Immobilization of carbon composite materials on structured frameworks for application in continuous catalytic experiments: Application in NO3- conversion

Bimetallic catalysts applied for water treatment are highly susceptible to deactivation/poisoning mainly when immobilized in macroscopic structures. Metal support interaction characteristic of metal oxides/composite supports emerges as an important strategy for controlling this phenomenon. This work explores a novel washcoating methodology to synthesize macrostructured composite catalysts for selective nitrate reduction. This approach allowed to effectively integrate powder composite materials into macroscopic frameworks, allowing to take advantage of modifications performed in the powder materials, often associated with increased catalytic activity/selectivity. Pd-Cu composite materials (metal oxides with carbon nanotubes) were prepared/tested for nitrate conversion. Titanium dioxide composites achieved the best performance (54 % nitrate conversion and 61 % N 2 selectivity), outperforming the results obtained with more conventional synthesis methodologies. The catalysts proved to be highly active and resistant over several hours of reaction. This is a pioneering work focused on the synthesis and application of macrostructured composite catalysts in G-L-S (gas-liquid-solid) treatment systems. • Metal oxides:CNT composites were tested as support for bimetallic catalysts. • Composite supports allowed high nitrate conversion without compromising selectivity. • Washcoating procedure allowed the synthesis of stable/active structured catalysts. • Composite materials were adequately incorporated on cordierite support. • High nitrate conversions outperforming most established synthesis techniques.