Process analysis of heterogeneous catalytic reactions such as lignin depolymerization is essential to understand the reaction mechanism at the molecular level, but it is always challenging due to harsh conditions. Herein, we report an operando process analysis strategy by combining a microbatch reactor with highresolution mass spectrometry (MS) via a reactor-integrated electrospray ionization (R-ESI) technique. R-ESI-MS expands the applications of traditional in situ MS to a heterogeneous and high-pressure liquid-phase system. With this strategy, we present the evolution of a series of monomers, dimers, and oligomers during lignin depolymerization under operando conditions (methanol solvent, 260 °C, ∼8 MPa), which is the first experimental elucidation of a progressive depolymerization pathway and evidence of repolymerization of active monomers. The proposed R-ESI-MS is crucial in probing depolymerization intermediates of lignin; it also provides a flexible strategy for process analysis of heterogeneous catalytic reactions under operando conditions.

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Understanding the combustion behaviors of solid propellant with different levels of strains is of practical interest. In this work, an experimental study of the effects of static and dynamic strains on the burning rate, temperature, CO, and C O 2 formation of aluminized ammonium perchlorate (AP)-hydroxyl terminated poly-butadiene (HTPB) propellant combustion was presented at initial pressures of 0.1 MPa, 0.2 MPa, and 0.5 MPa. The strains were being applied onto solid propellant by exerting static and cyclic loadings. The propellant burning rate was acquired by a 4 kHz high-speed photography system, and the combustion temperature, CO, and C O 2 column densities were measured at 10 kHz through laser absorption spectroscopy (LAS). At atmospheric pressure, it was demonstrated that the propellant burning rate increased with tensile stress and decreased with compressive stress. The measured flame temperature showed a similar correlation with strains as compared to the propellant burning rate. At elevated pressures, the increase of the propellant burning rate due to tensile stress was more evident, while the difference in combustion temperatures was less significant. For the cyclic strain condition, the variations of the measured C O 2 and CO column densities were consistent with the static strain condition.