A relatively low-cost means of converting carbon dioxide into methanol has been developed by researchers from Stanford University, SLAC National Accelerator Laboratory, and the Technical University of Denmark.
Methanol is used for a number of different purposes, primarily though, as a fuel, in the production of many important adhesives and solvents, and in the production of plastics. It’s been suggested by researchers in some fields that methanol could be used as a replacement for gasoline (at least partially) — despite its corrosivity — with only minimal adjustments to vehicle design.
The new low-cost conversion method is all down to the discovery of a new nickel-gallium catalyst — one that converts hydrogen and carbon dioxide into methanol with fewer side-products than the conventional catalysts.
“Methanol is processed in huge factories at very high pressures using hydrogen, carbon dioxide and carbon monoxide from natural gas,” stated study lead author Felix Studt, a staff scientist at SLAC. “We are looking for materials than can make methanol from clean sources under low-pressure conditions, while generating low amounts of carbon monoxide.”
Ultimately, according to Studt, the goal is a process that can be scaled up to the industrial level while remaining “nonpolluting and carbon neutral”.
“Imagine if you could synthesize methanol using hydrogen from renewable sources, such as water split by sunlight, and carbon dioxide captured from power plants and other industrial smokestacks,” explained co-author Jens Nørskov, a professor of chemical engineering at Stanford. “Eventually we would also like to make higher alcohols, such as ethanol and propanol, which, unlike methanol, can be directly added to gasoline today.”
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Worldwide, about 65 million metric tons of methanol are produced each year for use in the manufacture of paints, polymers, glues and other products. In a typical methanol plant, natural gas and water are converted to synthesis gas (“syngas”), which consists of carbon monoxide, carbon dioxide and hydrogen. The syngas is then converted into methanol in a high-pressure process using a catalyst made of copper, zinc and aluminum.
Once Studt and his colleagues understood methanol synthesis at the molecular level, they began the hunt for a new catalyst capable of synthesizing methanol at low pressures using only hydrogen and carbon dioxide. Instead of testing a variety of compounds in the lab, Studt searched for promising catalysts in a massive computerized database that he and co-author Frank Abild-Pedersen developed at SLAC. Comparing the copper-zinc-aluminum catalyst with thousands of other materials in the database, the most promising candidate turned out to be a little-known compound called nickel-gallium.
“Once we got the name of the compound out of the computer, someone still had to test it,” Nørskov stared. “We don’t do lab experiments here, so we have to have a good experimental partner.”
That’s where the research group at the Technical University of Denmark came in — synthesizing and testing the nickel-gallium catalyst. The tests confirmed what had been predicted — “at high temperatures, nickel-gallium produced more methanol than the conventional copper-zinc-aluminum catalyst, and considerably less of the carbon monoxide byproduct.”
“You want to make methanol, not carbon monoxide,” Chorkendorff said. “You also want a catalyst that’s stable and doesn’t decompose. The lab tests showed that nickel-gallium is, in fact, a very stable solid.”
The researchers are now working to fine-tune their new catalyst.
The new findings were just published in the journal Nature Chemistry.
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