Three recurring hypotheses are often used to explain the effect of non‐thermal plasmas (NTPs) on NTP catalytic hybrid reactions; namely, modification or heating of the catalyst or creation of new reaction pathways by plasma‐produced species. NTP‐assisted methane (CH4) oxidation over Pd/Al2O3 was investigated by direct monitoring of the X‐ray absorption fine structure of the catalyst, coupled with end‐of‐pipe mass spectrometry. This in situ study revealed that the catalyst did not undergo any significant structural changes under NTP conditions. However, the NTP did lead to an increase in the temperature of the Pd nanoparticles; although this temperature rise was insufficient to activate the thermal CH4 oxidation reaction. The contribution of a lower activation barrier alternative reaction pathway involving the formation of CH3(g) from electron impact reactions is proposed.

Three recurring hypotheses are often used to explain the effect of non-thermal plasmas (NTPs) on NTP catalytic hybrid reactions;n amely,m odification or heating of the catalyst or creation of new reaction pathwaysb yp lasmaproduced species.NTP-assisted methane (CH 4 )oxidation over Pd/Al 2 O 3 was investigated by direct monitoring of the X-ray absorption fine structure of the catalyst, coupled with end-ofpipe mass spectrometry.T his in situ study revealed that the catalyst did not undergo any significant structural changes under NTP conditions.H owever,t he NTP did lead to an increase in the temperature of the Pd nanoparticles;a lthough this temperature rise was insufficient to activate the thermal CH 4 oxidation reaction. The contribution of alower activation barrier alternative reaction pathway involving the formation of CH 3 (g) from electron impact reactions is proposed.