Vol.:(0123456789) 1 3 Catalysis Surveys from Asia https://doi.org/10.1007/s10563-019-09272-6 Infuence of MnO 2 Morphology on the Catalytic Performance of Ag/ MnO 2 for the HCHO Oxidation Suhong Lu 1  · Qinyu Zhu 1  · Yaxin Dong 1  · Yiming Zheng 1  · Xue Wang 1  · Kelun Li 2  · Fenglin Huang 1  · Bo Peng 1  · Yuliang Chen 1 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract A series of Ag/MnO 2 catalysts employing MnO 2 nanorods (MnO 2 -r) and nanoparticles (MnO 2 -n) as the supports were pre- pared by conventional incipient wetness impregnation. Their structures had been characterized by BET, SEM, TEM, XRD, H 2 -TPR, O 2 -TPD and XPS. The catalytic activities in HCHO oxidation had also been investigated. The results showed that MnO 2 -r and MnO 2 -n exhibited diferent reducibility and surface active oxygen. Ag/MnO 2 -r performed better reducibility and more surface active oxygen than that of Ag/MnO 2 -n. It had observed that Ag/MnO 2 -r could achieve complete oxidation of HCHO at 80 °C, due to the low-temperature reducibility and abundant surface active oxygen. Meanwhile, the Ag/MnO 2 -r catalyst exhibited good stability. Keywords Formaldehyde · Catalytic oxidation · Ag · Morphology · MnO 2 1 Introduction Formaldehyde (HCHO) has been considered as a typical pol- lutant to the atmosphere and human health, which is mainly released from consumer products and building/furnishing materials [1]. Long-term exposure to indoor air containing even very low concentrations of HCHO may induce a variety of diseases, such as respiratory, skin irritation, nasal tumors, irritation to eyes and so on [2]. Thus, it is urgent to reduce the indoor HCHO emission in order to meet the strict envi- ronmental regulations. So far, considerable technologies have been made to eliminate HCHO, including adsorption, photo-catalysis, plasma technology and catalytic oxidation methods [3]. Among them, catalytic oxidation of HCHO has been rec- ognized as a promising technique, due to its high efciency, low temperature, simple equipment and no secondary pol- lutant [4]. Therefore, it is the key to develop novel catalyst with efcient activity for the catalytic oxidation of HCHO at low temperature. For decades, the conventional catalysts mainly include the supported noble metal catalysts (Pt, Pd and Au) [5–7] and transition metal oxide catalysts (MnO 2 , Co 3 O 4 and CeO 2 ) [8–10]. Especially, it has been reported that supported Pt catalyst can obtain complete conversion of HCHO at room temperature [5, 11, 12]. However, the high price of precious metals limits their widespread applications. Transition metal oxide catalysts are very cheap, but complete oxidation of HCHO is usually achieved at high temperature (> 100 °C). Thus, it is signifcant and urgent to exploit efcient and low cost catalysts. It has observed that supported Ag catalysts perform some outstanding ability in the reaction of HCHO oxidation [13, 14]. Therefore, Ag may be a promising sub- stitute for catalytic oxidation of HCHO. Manganese oxides have been greatly considered as promising, inexpensive and nontoxic materials in envi- ronmental catalysts, used in HCHO oxidation [15]. Bai et al. [16] prepared three dimensional ordered mesoporous MnO 2 , which obtained complete oxidation of HCHO at 130 °C. Similar catalytic activity over mesoporous silica- confned manganese oxide was also reported by Averlant [17]. It is interesting that manganese oxides with difer- ent morphology have been widely applied as catalysts and shown exciting performance. Shi et al. [18] claimed that * Suhong Lu lusuhong@xsyu.edu.cn 1 College of Chemistry and Chemical Engineering, Xi’an Shiyou University, Xi’an 710065, China 2 Shaanxi Coal and Chemical Technology Institute Co., Ltd, Xi’an 710070, China