Pt2+/Pt0掺杂g-C3N4光催化降解环丙沙星和偶氮染料

以三聚氰胺和氯铂酸(H2PtCl6·6H2O)为原材料,采用简单一步煅烧法制备了不同含量的Pt^2+/Pt^0掺杂石墨相氮化碳(Pt^2+/Pt^0-CN)。运用扫描电镜、透射电子显微镜、X射线光电子能谱、X射线粉末衍射、N2物理吸附-脱附、紫外-可见漫反射光谱和光电流测试等技术对制备的样品的形貌、化学组成、晶体结构、比表面积和光电性能等物理化学性质进行了表征。由XPS可知Pt粒子以二价Pt和零价Pt掺杂在催化剂的表面和内部,其中Pt^0与Pt^2+的比约为1∶7.26。与g-C3N4相比,Pt^2+/Pt^0-CN表现出高效的光催化降解活性。当Pt^2+/Pt^0理论负载质量分数为0.02%时,对环丙沙星、罗丹明B、酸性橙Ⅱ、甲基橙和亚甲基蓝的降解效率分别提升了43%、64%、39%、42%和52%。Pt^2+/Pt0掺杂使催化剂的比表面积大幅度增加,同时增强光催化剂对光的吸收能力,并抑制光生电子(e^-)和空穴(h^+)的复合。     

Mesoporous α-Fe2O3 nanospheres: structural evolution and investigation of magnetic properties

A solvothermal route is adopted to produce mesoporous α-Fe(2)O(3) nanospheres by using polyethylene glycol as soft template and n-butanol/H(2)O as mixed solvent. The mesoporous α-Fe(2)O(3) nanospheres are subjected to calcination at different temperatures, and the specific surface area, pore size, and magnetic properties of the as-prepared nanospheres are investigated. The studies reveal that the pore sizes of the mesoporous α-Fe(2)O(3) nanospheres increase with higher calcination temperature, and high-temperature calcination brings about tightness of the pore wall. Magnetic studies show that aggregation of the small particles raises the Morin transition temperature.     

Preparation of LaFe0.95Pd0.05O3 perovskites and their catalytic performances in methane combustion

The physic-chemical properties of LaFe0.95Pd0.05O3 perovskites were strongly dependent on the temperature of calcination. Most of the organic substances and inorganic impurities were readily removed at 723 K but single-phase and well crystallized perovskite structure was formed at 873 K. With further raising the calcination temperature, the crystallite size of LaFe0.95Pd0.05O3 increased considerably. The LaFe0.95Pd0.05O3 sample that calcined at 1073 K showed only comparable activity as the reference LaFeO3 catalyst, in particular below 923 K, but pre-treatment with the reaction gas at 1223 K resulted in significantly enhanced activity due to the generation of active PdO species on the surface. The hysteresis feature upon heating-cooling cycle further confirmed the strong interaction between Pd and LaFeO3 in the perovskite structure.     

催化剂焙烧温度对热解火焰法合成碳纳米管的影响

为了探讨在制备Fe/Mo/Al2O3载体载入式催化剂过程中的焙烧温度对实验产物的影响,在热解火焰法中,以CO为碳源,设计了6组实验工况,对不同焙烧温度的合成产物碳纳米管进行对比分析,实验产物的形貌与特征用扫描电镜和拉曼光谱表征.分析表明,在本组实验条件下,催化剂焙烧温度为800～1000℃时,可以使催化剂颗粒尺寸更小,分散性更好,催化活性更高,实验合成的碳纳米管以多壁碳纳米管为主,产量较多,质量较佳,焙烧温度为900 ℃附近时,合成了高质量的单壁碳纳米管.     

硼酸镁纳米晶须的水热-熔盐焙烧合成研究

以MgCl2·6H2O、H3BO3和NaOH为原料,采用定-转子反应器合成MgBO2 (OH)前驱体,水热合成MgBO2 (OH)纳米棒,进而熔盐焙烧合成了直径为50 ～105 nm、长度为6～13μm(平均长径比为120)、高度分散的纯单斜相单晶Mg2B2O5纳米晶须.采用XRD、SEM、EDX、TEM及SAED等手段进行表征.研究发现,MgBO2( OH)纳米棒的最佳合成条件是水热温度为210℃、水热时间为8h,该条件下可获得分散良好、形貌规则,尺寸分布范围窄的MgBO2 (OH)纳米棒.     

预处理条件对一步法合成吲哚用Ag/SiO2催化剂活性的影响

 以简单浸渍法制备的Ag/SiO2催化剂对苯胺和乙二醇一步法合成吲哚具有很高的催化活性. 研究了预处理条件对催化剂活性的影响. 结果表明,采用程序升温法将催化剂前体在500 ℃焙烧4 h,并在低于150 ℃时用H2-N2混合气(H2含量低于50%)原位还原得到的Ag/SiO2催化剂活性较高; TEM和XRD结果表明,预处理后催化剂表面银晶粒较小,结晶度较低.     

Thermal Preparation and Application of a Novel Silicon Fertilizer Using Talc and Calcium Carbonate as Starting Materials

The deficiency of available silicon (Si) incurred by year-round agricultural and horticultural practices highlights the significance of Si fertilization for soil replenishment. This study focuses on a novel and economical route for the synthesis of Si fertilizer via the calcination method using talc and calcium carbonate (CaCO₃) as starting materials. The molar ratio of talc to CaCO₃ of 1:2.0, calcination temperature of 1150 °C and calcination time of 120 min were identified as the optimal conditions to maximize the available Si content of the prepared Si fertilizer. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) characterizations elucidate the principles of the calcination temperature-dependent microstructure evolution of Si fertilizers, and the akermanite Ca₂Mg(Si₂O₇) and merwinite Ca₃Mg(SiO₄)₂ were identified as the primary silicates products. The results of release and solubility experiments suggest the content of available metallic element and slow-release property of the Si fertilizer obtained at the optimum preparation condition (Si-OPC). The surface morphology and properties of Si-OPC were illuminated by the results of scanning electron microscope (SEM), surface area and nitrogen adsorption analysis. The acceleration action of CaCO₃ in the decomposition process of talc was demonstrated by the thermogravimetry-differential scanning calorimetry (TG-DSC) test. The pot experiment corroborates that 5 g kg⁻¹ soil Si-OPC application sufficed to facilitate the pakchoi growth by providing nutrient elements. This evidence indicates the prepared Si fertilizer as a promising candidate for Si-deficient soil replenishment.     

焙烧温度对费托合成铁基催化剂还原动力学的影响

采用沉淀法和喷雾干燥技术制备了一个典型的费托合成铁基催化剂(100Fe/3K/6SiO_2,质量比)所得样品在不同温度下焙烧5 h.分别利用N_2吸附和穆斯保尔谱表征了催化剂的织构和物相性质,同时利用热重分析仪记录了催化剂在H2气氛中的还原过程,并利用气固反应模型对还原曲线进行了动力学模拟.结果表明,300~600℃焙烧后催化剂的还原过程可用相同的模型拟合,其中由α-Fe_2O_3还原为Fe_3O_4的过程可用一维晶相形成与生长模型或三维相界面反应模型描述,Fe_3O_4还原为α-Fe的过程受二维晶相形成与生长模型控制.而对于700℃焙烧后的催化剂,其还原过程可能受晶相形成与生长模型和收缩核模型共同影响.随着焙烧温度的提高,催化剂的还原能力减弱,还原过程活化能升高.这可能是由于焙烧温度的提高导致晶粒尺寸增大和晶格缺陷减少所致.     

Y2O3∶Yb3+,Tm3+纳米粉体的制备及发光性能研究

以Y2O3为基质材料,Yb3+为敏化剂,Tm3+为激活剂,采用化学共沉淀法制备Y2O3∶Yb3+,Tm3+纳米粉体,通过差热、红外光谱、XRD、荧光、上转换发光和场发射电子显微镜等方法对样品进行表征.结果表明:Tm3+和Yb3+完全固溶到Y2O3立方晶格中,且粉体大小均匀,尺寸约50 nm;Yb3+浓度为4;(摩尔分数)、煅烧温度900 ℃时,荧光和上转换发光强度最强;Tm3+浓度为0.4;时绿光(5F4/5S2→5I8)和红光(2F5/2→2F7/2)荧光强度最强,浓度0.5;时蓝光(1G4→3H6)和红光(1G4→3F4)的上转换发射强度最大.     

硫酸铜晶体制备实验的绿色化改进

对以铜粉为原料、硝酸为氧化剂的硫酸铜晶体制备实验进行了绿色化改进。结果发现,铜粉的研磨及灼烧时间、介质的酸度及氧化剂对产品质量都有影响。当铜粉的研磨时间为20 min、灼烧时间35 min及用3 mol/L的H2SO4作为介质、H2O2作为氧化剂时,产率可达67.92%,产品的质量和产率比传统的制备方法有明显提高,符合绿色化实验的要求。