Pd/MCM-41对乙醇汽油车尾气排放乙醛的吸附和催化氧化性能

Adsorption and catalytic oxidation properties of Pd/MCM-41 for acetaldehyde in gasohol exhausts

以正硅酸乙酯(TEOS)为硅源,十六烷基三甲基溴化铵(CTAB)为模板剂,采用水热合成法制备了MCM-41分子筛,以其为载体采用等体积浸渍法制得Pd/MCM-41催化剂,并用于乙醇汽油车冷启动排放乙醛的净化。采用氮气吸附脱附法(BET)、X射线衍射仪(XRD)、透射电子显微镜(TEM)对Pd/MCM-41理化性能进行表征,并用原位傅里叶变换红外技术研究了Pd/MCM-41在空气氛围下对乙醛的净化机理。结果表明:Pd/MCM-41具有规整的六方孔道、孔径分布均匀、比表面积大的特点;常温下,Pd/MCM-41催化剂可快速吸附乙醛,吸附容量可达105 mg·g^(-1),而吸附在Pd/MCM-41上的乙醛在180~220℃之间即可发生氧化而生成CO2和乙酸。

MCM-41 is synthesized by hydrothermal method using tetraethyl orthosilicate（TEOS） and cetyltrimethyl ammonium bromide（CTAB） as silicon source and template respectively in the present work. At the same time,Pd/MCM-41 is prepared by impregnation using the obtained MCM-41 as support and applied in the adsorption and catalytic oxidation of acetaldehyde in gasohol exhausts. The physicochemical properties of Pd/MCM-41 are characterized by BET, XRD and TEM, respectively. And in-situ FT-IR technology is adopted to evaluate acetaldehyde adsorption and catalytic oxidation properties on Pd/MCM-41 catalyst under air atmosphere. The results show that Pd/MCM-41 exhibits uniform hexagonal channels with a large specific surface area. And the obtained Pd/MCM-41 catalyst can rapidly adsorb acetaldehyde with an adsorption capacity of about 105 mg·g^（-1） at room temperature. Meanwhile, acetaldehyde adsorbed on Pd/MCM-41 can be easily oxidized to CO2 and acetic acid at 180 to 220 ℃ in air atmosphere.