微波辅助双模板剂体系快速合成纳米SSZ-13分子筛及NH3-SCR脱硝性能研究

Rapid synthesis of nano SSZ-13 molecular sieve by microwave-assisted dual-template system and study on its performance in NH_(3)-SCR denitration

采用硅溶胶为硅源、偏铝酸钠为铝源、四甲基氢氧化铵(TMAOH)和N,N,N-三甲基金刚烷氢氧化铵(TMAdaOH)为混合模板剂,通过微波加热方式在8 h内快速合成结晶度良好的纳米SSZ-13分子筛。结合XRD和SEM理化性质表征,考察了微波辅助晶化时间、晶化温度、初始凝胶中TMAdaOH用量、硅源和铝源类型等因素对合成SSZ-13分子筛的影响,进一步通过离子交换的方式负载铜离子制备Cu-SSZ-13催化剂。结果表明,在中低温(175~350℃)区域NOx转化率达99%,NH3-SCR脱硝性能满足中低温脱硝催化剂的要求。

Nano SSZ-13,a molecular sieve with high crystallinity,is successfully synthesized within 8 hours via microwave heating method by using silica gel as silicon source,sodium meta-aluminate as aluminum source and a mixture of tetramethylammonium hydroxide(TMAOH)and N,N,N-trimethyl-1-adamantammonium hydroxide(TMAdaOH)as mixed template.The influences of key factors such as microwave-assisted crystallization time,crystallization temperature,the using amount of TMAdaOH,different types of silicon and aluminum on the relative crystallinity and morphology features of SSZ-13 are investigated in detail through characterization by X-ray diffraction and scanning electron microscope.Furthermore,Cu-SSZ-13 catalyst is prepared by loading copper ions through ion-exchange onto SSZ-13.It is shown that the conversion of NOx over the prepared Cu-SSZ-13 catalyst can reach 99%in the medium-low temperature range(175-350℃),which totally meets the needs for low temperature denitration catalyst.