共查询到19条相似文献,搜索用时 78 毫秒
1.
2.
3.
KF/Al2O3在有机合成中的应用 总被引:12,自引:1,他引:11
KF/Al_2O_3在烷基化、羟醛缩合、Michael 加成、Knoevenagel 缩合等有机反应中的应用:讨论了其催化作用的机理。 相似文献
4.
采用原位红外光谱技术,以CO作为探针分子研究了加氢脱硫CoMo/Al2O3-SiO2催化剂的活性吸附位的变化规律。原位硫化温度范围为300~550℃,获得了CoMo/Al2O3-SiO2催化剂的MoS(2110cm2-1)和CoMoS(2070cm-1)活性相在增加硫化温度过程中的转变规律。在CoMo/Al2O3-SiO2催化剂中,当载体中SiO2含量逐渐增加时,能够显著改变催化剂活性相的相对强度变化,表明载体中加入适量的SiO2能够显著改变加氢脱硫CoMo/Al2O3-SiO2催化剂的载体与活性金属(Co和Mo)的相互作用,从而提高金属在加氢催化剂载体上的分散性能,产生更多活性吸附位。 相似文献
5.
6.
《应用化工》2013,(11):2002-2004
以活性氧化铝为载体,制备了Fe/Mn/Al2O3负载型催化剂,用于催化H2O2氧化降解偶氮染料活性黑5,探讨了pH、H2O2投加量、染料初始浓度、催化剂投加量等对染料脱色率的影响。结果表明,活性黑5的脱色率随催化剂投加量、H2O2投加量的增加而升高;而随活性黑5初始浓度的增加而降低。当H2O2投加量的增加达到200 mg/L后,H2O2投加量的增加对活性黑5脱色效果的影响不显著。Fe/Mn/Al2O3/H2O2体系下,活性黑5在pH为29之间均有一定的脱色效果,活性黑5的脱色率随初始pH的增加而先增加后减少,其中在初始pH为3时脱色效果最佳。 相似文献
7.
8.
9.
Ni/Al_2O_3催化剂是甲烷二氧化碳重整反应制取合成气研究最多、最具应用潜力的一种催化剂。通过对催化剂进行CO_2-TPD研究,考察还原态Ni/Al_2O_3催化剂的CO_2脱附特性。结果表明,浸渍法制备的Ni/Al_2O_3催化剂CO_2脱附曲线呈现双峰,分别在(60~65)℃和(350~380)℃出现高低温两个活性位;高温CO_2吸附量为3.0 cm~3·g~(-1),低温CO_2吸附量为24.0 cm~3·g~(-1)。催化剂的CO_2吸附量与其Ni含量无关。考察选用不同载体的CO_2脱附行为,发现以Al_2O_3为载体的催化剂CO_2吸附量是MgO和SiO_2为载体催化剂的2~4倍,以TiO_2为载体的催化剂几乎不吸附CO_2。 相似文献
10.
Fe_2O_3/Al_2O_3催化剂制备及催化降解酸性染料废水 总被引:1,自引:0,他引:1
以γ-Al2O3>为载体,采用浸渍-焙烧法制备了Fe2O3/Al2O3催化剂.并将其用于催化降解模拟酸性大红-3R染料废水.对于质量浓度为1 000 mg/L的高浓度酸性大红-3R染料废水,最佳的处理工艺条件为:温度60℃、pH=3.0、H2O2投加质量浓度9.4g/L、催化剂投加质量浓度1.5 g/L.在此工艺条件下酸性大红染料废水的降解率为99%,CODCr的去除率>83%.而对于质量浓度≤100 mg/L的酸性大红-3R染料废水在此条件下的降解速率接近100%.且催化剂连续使用6次后仍有较高的催化活性. 相似文献
11.
Arie Noomen 《Progress in Organic Coatings》1997,32(1-4):137-142
Since the first filings of patent applications on the use of the Michael addition as crosslinking reaction for coatings around 1984, a lot of research work has been carried out on its application in practical systems. Initial work on the development of coatings for aircraft, car refinishing and timber showed that, especially with urethane acrylate/malonate polyester combinations, the expected high level of durability could be achieved. Further developments in the field of high solids coatings revealed inhibition problems however. They were caused by the interaction of the strong bases, used as the catalysts for the Michael reaction, with acidic ingredients from the substrate and with carbon dioxide from the atmosphere. In principle the problem can be solved by using higher doses of catalyst, but the potlife is too short for general use then. Temporary blocking of the catalysts with an alcohol or with carboxylic acids was investigated as a way to achieve an acceptable potlife. The use of catalysts blocked with carboxylic acids, deblockable with heat or UV light, is a good solution for industrial coatings. Blocking with an alcohol helps to solve the problem of inhibition by carbon dioxide but not the problem of inhibition by the acidic sites in the substrate. 相似文献
12.
13.
14.
15.
Polyethylenimine (PEI) with enhanced fluorescence and thermal sensitivity was achieved by Michael addition of divinylsulfone (DVS) and N-isopropylacrylamide (NIPAm) respectively. The fluorescence enhancement is quantitatively studied by tailoring the amount of DVS, the medium pH, the substituting acrylates, the substrate polymers with different type amine groups, and the substrate molecular weights. The results suggested that different amine groups affected the performance of fluorescence with quantum yields varied from 0.340 for primary amine (NH2-) to 0.090 for tertiary amine (N(-C)3), and further to 0.049 for secondary amine (-NH-). It was also found that the fluorescence enhancement was attributed to the specific molecular structure of DVS-substituted product. The fluorescence moiety is believed to involve a proton-transfer process and have O2-dependent and pH-sensitive fluorescence properties. From the current study, it can be expected that the accurate prediction of the O2-dependent fluorescence would be dependent on molecular orbital calculation of the small amine molecules (oxidized with O2) and their DVS-substituted products. 相似文献
16.
17.
18.
Increased stability in self‐healing polymer networks based on reversible Michael addition reactions 下载免费PDF全文
Natascha Kuhl Robert Geitner Jürgen Vitz Stefan Bode Michael Schmitt Jürgen Popp Ulrich S. Schubert Martin D. Hager 《应用聚合物科学杂志》2017,134(19)
A reversible thiol‐ene click reaction is utilized to design novel self‐healing polymers. These materials are based on a new methacrylate monomer featuring a benzylcyanoacetamide derivative, which is copolymerized with butyl methacrylate. Afterwards, the crosslinking is performed by the addition of a dithiol and a tetrathiol, respectively. Self‐healing behavior is obtained by heating the crosslinked polymers to 100 °C (150 °C) for several hours and is monitored by scratch healing experiments utilizing an optical microscope. The thermal properties are studied in detail by differential scanning calorimetry as well as thermogravimetric analysis. Moreover, depth‐sensing indentation measurements are performed to determine the mechanical properties. The healing process is based on the reversible cleavage/closing of the bonds (i.e., thiol‐ene reaction), which could be demonstrated by Raman spectroscopy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44805. 相似文献
19.
Synthesis and characterization of hyperbranched poly(ester-amine) by Michael addition polymerization
Miao Sun Chunxiao Yin Yanan Gu Yun Li Zhirong Xin 《Designed Monomers and Polymers》2017,20(1):458-467
A series of tertiary amine-based hyperbranched poly(amine-ester)s have been synthesized by Michael addition polymerization of trifunctional monomer, TMEA and difunctional monomer, diacylates in chloroform, and the resultant polymers were subsequently treated with mercaptoethenol or 1-dodecanethiol for improving stability in storage. The caption efficiency of mercaptoethanol is much better than that of 1-dodecanthiol. Kinetic study reveals that the thiol group is consumed faster than the acrylate group when the polymerization with feed molar ratio of diacrylate/TMEA = 2/1 was carried out. At initial polymerization, monomer conversion increases fast, but the molecular weights increase slowly and sharp increase of the molecular weight occurs at the final polymerization. The hyperbranched polymers were well characterized by 1H NMR spectra and TD-SEC, and DBs of the polymers obtained are between 0.6 and 0.82, as well as the molar ratios of diacrylate/TMEA in the hyperbranched polymers are between 1.60 and 1.82. The fluorescence efficiency and quantum yields of HypET20, HypHT24 and HypDT24 has the following sequence: HypET20 > HypHT24 > HypDT24. 相似文献