Selective oxidation of methane to benzene over K2MoO4/ZSM-5 catalysts

Direct conversion of methane under nonoxidative conditions

“…Solymosi and co-workers [40][41][42] and Lunsford and coworkers [43,44] characterized the Mo/HZSM-5 catalyst by means of XPS and found that during the initial induction period, the original Mo 6+ ions in the zeolite were reduced by CH 4 to Mo 2 C, accompanied by the depositing of carbonaceous cokes. They suggested that Mo 2 C provides active sites for C 2 H 4 formation from CH 4 , while the acidic sites catalyze the subsequent conversion to C 6 H 6 .…”

Methane dehydroaromatization over Mo/HZSM-5 catalysts: The reactivity of MoCx species formed from MoOx associated and non-associated with Brönsted acid sites

“…10% and a selectivity to aromatics of ca. 70-80% at 973 K and a methane space velocity of around 1500 ml/g h [6][7][8][9][10][11][12][13]. It is well accepted that the Mo/HZSM-5 is a bifunctional catalyst.…”

“…The MoC x species are created via the reduction of MoO 3 by CH 4 in the early stage of the reaction and are regarded as active sites responsible for methane dehydrogenation and oligomerization into C 2 H y species (y < 4). Meanwhile, the Brönsted acid sites of the HZSM-5 zeolite are responsible for aromatization of the C 2 species [7][8][9][10][11][12][13]. Since either ethylene or ethane aromatization proceeds easily in the temperature range 573-873 K on HZSM-5 or transition metal (Zn, and/or Ga) modified HZSM-5 [14][15][16][17][18][19], such a bifunctional description of the Mo/HZSM-5 catalysts also suggests that methane dehydrogenation and However, more detailed descriptions of the bifunctionality of the Mo/HZSM-5 catalyst are missing, or still under debate.…”

Infrared study of the adsorption of CO and CH3 on silica-supported MoO3 and Mo2C catalysts

“…Further studies, however, revealed that MoO 3 is transformed into Mo 2 C in the high-temperature interaction of CH 4 with MoO 3 , and the Mo 2 C formed is considered to be the active site for the production of CH 3 and CH 2 fragments from methane [13][14][15][16].…”

“…A new catalytic application of molybdenum carbide has recently been established in the non-oxidative catalytic transformation of methane: as regards the formation of benzene in this reaction, MoO 3 /ZSM-5 proved to be the best catalyst [10][11][12][13][14][15][16], but MoO 3 /SiO 2 (even MoO 3 /Al 2 O 3 ) exhibited also a reasonable activity for methane-benzene conversion [12]. Further studies, however, revealed that MoO 3 is transformed into Mo 2 C in the high-temperature interaction of CH 4 with MoO 3 , and the Mo 2 C formed is considered to be the active site for the production of CH 3 and CH 2 fragments from methane [13][14][15][16].…”