Pore size engineering of silicates has always been a critical issue in the field of mesoporous materials design. A new method for obtaining silicates with pore sizes up to 11 nm and narrow pore size distributions is described by the authors. Treating non-calcined MCM-41 silicate in aqueous emulsions of long-chain alkylamines, they generated these materials with large pores and exceptionally high pore volumes. Direct synthesis in the presence of long-chain alkylamines affords materials with up to 8 nm pores. These simple techniques are thought to be applicable to other molecular sieves.