The use of natural gas for the chemical industry is a valued method that can lead to the production of not only fuels but polymers and pharmaceuticals. The reaction they were focused on is called the oxybromination of methane, which can currently be carried out but with a less effective catalyst.
The reaction requires the scientists to replace a hydrogen atom in methane with a bromine atom while using a specific catalyst. Vanadium phosphate turned out to be the best catalyst. The scientists were interested in improving the reaction’s selectivity and went through several possibilities before selecting vanadium phosphate. The types of catalysts used in the past were called reaction accelerators which generated large amounts of unwanted materials
Vanadium phosphate offered many advantages. It is a mild oxidizing catalyst in that it will not oxidize unwanted products, but is strong enough to let hydrogen bromide reaction with oxygen at the surface of the catalyst. The catalyst provides selectivity for methyl bromide up to 95%. Compared to other options, vanadium phosphate offers much more stability.
The new method also effectively conserves bromine in the process. Pérez-Ramírez explains, “The beauty of our reaction is that it enables the bromine from hydrogen bromide to be embedded back into methyl bromide, using oxygen. In this way, the bromine cycle is closed, and no bromine is lost.”
With a new catalyst, the reaction outpaces current energy-intensive measures that require high pressure and high temperature. In just one step, methane can now be converted at a favorable pressure and temperature. The ability to generate larger quantities of natural gas with an easier method paves the way for a more efficient chemical production process.