Electroless Plating in Microchannels

Abstract

Novel methods of electroless plating are described. Catalyst coatings can be applied within microchannel apparatus. Various reactions, including combustion and steam reforming, can be conducted over electroless catalyst coatings.

1 . A method of electroles sly depositing Rh, comprising:
 forming an Rh-containing aqueous solution comprising a Rh amine complex having a Rh content of at least 1 g/L;   wherein the Rh-containing aqueous solution is essentially free of chloride and nitrite;   contacting a support with the Rh-containing aqueous solution;   reacting the Rh-containing aqueous solution with a reducing agent; and   depositing Rh onto the support.   
     
     
         2 . The method of  claim 1  wherein the aqueous solution is formed by dissolving a solid compound having the stiochiometry Rh(NH 3 ) x (OH) 3 , where x is 3 to 6. 
     
     
         3 . The method of  claim 1  comprising forming, at room temperature, an Rh-containing aqueous solution comprising a Rh amine complex having a Rh content of at least 1 g/L. 
     
     
         4 . The method of  claim 1  wherein the aqueous solution comprising a Rh amine complex consisting essentially of Rh, NH 3 , and at least one of OH, and NO 3 . 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . Microchannel apparatus, comprising:
 a flow path comprising a microchannel;   an electrolessly-applied passivation coating on at least one wall defining the flow path;   a catalyst in the microchannel;
 wherein the catalyst and the electrolessly-applied passivation coating have different compositions; and 
 wherein the electrolessly-applied passivation coating comprises at least one element selected from the group consisting of: Pt, Cu, Au, Ag, Pd, Rh, Ru, Re, Zn, and combinations thereof. 
   
     
     
         8 . (canceled) 
     
     
         9 . The method of  claim 8  wherein the catalyst metal comprises Pt and wherein the oxidation comprises heating to a temperature of at least 500° C. in the presence of oxygen (O 2 ) and wherein the reduction comprises heating to a temperature of at least 500° C. in the presence of hydrogen (H 2 ), and further comprising at least two cycles of oxidation and reduction. 
     
     
         10 . (canceled) 
     
     
         11 - 13 . (canceled) 
     
     
         14 . A catalyst comprising Pt disposed on zirconia and further characterizable by an active stability such that, if tested at a temperature of 880° C. and exposed to a process stream made of steam and methane at a 3:1 ratio, 27 atm, and a contact time of 4.2 ms for about 165 hours without regeneration, exhibits a methane conversion of about 75%. 
     
     
         15 . The catalyst of  claim 14  wherein the zirconia consists essentially of pure zirconia. 
     
     
         16 . The catalyst of  claim 14  wherein the catalyst has a Pt loading of at least 0.6 mg/cm 2 . 
     
     
         17 . The catalyst of  claim 16  wherein the zirconia is disposed over an oxide coating on a microchannel wall. 
     
     
         18 . A method of methane steam reforming, comprising:
 passing steam and methane in contact with a catalyst comprising Pt disposed on zirconia for at least 165 continuous hours without regeneration, at a temperature of about 850 to 900° C., a contact time of 15 ms or less, and obtaining a methane conversion, after at least 165 hours, of at least 70%.   
     
     
         19 . (canceled) 
     
     
         20 . The method of  claim 18  wherein the contact time is 10 ms or less, and wherein the catalyst has a Pt loading of at least 0.6 mg/cm 2 .