In packed columns, the carrier gas percolates through the porous bed. In a packed column, separation is achieved by moving the solutes apart. Packed columns are made up of two main materials; stainless steel and Pyrex glass. Metal packed columns are more suitable for long and high carrier gas flow rates to tolerate the elevated pressures. Molecular sieves are three-dimensional framework structure that forms pores of molecular dimensions. The pores adsorb molecules which fit closely inside the pores and exclude molecules that are large. Zeolites are subset of molecular sieves. Molecular sieves are used as adsorbents, gas separations, oil refining and many diverse areas. X-ray diffraction, transmission electron microscopy, and pore size analysis confirmed that molecular sieves consisted of a three-dimensional regular array of uniform mesopores which was 3 nm in diameter.