Thermodynamics of molybdenum trioxide encapsulated in zeolite Y

AbstractZeolites with encapsulated transition metal species are extensively applied in the chemical industry as heterogenous catalysts for favorable kinetic pathways. To elucidate the energetic insights into formation of subnano-sized molybdenum trioxide (MoO3) encapsulated/confined in zeolite Y (FAU) from constituent oxides, we performed a systematic experimental thermodynamic study using high-temperature oxide melt solution calorimetry as the major tool. Specifically, the formation enthalpy of each MoO3/FAU is less endothermic than corresponding zeolite Y, suggesting enhanced thermodynamic stability. As Si/Al ratio increases, the enthalpies of formation of MoO3/FAU with identical loading (5 Mo-wt%) tend to be less endothermic, ranging from 61.1  ± 1.8 (Si/Al = 2.9) to 32.8 ± 1.4 kJ/mol TO2 (Si/Al  = 45.6). Coupled with spectroscopic, structural and morphological characterizations, we revealed intricate energetics of MoO3–zeolite Y guest–host interactions determined by the Si/Al ratio and the subtle redox and/or local structural evolutions of encapsulated MoO3.

Source: AIChE Journal - October 17, 2021 Category: Science Authors: Xianghui Zhang, Andrew C. Strzelecki, Cody B. Cockreham, Vitaliy G. Goncharov, Houqian Li, Junming Sun, Hui Sun, Xiaofeng Guo, Hongwu Xu, Ha Su, Baodong Wang, Yong Wang, Di Wu Tags: FUTURES ISSUE: THERMODYNAMICS AND MOLECULAR ‐SCALE PHENOMENA Source Type: research