A research team at the University of Washington and the University of North Carolina at Chapel Hill has made important progress in converting methane gas to methanol. The process would make natural gas more useful as a liquid fuel and as a source for making other chemicals.
The team uses methane, the primary component of natural gas, a plentiful and an attractive fuel and raw material for chemicals because it is more efficient than oil, produces less pollution and could serve as a practical substitute for petroleum-based fuels until renewable fuels are widely useable and available. Note that making methane from biomass isn’t particularly difficult. The research could lead to a new step in a process of biomass to fuels.
Methane’s main disadvantages are its difficult and costly to transport because it remains a gas at temperatures and pressures typical on the Earth’s surface, requiring dedicated pipelines to get it to markets and highly pressurized and cooled tanks for storage.
The UW and UNC scientists have found a step for devising a way to convert methane to methanol or other liquids that can easily be transported, especially from the remote sites where natural gas is often found. The huge investments in natural gas production are becoming more of the liquefaction effort to make the gas transport ready.
Methane is so attractive and valued because of the molecule’s high-energy single carbon and four hydrogen atom bonds. Methane doesn’t react easily with other materials, so it is most often simply burned as fuel. Oxidizing breaks all four hydrogen-carbon bonds and produces carbon dioxide and water, said Karen Goldberg, a UW chemistry professor in the UW news release introduction.
Goldberg explains converting methane into useful chemicals, including readily transported liquids, currently requires high temperatures and a lot of energy. Catalysts that turn methane into other chemicals at lower temperatures have been discovered, but they have proven to be too slow, too inefficient or too expensive for industrial applications. Binding methane to a metal catalyst is the first step required to selectively break just one of the carbon-hydrogen bonds in the process of converting natural gas to methanol or another liquid.
The research paper describes the first observation of a metal complex (a compound consisting of a central metal atom connected to surrounding atoms or molecules) that binds the methane in solution. This compound thus serves as a model for other possible methane complexes. Within the complex, the methane’s carbon-hydrogen bonds remained intact as they bound to a rare metal called rhodium.
Goldberg says, “The idea is to turn methane into a liquid in which you preserve most of the carbon-hydrogen bonds so that you can still have all that energy. This gives us a clue as to what the first interaction between methane and metal must look like.”
Maurice Brookhart, a chemistry professor over at UNC said the carbon-hydrogen bonds are very strong and hard to break, but in methane complexes breaking the carbon-hydrogen bond becomes easier. Brookhart says, “The next step is to use knowledge gained from this discovery to formulate other complexes and conditions that will allow us to catalytically replace one hydrogen atom on methane with other atoms and produce liquid chemicals such as methanol.”
The team’s work should spur further advances in developing catalysts to transform methane into methanol or other liquids, Goldberg said. She noted that actually developing a process and being able to convert the gas into a liquid chemical at reasonable temperatures still is likely some distance in the future. But it’s still substantial progress.
The lead author of the paper is Wesley Bernskoetter, who is now at Brown University, did the work while at UNC. Goldberg, Brookhart and Cynthia Schauer, associate chemistry professor at UNC, are the co-authors.
The work comes out of a major National Science Foundation-funded collaboration, the UW-based Center for Enabling New Technologies Through Catalysis, directed by Goldberg, that involves 13 universities and research centers in the United States and Canada, including UNC. The Center’s goal is aimed at finding efficient, inexpensive and environmentally friendly ways to produce chemicals and fuels. Additional funding came from the National Institutes of Health.
When you think about methane, one reaches out much further than natural gas. The climate change crowd rails about cattle belches, farts and manure emissions, but all animals are sourcing methane to the atmosphere, some of which could be captured. That can include the vent over every restroom and bathroom, the sewers, water treatment plants and landfills. The total methane availability is stunning.
A low temperature catalyst available to install across the spectrum of sources would make a lot of fuel available. Products are already coming; Toshiba Corp has launched the company’s first direct methanol fuel cell (DMFC) product, the Dynario, as an external power source that delivers power to mobile digital consumer products.
With an injection of methanol solution from its dedicated cartridge, Dynario starts to generate electricity that is delivered to a digital consumer product (i.e. a mobile phone or a digital media player) via a USB cable. On a single refill of methanol, which can be made in an around 20 seconds, Dynario can generate enough power to charge two typical mobile phones.
This writer would love to escape the cell phone charger with a squirt of methanol. The technology is coming and the UW and UNC research team has made a significant discovery to get the fuel production process ready.