Infrared Spectroscopic Evidence of WS2 Morphology Change With Citric Acid Addition and Sulfidation Temperature

MS 2 morphology is strongly influenced by several parameters including the addition of a chelating agent and sulfidation temperature. In this work, we report use citric acid as in order to prepare series WS /Al O 3 catalysts that were submitted at temperatures. The effect these two slabs was explored means CO adsorption low temperature followed IR spectroscopy (IR/CO) later confirmed High-Resolution Scanning Transmission Electron Microscopy coupled with High Angular Annular Dark Field detector (HR STEM - HAADF). This allowed depict calculating M-edge/S-edge site ratio. preparation stage favors increase S-edge concentration whereas it keeps M-edge sites: according IR/CO, an increasing amount acid, progressively changes from slightly truncated triangle exhibiting predominantly M edges hexagon both edge S edge. addition, HR STEM-HAADF demonstrated impregnation step W considerably reduces size nanoparticles their dispersion degree. plates on activated catalyst typical range (573–673 K) detected be exposing S-edge. Furthermore, IR/CO results indicate degree truncation (ratio S-edge/M-edge) gradually rises However, most determining factor for modification turns out presence not change (i.e., S-edge/M-edge ratio) key catalytic performance, since show different reactivity hydrodesulfurization (HDS) reactions. Notably, also found only improves activity but stability catalysts, giving best performance concentrations higher than (CA/W = 1).