Materials screening 'improves' biofuel processing

Using a supercomputer at the Argonne National Laboratory in Chicago, US, the University of Minnesota-led team said its discovery could lead to “major efficiencies and cost savings” within the renewables and petroleum-based industries.

To produce upgraded fuels, refineries use minerals called zeolites that act as molecular sieves to sort, filter, and trap chemical compounds, as well as catalyse chemical reactions, the researchers said.

“We’re looking for materials that have interesting properties and that’s what we’ve achieved here

Rice University chairman Micheal Deem

Currently, there are more than 200 known zeolites and thousands of predicted zeolite variations.

The key to improving biofuel and petrochemical processes is to find the zeolites that are most efficient, the researchers said.

To analyse both the known and predicted zeolite structures, the researchers developed a ’virtual world’ which rapidly identified zeolite performance within specific applications.

“Using [the Argonne] supercomputer, we are able to use our computer simulations to compress decades of research in the lab into a total of about a day’s worth of computing,” said lead researcher Ilja Siepmann, a professor of chemistry at the University of Minnesota.

Utilising roughly 800,000 processors, running the equivalent of 10 million hours of computations, the study identified zeolites which could attack two complex problems.

The first problem researchers tackled was the current multi-step ethanol purification process used in biofuel production. In this process, one of the final steps involves the separation of ethanol from water.

Researchers found a few all-silica zeolites with superior performance that contain pores and channels with the ability to accommodate ethanol molecules but to shun hydrogen bonding with water molecules.

One of these zeolites was found to be so effective that it could change the ethanol/water separation process from a multi-step distillation process to a single-step adsorptive process, the researchers said.

Meanwhile, the researchers also targeted the upgrading of petroleum compounds into higher-value lubricant and diesel products.

To do this, the researchers identified zeolite frameworks that could improve the dewaxing process of transforming linear long-chain into slightly branched hydrocarbon molecules, called alkanes, which affect the pour point and viscosity of lubricants and other petroleum products.

Researchers said that “defining appropriate sorbents and catalysts for all of the complex mixtures involved in creating these products is of paramount importance”, but has been one of the most difficult problems to overcome.

“We’re looking for materials that have interesting properties and that’s what we’ve achieved here,” said study co-author Michael Deem, chairman of Rice University’s Department of Bioengineering.