“Converting glycerol into PG is simple chemistry,” Zacher says. “You snip off only a single OH group. But you have to do it selectively to make the process efficient and economical. The trick is finding the right catalyst — a finely tuned pair of chemical scissors to cut only the right bonds. The result is propylene glycol, water and a few byproducts.”
The right catalyst is essential because other catalysts and processes can make PG, but not cheaply enough to make commercial production feasible. The conversion process also produces a few byproducts, such as ethylene glycol, so the next step is to filter out those compounds to create pure PG.
“The PNNL team came up with a novel set of catalysts that enormously improved the capabilities to do this,” Bloom says. “That was the key. From there, we used their findings to scale up a technology for commercial production.”