New Synthesis
of ZSM‑5 from High-Silica Kaolinite
and Its Use in Vapor-Phase Conversion of 1‑Phenylethanol to
Styrene
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Abstract
The present work describes the utilization
of high-silica kaolinite
for the synthesis of zeolite ZSM-5 with different SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> ratios. The new synthetic method, which involves
acid–base activation of metakaolinite, is most suitable for
the production of high-silica zeolites. The process starts with the
conversion of kaolinite to metakaolinite, which is then dealuminated
with sulfuric acid with varying concentrations. A relationship between
the acid concentration and the SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> ratio in the final product was established. The dealuminated
kaolinite was hydrothermally treated with alkali to obtain phase-pure
ZSM-5. The zeolites were characterized by XRF, XRD, SEM, and N<sub>2</sub> physisorption. The sodium form of the zeolite was converted
to the acid form for application in catalytic dehydration of alcohols.
The catalytic activity of the zeolite was tested in the dehydration
of 1-phenylethanol into styrene. The results reveal a selective formation
of styrene in high yield that reaches up to 95%
