CA2026554A1 - Electrocatalyst for the oxidation of methane and an electrocatalytic process - Google Patents
Electrocatalyst for the oxidation of methane and an electrocatalytic processInfo
- Publication number
- CA2026554A1 CA2026554A1 CA002026554A CA2026554A CA2026554A1 CA 2026554 A1 CA2026554 A1 CA 2026554A1 CA 002026554 A CA002026554 A CA 002026554A CA 2026554 A CA2026554 A CA 2026554A CA 2026554 A1 CA2026554 A1 CA 2026554A1
- Authority
- CA
- Canada
- Prior art keywords
- group
- process according
- electrocatalytic process
- mixtures
- conducting
- 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.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
- C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
- C25B11/081—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound the element being a noble metal
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
- C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
- C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
- C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
- C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
- C25B11/095—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds at least one of the compounds being organic
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B3/00—Electrolytic production of organic compounds
- C25B3/20—Processes
- C25B3/23—Oxidation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
- H01M4/90—Selection of catalytic material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/08—Fuel cells with aqueous electrolytes
-
- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Catalysts (AREA)
- Electrodes For Compound Or Non-Metal Manufacture (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An electrocatalytic process for the partial oxidation of methane employs an electrocatalyst in the form of a deposit catalyst comprising an electrode having a conducting catalyst layer deposited thereon.
The catalyst comprises an element selected from the group consisting of Group IB metals, Group VIB metals, Group VIII metals and mixtures thereof.
An electrocatalytic process for the partial oxidation of methane employs an electrocatalyst in the form of a deposit catalyst comprising an electrode having a conducting catalyst layer deposited thereon.
The catalyst comprises an element selected from the group consisting of Group IB metals, Group VIB metals, Group VIII metals and mixtures thereof.
Description
` - 2 ~ 3 ~ ~:
,` ` ~, , BACKGROUND OF THE INVENTION
The present invention is drawn to an ;mproved electrocatalyst and an improved electrocatalytic process and, more particularly, a composite electrocatalyst for use in the partial o~idation of methane by an electrocatalytic process. .
Methane, the principal component of natural ~as, is -~
available in large quantities in ~ellhead gas and other `~
by-products of petroleum recovery and coal mininq `-processes. One of the major businesses of many refineries and chemical plants is to upgrade low value ~-hydrocarbons such as methane into more valuable products. Typical ~ethane conversion ~roceææes known in `
the prior art are disclosed in U.S. Patents 4,205,194, ``
4,499,322 and 4,523,049. These processes rely on contacting thc methane with a catalyst reagent in the presence of oxygen to produce a higher hydrocarbon product. These processes uffer from a number of --~
drawbacks including low conversion rates, great catalyst ~` 20 instability, exce~sive formation of unde~irable carbon oxides and the like.
. Naturally, it would be highly desirable to develop a stable cataly~t useful in the oxidation of methane and -~`
a method for the oxidation of methane which exhibi~s excellent conversion rates without excessive formation of deleterious carbon oxides. ~
~.
,` ` ~, , BACKGROUND OF THE INVENTION
The present invention is drawn to an ;mproved electrocatalyst and an improved electrocatalytic process and, more particularly, a composite electrocatalyst for use in the partial o~idation of methane by an electrocatalytic process. .
Methane, the principal component of natural ~as, is -~
available in large quantities in ~ellhead gas and other `~
by-products of petroleum recovery and coal mininq `-processes. One of the major businesses of many refineries and chemical plants is to upgrade low value ~-hydrocarbons such as methane into more valuable products. Typical ~ethane conversion ~roceææes known in `
the prior art are disclosed in U.S. Patents 4,205,194, ``
4,499,322 and 4,523,049. These processes rely on contacting thc methane with a catalyst reagent in the presence of oxygen to produce a higher hydrocarbon product. These processes uffer from a number of --~
drawbacks including low conversion rates, great catalyst ~` 20 instability, exce~sive formation of unde~irable carbon oxides and the like.
. Naturally, it would be highly desirable to develop a stable cataly~t useful in the oxidation of methane and -~`
a method for the oxidation of methane which exhibi~s excellent conversion rates without excessive formation of deleterious carbon oxides. ~
~.
2~5~
: 89-328 :1 Accordingly, it is a principal object of the 3 present invention to provide an i.mprovea - electrocatalytic process for the parti.al oxidation of a methane containing gas.
It is a particular object of the present invention , -to provide an improved e.lectxocatalyst for use in the electrocatalytic process as set forth above. ~;.
! It is a ~till fuxther object of the present invention to provide an improved electrocatalyst .~.`
comprising a composite electrocatalyst comprising a ...
s electrode having a finely dispersed conducti.ng catalyst .-:
disposed thereon.
Further objects and advantages of the present -invention will appear hexeinbelow. -.,':,..'~
SUMN~RY OP THE INVENTION
The present invention is drawn to an improved ,~
electrocataly~t and an improved electrocata.lytic process .;;-~
for converting methane to higher value hydrocarbons by ... ;~
the partial oxidation thereof.
The electrocatalyst of the present invention comprises a composite electrocataly t consisting o~ an .
electrode having a finely di.spersed conducting ca~alyst ~.
layer deposited thereon. The electrode compxises a material selected from the group consisting of metal.s, '',.
-3~
~`- 2 ~ 2 ~
j 89-328 ~etal alloys, non-metal conducting materials and mixture~ thereof. In accordance with the present invention, the metals and meta~ alloys used in forming the electrode of the composite electrocatalyst contain ,Aj 5 an element selected from the group consisting of Group .:~-IB metals, Group VIB metals, Group VIII metals and `-mixtures thereof. Suitable non-metal conducting --;
materials for forming the electrode of the --¦ electrocatalyst of the present invention are selectedfrom the group consisting of carbon derived materials, ceramics, polymers, metal oxides and mixtures thereof.
The finely dispersed conducting catalyst deposited on the electrode compri~es an element selected from the group consi~ting of Group IB metals, Group VIB metals, Group VIII metals and mixtures thereof. The material ~
from which the electrode is made may be in the orm of a , rod, grid, plate or felt material. In a preferred embodiment of the present invention, the electrode is covered with ~ layer of a conducting polymer and the finely dispersed aonducting catalyst is deposited on t~e conducting polymer. Suitable materials from which the conducting polymer is formed include teflon, ¦~ polyaniline, polypirrol, per~luorinate~ membranes, polymeric fluorocarbon copolymer, acrylic polymers, metacrylic polymers and mixtures thereof.
, ,~,', . ,~:' " . ~ , ,j j ,, .,, , . ., , . ,. ~ ,. , ~;. " ,, ,,~ ,......... ..
2~26~
8~-328 , ~
The process of the present invention comprises an i electrocatalytic process for partial oxidation of a ~; methane containing gas which aavantageously combines the advantages of both an electr,Dlytic process and cata]ytic -~
process for converting methane to a higher value hydrocarbon. The electrolytic process comprises ~;
preparing the composite electrocatalyst of the present.-invention as set orth above and thereater contacting a methane containing gas with the composite electrocatalyst in an electrolytic cell under ~-electrochemical conditions so as to partially oxidize the methane.
The process of the present invention employing the electrocatalyst of the present invention offers an efficient and economical mechanism~for converting methane to more valuable hydrocarbon products.
DETAILED~DESCRIPTION
The present invention i6 drawn to an improved electrocataly t and an improved electrocatalytic~pxocess and, more particularly, a compo~ite electrocatalyst for use in the partial oxidation of methane by an elec~rolytic proces In accordance with the process of the present invention, methane is oxidized in an electrolytlc cell ::~ :,;
i, ~ . :.,.~.
7 ~ ~
-- 2~26~4 ` .~,., , having an anode, a cathode and an electrolyte solution media. In accordance with the present invention, the ~ -anode i~ in the for~ of the electrocatalyst of the ,`
present invention, the details of which will be set --forth hereinbelow. The electrochemical proces3 of the -- `
invention results in the partial oxidation of ~ethane forming a methane containing gas to yield oxigenated hydrocarbon of light molecular weight under moderate proces3ing conditions. -~
The proce~s of the present invention employs a ~-~tandard electrolytic cell. In the ca~e of a compact electrocatalyst, that is where the~finely di~per~ed catalyst material i8 depo~ited on a non-porous -`
electrode, the procedure involves the reactant gas, in thig case a methane ~ontaining gas, diffusing towards the electrocatalyst of the present invention throug~ an electrolytic solution in which a cathode is al80 immer~ed. Where a porous electrocatalyat iB employed, ~ ~
that i8 where the catalyst io in the form of a finely ~;
di3per~ed pQrticle deposited on a porous electrode, i.e. ~`
felt material, grid or the like, the reactant gas would preferably diffuse through the porous electrod~ in order to avoid gas ~olubility and diffusion limitations. The foregoing are typical of standard electrolytic ~-~
operations.
~ ' ' ."~'' , -6- ~
~.... , , ... . , , , . . .. ~ -;
202~4 The reactant gases used in the proce~s of the present invention comprise p1are methane, met~ane diluted in hydrogen and an alternating pulse of methane and hydrogen. During the electrolytic operation, when pure methane i~ employed as the reactant gas, the methane ~-`
constantly flows towards or through the electrocatalyst. When diluted methane i8 u~ed as a reactant ga~, the methane flows towards or through the electrocatalyst in a constant or pulsed manner with ~
~1 10 hydrogen or alternately with hydrogen and methane. By ' ~.~'~!''.' loading the eloctrocatalyst with hydrogen, the catalytic activity is improved. ~`~
The electrolytic solution used in the process of ; the present invention may be an acid, a basic or a ~; 15 neutral pH solution. Typical acid solutions include sulphuric acid, perchloric acid and ~he likeO Typical base solutions includo sodium hydroxide, ammonium hydroxide and the 11ke. In addition, ionic 3alt~ ~ight be used as the electrolytic ~olution. Such salts include pota~sium nitrate, sodium nulfate and tho like.
In addition, ionic mediator~ such a~ Fe(III), Cr~
Co(III), Ce(IV) or Cd(II) ~ight also be used in solution.
;~ As noted~above, the anode emp]oyed in the process of the prenent invention i8 in the form of an electxocatalyst in accordance with the present _ i3' ` 2~2~5~
~ 89-328 "''" ' ".
invention. The electrocatalyst i8 a composite electrocatalyst comprising an electrode having a finely ;~
dispersed electronically conductive catalyst deposited thereon. The catalyst may bc~ deposited in any known manner depending on it~ form ~uch a~ by painting, electronically deposited, etc. The electrode can be in the form of a compact or porous material such as, or example, a rod, a plate, a grid or felt material. The ~-,.
material from which the electrode i8 formed is selected ; 10 from the group of materials consisting of metals, metal l alloys, non-metal conducting materials and mixtures thereof. The metals and ~etal alloys whic~ form the electrode of the composite electrode catalyst contain an element selected from the group consisting of Group IB
metals, Group VIB metals, Group VIII metals and mi~tures thereof. Particularly suitable materials contain an ~1 element selectea fro~ the group consisting of Au, ~e, Ag, Pt, Ir, Rh, Pd, Steel, Mo, Ni and mi~tures thereof.
The most preferred materials from which the electrode i~
3i 20 formed contain an ele~ent ~elected from the group con~isting of Ag, Fe, Steel, ~i and mixtures thereof. ~
In the event the electrode i8 formed from a non-metal ~;
conducting material, the non-metal conducting materials most suitable are selected from the group consi~ting of i 25 carbon derived materials, ceramics, polymers, metal oxides and mixtures thereof. ~ -~
~" ,',, ~; ' ". ' " ' ' ' ' : , ' , ~?;- ~
,~ ;, .. ~ .
2~26~5~ ~ ~
, ', . -~ .
The catalyst deposited on the electrode is a fin~ly disper~ed conducting materia]L which contains an element selected from the group consiRting of Group IB metals, Group VIB metals, Group VIII metals and mi~tures d 5 thereof. The cataly~t material iR finely dispersed on the electrode in known manner a~ i8 commonly practiced a~ descxibed above.
It has been found that the smaller the particle --si~e of the finely dispersed cataly~t material, the better the catalytic activity a~sociated with the electrocatalyst. The particle size of the material particle di~persed on the electrode i9 about between ~
0.0001 pm to about 800 ~m and preferably from about `-`
0.001Jum to about 200 ~m. The thickness of the finely ~ -~
lS aisper~ed conducting catalyst layer shoula be a~ uniform -as possiblo in order to provide effective activity. The thickness requirements of the dspersed conducting catalyst layer are balanced 80 aB ~0. in~ure structural integrity while at the same time employing an economic amount of catalyst material. It has been found that catalyst layers of 0.01 ~m exhibit the necessary ; structural integrity and, generally, thicknesse~ o~
¦ ~ greater than 2 ~m are undesirable for economic reasons.
In a preferred embodiment of the electrocatalyst of the present invention, a conducting polymer layer i~
, , `,~`,.. '.
. .,~
~S
2 0 2 ~
l 89-328 .' .-, deposited on the electrode and the fin~ly disper~ed catalyst ~aterial is deposited on the conducting polymer ~-material. The presence of the conducting polymer improves the dispersion of the finely ~eposited cataly~t on the electrode thereby requiring u~e of less catalyst --material. Suitable conducting polymer material~ are 3 selected from the group consi~ting of teflon, ~ polyaniline, polypirrol, perfluorinated membrane~, '1 : , ~ polymeric fluorocarbon copol~mer, acrylic poly~er~, ~
~s ~1 10 metacrylic polymers and mixtures thereof and the mo~t ¦~ ~ preferred materials are gelected from the group consigting of poIypirrol and perfluorinated polymer~ and mixtures thereof. The thicknes of the conducting polymer layers ghould not exceed 5.0 ym and, preferably ghould not exceed l.0 ~m in order to avoid unreasonable electrical resistance.
The electrolytic cell ~ay be operated in the mode -;
of a fuel cell by the reduction of o~ygen at the cathode 80 as to produce ~2 When the cell i8 operated in this mode, no electrical current need be applied. The -~
chemical products obtained when operating the electroche~ical cell as a fuel cell are similar to those --obtained when operating the electrolytic cell under the process conditions set forth below. The advantage of `--operating the electrochemical cell as a fuel cell i~ -. ' ' -10- ' 2 0 2 ~ 3~i 4 that no electrical cu~rent need be applied. This operation is exemplified hereinbelow in Example IV. ;~
As noted above, the proce~s of the present invention combine~ ele~trolytic proce~ing t~chnology and catalytic proce-~sing technology for converting methane to a higher oxidized product. The electrocatalytic process of the pre~ent invention is conducted under the following operating parameter~
Temperature: 0 - 200C, preferably 20 to 70C; ~;~
Pressure : 0.5 - lO0 atm., preferably 0.8 to 30 atms. ,.,.`
Voltage : 0 to 20 volts applied either constant, alternating or pulses; and Current : 0 to l.0 amps cm 2, preferably 0 to 0.5 amps cm 2 applied either ;~
constant, alternating or pul~ed.
,~
By loading the electrocatalyst with hydrogen, that i8, ~eeding hydrogen to the electrocataly~t with methane pulsing alternating with methane and hydrogen, the conver~ion of methane per gram of catalys~ i3 i~proved, : .
i.e., catalyst activity. A~ noted above, ~ethane may be fed to the electrocatalyst either with hydrogen or alternating pul~ed ~ith hydrogen and methane.
' . .'`,~
-11- . .'. ."
.! ~ 2 ~ 2 ~ ~ 5 4 .
`, , .
In addition, the cathode of the electrochemical cell may take the form of th~e compo~ite electrocata],yst described above. In t~i~ ca~e, the anode and cathode may be selectively alternated during the electrolytic process thereby extending the life of the elements.
The inve~tion will be fur~her illustrated by the following example~ which are in no way int0nded to be ', L . limiting. ~' EXAMPLE I
Example I wa~ run in order ~o demonstrate that;~'.
known catalysts used in the oxidation of methane are ~.`
ineffective when employed in the electrocatalytic ~ , proce-cs in accordance with the present invention. The electrochemical cell employed in the e~amples is of~p lS known construction and con~ist~ of (1) a platinum anode, '~
(2) a reference electrode of Ag/AgCl, (3) an anode in ,."' the form ffl known anodes or in the form of the electrocatalyst of the pre~ent inve~tion, (4) a methane -.
bubbling tube, and (5) a condenqer to trap the volatile products produced during the electrocatalytic proce~s.
The colleoted products in all of the examples were ~ analyzed by ga~ chromatography. The electrical :~ paramet~r~ ~mployed in the electrocatalytic processes were controlled by a programmed potentio~tat a~ i~ known in the art.
~: . ,~ . . : , , " . , , .:
`` 2026~
s Three ~eparate runs were carried out using the `~ ele~trochemical cell described above. All of the reaction~ were carried-out at a temperature of 25~
The cell voltage was pulsed at -0.2 volts for lnO
S geconds and then at +0.64 volts for 50 seconds. In the first run the anode e~ployed was a conventional eataly~t compri~ing a Pd wire. The ele~trolytic solution employed in the electrochemical cell was a 0.6 Molar ;~ HC104 ~olution. In the second run the anode employed was a known catalyst co~prising silver particles di~persed on a Pd wire. The electrolytic solution `~
employed in the second run comprised a Qolution of 2 X
10 6 Molar Ag and 0.5 Molar HCl04. Run 3 was conducted using the same anode as employed in Run 2 with an electrolytic solution comprising 2 X 10 Molar ~
Ag+, 0.5 Molar ~Cl04 and 10 3 Molar Fe3 .
The results of the three runs set forth above ~ay be su=marized a~ followsO Run l evidenced a strong methane adsorption on the anode, however, no oxidation products were created. Run 2 was characterized by a co~petitive adsorption of Ag-methane on the anode7 however, again, a~ was the case with Run l, no o~idation -;
products of me~hane were observable. Run 3 re~ulted in a dissolution-rearrangement cycle of silver. A slight ~;~` 25 oxidation of methane was ob~erved but was not readily measurable.
, ' ' ' .. ~, ','~ /, , ~ . ~ . . . ,- , " ; , ,:
.. : .
The foregoing examples demonstrate that known catalysts referred to in the prior art are not suitable a~ electrocatalysts in the electrocatalytic process of , the pre~ent invention.
EXAMPLE II
In order to d~monstrate the catalytic activity of ~-an electrocatalyst in ac~ordance with the precent invention in the electrocatalytic proces~ of the present invention, an electrochemical cell identical to that described in Example I above was employed. The electrolytic solution employed was a O.S Molar HC104 olution. ~he reaction was carried out a~ 25~ and the cell voltage wa~ kept at 0.2 volts for 100 sec~nds and then at +0.64 volts for 50 seconds for one hour.
rhe anode employed compri~ed an electrocatalyst in accordance with the present invention in the for~ of a composite catalyst co~prising a compact graphite -~
electrode having a geometric area of 48 cm2 having Pd deposited thereon. The Pd wa~ deposited on the co~pact electrode by electrolytic deposition. ~he ' electrocatalytic process was carried out as set forth above and the resulting products were identified as ethanol and methanol. In term~ of Pd loading, the yield of methanol was 40 mmol mpd ana the ~ield of ethanol was 5 ~mol mp2.
?~ , . , , , , :
,~, . . ~ , , : . ~ , , , , ; ... . . .
` - 2 0 2 ~
~( The foregoing demon~trates that the electrocatalyst of the present invention i8 effe~tive for the oxidation of methane by the electrocatalytic process of the present invention.
EXAMPLE III
In order to demonstrate the preferred ~tructure of ~i the electrocatalyst of the present invention, four runs ~-were used employing different electrocatalysts in accordance with the pre~ent invention. In each run the electrolytic olution was a 0.5 Molar NaOH and the cell ~`
voltage was kept constant at +300 mV.
In the fir~t run Pd particles wexe electrolytically disper~ed on a graphite xod in accordance with the present invention. Approximately 25 mg of Pd was depo~ited on the graEhite rod ana the particle size of the Pd on average was about 400 ym.
~ In Run 2 the anode consisted of Pd particle~ in the ¦ amount and ize set forth above with regard to Run l deposited on a steel plate in the same manner a~ Run l.
In Run 3 the anode consisted of an electrocatalyst ``~
having Pd particle~ of the size de cribed above deposited on a Pd wire. In thi~ third run the total amount of Pd used in the composite electrocatalyst waY
10 grams thus making the electrocataly~t extremely expensive. The Pd wa~ depo~ited electrolytically. ~-, ~.,.
-15~
2026~
. 89-328 .,' ~
The fourth run employed a preferred electrocatalyst ~;~
as the anode which consisted of a steel electrode deposited with a layer of conduct.ing polymer, polypirrol, upon whic~ the fine size Pd particles of Runs 1-3 were di~persed in an ~mount of approximately 25 ~-; mg of Pd. The Pd was deposited e~ectrolytically. ~ -The results of ~xample III are set forth below in Table I.
: "'.`:'~", .~
~ ' `
: .
. ~.
: ' .
'~
1~ .
.
-16~
~Ji ':-, ! .: . : , : ` . : . :: , : :: , . .
: 2~2~54 ~
: .
8~-328 U ~
C~
~ '~
g ~ o - -C~ Z Z Z ~ "
. ~
o o ~ 3 " ~q . .`,' ;
` ~ . ,.
....;..
.~` ~ . .~-:~ .; .. .:
~ -17-~ 0 2 ~
, . .
~, . As can be seen from Table I, the catalytic activity, that is, the conver~ion of ~ethane per gram of catalyst was far superior in Run 4 where Pd was deposited on an electrode coated with polypirrol. ~he catalytic activity of the catalyst of Run 4 was approximately five times greater than that obtained in the second best run, that is, ~un l. In addition, Run 4 yielded methanol, ~thanol, propanol and acetone. None of the other runs yielded all four of the~e products.
As can be ~een from the foregoing, a catalyst wherein a layer of conducting polymer is employed allows for superior catalytic activity while, at the same time, requiring les~ catalyst. Thi8 superiox result is believed to be attributable to the fact that the Pd particles may be more evenly dispersed on the poly~er layer.
~ "
EXAMPLE IV
- _ _ __ The electrochemi~al cell de~cribed above may be used as a fuel cell. In order to demon~trate the foregoing, the electrochemical cell was identical to j , :
that described above with regard to Example II except ` that the cathodic rea~tion was an oxidation reduction I reaction wherein oxygen was fed to the cathode to :t~ produce H20. No current ~as appliea. The chemical ~, ~18-2026~
~, ,-products obtained were similar to those obtained in Example II as set forth above; however, a net favorable energy balance was producea without the need of applying an external power source. ~hi~ is extremely important `:`
in that the reaction is energy efficient.
EXAMPLE V ;
In order to demon~trate the effect of hydrogen loading on the electrocatalyst of the pre~ent invention, ;:-the electrochemical cell set up in E~ample III above was --employed using an electrocatalyst a~ the anode ~`
: comprising Pd particles deposited electrolytically on Pd -,-~;~ ; foil. A first run was conducted wherein methane wa~ fed ..
to the electrocatalyst. In a second run the electrocatalyst was loaded with hydrogen by feeding : 15 bydrogen to the electrocatalyst using an electrical .
~: current of l.l mamp CM 2. The result~ of these runs are set forth in Table II below. `~
: ~
T~BLE II
Description EtOR PrOH ~e2CO
Pd/Pd R2-free 22 17 Pd/Pd H2 run 87 233 : , .
~:: , 202~
As can be clearly ~een, Run 2 in which the electrocataly~t was ~oaded with hydrogen showed far -~
greater conversion of methane than that run conducted ~;
without hydrogen loading of the electrocatalyst.
The electrocataly~t of the present invention allows for the conversion of methane to ~ore valuable products via an electrocatalytic process. The process ana - electrocatalyst of the present invention offer~ superior advantage~ over other known processes for the oxidation of methane.
This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristic~ thereof. The present embodiment is therefore to be considered as in all respects illustrative and not restrictive, the ~cope of the invention being indicated by the appended claim~, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.
.' ~'.,.
:
-20~
: 89-328 :1 Accordingly, it is a principal object of the 3 present invention to provide an i.mprovea - electrocatalytic process for the parti.al oxidation of a methane containing gas.
It is a particular object of the present invention , -to provide an improved e.lectxocatalyst for use in the electrocatalytic process as set forth above. ~;.
! It is a ~till fuxther object of the present invention to provide an improved electrocatalyst .~.`
comprising a composite electrocatalyst comprising a ...
s electrode having a finely dispersed conducti.ng catalyst .-:
disposed thereon.
Further objects and advantages of the present -invention will appear hexeinbelow. -.,':,..'~
SUMN~RY OP THE INVENTION
The present invention is drawn to an improved ,~
electrocataly~t and an improved electrocata.lytic process .;;-~
for converting methane to higher value hydrocarbons by ... ;~
the partial oxidation thereof.
The electrocatalyst of the present invention comprises a composite electrocataly t consisting o~ an .
electrode having a finely di.spersed conducting ca~alyst ~.
layer deposited thereon. The electrode compxises a material selected from the group consisting of metal.s, '',.
-3~
~`- 2 ~ 2 ~
j 89-328 ~etal alloys, non-metal conducting materials and mixture~ thereof. In accordance with the present invention, the metals and meta~ alloys used in forming the electrode of the composite electrocatalyst contain ,Aj 5 an element selected from the group consisting of Group .:~-IB metals, Group VIB metals, Group VIII metals and `-mixtures thereof. Suitable non-metal conducting --;
materials for forming the electrode of the --¦ electrocatalyst of the present invention are selectedfrom the group consisting of carbon derived materials, ceramics, polymers, metal oxides and mixtures thereof.
The finely dispersed conducting catalyst deposited on the electrode compri~es an element selected from the group consi~ting of Group IB metals, Group VIB metals, Group VIII metals and mixtures thereof. The material ~
from which the electrode is made may be in the orm of a , rod, grid, plate or felt material. In a preferred embodiment of the present invention, the electrode is covered with ~ layer of a conducting polymer and the finely dispersed aonducting catalyst is deposited on t~e conducting polymer. Suitable materials from which the conducting polymer is formed include teflon, ¦~ polyaniline, polypirrol, per~luorinate~ membranes, polymeric fluorocarbon copolymer, acrylic polymers, metacrylic polymers and mixtures thereof.
, ,~,', . ,~:' " . ~ , ,j j ,, .,, , . ., , . ,. ~ ,. , ~;. " ,, ,,~ ,......... ..
2~26~
8~-328 , ~
The process of the present invention comprises an i electrocatalytic process for partial oxidation of a ~; methane containing gas which aavantageously combines the advantages of both an electr,Dlytic process and cata]ytic -~
process for converting methane to a higher value hydrocarbon. The electrolytic process comprises ~;
preparing the composite electrocatalyst of the present.-invention as set orth above and thereater contacting a methane containing gas with the composite electrocatalyst in an electrolytic cell under ~-electrochemical conditions so as to partially oxidize the methane.
The process of the present invention employing the electrocatalyst of the present invention offers an efficient and economical mechanism~for converting methane to more valuable hydrocarbon products.
DETAILED~DESCRIPTION
The present invention i6 drawn to an improved electrocataly t and an improved electrocatalytic~pxocess and, more particularly, a compo~ite electrocatalyst for use in the partial oxidation of methane by an elec~rolytic proces In accordance with the process of the present invention, methane is oxidized in an electrolytlc cell ::~ :,;
i, ~ . :.,.~.
7 ~ ~
-- 2~26~4 ` .~,., , having an anode, a cathode and an electrolyte solution media. In accordance with the present invention, the ~ -anode i~ in the for~ of the electrocatalyst of the ,`
present invention, the details of which will be set --forth hereinbelow. The electrochemical proces3 of the -- `
invention results in the partial oxidation of ~ethane forming a methane containing gas to yield oxigenated hydrocarbon of light molecular weight under moderate proces3ing conditions. -~
The proce~s of the present invention employs a ~-~tandard electrolytic cell. In the ca~e of a compact electrocatalyst, that is where the~finely di~per~ed catalyst material i8 depo~ited on a non-porous -`
electrode, the procedure involves the reactant gas, in thig case a methane ~ontaining gas, diffusing towards the electrocatalyst of the present invention throug~ an electrolytic solution in which a cathode is al80 immer~ed. Where a porous electrocatalyat iB employed, ~ ~
that i8 where the catalyst io in the form of a finely ~;
di3per~ed pQrticle deposited on a porous electrode, i.e. ~`
felt material, grid or the like, the reactant gas would preferably diffuse through the porous electrod~ in order to avoid gas ~olubility and diffusion limitations. The foregoing are typical of standard electrolytic ~-~
operations.
~ ' ' ."~'' , -6- ~
~.... , , ... . , , , . . .. ~ -;
202~4 The reactant gases used in the proce~s of the present invention comprise p1are methane, met~ane diluted in hydrogen and an alternating pulse of methane and hydrogen. During the electrolytic operation, when pure methane i~ employed as the reactant gas, the methane ~-`
constantly flows towards or through the electrocatalyst. When diluted methane i8 u~ed as a reactant ga~, the methane flows towards or through the electrocatalyst in a constant or pulsed manner with ~
~1 10 hydrogen or alternately with hydrogen and methane. By ' ~.~'~!''.' loading the eloctrocatalyst with hydrogen, the catalytic activity is improved. ~`~
The electrolytic solution used in the process of ; the present invention may be an acid, a basic or a ~; 15 neutral pH solution. Typical acid solutions include sulphuric acid, perchloric acid and ~he likeO Typical base solutions includo sodium hydroxide, ammonium hydroxide and the 11ke. In addition, ionic 3alt~ ~ight be used as the electrolytic ~olution. Such salts include pota~sium nitrate, sodium nulfate and tho like.
In addition, ionic mediator~ such a~ Fe(III), Cr~
Co(III), Ce(IV) or Cd(II) ~ight also be used in solution.
;~ As noted~above, the anode emp]oyed in the process of the prenent invention i8 in the form of an electxocatalyst in accordance with the present _ i3' ` 2~2~5~
~ 89-328 "''" ' ".
invention. The electrocatalyst i8 a composite electrocatalyst comprising an electrode having a finely ;~
dispersed electronically conductive catalyst deposited thereon. The catalyst may bc~ deposited in any known manner depending on it~ form ~uch a~ by painting, electronically deposited, etc. The electrode can be in the form of a compact or porous material such as, or example, a rod, a plate, a grid or felt material. The ~-,.
material from which the electrode i8 formed is selected ; 10 from the group of materials consisting of metals, metal l alloys, non-metal conducting materials and mixtures thereof. The metals and ~etal alloys whic~ form the electrode of the composite electrode catalyst contain an element selected from the group consisting of Group IB
metals, Group VIB metals, Group VIII metals and mi~tures thereof. Particularly suitable materials contain an ~1 element selectea fro~ the group consisting of Au, ~e, Ag, Pt, Ir, Rh, Pd, Steel, Mo, Ni and mi~tures thereof.
The most preferred materials from which the electrode i~
3i 20 formed contain an ele~ent ~elected from the group con~isting of Ag, Fe, Steel, ~i and mixtures thereof. ~
In the event the electrode i8 formed from a non-metal ~;
conducting material, the non-metal conducting materials most suitable are selected from the group consi~ting of i 25 carbon derived materials, ceramics, polymers, metal oxides and mixtures thereof. ~ -~
~" ,',, ~; ' ". ' " ' ' ' ' : , ' , ~?;- ~
,~ ;, .. ~ .
2~26~5~ ~ ~
, ', . -~ .
The catalyst deposited on the electrode is a fin~ly disper~ed conducting materia]L which contains an element selected from the group consiRting of Group IB metals, Group VIB metals, Group VIII metals and mi~tures d 5 thereof. The cataly~t material iR finely dispersed on the electrode in known manner a~ i8 commonly practiced a~ descxibed above.
It has been found that the smaller the particle --si~e of the finely dispersed cataly~t material, the better the catalytic activity a~sociated with the electrocatalyst. The particle size of the material particle di~persed on the electrode i9 about between ~
0.0001 pm to about 800 ~m and preferably from about `-`
0.001Jum to about 200 ~m. The thickness of the finely ~ -~
lS aisper~ed conducting catalyst layer shoula be a~ uniform -as possiblo in order to provide effective activity. The thickness requirements of the dspersed conducting catalyst layer are balanced 80 aB ~0. in~ure structural integrity while at the same time employing an economic amount of catalyst material. It has been found that catalyst layers of 0.01 ~m exhibit the necessary ; structural integrity and, generally, thicknesse~ o~
¦ ~ greater than 2 ~m are undesirable for economic reasons.
In a preferred embodiment of the electrocatalyst of the present invention, a conducting polymer layer i~
, , `,~`,.. '.
. .,~
~S
2 0 2 ~
l 89-328 .' .-, deposited on the electrode and the fin~ly disper~ed catalyst ~aterial is deposited on the conducting polymer ~-material. The presence of the conducting polymer improves the dispersion of the finely ~eposited cataly~t on the electrode thereby requiring u~e of less catalyst --material. Suitable conducting polymer material~ are 3 selected from the group consi~ting of teflon, ~ polyaniline, polypirrol, perfluorinated membrane~, '1 : , ~ polymeric fluorocarbon copol~mer, acrylic poly~er~, ~
~s ~1 10 metacrylic polymers and mixtures thereof and the mo~t ¦~ ~ preferred materials are gelected from the group consigting of poIypirrol and perfluorinated polymer~ and mixtures thereof. The thicknes of the conducting polymer layers ghould not exceed 5.0 ym and, preferably ghould not exceed l.0 ~m in order to avoid unreasonable electrical resistance.
The electrolytic cell ~ay be operated in the mode -;
of a fuel cell by the reduction of o~ygen at the cathode 80 as to produce ~2 When the cell i8 operated in this mode, no electrical current need be applied. The -~
chemical products obtained when operating the electroche~ical cell as a fuel cell are similar to those --obtained when operating the electrolytic cell under the process conditions set forth below. The advantage of `--operating the electrochemical cell as a fuel cell i~ -. ' ' -10- ' 2 0 2 ~ 3~i 4 that no electrical cu~rent need be applied. This operation is exemplified hereinbelow in Example IV. ;~
As noted above, the proce~s of the present invention combine~ ele~trolytic proce~ing t~chnology and catalytic proce-~sing technology for converting methane to a higher oxidized product. The electrocatalytic process of the pre~ent invention is conducted under the following operating parameter~
Temperature: 0 - 200C, preferably 20 to 70C; ~;~
Pressure : 0.5 - lO0 atm., preferably 0.8 to 30 atms. ,.,.`
Voltage : 0 to 20 volts applied either constant, alternating or pulses; and Current : 0 to l.0 amps cm 2, preferably 0 to 0.5 amps cm 2 applied either ;~
constant, alternating or pul~ed.
,~
By loading the electrocatalyst with hydrogen, that i8, ~eeding hydrogen to the electrocataly~t with methane pulsing alternating with methane and hydrogen, the conver~ion of methane per gram of catalys~ i3 i~proved, : .
i.e., catalyst activity. A~ noted above, ~ethane may be fed to the electrocatalyst either with hydrogen or alternating pul~ed ~ith hydrogen and methane.
' . .'`,~
-11- . .'. ."
.! ~ 2 ~ 2 ~ ~ 5 4 .
`, , .
In addition, the cathode of the electrochemical cell may take the form of th~e compo~ite electrocata],yst described above. In t~i~ ca~e, the anode and cathode may be selectively alternated during the electrolytic process thereby extending the life of the elements.
The inve~tion will be fur~her illustrated by the following example~ which are in no way int0nded to be ', L . limiting. ~' EXAMPLE I
Example I wa~ run in order ~o demonstrate that;~'.
known catalysts used in the oxidation of methane are ~.`
ineffective when employed in the electrocatalytic ~ , proce-cs in accordance with the present invention. The electrochemical cell employed in the e~amples is of~p lS known construction and con~ist~ of (1) a platinum anode, '~
(2) a reference electrode of Ag/AgCl, (3) an anode in ,."' the form ffl known anodes or in the form of the electrocatalyst of the pre~ent inve~tion, (4) a methane -.
bubbling tube, and (5) a condenqer to trap the volatile products produced during the electrocatalytic proce~s.
The colleoted products in all of the examples were ~ analyzed by ga~ chromatography. The electrical :~ paramet~r~ ~mployed in the electrocatalytic processes were controlled by a programmed potentio~tat a~ i~ known in the art.
~: . ,~ . . : , , " . , , .:
`` 2026~
s Three ~eparate runs were carried out using the `~ ele~trochemical cell described above. All of the reaction~ were carried-out at a temperature of 25~
The cell voltage was pulsed at -0.2 volts for lnO
S geconds and then at +0.64 volts for 50 seconds. In the first run the anode e~ployed was a conventional eataly~t compri~ing a Pd wire. The ele~trolytic solution employed in the electrochemical cell was a 0.6 Molar ;~ HC104 ~olution. In the second run the anode employed was a known catalyst co~prising silver particles di~persed on a Pd wire. The electrolytic solution `~
employed in the second run comprised a Qolution of 2 X
10 6 Molar Ag and 0.5 Molar HCl04. Run 3 was conducted using the same anode as employed in Run 2 with an electrolytic solution comprising 2 X 10 Molar ~
Ag+, 0.5 Molar ~Cl04 and 10 3 Molar Fe3 .
The results of the three runs set forth above ~ay be su=marized a~ followsO Run l evidenced a strong methane adsorption on the anode, however, no oxidation products were created. Run 2 was characterized by a co~petitive adsorption of Ag-methane on the anode7 however, again, a~ was the case with Run l, no o~idation -;
products of me~hane were observable. Run 3 re~ulted in a dissolution-rearrangement cycle of silver. A slight ~;~` 25 oxidation of methane was ob~erved but was not readily measurable.
, ' ' ' .. ~, ','~ /, , ~ . ~ . . . ,- , " ; , ,:
.. : .
The foregoing examples demonstrate that known catalysts referred to in the prior art are not suitable a~ electrocatalysts in the electrocatalytic process of , the pre~ent invention.
EXAMPLE II
In order to d~monstrate the catalytic activity of ~-an electrocatalyst in ac~ordance with the precent invention in the electrocatalytic proces~ of the present invention, an electrochemical cell identical to that described in Example I above was employed. The electrolytic solution employed was a O.S Molar HC104 olution. ~he reaction was carried out a~ 25~ and the cell voltage wa~ kept at 0.2 volts for 100 sec~nds and then at +0.64 volts for 50 seconds for one hour.
rhe anode employed compri~ed an electrocatalyst in accordance with the present invention in the for~ of a composite catalyst co~prising a compact graphite -~
electrode having a geometric area of 48 cm2 having Pd deposited thereon. The Pd wa~ deposited on the co~pact electrode by electrolytic deposition. ~he ' electrocatalytic process was carried out as set forth above and the resulting products were identified as ethanol and methanol. In term~ of Pd loading, the yield of methanol was 40 mmol mpd ana the ~ield of ethanol was 5 ~mol mp2.
?~ , . , , , , :
,~, . . ~ , , : . ~ , , , , ; ... . . .
` - 2 0 2 ~
~( The foregoing demon~trates that the electrocatalyst of the present invention i8 effe~tive for the oxidation of methane by the electrocatalytic process of the present invention.
EXAMPLE III
In order to demonstrate the preferred ~tructure of ~i the electrocatalyst of the present invention, four runs ~-were used employing different electrocatalysts in accordance with the pre~ent invention. In each run the electrolytic olution was a 0.5 Molar NaOH and the cell ~`
voltage was kept constant at +300 mV.
In the fir~t run Pd particles wexe electrolytically disper~ed on a graphite xod in accordance with the present invention. Approximately 25 mg of Pd was depo~ited on the graEhite rod ana the particle size of the Pd on average was about 400 ym.
~ In Run 2 the anode consisted of Pd particle~ in the ¦ amount and ize set forth above with regard to Run l deposited on a steel plate in the same manner a~ Run l.
In Run 3 the anode consisted of an electrocatalyst ``~
having Pd particle~ of the size de cribed above deposited on a Pd wire. In thi~ third run the total amount of Pd used in the composite electrocatalyst waY
10 grams thus making the electrocataly~t extremely expensive. The Pd wa~ depo~ited electrolytically. ~-, ~.,.
-15~
2026~
. 89-328 .,' ~
The fourth run employed a preferred electrocatalyst ~;~
as the anode which consisted of a steel electrode deposited with a layer of conduct.ing polymer, polypirrol, upon whic~ the fine size Pd particles of Runs 1-3 were di~persed in an ~mount of approximately 25 ~-; mg of Pd. The Pd was deposited e~ectrolytically. ~ -The results of ~xample III are set forth below in Table I.
: "'.`:'~", .~
~ ' `
: .
. ~.
: ' .
'~
1~ .
.
-16~
~Ji ':-, ! .: . : , : ` . : . :: , : :: , . .
: 2~2~54 ~
: .
8~-328 U ~
C~
~ '~
g ~ o - -C~ Z Z Z ~ "
. ~
o o ~ 3 " ~q . .`,' ;
` ~ . ,.
....;..
.~` ~ . .~-:~ .; .. .:
~ -17-~ 0 2 ~
, . .
~, . As can be seen from Table I, the catalytic activity, that is, the conver~ion of ~ethane per gram of catalyst was far superior in Run 4 where Pd was deposited on an electrode coated with polypirrol. ~he catalytic activity of the catalyst of Run 4 was approximately five times greater than that obtained in the second best run, that is, ~un l. In addition, Run 4 yielded methanol, ~thanol, propanol and acetone. None of the other runs yielded all four of the~e products.
As can be ~een from the foregoing, a catalyst wherein a layer of conducting polymer is employed allows for superior catalytic activity while, at the same time, requiring les~ catalyst. Thi8 superiox result is believed to be attributable to the fact that the Pd particles may be more evenly dispersed on the poly~er layer.
~ "
EXAMPLE IV
- _ _ __ The electrochemi~al cell de~cribed above may be used as a fuel cell. In order to demon~trate the foregoing, the electrochemical cell was identical to j , :
that described above with regard to Example II except ` that the cathodic rea~tion was an oxidation reduction I reaction wherein oxygen was fed to the cathode to :t~ produce H20. No current ~as appliea. The chemical ~, ~18-2026~
~, ,-products obtained were similar to those obtained in Example II as set forth above; however, a net favorable energy balance was producea without the need of applying an external power source. ~hi~ is extremely important `:`
in that the reaction is energy efficient.
EXAMPLE V ;
In order to demon~trate the effect of hydrogen loading on the electrocatalyst of the pre~ent invention, ;:-the electrochemical cell set up in E~ample III above was --employed using an electrocatalyst a~ the anode ~`
: comprising Pd particles deposited electrolytically on Pd -,-~;~ ; foil. A first run was conducted wherein methane wa~ fed ..
to the electrocatalyst. In a second run the electrocatalyst was loaded with hydrogen by feeding : 15 bydrogen to the electrocatalyst using an electrical .
~: current of l.l mamp CM 2. The result~ of these runs are set forth in Table II below. `~
: ~
T~BLE II
Description EtOR PrOH ~e2CO
Pd/Pd R2-free 22 17 Pd/Pd H2 run 87 233 : , .
~:: , 202~
As can be clearly ~een, Run 2 in which the electrocataly~t was ~oaded with hydrogen showed far -~
greater conversion of methane than that run conducted ~;
without hydrogen loading of the electrocatalyst.
The electrocataly~t of the present invention allows for the conversion of methane to ~ore valuable products via an electrocatalytic process. The process ana - electrocatalyst of the present invention offer~ superior advantage~ over other known processes for the oxidation of methane.
This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristic~ thereof. The present embodiment is therefore to be considered as in all respects illustrative and not restrictive, the ~cope of the invention being indicated by the appended claim~, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.
.' ~'.,.
:
-20~
Claims (53)
1. A composite electrocatalyst comprising an electrode having a finely dispersed conducting catalyst deposited thereon wherein:
(1) said electrode comprises a material selected from the group consisting of metals, metal alloys, non-metal conducting materials and mixtures thereof wherein:
(a) said metals and metal alloys contain an element selected from the group consisting of Group IB metals, Group VIB
metals, Group VIII metals and mixtures thereof; and (b) said non-metal conducting materials are selected from the group consisting of carbon derived materials, ceramics, polymers, metal oxides and mixtures thereof: and (2) said catalyst comprises a finely dispersed metal particle comprising an element selected from the group consisting of Group IB metals, Group VIB metals, Group VIII metals and mixtures thereof.
(1) said electrode comprises a material selected from the group consisting of metals, metal alloys, non-metal conducting materials and mixtures thereof wherein:
(a) said metals and metal alloys contain an element selected from the group consisting of Group IB metals, Group VIB
metals, Group VIII metals and mixtures thereof; and (b) said non-metal conducting materials are selected from the group consisting of carbon derived materials, ceramics, polymers, metal oxides and mixtures thereof: and (2) said catalyst comprises a finely dispersed metal particle comprising an element selected from the group consisting of Group IB metals, Group VIB metals, Group VIII metals and mixtures thereof.
2. A composite electrocatalyst according to claim 1 wherein the particle size of said metal particle is between about 0.0001 µm to about 800 µm.
3. A composite electrocatalyst according to claim 1 wherein the particle size of said metal particle is between about 0.001 µm to about 200 µm.
4. A composite electrocatalyst according to claim 1 wherein the conducting catalyst has a thickness of less than or equal to 2 µm wherein the thickness is substantially uniform.
5. A composite electrocatalyst according to claim 3 wherein the average thickness of said finely dispersed conducting catalyst is from about .01 µm to about .10 µm.
6. A composite electrocatalyst according to claim 1 wherein said electrode is formed of a material selected from the group consisting of rod, grid, plate and felt materials.
7. A composite electrocatalyst according to claim 1 wherein said electrode material contains a element selected from the group consisting of Au, Fe, Ag, Pt, Ir, Rh, Pd, Steel, Mo, Ni and mixtures thereof.
8. A composite electrocatalyst according to claim 1 wherein said electrode material contains a element selected from the group consisting of Ag, Fe, Steel, Ni and mixtures thereof.
9. A composite electrocatalyst according to claim 1 wherein said electrode comprises a non-metal conducting material selected from the group consisting of graphite and ceramic material.
10. A composite electrocatalyst according to claim 1 wherein said catalyst comprises an element selected from the group consisting of Ni, Mo, Co, Pd, Ir, Rh, Ru, Pt, Fe, Ag and mixtures thereof.
11. A composite electrocatalyst according to claim 1 wherein said catalyst comprises a finely dispersed material particle containing an element selected from the group consisting of Ni, Pd, Ir, Ru and mixtures thereof.
12. A composite electrocatalyst according to claim 1 wherein said electrode is covered by a layer of a conducting polymer and said finely dispersed conducting catalyst is deposited on said conducting polymer.
13. A composite electrocatalyst according to claim 12 wherein said conducting polymer is selected from the group consisting of teflon, polyaniline, polypirrol, perfluorinated membranes, polymeric fluorocarbon copolymer, acrylic polymers, metacrylic polymers and mixtures thereof.
14. A composite electrocatalyst according to claim 13 wherein said polymer is selected from the group consisting of polypirrol and perfluorinated polymers and mixtures thereof.
15. A composite electrocatalyst according to claim 12 wherein the thickness of the conducting polymer layer is less than or equal to about 5.0 µm.
16. A composite electrocatalyst according to claim 15 wherein the thickness of the conducting polymer layer is less than or equal to about 1.0 µm.
17. An electrocatalytic process for the partial oxidation of a methane-containing gas in an electrochemical cell having an anode and a cathode which comprises:
(1) preparing an anode in the form of a composite electrocatalyst comprising an electrode having a finely dispersed conducting catalyst material deposited thereon, said catalyst material comprising an element selected from the group consisting of Group IB metals, Group VIB metals, Group VIII metals and mixtures thereof; and (2) contacting said methane-containing gas with said composite electrocatalyst in the electrochemical cell under electrochemical conditions so as to partially oxidize said methane.
(1) preparing an anode in the form of a composite electrocatalyst comprising an electrode having a finely dispersed conducting catalyst material deposited thereon, said catalyst material comprising an element selected from the group consisting of Group IB metals, Group VIB metals, Group VIII metals and mixtures thereof; and (2) contacting said methane-containing gas with said composite electrocatalyst in the electrochemical cell under electrochemical conditions so as to partially oxidize said methane.
18. An electrocatalytic process according to claim 17 wherein:
(1) said anode comprises a material selected from the group consisting of metals, metal alloys, non-metal conducting materials and mixtures thereof wherein:
(a) said metals and metal alloys contain an element selected from the group consisting of Group IB metals, Group VIB
metals, Group VIII metals and mixtures thereof; and (b) said non-metal conducting materials are selected from the group consisting of carbon derived materials, ceramics, polymers, metal oxides and mixtures thereof.
(1) said anode comprises a material selected from the group consisting of metals, metal alloys, non-metal conducting materials and mixtures thereof wherein:
(a) said metals and metal alloys contain an element selected from the group consisting of Group IB metals, Group VIB
metals, Group VIII metals and mixtures thereof; and (b) said non-metal conducting materials are selected from the group consisting of carbon derived materials, ceramics, polymers, metal oxides and mixtures thereof.
19. An electrocatalytic process according to claim 18 wherein the particle size of said metal particles is between about 0.0001 µm to about 800 µm.
20. An electrocatalytic process according to claim 17 wherein the particle size of said metal particle is between about 0.001 µm to about 200 µm.
21. An electrocatalytic process according to claim 17 wherein the finely dispersed conducting catalyst has a thickness of less than or equal to 2 µm wherein the thickness is substantially uniform.
22. An electrocatalytic process according to claim 20 wherein the average thickness of said finely dispersed conducting catalyst is from about .01 µm to about .10 µm.
23. An electrocatalytic process according to claim 17 wherein said electrode or anode is formed of a material selected from the group consisting of rod, grid, plate and felt materials.
24. An electrocatalytic process according to claim 17 wherein said electrode material contains a element selected from the group consisting of Au, Fe, Ag, Pt, Ir, Rh, Pd, Steel, Mo, Ni and mixtures thereof.
25. An electrocatalytic process according to claim 17 wherein said electrode material contains a element selected from the group consisting of Ag, Fe, Steel, Ni and mixtures thereof.
26. An electrocatalytic process according to claim 17 wherein said electrode comprises a non-metal conducting material selected from the group consisting of graphite and ceramic material.
27. An electrocatalytic process according to claim 17 wherein said catalyst comprises a finely dispersed metal particle containing an element selected from the group consisting of Ni, Mo, Co, Pd, Ir, Rh, Ru, Pt, Fe, Ag and mixtures thereof.
28. An electrocatalytic process according to claim 17 wherein said catalyst comprises a finely dispersed material particle containing an element selected from the group consisting of Ni, Pd, Ir, Ru and mixtures thereof.
29. An electrocatalytic process according to claim 17 wherein said electrode is covered by a layer of a conducting polymer and said finely dispersed conducting catalyst is deposited on said conducting polymer.
30. An electrocatalytic process according to claim 29 wherein said conducting polymer is selected from the group consisting of teflon, polyaniline, polypirrol, perfluorinated membranes, polymeric fluorocarbon copolymer, acrylic polymers, metacrylic polymers and mixtures thereof.
31. An electrocatalytic process according to claim 30 wherein said polymer is selected from the group consisting of polypirrol and perfluorinated polymers and mixtures thereof.
32. An electrocatalytic process according to claim 29 wherein the thickness of the conducting polymer layer is less than or equal to about 5.0 µm.
33. An electrocatalytic process according to claim 32 wherein the thickness of the conducting polymer layer is less than or equal to about 1.0 µm.
34. An electrocatalytic process according to claim 17 wherein said electrocatalytic process is conducted under the following conditions:
voltage: up to 20 volts current: up to 1.0 A cm-2.
voltage: up to 20 volts current: up to 1.0 A cm-2.
35. An electrocatalytic process according to claim 34 including applying said voltage and current as pulses.
36. An electrocatalytic process according to claim 34 including applying said voltage and current as alternating pulses.
37. An electrocatalytic process according to claim 34 including applying said voltage and current as constant pulses.
38. An electrocatalytic process according to claim 34 including forming the electrocatalyst with a compact electrode.
39. An electrocatalytic process according to claim 34 including forming the electrocatalyst with a porous electrode.
40. An electrocatalytic process according to claim 34 including applying a voltage of up to 2.0 volts.
41. An electrocatalytic process according to claim 40 including applying a current of up to 0.5 A cm-1.
42. An electrocatalytic process according to claim 34 including carrying out said electrolytic process at a temperature of up to 200°C.
43. An electrocatalytic process according to claim 42 including carrying out said electrolytic process at a temperature of about between 20 to 70°C.
44. An electrocatalytic process according to claim 34 including conducting the electrolytic process at a pressure of between 0.5 to 100 atms.
45. An electrocatalytic process according to claim 34 including conducting the electrolytic process at a pressure of between 0.8 to 30 atms.
46. An electrocatalytic process according to claim 19 including feeding hydrogen to said electrocatalyst so as to load same with hydrogen.
47. An electrocatalytic process according to claim 46 wherein said hydrogen is fed with said methane.
48. An electrocatalytic process according to claim 46 wherein said hydrogen is pulsed alternately with said methane.
49. An electrocatalytic process according to claim 17 including feeding oxygen to said cathode wherein said electrochemical cell acts as a fuel cell.
50. An electrocatalytic process according to claim 17 wherein said cathode is in the form of the composite electrocatalyst of claim 18.
51. An electrocatalytic process according to claim 50 wherein said cathode comprises a finely dispersed metal particle containing an element selected from the group consisting of Ni, Mo, Co, Pd, Ir, Rh, Ru, Pt, Fe, Ag and mixtures thereof.
52. An electrocatalytic process according to claim 51 wherein said cathode comprises a finely dispersed metal particle containing an element selected from the group consisting of Ni, Pd, Ir, Ru and mixtures thereof.
53. An electrocatalytic process according to claim 50 wherein said anode and said cathode are periodically alternated during said electrochemical operation.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/472,867 US5051156A (en) | 1990-01-31 | 1990-01-31 | Electrocatalyst for the oxidation of methane and an electrocatalytic process |
| US472,867 | 1990-01-31 | ||
| JP3031624A JPH0665773A (en) | 1990-01-31 | 1991-01-31 | Electrocatalyst and electrocatalyst method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2026554A1 true CA2026554A1 (en) | 1991-08-01 |
Family
ID=26370129
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002026554A Abandoned CA2026554A1 (en) | 1990-01-31 | 1990-09-28 | Electrocatalyst for the oxidation of methane and an electrocatalytic process |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5051156A (en) |
| JP (1) | JPH0665773A (en) |
| CA (1) | CA2026554A1 (en) |
| DE (1) | DE4040835A1 (en) |
| GB (1) | GB2261384A (en) |
Families Citing this family (27)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19530512C1 (en) * | 1995-08-18 | 1996-10-17 | Siemens Ag | Electrical layered contact element used in weak current relays |
| US6294068B1 (en) * | 1997-06-20 | 2001-09-25 | Natural Resources Canada | Electrochemical conversion of hydrocarbons |
| US5900385A (en) * | 1997-10-15 | 1999-05-04 | Minnesota Mining And Manufacturing Company | Nickel--containing compounds useful as electrodes and method for preparing same |
| FR2775622A1 (en) * | 1998-03-03 | 1999-09-03 | Atochem Elf Sa | SUPPORTED BIMETALLIC CATALYZER BASED ON PLATINUM OR SILVER, ITS MANUFACTURING PROCESS AND ITS USE FOR ELECTROCHEMICAL CELLS |
| AU6396900A (en) * | 1999-08-20 | 2001-03-19 | Medis El Ltd. | A new class of electrocatalysts and a gas diffusion electrode based thereon |
| US6380126B1 (en) | 1999-08-20 | 2002-04-30 | Medis El Ltd | Class of electrocatalysts and a gas diffusion electrode based thereon for fuel cells |
| US6878664B1 (en) | 2001-01-16 | 2005-04-12 | Medis El Ltd. | Class of electrocatalysts and a gas diffusion electrode based thereon for fuel cells |
| US6939640B2 (en) * | 2001-09-21 | 2005-09-06 | E. I. Dupont De Nemours And Company | Anode electrocatalysts for coated substrates used in fuel cells |
| DE10238912A1 (en) * | 2002-08-24 | 2004-03-11 | Mtu Cfc Solutions Gmbh | Electronically conducting reforming catalyst for a fuel cell contains particles of a water-adsorbing electronically conducting substrate material and particles of a catalyst material arranged on the substrate material |
| US7632601B2 (en) * | 2005-02-10 | 2009-12-15 | Brookhaven Science Associates, Llc | Palladium-cobalt particles as oxygen-reduction electrocatalysts |
| US7498286B2 (en) * | 2005-05-23 | 2009-03-03 | Board Of Regents, The University Of Texas System | Electrocatalyst for oxygen reduction reaction in proton exchange membrane fuel cells |
| US20060264321A1 (en) * | 2005-05-23 | 2006-11-23 | Board Of Regents, The University Of Texas System | Electrocatalysts for oxygen reduction |
| DE102010029966A1 (en) * | 2009-06-10 | 2010-12-16 | Wieland Kg | Improved electrocatalyst, fuel cell cathode and fuel cell |
| US9145615B2 (en) | 2010-09-24 | 2015-09-29 | Yumei Zhai | Method and apparatus for the electrochemical reduction of carbon dioxide |
| EP3269845B1 (en) | 2011-03-26 | 2019-08-14 | Honda Motor Co., Ltd. | Method which produces hydrocarbon transportation fuels |
| US8821715B2 (en) | 2011-05-24 | 2014-09-02 | Saudi Arabian Oil Company | Electrochemical promotion of catalysis in hydrodesulfurization processes |
| US9718046B2 (en) | 2011-05-24 | 2017-08-01 | Saudi Arabian Oil Company | Bimetallic titania-based electrocatalysts deposited on ionic conductors for hydrodesulfurization reactions |
| US9499917B2 (en) | 2012-11-07 | 2016-11-22 | Gas Technology Institute | Non-Faradaic electrochemical promotion of catalytic methane reforming for methanol production |
| US9528190B2 (en) | 2012-11-07 | 2016-12-27 | Gas Technology Institute | Method for producing liquid organic fuels and hydrogen |
| US9163316B2 (en) | 2012-11-07 | 2015-10-20 | Gas Technology Institute | Method for producing methanol from methane |
| US9932679B2 (en) * | 2013-10-31 | 2018-04-03 | Exxonmobil Chemical Patents Inc. | Electrochemical conversion of hydrocarbons |
| US20170314148A1 (en) * | 2016-05-02 | 2017-11-02 | Ut-Battelle, Llc | Electrochemical catalyst for conversion of co2 to ethanol |
| EA202091855A1 (en) * | 2018-02-12 | 2021-04-07 | Траннел Лтд, Ой | METHOD AND DEVICE FOR PRODUCING ALCOHOLS FROM HYDROCARBONS |
| US11591699B2 (en) | 2018-04-12 | 2023-02-28 | Board Of Supervisors Of Louisiana State University | Electrochemical reactor for upgrading methane and small alkanes to longer alkanes and alkenes |
| WO2022072434A1 (en) | 2020-09-30 | 2022-04-07 | Ut-Battelle, Llc | Alloy based electrochemical catalyst for conversion of carbon dioxide to hydrocarbons |
| CN113186561B (en) * | 2021-04-26 | 2022-05-20 | 复旦大学 | Method for promoting electrocatalytic oxidation of methane to generate methyl chloride by using chloride ions |
| FR3131923A1 (en) | 2022-01-18 | 2023-07-21 | Commissariat A L'energie Atomique Et Aux Energies Alternatives | Process for the co-valorization by electrolysis of CO2 and hydrocarbons |
Family Cites Families (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3287171A (en) * | 1963-01-11 | 1966-11-22 | Exxon Research Engineering Co | Platinum-rhenium anodic oxidation catalyst |
| CA920120A (en) * | 1969-03-21 | 1973-01-30 | Charkey Allen | Semi-conductor electrode depolarizer |
| US3798063A (en) * | 1971-11-29 | 1974-03-19 | Diamond Shamrock Corp | FINELY DIVIDED RuO{11 {11 PLASTIC MATRIX ELECTRODE |
| FR2297079A1 (en) * | 1975-01-10 | 1976-08-06 | Anvar | NEW CATALYST FOR ELECTROLYTIC OXIDATION OF HYDROGEN |
| US4235695A (en) * | 1977-12-09 | 1980-11-25 | Diamond Shamrock Technologies S.A. | Novel electrodes and their use |
| CA1137161A (en) * | 1978-04-18 | 1982-12-07 | Ernest H. Lyons, Jr. | Fuel cell with anode containing transition element sulphide |
| US4205194A (en) * | 1978-05-08 | 1980-05-27 | Exxon Research & Engineering Co. | Process for the conversion of relatively low molecular weight hydrocarbons, to higher molecular weight hydrocarbons, catalyst-reagents for such use in such process, and the regeneration thereof |
| IT1130955B (en) * | 1980-03-11 | 1986-06-18 | Oronzio De Nora Impianti | PROCEDURE FOR THE FORMATION OF ELECTROCES ON THE SURFACES OF SEMI-PERMEABLE MEMBRANES AND ELECTRODE-MEMBRANE SYSTEMS SO PRODUCED |
| CA1190185A (en) * | 1980-08-18 | 1985-07-09 | Michael Katz | Electrode with outer coating and protective intermediate conductive polymer coating on a conductive base |
| JPS5948872A (en) * | 1982-09-14 | 1984-03-21 | Comput Basic Mach Technol Res Assoc | Servo signal writing circuit system |
| US4462876A (en) * | 1983-03-25 | 1984-07-31 | Ppg Industries, Inc. | Electro organic method and apparatus for carrying out same |
| DE3423605A1 (en) * | 1984-06-27 | 1986-01-09 | W.C. Heraeus Gmbh, 6450 Hanau | COMPOSITE ELECTRODE, METHOD FOR THEIR PRODUCTION AND THEIR USE |
| JPS6130688A (en) * | 1984-07-23 | 1986-02-12 | Idemitsu Kosan Co Ltd | Production of hydrocarbon |
| JPS6257717A (en) * | 1985-09-06 | 1987-03-13 | Mitsubishi Electric Corp | Automatic metal die changing device for pess brake |
| JPS62163746A (en) * | 1986-01-13 | 1987-07-20 | Nippon Engeruharudo Kk | Platinum alloy electrode catalyst and electrode for acidic electrolyte fuel cell using same |
| JPS62297483A (en) * | 1986-02-13 | 1987-12-24 | Kotaro Ogura | Selective conversion of methane into methanol and chloromethane at ordinary temperature |
| US4802958A (en) * | 1987-03-17 | 1989-02-07 | The Standard Oil Company | Process for the electrocatalytic oxidation of low molecular weight hydrocarbons to higher molecular weight hydrocarbons |
| DE3710168A1 (en) * | 1987-03-27 | 1988-10-13 | Varta Batterie | Method of fabricating a plastic-bound gas-diffusion electrode with metallic fuel-cell catalysts |
| JPH0624635B2 (en) * | 1987-05-19 | 1994-04-06 | ヤンマーディーゼル株式会社 | Highly active catalyst powder for methanol fuel cell and method for producing highly active electrode using the same |
| JP2701153B2 (en) * | 1988-09-30 | 1998-01-21 | 三井東圧化学株式会社 | Method for producing carbonyl compound |
-
1990
- 1990-01-31 US US07/472,867 patent/US5051156A/en not_active Expired - Fee Related
- 1990-06-25 GB GB9014102A patent/GB2261384A/en not_active Withdrawn
- 1990-09-28 CA CA002026554A patent/CA2026554A1/en not_active Abandoned
- 1990-12-20 DE DE4040835A patent/DE4040835A1/en not_active Withdrawn
-
1991
- 1991-01-31 JP JP3031624A patent/JPH0665773A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0665773A (en) | 1994-03-08 |
| GB2261384A (en) | 1993-05-19 |
| GB9014102D0 (en) | 1990-08-15 |
| US5051156A (en) | 1991-09-24 |
| DE4040835A1 (en) | 1991-08-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2026554A1 (en) | Electrocatalyst for the oxidation of methane and an electrocatalytic process | |
| Smith et al. | Electrodes based on Magnéli phase titanium oxides: the properties and applications of Ebonex® materials | |
| Tseung et al. | Hydrogen spill-over effect on Pt/WO3 anode catalysts | |
| US20130228470A1 (en) | Method and apparatus for an electrolytic cell including a three-phase interface to react carbon-based gases in an aqueous electrolyte | |
| Chandler et al. | Electrodes based on noble metals | |
| EP0040031A1 (en) | Anode catalyst and generation of oxygen | |
| GB2073251A (en) | Anode for reducing oxygen generation in the electrolysis of hydrogen chloride | |
| EP0390158B1 (en) | Electrolysis cell | |
| EP0390157B1 (en) | Electrolysis cell and method of use | |
| WO2002027821A2 (en) | Electrode catalyst composition, electrode and membrane electrode assembly for electrochemical cells | |
| GB2508795A (en) | Electrolysis electrocatalyst comprising palladium and iridium | |
| Papaderakis et al. | Hydrogen evolution at Ir-Ni bimetallic deposits prepared by galvanic replacement | |
| US5536379A (en) | Gas diffusion electrode | |
| EP2151004A2 (en) | Electrochemical cells and methods for generating fuel | |
| WO2010094113A1 (en) | Ammonia electrolyzer | |
| Ding et al. | Efficient integrated electrode enables high-current operation and excellent stability for green hydrogen production | |
| Ababao et al. | Recent advances in catalyst materials for PEM water electrolysis | |
| He et al. | Synthesis and characterization of Pt-Ti4O7 microelectrode arrays | |
| Zhao et al. | High crystallinity Sn crystals on Ni foam: an ideal bimetallic catalyst for the electroreduction of carbon dioxide to syngas | |
| JP7659138B1 (en) | Electrode containing oxygen evolution electrode catalyst | |
| Holze et al. | Double-layer capacity measurements as a method to characterize porous fuel cell electrodes | |
| WO2021193467A1 (en) | Manganese-iridium complex oxide for water decomposition catalyst, manganese-iridium complex oxide electrode material, and production methods therefor | |
| US4279713A (en) | Method of catalyzing the evolution of gaseous hydrogen | |
| Li et al. | Promoting the electrochemical reduction of carbon dioxide by a specially designed biomimetic electrochemical cell | |
| US8449739B2 (en) | Metal-coated carbon surfaces for use in fuel cells |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |