| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 105 === In this study we focus on designing HZSM-5 (Si/Al ratio = 11.5) in methanol aromatization. The first part is to explore the synergistic effect of disilication and Ga doping in HZSM-5. Desilication not only increases mesoporisity and reduces mass transfer resistance, but also enhances Brønsted acidity. In addition, gallium precursor, (Ga(NO3)3 6H2O), is easier to diffuse into HZSM-5 cavities and contacts with Brønsted acid to form cyclodehydrogenation center compared to its pristine counterpart. Ga-doped, desilicated HZSM-5 (Ga-AT0.01) has maximum aromatics selectivity at 500℃.
The second part of this work is to synthesize Ga-doped, desilicated HZSM-5 with systematically increased alkalinity. Enhancing alkalinity in desilicatoin can improve the amounts of (GaO)+-Brønsted acid site. However, severe alkalinity can destroyed HZSM-5 structure (AT-0.2). This leads Ga/AT-0.05 to be an optimal MTA catalyst.
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