Pd-based catalytic hydrogenation has emerged as a promising and sustainable technology for contaminant removal. Supports are indispensible for Pd-based nanoparticles because they prevent nanoparticle aggregation and enhance catalyst recovery after use. Carbon nanofibers (CNFs) have shown its great potential as a catalyst support because of its large surface area, high mechanical strength, unique chemical reactivity, and economic feasibility. Pd-based nanoparticles were conventionally grown on surface-functionalized CNFs for improved dispersion; however, treatment of CNF surface (e.g., with strong acids at elevated temperature) is time consuming, energy intensive, difficult for handling, and non-sustainable due to waste generation. Our study aims to fabricate Pd loaded CNFs via a one-pot electrospinning and annealing with enhanced dispersion and surface exposure of Pd nanoparticles. Palladium acetylacetonate and polyacrylonitrile (PAN) were used as precursors for Pd nanoparticles and CNFs, respectively. Simply blending the Pd salt and PAN for electrospinning resulted in the majority of Pd nanoparticles embedded in CNFs after annealing and hence a little to no catalytic reactivity. Therefore, we created porous CNFs via sublimation of terephthalic acid for potential improvement of Pd exposure. We synthesized surface-loaded Pd on CNFs via electrospinning of a mixture of polyvinylpyrrolidone (PVP), PAN, and the Pd salt because of spontaneous concentric nanofiber formation with a PVP-Pd salt shell and a PAN core. Annealing burned off PVP completely and converted the as-spun concentric nanofiber into a surface loaded Pd on CNFs structure. Pd-CNF catalysts were characterized with scanning electron microscopy and transmission electron microscopy for fiber morphology, diameter, and Pd nanoparticle size. The catalysts will also be characterized by CO chemisorption and liquid N<sub>2</sub> adsorption to determine the surface area, porosity, and Pd nanoparticle exposure. Results have shown that Pd nanoparticles with a size of ca. 50 nm were successfully loaded on the exterior surface of CNFs, and that this catalyst was reactive for nitrite reduction. We will further optimize electrospinning parameters and annealing procedures to improve Pd dispersion and exposure, and explore application of Pd-CNF catalysts for decontamination. This one-pot electrospinning fabrication holds promise for catalyst fabrication with enhanced performance but reduced cost and post-treatment.

One-pot electrospinningfFabrication of Pd-carbon nanofiber catalysts for contaminant hydrogenation

249th National Meeting (2015)

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