US20070089807A1 - Method for spreading noble metal on iron particle surface - Google Patents

Method for spreading noble metal on iron particle surface Download PDF

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Publication number
US20070089807A1
US20070089807A1 US11/584,669 US58466906A US2007089807A1 US 20070089807 A1 US20070089807 A1 US 20070089807A1 US 58466906 A US58466906 A US 58466906A US 2007089807 A1 US2007089807 A1 US 2007089807A1
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Prior art keywords
iron particles
iron
degrees centigrade
particles
noble
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Abandoned
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US11/584,669
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English (en)
Inventor
Ya-Hsuan Liou
Shang-Lien Lo
Chin-Jung Lin
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Individual
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Individual
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/80—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/54—Contact plating, i.e. electroless electrochemical plating

Definitions

  • the present invention relates to method for distributing noble metal on the surface of iron particles uniformly, and especially to a method for treating the surface of iron particles and evening the activity of the surface of the iron particles.
  • Zero-valent iron Fe 0
  • water pollutants such as organic matter with chlorine, pesticides, stains, nitrates or radiation matter under natural conditions.
  • a reaction (1) has organic matter with chlorine which acts as an oxidizing agent: Fe 0 +Org-Cl+H + ⁇ Fe 2+ +Org-H+Cl ⁇ (1)
  • zero-valent iron (Fe 0 ) can convert organic matter with chlorine, which may be carcinogenic, into a non-toxic hydrocarbon. Therefore, the applications of the zero-valent iron (Fe 0 ) are becoming more common and diverse due to their low cost and low-end technology level.
  • a small quantity of noble metals can be coated on the surface of the zero-valent iron (Fe 0 ), such as palladium (Pd), platinum (Pt) or copper (Cu), to increase surface activity.
  • the noble: metal increases the reaction rate of redox and degrades the pollutants.
  • the reaction rate has been proven to be tens times than that of the zero-valent iron (Fe 0 ). Because of the potential difference between the zero-valent iron (Fe 0 ) and the respective noble metal, the zero-valent iron (Fe 0 ) is driven to release electrons to the surface of the noble metal.
  • Hydrogen ions absorb the electrons and become hydrogen atoms with high reduction capacity. The hydrogen atoms can degrade the pollutants or combine with another hydrogen atom to form hydrogen gas.
  • M N represents a respective noble metal
  • M N H ads represents a hydrogen atom attached to the surface of the noble metal.
  • a total reaction can be taken as a catalytic reaction for the noble metal catalyzing the zero-valent iron (Fe 0 ) and as a corrosion reaction of the organic matter with chlorine.
  • the zero-valent iron (Fe 0 ) can be immersed in a solution with noble-metal ions and the noble-metal ions can be reduction to zero valence via the high active of the zero-valent iron (Fe 0 ), so that the zero-valent iron (Fe 0 ) is more highly active than the noble-metal ions.
  • the noble-metal ions can accept electrons to become noble-metal atoms attached to the surface of the zero-valent iron (Fe 0 ), such as the reaction (6) as shown below: n/2 Fe 0 +M N n+ n/2 Fe 2+ +M N (6)
  • commercial iron that has not received the appropriate pre-treatment, has a passive oxide layer formed its surface, for example, Fe 3 O 4 , ⁇ -Fe 2 O 3 , or the like.
  • the passive oxide layer is formed due to the high temperature of the process or as a natural consequence of long-term storage.
  • the zero-valent iron Fe 0 ) with the passive oxide layer signifies uneven surface activity, and that means the replacement of noble metal will occur at some areas while at some other areas no replacement will occur at all.
  • large-sized particles of noble metal are provided and the surface area is correspondingly small, so the catalysis efficiency decreases.
  • a method for spreading noble metal on an iron particle surface according to the present invention is provided to activate the surface of iron and react the iron particles with noble-metal ions, so that the uniformity and the activity of the noble metal attached to the iron surface can be both improved.
  • a method for spreading noble metal on the iron particle surface includes: providing a plurality of iron particles, cleaning-the iron particles up and separating the iron particles from cleaning water, drying the iron, particles, placing the iron particles into a heater oven integrated with a reaction gas, heating the iron particles to reduce oxidation, placing the iron articles to a noble-metal-ion solution for immersion plating, processing the iron particles with a solid-and-liquid separation, and drying the iron particles.
  • the heating temperature of the heating oven ranges from 300 to 500 degrees centigrade and has a duration that ranges from 3 to 5 hours.
  • the iron particles are first activated in order to react with the noble metal so that the activity and the uniformity of the noble metal attached to the iron surface are improved.
  • FIG. 1 is a flow chart of a method for spreading noble metal on the iron particle surface according to the present invention
  • FIG. 2 is a SEM image of untreated commercial iron scanned by a scanning electron microscope (SEM in short);
  • FIG. 3 is a SEM image of commercial iron distributed with noble metal according to the present invention and scanned by a SEM;
  • FIG. 4 is a diagram of commercial iron distributed with noble metal according to the present invention compared to untreated commercial iron reacting with a nitrate.
  • a method for spreading noble metal on the iron particle surface according to the present invention is provided.
  • a reaction gas that includes hydrogen, mixes with nitrogen in a ratio of about 1:4. This process takes place under a heating temperature ranging from 300 to 500 degrees centigrade and a duration ranging from 3 to 5 hours for the reduction in order to reduce a passive oxide layer formed on a surface of zero-valent iron (Fe 0 ) particles.
  • a noble metal represented by a characteristic w
  • an embodiment of the method according to the present invention prepares 0.5% Cu/Fe (w/Fe 0 ; w represents Cu), and includes:
  • the heater oven provides a heating profile that increases the temperature from room temperature to about 150 degrees centigrade (150° C.) at a rate of about 10 degrees centigrade per minute (10° C./min), and then remaining for about 30 minutes at about 150 degrees centigrade (150° C.) in order to remove all moisture.
  • the oven's temperature begins increasing to about 400 degrees centigrade (400° C.) at a rate of about 10 degrees centigrade per minute (10° C./min), remaining at 400 degrees centigrade (400° C.) for about 3 hours, and then returning back to room temperature.
  • the pure nitrogen gas cleans the iron particles via the flow rate of about 250 milliliters per minute (250 mL/min) for about 15 minutes (15 mins). After that, the iron particles can be removed from the heating oven (S 108 ).
  • the reduced iron articles are, then placed in a 250 mL solution of noble-metal-ion (containing a Cu-ion concentration of 100 mg/L) for immersion plating. The solution is then stirred slowly for 5 minutes (5 mins) (S 110 ). The iron particles are immersed in the noble-metal-ion solution and the noble metal particles are formed and attach to the surface of the iron surface easily because the noble metal ions accept electrons easier than the zero-valent iron (Fe 0 ).
  • the iron particles are then removed from the liquid via solid-and-liquid separation after the plating step via a high-speed centrifugal dewaterer. This step lasts at least 5 minutes at a rotation speed of about 5000 rpm.
  • the iron particles are then dried by the freeze dryer as soon as possible for at least 12 hours at about ⁇ 55 degrees centigrade and 0.2 Torr.
  • highly active dual metal 0.5% Cu/Fe (w/Fe 0 ) particles (powders) are thereby manufactured (S 114 ).
  • Another noble metal such as Pd or Pt can be applied to the mentioned steps in the method to manufacture the dual metal, such as Pd/Fe (w/Fe 0 ) or Pt/Fe (w/Fe 0 ).
  • SEM images of conventional 0.5% Cu/Fe and the 0.5% Cu/Fe of the present invention caught by a scanning electronic microscope (SEM in short) are provided.
  • the distinguish point between the two images is the particle size of the copper element attached to the iron element.
  • the energy-dispersing X-ray (EDX in short) is applied to distinguish if any copper element exists from the distinguish point, and the size of most of the copper particles can be measured by the scale bar in SEM range from 750 and 850 nanometers (nm).
  • the size of most of the copper particles manufactured via the method of the present invention are about 150 nanometers (nm). Therefore, as the images show, the particle size of the dual metal according to the present invention is really small.
  • identified characters A, B and C represent three iron particles respectively, and only the particle of A can be platted the copper (Cu) which the size is around 750-850 mm, the particles of B and C can not be platted the copper due to the oxidation layers of the particles of are too thick in FIG. 2 , but this phenomenon does not exist in FIG. 3 .
  • This proof shows that the distribution uniformity of the copper particles of the dual metal in FIG. 3 is much more than that in FIG. 2 .
  • the principle and operation of SEM or EDX is common knowledge and needn't further description.
  • the dual metal according to the present invention with high activity reduces the catalysis time due to the increased effective surface area.

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  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Electrochemistry (AREA)
  • Powder Metallurgy (AREA)
  • Catalysts (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
US11/584,669 2005-10-25 2006-10-23 Method for spreading noble metal on iron particle surface Abandoned US20070089807A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
TW094137349A TW200716281A (en) 2005-10-25 2005-10-25 Fabricating method of uniformly dispersing noble metal on surface of iron particle
TW94137349 2005-10-25

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US20070089807A1 true US20070089807A1 (en) 2007-04-26

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US (1) US20070089807A1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
TW (1) TW200716281A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2990267A (en) * 1959-06-26 1961-06-27 Dow Chemical Co Preparation of metal powders
US3476530A (en) * 1966-06-10 1969-11-04 Chomerics Inc Iron based conductive filler for plastics
US4833040A (en) * 1987-04-20 1989-05-23 Trw Inc. Oxidation resistant fine metal powder
US20030059604A1 (en) * 2001-09-05 2003-03-27 Fuji Photo Film Co., Ltd. Material coated with dispersion of ferromagnetic nanoparticles, and magnetic recording medium using the material
US20040092608A1 (en) * 2002-08-09 2004-05-13 Dennis Stamires Method for performing a fischer-tropsch process using an iron-containing layered material

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2990267A (en) * 1959-06-26 1961-06-27 Dow Chemical Co Preparation of metal powders
US3476530A (en) * 1966-06-10 1969-11-04 Chomerics Inc Iron based conductive filler for plastics
US4833040A (en) * 1987-04-20 1989-05-23 Trw Inc. Oxidation resistant fine metal powder
US20030059604A1 (en) * 2001-09-05 2003-03-27 Fuji Photo Film Co., Ltd. Material coated with dispersion of ferromagnetic nanoparticles, and magnetic recording medium using the material
US20040092608A1 (en) * 2002-08-09 2004-05-13 Dennis Stamires Method for performing a fischer-tropsch process using an iron-containing layered material

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TW200716281A (en) 2007-05-01
TWI296947B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 2008-05-21

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