Preparation method of wall-flow type particle trapping catalyst
阅读说明：本技术 一种壁流式颗粒捕集型催化剂的制备方法 (Preparation method of wall-flow type particle trapping catalyst ) 是由 施文杰 金炜阳 岳军 王刚 周钧 张元� 贾莉伟 王家明 于 2021-08-13 设计创作，主要内容包括：本发明属于催化剂制备技术领域,具体涉及一种壁流式颗粒捕集型催化剂的制备方法。本发明的制备方法包括以下步骤：向配制的涂层材料浆液中加入分散剂和粘结剂后球磨,再向浆液中加入锁水剂,搅拌后形成成品浆液；将壁流式载体两端浸润疏水剂,将未堵孔端固定于涂覆设备上,定量给浆于载体端面,通过负压抽吸使涂层浆液均匀分布于载体壁,随后将载体置于烘箱中干燥至恒重,然后焙烧；再用与壁流式载体一致的泥料将壁流式载体按照两端交替堵孔,烘干烧结处理,即得到成品的壁流式颗粒捕集催化剂。本发明的壁流式颗粒捕集催化剂,其涂层材料在壁流式载体上分布均匀,在保证捕集率的前提下,成品催化剂背压低,能够满足工程应用要求。(The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of a wall-flow type particle trapping catalyst. The preparation method comprises the following steps: adding a dispersing agent and a binder into the prepared coating material slurry, then carrying out ball milling, adding a water locking agent into the slurry, and stirring to form a finished product slurry; soaking hydrophobic agent at two ends of the wall flow type carrier, fixing the non-blocked ends on coating equipment, quantitatively feeding slurry to the end faces of the carrier, uniformly distributing the coating slurry on the wall of the carrier by negative pressure suction, then placing the carrier in a drying oven, drying to constant weight, and then roasting; and then alternately plugging the wall flow type carrier according to two ends by using mud materials consistent with the wall flow type carrier, and drying and sintering to obtain the finished product of the wall flow type particle trapping catalyst. The wall flow type particle trapping catalyst has the advantages that the coating material is uniformly distributed on the wall flow type carrier, the back pressure of the finished product catalyst is low on the premise of ensuring the trapping rate, and the engineering application requirements can be met.)
1. A method of preparing a wall-flow particulate trapping catalyst, comprising the steps of:
step S1, preparing slurry containing a coating material, wherein the solid content of the coating material slurry is 15.0-35.0%, adding a dispersing agent and a binder into the slurry, performing ball milling dispersion, adding a water locking agent into the slurry, and stirring to form finished slurry for later use; wherein the addition amount of the dispersing agent is 1.0-5.0% of the weight of the cured substances in the slurry, the addition amount of the binder is 0.5-2.0% of the weight of the cured substances in the slurry, and the addition amount of the water locking agent is 0.5-5.0% of the weight of the cured substances in the slurry;
s2, soaking the two ends of the wall flow carrier with the end faces not blocked with the water repellent agent, fixing the wall flow carrier on coating equipment, quantitatively feeding slurry to the end faces of the wall flow carrier, uniformly distributing the coating slurry on the wall surfaces of the wall flow carrier through negative pressure suction, then placing the wall flow carrier in an oven with the temperature of 120-;
and S3, alternately plugging the non-plugged ends of the wall flow type carrier by pug, wherein the plugging depth is 5 +/-3 mm, drying the carrier at the temperature of 120-plus-150 ℃ for 1-3h, and sintering the carrier at the temperature of 400-plus-600 ℃ for 1-3h to obtain the finished product of the wall flow type particle trapping catalyst.
2. The method of preparing a wall-flow particulate trap catalyst according to claim 1, wherein the coating material in step S1 comprises an active component having a catalytic function and/or a component having a function of modifying the pores of the support.
3. A method of preparing a wall-flow particulate trap catalyst according to claim 1, wherein at least one of the ends of the wall-flow support is unplugged and is made of one of cordierite, silicon carbide or aluminum titanate.
4. A method of preparing a wall-flow particulate trap catalyst according to claim 1, wherein the wall-flow support is coated with one or both end coatings, with or without a plugged end.
5. The method of claim 1, wherein the binder is one of alumina sol, silica sol, and silica-alumina composite gel;
the hydrophobic agent is one of liquid hydrocarbons including naphtha and kerosene.
6. The method of claim 1, wherein the dispersant is one of sodium silicate, sodium aluminate, sodium citrate, sodium sulfonate, sodium laurate, sodium stearate, isopropanolamine, polyacrylic acid, and polyacrylamide.
7. The method of preparing a wall-flow particulate trap catalyst according to claim 1, wherein the water-blocking agent is a cellulose and derivatives thereof or a synthetic polymer;
the cellulose derivative is one or more of methyl cellulose, ethyl cellulose, isopropyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose and carboxymethyl ethyl cellulose;
the synthetic polymer is one or more of polyvinyl alcohol, polyethylene glycol and polypropylene glycol.
8. The method of preparing a wall-flow particulate trap catalyst according to claim 1 or 2, wherein the coating material is one of a metal-modified molecular sieve, a metal oxide or metal composite oxide, a noble metal-supported oxide or composite oxide; the noble metal is one or more of Pt, Pd and Rh.
9. The preparation method of the wall-flow type particle-trapping catalyst according to claim 8, wherein the modified metal of the molecular sieve is one or more of Cu, Fe, Co, Ni, Ce, Ag and Mn; the molecular sieve is one or more of BEA, CHA, MFI, LTA, AEI, AFX and FAU.
10. The method of preparing a wall-flow particulate trap catalyst according to claim 8, wherein the metal oxide is a transition metal oxide or an alkaline earth metal oxide;
the composite oxide is one or more of cerium-zirconium composite oxide, lanthanum-aluminum composite oxide, cerium-zirconium-lanthanum-aluminum composite oxide and cerium-aluminum composite oxide.
Technical Field
The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of a wall-flow type particle trapping catalyst.
Background
Particulate Matter (PM) is one of the main pollutants emitted from motor vehicle exhaust, and as media reports and related authoritative research issues, the harm of PM to human body is gradually known. According to the ecological environment department, "annual report of environmental management of China Motor vehicles (2020)": the nationwide motor vehicle reserves reach 3.48 million, with the total PM emissions for road fuel vehicles reaching 7.4 million tons, and for non-road fuel machines reaching 24 million tons.
Research has reported that ultrafine particles in automobiles have a size of less than 100nm, wherein particles having a particle size of less than 30nm account for about 90% of the total mass of the particles, but account for only 10% of the mass of PM. The ultrafine particles penetrate into the lung more easily than large particles, are dispersed in various parts of the lung, and have a greater respiratory tract irritation effect. At the same time, the smaller the particles, the larger the surface to volume value, which means that a large amount of potentially toxic substances can adhere to the surface of a mass of PM particles, and thus there will be a lot of toxic chemicals deposited in the lungs with the particles. The particulate matter entering the respiratory system can cause inflammation and damage to related organs, such as lower respiratory tract infection, chronic obstructive pulmonary disease, lung cancer and the like. In addition, ultrafine particles can also penetrate into the cardiovascular system causing a number of adverse health effects, including symptoms of hypertension, ischemic heart disease, cerebrovascular disease, and heart failure. Worldwide annual long term exposure to PM2.5About 420 million of the dead people caused by the exceeding environment, about 1.031 hundred million of the dead people cause related health problems, and the environment exposed to the exceeding particulate matter is confirmedIs the fifth most dangerous factor for health. Based on quantifying the relationship of ambient particulate matter concentration to increased mortality, the world health organization revised 2005 air quality guidelines, i.e., PM in the environment2.5The level is less than 10 mu g/m3Long term (year), less than 25 μ g/m3Short term (24 hours) as a risk line for health hazards. These health guidelines have been promulgated for over a decade, however, more than 90% of the world population still lives with particulate concentrations in excess of 10 μ g/m in surrounding areas3(year).
As PM causes serious harm to human health, the emission legislation of all countries in the world is more and more strict, and the continuous progress of corresponding particulate pollution treatment technical means is promoted. Wall-flow particle trapping catalyst is used as the most excellent main technical means for treating particulate matters in motor vehicle tail gas at present, and is increasingly widely applied commercially. Which comprises a wall-flow trapping carrier and a functional coating material. The carrier is made of various materials such as sintered metal, ceramic or metal fiber, and is a filter with certain porosity and alternately closed through holes at two ends, and the exhaust gas can pass through the holes, and particulate matters in the exhaust gas are prevented. The wall-flow type particle trapping carrier in commercial production mainly comprises three types of cordierite, silicon carbide and aluminum titanate, and at present, the metal type particle trapping carrier also starts to be popularized. The actual shape and size of the filter used in a vehicle, as well as properties such as the thickness of the channel walls and pore size distribution, etc., depend on the application concerned. The average size of the pores in the walls of the wall flow particulate capture support channel is typically in the range of 10 to 50 μm, typically with a median pore diameter of about 20 μm, whereas the size of the particulate matter emitted from the engine exhaust is much smaller than the median pore diameter of the pores of the support. It is necessary to modify the pore size of the wall-flow type particulate collection carrier.
In engineering applications, it is desirable to reduce the pressure drop of the aftertreatment assembly as much as possible in order to take fuel economy into account, on the premise that the efficiency of trapping the exhaust particulates is not compromised. In the existing whole set of catalyst system, the wall flow catalyst can only flow through the pores in the wall because the two ends of the wall flow catalyst are alternatively blocked, so that the pressure drop amplification of the whole system is decisive. Factors influencing the backpressure of the finished wall-flow trapping catalyst are as follows: coating slurry properties, coating process, porosity of the support, etc. The porosity is typically 40.0% to 60.0% in combination with the strength requirements of the support. Through recent years of research, the characteristics of the slurry and the coating process of the coating are gradually perfected and matured, and the backpressure of the wall-flow trapping catalyst is improved to a limited extent by optimizing the characteristics of the slurry and a simple coating process. Therefore, under the condition of ensuring the trapping rate, the wall-flow type trapping catalyst with the obvious advantage of low back pressure is prepared, and is particularly important for improving the fuel economy of an engine.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a preparation method of a wall-flow type particle-trapping catalyst. The technical scheme of the invention can realize uniform distribution of the coating material on the wall-flow carrier, and effectively reduce the back pressure of the finished catalyst on the premise of ensuring the trapping rate. The pressure drop of the whole post-treatment assembly is effectively improved while the engineering application is met, and the fuel economy of the whole vehicle is improved.
In order to achieve the technical purpose, the embodiment of the invention adopts the technical scheme that: a method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
step S1, preparing slurry containing a coating material, wherein the solid content of the slurry containing the coating material is 15.0-35.0%, adding a dispersing agent and a binder into the slurry, performing ball milling dispersion, adding a water locking agent into the slurry, and stirring to form finished slurry for later use; wherein, the addition amount of the dispersing agent is 1.0-5.0 percent of the weight of the cured substances in the slurry, the addition amount of the binding agent is 0.5-2.0 percent of the weight of the cured substances in the slurry, and the addition amount of the water locking agent is 0.5-5.0 percent of the weight of the cured substances in the slurry;
s2, soaking the two ends of the wall flow carrier with the end faces not blocked with the water repellent agent, fixing the wall flow carrier on coating equipment, quantitatively feeding slurry to the end faces of the wall flow carrier, uniformly distributing the coating slurry on the wall surfaces of the wall flow carrier through negative pressure suction, then placing the wall flow carrier in an oven with the temperature of 120-;
and S3, alternately plugging the non-plugged ends of the wall flow type carrier by pug, wherein the plugging depth is 5 +/-3 mm, drying the carrier at the temperature of 120-plus-150 ℃ for 1-3h, and sintering the carrier at the temperature of 400-plus-600 ℃ for 1-3h to obtain the finished product of the wall flow type particle trapping catalyst.
Further, the coating material in step S1 comprises an active component having a catalytic function and/or a component having a function of modifying pores of the support.
Furthermore, at least one end of the two ends of the wall flow type carrier is not blocked, and the material is one of cordierite, silicon carbide or aluminum titanate.
Further, the wall flow type carrier is coated in a mode of coating one end or coating both ends, coating the end with blocked holes or coating the end without blocked holes.
Further, the binder is one of alumina sol, silica sol and silicon-aluminum composite glue;
the hydrophobic agent is one of liquid hydrocarbons including naphtha and kerosene.
Further, the dispersing agent is one of sodium silicate, sodium aluminate, sodium citrate, sodium sulfonate, sodium laurate, sodium stearate, isopropanolamine, polyacrylic acid and polyacrylamide.
Further, the water locking agent is cellulose and derivatives thereof or synthetic polymers;
the cellulose derivative is one or more of methyl cellulose, ethyl cellulose, isopropyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose and carboxymethyl ethyl cellulose;
the synthetic polymer is one or more of polyvinyl alcohol, polyethylene glycol and polypropylene glycol.
Further, the coating material is one of a metal modified molecular sieve, a metal oxide or a metal composite oxide, and an oxide or a composite oxide which supports noble metal; the noble metal is one or more of Pt, Pd and Rh.
Further, the modified metal of the molecular sieve is one or more of Cu, Fe, Co, Ni, Ce, Ag and Mn; the molecular sieve is one or more of BEA, CHA, MFI, LTA, AEI, AFX and FAU.
Further, the metal oxide is a transition metal oxide or an alkaline earth metal oxide;
the composite oxide is one or more of cerium-zirconium composite oxide, lanthanum-aluminum composite oxide, cerium-zirconium-lanthanum-aluminum composite oxide and cerium-aluminum composite oxide.
The technical scheme provided by the embodiment of the invention has the following beneficial effects:
the invention soaks hydrophobic agent on both ends of the carrier whose end surface is not blocked, quantitatively gives slurry to the end surface of the carrier, makes the slurry of the coating evenly distributed on the wall of the carrier by negative pressure suction, after drying and roasting, uses the same mud material as the wall flow type carrier material to alternatively block the pores on the end surface of the carrier which is not blocked, and then carries out drying and sintering treatment to obtain the finished wall flow type particle trapping catalyst. The technical scheme of the invention can realize uniform distribution of the coating material on the wall-flow carrier, and effectively reduce the back pressure of the finished catalyst on the premise of ensuring the trapping rate. The pressure drop of the whole post-treatment assembly is effectively improved while the engineering application is met, and the fuel economy of the whole vehicle is improved.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The carriers of examples 1-6 and comparative examples 1-2 were cylindrical wall flow carriers of cordierite material having a diameter of 143.8mm and a height of 150.5mm, a porosity of 55%, and a coating amount of 100 g/L;
the carriers of examples 7 to 9 and comparative example 3 were cylindrical wall flow carriers of a silicon carbide material having a diameter of 143.8mm and a height of 177.8mm, and had a porosity of 60% and a coating amount of 10 g/L.
Example 1
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. preparing slurry of a CHA type copper-containing molecular sieve coating material, wherein the solid content of the slurry of the coating material is 15.0%, adding sodium silicate with the weight of 1.0% of the weight of a condensate as a dispersing agent and 0.5% of silica sol as a binder into the slurry, uniformly stirring, carrying out ball milling, adding 5.0% of methylcellulose into the slurry as a water locking agent, and stirring to form a finished slurry for later use;
b. taking a carrier with two ends not closed and plugged, soaking naphtha at the two ends, wherein the soaking height is 10mm, fixing the carrier on coating equipment, quantitatively feeding slurry on the air inlet end face of the carrier, uniformly distributing the coating slurry on the wall of the carrier by negative pressure suction, then placing the carrier in a drying oven at 150 ℃ for drying to constant weight, and roasting and cooling the coated carrier at 300 ℃ for later use;
c. alternately plugging the non-plugged ends of the carrier by using pug, drying at 120 ℃ for 3h, and sintering at 600 ℃ for 1h to obtain the finished product of the copper-based molecular sieve type wall-flow particle trapping catalyst.
Example 2
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. preparing slurry of a CHA type copper-containing molecular sieve coating material, wherein the solid content of the slurry of the coating material is 15.0%, adding sodium silicate with the weight of 1% of the cured material as a dispersing agent and 0.5% of silica sol as a binder into the slurry, uniformly stirring, carrying out ball milling, adding 5.0% of methylcellulose as a water locking agent into the slurry, and stirring to form finished slurry for later use;
b. taking a pore-plugging carrier with an unclosed air inlet end, infiltrating naphtha into two end faces, wherein the infiltration height is 10mm, fixing the pore-plugging carrier on coating equipment, quantitatively feeding slurry onto the air inlet end face of the carrier, uniformly distributing the coating slurry on the wall of the carrier by negative pressure suction, then placing the carrier in a 120 ℃ oven for drying to constant weight, and roasting and cooling the coated carrier at 400 ℃ for later use;
c. alternately plugging the non-plugged ends of the carrier by using pug, drying at 120 ℃ for 3h, and sintering at 600 ℃ for 1h to obtain the finished product of the copper-based molecular sieve type wall-flow particle trapping catalyst.
Example 3
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. preparing slurry of a CHA type copper-containing molecular sieve coating material, wherein the solid content of the slurry of the coating material is 15.0%, adding sodium silicate with the weight of 1.0% of the weight of a condensate as a dispersant into the slurry, taking 0.5% of silica sol as a binder, uniformly stirring, carrying out ball milling, adding 5.0% of methylcellulose as a water locking agent into the slurry, and stirring to form finished slurry for later use;
b. taking a pore-plugging carrier with an unclosed air outlet end, infiltrating naphtha into two end faces, wherein the infiltration height is 10mm, fixing the pore-plugging carrier on coating equipment, quantitatively feeding slurry onto the air outlet end face of the carrier, uniformly distributing the coating slurry on the wall of the carrier through negative pressure suction, then placing the carrier in a 150 ℃ oven to dry to constant weight, repeating the steps, coating an air inlet end, and roasting and cooling the coated carrier at 300 ℃ for later use;
c. alternately plugging the non-plugged ends of the carrier by using pug, drying at 120 ℃ for 3h, and sintering at 600 ℃ for 1h to obtain the finished product of the copper-based molecular sieve type wall-flow particle trapping catalyst.
Example 4
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. the prepared precious metal Rh has the loading of 5g/ft3The first slurry of the cerium-zirconium-aluminum composite oxide with the solid content of 35.0 percent, wherein the cerium-zirconium-aluminum composite oxide comprises the following components in percentage by mass: 25% of CeO245% ZrO230% of Al2O3；
The prepared noble metal Pd loading capacity is 15g/ft3And the second slurry of the cerium-zirconium-lanthanum-aluminum composite oxide with the solid content of 25.0 percent, wherein the components of the cerium-zirconium-lanthanum-aluminum composite oxide in percentage by mass comprise: 25% of CeO245% ZrO25% of La2O3And 25% of Al2O3Sodium citrate as a dispersant in an amount of 3.0% by weight of the cured product was added to the first slurry, and the cured product wasTaking silicon-aluminum composite sol with the weight of 1.0 percent as a binder, taking hydroxyethyl cellulose with the weight of 0.5 percent of cured material as a water locking agent, and stirring to form finished slurry for later use; adding sodium citrate with the weight of 2.0% of the weight of the cured substance into the second slurry as a dispersing agent, adding silicon-aluminum composite sol with the weight of 1.0% of the weight of the cured substance as a binder, and adding hydroxyethyl cellulose with the weight of 1.0% of the weight of the cured substance as a water locking agent, and stirring to form a finished slurry for later use;
b. taking a pore-plugging carrier with an unsealed gas inlet end and a unsealed gas outlet end, infiltrating naphtha into the two end faces, wherein the infiltration height is 10mm, fixing the carrier on coating equipment, quantitatively feeding first slurry on the gas inlet end face, uniformly distributing the coating slurry on the wall of the carrier by negative pressure suction, and then placing the carrier in a 150 ℃ oven to dry the carrier to constant weight. Repeating the steps, coating the second slurry on the air inlet end, and then roasting and cooling at 300 ℃ for standby;
c. alternately plugging the non-plugged ends of the carrier by using pug, wherein the plugging depth is 5mm, drying at 150 ℃ for 1h, and sintering at 400 ℃ for 3h to obtain the finished wall-flow type particle trapping catalyst.
Example 5
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. the prepared precious metal Rh has the loading of 5g/ft3The first slurry of the cerium-zirconium-aluminum composite oxide with the solid content of 35.0 percent, wherein the cerium-zirconium-aluminum composite oxide comprises the following components in percentage by mass: 25% of CeO245% ZrO230% of Al2O3；
The prepared noble metal Pd loading capacity is 15g/ft3And the second slurry of the cerium-zirconium-lanthanum-aluminum composite oxide with the solid content of 25.0 percent, wherein the components in the cerium-zirconium-lanthanum-aluminum composite oxide comprise the following components in percentage by mass: 25% of CeO245% ZrO25% of La2O3And 25% of Al2O3Adding sodium citrate as dispersant in 3.0 wt% of the cured matter, composite silica-alumina sol as adhesive in 1.0 wt% of the cured matter and hydroxyethyl cellulose as water locking agent in 0.5 wt% of the cured matter into the first slurry, and stirring to formThe finished slurry is ready for use; adding sodium citrate accounting for 2.0 percent of the weight of the cured substance into the second slurry as a dispersing agent, silicon-aluminum composite sol accounting for 1.0 percent of the weight of the cured substance as a binder, and hydroxyethyl cellulose accounting for 1.0 percent of the weight of the cured substance as a water locking agent, and stirring to form a finished product slurry for later use;
b. taking a pore-plugging carrier with an unclosed air inlet end, soaking naphtha into the double end faces with the soaking height of 10mm, fixing the pore-plugging carrier on coating equipment, quantitatively feeding first slurry onto the air inlet end face, uniformly distributing the coating slurry on the wall of the carrier through negative pressure suction, and then placing the carrier in a 120 ℃ oven for drying to constant weight. Repeating the steps, coating the second slurry on the air inlet end, and then roasting and cooling at 400 ℃ for standby;
c. alternately plugging the non-plugged ends of the carrier by using pug, wherein the plugging depth is 5mm, drying at 150 ℃ for 1h, and sintering at 400 ℃ for 3h to obtain the finished wall-flow type particle trapping catalyst.
Example 6
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. the loading amount of the prepared precious metal Rh is 5g/ft3The first slurry of the cerium-zirconium-aluminum composite oxide with the solid content of 35.0 percent, wherein the cerium-zirconium-aluminum composite oxide comprises the following components in percentage by mass: 25% of CeO245% ZrO230% of Al2O3；
The loading capacity of the prepared noble metal Pd is 15g/ft3And the second slurry of the cerium-zirconium-lanthanum-aluminum composite oxide with the solid content of 25.0 percent, wherein the components in the cerium-zirconium-lanthanum-aluminum composite oxide comprise the following components in percentage by mass: 25% of CeO245% ZrO25% of La2O3And 25% of Al2O3Adding sodium citrate with the weight of 3.0% of the weight of the cured material as a dispersing agent, silicon-aluminum composite sol with the weight of 1.0% of the weight of the cured material as a binder and hydroxyethyl cellulose with the weight of 0.5% of the weight of the cured material as a water locking agent into the first slurry, and stirring to form a finished slurry for later use; sodium citrate as a dispersant in an amount of 2.0% by weight of the cured product and silicon in an amount of 1.0% by weight of the cured product were added to the second slurryTaking the aluminum composite sol as a binder, taking hydroxyethyl cellulose with the weight of 1.0 percent of the weight of the cured substance as a water locking agent, and stirring to form a finished slurry for later use;
b. taking a carrier with an air outlet end not blocked with pores, soaking naphtha into the two end faces, wherein the soaking height is 10mm, fixing the carrier on coating equipment, quantitatively feeding second slurry onto the air outlet end face, uniformly distributing the coating slurry on the wall of the carrier through negative pressure suction, and then placing the carrier in an oven at 150 ℃ for drying until the weight is constant; repeating the steps, coating the first slurry on the gas outlet end, and then roasting and cooling at 300 ℃ for standby;
c. alternately plugging the non-plugging ends of the carrier by using pug, wherein the plugging depth is 5mm, drying the carrier at 150 ℃ for 1h, and sintering the carrier at 400 ℃ for 3h to obtain the finished wall-flow type particle trapping catalyst.
Example 7
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. the loading capacity of the prepared precious metal Pt is 4g/ft3Pd loading amount of 1g/ft3The slurry of the cerium-aluminum composite oxide with the solid content of 35.0 percent, wherein the cerium-aluminum composite oxide comprises the following components in percentage by mass: 30% of CeO270% of Al2O3Adding isopropanolamine accounting for 3.0 percent of the weight of the cured substance into the slurry as a dispersing agent, alumina sol accounting for 2.0 percent of the weight of the cured substance as a binder and hydroxyethyl cellulose accounting for 0.5 percent of the weight of the cured substance as a water locking agent, and stirring to form finished slurry for later use; wherein the loading of Pt is 4g/ft3The supported amount of Pd is 1g/ft3；
b. Taking a pore-plugging carrier with an unsealed gas inlet end and a unsealed gas outlet end, infiltrating naphtha into two end faces, wherein the infiltration height is 10mm, fixing the pore-plugging carrier on coating equipment, quantitatively feeding slurry onto the gas inlet end face, uniformly distributing the coating slurry on the wall of the carrier by negative pressure suction, then placing the carrier in a 150 ℃ oven to dry the carrier to constant weight, and then roasting and cooling the carrier at 300 ℃ for standby;
c. alternately plugging the non-plugged ends of the carrier by using pug, wherein the plugging depth is 5mm, drying at 130 ℃ for 2h, and sintering at 600 ℃ for 1h to obtain the finished wall-flow type particle trapping catalyst.
Example 8
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. the loading capacity of the prepared precious metal Pt is 4g/ft3Pd loading amount of 1g/ft3The slurry of the cerium-aluminum composite oxide with the solid content of 35.0 percent, wherein the cerium-aluminum composite oxide comprises the following components in percentage by mass: 30% of CeO270% of Al2O3Adding isopropanolamine accounting for 3.0 percent of the weight of the cured substance into the slurry as a dispersing agent, alumina sol accounting for 2.0 percent of the weight of the cured substance as a binder and hydroxyethyl cellulose accounting for 0.5 percent of the weight of the cured substance as a water locking agent, and stirring to form finished slurry for later use;
b. taking a pore-plugging carrier with an unclosed air inlet end, infiltrating naphtha into two end faces, wherein the infiltration height is 10mm, fixing the pore-plugging carrier on coating equipment, quantitatively feeding slurry onto the air inlet end face, uniformly distributing the coating slurry on the wall of the carrier through negative pressure suction, then placing the carrier in a 150 ℃ oven to dry to constant weight, and then roasting and cooling at 300 ℃ for later use;
c. alternately plugging the non-plugged ends of the carrier by using pug, wherein the plugging depth is 5mm, drying at 130 ℃ for 2h, and sintering at 600 ℃ for 1h to obtain the finished wall-flow type particle trapping catalyst.
Example 9
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. the loading capacity of the prepared precious metal Pt is 4g/ft3Pd loading amount of 1g/ft3The slurry of the cerium-aluminum composite oxide with the solid content of 35.0 percent, wherein the cerium-aluminum composite oxide comprises the following components in percentage by mass: 30% of CeO270% of Al2O3Adding isopropanolamine accounting for 3.0 percent of the weight of the cured substance into the slurry as a dispersing agent, alumina sol accounting for 2.0 percent of the weight of the cured substance as a binder and hydroxyethyl cellulose accounting for 0.5 percent of the weight of the cured substance as a water locking agent, and stirring to form finished slurry for later use;
b. taking a pore-plugging carrier with an unclosed air outlet end, infiltrating naphtha into two end faces, wherein the infiltration height is 10mm, fixing the pore-plugging carrier on coating equipment, quantitatively feeding slurry onto the air outlet end face, uniformly distributing the coating slurry on the wall of the carrier through negative pressure suction, then placing the carrier in a 150 ℃ oven to dry to constant weight, and then roasting and cooling at 300 ℃ for later use;
c. alternately plugging the non-plugged ends of the carrier by using pug, wherein the plugging depth is 5mm, drying at 130 ℃ for 2h, and sintering at 600 ℃ for 1h to obtain the finished wall-flow type particle trapping catalyst.
Comparative example 1
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. preparing slurry of a CHA type copper-containing molecular sieve coating material, wherein the solid content of the slurry of the coating material is 15.0%, adding sodium silicate accounting for 1.0% of the weight of cured materials into the slurry as a dispersing agent and silica sol accounting for 0.5% of the weight of the cured materials into the slurry as a binder, uniformly stirring, carrying out ball milling, adding methylcellulose accounting for 5.0% of the weight of the cured materials into the slurry as a water locking agent, and stirring to form finished slurry for later use;
b. taking a pore-plugging carrier with two ends alternately sealed, infiltrating naphtha into the two ends, wherein the infiltration height is 10mm, fixing the pore-plugging carrier on coating equipment, quantitatively feeding slurry onto an air inlet end face, uniformly distributing the coating slurry on the wall of the carrier by negative pressure suction, and then placing the carrier in a 150 ℃ oven to dry the carrier to constant weight; repeating the steps, coating the air outlet end, and then roasting and cooling the coated carrier at 300 ℃ for standby;
c. alternately plugging the non-plugged ends of the carrier by using pug, drying at 120 ℃ for 3h, and sintering at 600 ℃ for 1h to obtain the finished product of the copper-based molecular sieve type wall-flow particle trapping catalyst.
Comparative example 2
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. the prepared precious metal Rh has the loading of 5g/ft3The first slurry of the cerium-zirconium-aluminum composite oxide with the solid content of 35.0 percent, wherein the components of the cerium-zirconium-aluminum composite oxide comprise the following components in percentage by massComprises the following steps: 25% of CeO245% ZrO230% of Al2O3；
The prepared noble metal Pd loading capacity is 15g/ft3And the second slurry of the cerium-zirconium-lanthanum-aluminum composite oxide with the solid content of 25.0 percent, wherein the cerium-zirconium-lanthanum-aluminum composite oxide comprises the following components in percentage by mass: 25% of CeO245% ZrO25% of La2O3And 25% of Al2O3；
Adding sodium citrate with the weight of 3.0% of the weight of the cured substance as a dispersing agent, silicon-aluminum composite sol with the weight of 1.0% of the weight of the cured substance as a binder and hydroxyethyl cellulose with the weight of 0.5% of the weight of the cured substance as a water locking agent into the first slurry, and stirring to form a finished product slurry for later use; adding sodium citrate accounting for 2.0 percent of the weight of the cured substance into the second slurry as a dispersing agent, adding silicon-aluminum composite sol accounting for 1.0 percent of the weight of the cured substance as a binder, adding hydroxyethyl cellulose accounting for 1.0 percent of the weight of the cured substance as a water locking agent, and stirring to form a finished slurry for later use;
b. taking a pore-plugging carrier with two ends alternately sealed, infiltrating naphtha into an air inlet end face, wherein the infiltration height is 10mm, fixing the pore-plugging carrier on coating equipment, quantitatively feeding first slurry onto the air inlet end face, uniformly distributing the coating slurry on the wall of the carrier by negative pressure suction, and then placing the carrier in a 150 ℃ oven to dry the carrier to constant weight; repeating the steps, coating the second slurry on the gas outlet end, and then roasting and cooling at 300 ℃ for standby;
c. alternately plugging the non-plugged ends of the carrier by using pug, wherein the plugging depth is 5mm, drying at 150 ℃ for 1h, and sintering at 400 ℃ for 3h to obtain the finished wall-flow type particle trapping catalyst.
Comparative example 3
A method of preparing a wall-flow particulate trap catalyst, comprising the steps of:
a. the loading capacity of the prepared precious metal Pt is 4g/ft3Pd loading amount of 1g/ft3The slurry of the cerium-aluminum composite oxide with the solid content of 35.0 percent, wherein the cerium-aluminum composite oxide comprises the following components in percentage by mass: 30% of CeO270% of Al2O3Adding isopropanolamine accounting for 3.0 percent of the weight of the cured substance into the slurry as a dispersing agent, alumina sol accounting for 2.0 percent of the weight of the cured substance as a binder and hydroxyethyl cellulose accounting for 0.5 percent of the weight of the cured substance as a water locking agent, and stirring to form finished slurry for later use;
b. taking a pore-plugging carrier with two ends alternately sealed, infiltrating naphtha into an air inlet end face, wherein the infiltration height is 10mm, fixing the pore-plugging carrier on coating equipment, quantitatively feeding slurry to the air inlet end face, uniformly distributing the coating slurry on the wall of the carrier by negative pressure suction, then placing the carrier in a 150 ℃ oven to dry to constant weight, repeating the steps, coating an air outlet end, and then roasting and cooling at 300 ℃ for standby;
c. alternately plugging the non-plugged ends of the carrier by using pug, wherein the plugging depth is 5mm, drying at 130 ℃ for 2h, and sintering at 600 ℃ for 1h to obtain the finished wall-flow type particle trapping catalyst.
At 25 ℃ and 600m3The cold flow back pressure values of the finished wall-flow type particle trapping catalysts and the blank supports obtained in examples 1 to 9 and comparative examples 1 to 3 were measured under the/h conditions, and the results are shown in Table 1.
TABLE 1 Cold flow Back pressure values of finished catalysts and bare supports prepared in examples 1-9 and comparative examples 1-3
Sample (I)
Blank carrier backpressure/mbar
Back pressure/mbar of finished product
Increase in amplitude/%)
Percent by capture rate%
Example 1
44.6
51.7
16.0
90.5
Example 2
44.5
51.8
16.3
91.3
Example 3
45.2
52.9
17.1
91.9
Example 4
46.6
55.0
18.1
92.4
Example 5
46.6
55.0
18.0
93.3
Example 6
46.9
55.7
18.7
93.0
Example 7
62.7
69.6
11.0
89.7
Example 8
62.5
69.4
11.1
88.9
Example 9
62.8
70.0
11.5
90.0
Comparative example 1
44.5
55.3
24.3
92.5
Comparative example 2
46.7
57.5
23.1
94.0
Comparative example 3
62.6
72.6
16.0
91.0
It can be seen from the above results that, by adopting the technical scheme of the invention, the trapping rate of the catalyst samples of examples 1-3 is equivalent to that of the sample of comparative example 1, but the increase of the back pressure is reduced by about 8%; similarly, the catalyst samples of examples 4-6 had comparable trapping rates to the sample of comparative example 2, but the backpressure increase was reduced by about 5%; the catalyst samples of examples 7-9 had comparable trapping rates to the sample of comparative example 3, but the backpressure increase was reduced by about 5%. From the comparison of the results, the technical scheme of the invention can obviously reduce the back pressure of the wall-flow type trapping catalyst on the premise of ensuring the trapping efficiency.
Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.