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A New Method to Dramatically Lower Sulfur Emissions from Diesel

lowering sulfur in diesel
Image Source: Bill McChesney, CC BY 2.0

A team of researchers in the US has developed a new method to lower the sulfur content of fossil fuels, specifically diesel fuel.

Fuels that are rich in sulfur produce sulfur dioxide that, when combusted, will react with water to form acid rain that harms the environment. Now, researchers Robert Grubbs from the California Institute of Technology, Kendall Houk from the University of California, and John Shabaker from British Petroleum (BP) have developed a simple, low-cost reaction that will be able to reduce sulfur content of diesel from 10,000 parts per million (ppm) down to just 2 ppm. Now, this is way below all the current emissions standards, which means that the method can greatly help with cutting world pollution.

Fundamentally, the process involves the breakdown of dibenzothiophenes, which are strong sulfur compounds that are normally difficult to remove. To be effective, it uses potassium tert-butoxide (strong base) and triethylsilane (reducing agent), which are easily available chemicals. The reaction is achieved at the comparatively low temperature of 165 degrees Celsius.

While there are methods that can reduce sulfur content in fuels to 10 ppm, which is the current EU standard, they require a metal catalyst, high-pressure hydrogen, and temperatures of 400 degrees Celsius, making things complicated. Less stringent standards are the reason why exported diesel often comes with higher sulfur content.

In their latest work, the team is working on ways to recycle silane that transforms into disilathiane after the process. Also, it is optimizing the new method for application in industrial refineries.