Telah dilakukan penelitian pengaruh zirconium dalam perbaikan stabilitas silika molecular sieve dalam larutan basa. Struktur molecular sieve yang dibuat adalah hexagonal MCM-41 yang memiliki luas permukaan 1200 m2/g. Pembuatan bahan silika MCM-41 dilakukan menggunakan campuran larutan cethyltrimetilammonium bromida (CTAB), tetraethylorthosilikat (TEOS), natrium hidroksida (NaOH) dan aquades (H2O) dengan perbandingan molar 0,05 : 1,0 : 0,5 : 100. Adapun penambahan zirconium isopropoksida (ZrPr) sejumlah 3% berat terhadap tetraethylorhosilikat. Penambahan zirconium pada MCM-41 tidak merubah karakteristik distribusi ukuran pori, diameter pori rata-rata sekitar 2 nm dengan luas permukaan mencapai 1200 m2/g. Dengan penambahan 3% berat ZrPr dapat meningkatkan stabilitas silika molecular sieve pada larutan basa. Pengamatan struktur dilakukan dengan X-ray diffraction. Karakteristik pori dianalisis dengan metode physisorption menggunakan nitrogen pada 44 K.Kata Kunci : Zircorium, Molecular Sieve, diameter poriAbstractHas conducted research on the effect of zirconium silica molecular sieve improved stability in alkaline solution . Molecular sieve structure is made of hexagonal MCM - 41 which has a surface area of 1200 m2 / g . Preparation of MCM - 41 silica materials was conducted using a mixed solution of cethyltrimetilammonium bromide ( CTAB ) , tetraethylorthosilikat ( TEOS ) , sodium hydroxide ( NaOH ) and distilled water ( H2O ) with a molar ratio of 0.05 : 1.0 : 0.5 : 100 . As for the addition of zirconium isopropoxide ( ZrPr ) a 3 % by weight of the tetraethylorhosilikat . The addition of zirconium in the MCM - 41 does not alter the characteristics of the pore size distribution , average pore diameter of about 2 nm with a surface area to 1200 m2 / g . With the addition of 3 wt% silica ZrPr can increase the stability of molecular sieve in an alkaline solution . Observation of the structure is done with X - ray diffraction . Pore characteristics were analyzed by the method using nitrogen physisorption at 44 K.Keywords : Zircorium , Molecular Sieve , Pore diameter