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1.
壳聚糖固载的四苯基钴卟啉催化空气氧化环己烷   总被引:1,自引:0,他引:1  
黄冠  李喜见  郭灿城 《催化学报》2005,26(9):765-768
 将金属卟啉吸附固载到壳聚糖上,在室温下制备了壳聚糖四苯基钴卟啉催化剂,并用紫外光谱技术测定了四苯基钴卟啉的固载量. 在未加入任何溶剂和还原剂的条件下,研究了壳聚糖四苯基钴卟啉催化空气氧化环己烷的性能. 在418 K和0.8 MPa的空气压力下,壳聚糖四苯基钴卟啉能够很好地催化空气氧化环己烷,环己烷转化率为11%,相应的主产物环己醇和环己酮的选择性为87%,转化数为2.9×105,与未固载的四苯基钴卟啉相比,其催化性能大大提高,环己烷转化率和转化数分别提高了10倍和27倍. 研究结果表明: 壳聚糖对四苯基钴卟啉不仅有明显的保护作用,使之免遭氧化破坏,而且还有重要的助催化作用.  相似文献   

2.
应用3-氯丙基三甲氧基硅烷和咪唑成功地对硅胶表面进行了修饰,并通过咪唑基纵轴配位方式固载了四苯基锰(Ⅲ)卟啉.在无任何外加溶剂及共还原剂的条件下,应用此高分子金属卟啉作为催化剂,选择性地催化空气氧化环己烷为环己酮和环己醇.研究结果表明,与未固载金属卟啉相比,固载金属卟啉具有更高的催化活性和催化选择性,反应具有更高的酮醇比,催化剂的稳定性有了较大的提高,便于回收和重复使用.另外还探讨了载体在此催化体系中对催化性能的影响.  相似文献   

3.
将四(4-硝基苯基)钴卟啉(Co-TNPP)负载在氧化锌(Zn O)载体制备负载型金属卟啉催化剂Co-TNPP/Zn O,并对其进行了紫外-可见漫反射光谱(UV-vis),红外光谱(FT-IR),X射线衍射(XRD),热重分析(TG/DTG),比表面分析(BET)和电感耦合等离子体(ICP)表征.考察了催化剂在无溶剂的条件下催化氧气氧化环己烷的性能.实验结果表明:在反应温度为150℃,氧气压力为1.2 MPa,反应时间为2.0 h的条件下,环己烷转化率9.82%,环己醇和环己酮选择性83.37%.负载型金属卟啉催化剂经过5次循环使用,环己烷的平均转化率和环己醇、环己酮平均选择性分别为9.95%、83.61%,催化剂的平均转化数为2.18×105.负载型金属卟啉催化剂Co-TNPP/Zn O在较温和的条件下表现出优良的环己烷催化氧化性能,克服了金属卟啉催化剂难以回收、无法循环使用的缺点,具有很好的工业价值和应用前景.  相似文献   

4.
金催化剂催化环己烷液相选择氧化研究   总被引:6,自引:0,他引:6  
采用溶胶-凝胶法制备了一系列担载纳米金催化剂,用于催化环己烷液相选择氧化反应.在反应体系中没有加入任何溶剂或助催化剂,考察了反应温度、时间、压力和不同焙烧温度对催化剂活性的影响.实验结果表明,催化剂在250℃焙烧和金含量为0.032%时,环己烷选择氧化可以达到10.8%的转化率和90.8%的目的产物(环己醇和环己酮)选择性,相应转化频率高达5.2×104.  相似文献   

5.
研究了九种μ-氧-双[四苯基卟吩合铁(Ⅲ)]衍生物[TXPPFe~Ⅲ]_2O在温和条件下催化PhIO将环己烷氧化成环己醇和环己酮的反应.结果表明,该反应的产率和速率与卟啉环上取代基的特性常数之间存在线性关系,反应的产物分布和动力学性质与反应温度、溶剂性质以及空气有关.还考察了这一反应过程中的另一竞争反应—氧化剂对[TXPPFe~Ⅲ]_2O的破坏反应.根据文献报道和实验结果,本文对μ-氧-双铁(Ⅲ)卟啉催化环己烷羟基化反应的可能途径进行了探讨.  相似文献   

6.
在pH 10.7,有溴化十六烷基二甲基乙酸铵存在,咪唑催化新显色剂四(邻氯对磺酸基苯基)卟啉与镉和铅反应生成三元胶束络合物,最大吸收波长分别为437和470nm,其表观摩尔吸光系数相应为5.6×10~5和2.0×10~5。用二阶导数分光光度法同时测定镉和铅,结果满意。  相似文献   

7.
高分子多糖载体对四苯基金属卟啉催化性能影响   总被引:2,自引:0,他引:2  
黄冠  刘飞鸽  郭灿城 《化学学报》2006,64(7):662-666
在壳聚糖四苯基金属卟啉中, 氨基或羟基可能对金属卟啉的稳定性和催化活性起重要作用. 为探索这两类基团的作用效果差异, 并调查具有类似壳聚糖结构的纤维素作为载体, 对金属卟啉的保护以及羟基的协助催化作用, 制备了纤维素四苯基铁、钴和锰卟啉. 研究了纤维素四苯基铁、钴和锰卟啉催化空气氧化环己烷的能力, 并与相应的壳聚糖金属卟啉比较. 在418 K和0.8 MPa的空气压力下, 纤维素四苯基铁(钴或锰)卟啉均只能作一次性催化而耗尽; 所获得的醇酮选择性均低于相应的壳聚糖四苯基金属卟啉. 研究结果表明: 纤维素对四苯基铁、钴和锰卟啉没有明显的保护作用, 羟基对其催化环己基过氧化氢的协助分解作用也比较小. 壳聚糖对金属卟啉有很强的保护作用, 氨基有较强的协助金属卟啉催化环己基过氧化氢分解的能力, 使醇酮选择性提高.  相似文献   

8.
研究了银溶胶对2种卟啉化合物——5,10,15,20-四对羟基苯基卟啉(简称T(4-HP)P)和5-羟基苯基-10,15,20-三苯基卟啉(HPTPP)的荧光猝灭行为,在5.0×10~6mol/L的T(4-HP)P,HPTPP溶液中分别加入1.5×10~(-4)mol/L的银胶后,两者的荧光猝灭效率都达90%以上,通过荧光猝灭曲线求得这2种卟啉与银胶之间表观作用常数分别为3.16×10~4(mol/L)~(-1),2.79×10~4(mol/L)~(-1),文中还讨论了银胶对T(4-HP)P,HPTPP荧光猝灭过程的动力学及2种卟啉分子与银胶之间的作用机理.  相似文献   

9.
在无任何外加溶剂及共还原剂的条件下,将金属次卟啉二甲酯应用于催化空气氧化环己烷的氧化反应.结果表明,金属次卟啉二甲酯能够很好地催化环己烷的氧化反应,与简单的金属四苯基卟啉相比,金属次卟啉二甲酯催化剂具有更高的催化活性.进而研究了络合金属对其催化性能的影响.  相似文献   

10.
以交联聚苯乙烯微球(CPS)为基质载体, 采用同步合成与固载的方法, 简捷地制得了固载化阳离子苯基卟啉, 继而通过与钴盐的配合反应, 制备了固载化阳离子钴卟啉. 在此基础上, 以Keggin 型杂多酸磷钨酸(HPW)及磷钼酸(HPMo)为试剂, 凭借阳离子钴卟啉(CoP)与杂多阴离子之间的静电相互作用, 制备与表征了固载化的由阳离子钴卟啉与杂多阴离子复合而成的固体催化剂CoPPW-CPS和CoPPMo-CPS. 将两种复合催化剂用于分子氧氧化乙苯的氧化反应, 考察研究了催化特性. 结果表明: 在分子氧氧化乙苯的氧化反应中, 复合催化剂具有很高的催化活性, 可使乙苯高选择性地转化为苯乙酮, 反应12 h, 苯乙酮的产率达30.1%; 复合催化剂的催化活性比单纯的固载化钴卟啉高75%; CoPPW-CPS的催化活性高于CoPPMo-CPS. 在复合催化剂结构组分中, 固载化的杂多阴离子并无催化活性, 起催化作用的组分是钴卟啉; 但是, 杂多阴离子可有效保护钴卟啉, 使其免于被氧化失活, 从而使其保持稳定的高催化活性. 复合催化剂具有最适宜的投加量, 过量催化剂的加入, 会抑制钴卟啉的催化活性. 复合催化剂还具有良好的循环使用性能.  相似文献   

11.
The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.  相似文献   

12.
非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。  相似文献   

13.
翟宗玺  刘树深  夏树屏 《化学学报》1990,48(10):946-950
用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。  相似文献   

14.
Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.  相似文献   

15.

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

  相似文献   

16.
Cotton cellulose was swollen in a sodium hydroxide solution and carboxymethylated by a two-bath method for different periods of time for each process. The kinetics of acid hydrolysis and the crystallinity of the swollen and carboxymethylated samples were measured. The proportion of broken bonds, rate constants for hydrolysis, and permeability of cellulose to hydrolyzing agents were calculated. The susceptibility of glycosidic linkages to acid hydrolysis was improved by carboxymethylation more than by swelling in alkali. The increased accessibility of carboxymethylcellulose to acid was regarded as a consequence of increased intra-and intercrystalline swelling and of the glycosidic bonds' weakness caused by the electron-attracting carboxymethyl group on the C-6 position.  相似文献   

17.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

18.
In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.  相似文献   

19.
20.
The aim of the presented work was the investigation of thermal oxidation of ilmenite in static air atmosphere. The investigations were carried out by use of a derivatograph (MOM, Hungary). The changes of crystallographic structure of investigated samples were identified by X-ray diffractometry on Philips PW-1710 diffractometer. In temperature above 500°C appears structure of hematite Fe2O3. On the basis of the thermogravimetric measurements, the contracting area and contracting volume models were found as the best fitting experimental data. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

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