稻壳灰高值利用制备ZSM-5分子筛

ZSM-5 Zeolite Production Using Rice Husk Ash

以稻壳灰制备的硅溶胶为硅源,采用水热合成法制备ZSM-5分子筛。通过XRD、SEM、ICP及XRF等测试手段,系统考察反应时间、模板剂(TPABr)用量及未加铝源对ZSM-5分子筛形貌、结晶度及合成残液组成的影响。结果表明:当反应时间达到10~12 h,反应物料基本完全进入分子筛中,继续延长反应时间,虽能进一步促进物料反应和提高产品结晶度,但同样会造成分子筛颗粒增大和单位能耗增加;随模板剂用量的减少(Si O2/TPABr=0.05、0.04和0.01),分子筛结晶度逐渐降低(89.41%、81.97%和69.77%),但分子筛的形貌、颗粒大小及产率并没有明显变化;由于稻壳灰本身特性,制备的硅溶胶含有一定量的铝(0.0143%),在未外加铝源的情况下可成功制备出ZSM-5分子筛,且分子筛的形貌、结晶度及产率均未受到明显影响。

ZSM-5 molecular sieves were synthesized by hydrothermal crystallization, using the rice husk ash（RHA） ludox as the Si resource. The effect of hydrothermal reaction time, the template content in the solution and without adding Al resource on the resulting zeolites and residual liquid were investigated, which were characterized by XRD, SEM, ICP and XRF. The results showed that most of the reactants were synthesized into ZSM-5 molecular sieves when the reaction time was 10 ~ 12 h. When the reaction time exceeded 12 h, some of the rest reactants continued to participate in the synthesis, and the crystallinity of the zeolites was improved, while the size of crystal and unit energy consumption increased. When the content of template reduced（Si O2/TPABr = 0.05, 0.04 and 0.01）, the crystallinity of the zeolites decreased（89.41%, 81.97% and 69.77%）, while little changes of morphology, size and productivity of the crystals were found. The morphology, size and productivity of the synthesized ZSM-5 molecular sieves without adding Al resource did not change significantly, due to the RHA ludox contained certain amount of Al element which derived from the rice husk ash.