Development and application of carbon nanofibers based nanostructured catalyst support layer for microreaction systems

摘要

Carbon materials have been attracting attention as potential catalysts support materials in heterogeneous catalysis due to their unparalleled flexibility in tailoring catalyst properties to specific needs. Preparation of carbon nanostructured materials such as carbon nanofibers (CNFs) and/or tubes (CNTs) and exploration of their prospect toward novel catalytic applications has been of great importance to the scientific community. One such field of application has seen recently a surge in research on investigating the use of nanostructure carbon materials as structured catalyst support for microreaction systems. Currently, there is tremendous interest in the use of microreactors especially for multiphase (fluid-solid) chemical reactions, because they feature significant enhancement in interfacial area in multiphase flows, enhanced heat (safety) and mass transfer (kinetic control) properties; all achieved due to very small dimensions of the internal structures (such as microchannels) of microreactors. However, integration of a solid catalytic phase in such reactors is a formidable task. Commonly used options are, (i) using a micro packed-bed of powdered catalyst particles or (ii) thin layer catalyst coatings on reactor walls. These options limit efficiency of catalyst use, in the former case microporosity limited mass transfer and pressure drop are issues, while thin catalyst coating offer limited catalytic sites and hence low catalytic activity. Incorporation of solid nanostructural elements in the microreactors, that can support catalytic phase, offer a way to overcome these problems because (i) microporosity and related diffusion limitations are minimized, (ii) the resulting high surface-to-volume ratios, provide enhanced interface crucial for accelerating multiphase reactions. In this work we show development and suitability CNFs, to overcome the problems stated above. The prepared materials (i.e. Ru/CNF in microreactor) were tested for catalytic reduction of bromate, which is one of the ozonation by-products in a drinking water treatment and a possible carcinogen.