Sulfur-tolerant catalyst for post-treatment of methanol engine as well as preparation method and application of sulfur-tolerant catalyst

Abstract

The invention relates to a methanol engine post-treatment sulfur-tolerant catalyst and a preparation method and application thereof.The sulfur-tolerant catalyst comprises a substrate, a first active layer and a second active layer, the first active layer and the second active layer are arranged on the substrate, and the first active layer comprises a first carrier and a first active component loaded on the first carrier; the second active layer comprises a second carrier and a second active component loaded on the second carrier; the first active component is prepared from MoS2, MnS or CoS; the second active component comprises noble metal and / or non-noble metal. According to the invention, through the mutual synergistic effect of the MoS2, MnS or CoS active component in the first active layer and the noble metal and / or non-noble metal active component in the second active layer, the sulfur resistance of the catalyst is realized, the sulfur poisoning risk of the catalyst is reduced, the emission of NO2 is reduced, and the purification of pollutants such as CO, hydrocarbon, methanol, formaldehyde and the like is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a sulfur-resistant catalyst for methanol engine post-treatment, a preparation method thereof, and applications thereof. Background Art

[0002] Currently, the traditional methanol production process may contain a certain amount of impurities due to raw materials and process factors, such as sulfide mercaptans (RSH), sulfides (RSR), disulfides (RSSR), and metal impurities such as Fe, Cu, Zn, and Ni. The catalysts used in the methanol production process are prone to sulfur poisoning, mainly due to the adsorption of sulfur dioxide, oxidation to sulfate, and deposition of sulfate, which leads to the coverage of catalyst active sites and destruction of the catalyst structure. To address this phenomenon, existing technologies often modify the catalyst structure and composition to inhibit the adsorption of sulfur dioxide, promote its desorption, inhibit the formation of sulfate, and promote its decomposition, thereby improving the catalyst's sulfur resistance.

[0003] CN108472588A discloses an oxidation catalyst capable of capturing phosphorus-containing impurities and / or sulfur-containing impurities in exhaust gas generated by a diesel engine. The capturing material is a molecular sieve loaded with iron, copper, nickel, and combinations thereof; the catalytic material is a precious metal loaded on a refractory oxide, the precious metals including platinum, palladium, and a combination of platinum and palladium; the refractory oxide is alumina, silica, silica-alumina, or titania; the capturing area is in the front and preferentially contacts the exhaust gas, capturing the phosphorus-containing or sulfur-containing impurities and avoiding the influence of phosphorus / sulfur on the catalytic material.

[0004] CN109789403A discloses a diesel oxidation catalyst having a capture area for sulfur-containing impurities. The capture material is a metal and a refractory oxide that reacts with sulfur oxides in the exhaust gas. The metal is a metal selected from palladium, magnesium, cerium, and a combination of any two or more with an average particle size ≥10 nm. The refractory oxide is alumina with a specific surface area ≤50 m2 / g. The catalytic material is a refractory oxide loaded with platinum, palladium, and a combination of platinum and palladium.

[0005] Existing anti-sulfurization methods for engine aftertreatment rely on the creation of sacrificial sites, where sacrificial active materials react with sulfur species to achieve this goal. These sulfur species are captured by the sacrificial sites, minimizing coverage of the catalyst's active sites and damage to the catalyst structure. However, the sacrificial layer has no effect on exhaust gas purification and is only used to treat sulfur-containing species. This carries the risk of the catalyst losing its anti-sulfur properties due to depletion of the sacrificial layer.

[0006] Therefore, there is an urgent need to develop a catalyst with excellent sulfur resistance and the ability to reduce NO2 emissions and purify pollutants such as CO, hydrocarbons, methanol, and formaldehyde. Summary of the Invention

[0007] To address the above technical issues, the present invention provides a sulfur-tolerant catalyst for methanol engine aftertreatment, as well as its preparation method and application. Through the synergistic effect of the MoS2, MnS, or CoS active components in the first active layer and the precious metal and / or non-precious metal active components in the second active layer, the catalyst achieves sulfur resistance, reduces the risk of sulfur poisoning, reduces NO2 emissions, and improves the purification of pollutants such as CO, hydrocarbons, methanol, and formaldehyde.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a sulfur-tolerant catalyst for methanol engine post-treatment, the sulfur-tolerant catalyst comprising a substrate and a first active layer and a second active layer disposed on the substrate, the first active layer comprising a first carrier and a first active component supported on the first carrier, the second active layer comprising a second carrier and a second active component supported on the second carrier;

[0010] The first active component includes any one of MoS2, MnS or CoS or a combination of at least two thereof; the second active component includes a noble metal and / or a non-noble metal.

[0011] The sulfur-resistant catalyst for methanol engine post-treatment provided by the present invention is provided with two active layers on a substrate. The first active layer adopts MoS2, MnS or CoS as the first active component, effectively inhibiting the poisoning of the second active component by sulfide impurities in the methanol engine fuel (gray methanol), reducing the risk of catalyst sulfur poisoning, and the first active component can convert NO2 into NO, reducing the proportion of NO2 in the exhaust gas, and avoiding the harm of NO2 emissions to the environment and human health; the second active layer adopts precious metals and / or non-precious metals as the second active component, effectively reducing the concentration of NO2, CO, hydrocarbons (HC), methanol, and formaldehyde in the exhaust pollutants, thereby achieving purification of pollutants. The present invention has excellent sulfur resistance and can reduce NO2 emissions and purify pollutants such as CO, HC, methanol, and formaldehyde through the mutual synergistic effect of the first active component in the first active layer and the second active component in the second active layer.

[0012] Preferably, the arrangement of the first active layer and the second active layer on the substrate includes any one of method 1 and method 2; method 1 includes: the first active layer and the second active layer are stacked on the substrate; method 2 includes: the first active layer and the second active layer are arranged side by side on the substrate.

[0013] Preferably, the first mode specifically includes: the second active layer is provided on the surface of the substrate, and the first active layer is provided on the surface of the second active layer away from the substrate.

[0014] Preferably, the second mode specifically includes: the first active layer is arranged at the air inlet end of the first surface of the substrate, and the second active layer is arranged at the air outlet end of the first surface of the substrate.

[0015] In the present invention, the "inlet end of the first surface of the substrate" refers to the inlet area where the reactants first contact the catalyst during the post-treatment process of the methanol engine, that is, the end that enters the catalyst; the "outlet end of the first surface of the substrate" refers to the outlet area where the reaction products leave the catalyst during the post-treatment process of the methanol engine.

[0016] Preferably, in the first method, with the direction perpendicular to the surface of the substrate as the vertical direction, the ratio of the thickness of the first active layer to the second active layer in the vertical direction is 1:(1-5), for example, 1:1.0, 1:1.5, 1:2.0, 1:2.5, 1:3.0, 1:3.5, 1:4.0, 1:4.5 or 1:5.0, etc.

[0017] Preferably, in the first embodiment, a direction parallel to the surface of the substrate is defined as a horizontal direction, and areas of the first active layer and the second active layer in the horizontal direction are equal.

[0018] Preferably, in the first method, the direction perpendicular to the surface of the substrate is taken as the vertical direction, and the thickness ratio of the first active layer and the substrate in the vertical direction is 1:(0.5-1.5), for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, etc.

[0019] Preferably, in the second embodiment, a direction parallel to the first surface of the substrate is taken as a horizontal direction, and the first active layer and the second active layer are connected to each other in the horizontal direction.

[0020] Preferably, in the second method, with the direction parallel to the first surface of the substrate as the horizontal direction, the area ratio of the first active layer and the second active layer in the horizontal direction is 1:(1-5), for example, 1:1.0, 1:1.5, 1:2.0, 1:2.5, 1:3.0, 1:3.5, 1:4.0, 1:4.5 or 1:5.0, etc.

[0021] Preferably, in the second manner, a direction perpendicular to the first surface of the substrate is taken as a vertical direction, and the thicknesses of the first active layer and the second active layer in the vertical direction are equal.

[0022] Preferably, in the second method, with the direction perpendicular to the first surface of the substrate as the vertical direction, the thickness ratio of the first active layer to the substrate in the vertical direction is 1:(0.5-1.5), for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, etc.

[0023] Preferably, in the sulfur-resistant catalyst, the loading amount of the first active layer is 20-500 g / L, for example, 20 g / L, 50 g / L, 100 g / L, 150 g / L, 200 g / L, 250 g / L, 300 g / L, 350 g / L, 400 g / L, 450 g / L or 500 g / L, etc., preferably 100-400 g / L.

[0024] In the present invention, the “loading amount” refers to the ratio of the total mass of the active layer to the volume of the substrate in the sulfur-tolerant catalyst.

[0025] Preferably, in the sulfur-tolerant catalyst, the concentration of the first active component of the first active layer is 100-2000 g / ft 3 , for example 100g / ft 3 , 200g / ft 3 、300g / ft 3 , 400g / ft 3 , 500g / ft 3 、600g / ft 3 , 700g / ft 3 , 800g / ft 3 , 900g / ft 3 , 1000g / ft 3 、1100g / ft 3 , 1200g / ft 3 、1300g / ft 3 、1400g / ft 3 、1500g / ft 3 、1600g / ft 3 、1700g / ft 3 、1800g / ft 3 、1900g / ft 3 or 2000g / ft 3 etc., preferably 300-1000g / ft 3 .

[0026] In the present invention, the "concentration of active components" refers to the ratio of the mass of active components to the volume of the substrate in the sulfur-tolerant catalyst.

[0027] Preferably, in the sulfur-tolerant catalyst, the first carrier comprises a metal oxide or a metal oxide doped with a doping element.

[0028] Preferably, the metal oxide includes any one or a combination of at least two of molybdenum oxide, titanium oxide, cerium oxide, tungsten oxide, magnesium oxide, aluminum oxide, zirconium oxide, cobalt oxide, nickel oxide, niobium oxide, indium oxide, tin oxide, zinc oxide or copper oxide.

[0029] Preferably, the doping element includes any one or a combination of at least two of strontium, titanium, zirconium, niobium, iron, zinc, silver, samarium, europium, lithium, sodium, potassium, cesium, calcium, barium, magnesium, vanadium, chromium, neodymium, praseodymium, yttrium or lanthanum.

[0030] Preferably, the mass percentage of the doping element to the metal oxide is 0.5-30%, for example, 0.5%, 1%, 3%, 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25%, 27%, 29% or 30%, etc., preferably 0.5-15%.

[0031] Preferably, the specific surface area of ​​the first carrier is 200-400m 2 / g, for example 200m 2 / g, 220m 2 / g, 240m 2 / g, 260m 2 / g, 280m 2 / g、300m 2 / g、320m 2 / g、340m 2 / g、360m 2 / g、380m 2 / g or 400m 2 / g, etc.

[0032] Preferably, in the sulfur-resistant catalyst, the loading amount of the second active layer is 20-300 g / L, for example, 20 g / L, 40 g / L, 60 g / L, 80 g / L, 100 g / L, 120 g / L, 140 g / L, 160 g / L, 180 g / L, 200 g / L, 220 g / L, 240 g / L, 260 g / L, 280 g / L or 300 g / L, etc., preferably 100-300 g / L.

[0033] Preferably, in the sulfur-tolerant catalyst, the concentration of the second active component in the second active layer is 10-1000 g / ft 3 , for example 10g / ft 3 、30g / ft 3 , 50g / ft 3 , 100g / ft 3 , 200g / ft 3 、300g / ft 3 , 400g / ft 3 , 500g / ft 3 、600g / ft 3 , 700g / ft 3 , 800g / ft 3 , 900g / ft 3 or 1000g / ft 3 etc., preferably 50-500g / ft 3 .

[0034] Preferably, the second support comprises any one of aluminum oxide, ceria, cerium-zirconium oxide or cerium-zirconium-aluminum oxide, or a combination of at least two thereof.

[0035] Preferably, the second active component comprises a noble metal and a non-noble metal.

[0036] Preferably, the noble metal includes Pt and / or Pd.

[0037] Preferably, the non-precious metal includes any one of Fe, Mn, Mo, Mn, Fe, Ni, V, Ce, Nd, Ti, Cr, Nb, Hf, W, Cu or Co, or a combination of at least two thereof.

[0038] Preferably, when the second active component includes noble metals and non-noble metals, in the sulfur-tolerant catalyst, the concentration of the noble metal in the second active layer is 50-250 g / ft 3 , for example 50g / ft 3 , 75g / ft 3 , 125g / ft 3 、150g / ft 3 , 175g / ft 3 , 200g / ft 3 , 225g / ft 3 or 250g / ft 3 etc., the concentration of the non-precious metal is 80-800g / ft 3 , for example 80g / ft 3 , 100g / ft 3 , 200g / ft 3 、300g / ft3 , 400g / ft 3 , 500g / ft 3 、600g / ft 3 , 700g / ft 3 or 800g / ft 3 wait.

[0039] Preferably, the substrate comprises any one of cordierite, silicon carbide or a metal substrate.

[0040] Preferably, the structure of the substrate is a honeycomb structure.

[0041] Preferably, the cross-sectional shape of the substrate includes any one of a circle and a square.

[0042] In a second aspect, the present invention provides a method for preparing the sulfur-resistant catalyst according to the first aspect, the preparation method comprising the following steps:

[0043] coating the first slurry and the second slurry on a substrate, and forming a first active layer and a second active layer on the substrate through drying, calcining and hydrothermal aging to obtain the sulfur-resistant catalyst;

[0044] The first slurry includes a first active component and a first carrier, wherein the first active component includes any one or a combination of at least two of MoS2, MnS or CoS;

[0045] The second slurry includes a second active component and a second carrier, and the second active component includes a noble metal and / or a non-noble metal.

[0046] The preparation method provided by the present invention comprises coating a slurry containing active components onto a substrate, and combining drying, roasting and hydrothermal aging to form a sulfur-resistant catalyst having a specific arrangement of active components on the substrate, wherein the MoS2, MnS or CoS in the first active layer of the sulfur-resistant catalyst can effectively inhibit the poisoning of the second active component by sulfide impurities in methanol engine fuel (gray methanol), thereby reducing the risk of sulfur poisoning of the catalyst, and the MoS2, MnS or CoS active components can convert NO2 into NO, thereby reducing the proportion of NO2 in the exhaust gas and avoiding the harm of NO2 emissions to the environment and human health; the precious metal and / or non-precious metal active components in the second active layer can effectively reduce the concentrations of NO2, CO, hydrocarbons (HC), methanol and formaldehyde in the exhaust pollutants, thereby achieving purification of the pollutants.

[0047] Preferably, the first slurry further includes a first solvent, a first binder and a first thickener.

[0048] Preferably, the first solvent comprises water.

[0049] Preferably, the first solvent further comprises any one of alcohol or acid.

[0050] In the present invention, the first solvent may include water, or a combination of water and alcohol, or a combination of water and acid.

[0051] Preferably, the first binder includes any one of silica sol, pseudo-boehmite, aluminum sol or titanium sol, or a combination of at least two of them.

[0052] Preferably, the first thickener comprises hydroxyethyl cellulose and / or hydroxypropyl methyl cellulose.

[0053] Preferably, in the first slurry, the mass of the first solvent accounts for 60-80wt% of the total mass of the first slurry, such as 60wt%, 65wt%, 70wt%, 75wt% or 80wt%.

[0054] Preferably, in the first slurry, the mass of the first binder accounts for 5-20wt% of the total mass of the first slurry, for example, 5wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%, etc.

[0055] Preferably, in the first slurry, the mass of the first thickener accounts for 0.2-1wt% of the total mass of the first slurry, for example, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt% or 1.0wt%, etc.

[0056] It should be noted that, in the present invention, the coating amount of the first slurry and the amount of the first active component added to the first slurry are determined according to the loading amount of the first active layer and the concentration of the first active component of the first active layer in the sulfur-tolerant catalyst.

[0057] Preferably, the second slurry further includes a second solvent, a second binder and a second thickener.

[0058] Preferably, the second solvent comprises water.

[0059] Preferably, the second binder includes any one of pseudo-boehmite and aluminum sol.

[0060] Preferably, the second thickener includes any one of methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose or sodium carboxymethyl cellulose.

[0061] Preferably, in the second slurry, the mass of the second solvent accounts for 50-80wt% of the total mass of the second slurry, such as 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt% or 80wt%.

[0062] Preferably, in the second slurry, the mass of the second binder accounts for 5-20wt% of the total mass of the second slurry, for example, 5wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%, etc.

[0063] Preferably, in the second slurry, the mass of the second thickener accounts for 0.2-1wt% of the total mass of the second slurry, for example, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt% or 1.0wt%, etc.

[0064] It should be noted that, in the present invention, the coating amount of the second slurry and the amount of the second active component added to the second slurry are determined according to the loading amount of the second active layer and the concentration of the second active component of the second active layer in the sulfur-tolerant catalyst.

[0065] Preferably, the coating method of the first slurry and the second slurry on the substrate includes any one of coating method 1 and coating method 2.

[0066] Preferably, the first coating method includes: coating the second slurry and the first slurry on the surface of the substrate in sequence.

[0067] Preferably, the second coating method includes: coating the first slurry on the air inlet end of the first surface of the substrate, and coating the second slurry on the air outlet end of the first surface of the substrate.

[0068] Preferably, the calcination temperature is 300-400°C, for example, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C or 400°C.

[0069] Preferably, the calcination time is 3-5 h, for example, 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4.0 h, 4.2 h, 4.4 h, 4.6 h, 4.8 h or 5.0 h.

[0070] Preferably, the calcination atmosphere includes air atmosphere, nitrogen atmosphere or inert atmosphere.

[0071] Illustratively, the inert atmosphere includes any one of an argon atmosphere, a neon atmosphere, or a helium atmosphere.

[0072] Preferably, the temperature of the hydrothermal aging is 500-600°C, for example, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C or 600°C.

[0073] Preferably, the hydrothermal aging time is 12-24 h, for example, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h or 24 h.

[0074] In a third aspect, the present invention provides an application of the sulfur-resistant catalyst according to the first aspect, wherein the sulfur-resistant catalyst is applied to exhaust gas treatment of a methanol engine.

[0075] Compared with the prior art, the present invention has at least the following beneficial effects:

[0076] The sulfur-resistant catalyst for methanol engine post-treatment provided by the present invention is provided with two active layers on a substrate. The first active layer adopts MoS2, MnS or CoS as the first active component, effectively inhibiting the poisoning of the second active component by sulfide impurities in the methanol engine fuel (gray methanol), reducing the risk of catalyst sulfur poisoning, and the first active component can convert NO2 into NO, reducing the proportion of NO2 in the exhaust gas, and avoiding the harm of NO2 emissions to the environment and human health; the second active layer adopts precious metals and / or non-precious metals as the second active component, effectively reducing the concentration of NO2, CO, hydrocarbons (HC), methanol, and formaldehyde in the exhaust pollutants, thereby achieving purification of pollutants. The present invention has excellent sulfur resistance and can reduce NO2 emissions and purify pollutants such as CO, HC, methanol, and formaldehyde through the mutual synergistic effect of the first active component in the first active layer and the second active component in the second active layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 Schematic diagram of the structure of the sulfur-resistant catalyst provided in Example 1 and Example 2 of the present invention.

[0078] Figure 2 This is a schematic structural diagram of the sulfur-resistant catalyst provided in Example 3 of the present invention.

[0079] Figure 3 Schematic diagram of the structure of the catalyst provided in Example 11 of the present invention.

[0080] Among them, 1, substrate; 2, first active layer; 3, second active layer. DETAILED DESCRIPTION

[0081] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0082] Example 1

[0083] This embodiment provides a sulfur-resistant catalyst for methanol engine post-treatment, and its structural diagram is shown in FIG. Figure 1 As shown, the sulfur-resistant catalyst includes a substrate 1 and a first active layer 2 and a second active layer 3 arranged on the substrate 1. The second active layer 3 and the first active layer 2 are stacked in sequence in a direction away from the substrate 1. The second active layer 3 is arranged on the surface of the substrate 1, and the first active layer 2 is arranged on the surface of the second active layer 3 away from the substrate 1. With the direction perpendicular to the surface of the substrate 1 as the vertical direction, the ratio of the thickness of the first active layer 2 and the second active layer 3 in the vertical direction is 1:2, and the ratio of the thickness of the first active layer 2 to the substrate 1 in the vertical direction is 1:1. With the direction parallel to the surface of the substrate 1 as the horizontal direction, the areas of the first active layer 2 and the second active layer 3 in the horizontal direction are equal.

[0084] The first active layer 2 includes a first carrier and a first active component loaded on the first carrier, the first active component is MoS2, and the first carrier has a specific surface area of ​​200m 2 / g of alumina, in the sulfur-tolerant catalyst, the concentration of MoS2 in the first active layer 2 is 500g / ft 3 The loading amount of the first active layer 2 in the sulfur-tolerant catalyst is 100 g / L.

[0085] The second active layer 3 includes a second carrier and a second active component supported on the second carrier. The second carrier is cerium oxide. The second active component is a noble metal and a non-noble metal. The noble metal is Pt and the non-noble metal is Fe. In the sulfur-tolerant catalyst, the concentration of Pt in the second active layer 3 is 50 g / ft 3 , the concentration of Fe is 100g / ft 3 The loading amount of the second active layer 3 in the sulfur-tolerant catalyst is 200 g / L.

[0086] The substrate 1 is made of cordierite honeycomb ceramics, and the cross-section of the substrate 1 is circular.

[0087] This embodiment also provides a method for preparing the above-mentioned sulfur-resistant catalyst, comprising the following steps:

[0088] (1) MoS2 and alumina in a formulated amount are mixed with water, aluminum sol and hydroxyethyl cellulose to obtain a first slurry, wherein the amount of water added accounts for 70wt% of the total mass of the first slurry, the mass of the aluminum sol accounts for 10wt% of the total mass of the first slurry, and the mass of the hydroxyethyl cellulose accounts for 0.2wt% of the total mass of the first slurry.

[0089] The formulated amounts of Pt, Fe and cerium oxide are mixed with water, pseudo-boehmite and hydroxyethyl cellulose to obtain a second slurry, wherein the amount of water added accounts for 70wt% of the total mass of the second slurry, the mass of the pseudo-boehmite accounts for 5wt% of the total mass of the second slurry, and the mass of the hydroxyethyl cellulose accounts for 0.5wt% of the total mass of the second slurry.

[0090] (2) The second slurry and the first slurry obtained in step (1) are sequentially coated on the surface of the cordierite honeycomb ceramic, wherein the coating amount of MoS2 and alumina in the first slurry is 100 g / L, and the coating amount of Pt, Fe and cerium oxide in the second slurry is 200 g / L, to obtain a semi-finished product.

[0091] (3) The semi-finished product obtained in step (2) is dried, and then the dried product is calcined at 350° C. for 4 h in an air atmosphere, followed by hydrothermal aging at 550° C. for 16 h to obtain a sulfur-resistant catalyst.

[0092] Example 2

[0093] This embodiment provides a sulfur-resistant catalyst for methanol engine post-treatment, and its structural diagram is shown in FIG. Figure 1 As shown, the sulfur-resistant catalyst includes a substrate 1 and a first active layer 2 and a second active layer 3 arranged on the substrate 1. The second active layer 3 and the first active layer 2 are stacked in sequence in a direction away from the substrate 1. The second active layer 3 is arranged on the surface of the substrate 1, and the first active layer 2 is arranged on the surface of the second active layer 3 away from the substrate 1. With the direction perpendicular to the surface of the substrate 1 as the vertical direction, the ratio of the thickness of the first active layer 2 and the second active layer 3 in the vertical direction is 1:4, and the ratio of the thickness of the first active layer 2 to the substrate 1 in the vertical direction is 1:0.5. With the direction parallel to the surface of the substrate 1 as the horizontal direction, the areas of the first active layer 2 and the second active layer 3 in the horizontal direction are equal.

[0094] The first active layer 2 includes a first carrier and a first active component loaded on the first carrier, the first active component is CoS, and the first carrier has a specific surface area of ​​400m 2 / g of titanium-doped alumina, in the first carrier, the mass percentage of titanium in alumina is 5%, and the concentration of CoS in the first active layer 2 of the sulfur-tolerant catalyst is 300g / ft 3The loading amount of the first active layer 2 in the sulfur-tolerant catalyst is 100 g / L.

[0095] The second active layer 3 includes a second carrier and a second active component supported on the second carrier. The second carrier is cerium zirconium aluminum oxide (the molar ratio of cerium, zirconium and aluminum is 5:3:2). The second active component is a noble metal and a non-noble metal. The noble metal is Pd and the non-noble metal is Mn. In the sulfur-tolerant catalyst, the concentration of Pd in ​​the second active layer 3 is 75 g / ft 3 , Mn concentration is 200g / ft 3 The loading amount of the second active layer 3 in the sulfur-tolerant catalyst is 300 g / L.

[0096] The substrate 1 is made of cordierite honeycomb ceramics, and the cross-section of the substrate 1 is circular.

[0097] This embodiment also provides a method for preparing the above-mentioned sulfur-resistant catalyst, comprising the following steps:

[0098] (1) CoS and titanium-doped alumina in a formulated amount are mixed with water, silica sol and hydroxyethyl cellulose to obtain a first slurry, wherein the amount of water added accounts for 80wt% of the total mass of the first slurry, the mass of the silica sol accounts for 10wt% of the total mass of the first slurry, and the mass of the hydroxyethyl cellulose accounts for 1wt% of the total mass of the first slurry.

[0099] The formulated amounts of Pd, Mn and cerium zirconium aluminum oxide are mixed with water, aluminum sol and sodium carboxymethyl cellulose to obtain a second slurry, wherein the amount of water added accounts for 80wt% of the total mass of the second slurry, the mass of the aluminum sol accounts for 10wt% of the total mass of the second slurry, and the mass of the sodium carboxymethyl cellulose accounts for 0.5wt% of the total mass of the second slurry.

[0100] (2) The second slurry and the first slurry obtained in step (1) are sequentially coated on the surface of the cordierite honeycomb ceramic, wherein the coating amount of CoS and titanium-doped alumina in the first slurry is 100 g / L, and the coating amount of Pd, Mn and cerium-zirconium-aluminum oxide in the second slurry is 300 g / L, to obtain a semi-finished product.

[0101] (3) Drying the semi-finished product obtained in step (2), and then calcining the dried product at 400° C. for 3 h in an argon atmosphere, followed by hydrothermal aging at 500° C. for 24 h to obtain a sulfur-resistant catalyst.

[0102] Example 3

[0103] This embodiment provides a sulfur-resistant catalyst for methanol engine post-treatment, and its structural diagram is shown in FIG. Figure 2As shown, the sulfur-resistant catalyst includes a substrate 1 and a first active layer 2 and a second active layer 3 arranged on the substrate 1. The first active layer 2 is arranged at the air inlet end of the first surface of the substrate 1, and the second active layer 3 is arranged at the air outlet end of the first surface of the substrate 1. The direction parallel to the first surface of the substrate 1 is the horizontal direction. The first active layer 2 and the second active layer 3 are arranged side by side and connected to each other in the horizontal direction. The area ratio of the first active layer 2 and the second active layer 3 is 1:2. The direction perpendicular to the surface of the substrate 1 is the vertical direction. The thickness of the first active layer 2 and the second active layer 3 in the vertical direction is equal, and the thickness ratio of the first active layer 2 to the substrate 1 in the vertical direction is 1:0.5.

[0104] The first active layer 2 includes a first carrier and a first active component loaded on the first carrier, the first active component is MnS, and the first carrier has a specific surface area of ​​300m 3 / g of titanium oxide, in the sulfur-tolerant catalyst, the concentration of MnS in the first active layer 2 is 400g / ft 3 The loading amount of the first active layer 2 in the sulfur-tolerant catalyst is 200 g / L.

[0105] The second active layer 3 includes a second carrier and a second active component supported on the second carrier. The second carrier is cerium oxide. The second active component is a noble metal and a non-noble metal. The noble metal is Pt and the non-noble metal is Co. In the sulfur-tolerant catalyst, the concentration of Pt in the second active layer 3 is 100 g / ft 3 , the concentration of Co is 100g / ft 3 The loading amount of the second active layer 3 in the sulfur-tolerant catalyst is 300 g / L.

[0106] The substrate 1 is made of cordierite honeycomb ceramics, and the cross-section of the substrate 1 is circular.

[0107] This embodiment also provides a method for preparing the above-mentioned sulfur-resistant catalyst, comprising the following steps:

[0108] (1) Mixing the formulated amounts of MnS and titanium oxide with water, titanium sol and hydroxyethyl cellulose to obtain a first slurry, wherein the amount of water added accounts for 60wt% of the total mass of the first slurry, the mass of the titanium sol accounts for 5wt% of the total mass of the first slurry, and the mass of the hydroxyethyl cellulose accounts for 0.5wt% of the total mass of the first slurry.

[0109] The formulated amounts of Pt, Co and cerium oxide are mixed with water, pseudo-boehmite and hydroxyethyl cellulose to obtain a second slurry, wherein the amount of water added accounts for 60wt% of the total mass of the second slurry, the mass of the pseudo-boehmite accounts for 5wt% of the total mass of the second slurry, and the mass of the hydroxyethyl cellulose accounts for 0.5wt% of the total mass of the second slurry.

[0110] (2) The first slurry and the second slurry obtained in step (1) are coated on the gas inlet end and the gas outlet end of the first surface of the cordierite honeycomb ceramic respectively, the coating amount of MoS and alumina in the first slurry is 200 g / L, the coating amount of Pt, Fe and cerium oxide in the second slurry is 300 g / L, to obtain a semi-finished product.

[0111] (3) The semi-finished product obtained in step (2) is dried, and then the dried product is calcined at 300℃ for 5h, the atmosphere of calcination is argon atmosphere, and then hydrothermal aging is carried out at 600℃ for 12h, to obtain a sulfur-tolerant catalyst.

[0112] Example 4

[0113] The difference between this embodiment and example 1 is only that the second active component omits the non-noble metal, and only uses the noble metal as the second active component. The rest is the same as example 1.

[0114] Example 5

[0115] The difference between this embodiment and example 1 is only that the loading amount of the first active layer in the sulfur-tolerant catalyst is 80 g / L. The rest is the same as example 1.

[0116] Example 6

[0117] The difference between this embodiment and example 1 is only that the loading amount of the first active layer in the sulfur-tolerant catalyst is 500 g / L. The rest is the same as example 1.

[0118] Example 7

[0119] The difference between this embodiment and example 1 is only that the loading amount of the second active layer in the sulfur-tolerant catalyst is 80 g / L. The rest is the same as example 1.

[0120] Example 8

[0121] The difference between this embodiment and example 1 is only that the loading amount of the second active layer in the sulfur-tolerant catalyst is 320 g / L. The rest is the same as example 1.

[0122] Example 9

[0123] The difference between this embodiment and example 3 is only that the area ratio of the first active layer and the second active layer is 1:6. The rest is the same as example 3.

[0124] Example 10

[0125] The difference between this embodiment and example 3 is only that the area ratio of the first active layer and the second active layer is 2:1. The rest is the same as example 3.

[0126] Example 11

[0127] The only difference between this embodiment and embodiment 3 is that the structural diagram of the catalyst provided in this embodiment is as follows: Figure 3 In the above, the first active layer 2 is provided at the gas outlet end of the first surface of the substrate 1, and the second active layer 3 is provided at the gas inlet end of the first surface of the substrate 1. The rest of the contents are the same as those in Example 3.

[0128] Comparative Example 1

[0129] The only difference between this comparative example and Example 1 is that the second active layer is omitted and only the first active layer is provided on the surface of the substrate. The rest of the contents are the same as those of Example 1.

[0130] Comparative Example 2

[0131] The only difference between this comparative example and Example 1 is that the first active layer is omitted and only the second active layer is provided on the surface of the substrate. The rest of the contents are the same as Example 1.

[0132] Comparative Example 3

[0133] The only difference between this comparative example and Example 1 is that the first active component MoS2 in the first active layer is replaced by MoO x (x is 2). The rest of the contents are the same as those in Example 1.

[0134] Comparative Example 4

[0135] The only difference between this comparative example and Example 1 is that the first active component MoS2 in the first active layer is replaced by MoO x (x is 3). The rest of the contents are the same as those in Example 1.

[0136] Performance Testing

[0137] The catalysts provided in the above examples and comparative examples (denoted as Catn, such as Cat1 for the catalyst provided in Example 1) were directly tested for catalytic performance, and the catalysts provided in the above examples and comparative examples after sulfurization were tested for catalytic performance. The catalyst sulfurization conditions were: 5% H2O, 500ppm SO2, and the rest air, with a space velocity of 20000h -1 The temperature was programmed to rise from room temperature to 300 °C and maintained for 2 h, which was repeated three times. The sulfided catalysts were named Cat1S, Cat2S, and Cat3S, respectively.

[0138] The catalyst testing conditions include:

[0139] Methanol engine exhaust (including 10% O2, 6% CO2, 10% H2O, 1000ppm CO, 500ppm NO2, 400ppm C3H6, 2000ppm CH3OH, and the rest N2), space velocity 20000h -1 , starting from room temperature, the temperature was raised to 500℃ at a rate of 10℃ / min, and the T50 and T90 of CO (i.e., the reaction temperature corresponding to 50% or 90% conversion), the T50 and T90 of C3H6, the T50 and T90 of CH3OH, and the highest conversion of NO2 were recorded. The test results are shown in Table 1

[0140] Table 1

[0141]

[0142]

[0143] The test results show that:

[0144] (1) It can be seen from Examples 1 to 3 that the present invention achieves the sulfur resistance of the catalyst, reduces the sulfur poisoning risk of the catalyst, reduces NO2 emissions, and improves the purification of pollutants such as CO, hydrocarbons, methanol, and formaldehyde through the synergistic effect of the MoS2, MnS or CoS active components in the first active layer and the precious metal and / or non-precious metal active components in the second active layer.

[0145] (2) By comparing Example 1 and Example 4, it can be seen that if the addition of non-precious metals to the second active component of the present invention is omitted and only precious metals are used as active components, the purification effect of exhaust pollutants will be reduced and the catalytic performance of the sulfur-resistant catalyst will deteriorate.

[0146] (3) By comparing Example 1 with Examples 5-6, it can be seen that if the loading amount of the first active layer in the sulfur-tolerant catalyst of the present invention is too low, the adsorption of SO2 by the sulfur-tolerant catalyst will be deteriorated, and the poisoning of the second active component by sulfide impurities cannot be effectively suppressed, thereby increasing the risk of catalyst poisoning. At the same time, the conversion of NO2 to NO cannot be achieved, and the proportion of NO2 in the exhaust gas increases. If the loading amount of the first active layer in the sulfur-tolerant catalyst is too high, the gas diffusion will be slowed down, thereby reducing the efficiency of the catalyst.

[0147] (4) By comparing Example 1 with Examples 7-8, it can be seen that if the loading amount of the second active layer in the sulfur-tolerant catalyst is too low, the purification effect of the catalyst on pollutants such as CO, HC, methanol, and formaldehyde will be poor; if the loading amount of the second active layer in the sulfur-tolerant catalyst is too high, the gas diffusion will be slowed down, reducing the catalyst efficiency.

[0148] (5) By comparing Example 1 with Examples 9-10, it can be seen that in the sulfur-resistant catalyst provided by the present invention in which the first active layer and the second active layer are arranged side by side on the substrate, if the ratio of the areas of the first active layer and the second active layer is too low, and the area proportion of the first active layer is too small, the sulfur resistance of the catalyst will be reduced, and the NO2 conversion rate will be reduced; if the areas of the first active layer and the second active layer are too high, and the area of ​​the first active layer is higher than the area of ​​the second active layer, the gas diffusion will be slowed down, and the catalyst efficiency will be reduced.

[0149] (6) By comparing Example 1 and Example 11, it can be seen that if the first active layer is arranged at the gas outlet end of the substrate and the second active layer is arranged at the gas inlet end of the substrate, the second active layer first contacts the gas to be post-treated, resulting in sulfur poisoning of the second active layer, which affects the overall catalytic performance and sulfur resistance of the catalyst.

[0150] (7) By comparing Example 1 with Comparative Examples 1-2, it can be seen that if the first active layer of the acid-resistant catalyst of the present invention is omitted, the sulfur resistance of the catalyst will decrease, and the purification performance of the catalyst for pollutants and the conversion performance of NO2 after sulfurization will both deteriorate; if the second active layer is omitted, the purification effect of the catalyst for pollutants will be greatly reduced.

[0151] (8) By comparing Example 1 with Comparative Examples 3-4, it can be seen that if the first active component of the present invention is replaced by molybdenum oxide, the sulfur resistance of the catalyst will decrease, and the catalytic effect of the catalyst after sulfurization will be significantly worse.

[0152] In summary, the sulfur-resistant catalyst for methanol engine post-treatment provided by the present invention has two active layers arranged on a substrate, and the first active layer adopts MoS2, MnS or CoS as the first active component, which effectively inhibits the poisoning of the second active component by sulfide impurities in the methanol engine fuel (gray methanol), reduces the risk of catalyst sulfur poisoning, and the first active component can convert NO2 into NO, reduce the proportion of NO2 in the exhaust gas, and avoid the harm of NO2 emissions to the environment and human health; the second active layer adopts precious metals or non-precious metals as the second active component, effectively reducing the concentration of NO2, CO, hydrocarbons (HC), methanol, and formaldehyde in the exhaust pollutants, thereby achieving purification of pollutants. The present invention has excellent sulfur resistance and can reduce NO2 emissions and purify pollutants such as CO, HC, methanol, and formaldehyde through the mutual synergistic effect of the first active component in the first active layer and the second active component in the second active layer.

[0153] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A sulfur-resistant catalyst for methanol engine post-treatment, characterized in that: The sulfur-resistant catalyst includes a substrate and a first active layer and a second active layer disposed on the substrate, wherein the first active layer includes a first carrier and a first active component supported on the first carrier, and the second active layer includes a second carrier and a second active component supported on the second carrier; The first active component includes any one of MoS2, MnS or CoS or a combination of at least two thereof; the second active component includes a noble metal and / or a non-noble metal.

2. The sulfur-resistant catalyst according to claim 1, characterized in that The arrangement of the first active layer and the second active layer on the substrate includes any one of the first and second arrangements; the first arrangement includes: the first active layer and the second active layer are stacked on the substrate; the second arrangement includes: the first active layer and the second active layer are arranged in parallel on the substrate; Preferably, the first mode specifically includes: the second active layer is provided on the surface of the substrate, and the first active layer is provided on the surface of the second active layer away from the substrate; Preferably, the second mode specifically includes: the first active layer is arranged at the air inlet end of the first surface of the substrate, and the second active layer is arranged at the air outlet end of the first surface of the substrate.

3. The sulfur-resistant catalyst according to claim 2, characterized in that In the first embodiment, a direction perpendicular to the surface of the substrate is defined as a vertical direction, and a ratio of the thickness of the first active layer to that of the second active layer in the vertical direction is 1:(1-5); Preferably, in the first embodiment, the direction parallel to the surface of the substrate is defined as a horizontal direction, and the areas of the first active layer and the second active layer in the horizontal direction are equal; Preferably, in the first embodiment, a direction perpendicular to the surface of the substrate is defined as a vertical direction, and a thickness ratio of the first active layer to the substrate in the vertical direction is 1:(0.5-1.5).

4. The sulfur-resistant catalyst according to claim 2, characterized in that In the second embodiment, a direction parallel to the first surface of the substrate is defined as a horizontal direction, and the first active layer and the second active layer are connected to each other in the horizontal direction; Preferably, in the second embodiment, with the direction parallel to the first surface of the substrate as the horizontal direction, the area ratio of the first active layer to the second active layer in the horizontal direction is 1:(1-5); Preferably, in the second embodiment, a direction perpendicular to the first surface of the substrate is defined as a vertical direction, and the thicknesses of the first active layer and the second active layer in the vertical direction are equal; Preferably, in the second mode, taking a direction perpendicular to the first surface of the substrate as a vertical direction, a thickness ratio of the first active layer to the substrate in the vertical direction is 1:(0.5-1.5).

5. The sulfur-resistant catalyst according to any one of claims 1 to 4, characterized in that: In the sulfur-tolerant catalyst, the loading amount of the first active layer is 20-500 g / L, preferably 100-400 g / L; Preferably, in the sulfur-tolerant catalyst, the concentration of the first active component of the first active layer is 100-2000 g / ft 3 , preferably 300-1000g / ft 3 ; Preferably, in the sulfur-tolerant catalyst, the first support comprises a metal oxide or a metal oxide doped with a doping element; Preferably, the metal oxide includes any one or a combination of at least two of molybdenum oxide, titanium oxide, cerium oxide, tungsten oxide, magnesium oxide, aluminum oxide, zirconium oxide, cobalt oxide, nickel oxide, niobium oxide, indium oxide, tin oxide, zinc oxide or copper oxide; Preferably, the doping element includes any one or a combination of at least two of strontium, titanium, zirconium, niobium, iron, zinc, silver, samarium, europium, lithium, sodium, potassium, cesium, calcium, barium, magnesium, vanadium, chromium, neodymium, praseodymium, yttrium or lanthanum; Preferably, the specific surface area of ​​the first carrier is 200-400m 2 / g.

6. The sulfur-resistant catalyst according to any one of claims 1 to 5, characterized in that: In the sulfur-tolerant catalyst, the loading amount of the second active layer is 20-300 g / L, preferably 100-300 g / L; Preferably, in the sulfur-tolerant catalyst, the concentration of the second active component in the second active layer is 10-1000 g / ft 3 , preferably 50-500g / ft 3 ; Preferably, the second support comprises any one or a combination of at least two of aluminum oxide, ceria, cerium-zirconium oxide, or cerium-zirconium-aluminum oxide; Preferably, the second active component comprises a noble metal and a non-noble metal; Preferably, the noble metal comprises Pt and / or Pd; Preferably, the non-precious metal includes any one or a combination of at least two of Fe, Mn, Mo, Mn, Fe, Ni, V, Ce, Nd, Ti, Cr, Nb, Hf, W, Cu or Co; Preferably, when the second active component includes noble metals and non-noble metals, in the sulfur-tolerant catalyst, the concentration of the noble metal in the second active layer is 50-250 g / ft 3 , the concentration of the non-precious metal is 80-800g / ft 3 .

7. The sulfur-resistant catalyst according to any one of claims 1 to 6, characterized in that: The substrate comprises any one of cordierite, silicon carbide or a metal substrate; Preferably, the structure of the substrate is a honeycomb structure; Preferably, the cross-sectional shape of the substrate includes any one of a circle and a square.

8. A method for preparing a sulfur-resistant catalyst according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: coating the first slurry and the second slurry on a substrate, and forming a first active layer and a second active layer on the substrate through drying, calcining and hydrothermal aging to obtain the sulfur-resistant catalyst; The first slurry includes a first active component and a first carrier, wherein the first active component includes any one or a combination of at least two of MoS2, MnS or CoS; The second slurry includes a second active component and a second carrier, and the second active component includes a noble metal and / or a non-noble metal.

9. The preparation method according to claim 8, characterized in that The first slurry further includes a first solvent, a first binder and a first thickener; Preferably, in the first slurry, the mass of the first solvent accounts for 60-80 wt% of the total mass of the first slurry; Preferably, in the first slurry, the mass of the first binder accounts for 5-20wt% of the total mass of the first slurry; Preferably, in the first slurry, the mass of the first thickener accounts for 0.2-1 wt% of the total mass of the first slurry; Preferably, the second slurry further includes a second solvent, a second binder and a second thickener; Preferably, in the second slurry, the mass of the second solvent accounts for 50-80 wt% of the total mass of the second slurry; Preferably, in the second slurry, the mass of the second binder accounts for 5-20wt% of the total mass of the second slurry; Preferably, in the second slurry, the mass of the second thickener accounts for 0.2-1 wt% of the total mass of the second slurry; Preferably, the calcination temperature is 300-400°C; Preferably, the temperature of the hydrothermal aging is 500-600°C.

10. Use of the sulfur-resistant catalyst according to any one of claims 1 to 9, characterized in that: The sulfur-resistant catalyst is used for treating tail gas of a methanol engine.

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