Explaining the Process that Governs the Direct Conversion of Methane to Olefins Using Sulfur

Achievement date: 
2018
Outcome/accomplishment: 

The mechanism that controls processes for directly converting methane to olefins using sulfur was, for the first time, described by scientists at the Center for Innovative and Strategic Transformation of Alkane Resources (CISTAR), an NSF-funded Engineering Research Center (ERC) based at Purdue University.

Impact/benefits: 

For decades, an elusive goal for the petrochemical industry has been to use oxygen to directly convert natural gas, primarily methane, into olefins such as ethylene, the world’s largest commodity chemical. CISTAR scientists have explained how the use of a milder oxidant, sulfur, might produce more olefins and fewer, undesired side products.

Explanation/Background: 

Scientists in the 1980s identified the potential of using oxygen to convert liquid gas into ethylene, which is used in the manufacturing of products ranging from food packaging to liquid crystal displays. The direct conversion could prove much more efficient than the high heats now used to produce olefins from methane, a costly process the restricts the use of methane as a petrochemical feedstock. But the use of oxygen has remained a challenge due to the difficult activation of methane and rapid over-oxidation of olefins, and rapid catalyst deactivation.

Efforts have considered alternatives to oxygen, such as the use of sulfur, which lowers the thermodynamic driving force that produces undesired side products. The CISTAR explanation of this Soft Oxidative Coupling of Methane (SOCM) process provides understanding of undesirable carbon-disulfide formation and desirable ethylene. This research also provides insights into future catalysts designed for not only SOCM, but other systems involving the reaction of soft oxidants with hydrocarbons.