Methane Reactions

By using gold dimer cations as catalysts, Georgia Institute of Technology and the University of Ulm scientists have converted methane into ethene at room temperature, and into methanal at temperatures below 250K (-9^o F). In both the room temperature reaction-producing ethene, and the methanal generation colder reaction, the gold dimer catalyst is freed at the end of the reaction, thus enabling the catalytic cycle to repeat again and again.

The temperature-tuned catalyzed methane partial combustion process involves activating the methane carbon-to-hydrogen bond to react with molecular oxygen.
In the first step of the reaction process, methane and oxygen molecules coadsorb on the gold dimer cation at low temperature.
Subsequently, water is released and the remaining oxygen atom binds with the methane molecule to form methanal.
If done at higher temperatures, the oxygen molecule comes off the gold catalyst, and the adsorbed methane molecules combine to form ethene through the elimination of hydrogen molecules.

Reference
Sandra M. Lang, Thorsten M. Bernhardt, Robert N. Barnett, Uzi Landman. Temperature-Tunable Selective Methane Catalysis on Au2 : From Cryogenic Partial Oxidation Yielding Formaldehyde to Cold Ethylene Production. The Journal of Physical Chemistry C, 2011; 115 (14): 6788 DOI: 10.1021/jp200160r

Further Reading
Balancing Chemical Equations
Nomenclature
Combustion of Hydrocarbons
Oxidation and Reduction
Oxidation States (Numbers)

Study Questions

1. Write the molecular formula for each of the following:
   
   • methane
   • methanal
   • ethene
2. Draw the structural formula for each of the following:
   
   • methane
   • methanal
   • ethene
3. On the structural formula above, identify the functional groups present in methanal and ethene.
   
4. The following molecules are known by other names. Give atleast one other name used for each of the following:
   
   • methane
   • methanal
   • ethene
5. Write a balanced chemical equation for each of the following reactions involving the gold dimer cation catalyst:
   
   • methane and oxygen react to form methanal and water
     
   • methane and oxygen react to form ethene and water
6. Classify each reaction above as an oxidation or a reduction reaction. Justify your answer.
   
7. Write balanced chemical equations to represent the combustion of methane at high temperature, without the aid of a catalyst, under each of the following conditions:
   
   • excess oxygen
   • excess methane
8. Compare the chemical equations in question 7 to those in question 5. In what ways are the reactions similar? In what ways are the reactions different?