Preparation of hierarchical structure of Y zeolite with ultrasonic-assisted alkaline treatment method used in catalytic cracking of middle distillate cut: The effect of irradiation time

Beneficial use of ultrasound irradiation in synthesis of beta–clinoptilolite composite used in heavy oil upgrading process

“…High mesoporous volume and external surface area of these samples leads to unlimited mass transfer and reduces pore blockage due to the coke deposition. These results is compatible with results of Oruji et al 43 which concluded that catalysts with higher mesopore volumes had higher life times. Amount of liquid production on Beta/CLT and Beta/AT-CLT has reached to an approximately constant value aer 270 minutes, which could be due to the lower mesoporous volume of these samples.…”

“…57 Therefore, gas production decreases aer a certain time on stream, which means gradual increment of liquid product yield occurs. 43 Finally, gas or liquid product yield reaches a constant value with no further changes, which means deactivation of the catalyst has happened. Ascending trend of liquid product yield over different prepared samples in 300 minutes time on stream is shown in Fig.…”

“…Silicon extraction from zeolite structure takes place during alkaline treatment of a zeolite as have been revealed numerously in literature so far, which in turn results in a more open structure and mesoporosity. [42][43][44] The OH À present in alkali solution attacks the zeolite structure but since clinoptilolite is negatively charged and silicon atoms are preserved with neighboring four ligand Al atoms, framework damage does not occur and selective dissolution of silicon takes place, 17 therefore, only slight decrease in crystallinity is observed. Calculated relative crystallinities are presented in Table 2. XRD pattern of Beta sample presents typical diffraction pattern of zeolite beta with detected peaks at 2q ¼ 7.5 and 22.4 (JCPDS 48-0074).…”

Acid Properties of Hierarchical Zeolites Y

“…On the contrary, Oruji et al [57] reported a small increase of acidity (measured by TPD-NH 3 ) in zeolite Y which was desilicated without previous dealumination. Desilication was done with NaOH without and with ultrasonication.…”

“…Many data on the synthesis of mesoporous zeolites, their properties and catalytic applications were presented in the monograph of J. Garcia-Martinez and Kunhao Li [49]. Desilication of zeolite Y was much less frequently studied [35,[50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66].…”