己二酸的清洁催化氧化合成研究进展

综述了近年来以环己烯、环己酮、环己醇或环己烷等作原料,以过氧化氢或氧气等为氧源,采用不同的催化体系清洁合成己二酸的新进展.指出:在这些方法中,改性的分子筛及负载型催化剂-双氧水体系将是今后己二酸清洁合成的重点研究方向.     

月桂酸缩水甘油酯的相转移催化合成与表征

目的研究月桂酸缩水甘油酯的有效合成、纯化方法,为食用油脂中脂肪酸缩水甘油酯的检测提供相关对照品。方法以月桂酸钠和环氧氯丙烷为起始原料,四丁基溴化铵为催化剂,采用相转催化法一步合成了月桂酸缩水甘油酯,通过甲醇/正己烷为萃取溶液及重结晶的方式得到纯品。纯化后的产物经高效液相、红外光谱、元素分析、质谱等手段进行表征。结果产物经表征后确证为月桂酸缩水甘油酯,在优化条件下产物的纯度可达95%以上,符合标准对照品的纯度要求。结论该方法以环氧氯丙烷为反应物和溶剂,原料易得、成本低廉,反应效率高、操作简便,为脂肪酸缩水甘油酯的合成提供了一种有效途径与方法。     

催化氧化合成葡萄糖酸钾工艺技术研究

以葡萄糖为原料，用Pd-Bx／C作催化剂，通过催化氧化的方法，合成了葡萄糖酸钾，产品收率97.8％。探讨了催化剂、葡萄糖质量浓度、氧气量、搅拌参数对葡萄糖转化率的影响。     

脂肪酸单甘油酯的酶催化合成及其表征

以癸酸甲酯、月桂酸甲酯、肉豆蔻酸甲酯、棕榈酸甲酯和硬脂酸甲酯为原料,与甘油进行脂肪酶催化酯交换反应制备脂肪酸单甘油酯,产物为脂肪酸单甘油酯和少量脂肪酸双甘油酯的混合物,其中脂肪酸单甘油酯的质量分数均在91%以上,最高可达95.9%。随着碳链长度的增加,脂肪酸甲酯的转化率降低,脂肪酸单甘油酯的质量分数也降低。采用气相色谱-质谱联机、核磁共振氢谱和红外光谱,对柱层析分离后的脂肪酸单甘油酯进行了结构表征。     

Heterogenous and homogenous catalytic oxidation by supported gamma-FeOOH in a fluidized-bed reactor: kinetic approach

Oxidation of benzoic acid (BA) by H2O2 was performed with a novel supported gamma-FeOOH catalyst in a circulating fluidized-bed reactor (CFBR). This study focused mainly on determining the proportions of homogeneous catalysis and heterogeneous catalysis in this CFBR. Also studied herein was how pH, H2O2 concentration, and BA concentration affect the oxidation of BA. Experimental results indicate that the decomposition rate of H2O2 was proportional to its concentration and that the oxidation rate of BA depended on both H2O2 and BA concentrations. The change in the rate constant of heterogeneous catalysis by pH was described in terms of ionization fractions of surface hydroxyl group. From the mathematical deduction, we can infer thatthe reaction rate associated with ...Fe(III)OH2+ is markedly higher than that with ...Fe(III)OH. Conclusively, although heterogeneous catalysis contributes primarily to the oxidation of BA at pH 4.4-7.0, the homogeneous catalysis is of increasing importance below pH 4.4 because of the reductive dissolution of gamma-FeOOH.     

介孔SO2-4/ZrO2的制备、表征及其催化 煎炸废油合成生物柴油

采用溶胶凝胶法,使用十六烷基三甲基溴化氨（CTAB）为模板剂,正丙醇锆为锆源,（NH4)2SO4为硫化剂,经不同温度（400～600 ℃）煅烧制备介孔SO2-4/ZrO2固体超强酸。并利用氨程序升温脱附（NH3-TPD）、傅里叶红外光谱（FT-IR）、N2物理吸脱附（BET）、X射线衍射（XRD）和透射电子显微镜（TEM）对样品结构进行表征。结果显示：当煅烧温度为500 ℃时制备的催化剂出现明显的四方晶相,随着煅烧温度的升高,催化剂的比表面积先增加后减小,500 ℃时最大,比表面积为130 m2/g,孔径为3.3 nm;TEM显示所制备的催化剂均具有蠕虫状介孔结构;NH3-TPD曲线显示所制备的催化剂均具有超强酸性,500 ℃时酸量最大,为22 cm3/g STP。将该催化剂用于煎炸废油和甲醇酯交换制备生物柴油试验,发现500 ℃煅烧的催化剂具有较高的催化活性,于190 ℃下反应8 h生物柴油收率达到92.3%。催化剂重复利用5次后,生物柴油收率仍能达到76.3%。     

HZSM-5/Y复合分子筛的制备、表征及催化裂化性能研究

以商用HZSM-5分子筛为母体,采用NaOH溶液对其进行预处理,在添加铝源和Y导向剂的作用下合成了HZSM-5/Y复合分子筛,并对其进行XRD、SEM和BET表征。考察了NaOH溶液浓度对复合分子筛结构和形貌的影响。进一步考察了该复合分子筛催化剂在油酸裂化反应中的催化特性,并与商用HZSM-5分子筛的催化特性作了比对。结果表明:当NaOH溶液浓度为1. 5mol/L时制备的HZSM-5/Y复合分子筛具有良好的分子筛结构,并且在催化裂化反应中表现出良好的性能。当使用该分子筛时,在反应温度475℃、质量空速6. 99 h-1条件下,液体产物产率达到了54. 2%,油酸脱氧率为38. 5%,液体产物酸价(KOH)为2. 6 mg/g;与使用商用HZSM-5分子筛相比,该复合分子筛对5~12个碳原子的链烃类的选择性更高,其裂化液体产物酸价更低,但重复使用效果较差。     

Mechanism and kinetics of the catalytic oxidation of aqueous ammonia to molecular nitrogen

Aqueous phase catalytic oxidation of ammonia has been studied over Ru/TiO2 catalyst in a batch reactor by changing the solution pH, concentration of catalyst in the solution, temperature, and reaction time. The oxidation reaction of ammonia over Ru/TiO2 catalyst has been found to take place exclusively for the aqueous NH3 with a preferred mode in strong alkaline pH region. An oxidation reaction pathway has been proposed as follows: Oxidation of ammonia is initiated by the reaction of aqueous ammonia with catalytically activated oxygen. After undergoing further successive oxidation reactions with activated oxygen, ammonia is finally oxidized to a molecule of nitrous acid. Nitrous acid dissociates into a nitrite ion and a proton. The solution pH is decreased with the protons from the dissociation of HNO2 so that the solution concentration of NH4+ is increased. Molecular nitrogen as a final product is produced from the homogeneous aqueous phase reaction between nitrous ion and ammonium ion. Further reaction of nitrous ion with the activated oxygen leads to the formation of nitrate ion. The reaction pathway proposed has been validated with the changes of solution pH along with the ammonia conversions, and the formation of N2 from the solution containing NO2- and NH4+ ions in equimolar amounts of nitrogen has been confirmed in a separate experiment. The kinetics of aqueous ammonia oxidation reaction has been well represented as a first-order reaction with respect to the concentration of aqueous ammonia, and an apparent rate constant has been obtained as a function of catalyst concentration in solution, oxygen pressure, and reaction temperature.     

静电纺MnO2/PAN纳米纤维膜的制备及其催化氧化甲醛性能

通过液相沉积法制备MnO2,以PAN/MnO2/N,N-二甲基甲酰胺溶液作为纺丝液进行静电纺丝制备出MnO2/PAN纳米纤维膜。利用扫描电镜、透射电镜、傅里叶红外光谱、热重分析对纤维膜的结构和性能进行分析;并在甲醛废水体系中测试纤维膜催化氧化甲醛性能。结果表明：制备的纳米纤维其平均直径为196.46nm;随MnO2质量分数的增大和纺丝电压的增加,纤维平均直径均下降;pH值为2,温度60℃时,具有最佳甲醛催化氧化性能;纤维吸收12h后,对甲醛去除率达到44.0%;MnO2/PAN纤维膜比MnO2粉末具有更好的催化氧化甲醛性能。     

磷脂酶D的制备及催化磷脂酰胆碱合成磷脂酰丝氨酸

选用穗色链霉菌(Streptomyces racemochromogenes)作为磷脂酶D的生产菌株进行了酶的制备及条件优化,并在两相体系中进行了酶催化磷脂酰胆碱合成磷脂酰丝氨酸的研究。结果表明,最适的产酶条件为葡萄糖10 g/L、酵母粉5 g/L、鱼粉蛋白胨5 g/L、司班-60 10 g/L、氯化钙3 g/L,接种量1%、培养基初始p H 7.0、培养温度30℃,在最适产酶条件下酶活达到2 967 U/L,是优化前的2.12倍;最适的催化工艺条件为有机相二氯甲烷、反应温度35℃、p H 5.5、酶用量1.15 U/m L、钙离子浓度10 mmol/L,在该催化工艺条件下反应10 h后磷脂酰胆碱的生成率达94%。     

Monofluorinated analogues of polybrominated diphenyl ethers as analytical standards: synthesis, NMR, and GC-MS characterization and molecular orbital studies

Polybrominated diphenyl ethers (PBDEs), a group of 209 individual congeners distinguishable by the number and position of bromines, are produced for use as flame retardants in consumer goods. PBDEs have become ubiquitous environmental contaminants, present in increasing levels in the environment and humans. In the present study, 10 individual monofluorinated analogues of PBDEs (F-PBDEs) and one difluorinated PBDE (FF-PBDE) were synthesized and characterized, and their gas chromatographic (GC) and mass spectrometric (MS) characteristics determined. The synthesis method utilized a nucleophilic reaction of bromophenols with diphenyliodonium salts and the perbromination of fluorosubstituted diphenyl ethers. Reaction yields were between 10% and 59% with > or = 98% purity. Apart from the aromatic ring carrying the fluorine atom, only minor chemical nuclear magnetic resonance (NMR) shift changes were observed in comparison to the corresponding parent PBDEs, with the exception that the J(F,H) coupling was stronger. Our preliminary data show that F-PBDEs and PBDEs have comparable retention times in gas chromatography with F-PBDEs demonstrating in general shorter or identical retention times, depending on the pattern of fluorine substitution. We also calculated the torsion angles and the dipole moments for both and report that there is a good correlation between GC retention times and the torsion angles but not with dipole moments. In MS, the difference of the ion peaks of the F-PBDE/ PBDE pairs is m/z 19 (F), which allows a simultaneous MS detection without separation. On the basis of GC separation, simultaneous MS detection, and the stability of fluorine due to its generally resistance to nucleophilic displacement, we propose that F-PBDEs may function as valuable potential standards, markers, and tracers in environmental analysis.     

Pigment oxidation in ground veal: Influence of lipid oxidation, iron and zinc

The color stability of fresh ground veal from four different muscles (biceps femoris, longissimus dorsi, psoas major and supraspinatus) was characterized, and the effects of lipid oxidation, iron and zinc on this degradative process were investigated. Samples were minced and prepared in a manner consistent with retail production and analyzed for pH, myoglobin concentration, total and nonheme iron, and zinc. Pigment and lipid oxidation were measured on days 0, 3 and 6 of 4°C storage. B. femoris demonstrated the greatest extent of lipid oxidation, and was more color-labile than p. major or supraspinatus (P < 0·05), but no different from l. dorsi (P > 0·05). Total iron and myoglobin concentrations were lowest for l. dorsi (P<0·05). Zinc concentration in the four muscles followed the order supraspinatus ? b. femoris ? l. dorsi ? p. major (P < 0·05). Data analysis revealed that initial metmyoglobin formation (days 0 to 3) was significantly correlated with total iron (r = 0·69) or nonheme iron (r = 0·68) in b. femoris, but not any of the other muscles. Correlations between lipid and pigment oxidation in each of the four muscles were performed and the data support a strong relationship between these degradative processes in ground veal.     

双月桂酸三乙醇胺酯合成及性能研究

双月桂酸三乙醇胺酯是一类较好双子型表面活性剂,该研究反应条件对产物转化率影响,得出相对最佳反应条件为:以对甲苯磺酸作催化剂,反应温度140℃,月桂酸与三乙醇胺摩尔比2.1:1,催化剂用量为wt.2.5%,反应时间12 h,酯化率达86.95%。对该化合物性能测试,考察不同浓度盐酸溶液中囊泡现象、溶解能力、乳化能力、发泡能力等;研究结果表明:在pH值为2.1～2.4盐酸溶液中囊泡现象最好,该化合物表面活性低于一般表面活性剂,但持泡能力强,乳化能力好。     

一锅法合成氨基化纳米纤维素及其性能表征

为实现纳米纤维素衍生物的绿色高效制备,以过硫酸铵为氧化剂,基于机械力化学作用,在微波-水热条件下氧化降解竹浆粕得到羧基化纳米纤维素(CNC),然后与二乙烯三胺发生缩合反应,实现水相中氨基化纳米纤维素(ACNC)的一锅法合成,并对其性能进行研究。结果表明:ACNC呈棒状,直径为10~40 nm,长度为50~300 nm, 氨基的接枝率为6.29%;ACNC的晶型并未发生改变,仍为纤维素Ⅰ型,结晶度由竹浆粕的59%增加到79%;ACNC的热稳定性较竹浆粕并未显著下降,但较CNC显著提高,说明CNC表面接枝氨基后热稳定性能得到改善;该制备方法绿色高效,得到的纤维素衍生物有望在生物固化和物理性能增强方面发挥作用。     

Lipase-catalyzed synthesis and characterization of myristoyl maltose ester

Myristoyl maltose ester was synthesized by lipase-catalyzed reaction of maltose and myristic acid. Influence of different reaction parameters, such as molecular sieve concentration, molar ratio of acid/sugar, enzyme concentration, reaction time, and reaction temperature, was studied. Under the optimum conditions of 20 g/L molecular sieve, 14% (w/w) lipase from Novozym 435, and acid/sugar molar ratio of 5:1 at 60 °C for 60 h, the highest conversion (90%) was achieved. The as-prepared maltose ester was confirmed by Fourier-transform infrared spectra (FTIR), liquid chromatograph–mass spectrum (LC–MS), and scanning electron microscopy (SEM).     

Low temperature catalytic oxidation of hydrogen sulfide and methanethiol using wood and coal fly ash

The feasibility of reusing waste material as an inexpensive catalyst to remove sulfur compounds from gaseous waste streams has been demonstrated. Wood and coal fly ash were demonstrated to catalytically oxidize H2S and methanethiol (CH3SH) at low temperatures (23-25 degrees C). Wood ash had a significantly higher surface area compared to coal ash (44.9 vs 7.7 m2/g), resulting in a higher initial H2S removal rate (0.16 vs 0.018 mg/g/min) under similar conditions. Elemental sulfur was determined to be the end product of H2S oxidation, since X-ray diffraction analysis indicated the presence of crystalline sulfur. Catalytic decay occurred apparently due to surface deposition of sulfur and a subsequent decline in surface area (44.9-1.4 m2/g) during the reaction of H2S with the ash. Methanethiol was stoichiometrically converted to dimethyl disulfide ((CH3)2S2) without significant catalytic decay. Catalytic decay was reduced and H2S conversion increased (10% at 1.8 days vs 94% at 4.2 days) when H2S loading was decreased to levels typical of many environmental applications (500 ppmv inlet and 1.43 mg/min vs 60 ppmv, 0.09 mg/ min). Catalyst regeneration using hot water (85 degrees C) washing was possible, but only increased fractional conversion from 0.2 to 0.6 and the initial reaction rate to 50% of the original H2S oxidation activity.     

焙烧态水铝钙石催化剂的制备及催化合成生物柴油

分别采用共沉淀法、清洁法制备焙烧态水铝钙石,通过低温N2吸脱附法、CO2-TPD、XRD、DTA和FT-IR表征结构,并将其作为大豆油与甲醇酯交换合成生物柴油的催化剂,探讨制备方法对焙烧态水铝钙石催化合成生物柴油的影响。此外,考察了Ca/Al摩尔比、焙烧温度、甲醇与大豆油摩尔比(醇油比)、催化剂用量和反应时间对酯交换合成生物柴油的影响。结果表明,清洁法制备的焙烧态水铝钙石具有更高的比表面积,强碱中心的表面碱量更大,催化活性更高。当Ca/Al摩尔比为2∶1,焙烧温度为600℃时,制备的Ca2Al O-2-600催化剂的催化活性最高,在醇油比8∶1、催化剂用量3%、反应温度65℃、反应时间4 h的条件下,大豆油转化率达到98. 0%。催化剂经重复使用3次后仍保持较高催化活性。     

香料前体香叶醇-β-D-葡萄糖苷的合成、纯化与表征

为了开发热稳定型香原料,采用改进的Koenigs-knorr法立体选择性地合成了香叶醇-β-D-葡萄糖苷(Geranyl-β-D-Glycoside,GGLY);以反相液相色谱法(ReversePhaseHPLC,RP-HPLC)检测并确定最优反应条件;硅胶柱层析梯度洗脱分离制备样品,产物纯度达99.2%;然后综合IR、LC/MS/MS、1HNMR、13CNMR进行结构鉴定,确证制备的产物为香叶醇糖苷。     

Heterogeneous base catalytic transesterification synthesis of sucrose ester and parallel reaction control

The equilibrium solubility of sucrose in methyl stearate, methyl oleate and methyl laurate with or without the addition of surfactants was investigated. The side reactions, pyrolysis of the sucrose, glucose and fructose, are also discussed through studying their data of differential thermal analysis and thermal gravimetric analysis. Results show that the solubilities of sucrose in methyl esters of fatty acids range from 0.01 g/100 g to 0.21 g/100 g in a surfactant‐free system with the temperature range of 40–140 °C. The addition of surfactants increased the sucrose solubility in the fatty acid esters. Under the strict anhydrous conditions, the soap concentration can be controlled at a very low level. With the increase in the temperature, sucrose began to decrease in weight at 225 ± 5 °C, glucose began to decrease in weight at 85 ± 5 °C, and fructose began to decrease in weight at 170 ± 5 °C.