The Dual Subsurface Hydrogen (2H') Mechanism for Ethylene Hydrogenation on Pd
Nicholas Golio1, Andrew J Gellman1,2
1Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213, United States.
Summary
A new Dual Subsurface Hydrogen (2H') mechanism accurately models ethylene hydrogenation on palladium (Pd) surfaces. This model, incorporating subsurface hydrogen, aligns with experimental data and improves understanding of catalytic reactions.
Area of Science:
- Surface Science
- Chemical Kinetics
- Catalysis
Background:
- The Horiuti-Polanyi framework is a key model for surface reactions.
- Existing models like Langmuir-Hinshelwood have limitations, particularly for H2-D2 exchange.
- Subsurface hydrogen (H ) plays a role in activating surface reactions on palladium.
Purpose of the Study:
- To develop a microkinetic model for ethylene hydrogenation on Pd that includes subsurface hydrogen.
- To extend the Horiuti-Polanyi framework with a Dual Subsurface Hydrogen (2H ) mechanism.
- To validate the 2H mechanism against experimental data for ethylene hydrogenation on Pd.
Main Methods:
- Developed a microkinetic model based on the Horiuti-Polanyi framework.
- Incorporated the Dual Subsurface Hydrogen (2H ) mechanism to account for subsurface hydrogen.
- Compared model predictions with experimental results for ethylene hydrogenation on AgxPd1-x Composition Spread Alloy Films (CSAF).
Main Results:
- The 2H mechanism accurately predicted the reaction order in H2 for ethylene hydrogenation (0.69 ± 0.18).
- Estimated the effective hydrogenation rate constant (k_eff) to be between 10^10 and 10^14 mol/m^2/sec.
- Determined the ethylene adsorption energy to be approximately 10 kJ/mol.
Conclusions:
- The Dual Subsurface Hydrogen (2H ) mechanism provides an accurate representation of ethylene hydrogenation on Pd.
- Considering subsurface hydrogen is crucial for precise modeling of surface reactions on palladium-based catalysts.
- The 2H mechanism offers a more robust framework for understanding complex catalytic processes.
![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)
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