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WO1996035510A1 - Carbides and nitrides of transition elements with controlled porosity - Google Patents

Carbides and nitrides of transition elements with controlled porosity Download PDF

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Publication number
WO1996035510A1
WO1996035510A1 PCT/BR1996/000011 BR9600011W WO9635510A1 WO 1996035510 A1 WO1996035510 A1 WO 1996035510A1 BR 9600011 W BR9600011 W BR 9600011W WO 9635510 A1 WO9635510 A1 WO 9635510A1
Authority
WO
WIPO (PCT)
Prior art keywords
nitrides
carbides
transition elements
porous
preparation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/BR1996/000011
Other languages
French (fr)
Inventor
José Augusto Jorge RODRIGUES
Gilberto Marques Cruz
Gérald DJEGA-MARIADASSOU
Guy Bugli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
INSTITUTO NACIONAL DE PESQUISAS ESPACIAIS
Original Assignee
INSTITUTO NACIONAL DE PESQUISAS ESPACIAIS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by INSTITUTO NACIONAL DE PESQUISAS ESPACIAIS filed Critical INSTITUTO NACIONAL DE PESQUISAS ESPACIAIS
Priority to JP8533616A priority Critical patent/JPH11510427A/en
Priority to EP96905624A priority patent/EP0824371A1/en
Publication of WO1996035510A1 publication Critical patent/WO1996035510A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/20—Carbon compounds
    • B01J27/22—Carbides
    • 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
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/24—Nitrogen 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
    • 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
    • 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
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
    • 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
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/64—Pore diameter
    • B01J35/647—2-50 nm
    • 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
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/66—Pore distribution
    • B01J35/69—Pore distribution bimodal

Definitions

  • the present invention relates to a preparation method of carbides and nitrides of transition elements in extruded shape from their oxides, leading to a controlled porous volume and distribution, destinated to catalytic use like in isomerization or hydrogenation reactions or in reactions used to gas generation like hydrazine decomposition in propulsion systems .
  • Carbides and nitrides are interstitial alloys formed by incorporating carbon and nitrogen into the cristalline nets of the transition metals oxide. These alloys show metallic characteristics which give them catalytic activity similar to various metals, like iridium, platinum and paladium. The important characteristics of such compounds, besides being extremely hard, are corrosion resistance and high melting point. As direct consequence of these properties carbides and nitrides are used not only in catalysis, but also in cutting tools, structural parts, etc. The use in catalysis came from the development by Boudart team of a preparation method which resulted in carbides and nitrides of high specific area.
  • This preparation method consists of a reduction of oxide of the transition metal, using gaseous amonia for that in the nitrides case or a hydrogen and methane mixture in the carbides case, and increasing the temperature of the precursor oxide in a uniform and smooth way.
  • This preparation method produces materials with high specific area, the obtained porous structure can not be controlled, leading to a porous diameter not higher than 50 angstroms.
  • the invention herein is different from the nowadays existing techniques by the possibility of obtaining carbides and nitrides of transition elements in the extruded shape with the intended porosity.
  • the preparation method consists in obtaining the transition elements acids, tungstic for the tungsten and molybdic for the molybdenum, in a peptizable shape. These acids which were obtained in the colloidal shape when formed at low temperatures, in powder shape, are mixtured with microcrystalline cellulose, also in powder shape.
  • the mixture is peptized using as a peptization agent an ammonium hydroxide dilluted solution.
  • the obtained product is then extruded with the aid of an extruder.
  • the thermal treatment of the extruded product involves drying at 60°C and after at 120°C, both during approximately 12 hours. After that a calcination at 600°C, during 3 hours, is made with the goal of transforming the acid in its corresponding oxide and to burn the cellulose remaining in the acid.
  • the ellimination of this cellulose generates, in the resulting oxide, a porosity that can be controlled by concentrating this compound mixtured with the acid or by the ammonium hydroxide content used as the peptizing agent.
  • Figure 1 shows the porous structure obtained by this method for the molybdenum carbide_case.
  • the Y axis is the incremental specific volume (dV/dD) in cm /g, where V is the porous specific volume and D is the porous diameter.
  • X axis the porous diameter, in angstroms, is shown in a logarithmic scale.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Catalysts (AREA)
  • Ceramic Products (AREA)
  • Carbon And Carbon Compounds (AREA)

Abstract

The present invention relates to a preparation method of carbides and nitrides of transition elements in extruded shape and from their oxides, with controlled porous volume and distribution. The meso and macroporous are generated by polymeric organic molecules such as microcrystalline cellulose, which after being burned form a more opened porous structure. The molding process involves the obtention of intermediate compounds that are susceptible to peptization and later extrusion. The preparation of these compounds, with porous diameter greater than 50 angstroms, implies in a range of catalytic reactions applications since more opened porous structures allow the catalytic process of larger molecules. Besides, in this way, there are less problems related to heat and mass diffusion processes. Problems which appear when dealing with very active catalysts and/or very exothermic reactions.

Description

Descriptive Report of the Patent of Invention "CARBIDES AND NITRIDES OF TRANSITION ELEMENTS WITH CONTROLLED POROSITY" . The present invention relates to a preparation method of carbides and nitrides of transition elements in extruded shape from their oxides, leading to a controlled porous volume and distribution, destinated to catalytic use like in isomerization or hydrogenation reactions or in reactions used to gas generation like hydrazine decomposition in propulsion systems .
Carbides and nitrides are interstitial alloys formed by incorporating carbon and nitrogen into the cristalline nets of the transition metals oxide. These alloys show metallic characteristics which give them catalytic activity similar to various metals, like iridium, platinum and paladium. The important characteristics of such compounds, besides being extremely hard, are corrosion resistance and high melting point. As direct consequence of these properties carbides and nitrides are used not only in catalysis, but also in cutting tools, structural parts, etc. The use in catalysis came from the development by Boudart team of a preparation method which resulted in carbides and nitrides of high specific area. This preparation method consists of a reduction of oxide of the transition metal, using gaseous amonia for that in the nitrides case or a hydrogen and methane mixture in the carbides case, and increasing the temperature of the precursor oxide in a uniform and smooth way. Although this preparation method produces materials with high specific area, the obtained porous structure can not be controlled, leading to a porous diameter not higher than 50 angstroms. The invention herein is different from the nowadays existing techniques by the possibility of obtaining carbides and nitrides of transition elements in the extruded shape with the intended porosity. The preparation method consists in obtaining the transition elements acids, tungstic for the tungsten and molybdic for the molybdenum, in a peptizable shape. These acids which were obtained in the colloidal shape when formed at low temperatures, in powder shape, are mixtured with microcrystalline cellulose, also in powder shape.
After this phase the mixture is peptized using as a peptization agent an ammonium hydroxide dilluted solution. The obtained product is then extruded with the aid of an extruder. The thermal treatment of the extruded product involves drying at 60°C and after at 120°C, both during approximately 12 hours. After that a calcination at 600°C, during 3 hours, is made with the goal of transforming the acid in its corresponding oxide and to burn the cellulose remaining in the acid. The ellimination of this cellulose generates, in the resulting oxide, a porosity that can be controlled by concentrating this compound mixtured with the acid or by the ammonium hydroxide content used as the peptizing agent. After this phase the carbides and nitrides are obtained by heating these precursors in a uniform and smooth way in a gaseous amonia environment, for nitrides, or in a hydrogen and methane environment, for carbides. TIPICAL EXAMPLE
Figure 1 shows the porous structure obtained by this method for the molybdenum carbide_case. The Y axis is the incremental specific volume (dV/dD) in cm /g, where V is the porous specific volume and D is the porous diameter. In X axis the porous diameter, in angstroms, is shown in a logarithmic scale. The mode 1 shown in figure as region 1 has coordinates X=40 and Y=0.08 and represents the porosity generated during the precursor oxide transformation in carbide or nitride. The mode 2, having as coordinates X=1000 and Y=0.15, represents the porosity generated by the burning of polymeric materials and their X and Y values depend on the content and kind of the employed polymer.

Claims

1 - Carbides and nitrides of transition elements characterized by the obtention of these compounds with controlled porous volume and distribution, used to catalitic applications in_general.
2 - Carbides and nitrides of transition elements as in claim 1, characterized by the use of long chain materials susceptible to combustion, used for generation of meso and macroporous, such_as microcrystalline cellulose.
3 - Carbides and nitrides of transition elements as in claim 1, characterized by the use of amonium hydroxide as peptizing agent in the molding process extruded products obtention - of the carbides and nitrides precursors.
PCT/BR1996/000011 1995-05-11 1996-03-19 Carbides and nitrides of transition elements with controlled porosity Ceased WO1996035510A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP8533616A JPH11510427A (en) 1995-05-11 1996-03-19 Controlled porosity transition element carbides and nitrides
EP96905624A EP0824371A1 (en) 1995-05-11 1996-03-19 Carbides and nitrides of transition elements with controlled porosity

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BR9501693A BR9501693A (en) 1995-05-11 1995-05-11 Carbides and nitrides of transition elements with controlled porosity
BRPI9501693-7 1995-05-11

Publications (1)

Publication Number Publication Date
WO1996035510A1 true WO1996035510A1 (en) 1996-11-14

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PCT/BR1996/000011 Ceased WO1996035510A1 (en) 1995-05-11 1996-03-19 Carbides and nitrides of transition elements with controlled porosity

Country Status (5)

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EP (1) EP0824371A1 (en)
JP (1) JPH11510427A (en)
BR (1) BR9501693A (en)
CA (1) CA2219797A1 (en)
WO (1) WO1996035510A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10002117A1 (en) * 2000-01-20 2001-08-16 Geesthacht Gkss Forschung Catalysis of the hydrogen sorption kinetics of hydrides by nitrides and carbides

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4271041A (en) * 1979-02-08 1981-06-02 The Board Of Trustees Of Leland Stanford Junior University High surface area molybdenum oxycarbide catalysts
US4851206A (en) * 1981-07-15 1989-07-25 The Board Of Trustees Of The Leland Stanford Junior University, Stanford University Methods and compostions involving high specific surface area carbides and nitrides
US4940684A (en) * 1987-09-28 1990-07-10 President Of Agency Of Industrial Science And Technology Method for preparing a catalyst supported on silicon carbide or silicon nitride
US5139987A (en) * 1990-09-06 1992-08-18 Pechiney Recherche Process for activating the surface of carbides of heavy metals with a large specific surface for catalytic reactions

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4271041A (en) * 1979-02-08 1981-06-02 The Board Of Trustees Of Leland Stanford Junior University High surface area molybdenum oxycarbide catalysts
US4851206A (en) * 1981-07-15 1989-07-25 The Board Of Trustees Of The Leland Stanford Junior University, Stanford University Methods and compostions involving high specific surface area carbides and nitrides
US4940684A (en) * 1987-09-28 1990-07-10 President Of Agency Of Industrial Science And Technology Method for preparing a catalyst supported on silicon carbide or silicon nitride
US5139987A (en) * 1990-09-06 1992-08-18 Pechiney Recherche Process for activating the surface of carbides of heavy metals with a large specific surface for catalytic reactions

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10002117A1 (en) * 2000-01-20 2001-08-16 Geesthacht Gkss Forschung Catalysis of the hydrogen sorption kinetics of hydrides by nitrides and carbides

Also Published As

Publication number Publication date
JPH11510427A (en) 1999-09-14
EP0824371A1 (en) 1998-02-25
BR9501693A (en) 1997-09-16
CA2219797A1 (en) 1996-11-14

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