 The reason for their success is related to their specific features in converting molecules having kinetic diameter below 1 nm, but they become inadequate when reactants with sizes above the dimensions of the pores have to be processed.Research efforts to synthesize zeolites with larger pore diameter, high structural stability and catalytic activity have not given the expected results yet.The discovery of a new family of mesoporous molecular sieves in the early 1990s by Kuroda et al., known as KSW-1 and FSM-16, and by ExxonMobil, called M41S, opened new possibilities to prepare catalysts for reactions of relatively large molecules.