Thermodynamics of molybdenum trioxide encapsulated in zeolite Y

Abstract

Zeolites 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.

Elucidating the Role and Interplay of Nickel and Molybdenum Carbide Particles Supported on Zeolite Y in Methane-Steam Reforming

“…We also noticed that these Mo2C NPs are amorphous showing no XRD peak (Figure 1a). Such phenomenon was not seen in our earlier studies on confinement of MoO3 and Mo2C in zeolite HY, 30,31 in which the Mo species stay within the framework, but was observed in multiple studies on synthesis and applications of Mo oxides, carbides, and sulfides supported on zeolites. [32][33][34][35][36][37] The activation energies were derived and compared in the kinetic region (see Figure 4).…”

Elucidating the promoting role of Mo2C in methane activation using Ni-xMo2C/FAU to catalyze methane steam reforming

“…We also noticed that these Mo2C NPs are amorphous showing no XRD peak (Figure 1a). Such phenomenon was not seen in our earlier studies on confinement of MoO3 and Mo2C in zeolite HY, [30,31] in which the Mo species stay within the framework, but was observed in multiple studies on synthesis and applications of Mo oxides, carbides, and sulfides supported on zeolites. [32-37] The activation energies were derived and compared in the kinetic region (see Figure 4).…”

Hypervalent Iodine Mediated Synthesis of Thiosulfonates from Sulfonyl Hydrazides and Their Transformation into Symmetrical Disulfides

“…A plausible reaction mechanism is outlined in Scheme 5 , based on the control experiments and previous reports. 44 Initially, the reaction between p -toluenesulfonyl hydrazide ( 1a ) and PIDA results in the production of intermediate A , accompanied by the removal of AcOH. Subsequently, intermediate B is formed through the elimination of AcOH and iodobenzene (PhI) from A .…”