Making Methanol

Methanol as an energy source can be used as a fuel in the same way as petrol (gasoline), or it can be used in fuel cells. About 90% of the worldwide production of methanol is derived from methane, the main component of natural gas. Current methods for producing this methanol involve converting methane into syngas, a mixture of carbon monoxide and hydrogen, and then converting this syngas into methanol. Eliminating the syngas stage would dramatically reduce the cost of producing methanol.
But methane is not very reactive, and combines readily with oxygen only at high temperatures. A catalyst helps, but commonly used catalysts themselves work only at 300^oC or higher. At these temperatures, most of the methanol produced is oxidized to carbon dioxide and water. Indeed, methanol yields from such reactions can be as low as 2%.

A lower temperature catalyst such as platinum dissolved in concentrated sulfuric acid at 200^oC, has achieved a methanol yield of more than 70% in the laboratory, but platinum is an expensive metal.

Methane can also be converted to methanol in the laboratory using a halogen such as bromine. Using a suitable catalyst at 250^oC methane reacts with bromine to form bromomethane (methylbromide) and hydrogen bromide. Bromomethane (methyl bromide) then reacts with water to form methanol. The bromine from the hydrogen bromide can be recovered by reaction with air, and reused.

Methanol can be made by combining carbon dioxide and hydrogen. Such a process requires considerable energy just to harvest the hydrogen from water, for example. The carbon dioxide could be captured from flue gases, and even directly from the atmosphere.

Further Reading
Nomenclature
Alcohols
Balancing Chemical Equations
Combustion of Hydrocarbons
Halogenation of Hydrocarbons
Fuel Cells and Batteries
Temperature Conversions
Ideal Gas law
Yield

Study Questions

1. Write the chemical formula for each of the following:
   
   • methanol
   • methane
   • carbon monoxide
   • hydrogen gas
   • oxygen gas
   • carbon dioxide
   • water
   • bromine liquid
   • bromomethane (methylbromide)
   • hydrogen bromide
2. Write balanced chemical equations for each of these reactions:
   
   • carbon monoxide + hydrogen gas → methanol
   • carbon dioxide + hydrogen gas → methanol
     
   • methane + oxygen gas → carbon dioxide gas + water
   • methane + oxygen gas → methanol
   • methane + bromine liquid → bromomethane + hydrogen bromide
   • bromomethane + water → methanol + hydrogen bromide
     
   • water → hydrogen gas + oxygen gas
3. Convert the following temperatures in ^oC to Kelvin
   • 200^oC
   • 250^oC
   • 300^oC
   
   
4. For the reaction between methane and oxygen to produce methanol, calculate the theoretical yield of methanol that could be produced from 100kg of methane.
5. Using the platinum-based sulfuric acid catalyst at 200^oC, yields of 70% have been achieved for the above reaction.
   • What mass of methanol is actually produced during this reaction if you start with 100kg of methane?
   • Convert this mass to moles.
   • Calculate the volume of methanol gas produced.
     
6. At 300^oC the yield of methanol produced from the reaction between methane and oxygen is 2%. Assume the reaction starts with 100L of methane gas
   • Calculate the moles of methane gas in the reaction mixture
   • Calculate the theoretical yield of methanol that could be produced
   • Calculate the actual yield of methanol
7. Why do you think it is important for Chemists to continue to search for inexpensive catalysts for the methane to methanol reaction?