Patent Application: US-201313840831-A

Abstract:
a composition for oxidizing dimethyl ether includes an alloy supported on carbon , the alloy being of platinum , ruthenium , and palladium . a process for oxidizing dimethyl ether involves exposing dimethyl ether to a carbon - supported alloy of platinum , ruthenium , and palladium under conditions sufficient to electrochemically oxidize the dimethyl ether .

Description:
the invention relates to a composition and process for catalytic oxidation of dimethyl ether . embodiment compositions include a support material and a plurality of metals on the support material . in an embodiment of the composition for catalytic oxidation of dimethyl ether , the support material is carbon . in an embodiment of the composition for catalytic oxidation of dimethyl ether , the plurality of metals is a combination of platinum , ruthenium , and palladium . the combination is an alloy of these metals . in an embodiment for the catalytic oxidation of dimethyl ether , the composition is pt 60 ru 15 pd 26 supported on carbon . the invention was demonstrated by performing oxidations of dimethyl ether using an embodiment composition . benefits of the embodiment composition were demonstrated by experimental results comparing electrooxidation reactions using the embodiment composition with results using a commercially available catalyst that is considered to be a state - of - the - art catalyst for the oxidation of methanol . the embodiment composition pt 60 ru 15 pd 26 supported on carbon was synthesized by the polyol method . a variety of precursor materials including h 2 ptcl 6 · 6h 2 o , rucl 3 and pdcl 2 were used for the synthesis . in an embodiment , vulcan xc - 72 carbon black ( cabot corporation ) was used as the catalyst support . in an embodiment synthesis , 0 . 69 grams ( g ) h 2 ptcl 6 · 6h 2 o , 0 . 321 g rucl 3 and 0 . 053 g pdcl 2 were added to ethylene glycol solvent to form a brown solution . the brown solution had a metal concentration of about 2 mg metal per milliliter of solvent . the ph of the brown solution was adjusted by adding sodium hydroxide in deionized water until the ph was above a ph of 13 . after adjusting the ph , the resulting solution was heated to 170 ° c . and kept at this temperature for 3 hours . the result was a brown - black sol . at this time , 0 . 1 g xc - 72 carbon black was added to the brown - black sol and stirred for half an hour . the resulting mixture was cooled to room temperature and dilute hydrochloric acid was added to the mixture in order to adjust the ph to a value below 3 . the mixture was stirred for 12 hours to settle the nanoparticles of the mixture , which were then filtered and dried at 80 ° c . for 8 hours . the product after this drying was an embodiment composition of pt 60 ru 15 pd 25 supported on carbon . fig1 provides linear sweep voltammograms of current density in units of milliamperes per square centimeter ( ma / cm 2 ) versus potential in units of volts ( v ) versus rhe that compare the behavior of embodiment composition of pt 60 ru 15 pd 26 supported on carbon ( c ) with the behavior of a state - of - the - art catalyst . fig1 summarizes half - cell measurements that indicate that the specific activity of dme electrooxidation measured with the embodiment ternary composition pt 60 ru 15 pd 25 supported on carbon ( 24 % metal loading ), whose synthesis is described above , is higher than that of the state - of - the - art catalyst for methanol oxidation , which is prior art catalyst pt 50 ru 50 supported on carbon ( hispec ® 12100 , 75 % metal loading ). as fig1 shows , the onset potential of dme oxidation is by about 50 mv lower with the embodiment catalyst than with hispec ® 12100 ( 0 . 38 v vs . 0 . 43 v ). furthermore , the peak current of dme oxidation measured on the embodiment catalyst is larger than that on hispec ® 12100 for the same catalyst loading . fig2 provides a comparison of x - ray diffraction ( xrd ) patterns of two commercially available catalysts with the xrd pattern of an embodiment composition of pt 60 ru 15 pd 26 supported on carbon . the x - ray diffraction ( xrd ) patterns of fig2 confirm the alloy formation of the product embodiment composition pt 60 ru 15 pd 25 on carbon , as indicated by the ( 111 ) peak shift relative to pt . in summary , experimental data suggest that carbon - supported ternary metal compositions of pt , ru , and pd offer a performance advantage compared to carbon - supported binary metal compositions of pt and ru . without wishing to be bound by any particular theory or explanation , the performance advantage for oxidation of dimethyl ether may be due to an activating property of pd in the embodiment ternary alloy that facilitates c — o bond cleavage . although the present invention has been described with reference to specific details , it is not intended that such details should be regarded as limitations upon the scope of the invention , except as and to the extent that they are included in the accompanying claims . 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