Shape Selectivity in Methane Dehydroaromatization Over Mo/MCM-22 Catalysts During a Lifetime Experiment

Investigation of the stability of Zn-based HZSM-5 catalysts for methane dehydroaromatization

“…The high peak area and the peak broadening for the sample with no CO 2 addition indicated a large amount of carbon was formed, as well as the presence of different types of carbon on the spent catalyst surface. The fast ramping rate used during the TPO experiments could possibly cause overlap of the oxidation temperature peaks from different carbon types on the catalyst surface [14,62,70].…”

“…Many researchers have focused on finding ways to improve catalyst performance and reduce deactivation from coke. These approaches include modifying the surface of the zeolite support [6][7][8], adding promoters [9][10][11][12], adding trace amounts of oxidants [13][14][15], periodic methane/H 2 switching [13,16], optimizing the number and density of acid sites on HZSM-5 by changing the silica to alumina ratio (SAR) [17], and shifting the reaction equilibrium by removing hydrogen from the reaction using membrane reactors [18,19]. Nevertheless, the search for a more robust catalyst is still required.…”

On the deactivation of Mo/HZSM-5 in the methane dehydroaromatization reaction

“…Several studies have attempted to elucidate the reasons for the rapid deactivation of Mo/HZSM-5 catalysts during the MDA reaction [7][8][9][10][11][12][13][14][15][16][17]. Extensive formation of polyaromatics hydrocarbon carbon deposits was identified as the main reason for catalyst deactivation.…”

CO2 addition on the non-oxidative dehydro-aromatization of methane over MoMCM-22

“…To minimize this effect, a great number of studies have been done with different transition metals [3,[5][6][7][8][9] and different zeolites [9][10][11][12][13][14], searching for a selective catalyst for aromatics (especially benzene) but more stable than HZSM-5. One of the most promising zeolites seems to be HMCM-22 which showed a moderate deactivation even after 24 h TOS [10,11,15,16]. Some other studies tried to reduce the observed MoZSM-5 deactivation by the introduction of other gases along with methane, such as CO or CO 2 [5,16,17], H 2 [9,[17][18][19], NO [20] and O 2 [20].…”

“…One of the most promising zeolites seems to be HMCM-22 which showed a moderate deactivation even after 24 h TOS [10,11,15,16]. Some other studies tried to reduce the observed MoZSM-5 deactivation by the introduction of other gases along with methane, such as CO or CO 2 [5,16,17], H 2 [9,[17][18][19], NO [20] and O 2 [20].…”