The deposition of NH 4 HSO 4 on catalysts is one of the key issues for selective catalytic reduction of NO x . In this study, NH 4 HSO 4 was preloaded on catalysts, and the effects of MoO 3 and CeO 2 doping on the decomposition and reactivity of NH 4 HSO 4 on V 2 O 5 /TiO 2 catalysts are studied. The results show that the introduction of MoO 3 and CeO 2 significantly promoted NO x conversion on the V 2 O 5 /TiO 2 catalysts. Doping with MoO 3 could effectively enhance the S and H 2 O resistance of the catalysts. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis indicate that it is the strong chemical interactions between NH 4 HSO 4 and the catalysts that are adverse to the decomposition of NH 4 HSO 4 . However, doping with MoO 3 apparently inhibits these interactions, which significantly decrease the decomposition temperature of NH 4 HSO 4 . In situ FTIR experiments show that the NH 4 + in preloaded NH 4 HSO 4 could react with gaseous NO on catalysts, and doping with MoO 3 could facilitate the reaction rate.
Jin-Bo Cheng,Yan-Qin Wang,Ai-Ning Zhang,Hai-Bo Zhao,Yu-Zhong Wang
Nowadays, there is an urgent need for microwave absorbing materials with light weight, thin thickness, and strong absorbing ability to solve the problem of electromagnetic radiation. In this study, we report a novel high-performance aerogel absorber by growing MoO 3 -doped WO 3 nanoflakes on reduced graphene oxide (rGO) sheets. The resultant rGO-Mo-WO 3 aerogel displays a low density (∼75 mg/cm 3 ) and unique hierarchical architectures including 3D porous microstructures, 2D rGO skeleton, and binary transition metal oxide of Mo-WO 3 nanoflakes, thus leading to excellent microwave absorption performances . Typically, rGO-Mo-WO 3 aerogel exhibits an ultra-strong reflection loss (RL) of −61.8 dB with a thin coating thickness of 1.54 mm. And a wide effective absorption bandwidth of 6.24 GHz can be achieved at a low filler loading of 8 wt%, much superior to previous ones. The synergistic effect of moderate polarization relaxation loss and weak conduction loss together with the porous microstructure for the aerogel result in the suitable impedance matching and strong microwave attenuation ability. This work may demonstrate a promising method to fabricate hierarchically nanostructured absorbers with the advantages of light weight, ultra-strong microwave absorption, and thin coating thickness.
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