November 24, 2009 | 3 Comments
A lot of natural gas is lost, burned off or simply too remote to get to market. Several efforts have made press releases, but most are non-scalable or not cost effective. Yet, the lure of so much fuel and energy in remote natural gas is a strong enticement.
A catalyst manufactured by the American chemist Roy Periana over ten years ago from platinum and simple nitrogenous bipyrimidine effectively creates methanol, but only supports the reaction in a soluble form. That means that the catalyst — which chemists refer to as a homogenous catalyst — subsequently needs to be separated off in a laborious, expensive and somewhat wasteful process.
Scientists at the Max Planck Institute for Coal Research and at the Max Planck Institute of Colloids and Interfaces might make it worthwhile to harvest or tap into previously inaccessible natural gas resources. They have developed a catalyst based on Periana’s work that converts methane to methanol in a simple and efficient process.
The natural gas burned off throughout the world alone could more than satisfy Germany’s requirement for natural gas. It is not cost-effective to lay pipelines to remote or small natural gas fields; nor is it worthwhile to access the methane in coal seams or in gas sands, or which is burned off as a by-product of oil production. Then there is the methane in gas hydrates to consider as well. There is a lot of natural gas out there to harvest. It’s just too expensive to liquefy the gas and transport it by trucks, trains or in tankers. Chemistry research has so far been unable to offer an economic solution.
Ferdi Schüth, Director at the Max Planck Institute for Coal Research in Mülheim an der Ruhr and his colleagues have been working with Markus Antonietti and his team at the Max Planck Institute of Colloids and Interfaces in Potsdam to develop a catalyst that might change all this.
Schüth says, “When I saw the structure of covalent, triazine-based network (CTF), I noticed the elements which correspond to its bipyrimidine ligands. That’s when I had the idea of manufacturing the solid catalyst.”
The chemists in Potsdam synthesize the CFT. “This solid is so porous that the surface of a gram is approximately equivalent in size to a fifth of a football (soccer) field,” says Markus Antonietti. The researchers in Mülheim have built a voluminous lattice, inserted platinum atoms so the catalyst oxidizes the methane efficiently to methanol when immersed in sulfuric acid. Forcing in the methane at 215º C yields more than 75% of the methane into methanol.
Schüth explains, “It’s much easier with our heterogeneous catalyst,” they filter out the powdery platinum and CTF catalyst, and then separate the liquid acid and methanol in a simple distillation process.
To get closer to a large-scale technical application, the team is now attempting to enable the process to work with reactants in gaseous rather than soluble form. “We are also looking for similar, even more effective catalysts,” says Schüth. “We have already found more efficient homogenous catalysts with ligands other than bipyrmidine.” They are now using these as a model for simple, easy to manage catalysts like the CTF and platinum powder.
Methane is abundant in low concentrations, and the rich deposits, like gas formations and methane hydrates are widespread and in often remote or deep or inaccessible locations in sizes that preclude the investments needed for pipelining or liquefying, both capital-intensive operations for reaching markets. An example exists; in North America natural gas pipelines are widespread with markets also widespread already well connected. Eurasia though, has little gas near the markets, at great distances to the fields in Russia or the Middle East with large-scale development still underway or planned and even hoped for. It’s a very different situation. Europe will likely chose even more expensive imported liquefied natural gas to meet its demand.
Many believe that natural gas is far more abundant than reality makes clear. By no means has the industry invested as much in secondary recovery as in the oil field operations. In North America where the leading technology innovations are found, the effort to find and hook up new gas finds simply makes secondary recovery a sure way to lose money.
Even methane hydrates, a rich source of methane fuel is abundant, widespread and technologically challenging to recover. Perhaps the team’s new catalyst and process have a use there as well. Something much less expensive and ecologically kind is needed to harvest methane hydrates.
The Max Plank team is well on to something, just how it plays out has more opportunity than first impressions suggest. Let’s hope they get the gaseous catalyst and process worked out for scale up. Methane is a valuable thing to waste, especially on the European continent.
The team’s paper, Solid Catalysts for the Selective Low-Temperature Oxidation of Methane to Methanol appeared in the Volume 48, Issue 37, September 1, 2009 of Angewandte Chemie International Edition / DOI: 10.1002/anie.200902009.