Light-powered catalyst generates hydrogen energy from pungent gas in a one-step process

Rice University engineers and scientists have created a brilliant way for refineries and petrochemicals to turn a smelly by-product into cash.

Hydrogen sulfide The gas has an unmistakable characteristic odor of rotten eggs. It is commonly emitted from sewers, stockpiles and landfills, but it is especially problematic for refineries, petrochemical plants and other industries, where thousands of tons of toxic gases are generated. damage each year as a by-product of processes that remove sulfur from petroleum, nature Aircoal and other products.

In a study published in Energy letter ACSRice engineer, physicist and chemist Naomi Halas and colleagues describe a method that uses gold nanoparticles to convert hydrogen sulfide high demand hydrogen gas and sulfur in a single step. Better yet, the one-step process gets all its energy from the light. Co-authors of the study include Rice’s Peter Nordlander, Princeton University’s Emily Carter, and Syzygy Plasmonics’ Hossein Robatjazi.

“Emissions of hydrogen sulfide can lead to money,” said Halas, a pioneer in nano-optical engineering who has spent years developing commercially viable light-activated nanocatalysts. Huge fine for the industry. “The phrase ‘game changer’ is overused, but in this case it applies. Performing plasmonic photocatalysis will be much less expensive than traditional processing and it has the added potential of turning a costly burden into an increasingly valuable commodity.”

Each molecule of hydrogen sulfide gas (H₂S) contains a pair of hydrogen atoms and a sulfur atom. Each clean-burning hydrogen gas molecule (H₂) – the staple commodity of the hydrogen economy – contains a pair of hydrogen atoms. In the new study, Halas’ team dotted the surface of silicon dioxide powder particles with tiny gold islands.

Each island is a gold nanoparticle about 10 billionths of a meter across that will interact strongly with a specific wavelength of visible light. These plasmonic reactions produce “hot carriers,” short-lived, high-energy electrons that can drive catalysis.

In the study, Halas and co-authors used a laboratory setup and showed that an array of LEDs can efficiently generate hot carrier photocatalysts and convert H.₂S directly into the HOUSE₂ gas and sulfur. That is in stark contrast to the established catalytic technology that refineries use to break down hydrogen sulfide.

Called the Claus process, it produces sulfur but no hydrogen, which it converts to water instead. The Claus process also requires multiple steps, including some that require the combustion chamber to be heated to about 1,500 degrees Fahrenheit.

The plasmonic hydrogen sulfide treatment technology has been licensed by Syzygy Plasmonics, a Houston-based startup with more than 60 employees whose co-founders include Halas and Nordlander.

Halas said the process could end up costing sufficiently low to perform and efficient enough to be economical to clean non-industrial hydrogen sulfide from sources such as emissions and animal waste.

“Since it only requires visible light and no external heating, scaling it up using renewable solar energy or highly efficient solid-state LEDs will be relatively simple,” she said. simple.