镧对磷钒催化剂性能的影响

镧对磷钒催化剂性能的影响李铭岫，王心葵，杨述韬，张志新，刘翠格，周敬来（河北师范学院化学系，石家庄０５００９１；中国科学院山西煤炭化学研究所，太原０３０００１）关键词镧，磷钒催化剂，正丁烷，选择，氧化，顺丁烯二酸酐磷钒系催化剂是正了烷氧化制顺丁烯二酸...     

VPO催化氧化正丁烷反应动力学

VPO催化氧化正丁烷制顺酐是目前唯一实现工业化的低碳烷烃选择氧化反应。本文介绍了VPO催化机理和主要的反应网络,综述了国内外反应动力学的研究进展情况。根据人们对正丁烷氧化反应机理的不断认知及动力学模型的完整性,首次将正丁烷氧化制顺酐反应动力学的发展分为探索期、成型期和拓展期三个时期,并阐释了每个时期的特征和典型模型。探索期特征是仅考虑反应物在催化剂表面的吸附行为,成型期特征是充分考虑了产物对反应的抑制作用,拓展期特征是考虑了催化剂氧化度不断变化的动态过程并将不同氧气形式之间的相互变化引入动态模型中。从时空多尺度角度研究动力学和传递之间的相互作用是正丁烷选择氧化反应动力学下一步的研究重点,也是未来动力学研究的发展方向。     

Hybrid Monte Carlo with adaptive temperature in mixed-canonical ensemble: Efficient conformational analysis of RNA

A hybrid Monte Carlo method with adaptive temperature choice is presented that exactly generates the distribution of a mixed-canonical ensemble composed of two canonical ensembles at low and high temperature. The analysis of resulting Markov chains with the reweighting technique shows an efficient sampling of the canonical distribution at low temperature whereas the high temperature component facilitates conformational transitions, which allows shorter simulation times. The algorithm is tested by comparing analytical and numerical results for the small n-butane molecule before simulations are performed for a triribonucleotide. Sampling the complex multiminima energy landscape of this small RNA segment, we observe enforced crossing of energy barriers. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1689–1697, 1998