Aerosol synthesis of nanoporous silica particles with controlled pore size distribution

• Spherical porous silica particles successfully synthesized by an aerosol-based process with simple template.
• Pore size tailored by amounts of templates added and by varying silica particle size.
• Catalyst for Fischer–Tropsch-synthesis prepared by spray drying of SiO2/Co3O4/PVP suspension.

Spherical porous silica particles with well-defined mesoscopic pore structures were synthesized by spray drying of nanocolloidal SiO2, using polyvinylpyrrolidone (PVP) as pore template. During droplet drying, the surface tension of the water leads to spherical close-packed agglomerates of PVP coated silica nanoparticles. After removal of the PVP by calcination, well-defined porous particles were obtained which were characterized by SEM, TEM and nitrogen adsorption–desorption isotherms. Pore size distribution and porosity could be tailored by using colloidal nanosuspensions with different silica particle sizes and by adding different amounts of template (PVP) into the colloidal silica solution. By adding Co3O4 nanoparticles as active phase into the starting suspension, porous catalytic particles were produced by spray drying and calcination. These particles, after reduction to metallic cobalt, are intended to be used as catalyst for the Fischer–Tropsch synthesis, where the product selectivity can be adjusted by tuning the pore size distribution.