Selective Ring-Shift Isomerization in Hydroconversion of Fluorene over Supported Platinum Catalysts

Hydroconversion of fluorene has been conducted over the zeolites and silica–alumina-supported platinum catalysts. The hydrogenation of aromatic rings, the hydroisomerization of the cycloalkanes, and the cracking reaction over the Pt/Y zeolite catalysts are studied to give a detailed hydroconversion reaction network of fluorene through conversion of the synthesized intermediates. Compared to the β-zeolites and silica–alumina supports used, the dispersed platinum catalysts on the Y-zeolites with unique cage structure and acidic properties selectively catalyze the ring-shift isomerization of perhydrofluorene with high yields of the dodecahydrocyclopenta­[a]­naphthalene and dodecahydrophenalene. Such hydroisomerization reaction is enhanced above 250 °C, while more cleavage of carbon–carbon bond occurs at higher temperatures (280–290 °C) which lead to the great production of single-ring cycloalkanes and more loss in carbons. In the comparative study of the support effect, an examination of the product yields indicates that mild acidity and unique zeolitic structure of Y-zeolites show a major contribution to the selective ring-shift isomerization of saturated aromatic rings. In addition, the generation of mesopores in the Y-zeolite crystals by postsynthesis alkaline treatment facilitates the mass transfer of compounds and provides an improved yield of isomers

pH-Response Mechanism of <i>p</i>‑Aminobenzenethiol on Ag Nanoparticles Revealed By Two-Dimensional Correlation Surface-Enhanced Raman Scattering Spectroscopy

The existence of pH-dependent surface-enhanced Raman scattering (SERS) of <i>p</i>-aminobenzenethiol (PATP) on Ag nanoparticles has been confirmed by numerous studies, but its mechanism still remains to be clarified. Discussion of the mechanism is at a standstill because of the lack of a systematic investigation of the process behind the pH-induced variation of the PATP behavior. Two-dimensional correlation spectroscopy is one of the most powerful and versatile spectral analysis methods for investigating perturbation-induced variations in dynamic data. Herein, we have analyzed the pH-dependent behavior of PATP using a static buffer solution with pH ranging from 3.0 to 2.0. The order of the variations in the different vibrational intensities was carefully investigated based on 2D correlation SERS spectroscopy. These results have demonstrated that the very first step of the pH-response process involves protonation of the amine group. The pH-response mechanism revealed is an important new component to our understanding of the origin of the b₂-type bands of PATP

Additional file 1 of Choroid plexus enlargement in amyotrophic lateral sclerosis patients and its correlation with clinical disability and blood-CSF barrier permeability

Supplementary Material