The structure of ZSM-5

ZSM-5 was synthesized by Argauer and Landolt in 1972. This is a medium pore zeolite with channels defined by ten-membered rings. The synthesis involves three different solutions. The first solution is the ion source of alumina, sodium ions and hydroxide; in the presence of excess base of the alumina will form soluble Al (OH) 4 - ions. The second solution has the tetrapropylammonium cations which acts as a templating agent. The third solution is the source of silica, one of the modules to the basic frame structure of a zeolite. Mix the three solutions produces supersaturated tetrapropylammonium ZSM-5, which can be heated to produce a solid and recrystallize. ZSM-5 is composed of several units connected together by pentasil ribs b oxygen to form pentasil chains. Pentasil unit consists of eight five-membered rings. In these rings, the peaks are Al or Si and O is assumed to be stuck between the peaks. Pentasil chains are linked together by oxygen bridges to form rings corrugated sheets with 10 holes. As the pentasil units, each hole has 10-ring as Al or Si peaks with a joint supposed to be glued between each vertex. Each corrugated sheet is connected by oxygen bridges to form a structure with "10 cyclic straight channels parallel to the sinusoidal undulations cyclic and 10 channels perpendicular to the leaves." sheets adjacent layers are connected by a reversal point. The pore size estimated channel extending parallel to the corrugations is 5.4 to 5.6 Å.  The crystallographic unit cell of ZSM-5 has 96 sites T (Si or Al), O 192 locations and a number of compensating cations depending on the Si / Al ratio ranging from 12 to infinity. The orthorhombic structure (space group Pnma) at elevated temperatures, but a phase transition to the space group monoclinic P21/n.1.13 occurs upon cooling below a transition temperature, lies between 300 and 350 K.
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