Deuterium Inverse Isotopic Effect in Ammonia Synthesis over Ru-Based and Fe-Based Catalysts

联系人: 林敬东.Tel:(0592)2183045;Fax:(0592)2183043; E-mail: [email protected] 廖代伟. Tel:(0592)2183045;Fax:(0592)2183043; E-mail: [email protected][中文文摘]氘反同位素效应是合理阐明过渡金属催化剂上氨合成催化反应机理的重要实验依据之一.在N2/H2(或D2)体积比1/3,0.2MPa,633～733K和GHSV=24000或12000h-1的条件下,检测到了Ru基(纯Ru,Ru/γ-Al2O3,K-Ru/γ-Al2O3,Ru/MgO,K-Ru/MgO和Ba-Ru/MgO)和Fe基(纯Fe和A110-3)催化剂上强的氘反同位素效应(rD/rH≈2),其数值随催化剂和反应温度的变化而变化.这可能是动力学同位素效应与热力学同位素效应二者相互强竞争的结果.[英文文摘]The deuterium inverse isotopic effect (DIIE) is important for the clarification of the ammonia synthesis mechanism over transition metal catalysts. We investigated the DIIE over Ru-based and Fe-based catalysts including pure Fe,multi-promoted fused Fe,pure Ru,Ru/γ-Al2O3,K-Ru/γ-Al2O3,Ru/MgO,K-Ru/MgO,and Ba-Ru/MgO under the reaction conditions of N2/H2 (or D2) volume ratio = 1/3,0.2 MPa,633–733 K,and GHSV = 24 000 and 12 000 h?1. A strong DIIE (rD/rH of about 2) was observed over the above catalysts. The trend of the DIIE with catalysts and temperature indicated a strong competition between the dynamic and thermodynamic factors.国家自然科学基金(20673089);国家重点基础研究发展计划(973计划,2009CB939804

Preparation and Characterization of Sinter-Resistant RhSm2O3/SiO2 Catalyst and Its Performance for Partial Oxidation of Methane to Syngas

以乙酰丙酮铑(Rh(acac)_3)和乙酰丙酮钐(Sm(acac)_3)为前驱体,用浸渍法制备了Rh/SiO_2和Rh-Sm_2O_3/SiO_; 2催化剂。采用原位红外光谱、热重分析、低温N_2吸附、X射线粉末衍射、高分辨透射电子显微镜、H_2-程序升温还原和X射线光电子能谱等实验技术对催; 化剂的制备过程,比表面积和物相以及Rh与Sm_2O_3间的相互作用进行了表征,并以甲烷部分氧化制合成气为目标反应对催化剂的稳定性进行了考察。研究; 表明:以Rh(acac)_3和Sm(acac)_3为前驱体采用简单的浸渍法即可制备出Rh平均粒径为2.3; nm且具有良好抗烧结性能的Rh-Sm_2O_3/SiO_2催化剂。在浸渍过程中乙酰丙酮化合物通过与SiO_2表面羟基形成氢键而负载于载体表面。S; m(acac)_3在SiO_2表面的单层负载量(质量分数)约为31%,对应于Sm_2O_3的质量分数约为15%,只要Sm(acac)_3的质量分; 数低于这一阈值,均可保证分解后生成的Sm_2O_3以高分散形式负载于SiO_2上,且不会因高温(800; °C)焙烧而团聚。高分散于SiO_2表面的Sm_2O_3与Rh之间存在强的相互作用,可显著提高Rh的分散度,防止其在高温反应条件下烧结,进而使低; Rh负载量的催化剂表现出良好的甲烷部分氧化制合成气反应活性和稳定性。Rh/SiO2 and Rh-Sm2O3/SiO2 catalysts were synthesized by the conventional impregnation method using rhodium acetylacetonate (Rh(acac)(3)) and samarium acetylacetonate (Sm(acac)(3)) as precursors. The preparation and catalytic properties, as well as the interaction between Rh and Sm2O3, were characterized in detail by in situ infrared spectroscopy (IR), thermogravimetric analysis (TG), N-2 physisorption (Brunauer-Emmett-Teller (BET) method), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), temperature-programmed reduction (H-2-TPR) and X-ray photoelectron spectroscopy (XPS). The performance of the catalysts for the partial oxidation of methane (POM) to syngas was also investigated. The results showed that a sinter-resistant Rh-Sm2O3/SiO2 catalyst with an average Rh particle size of similar to 2.3 nm could be synthesized using the conventional impregnation method with Rh(acac)(3) and Sm(acac)(3) as precursors. The surface silanol groups of SiO2 acted as the centers to interact with M(acac)(3) (M=Rh, Sm) molecules when SiO2 was impregnated in the M(acac)(3) solution, leading to the formation of a hydrogen-bonded M(acac)(3) layer on the SiO2 surface. In this experiment, the monolayer coverage of Sm(acac)(3) on the SiO2 surface was equal to a Sm(acac)(3) loading (mass fraction) of approximately 31%, which in turn corresponded to a Sm2O3 loading of approximately 15%. When a Sm(acac)(3)/SiO2 sample with Sm(acac)(3) loading below 31% was heated in air to approximately 360?, the monolayer Sm(acac)(3) species decomposed into highly dispersed Sm2O3 species on the SiO2 surface, which displayed superior stability against sintering at high temperature. No aggregation of the Sm2O3 species was observed even when the sample was heated to 800 degrees C in air. The strong interaction between the highly dispersed Sm2O3 and Rh plays a key role in increasing the dispersion of Rh species in the catalyst and preventing the Rh species from sintering under high temperature conditions. This factor should also be responsible for the superior activity and stability of the Rh-Sm2O3/SiO2 catalyst with extremely low Rh loading for the catalytic partial oxidation of methane to syngas.国家重点基础研究发展规划项目（2013CB933102）,国家自然科学基金（21473144,21373168）,国家基础科学人才培养基金项目（J1310024）及教育部创新研究团队项目（IRT_14R31）资

氧化石墨烯改性高温环氧树脂基碳纤维复合材料的热性能与力学性能

采用湿法预浸技术和模压工艺,制备了氧化石墨烯(GO)改性碳纤维/环氧树脂(CF/E54-DDS)混杂复合材料,利用差示扫描量热分析(DSC)、动态热机械分析(DMTA)、无损C扫描等开展了GO对复合材料的热固化性能、凝胶工艺性、动态热机械性能以及抗冲击损伤性能等的影响研究。结果表明,GO结构中的羟基、羧基会促进改性树脂体系的固化反应,GO/E54-DDS的固化反应比E54-DDS的提前,反应变得和缓,且会加速固化反应的进行;在GO含量小于0.5%时,GO的活性基团可增加改性体系的交联密度而提高复合材料的玻璃化转变温度,但GO含量大于0.8%时,会因DDS在固化网络结构中的占比下降较大,反而降低复合材料的玻璃化转变温度;GO/CF/E54-DDS预浸料比CF/E54-DDS表现出更好的浸润效果;CF/E54-DDS复合材料破坏后碳纤维表面光洁,破坏主要发生在碳纤维与树脂基体的界面,而GO/CF/E54-DDS复合材料破坏后,碳纤维表面紧密粘附着GO/E54-DDS固化物,破坏主要发生在碳纤维织物层间的GO/E54-DDS区域;GO的存在提高了GO/CF/E54-DDS复合材料抵抗横向裂纹和纵向裂纹扩展的能力,复合材料的损伤投影面积和凹坑深度减小,提高了冲击后压缩强度。航空科学基金(2016ZF68011);;福建省科技创新平台建设计划(2014H2006);;福建省自然科学基金(2015J01222);;厦门大学石墨烯工业技术研究院资助项目(2014I2005

Mechanism and isotope effect of ammonia synthesis over Fe and Ru catalysts

Chemistry for Catalyst Synthesis Division of Catalysis Science and Technology (probationary) The 237th ACS National Meeting, Salt Lake City, UT, March 22-26, 200

Direct conversion of methane to formaldehyde and CO on B2O3 catalysts

甲烷作为天然气的主要成分，是非常重要的碳基资源。不过，甲烷分子的化学惰性使得其转化通常需要在高温条件下进行，反应选择性难于控制。如何实现甲烷的高选择性定向转化一直是化学研究中的重要挑战，甚至被誉为化学领域的“圣杯”。化学化工学院王帅教授与华盛顿州立大学王勇教授合作在甲烷选择氧化反应非金属硼基催化剂的研究中取得重要进展，本研究中发现负载型氧化硼催化剂在甲烷直接氧化反应中表现出优异的抗深度氧化能力。本研究工作是在王帅教授和王勇教授的共同指导下完成。2015级博士生田金树（已毕业）、硕士生谈江乔（已毕业）以及醇醚酯清洁生产国家工程实验室张朝霞工程师为共同第一作者，林敬东副教授和万绍隆副教授等参与了部分研究和讨论。【Abstract】Direct oxidation of methane to value-added C1 chemicals (e.g. HCHO and CO) provides a promising way to utilize natural gas sources under relatively mild conditions. Such conversions remain, however, a key selectivity challenge, resulting from the facile formation of undesired fully-oxidized CO2. Here we show that B2O3-based catalysts are selective in the direct conversion of methane to HCHO and CO (~94% selectivity with a HCHO/CO ratio of ~1 at 6% conversion) and highly stable (over 100 hour time-on-stream operation) conducted in a fixed-bed reactor (550 °C, 100 kPa, space velocity 4650 mL gcat−1 h−1 ). Combined catalyst characterization, kinetic studies, and isotopic labeling experiments unveil that molecular O2 bonded to tri-coordinated BO3 centers on B2O3 surfaces acts as a judicious oxidant for methane activation with mitigated CO2 formation, even at high O2/CH4 ratios of the feed. These findings shed light on the great potential of designing innovative catalytic processes for the direct conversion of alkanes to fuels/chemicals.This work was supported by the National Natural Science Foundation of China (No. 21922201, 21872113, 91945301, 21673189, and 91545114) and the Fundamental Research Funds for the Central Universities (No. 20720190036 and 20720160032).研究工作得到了国家自然科学基金（21922201、21872113、91945301、21673189、91545114）和中央高校基本科研业务费专项资金（20720190036、20720160032）的资助与支持

增强ZnO基发光二极管紫光电致发光性能的方法

 本发明公开了一种增强ZnO基发光二极管紫光电致发光性能的方法,该方法是在ZnO/AlN界面插入一层Ag纳米颗粒,通过Ag局域态表面等离激元与器件的电致发光相互耦合,提高ZnO基发光二极管紫光电致发光性能。实验发现Ag纳米颗粒的局域态表面等离激元共振峰与ZnO近带边发光峰的位置相近,满足共振耦合条件,且粗糙的Ag纳米颗粒的表面有利于等离激元有效耦合成光且能够明显提高光的抽取效率。利用本发明,显著提高了ZnO基发光二极管紫光电致发光性能

增强n-ZnO/AlN/p-GaN发光二极管的电致发光性能的方法

 本发明公开了一种增强n-ZnO/AlN/p-GaN发光二极管的电致发光性能的方法,该方法是在n-ZnO/AlN/p-GaN发光二极管的n-ZnO薄膜中插入一层Ag纳米颗粒,利用Ag局域态表面等离激元与ZnO近带边发光强的相互耦合作用,来提高n-ZnO/AlN/p-GaN异质结发光二极管电致发光性能。实验发现Ag纳米颗粒的局域态表面等离激元共振峰与ZnO近带边发光峰的位置相近,满足共振耦合条件,且粗糙的Ag纳米颗粒的表面有利于等离激元有效耦合成光且能够明显提高光的抽取效率。利用本发明,显著提高了n-ZnO/AlN/p-GaN异质结发光二极管电致发光性能

Preparation of Monodisperse Nano-silica Microspheres

以正硅酸四乙酯(TEOS)为原料采用STObEr法制备了单分散、粒径分布均匀、平均直径范围在250~800nM的纳米二氧化硅微球.通过SEM和Xrd表征手段,探讨了水、TEOS和氨水用量对SIO2形貌和粒径的影响.结果表明,添加适量的水会得到粒径较大、均匀且分散性好的SIO2微球;随氨水和TEOS用量增多,SIO2粒径增加;若氨水用量太少,则得到粒径虽小但圆度差、表面不光滑的SIO2.Monodisperse nano-silica microspheres were prepared by conventional Stober method.Silica particles with sizes between 100 to 800 nm were obtained by alkaline hydrolysis of tetraethyl orthosilicate(TEOS) in ethanol solution.The morphology and particle size of nano-silica were investigated using SEM and XRD.The results showed that monodisperse silica particles could be obtained using proper amount of water.The results also showed that the silica particle sizes decreased with increasing amount of ammonia and TEOS,while silica particles obtained using low concentraton of ammonia appeared rough surface.国家重点基础研究发展规划(973)项目(2011CBA00508