物理化学实验室真空与气路系统的改进

物理化学实验中,不少实验需要通气体,因此,物理化学实验室气路系统的设计安装具有极其重要的意义。本文针对物理化学实验中所出现的几种气路进行了说明并改进,提高了实验气路系统的可操作性,降低了气体泄漏的可能性,保障了实验室的安全。国家基础科学人才培养基金项目(J1310024);;2016年度教育部“基础学科拔尖学生培养试验计划”研究课题;;2017年福建省本科高校教育教学改革研究项目(FBJG20170295);;2017年度厦门大学教学改革研究项目(JG20170204

氧化镧表面反应性对甲烷和氧分子活化的影响

以氧化镧催化剂在甲烷氧化偶联(OCM)反应中的结构敏感性实验研究为基础,采用周期性密度泛函理论(DFT)计算研究氧化镧(001),(110)和(100) 3个晶面及OCM反应物分子甲烷和氧在其上的吸附、活化和解离...国家自然科学基金(批准号:21373169);; 教育部长江学者和创新团队发展计划项目(批准号:IRT1036)资助~

A computational study of the mechanism for the C6H5+CH2O reaction

The mechanism for the C6H5 + CH2O reaction has been investigated with hybrid density functional quantum-chemical and statistical theory calculations. The results reveal three possible reaction channels: (1) The abstraction reaction producing C6H6 + HCO; (2) addition to the C atom yielding C6H5CH2O and (3) addition to the O atom giving C6H5OCH2. The barriers for these 3 reactions, calculated at the B3LYP/aug-cc-pvtz level of theory using the geometry optimized with B3LYP/cc-pvdz are 0.8, 1.4 and 9.1 kcal mol(-1), respectively. The C6H5CH2O radical can fragment to form C6H5CHO + H with a barrier of 19.4 kcal mol(-1). It can also undergo isomerization reactions via two cyclic epoxy intermediates to give C6H5OCH2 with a maximum barrier of 20.4 kcal mol(-1). Transition-state theory calculations using the predicted energy barriers and structures for the rate constants of the abstraction reaction (1) lead to very good agreement with our recently measured values, while the result of RRKM calculations for the isomerization/decomposition of C6H5OCH2 to C6H5CHO + H also agrees quantitatively with available experimental data

Catalytic Behaviors and Stability of Y_2O_3-Modified Ni/SiO_2 for Partial Oxidation of Methane into Synthesis Gas

采用常规浸渍法制备Y_2O_3修饰的Ni/SiO_2催化剂,并考察其催化甲烷部分氧化(POM)制合成气反应性能。结果表明,Y_2O_3的引入减小了金属Ni的粒径,有效提高了Ni在载体表面的分散性,增强了金属Ni与载体SiO_2间的相互作用,从而使催化剂的抗烧结、抗积碳能力,以及催化剂的POM反应性能得以改善。A series of Y_2O_3-modified Ni SiO_2 catalysts were synthesized by a conventional impregnation method.Catalytic performances for the partial oxidation of methane(POM) to synthesis gas were investigated.The addition of Y_2O_3 promotes a decrease in size of Ni particles supported on silica,increased the dispersion of Ni particles,and enhanced the interaction between Ni and silica.These properties gave the catalysts increased anti-sintering and resistance to carbon deposits.The catalytic behaviors of the Ni-based catalysts for POM were significantly improved when Y_2O_3 was introduced.国家自然科学基金(21373169);; 教育部创新团队项目(IRT1036)资助~

Nb~+离子活化甲烷脱氢反应机理密度泛函(DFT)研究

通过DFT-UB3LYP方法,计算了五重、三重和单重自旋态下的气相Nb+离子活化甲烷脱氢反应的能量变化,并对其直接式和插入式反应机理进行了比较,考察了自旋翻转对反应的影响.结果表明,插入式脱氢较直接式有利,CH4上的H转移到Nb+上形成的中间体HNbCH3+中,多重度由五重降为三重,反应活化能垒显著降低;HNbCH3+可经四中心过渡态转化为(H2)NbCH2+,最后生成三重态的NbCH2++H2.速控步骤为(H2)NbCH2+的脱氢.此外,通过对V+,Nb+,Ta+活化甲烷的比较研究了三者活化甲烷的反应活性

肼在金属表面上分解机理的理论研究

键指数归一-二次指数势(Unity Bond Index-Quadratic Exponential Potential,UBI-QEP)法被用于研究肼在Fe,Ru,Pt和Cu表面上的分解机理.研究结果表明,肼在金属上优先发生N—N键断裂,金属活性顺序是Ru~Fe>Pt>Cu,但不同金属上呈现出不同的产物选择性.在Fe,Ru上产物主要为N2和H2,其通过N2Hx物种形成的可能性较低,金属活性顺序为Ru>Fe;而在Cu,Pt上最终产物为NH3,N2和H2,其中H2和N2的形成可能部分源于中间体物种N2H的转化,金属的活性顺序为Pt>Cu

肼在金属表面上分解机理的理论研究

键指数归一-二次指数势(Unity Bond Index-Quadratic Exponential Potential,UBI-QEP)法被用于研究肼在Fe,Ru,Pt和Cu表面上的分解机理.研究结果表明,肼在金属上优先发生N—N键断裂,金属活性顺序是Ru~Fe>Pt>Cu,但不同金属上呈现出不同的产物选择性.在Fe,Ru上产物主要为N2和H2,其通过N2Hx物种形成的可能性较低,金属活性顺序为Ru>Fe;而在Cu,Pt上最终产物为NH3,N2和H2,其中H2和N2的形成可能部分源于中间体物种N2H的转化,金属的活性顺序为Pt>Cu

Pathways between superoxide and peroxide species on small La-O clusters

采用密度泛函理论方法考察了lA-O团簇上超氧物种与过氧物种间转化的连接途径.单重态下,团簇上单个超氧物种可通过一系列臭氧物种转化为过氧物种,且转化能垒较高;三重态下,单个超氧物种则并无与过氧物种间连接的途径.然而,lA-O团簇上两超氧物种间的相互作用及其转化也具单重态和三重态两条途径.三重态下,超氧物种可很容易地转化为过氧物种(O2+O2O22+O2),超氧物种与过氧物种处于快速的交换状态之中;单重态下,超氧物种转化为过氧物种则需较高的活化能垒,表明在单重态下这些氧物种具有较高的稳定性.Density functional theory calculations were used to investigate the connection between superoxide and peroxide species on La-O clusters.In the singlet state,a superoxide species can transition into a peroxide species by moving through a substantial energy barrier via a series of ozonides.In the triplet state,there is no connection between the two species,although there are two paths(singlet and triplet) that allow the interaction and subsequent transformation of two superoxide molecules on a La-O cluster.The superoxide species readily transitions to a peroxide species through a triplet pathway(O2–+ O2– O22– + O2),in which the superoxide species undergoes rapid exchange with the peroxide.In the singlet path,however,the superoxide species must move through a pronounced energy barrier to change into a peroxide species,demonstrating that these oxygen species are high- ly stable in the singlet state.supportedbytheNationalBasicResearchProgramofChina(973Program;2010CB732303); theNationalNaturalScienceFoundationofChina(21033006;21373169;20373054); theProgramforChangjiangScholarsandInnovativeResearchTeamintheUniversity(IRT1036)~

能量分解法在羰基配合物成键本质研究中的应用

通讯联系人, E-mail： [email protected]借助量子化学能量分解法的思想,以对Cr(CO)6及TMq(CO)6(TMq=Hf2-,Ta-,W,Re+,Os2+,Ir3+)中金属-羰基的成键中能量贡献的分解分析为例,对金属-羰基成键中不同类型的相互作用和成键本质进行了分析和总结,并与人们传统的认识进行了比较。国家基础科学人才培养基金(J0630429

Monte Carlo法模拟CO在Fe(100)表面的升温脱附

以类桥位的模型为基础，采用ＭｏｎｔｅＣａｒｌｏ算法，结合键级守恒－Ｍｏｒｓｅ势方法（ＢＯＣ－ＭＰ），模拟了ＣＯ在Ｆｅ（１００）表面上平躺式吸附，考虑了金属与吸附质（Ｍ—Ａ）、吸附质与吸附质（Ａ—Ａ）之间的相互作用，以研究小分子在金属表面上的ＴＰＤ谱图，分析了ＣＯ的解离过程和脱附过程对ＴＰＤ谱图的影响，结果表明，理论模拟与实验相