(341e) Reactions Catalyzed By Metal Particles Supported on Functionalized Carbon Nanotubes in Biphasic Systems

Carbon nanotubes in biphasic systems have recently gained attention as Pickering emulsion stabilizers in the areas of underground oil recovery and heterogeneous catalyst supports due to their ability to undergo functionalization and tune the surface chemistry while maintaining the nanotube’s unique electronic and physical properties [1-4]. While a great deal of literature exists for nanoparticle stabilized Pickering emulsions, very little is known about the fundamental behavior of nanotubes as Pickering emulsion stabilizers. In this contribution, Pd nanoparticles are supported on multiwalled carbon nanotubes with varying degrees of defects and hydrophilic functional groups. A combination of detailed emulsion characterization is coupled with phase specific chemical reactions to quantify both the location of functionalized carbon nanotubes at an oil/water interface, as well as the role of diffusion across the interface for enhanced reaction control.

A combination of acoustic spectroscopy, optical microscopy, SEM and TEM images of thin cross sections of the Pickering emulsions is used to quantify the influence of various surface functional groups on the interfacial area stabilized by carbon nanotube emulsions, as well as their orientation at the oil/water interface. This information is coupled with chemical reactions of olefins and small oxygenates with exclusive solubility in either the oil or water phase to measure the number of catalytic particles in each phase, as well as the rate of diffusion across the oil/water interface. Finally, this information is used to prepare novel hybrid emulsions containing blends of carbon nanotubes with various functional groups to create a gradient in catalytic particles along the oil/water interface enabling the enhanced control of chemical reactions in biphasic systems. 

References:

[1] Crossley, S., Faria, J., Shen, M., & Resasco, D. E. (2010). Solid nanoparticles that catalyze biofuel upgrade reactions at the water/oil interface. Science, 327(5961), 68-72.

[2] Shen, M., & Resasco, D. E. (2009). Emulsions Stabilized by Carbon Nanotube− Silica Nanohybrids. Langmuir, 25(18), 10843-10851.

[3]Drexler, S., Faria, J., Ruiz, M. P., Harwell, J. H., & Resasco, D. E. (2012). Amphiphilic nanohybrid catalysts for reactions at the water/oil interface in subsurface reservoirs. Energy & Fuels, 26(4), 2231-2241.

[4]Shi, D., Faria Albanese, J. A., Pham, T. N., & Resasco, D. E. (2014). Enhanced Activity and Selectivity of Fischer-Tropsch Synthesis Catalysts in Water/Oil Emulsions. ACS Catalysis.