A team of molecular biologists and materials scientists said Monday they had genetically engineered a virus to convert methane to ethylene more efficiently and at a significantly lower temperature than previously possible. Methane gas is still produced by steam cracking, a high-temperature, energy-intensive and expensive industrial process first developed in the 19th century. In this process, hydrocarbons found in crude oil are broken down into a range of simpler chemical compounds. The search for more efficient, less expensive approaches to the production of ethylene has gone on for more than three decades, and although some progress has been made no new techniques have yet proved commercially viable.
Now a small group of researchers at Siluria Technologies, a Silicon Valley startup is reporting progress in commercializing a nanoscience-based approach to ethylene production. Their technique for producing ethylene depends on the ability of a genetically engineered virus to coat itself with a metal that serves as a catalyst for an ethylene producing chemical reaction. The key is that the virus can create a “tangle of catalyst coated nanowires — the researchers call it a hairball — that provide so much surface area for chemical reactions to occur that the energy needed to produce the reactions is much reduced. The basic process, or chemical reaction, known as oxidative coupling of methane, was an area of intense research for the petrochemical industry beginning in the late 1980s. Researchers had some success but never achieved enough of an improvement in energy efficiency to justify displacing the traditional steam-cracking process. With its hairballs of virus-created nanowires coated with unspecified metals, Siluria has been able to create ethylene-producing reactions at temperatures 200 to 300 degrees lower than previously achieved, said Erik Scher, a chemist who is one of the company’s researchers. The company won’t say specifically what the coating is, but say that magnesium oxide is an example of the kind of metals involved. The work is based on a technique for genetically engineering viruses pioneered by Angela Belcher, who leads the Biomolecular Materials Group at MIT. The technique involves manipulating the genes of a virus, in this case one that usually attacks bacteria, so that it will collect and coat itself with inorganic materials, like metals and even carbon nanotubes. The viruses can be used to create a dense tangle of metal nanowires, and the potential applications for these engineered materials are remarkably diverse. Dr. Belcher’s lab is busy with research on more efficient batteries and solar cells, biofuels, hydrogen separation and other fuel cell technologies, CO2 sequestration, cancer diagnostic and therapeutic approaches, as well as an effort to create a catalyst that can convert ethanol to hydrogen at room temperature.
In contrast, the Siluria researchers said their advance in developing catalysts is the most significant step yet toward commercialization of the bacteriophage technique. “We are learning from nature, but going to new places in the periodic table and working with the same tools and techniques to use materials that nature has not worked with,” said Alex Tkachenko, a molecular biologist who is a co-founder of Siluria. The researchers acknowledged that they do not yet have a complete scientific understanding of the surface behavior of their new catalyst.