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Computational Quantum Chemical Analysis of Platinum Catalysts in Methane to

Methanol Conversion ProcessAmit Kothekar

Abstract

The earth today is home to the consumption of many resources and fuels. For example, it contains the depletion of non-renewable resources such as oil, gasoline and other fossil fuels. Additionally, daily life results in the habit of using renewable resources such as electricity although it is not applied in a wide perspective. Lately, investment has gone into expediting the usage of renewable resources in terms of replacing non-renewable resources. This is all in an effort to discontinue the reliance on destructive fossil fuels. As a result, not only is the world turning to the search for “new” energy sources, but also to the optimization and refinement of current sources. This is why catalysis of the methane to methanol reaction was a successful source of energy to choose. It was hypothesized that a platinum oxide complex would successfully reduce the amount of energy required needed to produce an exothermic reaction. The validity of this was carried out through computational means. Three overall methods, Hartree Fock, Moller Plesset and Density Functional Theory were used. Each of the methods correctly approximated the wavefunction and energy of the molecule. Quantum mechanically, it was necessary due to complications and relations at the quantum level that needed to be counted for. A consistent low stable energy of -134 Hartrees for a Platinum Oxide Compound showed that the most stable multiplicity was triplet. Likewise, consistent energies of -7 Hartree and -23 Hartree were calculated for methane and methanol. The addition of a halide (Chlorine) allowed the introduction of more energy while increasing molecular stability, a characteristic essential for catalysis. Although DFT computations resulted in a non-SCF convergence error, Hartree-Fock and Moller Plesset allowed optimization graphs and geometries to be manifested. Platinum Oxide with a halide (PtOCl) was substantially higher at -149 Hartrees of potential energy and DFT computations allowed the creation of a reaction coordinate that displayed a lower activation energy than the non-catalyzed reaction. Calculation of the individual potential energies of the products and input into a balanced reaction showed a large enthalpy change between the products and reactions that was approximately -13 kcal/mol. Essentially, the exothermic reaction was potentially stable enough to result in a 6500 Kelvin differential.

Background Points

• Modern day energy sources encompass a wide range of resources encompassed into two categories, renewable and non-renewable resources

• Problems with modern day energy resources is that they are harmful to the environment in that some such as Nuclear Energy release nuclear waste while others such as fossil fuels release greenhouse gases

• Much investment has gone into the search for the most optimal energy resource with the Obama Administration investing $2 billion in new energy research

• The world is looking to optimize current methods as “future” resources are not as efficient as needed

• Methanol is an already used fuel source. The creation of this compound from methane has been regarded as an already useful fuel source.

• The conversion process is not as energy efficient as possible since it takes a lot of chemical work to convert methane

• Catalysts are recognized as the most possible way to achieve this efficiency

• Transition metals are the best catalysts due to the fact that they have open d-orbitals for each individual atom. This allows them to become more flexible in their reactivity and properties.

• Density Functional Theory has made significant progress with its capabilities and is integral to the experiment

Peak Oil

Alternative Energy

Wind Energy Inefficient for urban usage

Solar Power Inefficient in terms of energy consumption

Hydroelectric Can be unstable and cause unknown environmental

issues

The Current Process

Methane to Methanol is a conversion process converting between two biological compounds Can be done naturally by some organisms Low density, causes transportation issues Industrial process releases large amounts of

greenhouse gases

Catalytic Promise

Transition Metals

Significance

Alternative energy source

Reduction of cost to energy ratio

Reduced greenhouse gas emissions

Safer fuels

Optimization of battery performance

Industrial application

Materials + Methods

Computational Quantum Chemical methodologies

- Hartree Fock Method

- Moller Plesset Method

- Density Functional Theory

Linux/Unix programming for VNC access

Python and MATLAB for simple mathematical tests and modeling

Cross-checking of CQC methods for increased accuracy

Sample GAMESS ID

Mathematical Basis

)()(4

)( 22

2

rrVh

rE

• Time Independent Schrödinger Equation• Basis for all methodology• Simplistic analysis and evaluation in a time

independent system

Hartree- Fock Method

Method developed to approximate the wavefunction of a time independent multi-body system

Slater Determinant of spin orbital functions of position and spin Used to calculate the wavefunction for a N-electron

system

Important Quote

“If you think you understand quantum mechanics, you don’t” – Richard Feynman

Data and Results

Methane

Platinum Chloroxide

Platinum and Palladium Atoms

Wavefunction ComparisonPalladium Atom Wavefunction

Platinum Atom Wavefunction

The Catalysis

Input (in kcal/mol): -93611.1 + -4895.6 -14733.3 + -83786.9∆E = -13.5 kcal/mol or 54.4 kJ/mol

Discussion

Analysis of Results

• A stabilization of energy was found to be -134.4 Hartrees

• Negative energy values signifies exothermic properties

• Platinum Oxide Compound energies ended up null for Density Functional Theory Calculations but not HF and MP2

• Molecular geometric stabilization occurred

• Intrinsic Reaction Coordinate calculations resulted in a predicted exothermic reaction

• Molecules had small optimization steps resulting in a flatter optimization graph

• Overall enthalpic change was -13 kcal/mol

Future Research

• Analysis of metals from non platinum group root with another oxide complex

Acknowledgements

Dr. Vladimir Shapovalov, PhD Mathematic,s PhD Physics The Bronx High School of Science

University of Sydney for open source software and MATLAB code