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121.
以HZSM-35、HZSM-5、HM和Hβ四种分子筛为1-己烯骨架异构化催化剂,比较研究了四种催化剂的异构化性能,对其构效关系进行了关联。结果表明,相比于HZSM-5和Hβ分子筛,HZSM-35和HM具有适宜的酸量,有效孔径为0.4-0.6 nm,而且无晶穴、无交叉孔道,具有良好的择形催化效应,在转化率高达95%的同时,C5-和C7+等副产物的收率在20%左右,异己烯收率可达40%-50%。进一步对四种分子筛进行酸碱改性处理,结果显示,虽然酸性质略有改变,但是一维孔结构的HZSM-35和HM分子筛的异构化性能仍明显优于多维孔结构的HZSM-5和Hβ分子筛,说明在酸性质一定的前提下,孔结构对异构化反应起关键作用。 相似文献
122.
针对当前高职分析化学“保姆式”教学模式、学生学习无积极性等问题,依据生态教育理念,以酸碱滴定实验内容为例,从课前准备,课中渗透生态思想,课后学生反思、自查和总结等3个方面进行教学设计,并运用于实践教学中,提升了学生的实验兴趣和应用创新能力,培养了学生的工作责任心,实现了真正的和谐生态课堂。 相似文献
123.
V. V. Semenov E. Yu. Ladilina S. Ya. Khorshev N. P. Makarenko Yu. A. Kurskii O. A. Bochkova 《Russian Chemical Bulletin》1998,47(12):2455-2462
The reaction of (HMe2Si)2NH with Co2(CO)8 gives the complex [Co2(CO)7(SiMe2)2NH2]+[Co(CO)4]−. Its thermal decomposition starts with dissociation into the “acid” HCo(CO)4 and the “base” Co2(CO)7(SiMe2)2NH. After that, the base and the initial complex decompose further under the action of HCo(CO)4. The final products of this reaction are CO, NH3, Co, volatile dimethylcyclosilazane, and a solid residue consisting of cobalt particles encapsulated into a polymethylsiloxane
matrix and possessing properties of mixed para- and ferromagnetics with an ultimate specific magnetization of 64–74 G g−1. Tetramethyldisilazane reacts with iron pentacarbonyl under UV irradiation to give relatively stable 1,3-bis(tetracarbonylthydrideiron)-1,1,3,3-tetramethyldisilazane.
This product contains Fe−H…N hydrogen bonds, which stabilize it against dehydrogenation and cyclization to diironcyclodisilazane.
Thermal decomposition of this product was investigated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2537–2544, December, 1998. 相似文献
124.
Poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) based composite electrolytes for lithium batteries 总被引:1,自引:0,他引:1
A. Manuel Stephan Kee Suk Nahm M. Anbu Kulandainathan J. Wilson 《European Polymer Journal》2006,42(8):1728-1734
The composite polymer electrolyte (CPE) membranes, comprising of poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), aluminum oxyhydroxide, (AlO[OH]n) of two different particle sizes 7 μm/14 nm and LiN(CF3SO2)2 as lithium salt were prepared using solution casting technique. The prepared membranes were subjected to XRD, impedance spectroscopy, compatibility and transport number studies. The incorporation of nanofiller greatly enhanced the ionic conductivity and the compatibility of the composite polymer electrolyte. Also LiCr0.01Mn1.99O4/CPE/Li cells were assembled and their charge-discharge profiles have been made at 70 °C. The film which possesses nanosized filler offered better electrochemical properties than those with micron sized filler. The results are discussed based on Lewis acid-base theory. 相似文献
125.
A. B. Mirgorodskaya N. S. Erzikova L. A. Kudryavtseva A. I. Konovalov 《Russian Chemical Bulletin》2006,55(10):1788-1793
The pK
a values and constants of tautomeric equilibrium of several o-aminomethylphenols with different hydrophilic-lipophilic ability were measured in aqueous micellar solutions and in direct
microemulsions based on cetyltrimethylammonium bromide. The kinetics of hydrolysis of p-nitrophenyl acetate at different pH and concentrations of aminomethylphenol and surfactant was studied.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1724–1729, October, 2006 相似文献
126.
A novel environmentally benign process for the synthesis of methyl N-phenyl carbamate (MPC) from methanol and phenylurea was studied. Effect of solvent and catalyst on the reaction behavior was investigated. The IR spectra of methanol and phenylurea dissolved in different solvents were also recorded. Compared with use of methanol as both a reactant and a solvent, phenylurea conversion and selectivity to MPC increased by using toluene, benzene or anisole as a solvent, while phenylurea conversion decreased slightly by using n-octane as a solvent. The phenylurea conversion declined nearly 50% when dimethyl sulfoxide (DMSO) was used as a reaction media, and MPC selectivity decreased as well. The catalytic reaction tests showed that a basic catalyst enhanced the selectivity to MPC while an acidic catalyst promoted the formation of methyl carbamate and aniline. Moderate degree of basicity showed the best catalytic performance in the cases studied. 相似文献
127.
Effect of acid-base properties on copper catalysts for hydrogenation of carbon dioxide 总被引:1,自引:0,他引:1
Naofumi Nomura Tomohiko Tagawa Shigeo Goto 《Reaction Kinetics and Catalysis Letters》1998,63(1):21-25
Acidic or basic components as co-catalysts were added to the Cu-based catalysts for hydrogenation of CO2. Effects of acid-base properties on the catalytic activity and methanol selectivity are discussed. 相似文献
128.
Using the values of standard molar enthalpy of reaction for dimethylethyleneurea (dmeu),dimethylformamide (dmf), dimethylacetamide
(dma), tetramethylurea (tmu),hexamethylphosphoramide (hmpa) and pyridine (py) with the acids BF3, SbCl5, ZnCl2 and AsCl3, it is shown that, in terms of acid-base behaviour, ZnCl2 is closer to BF3, which differs from SbCl5. Furthermore, the equation −Δr
H
m(ZnCl2) = − [1.26⋅Δr
H
m(BF3)]−56.99 correlates with the standard molar enthalpy of reaction for the same set of molecules with ZnCl2 and BF3. A similar equation was obtained to estimate the enthalpy of reaction with AsCl3: −Δr
H
m(AsCl3) = − [4.12⋅Δr
H
m(BF3)]− 417.82. It is also shown that, for hmpa and tmu, sterical hindrance is a prominent factor that influences the coordination
chemistry of the acidic centres, whose deviation from the linearity can be considered as a measure for the steric contribution
to Δr
H
m.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
129.
P.Darrell Ownby 《Journal of solid state chemistry》2004,177(2):466-470
The separation of the boron isotopes using boron trifluoride·organic-donor, Lewis acid·base adducts is an essential first step in preparing 10B enriched and depleted crystalline solids so vital to nuclear studies and reactor applications such as enriched MgB2, boron carbide, ZrB2, HfB2, aluminum boron alloys, and depleted silicon circuits for radiation hardening and neutron diffraction crystal structure studies. The appearance of this new adduct with such superior properties demands attention in the continuing search for more effective and efficient means of separation. An evaluation of the boron trifluoride nitromethane adduct, its thermodynamic and physical properties related to large-scale isotopic separation is presented. Its remarkably high separation factor was confirmed to be higher than the expected theoretical value. However, the reportedly high acid/donor ratio was proven to be an order of magnitude lower. On-going research is determining the crystal structure of deuterated and 11B enriched 11BF3·CD3NO2 by X-ray and neutron diffraction. 相似文献
130.
Surface properties of poly(cyclopentadiene)–silica hybrid particles (PCPD–silica) were studied by means of XPS and electrokinetic measurements. The surfaces of PCPD–silica particles exhibit two different areas with different properties: bare silica holes and PCPD patches. The PCPD chains contain different functional groups such as alcohol and carbonyl groups that were identified by XPS. The PCPD chains are grafted covalently onto the silica surface via Si–O–C bonds created by the reaction of silanol groups and active PCPD chains. The amount of Si–O–C was examinated by means of XPS. The Brønsted acidity of the residual silanol groups was determined by means of electro-kinetic measurements. It was found that the pK a values of the residual silanol groups increase with increasing polymer content on the particle surface. The surface acceptor strengths of the hybrid particles in non-aqueous liquids were investigated by the solvatochromic indicator bis(1,10-phenanthroline)-cis-dicyano-iron-II in 1,2-dichloroethane. 相似文献