CN102380377B - Metal-foam structure unit for POC (particle oxidation catalyst) postprocessor - Google Patents

Abstract

The invention relates to a metal-foam structure unit for a POC (particle oxidation catalyst) postprocessor, which is characterized in that the process includes steps of firstly, removing oil of a metal-foam carrier in a high-temperature furnace; secondly, preparing suspension; thirdly, soaking the metal-foam carrier into the suspension, taking the same out of the suspension after 30-50 minutes and then drying the same in a drying box so as to obtain an undercoat carrier; and fourthly, preparing active catalyst solution and spraying the same onto the undercoat carrier to complete coating of Si-Al-Ti-Ce/Zr/Pt catalysts finally. The metal-foam structure unit for the POC postprocessor can be mounted at the front end of an SCR (selective catalytic reduction) main carrier and catalysts and used for mixing and dispersing of tail gas, promoting reaction of oxidizing NO in the tail gas into NO2, and then promoting reaction between NO2 and carbon in PM (particulate matter), thereby meeting requirements of commercial vehicles at levels of national standard IV at least. In addition, the metal-foam structure for the POC postprocessor is simple in processing, high in efficiency and low in cost.

Description

For the foamed metal structures unit of POC preprocessor

Technical field

The present invention relates to a kind of foamed metal structures unit for POC preprocessor, the post processing industry of vehicle exhaust can be applied to.

Background technology

Current, the whole world faces the integration challenges of the energy and environment.In the technological means selection of the emission compliance of orthodox car, people still face many difficult problems, such as, how to select the aspect such as carrier and catalyst of post processing.

POC post processing carrier is the key factor forming automobile-used post processing platform, and by the end of so far, in post processing carrier, the overwhelming majority is the ceramic monolith of import, and the mechanical strength of this ceramic monolith is slightly poor, is not too adapted to the actual conditions of China; Equally, ripe metallic carrier, also by external technology and patent monoply, becomes the key factor restricting Chinese post processing industry development.

Therefore, how obtaining low cost and high performance post processing carrier is the core content advancing this art progress.

The essence of POC preprocessor technology is first PM ' filtration ' or ' retaining ' get off, then be oxidized under the effect of catalyst, main component SOF partial oxidation in PM is become CO2 and H2O, PM particle size is reduced, eliminate the factor of its toxicity and harm, therefore, the essential problem that PM exceeds standard is solved.POC preprocessor can reach 50 ~ 80% to the treatment effeciency of PM, and blocked fault rate is also well below DPF.Therefore, POC is the focus of foreign study, wherein, representative with Ecocat company most.

In fact, the design of the carrier that the POC system of import is used and catalyst has strict regulation, such as, in the front end of POC main carrier and catalyst, the general carrier with DOC effect and the catalyst all installing small size additional, promote the Quick Oxidation of PM, also the NO composition in exhaust can be oxidized to NO2, to promote that the carbon in NO2 and PM reacts; For this reason, the foamed metal structures unit of POC preprocessor has the meaning of reality.

The essence of POC preprocessor is advanced carrier and the combination of catalyst technology.Wherein, carrier is the most key, not only affects performance, also affects cost and life-span.

Ecocat company POC carrier is its patented technology, and its essence is the metal honeycomb plate of structure uniqueness and the assembly of ultrafine metal fibers weaving felt.But expensive, domestic diesel vehicle can not adopt in enormous quantities.

Foam metal is a kind of physical function new engineering material integrated with architectural characteristic.Start metal foaming material development the beginning of the eighties in the world, metal foaming material possesses light weight, sound insulation, filtration and flame-retarding characteristic, has again very strong shock-absorbing and electromagnetic shielding action, therefore, is widely used in national defense industry.The 90's rose, and foam metal is applied to civilian industry, and such as, high-caliber nickel foam is applied to the preparation of industrial electric capacity and automobile super capacitance.At present, China's foam metal research and production technical merit occupy prostatitis, the world.

Analyze from structure and show with actual test, foam metal is optimal post-treating metal carrier, such as, structural strength is higher than ceramic monolith, and gas channel is disorderly, the most easily obtain the catalytic effect of anticipation, in addition, the coating of catalyst and construction technology are comparatively simple, therefore, select metal foam as carrier, possess theoretic advance; But, the disadvantage of foam metal is that price is high, average 250 ~ 350 yuan/liter, even higher, for the diesel vehicle of an engine displacement 10 liters, the volume of post processing carrier is needed to be about about 20 liters, therefore, if adopt the foam metal of 100% as carrier, only carrier part is just up to 5000 ~ 7000 yuan/car, after considering the cost of catalyst and encapsulation, just causing the cost of car load to raise cannot accept, and becomes the obstacle of foam metal application.

Therefore, the structural parameters optimizing foam metal carrier are key factors that can this material obtain batch application.

POC carrier becomes the key of POC preprocessor application.Some some ' Cellular board and its combinations ' of utilizing ultra thin high temperature resistant corrosion resistant plate to manufacture, such as, the patent No. is ' exhaust gas purifying metal carrier, use laminate exhaust gas purifying filter ' patent of ' 200810091662.9 '; The patent No. is ' manufacture method of exhaust gas purifying metal carrier, exhaust gas purifying metal carrier and exhaust emission control filter ' patent of ' 200480036580.4 '; The patent No. is ' metallic carrier of new ceramics process ' patent of ' 200410022788.2 '; ' a kind of catalyst metal carrier with alumina layer ' patent that the patent No. is ' 99101110.4 '; The patent No. is ' metal carrier catalyst for waste gas purification ' patent of ' 01111387.1 ' etc., because the mass transfer of gas and the passage of heat transfer are through or are equal to through, therefore, bad to the treatment effect of PM, POC after-treatment device cannot be applicable to.

Some patents adopt wire cross to be woven into the wire netting of plane, then these mesh sheet are stacked together, and the such as patent No. is ' met like ceramic carrier ' patent of ' 98248772.X '; The patent No. is ' met like ceramic carrier ' patent of ' 99253757.6 '; The patent No. is ' Cellulated wiremesh carrier of catalyzing and reducing nitrogen oxides ' patent of ' 200710010357.8 '; ' a kind of Cellulated wiremesh carrier with aluminum oxide coating layer and preparation method thereof ' patent that the patent No. is ' 200710010359.7 '; The patent No. is ' method of covering aluminum oxide coating on honeycomb shaped wire mesh carrier ' patent of ' 200810011365.9 '; The patent No. is ' Cellulated wiremesh carrier for purifying exhaust air ' patent of ' 200810011366.3 '; The patent No. is ' the area load nano-TiO of ' 200420094705.6 ' ₂metal screen ' patent etc., because the mass transfer of gas and the passage of heat transfer are similar to through, the degree of gas channel disorder is not high, the probability that PM particle is collided and retains is not high, therefore, bad to the treatment effect of PM, POC after-treatment device cannot be applicable to.

Some patents adopt complete foam metal as the carrier of catalyst, although solve the problems referred to above, but face the inferior position of cost, the production in enormous quantities of the automobile of domestic market cannot be applied to, but its reliability is high, need improvement carrier element being carried out to structure, when guaranteed performance, reduce costs, can be applied to the vehicle of the higher export-oriented of carrier technique, structural strength and reliability requirement, the such as patent No. is ' a kind of preparation method of high porosity metal porous carrier materials ' patent of ' 200610156330.5 '; The patent No. is ' metal carrier for automobile tail gas purifier catalyst and preparation method thereof ' patent of ' 200510024944.3 '; The patent No. is ' a kind of foam metal hydrogenating catalyst and its preparation method and application ' patent of ' 200410096609.X '; The patent No. is ' a kind of Lacunaris metal carrier and preparation method thereof ' patent of ' 200710034317.7 ' etc.

Above-mentioned existing a lot of patent, part relates to carrier and the catalyst of POC, but catalyst system is different from the present invention; Although also there is patent to describe carrier, be different from the present invention; Although also there is patent to describe the layout of carrier, be different from the present invention.

Summary of the invention

The object of the present invention is to provide a kind of foamed metal structures unit for POC preprocessor, its air-flow for tail gas mixing dispersion and promotion NO partial oxidation become the reaction of NO2, react in order to facilitate the carbon in NO2 and PM, meet the commercial car demand of state more than 4, simple process, efficiency is high, and cost is low, reduces environmental pollution.

Technical scheme of the present invention is achieved in that the foamed metal structures unit for POC preprocessor, it is characterized in that: the order number of foam metal carrier is 5 ~ 50ppi, porosity is for being greater than 80%, the foam metal that through-hole rate is greater than 90%, thickness 20 ~ 35mm, diameter is greater than gripper shoe perforate 60 ~ 90mm, and the material of foam metal is any one of foamed aluminium, nickel foam, titanium foam or stainless steel foam; Foam metal carrier is coated with the catalyst be suitable for POC operating mode, its concrete technology is as follows:

(1) overall for foam metal in high temperature furnace, heat up 450 ~ 550 DEG C and be incubated 40 ~ 60min with stove, complete removal operation;

(2) at Ludox (the SiO2 content 25.0 ~ 26.0% that 1000g is commercially available, Na2O content≤0.3%, pH value 8.5 ~ 10.0, average grain diameter is 10 ~ 20 nm) in add 400 ~ 500g average grain diameter be 5 ~ 10 nm nano titanium oxide, the deionized water of 500 ~ 600g and the alcohol of 100 ~ 200g, active oxidation aluminium powder (γ-Al2O3) 300 ~ 400g, magnesia 10 ~ 20g, calcium oxide 20 ~ 35g, after stirring, ball milling 20min becomes suspension;

(3) foam metal carrier is immersed, takes out after 30 ~ 50min, compressed air purges unnecessary liquid, and ambient temperatare puts 24h, then purges the liquid of trickling with compressed air;

(4) put into drying box, heat up 80 DEG C in proper order, insulation 60min, and then be warmed up to 400 ~ 480 DEG C, 100 ~ 120min is as the carrier completing inter coat in insulation;

(5) in 1000 ml of distilled water to add 12 ~ 25% cerium nitrate, 20-35% of zirconium nitrate, 0.5 ~ 2% nitric acid platinum, 3 ~ 10% and 0.1 ~ 0.5% nitric acid alcohol, stir to dissolve as the active catalyst solution;

(6) active catalyst solution has been sprayed on the carrier of inter coat, two sides sprays, to not trickling, ambient temperatare moves into 50 DEG C of insulation 20min in drying box after putting 120 ~ 300min, 40min is incubated at 80 DEG C, be incubated 100min at 150 DEG C, at 450 DEG C, be incubated 200min, cool with stove; Form Si-Al-Ti-Ce/Zr/Pt catalyst.

Good effect of the present invention is: start with from optimization foam metal effect and structure, adopts the active catalyst of low precious metal content, completes the making of foamed metal structures unit, have very high practical value.

Accompanying drawing explanation

Fig. 1 is the velocity contrast that carbon granule of the present invention carries out with NO2 and oxygen reacting.

Detailed description of the invention

Further describe the present invention below by embodiment, embodiment, for illustrate feature of the present invention further, is not equal to restriction the present invention, for the change that those skilled in the art carries out according to the present invention, all should be included within protection scope of the present invention.

embodiment 1

Choose commercially available foam metal carrier, material is foamed aluminium, and order number is 5ppi[hole count per square inch], porosity for being greater than 80%, the foam metal that through-hole rate is greater than 90%, thickness 35mm, diameter is greater than gripper shoe perforate 60mm, diameter is 380mm, bores supported hole 6, uniform, overall for foam metal in high temperature furnace, heat up 450 DEG C and be incubated 60min with stove, complete removal operation, weigh W1=750g.Be immersed by foam metal carrier, take out after 20min, compressed air purges unnecessary liquid, and ambient temperatare puts 24h, then purges the liquid of trickling with compressed air; Put into drying box, heat up 80 DEG C in proper order, insulation 60min; And then be warmed up to 350 DEG C, insulation 120min; As the foam metal carrier completing inter coat; Weigh W3=778g;

Commercially available in 1000 g of colloidal silica (SiO2 content of 25.0 ~ 26.0%, the content of Na2O 0.3% or less, PH 8.5 ~ 10.0, the average particle size is 10 ~ 20 nm) the average particle size of joining an extra 500 g for 5 ~ 10 nm nano titanium dioxide 500 g, 500 g of deionized water and alcohol, activated alumina powder (gamma - Al2O3), 400 g, 10 g of magnesium oxide, calcium oxide, 20 g stirred ball mill after 20 min into slurry;In 1000 ml of distilled water to join an extra 150 g 300 g of cerium nitrate, nitric acid zirconium, 10 g of platinum nitrate, 100% alcohol and 2 g nitrate, stir to dissolve as the active catalyst solution;

Active catalyst solution is sprayed on the foam metal carrier of the inter coat completing aforesaid operations, two sides sprays, after ambient temperatare puts 120min, move in drying box, 50 DEG C of insulation 20min, are incubated 40min at 80 DEG C, are incubated 100min at 150 DEG C, be incubated 200min at 450 DEG C, cool with stove; Form Si-Al-Ti-Ce/Zr/Pt catalyst.Weigh W5=781g;

Choose thickness be the metallic plate of 2mm stainless steel through the operation such as flange, punching, make metal profile, gripper shoe opening diameter 320mm; The metallic plate choosing thickness 3mm stainless steel prepares metallic support sheet after the operation such as bending, punching, one end welding of support chip on the supporting plate, get the foam metal carrier after coating catalyst 2, adopt set bolt to be fixed on 2 sides of gripper shoe, complete the making of foamed metal structures unit; The front end of the original POC preprocessor on state 3 diesel engine of certain 9L, install foam metal unit of the present invention, carry out engine bench test, result shows, under different operating mode, back pressure raises and is less than 1Kpa, and PM clearance (smoke intensity target improvement) improves 11 ~ 19%.

embodiment 2

Choose commercially available foam metal carrier, material is nickel foam, and order number is 35ppi[hole count per square inch], porosity for being greater than 80%, the foam metal that through-hole rate is greater than 90%, thickness 25mm, diameter is greater than gripper shoe perforate 60mm, diameter is 380mm, bores supported hole 6, uniform, overall for foam metal in high temperature furnace, heat up 550 DEG C and be incubated 40min with stove, complete removal operation, weigh W2=821g.

Foam metal carrier in among them, take out after 50 min, compressed air purge excess liquid, 24 h at room temperature, with compressed air purging flowing liquid.In the drying oven, progressive temperature 80 ℃, insulation 60 min;Then heat up to 400 ℃, 100 min insulation;As a carrier of complete intermediate coating;Weighing W4 = 921 g;Commercially available in 1000 g of colloidal silica (SiO2 content of 25.0 ~ 26.0%, the content of Na2O 0.3% or less, PH 8.5 ~ 10.0, the average particle size is 10 ~ 20 nm) the average particle size of joining an extra 500 g for 5 ~ 10 nm nano titanium dioxide 500 g, 500 g of deionized water and alcohol, activated alumina powder (gamma - Al2O3), 400 g, 10 g of magnesium oxide, calcium oxide, 20 g stirred ball mill after 20 min into slurry;In 1000 ml of distilled water to join an extra 150 g 300 g of cerium nitrate, nitric acid zirconium, 10 g of platinum nitrate, 100% alcohol and 2 g nitrate, stir to dissolve as the active catalyst solution;

Active catalyst solution is sprayed on the foam metal carrier of above-mentioned inter coat, two sides sprays, after ambient temperatare puts 300min, move in drying box, 50 DEG C of insulation 20min, are incubated 40min at 80 DEG C, be incubated 100min at 150 DEG C, at 450 DEG C, be incubated 200min, cool with stove; Form Si-Al-Ti-Ce/Zr/Pt catalyst.Weigh W6=922g;

Choose thickness be the metallic plate of 2mm stainless steel through the operation such as flange, punching, make metal profile, gripper shoe opening diameter 320mm; The metallic plate choosing thickness 3mm stainless steel prepares metallic support sheet after the operation such as bending, punching, one end welding of support chip on the supporting plate, get the foam metal carrier after coating catalyst 2, adopt set bolt to be fixed on 2 sides of gripper shoe, complete the making of foamed metal structures unit; The front end of the original POC preprocessor on state 3 diesel engine of certain 9L, install foam metal unit of the present invention, carry out engine bench test, result shows, raise without back pressure, under different operating mode, PM clearance (smoke intensity target improvement) improves 4 ~ 7%;

embodiment 3

Adopt foam metal carrier to be 35ppi[hole count per square inch by order number] titanium foam, porosity for being greater than 80%, the foam metal that through-hole rate is greater than 90%, thickness 25mm, diameter is greater than gripper shoe perforate 70mm; Concrete technique is as follows:

(1) overall for foam metal in high temperature furnace, heat up 450 ~ 550 DEG C and be incubated 40 ~ 60min with stove, complete removal operation;

(2) at Ludox (the SiO2 content 26.0% that 1000g is commercially available, Na2O content≤0.3%, pH value 8.5, average grain diameter is 10 nm) in add 400g average grain diameter be the alcohol of the nano titanium oxide of 5 nm, the deionized water of 500g and 100g, active oxidation aluminium powder (γ-Al2O3) 300g, magnesia 10g, calcium oxide 20g, after stirring, ball milling 20min becomes suspension;

(3) foam metal carrier is immersed, takes out after 30min, compressed air purges unnecessary liquid, and ambient temperatare puts 24h, then purges the liquid of trickling with compressed air;

(4) put into drying box, heat up 80 DEG C in proper order, insulation 60min, and then be warmed up to 400 DEG C, 100min is as the carrier completing inter coat in insulation;

(5) in 1000 ml of distilled water to add 12% cerium nitrate, 20% of platinum zirconium nitrate, nitric acid of 0.5%, 3% ethanol and 0.1% nitric acid, stir to dissolve as the active catalyst solution;

(6) active catalyst solution has been sprayed on the carrier of inter coat, two sides sprays, to not trickling, ambient temperatare moves into 50 DEG C of insulation 20min in drying box after putting 120min, be incubated 40min, be incubated 100min at 150 DEG C at 80 DEG C, be incubated 200min at 450 DEG C, cool with stove; Form Si-Al-Ti-Ce/Zr/Pt catalyst.

The object adding nano titanium oxide is the specific area increasing coating, in view of the particle size of active oxidation aluminium powder is ' micron order ', add the roughness of the space multistory of film after this active oxidation aluminium powder adds immediately, namely improve the architectural characteristic in hole from another one aspect; In articulamentum of the present invention, specially add a certain amount of magnesia and calcium oxide, think based on testing inspection result and theory analysis, magnesia and calcium oxide can form stronger covalent bond with the hydroxyl in Ludox at a certain temperature jointly, under the action of heat after dehydration, jointly be deposited on the surface of carrier, form more firmly articulamentum.

The target handling object of active catalyst system of the present invention is PM, and therefore, the principal character of foamed metal structures unit of the present invention is coated with the catalyst be suitable for POC operating mode at foam metal carrier.And eliminate the NOX of part in the conceived case.

Well-known reason, in the exhaust of engine, in NOX atmosphere, the ratio of NO reaches more than 90%, NO2 about only 8%, Chemical Kinetics shows, the reaction speed of O2 and C is slow, and required temperature is higher, and the reaction speed of NO2 and C is fast, required temperature is lower, reaction icon following (Johnson Matthey Co).Can find out in Fig. 1, the temperature that NO2 carries out reacting with the carbon in PM reduces nearly 300 DEG C, and therefore, the concentration of suitable raising NO2 can improve the whole removing of PM greatly except speed and effect.

In configuration active catalyst solution, the present invention USES a water soluble nitrate, acetic acid salt, may also be an oxalate or chloride, according to the measurement and calculation, cerium zirconium near 1:2 can get the best secondary oxidation effect, although the cerium zirconium and relatively cheap, but it should be taken into account for the amount of the quality of the coating/thickness and wanted to determine the degree of oxidation reaction, the amount is too low, oxidizing relatively weak;On the contrary, the amount is too large, strong oxidizing, by-products too much;And platinum addition amount should be more strict control, to a certain space velocity and temperature field of the carrier and structure, as far as possible the amount of platinum optimization, the less the better, more conducive to cost control, though the relative to the carrier for the amount of foreign recommended platinum is 4.5 g/L, but, in the face of high sulfur content fuel, platinum concentration is too large, the rate of poisoning and faster.

Active catalyst solution spraying of the present invention to finish on intermediate coating metal foam carrier, spray on both sides. So far not flowing placed 120 ~ 300 min at room temperature to 50 ℃ in the drying oven heat preservation after 20 min, 40 min under 80 ℃ heat preservation, insulation under 150 ℃, 100 min, 450 min under 450 ℃ heat preservation, along with the furnace cooling,Formation of Si - Al - Ti - Ce/Zr/Pt catalyst, according to the activity of the solution, the proportion of consumption, measuring the platinum content is between 0.09 ~ 0.22 g/L.

Claims (1)

1. for the foamed metal structures unit of POC preprocessor, it is characterized in that: the order number of foam metal carrier (1) is 5 ~ 50ppi, porosity is for being greater than 80%, the foam metal that through-hole rate is greater than 90%, thickness 20 ~ 35mm, diameter is greater than gripper shoe perforate 60 ~ 90mm, and the material of foam metal is any one of foamed aluminium, nickel foam, titanium foam or stainless steel foam;

(1) is coated with the catalyst being applicable to POC operating mode to foam metal carrier, and its concrete technology is as follows:

(1) overall for foam metal in high temperature furnace, heat up 450 ~ 550 DEG C and be incubated 40 ~ 60min with stove, complete removal operation;

(2) at the SiO that 1000g is commercially available ₂content 25.0 ~ 26.0%, Na ₂o content≤0.3%, pH value 8.5 ~ 10.0, the alcohol of average grain diameter to be the average grain diameter adding 400 ~ 500g in the Ludox of 10 ~ 20 nm the be nano titanium oxide of 5 ~ 10 nm, the deionized water of 500 ~ 600g and 100 ~ 200g, active oxidation aluminium powder γ-Al ₂o ₃300 ~ 400g, magnesia 10 ~ 20g, calcium oxide 20 ~ 35g, after stirring, ball milling 20min becomes suspension;

(3) foam metal carrier is immersed, takes out after 30 ~ 50min, compressed air purges unnecessary liquid, and ambient temperatare puts 24h, then purges the liquid of trickling with compressed air;

(4) put into drying box, heat up 80 DEG C in proper order, insulation 60min, and then be warmed up to 400 ~ 480 DEG C, 100 ~ 120min is as the carrier completing inter coat in insulation;

(5) add in 1000mL distilled water the cerous nitrate of 12 ~ 25%, 20 ~ 35% zirconium nitrate, the platinum nitrate of 0.5 ~ 2%, the alcohol of 3 ~ 10% and 0.1 ~ 0.5% nitric acid, stirring and dissolving is as active catalyst solution;

(6) active catalyst solution has been sprayed on the carrier of inter coat, two sides sprays, to not trickling, ambient temperatare moves into 50 DEG C of insulation 20min in drying box after putting 120 ~ 300min, 40min is incubated at 80 DEG C, be incubated 100min at 150 DEG C, at 450 DEG C, be incubated 200min, cool with stove; Form Si-Al-Ti-Ce/Zr/Pt catalyst.