Lewis acidity and substituent effects influence aldehyde enolization and C–C coupling in beta zeolites

He, Wenlin; Potts, David S.; Zhang, Zhongyao; Liu, Bowei; Schuarca, Robson L.; Hwang, Son-Jong; Bond, Jesse Q.; Flaherty, David W.; Cybulskis, Viktor J.

doi:10.1016/j.jcat.2023.115105

Cited by 8 publications

(3 citation statements)

References 95 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…95 As shown in Fig. 7B, the peaks at ∼700 and ∼825 cm −1 are attributed to the BEA framework, 96 while the metal oxides such as HfO 2 , ZrO 2 and TiO 2 show peaks in the region of 600–800 cm −1 . The absence of peaks associated with metal oxides indicates that heteroatoms are highly dispersed and probably incorporated into the BEA framework.…”

Section: Lewis Acid Zeolitesmentioning

confidence: 95%

Heteroatom Lewis acid zeolites: synthesis, characterization and application in the conversion of biomass-derived oxygenates

Yang,

Ge,

Zhu

2024

Green Chem.

View full text Add to dashboard Cite

show abstract

Section: Lewis Acid Zeolitesmentioning

confidence: 95%

Heteroatom Lewis acid zeolites: synthesis, characterization and application in the conversion of biomass-derived oxygenates

Yang,

Ge,

Zhu

2024

Green Chem.

View full text Add to dashboard Cite

show abstract

“…Rational and isomorphous substitution to a crystalline catalyst is a common but very important strategy for regulating catalytic performance for particular applications by tuning the acidity/basicity, redox, or adsorption properties. , Typically, the strength or the number of acidic/basic centers on the catalyst surface can be modified by changing the type and/or concentration of dopant ions in the target catalyst. − For example, the incorporation of Ga 3+ into zeolite ZSM-22 can significantly reduce its Brønsted acidity because the acidity for the bridged hydroxyl of Ga–OH–Si is weaker than that of Si–OH–Al; consequently, the Ga 3+ -doped ZSM-22 (loaded with Pt) exhibits a higher selectivity in n -dodecane isomerization compared to the undoped ZSM-22 . LaFeO 3 doped with Al 3+ exhibits a better catalytic activity in methane partial oxidation than pristine LaFeO 3 because this size-mismatch substitution leads to reduced tilting of the FeO 6 octahedra, improves the Fe–O covalency, and reduces the formation energy of oxygen vacancies, which eventually enhances the oxygen exchange kinetics …”

mentioning

confidence: 99%

From Lewis Acid to Lewis Base by La³⁺-to-Y³⁺ Substitution in α-YB₅O₉: Local Structure Modification Induced Lewis Basicity

Yang,

Sun,

et al. 2024

J. Phys. Chem. Lett.

View full text Add to dashboard Cite

Different from the common perspective of average structure, we propose that the locally elongated metal−oxygen bonds induced by La 3+ -to-Y 3+ substitution to a Lewis acid α-YB 5 O 9 generate medium-strength basic sites. Experimentally, NH 3 -and CO 2 -TPD experiments prove that the La 3+ doping of α-Y 1−x La x B 5 O 9 (0 ≤ x ≤ 0.24) results in the emergence of new medium-strength basic sites and the increasing La 3+ concentration modifies the number, not the strength, of the acidic and basic sites. The catalytic IPA conversion exhibits a reversal of the product selectivity, i.e., from 93% of propylene for α-YB 5 O 9 to ∼90% of acetone for α-Y 0.76 La 0.24 B 5 O 9 , which means the La 3+ doping gradually turns the solid from a Lewis acid to a Lewis base. Besides, α-Y 0.76 RE 0.24 B 5 O 9 (RE = Ce, Eu, Gd, Tm) compounds were prepared to consolidate the above conjecture, where the acetone selectivity exhibits a linear dependence on the ionic radius (or electronegativity). This work suggests that the substitution-induced local structure change deserves more attention.

show abstract

“…1 The energy of such surface-adsorbate bonds relative to their initial unbound states (i.e., binding energy) is therefore an effective descriptor for catalytic activity, with a catalytic rate optimum existing for a reaction per the Sabatier principle. [2][3][4][5][6] Therefore, it is not surprising that a catalyst's inherent ability to transfer electrons to or from the reactants (via Lewis acidity and the d-band center for solid acid [7][8][9][10][11] and metal catalysts, [12][13][14] respectively) strongly correlates with catalytic reaction rates.…”

mentioning

confidence: 99%

Isopotential Titration for Quantifying Metal-Adsorbate Charge Transfer

Hopkins,

Wang,

et al. 2024

Preprint

View full text Add to dashboard Cite

The extent of charge transfer between adsorbed reactants and a catalyst surface plays a key role in determining binding energy and catalytic activity. Here, we describe the technique of ‘isopotential titration’ (IPT) to quantify the magnitude and direction of charge transfer between adsorbates and catalytic surfaces. The method used a ‘catalytic condenser’ device (Pt/C/70 nm HfO2/p++-Si) to evaluate the adsorption of hydrogen on a platinum-on-carbon conductive surface on a HfO2 (70 nm) film on a silicon wafer, with a potentiostat applying fixed (zero) voltage between the conductive Pt/C and silicon wafer layers. Dissociative adsorption of hydrogen on Pt resulted in electron flow through the external circuit from the Pt electrode toward the Si substrate, indicating that adsorbed hydrogen atoms donated electron density to the Pt surface, which then equilibrated with electrons flowing through the potentiostat to the silicon substrate. Desorption of hydrogen from the Pt surface exhibited equal and opposite current flow. The magnitude of the measured charge transfer upon hydrogen adsorption increased with increasing temperature from 100 to 200 °C, consistent with a larger change in H surface coverage at higher temperatures for cycling gaseous H2 partial pressures between 0.5% and 99.999%. Charge transferred from H atoms to the Pt was estimated as 0.17% of an electron donated per adsorbed H atom. The extent of charge transfer was comparable with a computed Bader charge analysis, which calculated an average of 0.4% of an electron transferred from adsorbing H to Pt at high surface coverage. With hydrogen adsorption being an example, isopotential titrations provide a new tool to quantify charge transfer events in heterogeneous catalytic systems.

show abstract

Lewis acidity and substituent effects influence aldehyde enolization and C–C coupling in beta zeolites

Cited by 8 publications

References 95 publications

Heteroatom Lewis acid zeolites: synthesis, characterization and application in the conversion of biomass-derived oxygenates

Heteroatom Lewis acid zeolites: synthesis, characterization and application in the conversion of biomass-derived oxygenates

From Lewis Acid to Lewis Base by La³⁺-to-Y³⁺ Substitution in α-YB₅O₉: Local Structure Modification Induced Lewis Basicity

Isopotential Titration for Quantifying Metal-Adsorbate Charge Transfer

Contact Info

Product

Resources

About

Lewis acidity and substituent effects influence aldehyde enolization and C–C coupling in beta zeolites

Cited by 8 publications

References 95 publications

Heteroatom Lewis acid zeolites: synthesis, characterization and application in the conversion of biomass-derived oxygenates

Heteroatom Lewis acid zeolites: synthesis, characterization and application in the conversion of biomass-derived oxygenates

From Lewis Acid to Lewis Base by La3+-to-Y3+ Substitution in α-YB5O9: Local Structure Modification Induced Lewis Basicity

Isopotential Titration for Quantifying Metal-Adsorbate Charge Transfer

Contact Info

Product

Resources

About

From Lewis Acid to Lewis Base by La³⁺-to-Y³⁺ Substitution in α-YB₅O₉: Local Structure Modification Induced Lewis Basicity