Ni-ZSM-5 and Cu-ZSM-5 synthesized directly from aqueous fluoride gels

Ni-ZSM-5 and Cu-ZSM-5 have been synthesized in a slightly acidic fluoride m edium. A low water H-ZSM-5 formula was used to synthesize the metal-substit uted systems using bis(tetraethylammonium) tetrachloronickelate(II) [N(CH2C H3)(4)](2) [NiCl4] and bis(tetraethylammonium) tetrachlorocuprate(II) [N(CH 2CH3)(4)](2) [CuCl4] as the tetrahedrally coordinated metal species. X-ray diffraction analysis established the presence of highly crystalline and the rmally stable material. Unit cell dimensions increased with increasing leve ls of metal substitution. X-ray fluorescence (XRF) bulk analysis showed inc reasing levels of metals in the material and corresponding decreases in the moles of silica. The maximum levels of substitution achieved were Ni 3.93 and Cu 4.38 (in wt %). Analysis by scanning electron microscopy (SEM) showe d a crystal morphology similar to that of H-ZSM-5 but with smaller crystals having an increasing aspect ratio in the substituted materials. There was evidence of twinned crystals and the appearance of raised faces in all subs tituted samples. Thermogravimetric and derivative thermogravimetric analysi s showed anomalous losses, which could be explained by Jahn-Teller distorti ons. Fourier transform infrared analysis of the materials showed an increas ing level of distortion in significant regions of the spectra. Analysis of the filtrate, from EDTA-exchanged material, by atomic absorbance spectrosco py (AAS) showed that there were tetrahedrally coordinated M2+ species in th e material and relatively small amounts were removed by ion exchange.