Adsorption of Gases on Complex Solid Surfaces

During the last thirty years the research field of surface science with its various disciplines has progressively played a more and more important role in the field of catalysis. The main focus of attention for a long time was research on metal surfaces, on which, in time, the whole spectrum of developed surface analytical methods was applied. This led to a better understanding of the mechanisms of catalytic reaction, such as the synthesis of ammonia and the oxidation of CO, especially through the work of Gerhard Ertl.^{[1, 2]} In contrast to clean metal surfaces, surfaces of real catalysts are complex entities, the structures of which can have a strong influence on the processes occurring on the surface. Thus, it seems logical to employ the typical structural characteristics and the morphology of the catalytic surface as guidelines in the investigation of complex model systems. In this review the preparation, and structural and electronic characterization of such model systems will be dicussed. Clean surfaces of catalytically active oxides, as well as model systems for dispered transition metal/support catalysts will be characterized in terms of their morphology and electronic structure as well as their adsorption and reaction capabilities.     

Prediction of Nucleophilicity and Electrophilicity Based on a Machine-Learning Approach

Nucleophilicity and electrophilicity dictate the reactivity of polar organic reactions. In the past decades, Mayr et al. established a quantitative scale for nucleophilicity (N) and electrophilicity (E), which proved to be a useful tool for the rationalization of chemical reactivity. In this study, a holistic prediction model was developed through a machine-learning approach. rSPOC, an ensemble molecular representation with structural, physicochemical and solvent features, was developed for this purpose. With 1115 nucleophiles, 285 electrophiles, and 22 solvents, the dataset is currently the largest one for reactivity prediction. The rSPOC model trained with the Extra Trees algorithm showed high accuracy in predicting Mayr's N and E parameters with R² of 0.92 and 0.93, MAE of 1.45 and 1.45, respectively. Furthermore, the practical applications of the model, for instance, nucleophilicity prediction of NADH, NADPH and a series of enamines showed potential in predicting molecules with unknown reactivity within seconds. An online prediction platform (http://isyn.luoszgroup.com/) was constructed based on the current model, which is available free to the scientific community.     

氧原子和羟基在Ni低指数表面的吸附动力学研究

应用5-参数Morse势方法模拟了O－Ni表面相互作用势,考察了氧原子在镍三个低指数表面的吸附特性.同时构造了羟基与Ni（100）、Ni（110）和Ni（111）表面相互作用的推广LEPS势,获得了羟基在表面的吸附位、吸附几何、结合能及本征振动等数据.理论结果表明,羟基垂直吸附于镍表面的高对称位是稳定的,垂直吸附于Ni（100）表面4-重洞位的吸附能为96.98 kJ•mol－1,垂直吸附于Ni（111）表面3-重洞位的吸附能为96.00 kJ•mol－1,在Ni（110）表面存在两种吸附态：垂直吸附于长桥位的吸附能为99.38 kJ•mol－1,倾斜14°吸附于赝势三重位吸附能为96.98 kJ•mol－1.理论结果与实验结果符合得较好.     

PVP-Supported Palladium-Cadmium Bimetallic Catalyst for the Hydrogen Transfer Dechlorination of Aryl Chlorides

SupportedbimetalIiccatalysts,duet0theirhighselectivityandcatalyticactivity,havebeenxvidelyappliedtothehydrogenationofnitro-compounds'andesters',thecarb0n}lIati0n0fallylhalides'andthecatalytichydrodehalogenati0nofaromatichalides;'.LiaoandothersutilizedPVP[PVP=poly-(N-vinyl-2-pyrrolidone)]-supp0rtpaIladium-rutheniUm'andpalladium-c0balt'bimetalliccatalysts,inthepresence0fdihydrogen,tocatalyzethehydr0dechl0rinati0n0farylchl0rides.Alth0ughthesereacti0nshadhighcatalyticactivity,the0perati0nwasra…     

氢原子在钯低指数表面上的吸附和扩散

采用氢－钯相互作用的五参数Ｍｏｒｓｅ势，用对势方法研究了氢原子在Ｐｄ（１００）、Ｐｄ（１１１）和Ｐｄ（１１０）低指数平坦表面上的吸附和扩散，得到氢原子在三个表面上的吸附位、吸附几何、结合能和本征振动等数据，计算结果和实验结果符合得很好。在此基础上，系统地研究了三个系统的吸附扩散势能面结构。     

机器学习筛选用于气体吸附分离和存储的金属有机骨架材料

金属有机框架（Metal-organic framework ,MOF）因其高孔隙率、高比表面积和结构可调性,在气体吸附分离领域广泛应用。随着MOF数量激增,传统分子模拟和实验方法验证MOF性能成本高且速度慢,因此目前MOF筛选工作已转向高通量计算辅助的机器学习（Machine-learning,ML）。机器学习作为一种高效的大数据处理方法,能够在高通量筛选（High-Throughput Computational Screening,HTCS）的基础上对数据进行拟合,从而快速而准确地筛选出气体吸附分离材料,并深入挖掘其结构与性能之间的关系。本文回顾了近年机器学习应用于MOF筛选的研究。本文重点讨论了一些运用机器学习从大量结构中筛选出可用于CH4、H2和CO2等气体吸附分离与储存的MOF材料的工作。同时,我们梳理了当前MOF材料筛选工作中的研究思路和进展,并指出了机器学习在筛选MOF材料工作中面临的一些瓶颈和挑战。最后,对该领域的未来发展前景进行了展望。     

An efficient Approach to Modify the Catalyst Activity for the Hydrogenation of Nitrobenzene

Transition metal complexes have been used extensively for the hydrogenation in homogeneous system probably due to their high catalytic selectivities under mild operating conditions. In order to improve the homogeneous catalyst system, some studies on the homogeneous or soluble polymer-supported bimetallic catalysts have been recently carried out and enhanced activity, better selectivity were observed in selective hydrogenation, hydrodehalogenation, carbonylation, hydroformylation and regioselec…     

手性催化剂负载的一种新方法: 自负载策略

较系统地介绍了手性催化剂负载的一种新方法(即“自负载”策略)及其在非均相不对称催化反应中应用的最新进展. 与传统的负载模式不同, “自负载”策略中利用含双或多官能团的配体与金属通过自组装形成的有机-无机聚合物做为催化剂, 因此不需使用任何载体. “自负载”手性催化剂在若干非均相不对称催化反应中显示了优秀的催化活性和对映选择性并且能够简单回收再利用, 为手性催化剂的负载化提供了一个新的策略.     

负载Ru催化剂的CO吸附态的研究

本文运用原位FT-IR光谱系统研究了各种活化处理因素对负载Ru催化剂的CO吸附态的影响.发现2135±15(HF)和2075±5(MF)cm~(-1)IR谱峰产生于金属与载体接触的周边部位,反映了以多重态吸附的CO对称和反对称振动.金属载体间的相互作用的增强,HF和MF强度大幅度衰减.经纯O_2处理的催化剂,HF和MF峰位置没有发生变化,而峰强度随吸附时间的相对增长速率有很大的差异.对HF和MF作了归属,提出了6配位18电子紧壳层稳定结构的表面锚合的羟基氧桥或卤桥的多聚羰基化合物种CO吸附模式.     

CO在无序二元合金表面上化学吸附研究

在紧束缚近似下，用相关势近似（CPA）和Einstein-Schrieffer（ES）单电子化学吸附理论讨论了CO在无序二元合金NixCu1-x,PtxNi1-x和PtxCu1-x表面上的化学吸附特性,结果表明：CO在NixCu1-x和PtxCu1-x表面上化学吸附稳定性随Ni和Pt含量的增加而增强；CO在PtxNi1-x表面上化学吸附时，当Pt与Ni的含量比例（摩尔比）为2：8时，吸附最稳定，在Pt与Ni的含量比例（摩尔比）为7:3时最不稳定     

含茂金属的双组分或多组分催化体系的研究与应用

评述了含茂金属的双组分或多组分催化体系的基础研究与应用。大多数含茂金属的双组分或多组分催化体系用于制备宽分子量分布聚烯烃,尤其是宽分布聚乙烯,少数用于制备支化或嵌段聚合物。双组分或多组分催化体系已经成为分子剪裁与材料设计的重要手段之一。     

High-Loading Pt Single-Atom Catalyst on CeO2-Modified Diatomite Support

Single-atom catalysis has become a new branch in heterogeneous catalysis. Although the naturally produced SiO₂-based materials are abundant and stable, fabrication of single-atom catalysts on such supports with high loading remains as a formidable challenge due to the lack of bonding sites to anchor the isolated metal species. Herein, modifying the diatomite, a kind of pure SiO₂ mineral, with CeO₂ nanoparticles is demonstrated to increase the defect sites on the support. The enhanced metal-support interaction maintains the atomic dispersion of Pt species with above 1 wt.% loading, exhibiting good performance in the selective hydrogenation of phenylacetylene to styrene.     

Ni-Co双金属催化剂上沼气重整制氢机理

用传统湿式浸渍法制备了La₂O₃掺杂的商业γ-Al₂O₃负载的沼气重整催化剂Ni-Co/La₂O₃-γ-Al₂O₃, 并用程序升温加氢(TPH)、程序升温氧化(TPO)、程序升温表面反应(TPSR)、程序升温脱附(TPD)及脉冲实验对催化剂进行了表征. 结果表明, 沼气重整过程中Ni-Co/La₂O₃-γ-Al₂O₃催化剂上的表面碳物种主要来源于CH₄的裂解, CO₂的贡献很小. CH₄裂解能够产生三种活性不同的碳物种, 即C_α、C_β与C_γ. 随着反应的进行, C_α物种减小而C_β与C_γ物种增加, 且C_γ物种能够转变为惰性的石墨碳. 重整反应过程中CH₄与CO₂的活化能相互促进. 催化剂表面的O物种与C反应生成CO或与CH_x反应生成CH_xO再分解为CO与吸附态的H物种, 可能是Ni-Co/La₂O₃-γ-Al₂O₃催化剂上沼气重整的速率控制步骤.     

Fast Adsorption of Soft Hydrogel Microspheres on Solid Surfaces in Aqueous Solution

The real‐time adsorption behavior of polymeric colloidal microspheres onto solid surfaces in aqueous solution was visualized for the first time using high‐speed atomic force microscopy (HS‐AFM) to reveal how the softness of the microspheres affects their dynamic adsorption. Studies that focus on the deformability of microspheres upon dynamic adsorption have not yet been reported, most likely on account of a lack of techniques that appropriately depict the dynamic adsorption and deformation behavior of individual microspheres at the nanoscale in real time. In this study, the deformability of microspheres plays a crucial role on the adsorption kinetics, that is, soft hydrogel microspheres adsorb faster than harder elastomeric or rigid microspheres. These results should provide insight towards development of new colloidal nanomaterials that exhibit effective adsorption on specific sites in aqueous solution.     

还原态钼铝催化剂上NO的吸附研究

通过对红外光谱及同位素交换反应后的分析 ,证明吸附在还原态钼铝催化剂上的NO是以双亚硝酰基形式存在的     

固载液相铂催化剂催化3-氯丙烯硅氢加成反应

固载液相铂催化剂催化3-氯丙烯硅氢加成反应;固载液相铂催化剂;硅氢加成;催化;氯丙烯     

PFOS在锐钛型TiO2表面吸附行为的理论研究

采用密度泛函理论(DFT)B3LYP方法对全氟辛烷磺酸(PFOS)在锐钛型TiO2表面的化学吸附和物理吸附行为进行了研究,其中化学吸附包含双齿双核(BB)和单齿单核(MM)在内的4种可能的吸附构型.吸附能(Eads)及反应吉布斯自由能(ΔGads)的计算结果表明,PFOS分子易于与TiO2表面发生氢键作用吸附;化学吸附表现为PFOS分子与TiO2表面的水分子(H2O)和羟基(—OH)反应,且与取代—OH相比,H2O取代相对更容易发生,其中,MM1构型(取代一个表面水分子)为化学吸附中的优势构型.PFOS在锐钛矿表面吸附的热力学稳定性和反应自发性顺序如下:H-Bonded(氢键吸附)>MM1(取代一个表面水分子)>BB1(取代两个表面水分子)>MM2(取代一个表面羟基)>BB2(取代一个表面水分子和一个表面羟基).成键结构分析表明,TiO2表面H2O/—OH官能团与PFOS上的磺酸基之间形成了中等强度的氢键;在化学吸附过程中,电荷从PFOS分子向TiO2表面发生转移,生成Ti—O—S化学键,电荷转移主要来自PFOS分子的O和F原子.     

多相双功能催化剂上的不对称直接Aldol反应

通过将手性胺和酸基团同时引入到二氧化硅表面制备得到了一种多相双功能催化剂.该催化剂在不对称直接Aldol反应中表现出中等的催化活性和对映选择性(ee值最高可达60%以上).催化剂中手性胺和酸基团的协同作用对反应的活性和手性诱导至关重要.