7372-88-5Relevant articles and documents
Synthesis of NiMo Catalysts Supported on Gallium-Containing Mesoporous y Zeolites with Different Gallium Contents and Their High Activities in the Hydrodesulfurization of 4,6-Dimethyldibenzothiophene
Zhou, Wenwu,Liu, Meifang,Zhang, Qing,Wei, Qiang,Ding, Sijia,Zhou, Yasong
, p. 7665 - 7679 (2017/11/10)
Mesoporous MY-xGa zeolites exhibiting both crystallized pore walls and narrowly dispersed mesopores with different Ga content were successfully synthesized. The synthesized samples were characterized by XRD, N2 adsorption desorption isotherms, SEM, TEM, XPS, FTIR, 29Si MAS NMR, 71Ga MAS NMR, and Py-FTIR methods. The results show that the synthesized samples exhibit unique open channel like mesopore systems and outstanding crystallite natures; no nonframework Ga species were observed over the MY-xGa series samples, and their acidic properties can be modulated by varying the Ga/Al ratio in the initial synthesis gel. The corresponding NiMo/HMY-xGa catalysts were prepared via the incipient wetness coimpregnation method; the morphologies of the sulfide catalysts were characterized by HRTEM, and the covalent states of the active metals were characterized by XPS. The catalytic activities of the investigated catalysts for the 4,6-DMDBT HDS reaction were assessed, and the collected products were analyzed by GC and GC-MS methods. The catalyst NiMo/HMY-0.5Ga showed the highest catalytic activity due to the synergistic effect of modulated acidic properties, excellent morphology, highest sulfidation degree, and proper proportion of NiMoS phase. More importantly, 4-MDBT, DBT, and BP were observed and identified as the products of the 4,6-DMDBT HDS reaction, designated as the demethylation pathway (DM) for the 4,6-DMDBT HDS reaction. Finally, a reaction network including DDS, HYD, ISO, and DM pathways for the 4,6-DMDBT HDS reaction over catalyst NiMo/HMY-0.5Ga was proposed.
Formation of dibenzofurans by flash vacuum pyrolysis of aryl 2-(allyloxy)benzoates and related reactions
Black, Michael,Cadogan,McNab, Hamish
experimental part, p. 2961 - 2967 (2010/09/06)
Flash vacuum pyrolysis (FVP) of aryl 2-(allyloxy)benzoates 5 and of the corresponding aryl 2-(allylthio)benzoates 6 at 650°C, gives dibenzofurans 19 and dibenzothiophenes 20, respectively. The mechanism involves generation of phenoxyl (or thiophenoxyl) radicals by homolysis of the O-allyl (or S-allyl) bond, followed by ipso attack at the ester group, loss of CO2 and cyclisation of the resulting aryl radical. Synthetically, the procedure works well for p-substituted substrates, which lead to 2-substituted dibenzofurans 19b-f (73-90%) and dibenzothiophenes 20b-c (90-94%). Little selectivity is shown in the cyclisation of m-substituted substrates and competing interactions of the radical with the substituent - and ipso-attack - complicate the pyrolyses of o-substituted substrates. FVP of related radical precursors including 2-(allyloxy)phenyl benzoates 43 gave no dibenzofurans, whereas 2-(allyloxy-5-methyl)azobenzene 44 gave a much reduced yield. No carbazoles were obtained by FVP of 4-methylphenyl 2-(allylamino)benzoate 42.
Gas phase generation and cyclisation reactions of some o-substituted phenyl radicals
Cadogan,Hutchison,McNab
, p. 7747 - 7762 (2007/10/02)
Flash vacuum pyrolysis of the allyl esters 2 (X=O, S, CH2, CO) at 900°C (10-2 Torr) gives dibenzofurans, dibenzothiophenes, fluorenes, and fluorenones respectively as the major products. The mechanism involves the phenyl radical intermediates 1 which equilibrate by intramolecular hydrogen transfer via six-membered transition states, prior to cyclisation.
