共查询到20条相似文献,搜索用时 265 毫秒
1.
《化学工业与工程技术》2016,(3):72-74
以邻二氯苄为原料,在乙醇/水体系中经过Na_2CO_3水解,合成了邻苯二甲醇。考察了水醇体积比、反应原料摩尔比、反应时间以及反应温度对产品收率的影响,确定了最佳反应条件。通过红外光谱对产物进行了结构表征,利用高效液相色谱测定了产品的纯度。结果表明:在水醇体积比5∶1的体系中,在反应时间8 h、反应温度90℃、邻二氯苄与无水碳酸钠摩尔比为1∶1.3的最佳反应条件下,合成的邻苯二甲醇收率可达86%,纯度(w)达98%。该工艺操作简单、反应条件温和、成本低,有利于工业化生产。 相似文献
2.
3.
4.
以苯酐和尿素为反应原料,通过微波辐射合成了邻苯二甲酰亚胺.结果表明:微波辐射法的反应速率显著提高,辐射反应100s,收率达85%,产品纯度为95%.同时考察了微波辐射时间、功率、原料配比以及输入能量对反应收率的影响,发现以苯酐和尿素为原料微波合成邻苯二甲酰亚胺的最佳反应条件为:苯酐:尿素耦1:1:2(摩尔比),每克苯酐输入的表观辐射能为11.35kJ,采用连续辐射方式。 相似文献
7.
介绍了邻二氟苯两种新的制备方法,即选择邻氟苯胺作为原料(1)在HCl/NaNO2中进行重氮化反应,然后与氟硼酸反应,生成的氟硼酸重氮盐,再在氯代芳烃中加热分解,得到所需产品。(2)在HF/吡啶中加入NaNO2进行重氮化反应,然后再加入氟化氢来降低碱浓度后进行光解,得到所需产品。 相似文献
8.
9.
10.
11.
12.
13.
Chunlei Shi Arden B. Walters M. Albert Vannice 《Applied catalysis. B, Environmental》1997,14(3-4):175-188
Dispersing La2O3 on δ- or γ-Al2O3 significantly enhances the rate of NO reduction by CH4 in 1% O2, compared to unsupported La2O3. Typically, no bend-over in activity occurs between 500° and 700°C, and the rate at 700°C is 60% higher than that with a Co/ZSM-5 catalyst. The final activity was dependent upon the La2O3 precursor used, the pretreatment, and the La2O3 loading. The most active family of catalysts consisted of La2O3 on γ-Al2O3 prepared with lanthanum acetate and calcined at 750°C for 10 h. A maximum in rate (mol/s/g) and specific activity (mol/s/m2) occurred between the addition of one and two theoretical monolayers of La2O3 on the γ-Al2O3 surface. The best catalyst, 40% La2O3/γ-Al2O3, had a turnover frequency at 700°C of 0.05 s−1, based on NO chemisorption at 25°C, which was 15 times higher than that for Co/ZSM-5. These La2O3/Al2O3 catalysts exhibited stable activity under high conversion conditions as well as high CH4 selectivity (CH4 + NO vs. CH4 + O2). The addition of Sr to a 20% La2O3/γ-Al2O3 sample increased activity, and a maximum rate enhancement of 45% was obtained at a SrO loading of 5%. In contrast, addition of SO=4 to the latter Sr-promoted La2O3/Al2O3 catalyst decreased activity although sulfate increased the activity of Sr-promoted La2O3. Dispersing La2O3 on SiO2 produced catalysts with extremely low specific activities, and rates were even lower than with pure La2O3. This is presumably due to water sensitivity and silicate formation. The La2O3/Al2O3 catalysts are anticipated to show sufficient hydrothermal stability to allow their use in certain high-temperature applications. 相似文献
14.
研究了头孢托仑匹酯关键中间体4-甲基-5-噻唑甲醛(1)的合成新工艺.以乙酰乙酸甲酯(2)为起始原料,首先进行α-溴代反应、与硫脲缩合反应,制得2-氨基-4-甲基-5-噻唑甲酸甲酯(3),收率高达96%;其次用廉价的次亚磷酸钠(1.5当量)替代次亚磷酸,进行氨基重氮化还原反应,制得4-甲基-5-噻唑甲酸甲酯(4),收率为75%;最后用硼氢化钾/氯化锂体系(1.5当量)在回流的无水乙醇中进行酯还原反应,所得粗产物不经分离提纯,直接用次氯酸钠(2.0当量)氧化得到目标化合物,收率为62%,反应总收率在44%以上.该过程条件温和,操作简便,后处理简单,具有工业化应用前景. 相似文献
15.
Hyuk Kim Dae Won Park Hee Chul Woo Jong Shik Chung 《Applied catalysis. B, Environmental》1998,19(3-4):233-243
Mixed oxides of Co3O4–TiO2 have shown the highest catalytic activity for the reduction of SO2 by CO among catalysts that have been developed so far. Almost zero conversion was observed with cobalt alone, whereas a high conversion was obtained with TiO2 especially at high temperatures. There existed a strong synergistic promotional effect in the conversion of SO2 when cobalt was mixed with TiO2. The synergistic effect observed with mixed oxides is caused by simultaneous contributions from two different reaction routes via COS intermediate mechanism and modified redox mechanism. The synergistic effect that is caused by the COS mechanism has a smaller amount of contribution in the conversion increase and remains almost constant with an increase in the reaction temperature. A larger portion of the synergistic effect is contributed from the modified redox mechanism especially at low temperatures, but the effect disappears at temperatures above 450°C. It is found that the introduction of cobalt into TiO2 produces COS by the reaction between sulfided CoS2 and CO even at low temperatures. The COS intermediate can react with SO2 to produce an additional sulfur via the COS intermediate mechanism, and also behaves as a strong reductant to keep oxygen vacancies on the TiO2 in a high concentration for the production of sulfur via modified redox mechanism. 相似文献
16.
17.
P. Rutkowski 《Fuel Processing Technology》2011,92(3):517-522
The chemical structure of liquid products of the wood biopolymers, i.e. cellulose, xylan and lignin pyrolysis at 450 °C with and without the 10 wt.% addition of potassium carbonate or zinc chloride was investigated. The yield of liquid products of pyrolysis was in the range of 24-44 wt.% and their form was depending on the chemical structure of pyrolyzed material. The potassium carbonate and zinc chloride addition to biopolymers has also influenced the temperature range of samples decomposition as well as the structure of resulted bio-oils. All bio-oils from biopolymer were dark-brown water-oil emulsions. Contrarily, bio-oils obtained from biopolymer with K2CO3 or ZnCl2 addition were orange liquids with well-separated water and oil phases. All analyses proved that the composition and the quality of bio-oil strongly depends on both the nature of the starting sample and the presence of the additive. The FT-IR analyses of oils showed that oxygen functionalities and hydrocarbons contents highly depend on the type of biopolymer. Results confirmed the significant removal and/or transformation of oxygen containing organic compounds due to the zinc chloride and potassium carbonate presence during pyrolysis process. 相似文献
18.
以苯甲醛和1,2-丙二醇为原料,在固体超强酸SO24-/ZrO2催化下合成了苯甲醛缩1,2-丙二醇,考察了物料配比、反应时间、催化剂用量、带水剂用量等因素对反应的影响。结果表明,固体超强酸SO24-/ZrO2对合成苯甲醛缩1,2-丙二醇具有良好的催化活性,在苯甲醛用量为0.15mol、n(苯甲醛)∶n(1,2-丙二醇)为1∶1.3、反应时间为60min、催化剂SO24-/ZrO2用量为反应物总质量的0.9%、带水剂环己烷用量为20mL的最佳合成工艺条件下,苯甲醛缩1,2-丙二醇的收率达95.62%、纯度大于99.0%。 相似文献
19.
尖晶石CoAl2O4光催化还原CO2的研究 总被引:1,自引:1,他引:1
采用无机盐溶胶-凝胶法制备了CoAl2O4纳米粉体,用紫外-可见分光光度计(UV-Vis)、X射线衍射光谱仪(XRD)和扫描电子显微镜(SEM)对其光电活性、晶体结构和形貌进行了表征。结果表明,所制备催化剂属尖晶石结构,颗粒呈近球形和不规则形状,粒子尺寸约4.39 nm,光吸收极限波长大于800 nm,计算得到禁带宽度Eg1.55 eV。在高压汞灯照射下,分别选用K2C2O4、NaHSO3和NaH2PO2为供电子试剂,进行了光催化还原CO2制取甲酸的研究。结果表明,在选用NaHSO3的情况下,CoAl2O4的催化效果最好,光照4 h,甲酸产量达到4004.16μmol/g-Cat。 相似文献
20.
研究了在维生素B1催化下,以无水乙醇为溶剂,1,8-二氨基萘与丁酮反应合成2-乙基-2-甲基-2,3-二氢-1H伯啶的反应,考察了催化剂用量、反应物摩尔比、反应温度、时间等因素对产品收率的影响。结果表明,在电磁搅拌下,当1,8-二氨基萘用量为0.1 mol,丁酮与1,8-二氨基萘的摩尔比在1.2∶1,催化剂用量为2.0%,反应温度为35℃,反应30 min时,最佳产品收率可达到85.2%。维生素B1对该反应具有良好的催化作用,是合成2-乙基-2-甲基-2,3-二氢-1H伯啶的良好催化剂。产品经熔点、红外光谱进行了表征。 相似文献