Preparation of MnCo/MCM-41 catalysts with high performance for chlorobenzene combustion

MCM-41 was synthesized by a soft template technique.The specific surface area and pore volume of the MCM-41 were 805.9 m2/g and 0.795 cm3/g,respectively.MCM-41-supported manganese and cobalt oxide catalysts were prepared by an impregnation method.The energy dispersive X-ray spectroscopy clearly confirmed the existence of Mn,Co,and O,which indicated the successful loading of the active components on the surface of MCM-41.The structure and function of the catalysts were changed by modulating the molar ratio of manganese to cobalt.The 10%MnCo(6:1)/MCM-41(Mn/Co molar ratio is 6:1)catalyst displayed the best catalytic activity according to the activity evaluation experiments,and chlorobenzene(1000 ppm)was totally decomposed at 270°C.The high activity correlated with a high dispersion of the oxides and was attributed to the exposure of more active sites,which was demonstrated by X-ray diffraction and high-resolution transmission electron microscopy.The strong interactions between MnO2,Co3O4,MnCoOx,and MCM-41 indicated that cobalt promoted the redox cycles of the manganese system.The bimetal-oxide-based catalyst showed better catalytic activity than that of the single metal oxide catalysts,which was further confirmed by H2 temperature-programmed reduction.Chlorobenzene temperature-programmed desorption results showed that 10%MnCo(6:1)/MCM-41 had higher adsorption strength for chlorobenzene than that of single metal catalysts.And stronger adsorption was beneficial for combustion of chlorobenzene.Furthermore,10%MnCo(6:1)/MCM-41 was not deactivated during a continuous reaction for 1000 h at 260°C and displayed good resistance to water and benzene,which indicated that the catalyst could be used in a wide range of applications.

Recent Advances in Flame Tomography

To reduce greenhouse gas emissions from fossil fuel fired power plants,a range of new combustion technologies are being developed or refined,including oxy-fuel combustion,co-firing biomass with coal and fluidized bed combustion.Flame characteristics under such combustion conditions are expected to be different from those in normal air fired combustion processes.Quantified flame characteristics such as temperature distribution,oscillation frequency,and ignition volume play an important part in the optimized design and operation of the environmentally friendly power generation systems.However,it is challenging to obtain such flame characteristics particularly through a three-dimensional and non-intrusive means.Various tomography methods have been proposed to visualize and characterize flames,including passive optical tomography,laser based tomography,and electrical tomography.This paper identifies the challenges in flame tomography and reviews existing techniques for the quantitative characterization of flames.Future trends in flame tomography for industrial applications are discussed.

Flexible fuel engine based on multi-combustion control technologies

A combustion control strategy is proposed for diesel engine to reduce PM and NOx emissions significantly, which adopts some technologies including internal exhaust gas recirculation (EGR), split spray, adjustable fuel delivery advance angle and the application of alternative fuels. Based on this strategy, a flexible fuel engine has been developed. The experimental results show that this engine can be fueled with diesel fuel, alcohol, dimethyl carbonate (DMC), etc. It works with extremely low levels of particulate matter (PM) and NOx, 2~3% higher effective thermal efficiency on moderate and high loads when alternative fuels are used. This engine not only has lower exhaust emissions, but also can be fueled with those alternative fuels, which are difficult to be ignited by compression.