Zeolites are effective catalysts for hydrodeoxygenation of lignocellulosic biomass to high value hydrocarbons in a process called catalytic fast pyrolysis (CFP). The addition of ca. 1 % wt. Fe into zeolites produces an improvement in selectivity for benzene, toluene and xylene (BTX). Catalyst development for CFP requires the identification of deactivation mechanisms. We have synthesised two zeolite frameworks, Fe/ZSM-11 and Fe/ZSM-5, with similar Si:Al ratios and Fe concentrations, that display remarkably different deactivation mechanisms. Our previous experiment at ESRF ID20 (CH6840) has shown that a combination of X-ray Raman Spectroscopy (XRS) and Emission Spectroscopy (XES) can show key differences in coke speciation and formation. To continue this work, we propose to perform operando XRS-XES to simultaneously measure the C K-edge and the Fe Kβ emission line to probe Fe/ZSM-5 and Fe/ZSM-11 CFP hydrocarbon pool chemistry.