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
  • B01J38/00—Regeneration or reactivation of catalysts, in general
  • B01J38/04—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst
  • B01J38/12—Treating with free oxygen-containing gas
• • 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
  • B01J23/44—Palladium
• • 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
  • B01J23/90—Regeneration or reactivation
  • B01J23/96—Regeneration or reactivation of catalysts comprising metals, oxides or hydroxides of the 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
  • 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
  • B01J27/224—Silicon carbide
• • 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
  • B01J38/00—Regeneration or reactivation of catalysts, in general
  • B01J38/02—Heat treatment
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B11/00—Obtaining noble metals
  • C22B11/02—Obtaining noble metals by dry processes
  • C22B11/021—Recovery of noble metals from waste materials
  • C22B11/026—Recovery of noble metals from waste materials from spent catalysts
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
  • C22B7/001—Dry processes
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
  • C22B7/009—General processes for recovering metals or metallic compounds from spent 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
  • B01J23/38—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

Definitions

• the present invention relates to a method for the decomposition of SiC or SiC-containing materials, in which the reaction is carried out exclusively via gaseous products in order to achieve as complete a reaction as possible.
• a preferred application is a recycling process for catalyst materials containing platinum metals on a silicon carbide (SiC) support material. The catalyst materials are freed from the support material in the thermal process.
• Catalysts are used for various reactions in technology in order to accelerate them or to make them possible in the first place. They are generally applied to a carrier material, usually in a thin layer, in order to increase the surface area that can be used for reactions and to simultaneously reduce the amount of expensive catalyst metal required. Furthermore, the mechanical strength of the catalyst increases with the application to a carrier material. In addition, the supported catalysts are easier to handle and apply in chemical reactors and can be protected against unwanted discharge. In the case of exhaust gas catalytic converters for internal combustion engines or systems, it is the support structures that make their use possible in the first place, since the channel structures produced with them, which are coated with the catalytic converter metal, allow the exhaust gas to flow through efficiently and make contact with the catalytic converter metal.
• Ceramic materials in particular have proven themselves as carrier materials, since they bring mechanical stability and inertness to the required reaction conditions.
• silicon carbide (SiC) is increasingly being used as a catalyst support material. Recycling these catalyst materials is interesting for several reasons.
• the applied catalytically active material is often an expensive or even very expensive metal due to its rarity or difficult production. Examples of this are in particular the frequently used platinum metals.
• Platinum metals also known as Platinum Group Metals (PGM) or Platinum Group Elements (PGE) are understood to mean the elements of groups 8 to 10 of the 5th and 6th periods. They include the precious metals ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum (Pt).
• Ru Platinum Group Metal
• Rh palladium
• Pr palladium
• Os osmium
• Ir iridium
• platinum platinum
• economically interesting by-products can also be obtained in addition to the recovered catalyst metals during work-up by skilful reaction control. For example, particularly pure silicon can be crystallized, which is used in the semiconductor industry. However, the quantities achieved so far are still very modest, so that recycling is primarily carried out under the aspect of recovering the catalyst metals.
• ceramic materials are predominantly used as carrier materials in exhaust gas catalytic converters for automobiles.
• Cordierite is commonly used in the catalytic converters for gasoline engines that have been installed since the early 1990s.
• This magnesium aluminosilicate ceramic can be melted very easily in electric high-temperature furnaces for recycling. The melt is run under reducing conditions. The ceramic is separated from the precious metals, which are bound in a so-called collector metal and obtained in high yields, with the release of oxygen.
• the carrier material of a diesel particulate filter (DPF) for diesel engines differs significantly from that for petrol engines.
• the carrier material usually consists of SiC. This material requires a significantly different melting process for recycling than cordierite.
• an oxidizing melt is carried out with the addition of oxygen in order to convert the carbon from the carbide into carbon dioxide. Only then is efficient precious metal recovery possible.
• the document DE 4305647 A1 describes a method for recovering valuable metals from used exhaust gas catalytic converters, which uses an opposite approach in that it is not the carrier material that is separated but the precious metals.
• the optionally comminuted catalyst material is mixed with an alkali metal chloride and heated in a rotary kiln in a chlorine gas atmosphere at temperatures of 350° C. to 700° C. for 0.2 h to 3 h. This results in direct conversion to the water-soluble hexachloro compounds of the platinum metals.
• the discharged reaction mass is then extracted with water and hydrochloric acid and the extract is further processed in the usual way.
• the support material of the catalyst is not changed in this process and can therefore even be reused. Only the valuable metals go into solution.
• the reaction temperatures are lower and no slag is produced.
• the document EP 0767243 B1 discloses a process for recovering active components from supported catalysts or unsupported catalysts by reaction with an essentially anhydrous hydrogen halide and optionally fractional separation.
• the catalyst material is reacted with essentially anhydrous hydrogen halide at 20° C. to 900° C. and a pressure of 0.01 bar to 10 bar in a tubular reactor, likewise while retaining the catalyst material in its original form.
• platinum and palladium for example, this takes place in the absence of oxygen.
• SiC is also mentioned as a suitable catalyst carrier material.
• normal pressure and 150.degree. C. to 700.degree. C. are used.
• the chlorides formed can either be discharged in gaseous form or they can also be dissolved with acids.
• the hydrogen halide gas is preferably diluted with an inert gas, preferably nitrogen.
• an inert gas preferably nitrogen.
• the object of the present invention was therefore to provide an improved method for decomposing SiC or SiC-containing materials which does not have the disadvantages of the prior art.
• the SiC support material should be separated from the platinum metals with as little residue as possible and the process should be as economical as possible.
• According to the invention is a method for the decomposition of SiC or SiC-containing materials, wherein the SiC or SiC-containing material and an additive in the form of one or more oxygen-containing compounds with the exception of oxygen are fed to a reactor under reduced pressure;
• the temperature and pressure in the reactor are adjusted so that the equilibrium oxygen partial pressure in the reactor
• the process conditions are selected in such a way that the formation of the passivating SiC>2 layer on the SiC or SiC-containing material is avoided and the silicon carbide is almost completely converted into the gas phase.
• the silicon carbide is oxidized by the oxygen-containing compound, whereby gaseous products are formed almost exclusively under the reaction conditions, which are quickly removed from the surface by the reduced pressure.
• the reaction can be controlled via the oxygen partial pressures of the reactants, which can be influenced by the temperature, the pressure and the oxygen partial pressure in the reactor.
• the equilibrium reaction of the oxygen-containing compounds to their reduced form and oxygen is thereby shifted to the side of oxygen release by setting a lower oxygen partial pressure in the reactor than in the oxygen-containing compound, which is done by selecting suitable pressures and temperatures in the reactor.
• the oxygen partial pressure in the reactor must also be lower than in the S1O2, which is formed from the SiC by oxidation with the oxygen released in this way, so that the equilibrium reaction of the SiO formed from the SiC in the first step with additional oxygen shifts to the S1O2 on the SiO side will. Further explanations on this can also be found below.
• SiC-based catalyst support materials in addition to the SiC, can also contain admixtures of S1O2, Al 2 O 3 or other oxides, which can also give off oxygen under the process conditions. This is also provided according to the invention.
• the oxygen partial pressure in the reactor is particularly preferably less than 10 13 hPa. It can, for example, be less than T10 14 hPa, less than 2-10 14 hPa, less than 3-10 14 hPa, less than 4-10 14 hPa, less than 5- 10 14 hPa, less than 6-10 14 hPa, less than 7-10 14 hPa, less than 8-10 14 hPa or less than 9-10 14 hPa.
• the oxygen partial pressure in the reactor is 10 16 hPa ⁇ p(0 2 ) ⁇ 10 13 hPa, 10 15 hPa ⁇ p(0 2 ) ⁇ 10 13 hPa or 10 14 hPa ⁇ p(0 2 ) ⁇ 10 13 hPa.
• the SiC-containing material comprises catalyst carrier materials.
• the SiC-containing material also includes platinum metals and the platinum metals are separated from the catalyst support materials.
• the platinum metals remain and accumulate. In a subsequent optional step, these can then be further cleaned, depending on the requirements, or separated from one another in the case of mixtures of platinum metals in the catalyst.
• the pressure in the reactor is preferably 0.001 hPa to 900 hPa, more preferably 0.01 hPa to 800 hPa, more preferably 0.02 hPa to 700 hPa, more preferably 0.03 hPa to 600 hPa, more preferably 0.04 hPa to 500 hPa, more preferably 0.05 hPa to 400 hPa, more preferably 0.06 hPa to 300 hPa, more preferably 0.07 hPa to 250 hPa, more preferably 0.08 hPa to 200 hPa, more preferably 0.09 hPa to 150 hPa, most preferably 0.1 hPa to 100 hPa.
• the pressure in the reactor can particularly preferably be at least 0.001 hPa, more preferably at least 0.01 hPa, more preferably at least 0.02 hPa, more preferably at least 0.03 hPa, more preferably at least 0.04 hPa, more preferably at least 0.05 hPa, more preferably at least 0.06 hPa, more preferably at least 0.07 hPa, more preferably at least 0.08 hPa, more preferably at least 0.09 hPa, most preferably at least 0.1 hPa.
• the pressure in the reactor can particularly preferably be at most 900 hPa, more preferably at most 800 hPa, more preferably at most 700 hPa, more preferably at most 600 hPa, more preferably at most 500 hPa, more preferably at most 400 hPa, more preferably at most 300 hPa, more preferably at most 250 hPa, more preferably at most 200 hPa, more preferably at most 150 hPa, most preferably at most 100 hPa.
• the equilibrium reaction of the silicon carbide with the oxygen-containing compounds can be specifically controlled by adjusting the pressure in the reactor.
• the temperature to which the SiC or SiC-containing material and the additive are heated can be from 1000° C. to 1650° C., preferably from 1100° C. to 1625° C., more preferably from 1200° C. to 1600° C. most preferably from 1300°C to 1600°C.
• the temperature can be particularly preferably at least 1100°C, more preferably at least 1150°C, more preferably at least 1200°C, more preferably at least 1250°C, most preferably at least 1300°C.
• the temperature can particularly preferably be at most 1625°C, most preferably at most 1600°C or 1550°C.
• the oxygen-containing compound is selected from the group consisting of CO2, H2O and a metal oxide or semimetal oxide. Metal oxides and semimetal oxides which can form gaseous suboxides under the reaction conditions are particularly preferred.
• the metal oxide or semimetal oxide has an equilibrium oxygen partial pressure of ⁇ 10 11 hPa between 1300° C. and 1700° C.
• it can be ⁇ 1-10-12 hPa, ⁇ 2-10 12 hPa, ⁇ 3-10 12 hPa, ⁇ 4-10 12 hPa, ⁇ 5-10 12 hPa, ⁇ 6-10 12 hPa,
• the equilibrium oxygen partial pressure is 10 14 hPa
• the metal oxide or semimetal oxide is preferably selected from the group consisting of SiO2 and Al2O3.
• the mass-related mixing ratio of SiC-containing material and metal oxide or semi-metal oxide can be between 2:1 and 1:2.
• reaction equations for the equilibrium reaction of silicon carbide with the oxygen-containing compounds are, for example, for S1O2 and Al2O3:
• the equilibrium can be shifted to the right side by reducing the pressure.
• Partial pressures can be realized in the reaction space.
• the conditions at the reaction front are designed in the process according to the invention in such a way that the oxygen partial pressure at this point is significantly lower than the equilibrium partial pressure of oxygen in the silicon dioxide corresponding to the respective reaction conditions. In this way, only gaseous reaction products (silicon monoxide, carbon monoxide) are formed, which escape from the reaction front and do not impede the progress of the reaction.
• Such a reaction procedure according to the invention can be used for all oxygen-containing compounds which form volatile suboxides or are gaseous.
• An example of a gaseous compound containing oxygen is CO2 according to the overall reaction equation below.
• FIG. 1 the partial pressure diagram of oxygen is plotted for various process conditions. It is assumed that the pressure in the reactor relates to the sum of the partial pressures of carbon monoxide, carbon dioxide, oxygen and silicon monoxide. The oxygen partial pressure for the two reactions is shown
• the SiC or SiC-containing material can be fed to the reactor in ground, crushed and/or untreated form.
• untreated refers to a mechanical comminution of the SiC or SiC-containing material that was not carried out and is therefore to be understood as a synonym for "not mechanically comminuted”. It is important to consider whether the additional surface area created by grinding or crushing into a powder or granulate and the resulting increased reaction rate justify the additional preparation step. With solid oxygen-containing compounds, grinding or crushing is particularly advantageous to allow mixing with them.
• the particle size can be, for example, in the range from 10 ⁇ m to 100 ⁇ m for a powder and in the range from 100 ⁇ m to 20 mm for a broken granulate.
• untreated SiC or material containing SiC can also be used without any problems. Furthermore, this also depends on the type of SiC or SiC-containing material. Large catalytic converters such as diesel particulate filters should tend to be crushed, while mostly small-scale catalytic converters for chemical plants can do without further crushing.
• the reaction is preferably carried out in a continuous reactor.
• a continuously operating reactor is particularly advantageous when using small-scale SiC or SiC-containing materials and solid oxygen-containing compounds, since a mixing and transport function can be easily integrated and the times for loading a batch system can thus be avoided.
• the larger diesel particle filters can also be processed in batches, for example in a vacuum oven, with gaseous oxygen-containing compounds.
• the reactor is preferably a rotary kiln, continuous furnace, fluidized bed reactor or a flat bed furnace.
• a push-through furnace is most preferably used as the continuous furnace. The latter is particularly suitable for the economical processing of uncomminuted catalysts in a continuous process.
• the reaction time in these reactor types is preferably between 0.25 hours and 10 hours. You can, for example, between 0.5 hours and 9.5 hours, between 0.75 hours and 9 hours, between 1 hour and 8.5 hours, between 1.5 hours and 8 hours, between 2 hours and 7.5 hours or be between 2.5 hours and 7 hours.
• the reaction time can be adjusted. With a high heat input into powdered material, as is possible with a fluidized bed reactor, short reaction times can be achieved. If, for example, an uncrushed diesel particle filter is selected as the starting material and is to be treated in a vacuum furnace, correspondingly longer reaction times are required.
• the heating takes place by thermal radiation, in particular from graphite, SiC or metallic heaters, or microwave radiation.
• thermal radiation in particular from graphite, SiC or metallic heaters, or microwave radiation.
• a further embodiment variant provides that the reactor is a plasma torch.
• the reaction time for this type of reactor is preferably between 0.1 second and 5 seconds. You can, for example, between 0.2 seconds and 4.5 seconds, between 0.3 seconds and 4 seconds, between 0.4 seconds and 3.5 seconds, between 0.5 seconds and 3 seconds, between 0.75 seconds and 2.5 seconds or between 1 second and 2 seconds. Due to the extremely high temperature in the plasma and the high heat input into the powdered material, extremely short reaction times can be achieved.
• a preferred embodiment variant provides that the heating takes place in a plasma burner, to which the SiC or SiC-containing material and the additive are fed, and the reaction takes place directly in the plasma flame.
• Plasma torches can also be operated at reduced pressure. A large amount of heat can be transferred easily and efficiently to the SiC or SiC-containing material via the generated plasma. This allows a high throughput with extremely short reaction times.
• the SiC or SiC-containing material and the additional material are to be provided in ground form as a powder so that they can be fed to the plasma torch together with the fuel gas. This procedure offers the advantage of a particularly small plant size.
• H2O can preferably also be used here as the oxygen-containing compound and fed to the plasma torch together with a hydrocarbon. To set the low oxygen partial pressures, the water/hydrogen equilibrium is then determined according to the reaction equation
• the mass loss of the SiC or material containing SiC can be at least 65%, preferably at least 70% or at least 75% or at least 80% or at least 85% or in particular at least 90%, based on the SiC proportion in design variants at most 99.5% or at most 99% or at most 98% or at most 97%.
• FIG. 1 shows the partial pressure diagram of oxygen for different process conditions.
• FIG. 2 shows the particle size distribution of the starting material containing SiC from Example 1.
• FIG. 3 shows the particle size distribution of the starting material containing SiC from Example 2.
• the particle size distributions of the ground materials were determined using a sieve analysis based on DIN 66165-2:2016-08 in a sieve tower from RETSCH, model AS200 control. It was worked without separating the fine fraction before sieving and with an amplitude of 0.7 mm/g, a sieving time of 20 min and an interval time of 1 s.
• the SiC-containing material for this example consisted of a catalyst material from a diesel particulate filter, which comprises a SiC-based carrier material and an active coating with the platinum metals platinum and palladium. It was comminuted in a sieve ball mill to give the particle size distribution shown in FIG. It was then mixed with DORSILIT sand (SiC>2 content 99.1% by weight) in a mass-related mixing ratio of 1:1 and placed in an AhOs crucible. The SiC content of the starting material was around 80% by weight (based on the catalyst material).
• a similar SiC-containing material from a catalyst material from a diesel particle filter as in example 1 was comminuted in a sieve ball mill to give the particle size distribution shown in FIG. It was then mixed with an Ar/C0 2 /H 2 mixture (approx.

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• 2021
  • 2021-07-23 DE DE102021119205.6A patent/DE102021119205A1/de active Pending
• 2022
  • 2022-07-08 JP JP2024503891A patent/JP2024527866A/ja active Pending
  • 2022-07-08 WO PCT/EP2022/069192 patent/WO2023001604A1/de not_active Ceased
  • 2022-07-08 US US18/579,958 patent/US20240351016A1/en active Pending
  • 2022-07-08 EP EP22750679.7A patent/EP4373980A1/de active Pending
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