WO2008056867A1 - Particualte matter and hydrocarbon reduction catalyst at low temperature and preparation method the same - Google Patents

Particualte matter and hydrocarbon reduction catalyst at low temperature and preparation method the same Download PDF

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Publication number
WO2008056867A1
WO2008056867A1 PCT/KR2007/003373 KR2007003373W WO2008056867A1 WO 2008056867 A1 WO2008056867 A1 WO 2008056867A1 KR 2007003373 W KR2007003373 W KR 2007003373W WO 2008056867 A1 WO2008056867 A1 WO 2008056867A1
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Prior art keywords
composite catalyst
metal
platinum
catalyst
lanthanum
Prior art date
Application number
PCT/KR2007/003373
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French (fr)
Inventor
Min-Yong Kim
Moon-Chan Kim
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End Solution Inc.
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Priority claimed from KR1020060109189A external-priority patent/KR20060123679A/en
Application filed by End Solution Inc. filed Critical End Solution Inc.
Publication of WO2008056867A1 publication Critical patent/WO2008056867A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/03—Precipitation; Co-precipitation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • 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
    • B01J23/63—Platinum group metals with rare earths or actinides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • B01J37/0219—Coating the coating containing organic compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • B01J37/0225—Coating of metal substrates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/206—Rare earth metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20707—Titanium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/92—Dimensions
    • B01D2255/9205—Porosity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
    • 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

Definitions

  • the present invention relates to a composite catalyst, which comprises titanium, a platinum-group metal and a lanthanum series metal, and has excellent ability to oxidize particulate matter (PM) and soot into carbon dioxide and oxidize hydrocarbons and carbon monoxide into water and carbon dioxide at low temperatures, as well as a preparation method thereof.
  • PM particulate matter
  • the present invention has been made in order to solve the above-described problems occurring in the prior art, and it is an object of the present invention to provide a composite catalyst, which can reduce the load of trapped soot in a metal foam or a ceramic filter by oxidizing the trapped soot continuously starting from low temperatures, can continuously remove soot and particulate matter (PM) at low temperatures without causing damage to a metal foam or a ceramic filter, because it shows a balance point temperature (BPT) (the temperature at which the trapped soot and the soot being removed are balanced) lower than 270 0 C, and also oxidizes hydrocarbons and carbon monoxide, as well as a preparation method thereof.
  • BPT balance point temperature
  • the present invention provides a Ti-A-B composite catalyst for removing particulate matter (PM) and hydrocarbons at low temperatures, wherein A is at least one platinum-group metal selected from among platinum (Pt), ruthenium (Ru), iridium (Ir) and palladium (Pd), and B is at least one lanthanum series metal selected from among lanthanum (La), cerium (Ce) and samarium (Sm).
  • A is at least one platinum-group metal selected from among platinum (Pt), ruthenium (Ru), iridium (Ir) and palladium (Pd)
  • B is at least one lanthanum series metal selected from among lanthanum (La), cerium (Ce) and samarium (Sm).
  • the present invention provides a method for preparing a Ti-A-B composite catalyst for removing particulate matter and hydrocarbons at low temperatures, the method comprising: mixing a titanium (Ti) compound selected from among TiCl and titanium tetraisopropoxide, with a compound of at least one platinum-group metal (A), selected from among platinum (Pt), ruthenium (Ru), iridium (Ir) and palladium (Pd), and at least one lanthanum series metal (B), selected from among lanthanum (La), cerium (Ce) and samarium (Sm); and stirring the mixture in an aqueous solution of hydrochloric acid, sulfuric acid or nitric acid at 60-150 0 C at 60 rpm or more for more than 3 hours.
  • the Ti-A-B composite catalyst according to the present invention has an excellent effect of oxidizing particulate matter, hydrocarbons, carbon monoxide and the like at low temperatures. Also, the composite catalyst of the present invention shows a balance point temperature (BPT) lower than that of the prior catalysts, and thus provides the effect of continuously removing particulate matter and hydrocarbons even at temperatures lower than 270 0 C. Accordingly, when the composite catalyst of the present invention is applied to a diesel particulate filter (PDPF), a partial diesel particulate filter (DPPF), a diesel oxidation catalyst (DOC) or the like, it can show an excellent effect on the treatment of car exhaust gas. Best Mode for Carrying Out the Invention
  • Ti titanium
  • titanium tetraisopropoxide is mixed with a compound of at least one platinum-group metal (A) selected among from platinum (Pt), ruthenium (Ru), iridium (Ir) and palladium (Pd), and at least one lanthanum series metal (B) selected from lanthanum (La), cerium (Ce) and samarium (Sm).
  • A platinum-group metal
  • Ru ruthenium
  • Ir iridium
  • Pd palladium
  • B lanthanum series metal
  • La lanthanum
  • Ce cerium
  • Sm samarium
  • alcohol such as ethanol, isopropyl alcohol or propanol
  • silane such as hexamethyldisilane, phenylmethylsilane or methyltrimethoxysilane
  • Fe-Cr-Al or stainless, or a foam or filter of ceramic material is dried at 110 0 C for more than 6 hours, and is calcined at 300-600 0 C for 2 hours, thus obtaining a Ti-A-B composite catalyst foam or a Ti-A-B composite catalyst filter for removing particulate matter at low temperatures.
  • preferred examples of the compound of metal (A) include, but are not limited to, platinum metal compounds such as chloroplatinic acid or dinitrodiamine platinate, ruthenium metal compounds such as ruthenium chloride, iridium metal compounds such as iridium chloride, and palladium metal compounds such as palladium chloride or palladium nitrate.
  • Preferred examples of the compound of metal (B) include, but are not limited to, lanthanum metal compounds such as lanthanum nitrate, cerium metal compounds such as cerium nitrate, and samarium metal compounds such as samarium nitrate.
  • the ratio of Ti metal to metals A and B is in the range of 1:1 to 100:1. Also, the weight ratio of metal A to metal B is in the range of 10: 1 to 1 : 10. If the weight ratio between the metals deviates from the above-specified range, the resulting catalyst will have reduced oxidation ability, and thus the effect thereof on the conversion of soot or particulate matter into carbon dioxide will be significantly reduced. If the metal A consists of two or more metals, the weight ratio between the components of the metal A in the Ti-A-B composite catalyst is not limited. Also, if the metal B consists of two or more metals, the weight ratio between the components of the metal B in the Ti-A-B composite catalyst is not limited.
  • the weight ratio of the aqueous solution of hydrochloric acid, sulfuric acid or nitric acid relative to the metals A and B is in the range of 100: 1 to 1 : 1. If the amount of acid aqueous solution used deviates from the specified weight ratio, it will be difficult to produce the composite catalyst, making it difficult to achieve the object of the present invention.
  • alcohol such as ethanol or isopropyl alcohol is used in a weight ratio of
  • silane such as hexamethyldisilane, phenyl- methylsilane or methyltrimethoxysilane.
  • the mixture of alcohol, such as ethanol or isopropyl alcohol, with silane, such as hexamethyldisilane, phenylmethylsilane or methyltrimethoxysilane is used in a weight ratio of 50:1 to 1:50 with respect to the weight of the catalyst coating solution, consisting of the Ti-A-B composite catalyst and the aqueous solution of hydrochloric acid, sulfuric acid or nitric acid.
  • the catalyst coating solution will show significantly reduced adhesion to a metal or alloy of Fe-Cr-Al or stainless material, or a foam or filter of ceramic material, leading to a reduction in durability.
  • Comparative Example 1 relates to a Ti-A catalyst, Comparative Example 2 to a Ti-B catalyst, Comparative Example 3 to an A-B catalyst, and Comparative Example 4 to a Ti-A-B catalyst, prepared without using alcohol, such as ethanol, isopropyl alcohol or propanol, or silane, such as hexamethyldisilane, phenyl- methylsilane or methyltrimethoxysilane, unlike Examples 1-4. Comparative Examples 1-4 were tested for BPT and the efficiency of removal of particulate matter, hydrocarbons and carbon monoxide.
  • the coating solution was impregnated into two pieces of foam having a porosity of 30 PPI and three pieces of foam having a porosity of 50 PPI, each of the pieces of foam having a diameter of 7 inches and a thickness of 1 inch, and being made of Fe-Cr-Al material.
  • the impregnated coating solution was dried at 110 0 C for 6 hours and calcined at 400 0 C for 2 hours, thus obtaining pieces of Ti-Pt-La composite catalyst foam for removing soot and particulate matter at low temperatures.
  • the two pieces of foam having a porosity of 30 PPI and the three pieces of foam having a porosity of 50 PPI were connected to each other in series.
  • the foam structure was measured for BPT, after being subjected to engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and was measured for the rates of removal of particulate matter, hydrocarbons and carbon monoxide, after operation in the ND- 13 mode.
  • Ti-A-B composite catalyst 100 g of titanium triisopropoxide as the Ti metal was mixed with 5 g of ruthenium chloride as the platinum-group metal (A) and 5 g of cerium nitrate as the lanthanum-group metal (B), and 500 g of 10% sulfuric acid aqueous solution was added thereto. The mixture was stirred at 90 0 C at 600 rpm for 3 hours, thus preparing a Ti-Ru-Ce composite catalyst. To the composite catalyst, 10 g of isopropyl alcohol as alcohol and 1O g of phenylmethylsilane as silane were added to prepare a Ti-Ru-Ce composite catalyst coating solution.
  • the coating solution was impregnated into two pieces of foam having a porosity of 30 PPI and three pieces of foam having a porosity of 50 PPI, each of the pieces of foam having a diameter of 7 inches and a thickness of 1 inch and being made of Fe-Cr-Al material.
  • the impregnated coating solution was dried at 110 0 C for 6 hours and calcined at 400 0 C for 2 hours, thus obtaining pieces of Ti-Cr-Ce composite catalyst foam for removing soot and particulate matter at low temperatures.
  • the two pieces of foam having a porosity of 30 PPI and the three pieces of foam having a porosity of 50 PPI were connected to each other in series.
  • the foam structure was measured for BPT, after being subjected to engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and was measured for the rates of removal of particulate matter, hydrocarbons and carbon monoxide, after operation in the ND- 13 mode.
  • Ti-A-B composite catalyst 100 g of titanium triisopropoxide as the Ti metal was mixed with 5 g of iridium chloride as the platinum-group metal (A) and 5 g of samarium nitrate as the lanthanum-group metal (B), and 500 g of 10% nitric acid aqueous solution was added thereto. The mixture was stirred at 90 0 C at 600 rpm for 3 hours, thus preparing a Ti-Ir-Sm composite catalyst. To the composite catalyst, 10 g of propanol as alcohol and 10 g of methyltrimethoxysilane as silane were added to prepare a Ti-Ir-Sm composite catalyst coating solution.
  • the coating solution was impregnated into two pieces of foam having a porosity of 30 PPI and three pieces of foam having a porosity of 50 PPI, each of the pieces of foam having a diameter of 7 inches and a thickness of 1 inch and made of Fe-Cr-Al material.
  • the impregnated coating solution was dried at 110 0 C for 6 hours and calcined at 400 0 C for 2 hours, thus obtaining pieces of Ti-Ir-Sm composite catalyst foam for removing soot and particulate matter at low temperatures.
  • the two pieces of foam having a porosity of 30 PPI and the three pieces of foam having a porosity of 50 PPI were connected to each other in series.
  • the foam structure was measured for BPT, after being subjected to engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and was measured for the rates of removal of particulate matter, hydrocarbons and carbon monoxide, after operation in the ND- 13 mode.
  • the impregnated coating solution was dried at 110 0 C for 6 hours and calcined at 400 0 C for 2 hours, thus obtaining Ti-Ir-Sm composite catalyst foams for removing soot and particulate matter at low temperatures.
  • the three catalyst- coated stainless honeycombs were connected to each other in series. Then, the honeycomb structure was measured for BPT after being subjected an engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and was measured for the rates of removal of particulate matter, hydrocarbons and carbon monoxide, after operation in the ND- 13 mode.
  • Ti-A-B composite catalyst 100 g of titanium triisopropoxide as the Ti metal was mixed with 3 g of dinitrodiamine platinate and 2 g of iridium chloride, as the platinum-group metals (A), and 3 g of samarium nitrate and 2 g of lanthanum nitrate, as the lanthanum-group metals (B), and 500 g of 10% nitric acid aqueous solution was added thereto. The mixture was stirred at 90 0 C at 600 rpm for 3 hours, thus preparing a Ti-Pt-Ir-Sm-La composite catalyst.
  • Ti-Pt-Ir-Sm-La composite catalyst coating solution 10 g of propanol as alcohol and 10 g of methyltrimethoxysilane as silane were added to prepare a Ti-Pt-Ir-Sm-La composite catalyst coating solution.
  • the coating solution was impregnated into a filter containing 30-mesh SiC particles in a housing having a diameter of 10.5 inches and a depth of 15 inches.
  • the impregnated coating solution was dried at 110 0 C for 6 hours and calcined at 400 0 C for 2 hours, thus obtaining a Ti- Pt-Ir-Sm-La composite SiC filter.
  • the filter was measured for BPT, after being subjected to engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and was measured for the rates of removal of particulate matter, hydrocarbons and carbon monoxide, after operation in the ND- 13 mode.
  • a Ti-A composite catalyst was prepared in the same manner as in Example 1, except that 100 g of TiCl as the Ti metal and 5 g of chloroplatinic acid as the
  • a Ti-B composite catalyst was prepared in the same manner as in Example 2, except that 100 g of titanium triisopropoxide as the Ti metal and 5 g of cerium nitrate as the lanthanum-group metal (B) were used, and the metal A was not used.
  • An A-B composite catalyst was prepared in the same manner as in Example 1, except that 5 g of chloroplatinic acid as the platinum-group metal (A) and 5 g of lanthanum nitrate as the lanthanum-group metal were used, and no Ti metal was used.
  • a Ti-A-B composite catalyst was prepared in the same manner as in Example 1, except that neither ethanol as alcohol nor hexamethyldisilane as silane was used.
  • Table 1 shows the constructions of the Ti-A-B composite catalysts. Also, Table 1 shows BPT (balance point temperature), measured after being subjected to an engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and the rates of removal of particulate matter, hydrocarbons and carbon monoxide, measured after operation in the ND- 13 mode. A lower BPT (balance point temperature) shows a better ability to continuously remove particulate matter (PM) at low temperatures so as to remove soot and hydrocarbons.
  • BPT balance point temperature
  • the composite catalyst according to the present invention can be used in systems for treating diesel exhaust gases. More specifically, the inventive composite catalyst can be used in exhaust gas treatment systems including a diesel particulate filter (DPF), a partial diesel particulate filter (PDPF) and a diesel oxidation catalyst (DOC).
  • DPF diesel particulate filter
  • PDPF partial diesel particulate filter
  • DOC diesel oxidation catalyst

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  • Organic Chemistry (AREA)
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Abstract

Disclosed herein are a composite catalyst for oxidizing particulate matter (PM), soot, hy¬ drocarbons, carbon monoxide and the like into carbon dioxide and water at low temperatures, as well as a preparation method thereof. According to the disclosed invention, a Ti-A-B composite catalyst is prepared by mixing titanium with at least one platinum-group metal (A) selected among from platinum (Pt), ruthenium (Ru), iridium (Ir) and palladium (Pd), and at least one lanthanum series metal (B) selected from among lanthanum (La), cerium (Ce) and samarium (Sm). The prepared Ti-A-B composite catalyst can be coated on a porous foam of Fe-Cr-Al or stainless material or a ceramic filter to manufacture a catalyst system. When the catalyst system is applied to the treatment of car exhaust gases, it has an excellent effect of oxidizing particulate matter, hydrocarbonhydrocarbons, hydrocarbons, carbon monoxide and the like at low tem¬ peratures.

Description

Description
PARTICULATE MATTER AND HYDROCARBON REDUCTION CATALYST AT LOW TEMPERATURE AND PREPARATION
METHOD THE SAME
Technical Field
[1] The present invention relates to a composite catalyst, which comprises titanium, a platinum-group metal and a lanthanum series metal, and has excellent ability to oxidize particulate matter (PM) and soot into carbon dioxide and oxidize hydrocarbons and carbon monoxide into water and carbon dioxide at low temperatures, as well as a preparation method thereof. Background Art
[2] In diesel exhaust gas treatment technology according to the prior art, a particulate catalyst system, comprising refractory inorganic compound alumina, wash-coated on a ceramic filter, and platinum supported on the alumina, has been used. However, in this filter system, rapid oxidation may frequently occur at temperatures higher than 350 0C after catalyst system traps soot and particulate matter. This causes local overheating, which causes the ceramic filter to melt or break, with the result that soot and particulate matter cannot be removed through the filter system. Accordingly, the prior catalyst system has a problem in that it cannot achieve sufficient removal of soot and particulate matter. Disclosure of Invention Technical Problem
[3] The present invention has been made in order to solve the above-described problems occurring in the prior art, and it is an object of the present invention to provide a composite catalyst, which can reduce the load of trapped soot in a metal foam or a ceramic filter by oxidizing the trapped soot continuously starting from low temperatures, can continuously remove soot and particulate matter (PM) at low temperatures without causing damage to a metal foam or a ceramic filter, because it shows a balance point temperature (BPT) (the temperature at which the trapped soot and the soot being removed are balanced) lower than 270 0C, and also oxidizes hydrocarbons and carbon monoxide, as well as a preparation method thereof. Technical Solution
[4] To achieve the above object, in one aspect, the present invention provides a Ti-A-B composite catalyst for removing particulate matter (PM) and hydrocarbons at low temperatures, wherein A is at least one platinum-group metal selected from among platinum (Pt), ruthenium (Ru), iridium (Ir) and palladium (Pd), and B is at least one lanthanum series metal selected from among lanthanum (La), cerium (Ce) and samarium (Sm).
[5] In another aspect, the present invention provides a method for preparing a Ti-A-B composite catalyst for removing particulate matter and hydrocarbons at low temperatures, the method comprising: mixing a titanium (Ti) compound selected from among TiCl and titanium tetraisopropoxide, with a compound of at least one platinum-group metal (A), selected from among platinum (Pt), ruthenium (Ru), iridium (Ir) and palladium (Pd), and at least one lanthanum series metal (B), selected from among lanthanum (La), cerium (Ce) and samarium (Sm); and stirring the mixture in an aqueous solution of hydrochloric acid, sulfuric acid or nitric acid at 60-150 0C at 60 rpm or more for more than 3 hours.
Advantageous Effects
[6] The Ti-A-B composite catalyst according to the present invention has an excellent effect of oxidizing particulate matter, hydrocarbons, carbon monoxide and the like at low temperatures. Also, the composite catalyst of the present invention shows a balance point temperature (BPT) lower than that of the prior catalysts, and thus provides the effect of continuously removing particulate matter and hydrocarbons even at temperatures lower than 270 0C. Accordingly, when the composite catalyst of the present invention is applied to a diesel particulate filter (PDPF), a partial diesel particulate filter (DPPF), a diesel oxidation catalyst (DOC) or the like, it can show an excellent effect on the treatment of car exhaust gas. Best Mode for Carrying Out the Invention
[7] To prepare the inventive catalyst for removing particulate matter and hydrocarbons at low temperatures, a titanium (Ti) compound, selected from among TiCl and
4 titanium tetraisopropoxide, is mixed with a compound of at least one platinum-group metal (A) selected among from platinum (Pt), ruthenium (Ru), iridium (Ir) and palladium (Pd), and at least one lanthanum series metal (B) selected from lanthanum (La), cerium (Ce) and samarium (Sm). The mixture is stirred in an aqueous solution of hydrochloric acid, sulfuric acid or nitric acid at 60-150 0C at 60 rpm or more for more than 3 hours, thus preparing a Ti-A-B composite catalyst. To the Ti-A-B composite catalyst, alcohol, such as ethanol, isopropyl alcohol or propanol, and silane, such as hexamethyldisilane, phenylmethylsilane or methyltrimethoxysilane, are added to prepare a catalyst coating solution.
[8] The catalyst coating solution thus prepared is impregnated into a metal or alloy of
Fe-Cr-Al or stainless, or a foam or filter of ceramic material, is dried at 110 0C for more than 6 hours, and is calcined at 300-600 0C for 2 hours, thus obtaining a Ti-A-B composite catalyst foam or a Ti-A-B composite catalyst filter for removing particulate matter at low temperatures. In the present invention, preferred examples of the compound of metal (A) include, but are not limited to, platinum metal compounds such as chloroplatinic acid or dinitrodiamine platinate, ruthenium metal compounds such as ruthenium chloride, iridium metal compounds such as iridium chloride, and palladium metal compounds such as palladium chloride or palladium nitrate. Preferred examples of the compound of metal (B) include, but are not limited to, lanthanum metal compounds such as lanthanum nitrate, cerium metal compounds such as cerium nitrate, and samarium metal compounds such as samarium nitrate.
[9] With respect to the weight ratio of metals in the Ti-A-B composite catalyst, the ratio of Ti metal to metals A and B is in the range of 1:1 to 100:1. Also, the weight ratio of metal A to metal B is in the range of 10: 1 to 1 : 10. If the weight ratio between the metals deviates from the above-specified range, the resulting catalyst will have reduced oxidation ability, and thus the effect thereof on the conversion of soot or particulate matter into carbon dioxide will be significantly reduced. If the metal A consists of two or more metals, the weight ratio between the components of the metal A in the Ti-A-B composite catalyst is not limited. Also, if the metal B consists of two or more metals, the weight ratio between the components of the metal B in the Ti-A-B composite catalyst is not limited.
[10] The weight ratio of the aqueous solution of hydrochloric acid, sulfuric acid or nitric acid relative to the metals A and B is in the range of 100: 1 to 1 : 1. If the amount of acid aqueous solution used deviates from the specified weight ratio, it will be difficult to produce the composite catalyst, making it difficult to achieve the object of the present invention.
[11] Meanwhile, alcohol such as ethanol or isopropyl alcohol is used in a weight ratio of
50:1 to 1:50 with respect to the weight of silane, such as hexamethyldisilane, phenyl- methylsilane or methyltrimethoxysilane. Also, the mixture of alcohol, such as ethanol or isopropyl alcohol, with silane, such as hexamethyldisilane, phenylmethylsilane or methyltrimethoxysilane, is used in a weight ratio of 50:1 to 1:50 with respect to the weight of the catalyst coating solution, consisting of the Ti-A-B composite catalyst and the aqueous solution of hydrochloric acid, sulfuric acid or nitric acid. If the weight ratio of the alcohol/silane mixture to the catalyst coating solution deviates from the above-specified range, the catalyst coating solution will show significantly reduced adhesion to a metal or alloy of Fe-Cr-Al or stainless material, or a foam or filter of ceramic material, leading to a reduction in durability.
[12] Hereinafter, the present invention will be described in further detail with reference to examples.
[13] In Examples 1 to 5 below, Ti-A-B composite catalysts having varying constructions were tested for BPT and the efficiency of removal of particulate matter, hydrocarbons and carbon monoxide. Comparative Example 1 relates to a Ti-A catalyst, Comparative Example 2 to a Ti-B catalyst, Comparative Example 3 to an A-B catalyst, and Comparative Example 4 to a Ti-A-B catalyst, prepared without using alcohol, such as ethanol, isopropyl alcohol or propanol, or silane, such as hexamethyldisilane, phenyl- methylsilane or methyltrimethoxysilane, unlike Examples 1-4. Comparative Examples 1-4 were tested for BPT and the efficiency of removal of particulate matter, hydrocarbons and carbon monoxide.
[14] The present invention will now be described in further detail with reference to examples, but the scope of the present invention is not limited only to these examples.
[15] Example 1
[16] To prepare a Ti-A-B composite catalyst, 100 g of TiCl as the Ti metal was mixed
4 with 5 g of chloroplatinic acid as the platinum-group metal (A) and 5 g of lanthanum nitrate as the lanthanum-group metal (B), and 500 g of 10% hydrochloric acid aqueous solution was added thereto. The mixture was stirred at 90 0C at 600 rpm for 3 hours, thus preparing a Ti-Pt-La composite catalyst. To the composite catalyst, 10 g of ethanol as alcohol and 1O g of hexamethyldisilane as silane were added to prepare a Ti- Pt-La composite catalyst coating solution. The coating solution was impregnated into two pieces of foam having a porosity of 30 PPI and three pieces of foam having a porosity of 50 PPI, each of the pieces of foam having a diameter of 7 inches and a thickness of 1 inch, and being made of Fe-Cr-Al material. The impregnated coating solution was dried at 110 0C for 6 hours and calcined at 400 0C for 2 hours, thus obtaining pieces of Ti-Pt-La composite catalyst foam for removing soot and particulate matter at low temperatures. The two pieces of foam having a porosity of 30 PPI and the three pieces of foam having a porosity of 50 PPI were connected to each other in series. Then, the foam structure was measured for BPT, after being subjected to engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and was measured for the rates of removal of particulate matter, hydrocarbons and carbon monoxide, after operation in the ND- 13 mode.
[17] Example 2
[18] To prepare a Ti-A-B composite catalyst, 100 g of titanium triisopropoxide as the Ti metal was mixed with 5 g of ruthenium chloride as the platinum-group metal (A) and 5 g of cerium nitrate as the lanthanum-group metal (B), and 500 g of 10% sulfuric acid aqueous solution was added thereto. The mixture was stirred at 90 0C at 600 rpm for 3 hours, thus preparing a Ti-Ru-Ce composite catalyst. To the composite catalyst, 10 g of isopropyl alcohol as alcohol and 1O g of phenylmethylsilane as silane were added to prepare a Ti-Ru-Ce composite catalyst coating solution. The coating solution was impregnated into two pieces of foam having a porosity of 30 PPI and three pieces of foam having a porosity of 50 PPI, each of the pieces of foam having a diameter of 7 inches and a thickness of 1 inch and being made of Fe-Cr-Al material. The impregnated coating solution was dried at 110 0C for 6 hours and calcined at 400 0C for 2 hours, thus obtaining pieces of Ti-Cr-Ce composite catalyst foam for removing soot and particulate matter at low temperatures. The two pieces of foam having a porosity of 30 PPI and the three pieces of foam having a porosity of 50 PPI were connected to each other in series. Then, the foam structure was measured for BPT, after being subjected to engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and was measured for the rates of removal of particulate matter, hydrocarbons and carbon monoxide, after operation in the ND- 13 mode.
[19] Example 3
[20] To prepare a Ti-A-B composite catalyst, 100 g of titanium triisopropoxide as the Ti metal was mixed with 5 g of iridium chloride as the platinum-group metal (A) and 5 g of samarium nitrate as the lanthanum-group metal (B), and 500 g of 10% nitric acid aqueous solution was added thereto. The mixture was stirred at 90 0C at 600 rpm for 3 hours, thus preparing a Ti-Ir-Sm composite catalyst. To the composite catalyst, 10 g of propanol as alcohol and 10 g of methyltrimethoxysilane as silane were added to prepare a Ti-Ir-Sm composite catalyst coating solution. The coating solution was impregnated into two pieces of foam having a porosity of 30 PPI and three pieces of foam having a porosity of 50 PPI, each of the pieces of foam having a diameter of 7 inches and a thickness of 1 inch and made of Fe-Cr-Al material. The impregnated coating solution was dried at 110 0C for 6 hours and calcined at 400 0C for 2 hours, thus obtaining pieces of Ti-Ir-Sm composite catalyst foam for removing soot and particulate matter at low temperatures. The two pieces of foam having a porosity of 30 PPI and the three pieces of foam having a porosity of 50 PPI were connected to each other in series. Then, the foam structure was measured for BPT, after being subjected to engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and was measured for the rates of removal of particulate matter, hydrocarbons and carbon monoxide, after operation in the ND- 13 mode.
[21] Example 4
[22] To prepare a Ti-A-B composite catalyst, 100 g of TiCl as the Ti metal was mixed
4 with 5 g of palladium chloride as the platinum-group metal (A) and 5 g of samarium nitrate as the lanthanum-group metal (B), and 500 g of 10% nitric acid aqueous solution was added thereto. The mixture was stirred at 90 0C at 600 rpm for 3 hours, thus preparing a Ti-Pd-Sm composite catalyst. To the composite catalyst, 10 g of propanol as alcohol and 10 g of methyltrimethoxysilane as silane were added to prepare a Ti-Pd-Sm composite catalyst coating solution. The coating solution was impregnated into three stainless honeycombs, each having a diameter of 7 inches and a thickness of 6 inches. The impregnated coating solution was dried at 110 0C for 6 hours and calcined at 400 0C for 2 hours, thus obtaining Ti-Ir-Sm composite catalyst foams for removing soot and particulate matter at low temperatures. The three catalyst- coated stainless honeycombs were connected to each other in series. Then, the honeycomb structure was measured for BPT after being subjected an engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and was measured for the rates of removal of particulate matter, hydrocarbons and carbon monoxide, after operation in the ND- 13 mode.
[23] Example 5
[24] To prepare a Ti-A-B composite catalyst, 100 g of titanium triisopropoxide as the Ti metal was mixed with 3 g of dinitrodiamine platinate and 2 g of iridium chloride, as the platinum-group metals (A), and 3 g of samarium nitrate and 2 g of lanthanum nitrate, as the lanthanum-group metals (B), and 500 g of 10% nitric acid aqueous solution was added thereto. The mixture was stirred at 90 0C at 600 rpm for 3 hours, thus preparing a Ti-Pt-Ir-Sm-La composite catalyst. To the composite catalyst, 10 g of propanol as alcohol and 10 g of methyltrimethoxysilane as silane were added to prepare a Ti-Pt-Ir-Sm-La composite catalyst coating solution. The coating solution was impregnated into a filter containing 30-mesh SiC particles in a housing having a diameter of 10.5 inches and a depth of 15 inches. The impregnated coating solution was dried at 110 0C for 6 hours and calcined at 400 0C for 2 hours, thus obtaining a Ti- Pt-Ir-Sm-La composite SiC filter. Then, the filter was measured for BPT, after being subjected to engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and was measured for the rates of removal of particulate matter, hydrocarbons and carbon monoxide, after operation in the ND- 13 mode.
[25] Comparative Example 1
[26] A Ti-A composite catalyst was prepared in the same manner as in Example 1, except that 100 g of TiCl as the Ti metal and 5 g of chloroplatinic acid as the
4 platinum-group metal (A) were used, and the metal B was not used.
[27] Comparative Example 2
[28] A Ti-B composite catalyst was prepared in the same manner as in Example 2, except that 100 g of titanium triisopropoxide as the Ti metal and 5 g of cerium nitrate as the lanthanum-group metal (B) were used, and the metal A was not used.
[29] Comparative Example 3
[30] An A-B composite catalyst was prepared in the same manner as in Example 1, except that 5 g of chloroplatinic acid as the platinum-group metal (A) and 5 g of lanthanum nitrate as the lanthanum-group metal were used, and no Ti metal was used.
[31] Comparative Example 4
[32] A Ti-A-B composite catalyst was prepared in the same manner as in Example 1, except that neither ethanol as alcohol nor hexamethyldisilane as silane was used.
[33] Test Example [34] Table 1 below shows the constructions of the Ti-A-B composite catalysts. Also, Table 1 shows BPT (balance point temperature), measured after being subjected to an engine dynamometer aging in the Engelhard mode using a 3900-cc engine for 200 hours, and the rates of removal of particulate matter, hydrocarbons and carbon monoxide, measured after operation in the ND- 13 mode. A lower BPT (balance point temperature) shows a better ability to continuously remove particulate matter (PM) at low temperatures so as to remove soot and hydrocarbons.
[35] Table 1
BPT and removal rates of PM/hydrocarbon/carbon monoxide of catalysts according to Examples
Figure imgf000008_0001
[36]
Industrial Applicability [37] The composite catalyst according to the present invention can be used in systems for treating diesel exhaust gases. More specifically, the inventive composite catalyst can be used in exhaust gas treatment systems including a diesel particulate filter (DPF), a partial diesel particulate filter (PDPF) and a diesel oxidation catalyst (DOC).

Claims

Claims
[1] A Ti-A-B composite catalyst for removing particulate matter (PM) and hydrocarbons at low temperatures, wherein A is at least one platinum-group metal selected from among platinum (Pt), ruthenium (Ru), iridium (Ir) and palladium (Pd), and B is at least one lanthanum series metal selected from among lanthanum (La), cerium (Ce) and samarium (Sm).
[2] The catalyst of Claim 1, wherein the weight ratio of (A+B): Ti in the Ti-A-B composite catalyst is 1 : 1-100, and the weight ratio of A: B ranges from 10: 1 to 1:10.
[3] A method for preparing a Ti-A-B composite catalyst for removing particulate matter (PM) and hydrocarbons at low temperatures, the method comprising: mixing a titanium (Ti) compound selected from among TiCl and titanium tetraisopropoxide with a compound of at least one platinum-group metal (A) selected from among platinum (Pt), ruthenium (Ru), iridium (Ir) and palladium (Pd), and at least one lanthanum series metal (B) selected from among lanthanum (La), cerium (Ce) and samarium (Sm); and stirring the mixture in an aqueous solution of hydrochloric acid, sulfuric acid or nitric acid at 60-150 0C at 60 rpm or more for more than 3 hours.
[4] The method of Claim 3, further comprising adding, to the prepared Ti-A-B composite catalyst, an alcohol selected from among ethanol, isopropyl alcohol and propanol, and a silane selected from among hexamethyldisilane, phenyl- methylsilane and methyltrimethoxysilane.
[5] The method of Claim 3, wherein the aqueous solution of hydrochloric acid, sulfuric acid or nitric acid is used in an amount of 1-100 parts by weight based on 1 part by weight of the sum of the Ti, the metal A and the metal B.
[6] The method of Claim 4, wherein the alcohol is used in a weight ratio ranging from 50:1 to 1: 50 with respect to the silane.
[7] The method of Claim 4, wherein the ratio of the total weight of alcohol and silane relative to the total weight of the Ti-A-B composite catalyst and the aqueous solution of hydrochloric acid, sulfuric acid and nitric acid ranges from 50:1 to 1:50.
[8] A Ti-A-B composite catalyst system for removing particulate matter (PM) and hydrocarbons at low temperatures, the composite catalyst system being manufactured by: mixing a titanium (Ti) compound selected from among TiCl and titanium tetraisopropoxide, with a compound of at least one platinum-group metal (A) selected among from platinum (Pt), ruthenium (Ru), iridium (Ir) and palladium (Pd), and at least one lanthanum series metal (B) selected from among lanthanum (La), cerium (Ce) and samarium (Sm); stirring the mixture in an aqueous solution of hydrochloric acid, sulfuric acid or nitric acid at 60-150 0C at 60 rpm or more for more than 3 hours, thus preparing a Ti-A-B composite catalyst; adding, to the Ti-A-B composite catalyst, an alcohol selected from among ethanol, isopropyl alcohol and propanol, and a silane selected from among hex- amethyldisilane, phenylmethylsilane and methyltrimethoxysilane, thus preparing a catalyst coating solution; impregnating the catalyst coating solution into a metal or alloy of Fe-Cr-Al or stainless material or a foam or filter of SiC or ceramic material; drying the impregnated structure at 110 0C for more than 6 hours; and calcining the dried structure at 300-600 0C for more than 2 hours.
[9] The composite catalyst system of Claim 8, which is a diesel particulate filter
(PDPF), a partial diesel particulate filter (DPPF), or a diesel oxidation catalyst (DOC).
PCT/KR2007/003373 2006-11-07 2007-07-12 Particualte matter and hydrocarbon reduction catalyst at low temperature and preparation method the same WO2008056867A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5071816A (en) * 1989-05-08 1991-12-10 Nippon Shokubai Kagaku Kogyo Co., Ltd. Catalyst for purification of exhaust gas from diesel engine
KR19980082742A (en) * 1997-05-09 1998-12-05 김영귀 Oxidation catalyst for reducing particulate matter in diesel engines
KR20050087218A (en) * 2004-02-26 2005-08-31 (주) 세라컴 Method for preparing a catalyst for diesel engine off gas purification and the catalyst prepared from the method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5071816A (en) * 1989-05-08 1991-12-10 Nippon Shokubai Kagaku Kogyo Co., Ltd. Catalyst for purification of exhaust gas from diesel engine
KR19980082742A (en) * 1997-05-09 1998-12-05 김영귀 Oxidation catalyst for reducing particulate matter in diesel engines
KR20050087218A (en) * 2004-02-26 2005-08-31 (주) 세라컴 Method for preparing a catalyst for diesel engine off gas purification and the catalyst prepared from the method

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