February 2, 2015
[We welcome our newest Patent Watch contributor, Steven Slome of Nexant (White Plains, NY)—Ed.]
These catalysts promote the oxidative coupling of methane to ethylene. A successful catalyst for converting methane to ethylene via oxidative coupling of methane (OCM) is to industrial chemical catalysis what the giant squid is to marine biology. Although we know that it is possible (or in the case of the giant squid, that it exists), producing a viable catalyst (like capturing or photographing a live giant squid) has been beyond our reach—until now.
OCM is seen as a way to produce liquids from gas, a so-called gas-to-liquids (GTL) technology. Unlike the conventional technologies for GTL, however, OCM would not require the syngas production and Fisher–Tropsch reaction sections that make GTL plants capital-intensive. Ethylene produced via OCM could be used to produce gasoline or jet fuel by using well-known industrial catalysts (e.g., zeolite ZSM-5 for gasoline or oligomerization catalysts for jet fuel).
OCM was discovered in the 1980s, but because methane is significantly less reactive than almost all of the conversion products and intermediates, the development of a working catalyst has failed. Many attempts to produce ethylene via OCM resulted in the reaction continuing past ethylene and eventually producing carbon dioxide and water.
In this patent application, W. P. Schammel and co-inventors claim heterogeneous metal-oxide catalysts that contain various dopants. The catalysts are useful in a variety of reactions, including OCM for producing ethylene and ethane.
Although the inventors focus on the OCM reaction, they claim utility for other reactions such as oxidative dehydrogenation of alkanes to the corresponding alkenes (e.g., propane to propylene or butanes to butenes), selective oxidation of saturated and unsaturated hydrocarbons, carbon monoxide oxidation, dry reforming of methane, selective oxidation of aromatics, the Fischer–Tropsch reaction, hydrocarbon cracking, and other important industrial reactions.
The patent application includes several examples of OCM catalysts that consist of
- a mixed manganese–tungsten oxide,
- a sodium dopant, and
- at least one other doping element from periodic table groups 2, 4–6, or 8–15; a lanthanide; or combinations of these metals.
Methane conversions are >20% at 750 ºC, with a selectivity to C2s (ethane and ethylene) of >50%. (Siluria Technologies [San Francisco]. US Pat. Appl. 20140274671, Sept. 18, 2014; Steven R. Slome)
View patent information from CAplus(SM) database.