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1.
钼基分子筛催化剂,由于不同分子筛的孔道大小及孔道形状不同,对甲烷芳构化反应表现出不同的催化性能,具有8元环孔道结构的小孔ERS-7分子筛没有催化活性,说明甲烷的芳构化反应离不开分子筛孔道作用,较小的孔道中不能生成苯等芳烃,具有10元环孔道结构的ZSM-5,ZSM-11和ZRP-1三种分子筛具有较好的催化性能,但由于其孔道大小及孔道形状的差别在催化行为上表现出一定的差异,具有10元环和12元环孔道结构的MCM-22分子筛,尤其对对苯等轻芳烃而言,催化性能最佳,具有12元环孔道结构的JQX-1以及中孔分子筛SBA-15,虽然上有一定的催化性能,但活性较低,研究结果表明,孔道大小,与苯分子动态直径相近或孔道稍大的分子筛是催化甲烷芳构化反应的良好载体,孔道过大或过小都不利于苯和萘等烃的生成。  相似文献   

2.
沸石负载的钒络合物催化剂对烷烃氧化反应的催化性能   总被引:6,自引:0,他引:6  
 将钒氧吡啶甲基络合物VO(pic)2负载于Y及ZSM-5沸石分子筛\r\n中,制备出沸石负载的钒络合物催化剂.用X射线衍射、电子自旋共振\r\n、红外光谱和元素分析等方法对催化剂进行了表征.结果表明,VO(p\r\nic)2络合物确实负载于分子筛孔道内,负载后的络合物仍保持着原来\r\n的结构.考察了催化剂对正己烷和环己烷氧化反应的催化性能,发现沸\r\n石分子筛负载的VO(pic)2络合物催化剂保留有络合物原有的催化性能\r\n,虽然催化活性有所下降,但显示出较好的形状选择性.与未负载的络\r\n合物相比,NaY和ZSM-5沸石负载的VO(pic)2络合物催化剂对正己烷\r\n氧化反应的伯醇选择性分别提高了2~3倍和5~6倍.  相似文献   

3.
锌含量对Zn/HZSM-5催化剂性能的影响   总被引:13,自引:2,他引:11  
 研究了不同锌含量的Zn/HZSM-5分子筛的表面酸性及其对正己\r\n烷芳构化反应的催化活性、选择性和稳定性.结果表明,锌组元的引入\r\n减少了HZSM-5表面的B酸,增加了L酸,总酸量增大;正己烷转化率随\r\n锌含量的增加先降低后升高;芳烃产率和芳构化选择性则随锌含量的增\r\n加先增大后趋于平缓;反应过程中催化剂的积炭速度、孔体积和比表面\r\n积下降速度都随着锌含量的增加而加快;锌含量大于1%时,Zn/HZSM\r\n-5的催化稳定性不如HZSM-5,且随着锌含量的增加失活速度加快.优\r\n选的锌含量为1.0%~2.9%.此外,讨论了Zn/HZSM-5的催化性能\r\n与其表面性质的关系.  相似文献   

4.
研究了反应温度、空速、Mo担载量和焙烧温度对MoO3/HZSM-5催化剂上甲烷的芳构化反应的影响.HZSM-5分子筛的Bronsted酸性、孔道结构和Mo在分子筛中的分布是影响催化性能的重要因素.HZSM-5上Mo担载量为2~3%时活性最佳,在1013K反应温度下甲烷转化率可达9%,芳烃选择性大于90%.空速影响的实验表明乙烯是反应的初始产物.在此基础上提出了"甲烷酸助异裂活化"的新概念、"金属钼类碳烯中间物"的新观点和甲烷芳构化的可能机理.  相似文献   

5.
考察了三种不同结构的分子筛(ZSM-5,MCM-22及-β)以及不同晶粒大小的ZSM-5分子筛对环己烯水合反应的催化活性。结果表明,具有12元环孔道体系的β分子筛对环己烯的转化率(9.6%)最高,但对环己醇的选择性(35.4%)最差。MCM-22分子筛的活性很低,其环己烯转化率只有0.8%。而孔口为10元环结构的ZSM-5分子筛则具有较高的活性环己烯转化率7.5%)和产物选择性(99.2%),因此是较好的水合催化剂。ZSM-5分子筛的晶粒大小对其环己烯水合反应活性有明显的影响,分子筛晶粒越细,则水合反应活性越高,其原因大于晶粒变细增大了分子筛的外比表面积,从而增加了接近孔口处的活性中心的数量。  相似文献   

6.
钛硅分子筛TS-1催化氯丙烯环氧化反应动力学研究   总被引:9,自引:0,他引:9  
 摘要:研究了钛硅分子筛催化氯丙烯环氧化反应的条件及动力学行为.\r\n结果表明,以钛硅分子筛为催化剂,氯丙烯可被高选择性地氧化为环氧\r\n氯丙烷.环氧化反应速度与分子筛中骨架钛的含量及分子筛的用量呈正\r\n比关系,是一级反应.对于氧化剂H2O2,只有当c(H2O2)<0.4mol/\r\nL时,环氧化反应为一级反应;而c(H2O2)>1.0mol/L时,为零级反\r\n应.对于氯丙烯,随着其浓度的变化,环氧化反应的级数在1和0之间.\r\n然而,只有当氯丙烯浓度很高时,环氧化反应的级数才有明显的降低.\r\n根据实验结果和Eley-Rideal单分子吸附方程,提出了氯丙烯环氧化反\r\n应的动力学模型.\r\n关键词:钛硅分子筛,氯丙烯,过氧化氢,环氧化,环氧氯丙烷,反应\r\n动力学  相似文献   

7.
晶化时间对ZSM-5分子筛物化性质及催化性能的影响   总被引:5,自引:1,他引:4  
 考察了ZSM-5分子筛在晶化过程中的变化规律及其在苯与乙烯气相烷基化制乙苯反应中的催化性能.结果表明,当晶化时间为70h时,分子筛晶体开始出现;晶化90h时无定形物相基本消失.晶化时间从90h再延长至150h,ZSM-5分子筛晶粒的大小、形貌和体相硅铝比都基本不变,但分子筛表面的硅铝比逐渐降低.以晶化时间为90h的ZSM-5分子筛原粉为活性组元制备的催化剂,对苯与乙烯气相烷基化制乙苯反应表现出最佳的催化性能.  相似文献   

8.
Re/HZSM-5体系上的甲烷无氧芳构化反应   总被引:1,自引:0,他引:1  
 与Mo/HZSM-5相比,Re/HZSM-5也是较好的甲烷无氧芳构化催\r\n化剂,其初活性较高,但随着反应的进行,催化剂失活的速率较快.通\r\n过NH3-TPD,H2-TPR和MASNMR等手段,对催化剂的酸性和分子筛骨架\r\n铝的变化以及铼物种的还原性能进行了研究.结果表明,催化剂酸性的\r\n在反应中起着重要的作用,但不同铼担载量的催化剂酸性的变化比较复\r\n杂,不同于Mo/HZSM-5体系.总的来看,并不是酸性越强或酸量越多\r\n,催化剂的催化性能就越好;催化剂的酸性和酸量都有一个最佳值.担\r\n载铼物种后,铼物种可与分子筛的骨架铝发生强烈的相互作用,最终导\r\n致骨架脱铝.Re/HZSM-5催化剂具有较高的低温活性,在较低温度下\r\n可被还原性气氛还原,且还原后的活性物种单一.  相似文献   

9.
甲烷在MoO3/HZSM-5分子筛催化剂上的非氧催化转化   总被引:14,自引:3,他引:14  
研究了反应温度、空速、Mo担载量和焙温度对MoO3/HZSM-5催化剂上甲烷的芳构化反应的影响。HZSM-5分子筛的Bronsted酸性、孔道结构和Mo在分子筛中的分布是影响催化性能的重要因素,HZSM-5上Mo担载量为2-3%时活性最佳,在1013K反应温度下甲烷转化率可达9%,芳烃选择性大于90%,空速影响的实验表明乙烯明反应的初始产物,在此基础上提出了“甲烷酸助异裂活化”的新概念、“金属相类  相似文献   

10.
 合成了结构类似于MCM-22分子筛超笼孔系的、具有10元环和12元环交叉孔道结构且12元环通过10元环与分子筛外表面相连的二维高硅分子筛NU-87,利用XRD,SEM,N2吸附及NH3-TPD等手段对其物理化学性质进行了表征. 结果表明,合成的HNU-87分子筛晶体结构中存在两种微孔结构,且具有与HMCM-22分子筛非常相似的酸性. 考察了6%Mo/HNU-87对甲烷无氧芳构化反应的催化性能,发现合成的HNU-87分子筛不是甲烷无氧芳构化催化剂的良好载体. 6%Mo/HNU-87催化剂的催化活性和稳定性都比较差. 积炭是主要产物,其选择性高达60%.  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.

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   

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.
针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。  相似文献   

16.
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   

17.
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   

18.
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   

19.
袁丽秋 《化学教育》2006,27(5):8-10
面对日益枯竭的能源危机,氢能是一种洁净、最有前景的替代能源。目前在各种制氢的方法中光催化分解水制氢的研究最多,光解水过程中催化剂最关键,本文对利用太阳能光解水的途径、提高光催化反应效率以及光催化剂的开发研究进行了综述。  相似文献   

20.
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