Despite the growing adoption of solar power and other renewables, fossil fuels still rule our energy world. So, taking steps to make them cleaner is increasingly vital. The ability to convert coal and other carbon-containing compounds into liquid fuels requires a feedstock called syngas, a mixture of carbon monoxide (CO) and hydrogen (H2), which is highly polluting and created by cooking the feedstock under high temperatures and pressures.
Then, catalysts cause this syngas to react to form hydrocarbons that can be further altered to make fuels and other valuable chemicals. The chemistry is highly polluting, however. In one typical industrial setup, one-third of all the carbon contained in syngas ends up as CO2 vented into the atmosphere.
The standard synthetic fuels process uses iron-based catalysts to clip carbon atoms from CO molecules and link them to H2 molecules. Additional carbons and hydrogens can then link up to form a range of short hydrocarbon chains. But the catalyst can also cause leftover oxygen atoms that were separated from the CO molecules to react with hydrogen and form water which then reacts with CO to form useful H2 but also polluting CO2.
Chemists report in Science the discovery of an additive that sharply cuts carbon emissions from an industrial process that can convert coal, natural gas, or agricultural biomass to liquid fuels such as diesel or gasoline.
In the new work, researchers in China added trace amounts of compounds called halomethanes to their syngas mixture that block water molecules from binding and breaking apart, the first step in the pernicious CO2-generating side reaction.
