A process for preparing a mesoporous silica comprising contacting as starting components (1) a structure-directing template selected from the group consisting of hydrogenated and non-hydrogenated natural vegetable oils, silicone oils, and combinations thereof; (2) water; (3) silica; and, optionally, (4) a structure-directing co-template selected from tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, cetyltrimethylammonium bromide (CTAB), hexadecyltrimethylammonium chloride; hexadecyltrimethylammonium hydroxide hydrate, hexadecyltrimethylammonium p-toluenesulfonate, hexadecyltrimethylammonium bis-sulfonate, poloxamers having a weight average molecular weight ranging from 5,000 to 20,000 Daltons (Da), and combinations thereof; in the substantial absence of an alcohol solvent; under conditions such that a mesoporous silica having an average pore diameter ranging from 50 to 175 angstroms and a pore diameter distribution that, within one standard deviation of its mean, is substantially unimodal, is formed. The product composition may offer preferred use in, for example, gas separations, sensing, water purification, heavy metal removal, and electronics, where its narrower pore diameter distribution increases its selectivity.