分步氟化法合成3,4-二氟苯腈的研究

以3,4-二氯苯腈为起始原料,通过分步氟化,实现了高收率制备3,4-二氟苯腈的方法。相比于先前的报道,本工艺不仅收率提高,同时有效地控制了体系焦化、聚合、变黑等高温下不利因素的影响。     

低温余热驱动的合成氨吸收分离及其与冷凝分离的比较

合成氨分离普遍采用的冷凝分离法不仅能耗高,而且不利于氨合成压力大幅度降低。通过对吸收法分离合成氨过程的模拟,分析了驱动热温度、冷却水温度等条件的影响,并将其火用耗与冷凝分离法进行了比较。吸收分离法有利于利用低温余热,并且可在较大的冷却水温度范围内稳定操作;吸收法分离合成氨的火用耗低,不足冷凝法的三分之二;可利用低温余热代替冷凝法所需的昂贵的电能;虽然其冷却水耗量明显高于冷凝分离法,但其影响较小。在较低的合成压力下,吸收法的分离效果显著优于冷凝法,该过程应用于低压合成氨系统非常有利。     

化学修饰啤酒酵母菌对铀的吸附特性

以甲醛为交联剂, 将胱氨酸修饰到啤酒酵母菌(SC)上, 并采用海藻酸钠和明胶固定化, 得到一种新型的生物吸附剂--修饰啤酒酵母菌(MSC)。通过红外光谱(IR)分别表征了两种吸附剂的结构, 考察了其吸附铀的主要影响因素即溶液pH值、吸附时间等。结果表明: MSC细胞表面具有大量吸附铀的基团, MSC和SC吸附铀的最佳条件是: pH值为6.0, 相似文献   

负载型双金属催化剂催化间苯二甲腈加氢制备间苯二甲胺

采用浸渍法制备活性炭负载Ni、Ru、Rh单金属及Ni-Ru、Ru-Rh双金属催化剂,考察反应温度、反应压力和m(催化剂)∶m(间苯二甲腈)对间苯二甲腈加氢制备间苯二甲胺的影响。结果表明,Ni-Ru/C催化活性高于Ru/C和Ni/C,通过分步浸渍法制备的Ni-Ru/C催化活性优于一步浸渍法。以甲醇和甲苯为混合溶剂,在m(催化剂)∶m(间苯二甲腈)=1∶20、反应温度120℃、反应压力4.0 MPa和1 000 r·min-1条件下,无需加入碱性抑制剂,间苯二甲胺收率最高可达97.78%。     

Preparation of membranes by electropolymerization of pyrrole functionalized by a ferrocene group

The preparation of dense membranes by the electropolymerization of functionalized pyrrole (Py) by ferrocene units was carried out. The synthesis of N‐[3‐(pyrrol‐1‐yl)propyl]ferrocene‐1‐carboxamide (or [(ferrocenyl)amidopropyl] pyrrole, FAPP) is described. The electropolymerization of the monomer on platinum electrode and on stainless‐steel meshes was studied. The electroactivity of the grafted ferrocenyl group of the FAPP monomer was confirmed and the electrochemical properties of the electrogenerated FAPP film were investigated. The stability in potentiostatic and potentiodynamic modes of FAPP films was low and, to improve the latter, the electrochemical preparation of the copolymer between the pyrrole and the FAPP was performed. The electrochemical characterization of the copolymer showed that it was possible to control the oxidation state of both electroactive compounds of the film. The FAPP/Py copolymer was then prepared on stainless‐steel meshes to produce membranes, whose transport properties were electrochemically controllable. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3947–3958, 2004     

Optimal removal of chlorolignin by ultrafiltration achieved by pH control

The ultrafiltration of chlorolignin fractionated from pine kraft pulp bleach effluent originating from the first caustic stage of the bleachery was studied at different chlorolignin concentrations and pH using polysulfone and sulfonated polysulfone membranes.

Retention of chlorolignin increased along with pH and increasing degree of dissociation of chlorolignin, which is a low molecular weight anionic polyelectrolyte. Retention stayed very high, about 99 %, at high pH values. This is remarkable as the chlorolignin molecule is considered to be much smaller than the pore size of the membranes used. The high electrostatic repulsion between the chlorolignin molecules and the membrane surface is obviously the reason for that. Flux reduction decreased remarkably along with pH increase as well.

The results confirm that sufficient chlorolignin removal can be achieved if its ultrafiltration is carried out at pH 10, which is approximately the pH of the first caustic stage in the bleach process.     

Selective oxidation of lupeol by iodosylbenzene catalyzed by manganese porphyrins

Manganese porphyrin-catalyzed oxidation of lupeol by iodosylbenzene was achieved under mild conditions with low isolated yields but with remarkable selectivity, depending on the catalyst of choice. Mn(III) meso-tetraphenylporphyrin and Mn(III) meso-tetrakis(4-carbomethoxyphenyl)porphyrin provided an entry for the preparation of 3β,30-dihydroxylup-20(29)-ene (6–14% yields), whereas Mn(III) β-octabromo-meso-tetrakis(4-carbomethoxyphenyl)porphyrin led to 20-oxo-3β-hydroxy-29-norlupeol (6% yield), as single products. Unreacted lupeol was recovered in quantitative yield. The oxidative transformations at lupeol C20 or C30 take place with no need for protection of C3 hydroxyl moiety.     

乙醇的活性炭吸附及微波解吸

微波辐照再生活性炭是一种很有应用前景的方法。本文测定了微波辐射条件下新炭碘值的变化,研究了吸附了乙醇的活性炭的微波再生条件。通过正交试验,探讨了活性炭再生率与微波功率、载气线速、微波辐照时间、活性炭的吸附量等因素的关系。     

n-Bu2SnO催化酯交换合成碳酸二苯酯的研究

研究比较了 n-Bu2 Sn O、Ti( OC4H9) 4、Al Cl3、Zn Cl2 四种化合物催化酯交换合成碳酸二苯酯 ( DPC)的催化性能 ,其中n-Bu2 Sn O的催化活性最高。在常压下 ,160～ 190℃时 ,n(苯酚 )∶n(碳酸二苯酯 )∶ n( n-Bu2 Sn O) =4∶ 1∶ 0 .0 4,反应时间 14 h,碳酸二甲酯 ( DMC)的转化率为 48.5 % ,DPC的产率为 43 .0 % ,碳酸甲苯酯 ( MPC)产率 5 .5 %。 DPC的选择性 88.7% ,无苯甲醚生成     

稀土氧化物直接法催化合成聚乳酸

研究了用稀土氧化物直接法催化合成聚乳酸。结果表明稀土氧化物均有催化直接合成聚乳酸的效果,且易与产物分离,其中Y2O3的催化性能比其它稀土氧化物效果更好。通过实验得出了以Y2O3为催化剂合成聚乳酸的最佳工艺条件即催化剂用量为乳酸质量0·174%,在120℃,2000Pa下预聚5h,再升温至140℃,1000Pa下反应30h,合成的聚乳酸粘均摩尔质量为8·57×103g/mol。     

Degradation of surfactant solutions by age and by a flow singularity

Four different surfactants were investigated in a closed hydraulic loop in order to find the influence of age of the solution on drag reducing effectiveness and on decrease of critical shear stress. It shows that aging of a particular surfactant is dependent on its concentration. Different sensitivity of solutions to flow disturbances is also shown.     

活性炭催化过氧化氢氧化脱附其表面吸附的二苯并噻吩

主要研究了活性炭催化过氧化氢氧化脱附其表面吸附的二苯并噻吩。比较了使用H₂O₂水溶液,H₂O₂+HCOOH水溶液和H₂O₂+CH₃COOH水溶液对活性炭进行催化氧化再生的性能,并考察了催化条件对活性炭再生性能的影响。结果表明：3种不同的催化氧化再生方法都能使活性炭获得不同程度的再生,其中,使用H₂O₂+HCOOH水溶液进行催化氧化再生的活性炭再生效果最好,达90％以上。使用H₂O₂+HCOOH水溶液对活性炭进行再生时,H₂O₂浓度、HCOOH浓度、反应温度和时间对活性炭再生性能均有影响,选择合适的催化条件,可使再生性能达到最佳。     

球磨制备超细硅酸锆分段磨的实践

对广东佛山顺德盈信超细锆微粉有限公司的生产工艺流程进行了研究,将其原有流程的分级沉砂返回再磨工艺改为分级沉砂小直径研磨介质二段磨工艺,生产试验证实,球磨效率明显提高,磨料粒度D50从3.65 μm降为2.73 μm,D97从24.10 μm降为13.82 μm,球磨时间缩短了1 h,生产成本大幅下降.     

二丁基氧化锡催化酯交换合成硬脂酸异辛酯的研究

以硬脂酸甲酯和异辛醇为原料,二丁基氧化锡(n-Bu2SnO)为催化剂,通过酯交换法合成了硬脂酸异辛酯。考察了反应温度、催化剂用量,反应时间及物料配比等因素对酯交换反应的影响,并考察了催化剂重复使用情况。常压下,反应温度为140℃,n-Bu2SnO与硬脂酸甲酯的摩尔比0.011 4∶1,硬脂酸甲酯与异辛醇摩尔比1∶1.5,反应2 h条件下,硬脂酸异辛酯收率达到89.0%。n-Bu2SnO循环使用5次后,催化活性基本不变。对反应前后n-Bu2SnO的IR和XRD结构表征表明它具有很好的稳定性。     

Removal of volatile organic compounds by cryogenic condensation followed by adsorption

Removal of volatile organic compounds (VOCs) from gaseous effluents by cryogenic condensation and adsorption has been studied. Mathematical models have been developed to predict the extent of removal of a binary mixture of VOCs in air by these two methods under a wide range of operating conditions. The model results are verified with the published work. A model parametric study carried out in this work suggests that if the concentrations of VOCs in the effluent stream vary over a wide range, condensation followed by adsorption is an effective technique to control the emissions. Condensation is found to be suitable if the VOCs emission levels are high (>1%). On the other hand, if the emission levels are low i.e. parts per millions (ppm) or sub ppm, adsorption is a preferred technique for removing the VOCs from the effluent stream. The model results in this work have significance from the perspective of understanding the mechanism of removal of VOCs by these two methods, determining the key operating parameters that control the removal process and also, defining an effective VOC control strategy.     

天然沸石负载壳聚糖用于苦卤脱色的研究

将180~250μm天然沸石用NaOH和HCl洗后烘干,将脱乙酰度为90%的壳聚糖负载在天然斜发沸石上制成复合吸附剂用于海盐苦卤脱色,可脱除苦卤溶液中98%的有色物质。沸石负载壳聚糖在pH<10、投剂量为0. 01g/mL、高速搅拌(300r/min)5min条件下,脱色效果最好。研究了壳聚糖脱乙酰度、壳聚糖浓度、溶液pH和复合吸附剂用量对脱色率的影响。     

离子液体催化苯与环己烯的烷基化合成环己基苯

为了提高苯和环己烯烷基化反应的收率,先考察了不同离子液体对反应的影响,确定以盐酸三乙胺与ZnC l2形成的离子液体为催化剂活性最高,然后考察了它的用量、苯和环己烯的摩尔比、反应时间、原料中的水含量等因素对苯与环己烯烷基化反应的影响。实验结果表明,离子液体的催化活性与其酸强度密切相关,只有在酸性条件下离子液体对苯与环己烯的烷基化反应才有催化活性。在催化剂用量x(离子液体)=4%,n(苯)/n(环己烯)=15、反应温度为80℃及常压反应条件下,环己烯的转化率达100%,环己基苯的选择性可达到89.63%。离子液体催化剂可重复使用,活性基本没有降低。     

Comparison of the properties of clay polymer nanocomposites prepared by montmorillonite modified by silane and by quaternary ammonium salts

In this work, the silylation of sodium montmorillonite (Na⁺-Mt, Nanofil 757®) was performed using (3-aminopropyl)triethoxy silane (APTES). Different reaction conditions were used varying the reaction time and the amount of the aminosilane. Epoxy-based nanocomposites were prepared with different amounts of silylated Mt or commercial organically modified Mt intercalated with stearylbenzyldimethyl ammonium chloride (Nanofil 2®) and distearyldimethyl ammonium chloride (Nanofil 8®), respectively. The grafting/intercalation of the aminosilane inside the Mt interlayer spaces was studied by means of Fourier transform infrared (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and thermogravimetric analysis (TGA). After isothermal curing at 90 °C the Mt epoxy nanocomposites were analyzed by means of XRD and dynamic mechanical analysis (DMA). The glass transition temperature of all prepared nanocomposites containing silylated Mt, is slightly higher than that of the neat epoxy (2 to 5 °C). In the presence of 1 to 5 m% of silylated Mt in epoxy matrix the storage modulus increases from about 5 to 15% at 25 °C, respectively, compared to the pristine epoxy matrix, while only 0–4% increase was observed for epoxy nanocomposites with commercial modified Mt.