An Investigation Into the Upgrading Process of Lignin Model Dimer-Phenethyl Phenyl Ether byin situ2H NMR and GC-MS

A key challenge in studying the upgrading process for the thermochemical conversion of biomass, such as lignin, is to understand the underlying mechanisms of catalytic conversion at the atomic scale. In this study, a method combined within situ(2)H NMR and GC-MS was proposed for investigating the conversion of phenethyl phenyl ether (PPE) in the hydrotreating process, as catalyzed by Pd, Ru, and Pt loaded onto C or gamma-Al2O3. The results indicated that Pd/gamma-Al(2)O(3)prefers to produce more ether bond-cleaved products, while Pt prefers to produce more hydrogenation products from PPE. Furthermore, based on this new strategy, a possible reaction mechanism of PPE with Pd/gamma-Al(2)O(3)was presented from the atomic point of view, showing the potential of thisin situdetection method for reaction mechanism studies. Besides, mechanistic investigations by GC-MS were accomplished for the hydrothermal treatment of PPE for comparison with the new method. The results showed that thein situ(2)H NMR combined with GC-MS provided a deeper understanding of the catalytic mechanism compared to GC-MS alone.