甲烷干重整反应用Ni-Ru/MgAl类水滑石催化剂的研究

采用焙烧记忆法分别制备Ni/Mg Al O和NiRu/Mg Al O类水滑石催化剂用于甲烷干重整反应.利用XRD、TPR、TG、XPS、CO2-TPD、TEM等表征催化剂的结构及失活特征,发现在Ni/Mg Al O中添加Ru,有利于增加催化剂表面Ni含量,并促进Ni2+的还原.不同Mg/Al比双金属催化剂中,7Ni-0.15Ru/Mg2.5Al催化剂具有较高的催化活性,这归结为该催化剂适宜的碱性、较高表面Ni含量以及小尺寸的Ni0物种.添加Ru明显抑制Ni/Mg Al O催化剂表面的丝状碳的形成.而7Ni-0.15Ru/Mg2.5Al较强的抗积碳性能与其较小Ni0晶粒尺寸及适宜催化剂碱性有关.     

Effect of the oxidizing capacity of ceria-based support on the conversion of methane to syngas

Ceria-based solid solutions have been proposed as catalytic supports for the conversion of methane to syngas. Control of oxygen vacancies in vacancy-rich oxides represents a promising way to stable catalysts with improved activity.     

Interaction between dry granular materials and an inclined plate (comparison between large-scale DEM simulation and three-dimensional wedge model)

The interaction between dry granular materials and an inclined plate is numerically studied using a three-dimensional discrete element method (DEM) simulation. In the simulation, a plate is dragged horizontally through densely packed dry granular materials. To examine the effect of the rake angle α of the plate on the drag force acting on the plate, three cases with α = 50°, 70°, and 90° are compared (α = 90° for a vertical plate). The results show that for all cases, the force oscillates as the plate advances. As α decreases, the amplitude and frequency of the force oscillation decrease and increase, respectively. The force oscillation is attributed to the periodic evolution of a shear band formed in the materials. The relationships between the rake angle, evolution of the shear band, and drag force can be explained quantitatively by using a three-dimensional wedge model considering the variation of the local volume fraction inside the shear band.