Increasing amounts of available petroleum feedstocks correspond to natural gas sources or other methane-containing sources. The increased availability of methane and/or small hydrocarbon petroleum sources can potentially have increased value if efficient methods can be identified for conversion to larger compounds.
One option for converting methane (and other small hydrocarbons) to other compounds is to reform the methane to form H2 and/or CO (i.e., synthesis gas). Both steam reforming and dry reforming are known, but each type of reforming poses a variety of challenges. In particular, both types of reforming processes are prone to formation of coke on the reforming catalyst. This is especially true when the natural gas feed contains elevated levels of CO2 and/or C2+ hydrocarbon molecules, such as ethane or propane. In such cases, conventional reforming processes employ additional gas separations processes to reduce the CO2 content to acceptable levels—about 18-20% for steam reforming processes and much lower, about 5%, for autothermal reforming processes—or a prereformer to convert C2+ hydrocarbons to carbon monoxide and hydrogen.
These pretreatments increases the capital and operating expenses of reformning processes. Moreover, natural gas streams with high amounts of CO2 and/or C2+ hydrocarbons are more likely to be used as low cost fuels rather than for the production of high margin products through their conversion into synthesis gas, and are thus cost suppressed.
U.S. Pat. No. 8,454,911 describes methods of using a reverse flow reactor for reforming of methane to form acetylene.
U.S. Pat. No. 7,217,303 describes methods for pressure swing reforming of a hydrocarbon fuel in the presence of steam to form hydrogen. The reforming step is described as having a peak temperature of 700° C. to 2000° C.
U.S. Pat. No. 7,815,873 describes methods for reforming of a hydrocarbon fuel in a reverse flow reactor configuration. The reforming step is described as having a temperature of at least 1000° C.