Enhancement of the strong Brønsted acidity and mesoporosity: Zr4+ promoted framework modification of Zeolite Y

One-Step Synthesized Solid Acid Catalyst with High Zr Content for Efficient and Green PET Degradation in Supercritical CO2

“…The samples demonstrate maximum absorption peaks at 205–215 nm, and the intensity of these peaks amplifies as the Zr content increases. This absorption band at the mentioned position signifies the ligand-to-metal charge transfer from O 2– to the tetrahedral Zr 4+ ions in the zeolite framework . In ZrO 2 , the Zr–O–Zr bonding leads to the appearance of the maximum absorption peak at approximately 230 nm .…”

“…This absorption band at the mentioned position signifies the ligand-to-metal charge transfer from O 2− to the tetrahedral Zr 4+ ions in the zeolite framework. 19 In ZrO 2 , the Zr−O−Zr bonding leads to the appearance of the maximum absorption peak at approximately 230 nm. 40 The incorporation of Zr 4+ into the framework can be described as a process of dispersing a single atom, resulting in a shift of the Zr−O absorption band toward higher energy.…”

“…The simulation calculations of the proton affinity of BAS and LAS on zeolite revealed that BAS exhibits a higher proton affinity, thereby playing a more positive role during the reaction process. Due to the facile adjustment of the acidic strength and acid distribution through doping other elements into zeolite, − the incorporation of metal dopants at framework sites in zeolites holds significant implications for designing novel catalysts with tailored activity. − Zhou et al prepared zeolite catalysts loaded with different metals (Zr, Ga, Mo, Co) using impregnation method for propane dehydrogenation reaction. It was found that the total acid content and B/L ratio of the catalyst exhibited varying degrees of decrease after metal loading.…”

Bifunctional CaCO3/HY Catalyst in the Simultaneous Cracking-Deoxygenation of Palm Oil to Diesel-Range Hydrocarbons

“…According to Yi et al (2019), there were three kinds of adsorbed species on alkaline metal oxide basic sites through CO2-TPD, including unidentate carbonate forms on surface O 2− ions, bidentate carbonate forms on Lewis-acid-Brønsted-basic pairs (Ca 2+ -O 2− ), and bicarbonate species on weak basic sites. Concerning the cracking process, the Brønsted acid site is important according to Meng et al (2022) suggestion that the reaction conversion and product distribution of the cracking process may be controlled by adjusting the Brønsted acidity of zeolite HY. In general, a strong acid catalyst with a high concentration of Brønsted and/or Lewis acids sites of original or modified zeolite HY is needed for cracking hydrocarbon, while deoxygenation reaction pathway is tailored by strong basicity adjusted by CaCO3.…”