非均相羰基氧化一步合成碳酸二苯酯的研究(Ⅴ)筛选催化剂及优化合成条件

Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated that the catalyst Pd/LaxPbyMnOz had higher activity. The Pd/LaxPbyMnOz catalyst and the support was characterized by XRD, SEM and TEM, the main phase was Lao.szPbo.asMnOa and the average diameter could be about 25.4nm. The optimuna conditions for synthesis of DPC with Pd/LasPbyMnOz were determined by orthogonal experiments and the experimental results showed that reaction temperature was the first factor of effect on the selectivity and yield of DPC, and the concentration of O2 in gas phase also had significant effect on selectivity of DPC. The optimum reaction conditions were catalyst/phenol mass ratio l to 50, pressure 4.5MPa, volume concentration of O2 25%, reaction temperature 60℃ and reaction time 4 h. The maximum yield and average selectivity could reach 13% and 97% respectively in the     

单过氧丁二酸氧化环己酮合成ε-己内酯(英文)

In the absence of catalyst, 70% hydrogen peroxide was used to oxidize succinic anhydride to solid monoperoxysuccinic acid（PSA）. Then PSA was applied to synthesis of ε-caprolactone（ε-CL） by oxidation of cyclohexanone in the heterogeneous system. In order to achieve material recycle, solid precipitated in the process of synthesizing ε-CL was dehydrated via reactive distillation followed by recrystallization to prepare succinic anhydride, which was characterized by IR（infrared spectra） and1HNMR（1H nuclear magnetic resonance）. Effects of molar ratio of PSA to cyclohexanone, acetic acid dosage, reaction temperature, reaction time on conversion of cyclohexanone, yield and selectivity of ε-CL were investigated respectively. The results indicated that conversion of cyclohexanone, yield and selectivity of ε-CL were upto 98.1%, 97.5% and 99.4% respectively under the optimal conditions. In addition, in the process of synthesizing succinic anhydride, the optimal yield of succinic anhydride reached 67.4%.     

反应条件对钌催化剂和铁催化剂的氨合成性能影响

Activated carbon-supported Ru-based catalyst and A301 iron catalyst were prepared,and the influences of reaction temperature,space velocity,pressure,and H2/N2 ratio on performance of iron catalyst coupled with Ru catalyst in series for ammonia synthesis were investigated.The activity tests were also performed on the single Ru and Fe catalysts as comparison.Results showed that the activity of the Ru catalyst for ammonia synthesis was higher than that of the iron catalyst by 33.5%-37.6% under the reaction conditions:375-400 °C,10 MPa,10000 h-1,H2︰N2 3,and the Ru catalyst also had better thermal stability when treated at 475 °C for 20 h.The outlet ammonia concentration using Fe-Ru catalyst was increased by 45.6%-63.5% than that of the single-iron catalyst at low tem-perature (375-400 °C),and the outlet ammonia concentration increased with increasing Ru catalyst loading.     

液相合成甲醇催化剂活性的研究

The effects of reduction procedure, reaction temperature and composition of feed gas on the activity of a CuO-ZnO-Al2O3 catalyst for liquid phase methanol synthesis were studied. An optimized procedure different from conventional ones was developed to obtain higher activity and better stability of the catalyst. Both CO and CO2 in the feed gas were found to be necessary to maintain the activity of catalyst in the synthesis process. Reaction temperature was limited up to 523K, otherwise the catalyst will be deactivated rapidly. Experimental results show that the catalyst deactivation is caused by sintering and fouling, and the effects of CO and CO2 on the catalyst activity are also investigated. The experimental results indicate that the formation of water in the methanol synthesis is negligible when the feed gas contains both CO and CO2. The mechanism for liquid-phase methanol synthesis was discussed and it differed slightly from that for gas-phase synthesis.     

Influences of operating conditions on biocatalytic activity and reusability of Novozym 435 for esterification of free fatty acids with short-chain alcohols:A case study of palm fatty acid distillate

In the present study, the effects of operating conditions on biocatalytic activity and stability of Novozym 435 for repeated-batch biodiesel production from free fatty acid (FFA) were investigated. Thermal deactivation caused by increased operating temperature from 45 to 50 °C could seriously affect the reusability of Novozym 435. The deactivation of Novozym 435 during the esterification of oleic acid with ethanol tended to be stronger than that in the system with methanol. Under the optimal conditions, considering both biocatalytic activity and stability of the enzyme, Novozym 435 could be reused for 13 cycles for biodiesel productions from oleic acid and absolute alcohols (methanol and ethanol) with FFA conversions of at least 90%. The presence of 4%–5%water in ethanol significantly affected the reusability of Novozym 435. Changes in the surface morphology of Novozym 435 during the esterification with various conditions were observed. It was revealed that the reduc-tion in catalytic activity was related to the swel ing degree of the catalyst surface. Additionally, biodiesel produc-tion from low cost renewable feedstocks, such as palm fatty acid distillate (PFAD) and 95%ethanol was examined. The esterification of PFAD with 95%ethanol catalyzed by Novozym 435 in 10-repeated batch operation showed the similar results in FFA conversion as compared to those using oleic acid. Novozym 435 remained active and could maintain 97.6%of its initial conversion after being used for 10 batches.     

固体超强酸催化剂SO2-4/TiO2-MoO3的制备及其催化合成缩醛（酮）

SO4^2-/TiO2-MoO3, a novel solid superacid, has been prepared and its catalytic activity at different synthetic conditions was examined with esterification of n-butanoic acid and n-butyl alcohol as probing reaction.The optimum conditions were also found, that is, the mass ratio of MoO3 used in the compound is 25%, the calcination temperature 450℃, and the soaked consistency of H2SO4 is 0.5mol.L^-1. Then it was applied in the catalytic synthesis of six similar important ketals and acetals as catalyst and revealed high catalytic activity. Under the condition that the molar ratio of aldehyde/ketone to glycol was 1:1.5, the mass ratio of the catalyst to the reactants was 0.5% and the reaction time 1.0 h, the yield of ketals and acetals reached up to 63.2%. The catalyst can be easily recovered and reused.     

Catalytic kinetics of dimethyl ether one-step synthesis over CeO_2–CaO–Pd/HZSM-5 catalyst in sulfur-containing syngas process

CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg~(-1)·h~(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.     

Synthesis and catalytic activity of SBA-15 supported catalysts for styrene oxidation

Cu(II) and Mn(II) metals embedded on mesoporous SBA-15 were synthesized by co-precipitation technique.The support and catalysts were characterized by SEM–EDX,TEM,BET,XRD and ICP-AES methods.The catalytic activity of these catalysts was evaluated for styrene oxidation at various reaction conditions such as styrene to TBHP mole ratio,temperature,catalyst amount by using TBHP as an oxidizing agent.Major reaction products were styrene oxide and benzaldehyde and highest styrene conversion(97.3%) was observed at styrene to TBHP mole ratio of 1:4,temperature at 80 °C and 20 mg of catalyst.Further,the recyclability of the catalysts was observed and found that they can be recycled three times without major loss in their activity and selectivity.     

晶格氧用于轻烃的选择氧化

In this paper, selective oxidation of n-butane to maleic anhydride (MA) and partial oxidation of methane to synthesis gas with lattice oxygen instead of molecular oxygen are investigated. For the oxidation of butane to MA in the absence of molecular oxygen, the Ce-Fe promoted VPO catalyst has more available lattice oxygen and provides higher conversion and selectivity than that of the unpromoted one. It is supposed that the introduction of Ce-Fe complex oxides improves redox performance of VPO catalyst and increases the activity of lattice oxygen.For partial oxidation of methane to synthesis gas over LaFeO3 and Lao.8Sro.gFeO3 oxides, the reaction with flow switched between 11% O2-Ar and 11% CH4-He at 900℃ was carried out. The results show that methane can be oxidized to CO and H2 with selectivity over 93% by the lattice oxygen of the catalyst in an appropriate reaction condition, while the lost lattice oxygen can be supplemented by air re-oxidation. It is viable for the lattice oxygen of the LaFeO3 and La0.8Sr0.2FeO3 catalyst instead of molecular oxygen to react with methane to synthesis gas in the redox mode.     

A safe and efficient process for the preparation of difluoromethane in continuous flow

Difluoromethane is typically produced vialiquid-phase fluorination as performed in a batch reactor. However,this process suffers from some problems, e.g., severe corrosion of the reactor, high safety risk, and the regeneration of the catalyst. In this paper, a flow process as performed in the tubular reactor was designed. The optimum conditions for continuous synthesis of difluoromethane were obtained as follows: the reaction temperature was 100℃, the molar ratio of dichloromethane to hydrogen fluoride was 1.6:1 and the reaction time was 300 s. The operation of the cyclic process was stable for 24 h with the conversion per pass of hydrogen fluoride up to 16.2%.The unreacted raw materials were easily reused. The deactivation of the common catalyst, antimony pentachloride, was investigated by catalyst concentration curve and XPS analysis. The approach proposed in this work is proven to be safe, efficient and low amount of catalyst.     

维生素E琥珀酸酯的酶促合成及优化

在有机溶剂中以维生素E和琥珀酸酐为底物在脂肪酶的催化下合成了维生素E琥珀酸酯。首先对酶促反应的脂肪酶、反应介质和反应温度进行了考察,在所选的几种脂肪酶中,假丝酵母脂肪酶(Candidasp.)的催化活性最好;叔丁醇和DMSO组成的混合溶剂(体积比为2∶3)为最合适的反应介质;30℃为适宜的反应温度。并采用Box-Behnken实验设计和响应面因子分析法对底物摩尔比等其他反应条件进行了优化。维生素E琥珀酸酯最优反应条件为:维生素E浓度0.26mmol.ml-1,维生素E和琥珀酸酐摩尔比1∶5,在5ml叔丁醇和DMSO混合溶剂(体积比为2∶3)中,30℃下在0.02gCandidasp.脂肪酶的催化下反应71h,维生素E琥珀酸酯产率达到98.71%。     

维生素E琥珀酸酯的合成及其稳定性研究

以4-二甲氨基吡啶为催化剂,以维生素E和琥珀酸酐为原料合成维生素E琥珀酸酯.采用正交设计法对工艺进行优化,并采用HPLC法对产品进行了分析.研究了原料配比、催化剂用量、溶媒用量、反应温度、反应时间等因素对产率的影响及维生素E琥珀酸酯在不同贮藏条件下的稳定性.结果表明,在优化的条件下,维生素E琥珀酸酯的平均产率达88.57%;维生素E琥珀酸酯对光和热均不稳定,应在低温、避光条件下制备和保存.     

酶催化合成高分子量聚丁二酸丁二醇酯(PBS)及其材料特性

建立了以固定化南极假丝酵母脂肪酶B(Novozym-435)作为催化剂,以丁二酸二乙酯和1,4-丁二醇作为原料,酶催化合成聚丁二酸丁二醇酯(PBS)的工艺。在95℃,真空条件下经过25 h反应,得到重均分子量44000的PBS,分子量分布为1.64。通过红外光谱、核磁共振、元素分析等分析了合成PBS的组成及分子结构。对酶催化聚合反应过程的动力学,以及反应过程中固定化酶的热稳定性进行了研究。通过对PBS材料性能的表征,证明其具有良好的耐热性能、力学性能和生物降解性能。     

Enzymatic synthesis of poly(ε-caprolactone): thermal properties, recovery, and reuse of lipase B from Candida antarctica immobilized on macroporous acrylic resin particles

Candida is a genus of yeast, and lipase B isolated from Candida antarctica (CALB) has been utilized as a biocatalyst for the synthesis of a variety of organic compounds including polyesters and polylactones. Among the various immobilization media reported in the literature, the porous acrylic resin utilized in Novozym-435 has been widely studied. Here, we report the enzyme recovery and reuse for the synthesis of poly(ε-caprolactone) in toluene at 70 °C for 4 h per cycle for up to 10 reaction cycles, which consistently resulted in polymers with a weight-average molecular weight, M _w , of ~50,000 g mol^?1 and a polydispersity index of ~1.4. In addition, the thermal properties of the resin particles used in Novozym-435, with and without the enzyme, were evaluated by TGA and DSC analysis. The effect of mechanical agitation on the enzyme stability, recovery, and reuse was also discussed. These results may have significance to enzymatic polymer synthesis as well as to the enzyme immobilization on acrylic resins and other matrices.     

脂肪酶N435在低沸点溶剂中催化合成聚丁二酸丁二醇酯

脂肪酶N435在温和条件下可以有效地催化合成聚丁二酸丁二醇酯.采用溶剂蒸出的多级酶催化法成功在低沸点溶剂正己烷、四氢呋喃、甲苯和乙腈中合成出聚丁二酸丁二醇酯,得到聚丁二酸丁二醇酯的重均分子量分别为1460、1636、3066和4231,多分散系数分别为1.69、1.48、1.78和1.67.低沸点溶剂甲苯和乙腈是N43...     

高取代度酯化淀粉的制备与工艺研究

采用有机溶剂法制备高取代度淀粉琥珀酸酯。以琥珀酸酐为酯化剂,对淀粉进行酯化改性。经单因素试验法得到淀粉琥珀酸酯的制备条件,采用正交试验法研究淀粉琥珀酸酯制备的最佳工艺条件：反应温度50℃,反应时间5 h,每克活化淀粉催化剂用量1 m L,活化淀粉与酸酐分子的摩尔比为1∶3。在最佳制备条件下,制得取代度为0.40的淀粉琥珀酸酯。     

Synthesis of biodiesel from edible and non-edible oils in supercritical alcohols and enzymatic synthesis in supercritical carbon dioxide

Biodiesel is an attractive alternative fuel because it is environmentally friendly and can be synthesized from edible and non-edible oils. The synthesis of biodiesel from edible oils like palm oil and groundnut oil and from crude non-edible oils like Pongamia pinnata and Jatropha curcas was investigated in supercritical methanol and ethanol without using any catalyst from 200 to 400 °C at 200 bar. The variables affecting the conversion during transesterification, such as molar ratio of alcohol to oil, temperature and time were investigated in supercritical methanol and ethanol. Biodiesel was also synthesized enzymatically with Novozym-435 lipase in presence of supercritical carbon dioxide. The effect of reaction variables such as temperature, molar ratio, enzyme loading and kinetics of the reaction was investigated for enzymatic synthesis in supercritical carbon dioxide. Very high conversions (>80%) were obtained within 10 min and nearly complete conversions were obtained at within 40 min for the synthesis of biodiesel in supercritical alcohols. However, conversions of only 60–70% were obtained in the enzymatic synthesis even after 8 h.     

Synthesis and characterization of biodegradable poly(1,4-butanediol succinate)

Biodegradable poly(1,4-butanediol succinate) was synthesized from 1,4-butanediol and succinic anhydride. The synthesized polymer was identified by ¹H-NMR spectrometer and FT-IR spectrophotometer. The weight average molecular weights were between 4,600 and 29,000, and molecular weight distributions were in the range of 1.7 and 1.9. The glass transition temperature of poly(1,4-butanediol succinate) was revealed at 73°C. The crystallization and cold crystallization of the polymers were investigated as a function of heating rate, cooling rate, reheating rate, and molecular weight. The biodegradation behavior of poly(1,4-butanediol succinate) in micro-organisms such as fungi, actinomycetes, and bacteria was studied by using modified ASTM method. Based upon visual observation, the crystalline structure of films composed of larger molecular weight polymers retained their crystallinity longer than similar structures in low molecular weight samples. © 1995 John Wiley & Sons, Inc.     

The STOBBE condensation. X. The cyclisation of (E)-3-methoxycarbonyl-4-(5′-methyl-2′-furyl)-but-3-enoic acid,and (E)−3-methoxycarbonyl-4-(2′-furyl)-pent-3-enoic acid,to Benzofuran Derivatives

The condensation of 5-methyl-furan-2-aldehyde and 2-furyl-methyl ketone with dimethyl succinate using either potassium t-butoxide or sodium hydride as condensing agents, gives predominantly (E)-3-methoxycarbonyl-4-(5′-methyl-2′-furyl)-but-3-enoic acid 1a and (E)-3-methoxy-carbonyl-4-(2′furyl)-pent-3-enoic acid 5 respectively. Their configurations are inferred by cyclisation with sodium acetate in acetic anhydride to the corresponding benzofuran derivatives 2,6 . Alcoholysis of (E)-3-carboxy-4-(5′-methyl-2′-furyl)-but-3-enoic anhydride 3 gives the half-ester 1c which is isomeric with the half-ester 1a . A competing side reaction also gives the self-condensation product of the succinic ester 4 .     

金属负载型阳离子树脂催化合成琥珀酸单乙酯

采用金属负载型阳离子交换树脂作催化剂,乙醇和丁二酸酐为原料,对琥珀酸单乙酯的合成进行了研究,确定了最佳工艺条件：原料摩尔比n（乙醇）,n（丁二酸酐）=1．3：1,催化剂用量占丁二酸酐用量的15％。反应温度85℃,反应时间90min,乙酸正丁酯的产率达到93％以上。