles, and La x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Composite catalytic material nano-particles as main catalytic active component and CeO 2 And ZrO 2 As a cocatalyst, with gamma-Al 2 O 3 As coating auxiliary materials, the specific process mainly comprises the following 5 steps:
(1) Designing the composition of a catalyst;
(2)La x Ce 1-x Mn y Bi 1-y O 3 preparing a perovskite nano particle template;
(3) Preparing a main catalytic active ingredient;
(4) Preparing coating slurry;
(5) The catalytic coating is applied to the support.
The technical solution of the present invention is further described by the following specific embodiments in conjunction with the accompanying drawings. It should be noted that the present embodiments are illustrative and not restrictive, and the present invention is not limited to the following embodiments.
The catalyst for diesel engine based on highly dispersed perovskite catalytic component comprises: la x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Composite catalytic material nano-particle and CeO 2 、ZrO 2 、γ-Al 2 O 3 And 400 mesh cordierite honeycomb ceramic.
With La x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 The composite catalytic material nano-particles are used as main catalytic active ingredients, and the La x Ce 1-x Mn y Bi 1-y O 3 Perovskite and MoO 3 The mass percentage of the components is as follows: 60-90%/40-10%, the sum of the mass percentages is 100%.
The La x Ce 1-x Mn y Bi 1-y O 3 In the perovskite type, the molar percentages of La element and Ce element are as follows: 60-90%/10-40%, the sum of the mole percentages is 100%; the mol percentage of Mn element and Bi element is as follows: 50-80%/20-50%, the sum of the mole percentages is 100%; and the sum of the molar numbers of the La element and the Ce element is equal to the sum of the molar numbers of the Mn element and the Bi element; the La x Ce 1-x Mn y Bi 1-y O 3 The perovskite plays a role in the catalyst not only as one component in the main catalytic active component, but also can be used for preparing La x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Nanoparticle templates of composite catalytic material nanoparticles.
With CeO 2 And ZrO 2 As a cocatalyst, and the CeO 2 And ZrO 2 The mass percentage of the components is as follows: 70-90%/10-30%, the sum of the mass percentages is 100%.
With gamma-Al 2 O 3 Is a coating auxiliary material, and the gamma-Al 2 O 3 Respectively from pure gamma-Al 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 Said pure gamma-Al 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 The weight percentage of the components is as follows: 80-90%/10-20%, the sum of the mass percentages is 100%.
The catalytic coating of the catalyst comprises the main catalytic active component, the cocatalyst and coating auxiliary materials, and the main catalytic active component, the cocatalyst and the coating auxiliary materials are as follows by mass percent: 1-5%/4-10%/85-95%, the sum of the mass percentages is 100%.
The catalyst of the invention is formed by combining the catalytic coating and 400-mesh cordierite honeycomb ceramic, the 400-mesh cordierite honeycomb ceramic is a carrier of the catalyst of the invention, the catalytic coating is required to be coated on the carrier, and the mass percentage ranges of the catalytic coating and the carrier are as follows: 15-30%/85-70%, the sum of the mass percentages is 100%.
The method for preparing the catalyst of the present invention is described in detail below with reference to specific examples.
Example 1
(1) Catalyst composition design
The following proportions are respectively designed: la x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 La in composite catalytic material nano-particles x Ce 1-x Mn y Bi 1-y O 3 Perovskite and MoO 3 The mass percentage of the components is as follows: 90%/10%, la x Ce 1-x Mn y Bi 1-y O 3 The mol percentage of La element and Ce element in the perovskite type is as follows: 60%/40%, and the molar percentages of Mn element and Bi element are as follows: 50%/50% of CeO in cocatalyst 2 And ZrO 2 The mass percentage of the components is as follows: 70%/30%, gamma-Al 2 O 3 Pure gamma-Al in coating auxiliary material 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 The weight percentage of the components is as follows: 80%/20%, the mass percent of the main catalytic active component, the cocatalyst and the coating auxiliary material is as follows: 1%/4%/95%, and the coating slurry was planned to be formulated to produce 2000g of catalytic coating.
(2)La x Ce 1-x Mn y Bi 1-y O 3 Preparation of perovskite nano particle template
14.6g La (NO) was weighed 3 ) 3 ·6H 2 O、9.8g Ce(NO 3 ) 3 ·6H 2 O、4.9g Mn(CH 3 COO) 2 、13.7g Bi(NO 3 ) 3 ·5H 2 O, 40g glucose and 60g median particle diameter (D) 50 Particle size) of 452nm, adding the 6 raw materials into 3L of deionized water, performing ultrasonic oscillation for 6 hours, and heating a mixture of the 6 raw materials and the deionized water while performing ultrasonic oscillation to evaporate the mixture to dryness after 8 hours to form wet gel; drying the wet gel at 80 ℃ for 12h to obtain dry gel; heating the xerogel to 400 ℃ at the speed of 3 ℃/min in a muffle furnace, keeping for 2h, then heating to 800 ℃ at the speed of 10 ℃/min, and calcining for 3h to obtain La x Ce 1-x Mn y Bi 1-y O 3 A perovskite-type nanoparticle template.
(3) Preparation of the Main catalytic active ingredient
2.7g (NH) are weighed 4 ) 2 MoO 4 And the La prepared in the step (2) x Ce 1-x Mn y Bi 1-y O 3 Adding the 2 raw materials into 1350ml of deionized water, and performing ultrasonic oscillation to form a slurry; using NaOH or HNO 3 Adjusting the pH of the slurry to a value in the range of 4 to 6, and grinding the slurry on a grinder to D 50 The particle size is in the range of 800-1000 nm, and then the ground slurry is heated while ultrasonic oscillation is carried out, so that the slurry is evaporated to dryness after 8 hours to form a solid. Drying the solid after drying by distillation at 80 ℃ for 12h, then presintering at 350 ℃ for 2h, and calcining at 500 ℃ for 3h to obtain powdery and blocky solid. The powdery and blocky solid obtained after calcination is La x Ce 1-x Mn y Bi 1- y O 3 perovskite-MoO type 3 Composite catalytic material nanoparticles.
(4) Coating slurry preparation
141.3g Ce (NO) was weighed out 3 ) 3 ·6H 2 O、83.6g Zr(NO 3 ) 4 ·5H 2 O, 1520g pure gamma-Al 2 O 3 Powder, 1900g Al 2 O 3 20% mass content of alumina sol, 300g molecular weight 20000 polyethylene glycol and La prepared in step (3) x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Adding the 6 raw materials into 10kg of deionized water together, and performing ultrasonic oscillation to form slurry; using NaOH or HNO 3 Adjusting the pH of the slurry to a value in the range of 5 to 7 and grinding the slurry on a grinder to D 50 The grain diameter is in the range of 800-1000 nm, and the ground slurry is stirred for 48 hours at 70 ℃ to obtain coating slurry.
(5) Applying a catalytic coating to a support
Weighing 1kg of the carrier, immersing the carrier in the coating slurry at 70 ℃, and ensuring that the upper end surface of the carrier is slightly higher than the slurry liquid level; and after the slurry is naturally lifted to fill all pore channels of the carrier, taking the carrier out of the slurry, blowing off residual fluid in the pore channels, drying at 110 ℃ for 4h, and roasting at 500 ℃ for 4h. Repeating the processes of dipping, drying and roasting for 3 times to obtain the catalyst for the diesel engine based on the highly dispersed perovskite catalytic component.
Example 2
(1) Catalyst composition design
The following proportions are respectively designed: la x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 La in composite catalytic material nano-particles x Ce 1-x Mn y Bi 1-y O 3 Perovskite and MoO 3 The weight percentage of the components is as follows: 60%/40%, la x Ce 1-x Mn y Bi 1-y O 3 The mol percentage of La element and Ce element in the perovskite type is as follows: 90%/10%, and the mol percentage of Mn element and Bi element is as follows: 80%/20% of CeO in cocatalyst 2 And ZrO 2 The mass percentage of the components is as follows: 90%/10%, gamma-Al 2 O 3 Pure gamma-Al in coating auxiliary material 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 The mass percentage of the components is as follows: 90%/10%, the mass of the main catalytic active component, the cocatalyst and the coating auxiliary materialThe percentage is as follows: 5%/10%/85%, and the coating slurry was planned to be formulated to produce 2000g of catalytic coating.
(2)La x Ce 1-x Mn y Bi 1-y O 3 Preparation of perovskite nano particle template
85.7g La (NO) was weighed out 3 ) 3 ·6H 2 O、9.6g Ce(NO 3 ) 3 ·6H 2 O、30.4g Mn(CH 3 COO) 2 、21.3g Bi(NO 3 ) 3 ·5H 2 O, 80g glucose and 120g median particle diameter (D) 50 Particle size) 373nm, adding the 6 raw materials into 3.6L of deionized water, performing ultrasonic oscillation for 8h, and heating a mixture of the 6 raw materials and the deionized water while performing ultrasonic oscillation to evaporate the mixture to dryness after 6h to form wet gel; drying the wet gel at 80 ℃ for 12 hours to obtain dry gel; heating the xerogel to 400 ℃ at the speed of 3 ℃/min in a muffle furnace, keeping for 2h, then heating to 700 ℃ at the speed of 10 ℃/min, and calcining for 4h to obtain La x Ce 1-x Mn y Bi 1-y O 3 A perovskite-type nanoparticle template.
(3) Preparation of the Main catalytic active ingredient
54.4g (NH) are weighed 4 ) 2 MoO 4 And the La prepared in the step (2) x Ce 1-x Mn y Bi 1-y O 3 Adding the 2 raw materials into 3000ml of deionized water, and performing ultrasonic oscillation to form a slurry; using NaOH or HNO 3 Adjusting the pH of the slurry to a value in the range of 4 to 6, and grinding the slurry on a grinder to D 50 The particle size is in the range of 800-1000 nm, and then the ground slurry is heated while ultrasonic oscillation is carried out, so that the slurry is evaporated to dryness after 4 hours to form a solid. Drying the solid after drying by distillation at 110 ℃ for 6h, then presintering at 350 ℃ for 2h, and calcining at 550 ℃ for 2h to obtain powdery and blocky solid. The powdery and blocky solid obtained after calcination is La x Ce 1- x Mn y Bi 1-y O 3 Perovskite type-MoO 3 Composite catalytic material nanoparticles.
(4) Coating slurry preparation
454.1g of Ce (NO) was weighed out 3 ) 3 ·6H 2 O、69.7g Zr(NO 3 ) 4 ·5H 2 O, 1530g of pure gamma-Al 2 O 3 Powder, 850g Al 2 O 3 20 percent of aluminum sol by mass, 100g of polyethylene glycol with the molecular weight of 20000 and La prepared in the step (3) x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Adding the 6 raw materials into 30kg of deionized water together, and performing ultrasonic oscillation to form slurry; using NaOH or HNO 3 Adjusting the pH of the slurry to a value in the range of 5 to 7 and grinding the slurry on a grinder to D 50 The grain diameter is in the range of 800-1000 nm, and the ground pulp is stirred for 72 hours at 50 ℃ to obtain coating pulp.
(5) Applying a catalytic coating to a support
Weighing 1kg of the carrier, immersing the carrier in the coating slurry at 50 ℃, and ensuring that the upper end surface of the carrier is slightly higher than the slurry liquid level; and after the slurry is naturally lifted to fill all pore channels of the carrier, taking the carrier out of the slurry, blowing off residual fluid in the pore channels, drying for 16h at 80 ℃, and roasting for 2h at 600 ℃. Repeating the processes of dipping, drying and roasting for 2 times to obtain the catalyst for the diesel engine based on the highly dispersed perovskite catalytic component.
Example 3
(1) Catalyst composition design
The following proportions are respectively designed: la x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 La in composite catalytic material nano-particles x Ce 1-x Mn y Bi 1-y O 3 Perovskite and MoO 3 The mass percentage of the components is as follows: 80%/20%, la x Ce 1-x Mn y Bi 1-y O 3 The mol percentage of La element and Ce element in the perovskite type is as follows: 80%/20%And the mol percentages of Mn element and Bi element are as follows: 60%/40% of CeO in cocatalyst 2 And ZrO 2 The mass percentage of the components is as follows: 80%/20%, gamma-Al 2 O 3 Pure gamma-Al in coating auxiliary material 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 The mass percentage of the components is as follows: 80%/20%, the mass percent of the main catalytic active component, the cocatalyst and the coating auxiliary material is as follows: 3%/7%/90%, and the coating slurry was planned to be formulated to produce 2000g of catalytic coating.
(2)La x Ce 1-x Mn y Bi 1-y O 3 Preparation of perovskite nano-particle template
Weighing 54.7g La (NO) 3 ) 3 ·6H 2 O、13.7g Ce(NO 3 ) 3 ·6H 2 O、16.4g Mn(CH 3 COO) 2 、30.7g Bi(NO 3 ) 3 ·5H 2 O, 60g glucose and 120g median particle diameter (D) 50 Particle size) 373nm, adding the 6 raw materials into 4.8L of deionized water, ultrasonically oscillating for 7h, and then heating a mixture of the 6 raw materials and the deionized water while ultrasonically oscillating to evaporate the mixture to dryness after 7h to form wet gel; drying the wet gel at 80 ℃ for 12h to obtain dry gel; heating the xerogel to 400 ℃ at the speed of 3 ℃/min in a muffle furnace, keeping for 2h, then heating to 800 ℃ at the speed of 10 ℃/min, and calcining for 3h to obtain La x Ce 1-x Mn y Bi 1-y O 3 A perovskite-type nanoparticle template.
(3) Preparation of the Main catalytic active ingredient
16.3g (NH) are weighed 4 ) 2 MoO 4 And the La prepared in the step (2) x Ce 1-x Mn y Bi 1-y O 3 Adding the 2 raw materials into 1600ml of deionized water, and performing ultrasonic oscillation to form a slurry; using NaOH or HNO 3 Adjusting the pH of the slurry to a value in the range of 4 to 6, and grinding the slurry on a grinder to D 50 The grain diameter is in the range of 800-1000 nm,the ground slurry was heated while being ultrasonically oscillated, so that the slurry was evaporated to dryness after 6 hours to become a solid. Drying the solid after drying by distillation at 100 ℃ for 8h, then presintering at 350 ℃ for 2h, and calcining at 550 ℃ for 2h to obtain powdery and blocky solid. The powdery and blocky solid obtained after calcination is La x Ce 1- x Mn y Bi 1-y O 3 perovskite-MoO type 3 Composite catalytic material nanoparticles.
(4) Coating slurry preparation
282.6g Ce (NO) is weighed 3 ) 3 ·6H 2 O、97.6g Zr(NO 3 ) 4 ·5H 2 O, 1440g pure gamma-Al 2 O 3 Powder, 1800g Al 2 O 3 20 percent of aluminum sol by mass, 200g of polyethylene glycol with the molecular weight of 20000 and La prepared in the step (3) x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Adding the 6 raw materials into 20kg of deionized water together, and performing ultrasonic oscillation to form slurry; using NaOH or HNO 3 Adjusting the pH of the slurry to a value in the range of 5 to 7 and grinding the slurry on a grinder to D 50 The grain diameter is in the range of 800-1000 nm, and the ground slurry is stirred for 60 hours at the temperature of 60 ℃ to obtain coating slurry.
(5) Applying a catalytic coating to a carrier
Weighing 1kg of the carrier, immersing the carrier in the coating slurry at 60 ℃, and ensuring that the upper end surface of the carrier is slightly higher than the slurry liquid level; and after the slurry is naturally lifted to fill all pore channels of the carrier, taking the carrier out of the slurry, blowing off residual fluid in the pore channels, drying at 100 ℃ for 8h, and roasting at 550 ℃ for 3h. Repeating the processes of dipping, drying and roasting for 3 times to obtain the catalyst for the diesel engine based on the highly dispersed perovskite catalytic component.
The catalysts prepared in examples 1 to 3 were evaluated for their purification performance for PM, HC, and CO in diesel exhaust by using the engine evaluation system for purification performance for PM, HC, and CO in diesel exhaust shown in fig. 1. Before the test, the catalysts prepared in examples 1 to 3 were cut and combined into monolithic catalysts, and the monolithic catalysts obtained by cutting and combining were packaged. The test method comprises the following steps:
(1) And (3) steady-state working condition test: the torque and the rotating speed of a test engine 3 are controlled by using the dynamometer 1 and the coupling 2, the fuel supply speed of the fuel injector 6 to the diesel engine is adjusted by the fuel injection control system 7, and the proportion of the exhaust flow of the engine to the volume of the catalyst is controlled to be 50000h respectively -1 And 100000h -1 And the average exhaust temperatures in a Diesel Oxidation Catalyst (DOC) 10 are controlled to be 300 ℃ and 400 ℃ respectively, and PM, HC and CO purification performance evaluation is carried out. The intake air flow measurement value of the intake air flow meter 4 provides feedback parameters for the control strategy of the fuel injection control system; and the intake air processor 5 supplies the engine with clean air of a specific temperature and humidity. The temperature sensor A9 and the temperature sensor B11 measure the exhaust gas temperatures at both ends of the DOC10, respectively, and the average temperature of the exhaust gas in the DOC10 can be obtained by calculating the average value of the two temperatures. Exhaust samples before and after being treated by the DOC10 enter an exhaust sampling mechanism 15 and an engine exhaust analyzer 16 through an exhaust sampling port A8 and an exhaust sampling port B12 respectively for PM, HC and CO specific emission analysis, and exhaust gas after exhaust component analysis is discharged out of a laboratory through an air pump 18 after particulate pollutants are purified by an exhaust filter 17. Meanwhile, after the residual exhaust gas after sampling of the test engine 3 is subjected to exhaust purification by the selective catalytic reduction catalyst 13 and the diesel particulate trap 14 in sequence, the residual exhaust gas is also purified of particulate pollutants by the exhaust filter 17 and then is discharged out of the laboratory by the air pump 18. By utilizing the engine evaluation system for the purification performance of diesel engine exhaust PM, HC and CO, the average exhaust temperature in DOC is 300 ℃, and the airspeed is 50000h -1 The average exhaust temperature in DOC is 400 ℃ and the space velocity is 100000h -1 The purification efficiencies of the catalysts prepared in examples 1 to 3 for diesel exhaust gases PM, HC and CO are shown in fig. 2 and 3, respectively.
(2) ESC test: the purification effect of the catalysts prepared in examples 1-3 on diesel engine exhaust PM, HC and CO is evaluated by adopting the diesel engine exhaust PM, HC and CO purification performance engine evaluation system according to ESC test specifications specified in national standard GB 17691-2005 [ limit emission values of vehicle compression ignition type and gas fuel ignition type engines and automobile exhaust pollutants and measurement methods (stages III, IV and V) as shown in FIG. 4.
In conclusion, the catalyst prepared by the invention can be coated on DOC to efficiently purify pollutants such as PM, HC and CO discharged by a diesel engine. The main catalytic active component of the composite catalytic material nano-particles has the advantages of sulfur resistance, heat resistance and low cost, and the catalytic activity of the whole catalyst is enhanced by improving the number of catalytic active point sites per unit mass, so that the complete substitution of noble metals is realized, and in addition, perovskite and MoO are adopted 3 And meanwhile, the catalyst can generate a synergistic interaction effect, so that the catalytic activity of the catalyst is further improved, and a high-activity temperature window is expanded. The method for preparing the perovskite precursor by adsorption first and then gelation based on the carbon black adsorption matrix obviously improves the dispersion effect of the perovskite precursor, and is favorable for preparing the composite catalytic material nano-particles with smaller size, uniform particle size and regular structure.
While the present invention has been described in connection with the appended drawings, the foregoing detailed description is intended to be illustrative rather than restrictive, and various changes may be made therein by those skilled in the art without departing from the spirit of the invention.
Claims (7)
1. A catalyst for diesel engine based on highly dispersed perovskite catalytic component comprises a catalytic coating coated on a carrier, wherein the carrier is 400-mesh cordierite honeycomb ceramic, and the catalytic coating is composed of a main catalytic active component, a cocatalyst and a coating auxiliary material; the cocatalyst is CeO 2 And ZrO 2 The coating auxiliary material consists of gamma-Al 2 O 3 Composition is carried out; the method is characterized in that:
the main catalytic active component consists of ABO 3 perovskite-MoO type 3 Composite catalytic material nano-particle composition, wherein, ABO 3 Perovskite and MoO 3 Is 60 to 90 percent by mass％/40～10％，ABO 3 Perovskite and MoO 3 The sum of the mass percentages of the components is 100 percent;
the ABO 3 The A site of the perovskite consists of La and Ce, and the B site of the perovskite consists of Mn and Bi to form La x Ce 1-x Mn y Bi 1-y O 3 The perovskite type, wherein x represents the mole percentage proportion of A site La in the sum of the mole numbers of A site Ce and La ions, and x = 60-90%; y represents the molar percentage proportion of the B-site Mn to the sum of the molar numbers of the two ions of the B-site Mn and the Bi, and y = 50-80%; meanwhile, the La x Ce 1-x Mn y Bi 1-y O 3 The ratio of the sum of the molar numbers of La ions and Ce ions to the sum of the molar numbers of Mn ions and Bi ions in the perovskite type is 1:1; the La x Ce 1-x Mn y Bi 1-y O 3 The perovskite plays a role in the catalyst not only as one component in the main catalytic active component, but also can be used for preparing La x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Nanoparticle templates of composite catalytic material nanoparticles.
2. The catalyst for diesel engine based on highly dispersed perovskite catalytic component as set forth in claim 1, wherein: in the cocatalyst, the CeO 2 And ZrO 2 The mass percentage of the two components is 70-90%/10-30%, and the sum of the mass percentage of the two components is 100%.
3. The catalyst for diesel engine based on highly dispersed perovskite catalytic component as set forth in claim 1, wherein: the gamma-Al 2 O 3 Comprising gamma-Al from pure nature 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 Said pure gamma-Al 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 The mass percentage of the components is as follows: 80-90%/10-20%, the sum of the mass percent of the two is 100%.
4. The catalyst for diesel engine based on highly dispersed perovskite catalytic component as set forth in claim 1, wherein: the mass percentage of the main catalytic active component, the cocatalyst and the coating auxiliary material is 1-5%/4-10%/85-95%, and the sum of the mass percentage of the main catalytic active component, the cocatalyst and the coating auxiliary material is 100%.
5. The catalyst for diesel engine based on highly dispersed perovskite catalytic component as set forth in claims 1 to 4, wherein: the mass percentage of the catalytic coating and the carrier is 15-30%/85-70%, and the sum of the mass percentage of the catalytic coating and the carrier is 100%.
6. A process for preparing a catalyst for diesel engines based on highly dispersed perovskite catalytic component as claimed in claims 1 to 5, characterized in that: the specific process comprises the following steps:
step 1, catalyst composition design:
according to the mixture ratio of the components of the claims 1-5, the following proportions are respectively designed: la in the main catalytic active ingredient x Ce 1- x Mn y Bi 1-y O 3 Perovskite and MoO 3 By mass of La x Ce 1-x Mn y Bi 1-y O 3 The mol percentage of La element and Ce element, the mol percentage of Mn element and Bi element in the perovskite type catalyst and CeO in the cocatalyst 2 And ZrO 2 gamma-Al in a mass percent of 2 O 3 Pure gamma-Al in coating auxiliary material 2 O 3 Powder and gamma-Al converted from alumina sol 2 O 3 The mass percentages of the main catalytic active component, the cocatalyst and the coating auxiliary material, and the mass of the catalytic coating which can be generated by planning to prepare the coating slurry;
step 2, la x Ce 1-x Mn y Bi 1-y O 3 Preparing a perovskite nano particle template:
calculating the La in the main catalytic active component according to the proportion of each component designed in the step 1 and the quality of the catalytic coating which can be generated by planning to prepare the coating slurry x Ce 1-x Mn y Bi 1-y O 3 Quality of perovskite nanoparticle template and La x Ce 1-x Mn y Bi 1- y O 3 The mole number of La, ce, mn and Bi elements in the perovskite nano-particle template;
combined with 433.0g La (NO) 3 ) 3 ·6H 2 O preparation of 1mol La per 434.1g Ce (NO) 3 ) 3 ·6H 2 O preparation of 1mol Ce, every 173.0g Mn (CH) 3 COO) 2 Preparation of 1mol Mn, per 485.1g Bi (NO) 3 ) 3 ·5H 2 O preparation of 1mol Bi, and La x Ce 1- x Mn y Bi 1-y O 3 The ratio of the sum of the mole numbers of La, ce, mn and Bi elements in the perovskite nano-particle template to the mole number of the used glucose is 1:1-2, and the conversion ratio of 180.2g of the weight of each mole of glucose is calculated to prepare the La x Ce 1- x Mn y Bi 1-y O 3 La (NO) for perovskite-type nanoparticles 3 ) 3 ·6H 2 O、Ce(NO 3 ) 3 ·6H 2 O、Mn(CH 3 COO) 2 、Bi(NO 3 ) 3 ·5H 2 The mass of O and glucose;
weighing La (NO) with determined mass 3 ) 3 ·6H 2 O、Ce(NO 3 ) 3 ·6H 2 O、Mn(CH 3 COO) 2 、Bi(NO 3 ) 3 ·5H 2 O, glucose and a mass between La (NO) 3 ) 3 ·6H 2 O、Ce(NO 3 ) 3 ·6H 2 O、Mn(CH 3 COO) 2 And Bi (NO) 3 ) 3 ·5H 2 0.8 to 1.5 times the sum of the mass of O and D 50 Adding the 6 raw materials into deionized water weighed according to the proportion that 1g of carbon black corresponds to 30-50 mL of deionized water, ultrasonically oscillating for 6-8 h, and heating the mixture of the 6 raw materials and the deionized water while ultrasonically oscillating to evaporate the mixture to dryness after 6-8 h to form wet gel; drying the wet gel at the temperature of 80-110 ℃ for 6-12 h to obtain the gelA xerogel; heating the xerogel to 400 ℃ at the speed of 3 ℃/min in a muffle furnace and keeping for 2h, then heating to 700-800 ℃ at the speed of 10 ℃/min, and calcining for 3-4 h to obtain La x Ce 1-x Mn y Bi 1-y O 3 A perovskite-type nanoparticle template;
step 3, preparation of main catalytic active ingredients:
calculating MoO in the main catalytic active component according to the proportion of each component designed in the step 1 and the quality of the catalytic coating which can be generated by planned coating slurry preparation 3 The mass of (c); binding per 196.0g (NH) 4 ) 2 MoO 4 Preparation of 144.0g of MoO 3 Calculating (NH) required for preparing the main catalytic active ingredient 4 ) 2 MoO 4 The mass of (c);
weighing (NH) of determined mass 4 ) 2 MoO 4 And step 2 preparation of the obtained La x Ce 1-x Mn y Bi 1-y O 3 Perovskite type nanoparticle template, reacting said (NH) 4 ) 2 MoO 4 And La x Ce 1-x Mn y Bi 1-y O 3 Adding 1g (NH) of perovskite nano particle template 4 ) 2 MoO 4 In deionized water weighed according to the proportion of 50-500 ml of deionized water, ultrasonic oscillation is carried out to form slurry; using NaOH or HNO 3 Adjusting the pH of the slurry to a value in the range of 4 to 6, and grinding the slurry on a grinder to D 50 The particle size is in the range of 800-1000 nm, and then the ground slurry is heated while ultrasonic oscillation is carried out, so that the slurry is evaporated to dryness after 4-8 h to form a solid;
drying the solid after evaporation to dryness at 80-110 ℃ for 6-12 h, then presintering at 350 ℃ for 2h, calcining at 500-550 ℃ for 2-3 h, and obtaining powdered and blocky solid La x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 The composite catalytic material nano particles are main catalytic active ingredients of the catalyst;
step 4, preparing coating slurry:
calculating CeO required for preparing the catalytic coating according to the proportion of each component designed in the step 1 and the quality of the catalytic coating which can be generated by planning to prepare the coating slurry 2 And ZrO 2 Mass of (2) and gamma-Al 2 O 3 The mass of the coating auxiliary materials;
bound per 434.2g Ce (NO) 3 ) 3 ·6H 2 O preparation of 172.1g CeO 2 Every 429.3g of Zr (NO) 3 ) 4 ·5H 2 O preparation 123.2gZrO 2 And Al in the alumina sol 2 O 3 Calculating the mass percent of Ce (NO) required for preparing coating slurry 3 ) 3 ·6H 2 O、Zr(NO 3 ) 4 ·5H 2 O and the mass of the alumina sol; in addition, the mass of the polyethylene glycol consumed for preparing the catalytic coating is calculated according to the proportion that every 100g of the catalytic coating needs 5-15 g of polyethylene glycol with the average molecular weight of 20000;
weighing a defined mass of Ce (NO) 3 ) 3 ·6H 2 O、Zr(NO 3 ) 4 ·5H 2 O, pure gamma-Al 2 O 3 Powder, alumina sol, polyethylene glycol with molecular weight of 20000 and La prepared in step 3 x Ce 1-x Mn y Bi 1-y O 3 perovskite-MoO type 3 Adding the 6 raw materials into deionized water with the mass 5-15 times of that of the catalytic coating prepared by planning, and performing ultrasonic oscillation to form slurry; with NaOH or HNO 3 Adjusting the pH of the slurry to a value in the range of 5 to 7, and grinding the slurry on a grinder to D 50 The grain diameter is in the range of 800-1000 nm, and the ground pulp is stirred for 48-72 hours at the temperature of 50-70 ℃ to obtain coating pulp;
and 5, coating the catalytic coating on the carrier:
designing the mass of said support to be coated with a catalytic coating; weighing the carrier with determined mass, immersing the carrier in the coating slurry at 50-70 ℃, and ensuring that the upper end surface of the carrier is slightly higher than the slurry liquid level; after the slurry is naturally lifted to fill all pore channels of the carrier, taking the carrier out of the slurry, blowing off residual fluid in the pore channels, drying at the temperature of 80-110 ℃ for 4-16 h, and roasting at the temperature of 500-600 ℃ for 2-4 h; repeating the processes of dipping, drying and roasting for 2-3 times to obtain the catalyst for the diesel engine based on the highly dispersed perovskite catalytic component.
7. The application of the catalyst for the diesel engine based on the highly dispersed perovskite catalytic component, which is prepared by the preparation method of claim 6, according to any one of claims 1 to 5, packaged as a Diesel Oxidation Catalyst (DOC), wherein the diesel oxidation catalyst is installed in an exhaust passage of the diesel engine to realize efficient oxidation and purification of PM, HC and CO in exhaust gas of the diesel engine.
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