负载型CuO—ZnO／γ—Al2O3催化剂抗硫中毒性能的研究

采用XPS、TPR法证明浸渍法制备的CuO-ZnO/Al_2O_3催化剂中的CuO、ZnO和γ-Al_2O_3之间存在强相互作用,Cu量≤7.0wt%,Zn量≤11Wt%时,CuO和ZnO以单分子层分散在γ-Al_2O_3上.催化剂表面Cu和Zn实际含量的比值远小于配制时的比值(Cu/Zn=2),表明ZnO比CuO优先分布在表面.因ZnO比CuO更易和S作用生成ZnS,ZnO在表面的大量存在减少了Cu被S中毒的机率;另外CuO单层分散在Al_2O_3上,还原后生成的Cu~0,由于γ-Al_2O_3的拉电子作用使其处于缺电子状态(CU~(?+)),加上催化剂表面可能有部分CuO和Al_2O_3形成尖晶石,使一部分Cu以Cu~(n+)存在,Cu~((?)+)或Cu~(n+)对S的吸附弱.以上两个原因使负载型铜催化剂具有良好的抗硫中毒性能.     

Redox Transformation of Adducts from Cycloaddition of Diazoacetic Ester to β-Arylacryloyloxiranes

It was established that, in addition to ethyl 4-aryl-3-(2,3-epoxyalkanoyl)-4,5-dihydro-1H-pyrazole-5-carboxylates, the reaction of diazoacetic ester with β-arylacryloyloxiranes also gives ethyl 4-aryl-3(5)-(3-hydroxy-2-methylalkanoyl)-1H-pyrazole-5(3)-carboxylates. The latter are formed from the tautomeric ethyl 4-aryl-5-(2,3-epoxyalkanoyl)-4,5-dihydro-1H-pyrazole-3-carboxylates as a result of intramolecular oxidative-reductive disproportionation. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, 1150–1160, August, 2005.     

STABILITY OF POLY（N,N＇-METHYLENEBISACRYLAMIDE-co-4-VINYLPYRIDINE） MICROGEL DISPERSION AND ADJUSTMENT OF THE HYDROPHOBICITY IN THE MICROGELS

In the UV-Vis spectra of pure light-scattering systems, there is an exponential relationship between absorbance and wavelength （A = Kλ^-n）. Here, the exponent n is named as flocculation-coagulation parameter. In the present paper, the effects of different additives on the stability of poly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine） （poly（Bis-co-4-VP）） microgel dispersion were studied in detail via this parameter. The results showed that the stability of the dispersion mainly comes from the ionization of pyridine groups, making the microgel positively charged on its surface. This was confirmed by the measurement of Zeta potential and the result of conductometric titration. The result of fluorescence analysis indicated that the hydrophobicity in the microgels is enhanced with the increase in total 4-VP unit content.     

Synthesis of New Fluorinated Derivatives of Quinolinecarboxylic Acids

Ethyl esters of 1-(7-Z-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carbamoyl)-5-X-6,7,8-trifluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acids (X = H, F; Z = pyrrolidino-, piperidino-, hexamethylenimino-, morpholino-, thiomorpholino-) have been synthesized by the interaction of quinolone-3-carboxylic acid hydrazides with ethyl esters of 3-ethoxy-2-(polyfluorobenzoyl)acrylic acid . It was shown possible to cyclize intramolecularly the esters obtained with the formation of 1,3,4-oxadiazino[6,5,4-i,j]quinoline derivatives.     

含离子液体［bmim］Cl的反应介质中马肝醇脱氢酶的催化特性

 研究了马肝醇脱氢酶(HLADH)在含离子液体1-丁基-3-甲基咪唑氯酸盐(［bmim］Cl)的反应介质中的催化特性. 以乙醇为底物时,该酶在［bmim］Cl含量≤0.15 g/ml的体系中的活力高于在不含离子液体的体系中的活力; 离子液体浓度过高(＞0.15 g/ml)对酶活性有明显的抑制作用. 反应温度和pH对含离子液体的反应介质中酶活力的影响规律与不含离子液体时的规律相似. 与不含离子液体的反应介质相比, HLADH在含0.05 g/ml ［bmim］Cl的体系中催化乙醇氧化的活化能下降,酶反应的Vmax和Km均升高. 反应体系中低浓度(≤0.1 g/ml)的离子液体能提高酶的热稳定性,但高浓度(＞0.1 g/ml)的离子液体可降低酶的热稳定性. 紫外二阶导数光谱显示,在含不同浓度离子液体的反应介质中酶分子构象的变化有较大的差异.     

Operating characteristics and energy distribution in transferred plasma arc systems

A specially designed plasma chamber was constructed to study the operating characteristics of a dc plasma-transferred arc of argon, struck between a fluid convective cathode and a water-cooled anode. The arc voltage increased markedly with arc length and with an increase in the inlet velocity of the argon flow past the cathode tip, and much less with an increase in current. Radiation from the plasma column to the chamber walls and transfer of energy to the anode were the two principal modes of transfer of the arc energy. The former was dominant in the case of long arcs and at high inlet argon velocities. At the anode, the major contribution was from electron transfer, which occurred on a very small area of the anode (～5 mm in diameter). Convective heat transfer from the plasma was somewhat less. In all cases, the arc energy contributions to cathode cooling and to the exit gas enthalpy were small. From total heat flux and radiative heat transfer measurements, it was estimated that the plasma temperature just above the anode was in the range 10,000–12,000 K. Preliminary experiments with an anode consisting of molten copper showed that the arc root was no longer fixed but moved around continuously. The arc was othwewise quite stable, and its operating characteristics differed little from those reported for solid anodes, in spite of the greater extent of metal vaporization.     

某些有机物在氧化物载体表面的自发单层分散

自发单层分散原理已在载负型催化剂制备、再生等方面得到越来越广泛的应用[1，2]．许多氧化物和盐类可以在载体表面形成单层分散或亚单层分散．有些分散物与载体混合后在低于其熔点的温度下处理，就可以自发分散到载体表面[1，3]．这一现象通过XRD、LRS、XPS、SIMS、ISS、EXAFS     

A critical reappraisal of recent communications on the hydrodynamic characterization of silica (aerosil) hydrosols

Different results from recent communications on the hydrodynamic characterization of ultrasonicated silica (®Aerosil) hydrosols led to a critical reappraisal of the data.It can be concluded that the degree of dispersion achievable in pyrogenic (Aerosil) hydrosols by ultrasonication is highly sensitive to the detailed parameters of the dispersion process. Characterization in terms ofabsolute numbers of a limiting particle morphology, corresponding to minima of aggregate size, porosity and number of primary particles in the aggregate is not possible.The most straightforward approach for hydrodynamic characterization seems to be a combination of sedimentation and diffusion data.Other approaches using a combination of sedimentation and viscosity data underestimate the particle dimensions. Moreover, they are quite arbitrary since the final result depends upon the proper choice between several equations for fitting the viscosity concentration dependence; the most rigorous approach seems to be an extended Einstein equation which has recently been adapted to particle aggregates.     

内蒙古地区天然植物沙棘果中黄色素的提取工艺及性质研究

以内蒙古地区沙棘果实为原料，研究了提取黄色素的工艺条件，同时对该色素的性质进行了初步探讨。结果表明，以95％的乙醇溶液作浸提剂，提取的黄色素浓度最高，工艺流程简单易行，且无毒，无污染。对提取的黄色素进行的性质试验表明，沙棘黄色素对光、热具有较好的稳定性，适用于酸性或弱碱性的食品中，葡萄糖、氧化剂(H2O2)、还原剂(Na2SO3)等食品添加剂均无明显影响以上结果为这种优良天然色素的开发与应用提供了参考。