While some researchers are proposing the idea of using a platinum catalyst to keep methane out of the atmosphere, a group of British, Chinese and American scientists demonstrated, for the first time, the direct conversion of methane into methanol and acetic acid using a gold catalyst.
In a paper published in the journal Nature Catalysis, the team explains that methane accounts for 70-90% of natural gas. The super-warming greenhouse gas, which is capable of trapping over 80 times more heat than carbon dioxide in its first two decades in the atmosphere, is also emitted in big quantities by the coal mining industry.
To make use of it by turning it into more useful products, the scientists looked at what other researchers have done and concluded that although their achievements are notable, their methods include multiple steps that are highly energy consuming and very costly. Thus, they decided to achieve the creation of methanol and acetic acid by reacting methane with oxygen in the presence of a catalyst made from gold and the zeolite ZSM-5.
By examining the catalyst using high-powered electron microscopy, it was revealed that the active catalyst did not contain gold atoms or clusters, but rather gold nanoparticles – extremely small particles between 3 to 15 nanometres in size – that can exhibit significantly different physical and chemical properties to their larger material counterparts.
The production of methanol using this catalyst was expected; however, the novelty of the new method came in the production of acetic acid.
Acetic acid is a common industrial chemical with large quantities used to make products such as ink for textile printing, dyes, photographic chemicals, pesticides, pharmaceuticals, rubber and plastics.
Methanol, meanwhile, is commonly used as a precursor to many other commodity chemicals, as well as a biofuel.
“The oxidation of methane, the main component of natural gas, to selectively form oxygenated chemical intermediates using molecular oxygen has been a long-standing grand challenge in catalysis,” Graham Hutchings, one of the paper’s co-authors, said in a media statement.
“We have successfully demonstrated this for the very first time in this study, providing an important first step towards the creation of important fuels and chemicals in a simple and cost-effective way.”