Process for selective, partial, substantially solvent-free, oxidation of methane to methanol and/or a methanol derivative with a heterogeneous catalyst and sulfur trioxide
The present invention relates to selective partial oxidation of methane in the absence of a solvent such as sulfuric acid or oleum.
1. A process for selective, partial oxidization of methane, the process being a substantially solvent-free process that comprises placing sulfur trioxide and gaseous methane in operative contact with a solid, heterogenous, acidic catalyst material, wherein the solid, heterogenous, acidic catalyst material is a superacid catalyst selected from a perfluorinated organo-sulfonic acid polymer, a composite of a perfluorinated organo-sulfonic acid polymer and a porous inorganic support, and a supported catalyst, the supported catalyst comprising at least one transition metal selected from a group consisting of palladium, vanadium and cerium on a composite of a perfluorinated organo-sulfonic acid polymer and a porous inorganic support, the contact occurring at a combination of temperature, methane pressure and for a length of time sufficient to convert at least a portion of non-gaseous forms of such sulfur trioxide to gaseous sulfur trioxide and selectively and partially oxidize at least a portion of the methane to at least one partial oxidation product selected from a group consisting of methanol and sulfate esters of methanol, the temperature being less than a temperature at which the solid, acidic catalyst material becomes unstable.
2. The process of claim 1 , wherein the contact occurs at a temperature of no more than about 230 ° C.
3. The process of claim 1 , wherein the length of time is less than a time sufficient to effect a substantially complete conversion of methane to its full oxidation products, carbon monoxide and carbon dioxide.
4. The process of claim 3 , wherein the length of time is within a range of from greater than 0.5 minute to less than or equal to 100 hours.
5. The process of claim 1 , wherein the methane pressure, measured at a temperature of 150° C., lies within a range of from 25 psig (170 kilopascals KPa to 2000 psig (13,790 KPa).
6. The process of claim 1 , wherein the transition metal of the supported catalyst is palladium.
7. The process of claim 6 wherein the supported catalyst has a palladium metal loading within a range of from greater than one percent by weight to less than or equal to four percent by weight, each percent by weight being based upon total supported catalyst weight.
8. The process of claim 1 , wherein the porous inorganic support comprises an oxide of a metal selected from silicon, aluminum, magnesium, titanium, zirconium and mixtures thereof.