Silicon based microreactors for catalytic reduction in aqueous phase: Use of carbon nanofiber supported palladium catalyst

Carbon nanofiber layers containing palladium particles were synthesized inside the channels of a silicon based microreactor. Pd catalyst was prepared via dry impregnation using palladium acetylacetonate precursor solution in toluene. Several catalyst loadings were impregnated on five different CNF-layer thicknesses in the range 10–20 μm: for all loadings a relatively large average Pd particle size of ∼8 nm was obtained. The lateral and axial distribution of these metallic nanoparticles was uniform across the support for CNF-layer thicknesses up to 13 μm. For larger thicknesses, the presence of a dense carbonaceous layer underneath the open CNF-layer negatively affects the accessibility for Pd nanoparticles, resulting in a less good lateral distribution. External and internal mass transfer properties were evaluated, by carrying out hydrogenation of nitrite ions in aqueous phase. For sufficiently thin CNF-layers (⩽13 μm) hydrogenation was under kinetic control, indicating absence of mass transfer limitations and thus good accessibility and performance of the Pd containing CNF layers for reactant species.

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► Synthesis of well-defined and adhesive carbon nanofiber layers in Si-based microreactors.
► Deposition of Pd on CNF layers and testing aqueous phase nitrite removal by catalytic reduction.
► Microreactors with CNF-layers of ∼13 μm thickness exhibited best catalytic performance.