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
  • 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
  • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
• • 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
  • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
  • B01J23/46—Ruthenium, rhodium, osmium or iridium
  • B01J23/464—Rhodium
• • 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
  • B01J23/64—Platinum group metals with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/652—Chromium, molybdenum or tungsten
• • 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
  • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
  • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
• • 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
  • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
• • 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
  • 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
  • B01J35/58—Fabrics or filaments
• • 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
  • 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
  • B01J35/61—Surface area
  • B01J35/617—500-1000 m2/g
• • 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
  • B01J37/08—Heat treatment
• • 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
  • B01J37/28—Phosphorising
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/06—Metallic powder characterised by the shape of the particles
  • B22F1/062—Fibrous particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/002—Manufacture of articles essentially made from metallic fibres
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/02—Making metallic powder or suspensions thereof using physical processes
  • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B21/00—Nitrogen; Compounds thereof
  • C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
  • C01B21/24—Nitric oxide (NO)
  • C01B21/26—Preparation by catalytic or non-catalytic oxidation of ammonia
  • C01B21/265—Preparation by catalytic or non-catalytic oxidation of ammonia characterised by the catalyst
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
  • C01C3/00—Cyanogen; Compounds thereof
  • C01C3/02—Preparation, separation or purification of hydrogen cyanide
  • C01C3/0208—Preparation in gaseous phase
  • C01C3/0212—Preparation in gaseous phase from hydrocarbons and ammonia in the presence of oxygen, e.g. the Andrussow-process
  • C01C3/0216—Preparation in gaseous phase from hydrocarbons and ammonia in the presence of oxygen, e.g. the Andrussow-process characterised by the catalyst used
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C5/00—Alloys based on noble metals
  • C22C5/04—Alloys based on a platinum group metal
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
  • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
  • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
  • F01N3/28—Construction of catalytic reactors
  • F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
  • F01N3/2807—Metal other than sintered metal
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
  • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
  • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
  • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
  • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
  • F01N3/28—Construction of catalytic reactors
  • F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
  • F01N3/2835—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support fibrous

Definitions

• the present invention relates to catalyst structures for the production of nitric acid and hydrocyanic acid and to the production of catalysts suitable metal fibers based on precious metals, nets and webs produced therefrom and to processes for producing such fibers, nonwovens and nets.
• DE 199 45 742 C1 discloses a metal fiber catalyst body whose metal fibers are produced by melt extraction. From the fibers, using textile techniques i.a. Fiber fleece created. The catalyst material platinum, palladium rhodium is contained in the fibers or present as additional fibers in the fabric.
• DE 100 00 097 A1 discloses melt extraction processes for the production of metal fibers from thin fibers with diameters of less than 100 ⁇ m with melt bath temperatures of more than 1500 ° C.
• the object of the present invention is to produce fibers, nets or fleeces based on precious metals.
• the procedure should be as simple as possible.
• the catalysts are designed to maintain high efficiency in the long term.
• the melting point of a metal before fiber processing by means of boron or phosphorus is drastically reduced and the boron or phosphorus after the production of fibers or nonwovens or nets made of fibers largely removed again.
• the melting point of a precious metal-based metal in particular based on the platinum group metals platinum, palladium, rhodium, ruthenium and iridium and optionally additional alloying elements of up to 30 wt .-% of the metals nickel, cobalt, gold, rhenium, molybdenum and tungsten lowered significantly by boron or phosphorus, in particular by at least 400 0 C, preferably by at least 500 0 C.
• boron or phosphorus in particular by at least 400 0 C, preferably by at least 500 0 C.
• Phosphorus generated Such eutectic mixtures are generally between 1 to 5 wt .-% boron or phosphorus based on the metal to be processed.
• the present invention is also still feasible outside the eutectic mixtures. Below 0.5% by weight of boron or phosphorus, however, the effect becomes unusable because the wide melting interval of the alloy leads to considerable segregation. If the proportion of boron or phosphorus is too high, on the one hand boron or phosphorus is unnecessarily burned, which leads to the increased consumption as a further disadvantage that the expense of removing these elements likewise increases unnecessarily.
• the lowering of the melting point according to the invention is particularly pronounced with platinum, iridium and their alloys.
• the use of boron to lower the melting point is preferred, since with the use of phosphorus generally higher safety precautions must be taken.
• fibers with a diameter between 10 and 200 .mu.m, in particular between 50 and 100 microns are available.
• the drawing of fibers from the melt, in particular by means of melt extraction according to the invention by lowering the melting temperature by means of boron or phosphor energy-saving and device conserving in particular compared to the effort without melting point reduction or compared to the cost of producing
• the fibers can also be produced in a wire casting process according to DE 197 57 093 A1 or in a melt spinning process according to DE 31 36 303 A1.
• nonwovens or nets are largely removed again.
• the oxidation of the boron or phosphorus is not carried out under an air atmosphere, but milder conditions such.
• the melting point of 1770 0 C can be reduced to 790 0 C. This facilitates the production of Pt alloy fibers, eg PtRh ⁇ , by the melt extraction process.
• the melting point of Pd is reduced in a similar manner by alloying of about 3 wt .-% B of 1555 ° C at 1065 0 C.
• the boron-alloyed PtRh5 fibers are at a temperature (eg. B. 750 0 C) presintered just below the eutectic. During presintering, the boron oxidizes and, for the most part, the resulting boron oxide liquefies or vaporizes. Also, first sintered connections are created between the fibers. By a short-term (a few minutes) sintering treatment at a temperature in the range 1200 ° C-1400 ° C (eg with the flame), the nonwoven sinters firmly together. Any remaining boric oxide traces can be removed by rinsing in warm water.
• a temperature eg. B. 750 0 C
• nonwovens can be produced from palladium alloys.
• the eutectic of the Pd-B system is significantly higher at 1065 ° C and the melting point of the Pd at 1555 ° C is significantly lower than platinum, greater care is required in setting the temperatures for pre-sintering and sintering.
• the suitable temperatures can be easily determined by simple aging experiments and subsequent metallographic ground investigations.
• the prepared ingots of the B-containing PtRh5 alloy were melted in a zirconium oxide crucible in a melt extraction device (see description in DE 199 45 742 C1, column 2, from line 40) under an argon protective gas atmosphere, wherein the temperature of the molten bath in the range 820-860 0 C was held.
• the fibers were scattered on a flat base made of aluminum oxide with dimensions of 400 mm ⁇ 800 mm until the basis weight of the fibers reached 1500 g / m 2 .
• the thus-laid nonwoven fabric was placed on the support in a chamber furnace under air atmosphere, heated to 750 0 C and held at this temperature for 5 hours.
• the boron diffused from the fibers, oxidized on the surface of PtRh alloy and formed boron oxide, which is liquid at this temperature (melting point 450 0 C).
• the pre-sintered fleece backing was removed from the oven and cooled to room temperature. Upon cooling, the boron oxide was allowed to dissolve in warm water causing the web to dislodge from the pad. Due to the presintering, sufficient mechanical strength had already been created to suspend the nonwoven with platinum wires. At this stage, however, the fleece was still very fragile and had to be handled with great care.
• the web was heated to white heat (estimated at about 1200 0 C) and held for 2-3 minutes. After this treatment, the strength had increased significantly. The strength was determined by firmly tensioning a nonwoven blank (diameter 95 mm) around the circumference and pressing in a steel hemisphere (diameter 40 mm) until the nonwoven was torn. The maximum force reached was measured at 95 N. In comparison, 2 nonwovens made by drawing and sintering drawn PtRh5 wires and also having a basis weight of 1500 g / mm 2 were tested. The first nonwoven was oven sintered at 1640 ° C. for 10 minutes and had a compressive strength of 10 N.
• the second nonwoven fabric was sintered at 1350 ° C. for 12 hours and had a compressive strength of 85 N.
• the nonwoven according to the invention could be handled without difficulty.
• the boron content of the PtRh5 alloy had depleted to ⁇ 0.001%.
• the nonwoven had a porosity of 91%.
• the pressure losses of the nonwovens were by a factor of 1.4 higher than in the nets and the concentrations of nitrous oxide in the product gas in the nonwovens and nets were comparable.
• the oxidation efficiency of the webs was 96.2% under the conditions tested and remained at that level throughout the test time of 126.0 hours.
• the oxidation efficiency of the nets was 96.0% at the beginning of the test and dropped to 95.5% during the test period.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Toxicology (AREA)
• Health & Medical Sciences (AREA)
• Combustion & Propulsion (AREA)
• Inorganic Chemistry (AREA)
• General Engineering & Computer Science (AREA)
• Nanotechnology (AREA)
• Metallurgy (AREA)
• General Health & Medical Sciences (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Catalysts (AREA)
• Inorganic Fibers (AREA)
• Nonwoven Fabrics (AREA)
• Powder Metallurgy (AREA)

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• 2008
  • 2008-08-12 DE DE102008038611.1A patent/DE102008038611B4/de not_active Expired - Fee Related
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