EXAFS studies of iron-substituted zeolite ZSM-5

Extended X-ray absorption fine structure confirms the substitution of Si by Fe in the framework of zeolite ZSM-5. Each framework Fe atom is coordinated to four oxygens with an Fe—O distance of 1.83 Å, and to four Si atoms in the second coordination shell: two at 3.2 Å and two at 3.38 Å from Fe, compared with an average Si—Si distance in silicalite of 3.1 Å. The distances between the framework Fe atom and some of the atoms in the template molecule are determined here for the first time.