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  • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/18—Arsenic, antimony or bismuth
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  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
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  • B01J21/12—Silica and alumina
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  • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
  • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/56—Platinum group metals
  • B01J23/64—Platinum group metals with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/644—Arsenic, antimony or bismuth
  • B01J23/6447—Bismuth
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  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/61—Surface area
  • B01J35/613—10-100 m2/g
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  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/61—Surface area
  • B01J35/615—100-500 m2/g
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  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
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  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
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  • B01J35/635—0.5-1.0 ml/g
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  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/63—Pore volume
  • B01J35/638—Pore volume more than 1.0 ml/g
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  • B01J35/70—Catalysts, in general, characterised by their form or physical properties characterised by their crystalline properties, e.g. semi-crystalline
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  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
  • B01J37/0027—Powdering
  • B01J37/0045—Drying a slurry, e.g. spray drying
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  • B01J37/0201—Impregnation
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  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0201—Impregnation
  • B01J37/0203—Impregnation the impregnation liquid containing organic compounds
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  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/08—Heat treatment
  • B01J37/082—Decomposition and pyrolysis
  • B01J37/088—Decomposition of a metal salt
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  • B01J6/00—Heat treatments such as Calcining; Fusing ; Pyrolysis
  • B01J6/001—Calcining
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  • B01D2255/2092—Aluminium
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D2255/00—Catalysts
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  • B01D2255/2096—Bismuth
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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  • B01D2255/30—Silica
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01D—SEPARATION
  • B01D2258/00—Sources of waste gases
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  • B01D2258/012—Diesel engines and lean burn gasoline engines
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01J2235/00—Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
  • B01J2235/15—X-ray diffraction
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

• the invention relates to a method to prepare an alumina bismuth catalyst support for emission control applications, to an alumina bismuth catalyst support prepared according to the method of the invention and to an alumina bismuth catalyst support having specific characteristics.
• the main raw emission pollutants in exhaust gases are CO, NOx, unburned hydrocarbons and soot particles.
• Catalyst systems including various components and precious metals, for application in emission control are known in the art.
• Diesel Oxida tion Catalyst (DOC) containing precious metals supported on high-surface area refractory oxides such as alumina or silica-alumina converts CO into CO 2 and the unburned hydro carbons into CO 2 and water.
• DOC Diesel Oxida tion Catalyst
• WO 2017/064498 A1 and US 7,611 ,680 B2 disclose the beneficial effect of low temperature conversion for CO and hydrocarbons by the addition of B12O3 to a catalyst.
• US 7,611 ,680 it is described that the bismuth is added as a promoter by an in situ reduction process.
• WO 2017/064498 A1 the bismuth is supported on a support.
• the prior art therefore teaches the incorporation of the B12O3 as a separate crystalline phase. This leads to low specific surface area of the promoting additive and therefore to limited beneficial interaction with the active precious metal.
• the object of the present invention is therefore to provide an improved alumina bismuth support applicable in emission control catalysis having improved characteristics and a novel method for preparation of same.
• a method to prepare an alu mina bismuth catalyst support comprising the steps of: i) providing an aluminum containing composition, wherein the aluminum containing composition comprises a) boehmite or b) silica containing aluminum oxide; ii) providing a bismuth aqueous solution, the bismuth aqueous solution comprising a bismuth salt and a base comprising nitrogen, preferably ammonia, and having a pH value of between 4 and 9; iii) contacting the aluminum containing composition with the bismuth aqueous solution to form an aluminum bismuth intermediate; wherein the contacting is carried out:
• step i) involving the aluminum containing composition com prising boehmite by mixing the aluminum containing composition in dried powder form or in the form of a suspension with the bismuth aqueous solution to form an aluminum bismuth intermediate, or
• step i) involving the aluminum containing composition com prising silica containing aluminum oxide by impregnating the aluminum contain ing composition in dried powder form with the bismuth aqueous solution to form an aluminum bismuth intermediate, and iv) calcining the aluminum bismuth intermediate to form an alumina bismuth catalyst support.
• the aluminum bismuth intermediate may also be called a boehmite bismuth intermediate in case in step i) the aluminum containing composition comprised boehmite.
• the aluminum bismuth intermediate may also be called a silica aluminum oxide bismuth intermediate in case in step i) the aluminum containing composition comprised silica.
• the aluminum containing composition consists of boehmite or consists of sil ica containing aluminum oxide with respect to the aluminum containing compounds in the composition.
• the aluminum containing composition may for example (beside silica or other components) additionally comprise one or more dopants.
• the aluminum oxide in the silica containing aluminum oxide preferably is or comprises transitional alumina.
• the silica containing aluminum oxide more preferably comprises transitional alumina, silica and one or more dopant.
• the transitional alumina is one or more of gamma (g), delta (d) or theta ( Q ) aluminum oxide, and preferably is or com prises gamma alumina.
• the aluminum containing composition preferably com prises at least 50 wt.-% silica containing aluminum oxide.
• the aluminum containing composition preferably comprises at least 50 wt.% boehmite.
• the aluminum containing composition contains boehmite (AIOOH) with or without one or more dopants and even more prefer ably the aluminum containing composition contains boehmite, silica and one or more dopants.
• the S1O2 content is be tween 1 and 40 wt.-%, preferably between 1 and 20 wt.-%, based on the total dry mass of S1O2, aluminum oxide, aluminum oxide hydroxide and aluminum trihydroxide.
• the aluminum containing composition does not additionally comprise aluminum tri hydroxide, but only aluminum oxide or aluminum oxide hydroxide.
• Boehmite includes boehmite as such and pseudo-boehmite.
• the boehmite may be de fined as any alumina having the molecular formula AIOOH * XH2O, where x is between 0 and 0.5.
• Aluminum oxide hydroxide is the same as boehmite.
• Alumina is understood to mean aluminum oxide and/or aluminum oxide hydroxide.
• Aluminum oxide is AI2O3.
• the dopants may be oxides of or water-soluble salts of alkaline earth metals, transition metals, for example Zr, Ti, rare-earth elements or mixtures thereof.
• their con tent is between 0 and 10 wt.-%, more preferably between 0 and 5 wt.-%, calculated as oxides based on the total mass of the aluminum oxide, aluminum oxide hydroxide and aluminum trihydroxide.
• the transitional metals are preferably Mn, Fe, Cu, Nb, Zr, Ti or mixtures thereof and more preferably Zr, Ti or mixtures thereof.
• the dopants may also be alkaline earth metal carbonates, in particular barium carbonate.
• the aluminum containing composition may be provided in dried powder form or in the form of an aluminum suspension. If the aluminum containing composition is in the form of an aluminum suspension, the suspension comprises the aluminum containing com position and at least water, preferably in a weight ratio of 2:98 to 20:80.
• the aluminum suspension may further include pH modifying additives for example carboxylic acid or ammonia, preferably mono-carboxylic acids such as acetic acid.
• the aluminum suspension is preferably a boehmite suspension wherein the boehmite is prepared by hydrolysis of an Al-alkoxide, most preferably involving hydrothermal aging. Hydrothermal ageing is carried out between 100 und 300°C, preferably between 120 and 240°C for 0,5 hours to 30 hours, preferably between 3 hours and 10 hours; time and temperature are independently selected.
• the bismuth aqueous solution preferably comprises a water-soluble Bi 3+ salt, more pref erably a Bi nitrate or a Bi citrate and most preferably a Bi Citrate.
• the anion of such salts are preferably organic compounds such as an organic acid.
• the pH value of the bismuth aqueous solution is between 4 and 9, preferably between 6 and 8.
• Contacting means either a) mixing the aluminum containing composition, preferably the aluminum suspension, with the bismuth aqueous solution to form the aluminum bismuth intermediate or b) impregnating the aluminum containing composition in dried powder form with the bismuth aqueous solution to form the aluminum bismuth intermediate.
• the aluminum containing composition is or comprises a silica containing alumi num oxide step iii) is with “impregnation” and in case the aluminum containing composi tion is or comprises boehmite step iii) is with “mixing”.
• Impregnation of the aluminum containing composition may be carried out by any im pregnation method known in the art, preferably by incipient wetness impregnation. Such a method provides for impregnating between 80 and 100% of the aluminum containing composition with the bismuth aqueous solution. By % is meant the ratio of (volume of liquid added)/(pore volume).
• the method may include the further step of drying, preferably spray drying, the aluminum bismuth intermediate to form a dried aluminum bismuth intermediate that will then be calcined.
• the aluminum bismuth intermediate or the dried aluminum bismuth intermediate is cal cined at a temperature of between 500 and 1000°C, more preferably between 600 and 900°C, even more preferably at a temperature of between 500 and 700°C, and inde pendent thereof for a period of at least 0.5 hours, preferably between 0.5 and 5 hours, preferably 3 hours.
• an alumina bismuth cat alyst support prepared according to the method of the invention.
• an alumina bismuth catalyst support comprising: i) at least 80 wt.-% of a transition alumina based material; and ii) between 1 and 20 wt.-% of a bismuth oxide, characterized by a crystallinity value CB I below 10, preferably a crystallinity value CBI of less than 3.
• the transition alumina based material preferably is or may comprise aluminum oxide, silica and/or dopants. More preferably the transition alumina based material comprises aluminum oxide, silica and one or more dopants.
• the transition alumina based material preferably comprises Gamma, Delta or Theta alu minum oxides, or mixtures thereof.
• the transition alumina based material preferably comprises at least 50 wt.-% of alumi num oxides
• the S1O2 content is be tween 1 and 40 wt.-%, preferably between 1 and 20 wt.-%, based on the oxide mass of silica and the aluminum oxider
• the dopants may be oxides of or alkaline earth metals of transition metals, for example Zr, Ti, rare-earth metals or mixtures thereof. Preferably their content is between 0 and 10 wt.-%, preferably between 0 and 5 wt.-%, calculated as oxides based on the total mass of the aluminum oxide, silica and the dopant.
• the transitional metals are prefera bly Mn, Fe, Cu, Nb, Zr, Ti or mixtures thereof and more preferably Zr, Ti or mixtures thereof.
• the alumina bismuth catalyst support comprises a BET specific surface area between 50 and 300 m 2 /g, preferably between 100 and 200 m 2 /g.
• the alumina bismuth catalyst support comprises a pore volume of between 0.1 and 1.5 ml/g, preferably between 0,5 and 1 ,0 ml/g.
• an improved heterogeneous catalysts is obtained with improved contact between the active phase (noble metals) and the promotor. This is achieved by a homogeneous dispersion of the promotor bismuth oxide in the support material matrix leading to good accessibility of the promotor by the noble metals and uniform promotor-noble metal arrangements throughout the entire catalyst.
• the virtually X-ray amorphous state of the bismuth oxide is indicative for such a homogeneous dispersion in the matrix of the alumina based material.
• the bismuth oxide is homogenously dispersed in the matrix of the alumina based material. Without being bound by theory the Applicant believes that a homogenous dispersion of the bismuth oxide small crystals in a virtually X-ray amorphous state leads to the ben eficial properties of the composite.
• the X-ray amorphous state may be described by the crystallinity value as given below.
• the crystallinity value as used herein is determined in accordance with the following method.
• the normalized intensity ratio of these two reflections (see equation 1 ) is a measure for the crystallinity of bismuth oxide CBI on the transition alumina based material
• I24 Intensity of baseline near the reflex around 24° hr. Intensity of the reflex around 67°
• I72 Intensity of baseline near the reflex around 72° rri Bi : mass of B1 2 O 3 / (mass of B1 2 O 3 + mass of transition alumina based material
• Homogeneity is measured by scanning-electron-microscope (SEM) cross-section imaging, optionally together with EDX (Energy Dispersive X-ray Analysis) element mapping revealing the domain sizes of the transition alumina based material, the bismuth oxide and the alumina bismuth catalyst support.
• SEM scanning-electron-microscope
• EDX Electronic Dispersive X-ray Analysis
• Surface area and pore volume are measured with N2 physisorption using typical volumet ric devices like the Quadrasorb from Quantachrome at the temperature of liquid nitrogen. The surface area is determined using BET theory (DIN ISO 9277) while the pore volume is determined according to DIN 66131 .
• the pore radius range is between 18 and 1000A.
• alumina bis muth catalyst support as hereinbefore described as a support for an oxidation catalyst, preferably comprising platinum (Pt) and/or palladium (Pd), in particular a diesel oxida tion catalyst for vehicle emission control applications.
• Figure 1 is a powder XRD of the composition obtained in Example 1 and Example 2 compared to Comparative Examples 1-3 showing the difference in crystallinity of B12O3;
• Figure 2 is a powder XRD of the composition obtained in Example 3 compared to Com parative Example 4, together with a simulated XRD pattern of B12O3 showing the differ ence in crystallinity of B12O3.
• Example 1 (aluminum containing composition comprising boehmite and silica)
• a bismuth oxide doped silica-alumina with 3 wt.-% B12O3 was prepared according to the present invention.
• a Bi-Citrate solution was prepared by adding 516 g Bi-Citrate to 1 7kg H2O. 190 g of a 25 wt.-% NH3 solution was added to obtain a clear solution with pH 7. The Bi-Citrate solution was added to an alumina suspension containing boehmite and silica in a 95:5 weight ratio calculated as per the oxides (SIRAL 5). The mixture was spray dried and calcined at 950°C for 3h.
• Example 2 (aluminum containing composition comprising silica containing aluminum ox ide)
• a bismuth oxide doped silica-alumina with 3 wt.-% B1 2 O 3 was prepared according to the present invention.
• a Bi-Citrate solution was prepared by adding 12,2 g Bi-Citrate to 148g H2O. 4,1 g of a 25 wt.-% NH3 solution was added to obtain a clear solution with pH 7.
• the Bi-Citrate solution was impregnated by incipient wetness impregnation on 234 g of a silica-alumina, SIRA- LOX5, containing 5 wt.-% S1O2 (in dried powder form). The product was calcined at 550°C for 3h.
• a bismuth oxide doped lanthanum doped alumina with 4 wt.-% B12O3 was prepared ac cording to US 7,611 ,680 B2 Example 3.
• La doped alumina To 2 g of a La doped alumina was added a solution of 0.111 g Bi-acetate in 4 ml H2O and 1ml glacial acetic acid. The resulting paste was mechanically mixed at room tem perature for 60 minutes, dried at 130°C for 2.5 h, ground into a fine powder, and cal cined at 500°C for 1h. The material contained 3 wt.% La2C>3.
• a bismuth oxide doped silica-alumina with 3 wt.-% B12O3 was prepared according to WO 2017/064498 Example 3.
• An aqueous suspension of 40 g silica-alumina containing 5 wt.-% S1O2 was wet-milled to a d90 of 19pm.
• a solution of 2.1 g bismuth-nitrate in diluted nitric acid was added.
• the mixture was spray dried and calcined at 500°C.
• Example 3 (aluminum containing composition comprising silica containing aluminum ox ide)
• a Bi-Citrate solution was prepared by adding 3,7 g Bi-Citrate to 16,1 g H2O. 1 ,2 g of a 25 wt.-% NH3 solution was added to obtain a clear solution with pH 7.
• the Bi-Citrate solution was impregnated on 18 g of a dried powder of silica-alumina, Sl- RALOX 5, containing 5 wt.-% SiC>2.
• the product was calcined at 550°C for 3h.
• a bismuth oxide doped silica-alumina with 10 wt.-% B12O3 was prepared according to WO 2017/064498 Example 15.
• compositions prepared according to the present invention are characterized by substantially smaller crystallinity values regarding the B C when compared to the compositions prepared according to the prior art.

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• 2019
  • 2019-11-29 EP EP19212712.4A patent/EP3827897A1/en not_active Withdrawn
• 2020
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