Tungsten Oxide Clusters
Figure 1. An atomic-level image of tungsten oxide nanoparticles (green circles) on zirconia support. The other circles show the less-active forms of tungsten oxide.
Source: Wu Zhou/Lehigh UniversityHe says now that the catalyst formula is "just right."
Recent studies show that after two catalytic cycles, overall activity remained practically the same, adds Wong, a professor of chemical and biomolecular engineering and of chemistry. "We expect the catalyst to have a longer life due to the absence of chloride species (used in industrial isomerization catalysts) that eventually leach out causing serious regeneration issues," he says.
Besides pentane isomerization, other chemical reactions that might benefit from the catalyst include acidic reactions such a paraffin, olefin and aromatic compound isomerization, dehydration of paraffins to olefins, esterification reactions, hydrolysis and metathesis.
"These are reactions of great importance for the petrochemical industry, especially in fuel enrichment technologies. We are starting to investigate metathesis in our lab, because we think that other forms of the surface tungsten can be good for this reaction," says Wong.
Wong and his team are also investigating optimization of the surface coverage of other catalytic nanomaterials that are used on supports. "We've started putting molybdenum oxide and vanadium oxide in place of tungsten oxide using a new synthesis technique we are developing," he says.
Producing the catalyst on a large scale should be straightforward, notes Wong. Lab samples were made using conventional dry impregnation — the most common method used commercially. Industrial firms already have expressed interest in cooperating on further development.
Using the catalyst in existing reactors doesn't require any major modifications, he adds.