Cu-SSZ-13/碳化硅废料复合材料的合成及其NH3-SCR性能研究

Cu-SSZ-13/SiC-waste Composite: Synthesis and Application for NH3-SCR

太阳能电池硅片切割工艺中使用碳化硅作为切割硅片的磨料,切割后会形成大量的废料-一种碳化硅基混合物(HT-SiC),其中含有少量金属等杂质。本工作开发了一种新型催化剂,将Cu-SSZ-13分子筛和HT-SiC通过水热法结合离子交换制备成一种复合材料Cu-SSZ-13/HT-SiC,并应用于脱硝催化反应。在合成Cu-SSZ-13分子筛时使用两种模板剂:N, N, N-三甲基-1-铵金刚烷(TMAdaOH)和铜胺络合物(Cu-TEPA)。实验结果表明,在HT-SiC的参与下, TMAdaOH模板成功得到SSZ-13晶体,而使用Cu-TEPA模板得到的可能是非晶态结构。在NH3-SCR反应中,结果显示, Cu-SSZ-13/HT-SiC在中高温区间相比纯相Cu-SSZ-13更加出色,在500℃时,前者的NO消耗量约为后者的11倍。另外,相比于用纯相SiC(α-SiC)合成的Cu-SSZ-13/α-SiC催化剂, Cu-SSZ-13/HT-SiC在整个温度区间的催化活性表现更佳。这些良好的性能不仅归因于SiC良好的导热性和热稳定性,而且归因于HT-SiC中存在的少量Fe组分,在脱硝催化反应中充当了还原NO的活性位点。该方法不仅解决了废弃磨料环境污染的问题,也为重复利用SiC废料提供了新的途径。

Solar cell wafer cutting process produces a lot of silicon carbide-based waste named HT-SiC. Herein, we developed a novel catalyst through a one-pot hydrothermal process combined with an ion-exchange method to synthesize Cu-SSZ-13/HT-SiC composite and applied in denitration catalytic reaction. TMAdaOH and Cu-TEPA were used as templates to prepare the precursor for Cu-SSZ-13, respectively. Results showed that, with participation of HT-SiC, SSZ-13 crystal was successfully obtained by using TMAdaOH template, while it would get only amorphous structure by using Cu-TEPA template. NH3-SCR(Selective Catalytic Reduction, SCR) exhibited catalytic activity and stability of Cu-SSZ-13/HT-SiC in medium and high temperature zones was more effective than those of Cu-SSZ-13 without HT-SiC, and NO consumption by the former was about 11-fold of the latter at 500 ℃. Moreover, compared with Cu-SSZ-13/α-SiC catalyst prepared with pure SiC(α-SiC), Cu-SSZ-13/HT-SiC shows better catalytic activity in the whole temperature range. These favorable performances are attributed not only to the good thermal conductivity and thermal stability of SiC, but also to the 7.34 wt% Fe component contained in HT-SiC, which acts as an active site for reducing NO in NH3-SCR. This method not only provides a way to reuse the SiC waste, but also enhances denitrification activity of Cu-SSZ-13 in medium and high operating temperature.