Effect of Preparation Methods on Activation of Catalysts BaNi_(0.2)Mn_(0.8)Al_(11)O_(19-δ) for Dimethyl Ether Combustion

摘要

Catalytic combustion of dimethyl ether (DME) over hexaaluminate catalyst BaNi_(0.2)Mn_(0.8)Al_(11)O_(19-δ) has been investigated.The catalysts were prepared with the sol-gel method and reverse microemulsion method respectively and characterized by thermogravimetry-differential thermal analysis,X-ray diffraction and transimission electron microscope.It was found that the formation of Mn,Ni modified hexaaluminate was a relatively slow process via two solid state reactions and spinel structure was a transition phase.At the same calcined temperature and time,the catalyst prepared with the reverse microemulsion method could form the hexaaluminate phase more easily than that prepared with the sol-gel method.The catalyst BaNi_(0.2)Mn_(0.8)Al_(11)O_(19-δ) prepared with the reverse micro-emulsion method appeared a plate-like morphology,while it appeared a needle-like morphology when using the sol-gel method.The catalytic activities of catalysts BaNi_(0.2)Mn_(0.8)Al_(11)O_(19-δ) prepared with two different methods for DME combustion were tested.It showed that catalyst prepared with the reverse microemulsion method had better catalytic activity,i.e.T_(10%) of DME had decreased by 45°C,about 90% conversion of diemthyl ether at 380°C.