Formation Energetics and Guest—Host Interactions of Molybdenum Carbide Confined in Zeolite Y

2021 ◽  
Vol 60 (38) ◽  
pp. 13991-14003
Author(s):  
Xianghui Zhang ◽  
Margaret E. Reece ◽  
Cody B. Cockreham ◽  
Hui Sun ◽  
Baodong Wang ◽  
...  
Keyword(s):  
Molybdenum Carbide ◽  
Zeolite Y ◽  
Host Interactions

scholarly journals Thermodynamics of Molybdenum Trioxide (MoO3) Encapsulated in Zeolite Y

2021 ◽  
Author(s):  
Xianghui Zhang ◽  
Andrew Strzelecki ◽  
Cody Cockreham ◽  
Vitaliy Goncharov ◽  
Houqian Li ◽  
...  
Keyword(s):  
Molybdenum Trioxide ◽  
Zeolite Y ◽  
Formation Enthalpy ◽  
Solution Calorimetry ◽  
Metal Species ◽  
Enthalpies Of Formation ◽  
Host Interactions ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide

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 (MoO) 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 MoO/FAU is less endothermic than corresponding zeolite Y, suggesting enhanced thermodynamic stability. As Si/Al ratio increases, the enthalpies of formation of MoO/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 TO (Si/Al = 45.6). Coupled with spectroscopic, structural and morphological characterizations, we revealed intricate energetics of MoO – zeolite Y guest – host interactions likely determined by the subtle redox and/or phase evolutions of encapsulated MoO.

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

2021 ◽  
Author(s):  
Xianghui Zhang ◽  
Su Ha ◽  
Di Wu
Keyword(s):  
High Activity ◽  
Steam Reforming ◽  
Large Scale ◽  
Molybdenum Carbide ◽  
Ostwald Ripening ◽  
Zeolite Y ◽  
Metallic Nickel ◽  
Transition Metal Carbide ◽  
Methane Steam Reforming ◽  
Methane Steam

Methane steam reforming (MSR) reaction is a mature industrial process that has been applied for large-scale hydrogen production. Here, we report the synthesis and characterization, reaction kinetics, and deactivation mechanism of a series of catalysts with metallic nickel (Ni) clusters and molybdenum carbide (Mo2C) particles supported on zeolite Y (Ni-Mo2C/FAU) in MSR reaction at 850 oC. Despite low Ni loading less than 2.4 wt%, MSR on Ni-Mo2C/FAU exhibits high activity and stability, yet deactivation of Ni-FAU (the sample without Mo2C) is significant. Further investigations elucidate that the catalyst deactivation is caused by Ni particle sintering via Ostwald ripening instead of coking, and steam induces hydroxylated Ni surface that accelerates sintering. Moreover, encapsulated Mo2C boosts the activity and stability of Ni on zeolite Y by enhancing CH4 activation rather than activating H2O. The interplays among Mo2C and Ni particles dynamically balance the carbon formation and consumption rates, and inhibit Ni sintering. This study enables insights into an alternative design principle of transition metal carbide – Ni catalysts with high activity and stability for effective MSR by tuning the compositional, structural, and interfacial factors.

A study of nanostructure assemblies and guest-host interactions in sodium zeolite-Y using23Na double-rotation NMR

1991 ◽  
Vol 2 (4) ◽  
pp. 182-186 ◽  
Author(s):  
R Jelinek ◽  
A Pines ◽  
S Ozkar ◽  
G A Ozin
Keyword(s):  
Zeolite Y ◽  
Host Interactions

scholarly journals Thermodynamics of Molybdenum Trioxide (MoO3) Encapsulated in Zeolite Y

2021 ◽  
Author(s):  
Xianghui Zhang ◽  
Vitaliy Goncharov ◽  
Cody Cockreham ◽  
Houqian Li ◽  
Junming Sun ◽  
...  
Keyword(s):  
Molybdenum Trioxide ◽  
Zeolite Y ◽  
Formation Enthalpy ◽  
Solution Calorimetry ◽  
Catalytic Performance ◽  
Metal Species ◽  
Enthalpies Of Formation ◽  
Host Interactions ◽  
Oxide Melt ◽  
High Temperature Oxide

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 MoO3 loading tends 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, and catalytic performance tests, we revealed intricate energetics of MoO3 – zeolite Y guest – host interactions and catalytic performance governed by the phase evolutions of encapsulated MoO3.

Double Rotation 23Na NMR Study of Guest-Host Interactions and Nanoscale Assemblies in Sodium Zeolite Y

1992 ◽  
Vol 277 ◽  
Author(s):  
R. Jelinek ◽  
S. Ozkar ◽  
G. A. Ozin
Keyword(s):  
Zeolite Y ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Molybdenum Hexacarbonyl ◽  
Guest Molecules ◽  
Host Interactions ◽  
Spin Lattice ◽  
Sodium Cations ◽  
Nmr Study ◽  
Relaxation Measurements

ABSTRACT23Na double rotation NMR (DOR) provides information on site-specific adsorption of guest molecules within the porous framework of sodium zeolite Y. Anchoring of molybdenum-hexacarbonyl to extraframework Na+ cations in particular locations within the large α-cavities is detected. Changes of the chemical environments of the Na+ cations are observed upon loading trimethylphosphine molecules. Spin-lattice relaxation measurements yield insight on dynamic aspects of the anchoring sodium cations.

scholarly journals Thermodynamics of Molybdenum Trioxide Encapsulated in Zeolite Y

2021 ◽  
Author(s):  
Xianghui Zhang ◽  
Andrew Strzelecki ◽  
Cody Cockreham ◽  
Vitaliy Goncharov ◽  
Houqian Li ◽  
...  
Keyword(s):  
Molybdenum Trioxide ◽  
Zeolite Y ◽  
Formation Enthalpy ◽  
Solution Calorimetry ◽  
Metal Species ◽  
Enthalpies Of Formation ◽  
Host Interactions ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide

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 (MoO) 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 MoO/FAU is less endothermic than corresponding zeolite Y, suggesting enhanced thermodynamic stability. As Si/Al ratio increases, the enthalpies of formation of MoO/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 TO (Si/Al = 45.6). Coupled with spectroscopic, structural and morphological characterizations, we revealed intricate energetics of MoO – zeolite Y guest – host interactions likely determined by the subtle redox and/or phase evolutions of encapsulated MoO.

Surface roughness measurements of vanadium-contaminated fluidized cracking catalysts by atomic force microscopy

1996 ◽  
Vol 54 ◽  
pp. 866-867
Author(s):  
H. Kinney ◽  
M.L. Occelli ◽  
S.A.C. Gould
Keyword(s):  
Surface Roughness ◽  
Zeolite Y ◽  
Atomic Level ◽  
Microporous Structure ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After ◽  
Roughness Measurements ◽  
Cracking Catalysts

For this study we have used a contact mode atomic force microscope (AFM) to study to topography of fluidized cracking catalysts (FCC), before and after contamination with 5% vanadium. We selected the AFM because of its ability to well characterize the surface roughness of materials down to the atomic level. It is believed that the cracking in the FCCs occurs mainly on the catalysts top 10-15 μm suggesting that the surface corrugation could play a key role in the FCCs microactivity properties. To test this hypothesis, we chose vanadium as a contaminate because this metal is capable of irreversibly destroying the FCC crystallinity as well as it microporous structure. In addition, we wanted to examine the extent to which steaming affects the vanadium contaminated FCC. Using the AFM, we measured the surface roughness of FCCs, before and after contamination and after steaming.We obtained our FCC (GRZ-1) from Davison. The FCC is generated so that it contains and estimated 35% rare earth exchaged zeolite Y, 50% kaolin and 15% binder.

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