New Method of Nanosilicon Preparation by Pulsed-laser Deposition

采用高强度激光灼蚀沉积(PLD)的方式,在流动N2做为保护气体的情况下,成功制备出Si纳米结构,并利用扫描电镜(SEM)、光致发光(PL)进行表征。结果表明,该方法制备的纳米Si尺寸在几nm到几10nm之间,同时它具有较强的发光,发光强度比同等测量条件下的多孔Si(PS)样品高10倍以上,而且方法比较简单。The photo-luminescence of Si-based material is one of the most interesting and difficult subjects in research field.Nano-silicon will be a useful way to realize silicon-based photoluminescence.A new pulsed-laser-deposition(PLD) method to produce nano silicon is reported then according to SEM and photo-luminescence(PL) it′s characters are expressed.The results show that n-Si produced by the new pulsed-laser deposition(PLD) style has a great PL intensity.For the simpleness of new PLD style,it will be of some reference value for silicon-based PL rereach.国家自然科学重点基金资助项目(60336010

A Study on the Photoluminescence Spectroscopy of Silicon Nanocrystal Formed by Pulse-laser Deposition

在激光灼蚀(PLD)系统中,采用流动的N2作为环境气体成功制备了尺寸从2纳米到几纳米之间的纳米硅,并在1.60～1.75eV之间观测到了较强的光致发光谱:结合Raman散射和光致发光谱的分析,推断强光致发光来源于纳米硅的量子效应。It has been successful to fabricate silicon nanocrystal from 2 nm to several nanometers by pulse-laser deposition using flowing N_2 as atmosphere gas.Strong photoluminescence between 1.6 eV and 1.75 eV has been observed.The origin of the photoluminescence was investigated by Raman scattering spectroscopy and photoluminescence spectroscopy.It was deduced that the strong pholuminescence stems from quantum effect.国家自然科学重点基金(批准号:60336010)资助项

丙烷选择氧化制丙烯醛VTeO/SiO_2催化剂的反应性能与结构表征

运用浸渍法制备了一系列不同组成的VTeO/SiO2催化剂,并采用XRD、TPR、Raman等技术,研究了VTeO/SiO2催化剂的结构及其对丙烷选择氧化制丙烯醛反应的催化性能.结果表明,在VOx/SiO2催化剂中添加适量Te,丙烯醛选择性和收率显著提高.VTeO/SiO2催化剂与单组分催化剂结构明显不同.由于V、Te之间的相互作用,在VTeO/SiO2催化剂表面由[TeO4]、[Te2O5]和多钒酸盐类物种形成一种高分散的无定形结构.这种结构可能由于催化活性中心的高度分散而有利于丙烷选择氧化生成丙烯醛

湿化学法制备纳米氧化镱的研究

采用通常的溶液沉淀、微乳液及均匀沉淀等溶液方法制备纳米氧化镱 .TEM观测显示 ,采用H2 O2 的溶液沉淀法和采用CTAB的均匀沉淀法 ,都可得到有较好分散、尺度约为 10nm的球形粒子 ;XRD分析表明 ,经 65 0℃焙烧后的氧化镱均为立方结构 ,采用H2 O2 的溶液沉淀法所得氧化镱的晶粒尺寸为 9 4nm ,采用CTAB的均匀沉淀法所得氧化镱的晶粒尺寸为6 9nm ;基于低温N2 吸附表征结果发现 ,微乳液法制得的Yb2 O3 的比表面积较低 ,采用H2 O2 的溶液沉淀法可以制得比表面积为 47 7m2 /g、等效粒径为 13 6nm的Yb2 O3 ,采用CTAB的均匀沉淀法所得氧化镱比表面积为 63 2m2 /g ,等效粒径为 10 3nm .表面活性剂与水合氧化镱沉淀物间的相互作用 ,可能对所得氧化镱的热稳定性有重要影响

Catalytic Performance of MoVBiTeO/SiO_2 for Selective Oxidation of Propane to Acrolein

[中文文摘]用浸渍法制备了一系列不同Mo/V比的MoVBiTeO/SiO2催化剂,并用X射线衍射、拉曼光谱、X射线光电子能谱、程序升温还原和红外光谱等方法对催化剂的结构、氧化还原性质和酸性进行了表征,考察了催化剂对丙烷选择氧化制丙烯醛反应的催化性能.结果表明,Mo与V组分之间存在较强的相互作用,调变了催化剂的结构,并形成了氧化还原循环(V5++Mo5+V4++Mo6+),促进了催化剂中电子和O物种的传递,使催化剂的低温可还原性增强,催化活性提高.Mo组分有利于形成L酸位,而V组分有利于形成B酸位.这可能是丙烯醛选择性随Mo/V比增大而逐渐提高的原因之一.当Mo/V摩尔比为6时,催化剂具有最高的丙烯醛收率(9.7%)。[英文文摘]A series of MoVBiTeO/SiO2 catalyst samples with different Mo/V ratios were prepared by the impregnation method.The catalyst structure,reducibility,and acidity were characterized by XRD,Raman,XPS,TPR,and FT-IR techniques,and the catalytic performance of the catalyst for selective oxidation of propane to acrolein was evaluated.The results indicated that the interaction between Mo and V components modified the catalyst structure,and the redox cycle of V5++Mo5+V4++Mo6+ was formed.The improvement in the reducibility of the catalyst might be responsible for the increase in propane conversion. The V and Mo components were responsible for B acid and L acid , respectively. When the Mo/ V ratio increased , the amount of B acid de2 creased , and the catalyst selectivity for acrolein increased. Among the investigated catalyst samples , the sample with a Mo/ V molar ratio of 6 exhibited the best catalytic performance.国家重点基础研究发展计划(2005CB221408); 国家自然科学基金(20433030,20021002,20423002); 福建省科技重大专项(2005HZ01-3)

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

Ni和Ce前驱体对Ni-CeO2/SiO2催化剂的甲烷部分氧化制合成气性能的影响

以不同Ni和Ce的化合物为前驱体、商品SiO2为载体，采用浸渍法制备了一系列Ni/SiO2、CeO2/SiO2和Ni-CeO2/SiO2催化剂，对CeO2在SiO2载体上的分散情况进行了表征，在此基础上进一步探究了不同前驱体制备的CeO2/SiO2对Ni的稳定情况以及Ni-CeO2/SiO2催化剂的甲烷部分氧化（methane partial oxidation, POM）制合成气的反应性能，并考察了Ni物种与CeO2之间的相互作用。研究发现，以Ce(NO3)3或Ce(NO3)3添加柠檬酸（CA）制备的CeO2/SiO2样品的H2-TPR谱图中均同时出现了表面CeO2和体相CeO2物种的还原峰，而以Ce(CH3COO)3制备的CeO2/SiO2样品上则主要含表面CeO2物种。不同前驱体制备的1%Ni/SiO2催化剂的POM反应稳定性均较差。向1%Ni/SiO2中添加CeO2后，以硝酸盐或硝酸盐添加柠檬酸制备的1%Ni-10%CeO2/SiO2催化剂的POM反应稳定性均显著提高，说明相关样品上的CeO2物种可以较好地稳定催化剂上的Ni物种，防止其在反应条件下烧结。通过H2-TPR表征可知，对于以Ce(NO3)3或Ce(NO3)3添加柠檬酸制备的1%Ni-10%CeO2/SiO2催化剂，Ni物种的还原峰温均有所提高，说明相关样品上的CeO2与Ni物种之间存在较强的相互作用。而与以Ni(CH3COO)2为前驱体制备的1%Ni/SiO2相比，以Ni(CH3COO)2和 Ce(CH3COO)3为前驱体制备的1%Ni-10%CeO2/SiO2催化剂的POM反应稳定性并未得以显著改善，其原因可能是该催化剂上的CeO2与Ni物种之间的相互作用较弱，不利于稳定镍物种。国家自然科学基金(21473144,21872111)教育部创新研究团队项目(IRT＿14R31

Highly-Dispersed NiO Nanoparticles on SBA-15 for Oxidative Dehydrogenation of Propane to Propylene

Corresponding authors. WENGWei-Zheng, Email: [email protected]; Tel: +86-592-2185192. WAN Hui-Lin, Email: [email protected]; Tel: +86-592-2186569.[中文文摘]采用浸渍法通过改变焙烧气氛制备了系列NiO/SBA-15(wNiO=20%)催化剂,并考察了催化剂的丙烷氧化脱氢(ODHP)反应性能.实验结果表明,与在静止和流动空气中焙烧的催化剂相比,在1%NO/He(VNO/VHe=1:99)气氛中焙烧的NiO/SBA-15-NO具有优异的低温丙烷氧化脱氢制丙烯性能,在350°C时,丙烷的转化率和丙烯收率分别约达29%和13%.反应温度升至450°C时,丙烯的选择性仍保持在45%左右.X射线粉末衍射(XRD)和透射电镜(TEM)测试结果表明,1%NO/He气氛可有效抑制焙烧过程中NiO纳米颗粒的团聚,使NiO物种高分散于SBA-15的孔道中.H2-程序升温还原(H2-TPR)和O2-程序升温脱附(O2-TPD)测试结果表明,随着NiO在SBA-15上分散度的提高,催化剂的抗还原性增强,ODHP活性氧物种O-的含量增加,进而使1%NO/He气氛中焙烧的NiO/SBA-15-NO在较宽的温度范围内(350-450°C)均具有良好的丙烯选择性,并显著提高了催化剂的低温活性. [英文文摘]A series of NiO/SBA-15 (wNiO=20%) catalysts were prepared by impregnating SBA-15 with an aqueous solution of nickel nitrate followed by calcining under three different atmospheres. The resulting materials were studied with regard to the oxidative dehydrogenation of propane (ODHP) to propylene.Compared to the catalysts calcined under either static or moving air, the NiO/SBA-15-NO catalyst calcined under flowing 1%NO/He (VNO/VHe=1:99) atmosphere demonstrated greater activity for this reaction at low temperature. Propylene yield of ~13% with propane conversion of ~29% was obtained at 350 °C and the propylene selectivity remained at about 45% even when the reaction temperature was raised to 450 °C.X-ray diffraction (XRD), transmission electron microscopy (TEM), H2-temperature program reduction (H2-TPR), and O2-temperature program desorption (O2-TPD) characterizations were used to investigate the intrinsic differences between these NiO/SBA-15 catalysts. It was found that NiO species in the catalyst calcined under 1%NO/He atmosphere were highly dispersed inside the mesopores of SBA-15. With the increasing of NiO dispersion on the support, the quantity of NiO species with a reduction temperature above 450 °C increased significantly. In addition, the density of O- species on the catalyst calcined under 1%NO/He was much higher than that in the case of the other two samples. These factors are responsible for the superior performance of the NiO/SBA-15-NO catalyst for the ODHP reaction over the temperature range 350 to 450 °C.国家重点基础研究发展计划(973)(2010CB732303);国家自然科学基金(21173173,21073148,21033006);教育部创新团队项目(IRT1036);福建省重大科技专项(2009HZ0002-1)资助项

丙烷选择氧化制丙烯醛MoVTeO/SiO_2催化剂结构与性能研究

考察了MoVTeO/SiO2 系列催化剂对丙烷选择氧化制丙烯醛反应的催化性能 ,结合XRD ,Raman和TPD等表征结果研究了催化剂结构、表面性质与催化性能之间的关系 .结果表明 ,以Mo为主要活性组分的催化剂 (MoV0 .2 Te0 .1/SiO2 )具有较好的催化性能 .在V ,Te组分存在下 ,Mo物种的分散度和MoO3 的可还原性能提高 .以表面钼酸盐和多钼酸盐类形态存在的高分散Mo物种有助于提高催化活性 ,而催化剂较弱的表面酸性对丙烯醛的生成有利

Rh/SiO_2催化剂上甲烷部分氧化制合成气的反应机理

采用原位Raman光谱技术,在原料气中的O2未完全耗尽的条件下,对CH4部分氧化制合成气反应的Rh/SiO2催化剂床层前部贵金属物种的化学态以及由CH4解离所生成的碳物种进行了表征.在此基础上采用脉冲反应和同位素示踪技术,比较了CH4的部分氧化及其与H2O和CO2的重整等反应对催化剂床层氧化区内CO和H2生成的相对贡献,并将实验结果与Ra-man光谱表征结果进行了关联.结果表明,在600°C下将还原后的4%Rh/SiO2催化剂切入CH4:O2:Ar=2:1:45原料气,催化剂床层前部未检测到铑氧化物的Raman谱峰,但可清晰检测到源于CH4解离的碳物种;在700°C和接触时间小于1ms的条件下,催化剂床层的氧化区内已有大量CO和H2生成,在相同的实验条件下,CH4与H2O或CO2重整反应对氧化区内合成气生成的贡献则很小;以CH4:16O2:H218O:He=2:1:2:95为原料气的同位素示踪实验结果表明,在原料气中16O2未完全耗尽的情况下,反应产物中C16O的含量占CO生成总量的92.3%,表明CO主要来自CH4的部分氧化反应.上述结果均表明,在O2存在下Rh/SiO2催化剂上CO和H2可以通过CH4直接解离和部分氧化机理生成