Effect of synthesis time on morphology of CeO2 nanoparticles and Au/CeO2 and their activity in oxidative steam reforming of methanol

Ceria(CeO2)supports,synthesized by hydrothermal treatment with different synthesis time(CeO2-X h,where X is the synthesis time in h)in the presence of the surfactant cetyltrimethyl ammonium bromide,were used as supports for gold(Au)catalysts.The synthesis time significantly affects the morphological structure and crystallite size of CeO2,where CeO2-2 h has the smallest crystallite size with coexisting nanorods and nanoparticles.Transmission electron microscopy analysis confirms the morphology of CeO2 with distinctive(110),(100)and(111)planes,in agreement with interplanar spacings of 0.19,0,27 and 0.31,respectively.However,the morphology of CeO2-8 h and CeO2-48 h is mainly a truncated octahedral with crystal planes(111)and(100)accompanied by an interplanar spacing of 0.31 and0.27 nm,respectively.The CeO2-X h supports and those with a 3 wt%Au loading(Au/CeO2-X h)were investigated in the oxidative steam reforming of methanol at temperatures between 200 and 400℃.The Au/CeO2-2 h gave the highest methanol conversion level and hydrogen yield at a low temperature of 250℃.This superior catalytic performance results from the good interaction between the metal and support and the well-distributed Au species on the CeO2 support.

Physicochemical characterization of forest and sugarcane leaf combustion’s particulate matters using electron microscopy,EDS,XRD and TGA

Physical characteristics and quantitative elemental composition of PM and residual ash produced from sugarcane leaves(SCL)combustion were investigated using TEM-EDS compared with forest leaves(FRL).SEM-EDS was used to analyze the microstructure and chemical composition of biomass raw leaves and PM.XRD analysis was also performed to investigate the characterization of the crystalline nanostructure,structure of PM,and residual ash compared to the TEM image processing method.The oxidation kinetics of biomass raw materials,PM,and residual ash were investigated by TGA.The morphology of fine and ultrafine agglomerate structure of SCL soot and residual ash are not significantly different from the FRL soot and residual ash.The average diameter sizes of single primary nanoparticles of SCL and FRL soot are approximately 37 nm and 35 nm,while the sizes of residual ash are about 18 nm and 22 nm,respectively.The single primary nanoparticles of soot are mainly composed of curve line crystallites of carbon fringes,while residual ash is composed of straightline lattice fringes.The average fringe lengths of SCL and FRL soot are about 1.25 nm and 1.04 nm from the outer shell and 0.89 nm and 0.74 nm from the inner core.The interlayer spacing of curve line carbon fringes of SCL and FRL soot is approximately 0.359 nm and 0.362 nm by the TEM image analysis and it was matched with XRD analysis.The biomass PMs are mainly composed of soot,Si,Ca,and K compounds:SiO_(2),CaCO3,and KCl.