Impact of surface loading on catalytic activity of regular and low micropore SBA‐15 in the Knoevenagel condensation

The mesopores of SBA‐15 are well‐suited for immobilizing catalytic aminosilanes for converting substrates for fine chemicals, but these materials have micropores that could impact the observed reaction rate of immobilized catalysts. Materials are synthesized with conventional methods that produce micropores (Regular Micropore SBA‐15; REG) and compared to materials with limited to no micropore volume (NMP SBA‐15). These materials are functionalized with aminosilanes for testing in the Knoevenagel condensation. For low amine loadings, NMP materials have a higher observed reaction rate compared to REG materials, achieving twice the conversion in the same time. As the surface density increases, the reaction rate for NMP materials decreases since organosilane functionalization consumes surface silanols that interact cooperatively with the amine. Regardless of surface density, the NMP materials have higher observed reaction rate than the REG materials. These results demonstrate the importance of reducing micropore volume to create highly active catalytic materials.