Maya crude hydrodemetallization and hydrodesulfurization catalysts: An effect of TiO2 incorporation in Al2O3

Hydrotreating of Maya heavy crude oil over high specific surface area CoMo/TiO₂–Al₂O₃ oxide supported catalysts was studied in an integral reactor close to industrial practice. Activity studies were carried out with Maya crude hydrodesulfurization (HDS), hydrodemetallization (HDM), hydrodenitrogenation (HDN), and hydrodeasphaltenization (HDAs) reactions. The effect of support composition, the method of TiO₂ incorporation, and the catalyst deactivation are examined. Supported catalysts are characterized by BET specific surface area (SSA), pore volume (PV), pore size distribution (PSD), and atomic absorption. It has been found that sulfided catalysts showed a wide range of activity variation with TiO₂ incorporation into the alumina, which confirmed that molybdenum sulfided active phases strongly depend on the nature of support. The pore diameter and nature of the active site for HDS, HDM, HDN, and HDAs account for the influence of the large reactant molecules restricted diffusion into the pore, and/or the decrease in the number of active sites due to the MoS₂ phases buried with time-on-stream. The textural properties and hysteresis loop area of supported and spent catalysts indicated that catalysts were deactivated at the pore mouth due to the metal and carbon depositions. The atomic absorption results agreed well regarding the textural properties of spent catalysts. Thus, incorporation of TiO₂ with γ-Al₂O₃ alters the nature of active metal interaction with support, which may facilitate the dispersion of active phases on the support surface. Therefore, the TiO₂ counterpart plays a promoting role to HDS activity due to the favorable morphology of MoS₂ phases and metal support interaction.     

Effect of phosphorus on activity of hydrotreating catalyst of Maya heavy crude

The effect of phosphorus on physical properties of the catalyst and on activity of hydrotreating of Maya crude was studied in this work. Catalysts were prepared by the co-impregnation method. Alumina-titania binary oxide was used as a support material. The presence of phosphorus in the catalyst decreases the percentage of micropores, and it results in a decrease of specific surface area. Temperature program reduction (TPR) shows that phosphates reduce metal support interaction. It leads to the formation of polymolybdate phases in expense of strongly bonded tetrahedral molybdates. At higher P loading, polymolybdates may be present with quasi crystalline MoO₃. However, the TPR experiment is not sufficiently sensitive to distinguish several phases present on the catalysts used by the authors. A slight increment of HDM activity is observed, but HDS activity is lower in the P containing catalyst compared with the P free catalyst. The changes of physical properties of the spent catalysts are mainly due to the coke formation on the catalyst. The presence of phosphorus on hydrotreating catalysts inhibits coke formation during the hydrotreating reaction.     

三维动画Episode的设计与制作

随着计算机处理图形图像的技术日益完善,CG制作越来越频繁地出现在生活中,其中的三维动画尤为常见。Maya是现在国际最为流行的顶级三维动画制作软件。通过Episode动画短片的制作,介绍运用Maya制作三维动画的步骤和过程。     

基于Maya的人物角色行走运动的设计

阐述在Maya软件中制作人物角色行走的流程以及一些相关注意事项。通过分析人体行走过程的重要特征,详细论述人物角色行走动画的制作过程,探讨Maya技术在人物角色行走动画中的应用技巧。     

MAYA中的矩阵运用

矩阵已作为一种常用的数学表示方法被普遍地运用在三维动画领域中,然而大多数线性代数书籍中关于矩阵的描述都是基于普遍性的数学概念的介绍,这种矩阵对于很多三维动画从业人员来说,还较难理解.旨在通过使用Maya,对矩阵这个数学概念在三维动画中担当的角色以及其作用进行简单说明,以提供给三维动画制作者一个易懂易用的参考.     

浅谈Maya动画制作流程

结合作者的教学与工作实际,本文简要讲述了在Maya软件中制作动画的基本流程以及一些注意事项。     

基于 Maya 的水墨效果实现

传统的水墨动画是中国艺术史上的一大创举,但因制作手法复杂,作品数量少之又少,逐渐出现衰败的迹象,随着计算机软件技术的飞速发展,以数字化技术手段进行水墨动画的创作似乎又给中国水墨动画带来了一线生机,也是未来水墨动画发展的必然趋势,本文基于Autodesk公司的Maya软件,详细介绍了制作水墨荷花的方法.     

大规模刚体碰撞模拟技术在电影后期特效中的开发与应用(下)

随着科技的发展,计算机图形学的广泛应用,电影后期制作的新方法层出不穷,在很大程度上提高了中国电影制作水平。近些年来,以并行运算为主的新硬件得到了快速发展,对应的并行算法也随之衍生;并行运算在降低运算成本的基础上更提高了运算效率。运算效率的提高和新物理模拟引擎的诞生使大规模刚体碰撞模拟成为现实,能够在电影后期制作过程中创作出过去难以想象的超现实模拟镜头,对进一步提高中国电影后期制作水平、丰富电影制作手段有很大的推动作用。     

大规模刚体碰撞模拟技术在电影后期特效中的开发与应用(上)

随着科技的发展,计算机图形学的广泛应用,电影后期制作的新方法层出不穷,在很大程度上提高了中国电影制作水平。近些年来,以并行运算为主的新硬件得到了快速发展,对应的并行算法也随之衍生;并行运算在降低运算成本的基础上更提高了运算效率。运算效率的提高和新物理模拟引擎的诞生使大规模刚体碰撞模拟成为现实,能够在电影后期制作过程中创作出过去难以想象的超现实模拟镜头,对进一步提高中国电影后期制作水平、丰富电影制作手段有很大的推动作用。     

基于Mel Script的人眼随机眨动行为仿真研究

为说明如何用Maya Mel Script脚本语言对人眼随机眨动行为进行仿真；文章分析了人眼眨动的行为规律，说明了在Maya中对眼睛的骨骼绑定和封装技术，以及利用独立于动画时间线和关键帧编辑模式的Mel Script动画技术模拟人眼的随机眨动行为。并讨论了Blendshape技术和骨骼绑定结合Mel Script动画技术在动画效果上的优劣。结果证明基于Mel Script的人眼随机眨动行为仿真是可行的，可以节省动画制作时间。