Chain scission modification mode in plasma catalytic n-undecane decomposition: In situ probing of intermediates and reaction pathways

•Effect of Ag-O-Al entity on C11H24 activation was analyzed by C11H24-TPD and C11H24-P-TPD.•Different types of byproducts with different number of carbons were systematic studied by GC-MS.•The value of υasCH3/υasCH2 in processes of adsorption and reaction were analyzed by in situ DRIFTS.•Plasma-catalytic C11H24 degradation mechanism of chain scission and oxidation was put forward.