“…Channel exits are located on the side walls of MWW crystals, which means that a desorbing molecule has to diffuse along the whole crystal, thus the probability that it will encounter and readsorb on the subsequent acid centers depends on the concentration of the acid sites and should diminish with the increasing Si/Al. Such trend was also observed with other measurement methods [40,41].…”
A series of MWW-type zeolites of increasing Si/Al ratio were investigated with respect to their acidic properties. Concentration of the Brønsted acid centers located at the external crystal surface was invariant for the entire series. Ethanol conversion to ethyl-tert-butyl ether, proceeding only at the external surface, was also constant. The OH groups in MWW zeolites were found to be homogeneous with proton affinity value equal to 1142.7 kJ/mol.
“…Channel exits are located on the side walls of MWW crystals, which means that a desorbing molecule has to diffuse along the whole crystal, thus the probability that it will encounter and readsorb on the subsequent acid centers depends on the concentration of the acid sites and should diminish with the increasing Si/Al. Such trend was also observed with other measurement methods [40,41].…”
A series of MWW-type zeolites of increasing Si/Al ratio were investigated with respect to their acidic properties. Concentration of the Brønsted acid centers located at the external crystal surface was invariant for the entire series. Ethanol conversion to ethyl-tert-butyl ether, proceeding only at the external surface, was also constant. The OH groups in MWW zeolites were found to be homogeneous with proton affinity value equal to 1142.7 kJ/mol.
“…So it can be deduced that not all the Al atoms are incorporated the framework of MCM-22 zeolites during the synthesis process for MCM-22 with Si/Al = 15. The results are consistent with the literature [32].…”
Section: Characterization Of the Mcm-22 Zeolites With Differentsupporting
“…MCM-22 has attracted much attention for its prospects in many catalytic reactions and its potential for industrial application [17][18][19][20][21][22]. There are at least 8 unequivalent T-sites in the framework structure of this zeolite [17].…”
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