固体超强酸SO_4~(2-)/SnO_2-SiO_2催化制备生物柴油的研究

以固体超强酸SO_4~(2-)/SnO_2-SiO_2为催化剂催化大豆油和甲醇的酯交换反应制备生物柴油,考察了催化剂的制备条件和反应的最佳条件.结果表明,当催化剂的Sn/Si摩尔比达1/3以上.浸渍硫酸溶液的浓度为1.0～1.5 mol/L,450℃焙烧5 h,该催化剂对酯交换反应有很高的催化活性.在醇油摩尔比为13:1、每摩尔油使用1.0 g催化剂、120℃反应3 h,脂肪酸甲酯的收率达90%以上.催化剂具有L酸中心和B酸中心,具有超强酸性.反应体系的水抑制催化剂的活性,但催化剂的活性不受体系中游离脂肪酸的影响,这意味着催化剂能高效催化那些未精炼原油和那些不可食用的油料,使酯化和酯交换一步完成.     

固体超强酸Ni/SO_4~(2-)-SnO_2催化α-蒎烯水合反应的研究

引入镍离子制备出新型固体超强酸Ni/SO42--SnO2,以该固体酸催化α-蒎烯水合反应制备α-松油醇,考察影响水合反应的因素,得到水合反应最适宜的条件为:n(α-蒎烯)∶n(一氯乙酸)∶n(H2O)=1∶1∶2,反应温度70°C,反应时间10h,催化剂用量为α-蒎烯质量的6%。在该反应条件下,α-蒎烯转化率为100%,α-松油醇选择性为73.3%;与未添加Ni的固体超强酸SO24-/SnO2相比表明,Ni的引入能明显提高催化剂在水合反应中的活性和选择性。     

Structure and electrical properties of Nd2O3-doped 0.82Bi0.5Na0.5TiO3–0.18Bi0.5K0.5TiO3 ceramics

Nd₂O₃ doped 0.82Bi_0.5Na_0.5TiO₃–0.18Bi_0.5K_0.5TiO₃ (abbreviated to BNKT) binary lead-free piezoelectric ceramics were synthesized by the conventional mixed-oxide method. The results show that the BNKT ceramics with 0–0.15 wt.% Nd₂O₃ doping possesses a single perovskite phase with rhombohedral structure. The grain size of BNKT decreased with the addition of Nd₂O₃ dopant. The temperature dependence of the dielectric constant ?_r revealed that there were two-phase transitions from ferroelectric to anti-ferroelectric and anti-ferroelectric to paraelectric. A diffuse character was proved by linear fitting of the modified Curie–Weiss law. At room temperature, the specimens containing 0.0125 wt.% Nd₂O₃ with homogeneous microstructure presented excellent electrical properties: the piezoelectric constant d₃₃ = 134 pC/N, the electromechanical coupling factor K_p = 0.27, and the dielectric constant ?_r = 925 (1 kHz).     

制备方法对Ce_(0.67)Zr_(0.33)O_2固溶体性能的影响

用氧化共沉淀法、均匀共沉淀法和柠檬酸溶胶-凝胶法制备了Ce_(0.67)Zr_(0.33)O_2固溶体,并将经和900℃焙烧后的固溶体进行了XRD、BET、Raman、H_2-TPR和储氧量(OSC)表征。结果表明,氧化共沉淀法和柠檬酸溶胶-凝胶法制备的Ce_(0.67)Zr_(0.33)O_2固溶体的储氧量、比表面积均高于均匀共沉淀法,且制备的固溶体经900℃焙烧4 h后未出现相分离,具有良好的热稳定性。     

Peptide Bioconjugates of Electron‐Poor Metallocenes: Synthesis,Characterization, and Anti‐Proliferative Activity

We report the synthesis of metallocene compounds Cp₂M with two different electron‐withdrawing substituents on both cyclopentadienyl rings (hexafluoroacetone (HFA) and chlorobenzoyl ( 1 – 5 ); HFA and COOH ( 6 and 7 ), M=Fe or Ru). The COOH‐containing derivatives were used to synthesize peptide bioconjugates with enkephalin ( 8 and 9 ) and neurotensin ( 10 and 11 ) as well as fluorescein‐labeled neurotensin ( 12 ). All the molecules were fully characterized, including X‐ray structures for 6 and 7 . The physicochemical properties (lipophilicity and electrochemistry) and cytotoxicity on MCF‐7, HT‐29, and PT‐45 cancer cells were evaluated for selected compounds. Electrochemical investigation by cyclic voltammetry revealed that all bis‐substituted metallocenes are up to 300 mV harder to oxidize compared to the monosubstituted 2‐ferrocenylhexafluoropropan‐2‐ol (FcHFA: Δ${E{{{\rm f}\hfill \atop 0\hfill}}}$ =214 mV; disubstituted derivatives: up to Δ${E{{{\rm f}\hfill \atop 0\hfill}}}$ =512 mV; both vs. FcH^0/+). For the bis‐substituted compounds, log P determinations by RP‐HPLC showed increased lipophilicity in comparison to the monosubstituted FcHFA and RcHFA. Cellular uptake was investigated by fluorescence microcopy, and this revealed endosomal entrapment for 12 .     

Structural study of mullite based ceramics derived from a mica-rich kaolin waste

Mullite-based ceramics have been synthesized by reactive sintering of a mixture containing kaolin and a mica-rich kaolin waste. Samples fired in the temperature range from 1300 to 1500 °C were characterized by X-ray diffraction (XRD). The quantitative phase analysis and unit cell parameters of the mullite were determined by Rietveld refinement analysis of the XRD data. Mullite-based ceramics with 1.2 wt% quartz, 56.3 wt% glass (amorphous phase), 2.64 g/cm³ of apparent density, and 35±1.2 MPa of flexural strength were obtained after firing at 1500 °C. A liquid phase sintering mechanism activated by a total mica content of 13.3 wt% allowed to increase the mullite content to 47.6 wt% (2.3 wt% quartz and 50.1 wt% glass phase) and improve the flexural strength (70±3.9 MPa) after firing at 1400 °C.     

Experimental Study of the Heat and Mass Transfer During Drying in a Fluidized Bed Dryer

ABSTRACT

Drying curves obtained in a pilot-scale fluidized bed dryer using biological source solids (sawdust, soya and fish meal) were used to estimate the parameters involved in heat and mass transfer phenomenas: heat transfer coefficient and moisture diffusivity coefficient. Parameters involved in mass transfer were estimated from drying models based on diffusional mechanisms and others that in addition consider internal and external resistance to the mass transfer. The estimate ef ective diffusivity coefficient was between 2x10-11 to lx10 (m2/s) for the considered products. Heat transfer coefficient was estimated from drying data points in the constant drying rate period when the external resistance to the mass transfer controls the process.     

固相研磨反应在缩合反应中的应用

固相研磨有机合成方法比传统的有机合成方法方便,易操作。在研磨条件下许多传统的反应可以在较温和的条件下进行,能有效的提高收率或反应的选择性。本文主要综述了固相研磨反应在Knoevenagel缩合、醇醛缩合、wittig缩合、Biginelli缩合、希夫碱缩合等缩合反应中的应用。     

In_2W_3O_(12)陶瓷的相变特性及其负热膨胀性能(英文)

以分析纯In2O3和WO3为原料,采用固相反应法制备In2W3O12陶瓷。利用X射线衍射仪、场发射扫描电子显微镜、热重分析仪、差示扫描量热仪和热机械分析仪对样品的物相组成、微观结构、相变和热膨胀特性进行了表征。结果表明:在900℃烧结6h可制备出纯的单斜相In2W3O12陶瓷,In2W3O12陶瓷断面晶粒均匀,平均尺寸为4～6μm。In2W3O12陶瓷在253.34℃发生单斜相到斜方相的相转变,单斜相的In2W3O12陶瓷显示正热膨胀,在27～249℃,其平均热膨胀系数为16.51×10-6℃-1,斜方相的In2W3O12陶瓷显示负热膨胀,在273～700℃,其平均热膨胀系数为-3.00×10-6℃-1。