Direct production of hydrogen and aromatics from methane or natural gas: Review of recent U.S. patents

Since the year 2000, the United States Patent and Trademark Office (USPTO) has granted a dozen patents for inventions related to methane dehydroaromatization processes. One of them was granted to UOP LLC (Des Plaines). It relates to a catalyst composition and preparation method. Two patents were granted to Conoco Phillips Company (Houston, TX). One was aimed at securing a process and operating conditions for methane aromatization. The other was aimed at securing a process that may be integrated with separation of wellhead fluids and blending of the aromatics produced from the gas with the crude. Nine patents were granted to ExxonMobil Chemical Patents Inc. (Houston, TX). Most of these were aimed at securing a dehydroaromatization process where methane-containing feedstock moves counter currently to a particulate catalyst. The coked catalyst is heated or regenerated either in the reactor, by cyclic operation, or in annex equipment, and returned to the reactor. The reactor effluent stream may be separated in its main components and used or recycled as needed. A brief summary of those inventions is presented in this review.