Organically doped silver nanoparticles deposited on titania nanofibers: Enhanced catalytic methanol oxidation

Nanometric particles (10-30 nm) of thermally activated Congo-red (CR) entrapped within silver deposited on TiO₂ nanofibers form a new triple hybrid - organic, metallic, and ceramic - catalyst (CR@Ag/TiO ₂-nf). It is shown that the downscaling and the use of nanofibers as supports cause CR@Ag/TiO₂-nf to considerably outperform the unsupported powder CR@Ag as well as the supported undoped Ag/TiO₂-nf catalysts in all of the studied parameters of the industrially important oxidation of methanol to formaldehyde. These parameters include the weight hourly space velocity (WHSV), the space time yield (STY), the reaction conversion, and the reaction selectivity values. Typically, the WHSV shows a huge jump - approximately 18 times higher - compared to unsupported powder; the STY shows a 10-fold increase out of which 25% is achieved due to the CR doping; and the fully activated catalyst (second run) provided a conversion of 98% and selectivity of 85%. The high efficiency of this novel type of triple hybrid catalyst is explained on the basis of structural-morphological characteristics such as higher porosity, larger surface area, and relatively low sinterability of the separated doped silver particles which are provided by the TiO ₂ nanofibers support.