(257d) Shaped Catalysts for Oxidative Coupling of Methane

The oxidative coupling of methane (OCM) is a promising way to convert methane into more valuable C2 hydrocarbons. The catalytic reaction has been mainly studied with diluted methane concentration. In addition, most of the studies have focused on the characterization and testing on catalysts in powder form which relevancy is questionable since the importance of gas phase reaction and in particular pore volumes have been identified as key parameters which drive catalytic performances.

In this study, we investigate the OCM under more relevant industrial conditions, in terms of reactor pressure (up to 7 bars), biogas feedstock composition (undiluted feed gas composed with CO₂) and on shaped catalysts. The catalyst chosen for our study is the well-known MnNaW OCM catalyst which is promising in terms of good trade-off between conversion and C2 yield.

A shaping study was carried out by investigating key parameters including material supports and geometries, calcination temperature and active phase loading. The effects of pressure and temperature were also investigated. Typically, the temperature was varied from 700 to 900°C at 3 bars. For best catalysts the pressure was increased up to 7 bars. For qualifying the CO₂ content in a biogas feedstock, the inlet CO₂ content was increased up to 40 %. The results can be summarized:

• No performance impact in the presence of CO₂ even up to 40%vol
• Stable performances after 4 days of reactions with a temperature exploration up to 900°C
• Higher pressure and temperature lead to a higher activity
• Surprisingly C₂H₄ and CO selectivity are promoted with the pressure and the temperature

Promising results were obtained on supported catalysts in relevant OCM conditions with high CO₂ content in the feed. We will discuss catalyst characterization combined with kinetic modeling for the identifications of key catalyst parameters that drive activity and selectivity.