反胶束漆酶/纤维素酶体系中油酸酯化的优化

漆酶和纤维素酶在反胶束水核中心具有较强的催化活性。为了对反胶束酶体系中油酸酯化反应深入研究,采用生物表面活性剂鼠李糖脂构建反胶束体系作为漆酶与纤维素酶酯化油酸的催化反应场所。通过实验研究了反胶束体系的不同条件对酯化产物含量的影响。对于反胶束漆酶体系,最佳酯化条件为:含水量W040%,鼠李糖脂临界胶束浓度20mmol·L^(-1),pH值4,温度40℃;对于反胶束纤维素酶体系,最佳酯化条件为:含水量20%,鼠李糖脂临界胶束浓度80 mmol·L^(-1),pH值4,温度30℃。综合考虑几个因素,漆酶比纤维素酶更适合应用于反胶束中油酸的酯化。研究同时采用荧光光谱法对漆酶和纤维素酶在反胶束体系中结构性能的变化进行研究,结果表明,当反胶束体系处于最佳酯化反应条件时,荧光强度最高。

SBA-15铌改性的研究

用直接合成和后合成法以及直接合成后草酸处理三种方法制备了铌改性催化剂Nb-SBA-15。采用XRD,BET,FT-1R,DTA方法对样品进行表征。结果表明,直接合成的(Z)-Nb-SBA-15与后合成的(H)-Nb-SBA-15结构不同。以合成油酸异丙酯为探针反应,对不同方法制备的催化剂及直接合成经草酸处理后催化剂的催化性能进行评价,结果表明:(H)Nb SBA 15的活性羟基多,催化活性高,但稳定性差;(Z)-Nb-SBA-15的活性羟基少,催化活性低,但稳定性较好;(Z)-Nb-SBA-15经草酸改性后的催化活性及稳定性均较好。

Green and efficient epoxidation of methyl oleate over hierarchical TS-1

The epoxidation of methyl oleate(MO)was conducted in the presence of aqueous H2O2 as the oxidant and hierarchical TS-1(HTS-1)as the catalyst;the catalyst was synthesized using polyquaternium-6 as the mesopore template.The effects of various parameters,i.e.,H2O2/C=C molar ratio,oxidant concentration,amount of the catalyst,reaction temperature,and time,were systematically studied.Furthermore,response surface methodology(RSM)was used to optimize the conditions to maximize the yield of epoxy MO and to evaluate the significance and interplay of the factors affecting the epoxy MO production.The H2O2/C=C molar ratio and catalyst amount were the determining factors for MO epoxidation,wherein the maximum yield of epoxy MO reached 94.9%over HTS-1 under the optimal conditions.

The Kinetics of the Esterification of Free Fatty Acids in Waste Cook- ing Oil Using Fe2（SO4）3/C Catalyst

The esterification of free fatty acids(FFA) in waste cooking oil with methanol in the presence of Fe2(SO4)3/C(ferric sulfate/active carbon) catalyst was studied.The effects of different temperature,methanol/FFA mole ratio and amount of catalyst on the conversion of FFA were investigated.The results demonstrated that under optimal esterification conditions the final acid value of the resultant system can be reduced to ～1(mg KOH)·g-1,which met fully the requirements in post-treatment for efficient separation of glycerin and biodiesel.The kinetics of the esterification were also investigated under different temperatures.The results indicated that the rate-control step could be attributed to the surface reaction and the esterification processes can be well-depicted by the as-calculated kinetic formula in the range of the experimental conditions.

Modified graphene‐based materials as effective catalysts for transesterification of rapeseed oil to biodiesel fuel

Production of biodiesel by the transesterification process using different modified graphene‐based materials as catalysts was studied.Solid acid graphene‐based samples were prepared by grafting sulfonic or phosphate groups on the surface of thermally reduced graphene oxide.The obtained materials were thoroughly characterized using scanning electron microscopy,X‐ray diffraction,thermogravimetric analysis,X‐ray photoelectron spectroscopy,N2 adsorption‐desorption measurements,potentiometric titration,elemental analysis,and Fourier transform infrared spectroscopy.The prepared catalysts were tested in the transesterification of rapeseed oil with methanol at 130°C under pressure,and their activities were compared to the performance of a commercially available heterogeneous acidic catalyst,Amberlyst‐15.All modified samples were active in the transesterification process;however,significant differences were observed in the yield of biodiesel,depending on the method of catalyst preparation and strength of the acidic sites.The highest yield of fatty acid methyl esters of 70%was obtained for thermally reduced graphene oxide functionalized with 4‐benzenediazonium sulfonate after 6 h of processing,and this result was much higher than that obtained for the commercial catalyst Amberlyst‐15.The results of the reusability test were also promising.

Fat and Oil Oxidation by Electron Spin Resonance （ESR） Spin-Trapping Method

Oxidation of fats and oils during storage causes their degradation and loss of nutritional value and appearance. Electron spin resonance （ESR） is the only method that can be used to directly observe the radicals. In this study, the authors used an ESR spin-trapping method to study the oxidation of triacylglycerols （TAG） containing different fatty acids （FAs） commonly found in food. The ESR adduct signals were analyzed to study the effect of double bonds and the chain length of the FAs of TAG on oxidation. Oxidation was conducted by applying UV irradiation to TAG by dissolving it in N-tert-buthyl〈t-phenylnitrone （PBN）, which trapped the radicals induced in the TAG as an ESR adduct signal. The detection was clearly successful. There were no differences in the spectra of tristearin （18：0） and tripalmitin （16：0）; thus, it can be concluded that the length of the carbon chain of the FAs of TAG does not affect the oxidation reactions. However, the ESR spectra of tristearin （18：0）, triolein （18：1） and trilinolein （18：3） were clearly different due to the presence/absence of a new peak corresponding to new induced radicals, leading to the conclusion that double bonds play a major role in the oxidation reactions of fats and oils.

Optimization of conjugated linoleic acid triglycerides via enzymatic esterification in no-solvent system

We compared four esterifiable enzymes. The lipase Novozym 435 possessed the highest activity for the conjugated linoleic acid esterification during the synthesis of triglycerides. The triglycerides were synthesized by esterification of glycerol and conjugated linoleic acid （CLA） in a no-solvent system using lipase catalysis. We investigated the effects of temperature, enzyme concentration, water content, and time on esterification. Enzyme and water concentrations of up to 1% of the total reaction volume and a system temperature of 60℃ proved optimal for esterification. Similarly, when the esterification was carried out for 24 h, the reaction ratio improved to 94.11%. The esterification rate of the rotating screen basket remained high （87.28%） when the enzyme was re-used for the 5th time. We evaluated the substrate selectivity of lipase （NOVO 435） and determined that this lipase prefers the 10,12-octadacadienoic acid to the 9,11-octadecadienoic acid.

A Novel Scheduling Strategy for Crude Oil Blending

For those refineries which have to deal with different types of crude oil, blending is an attractive solution to obtain a quality feedstock. In this paper, a novel scheduling strategy is proposed for a practical crude oil blending process. The objective is to keep the property of feedstock, mainly described by the true boiling point (TBP) data, consistent and suitable. Firstly, the mathematical model is established. Then, a heuristically initialized hybrid iterative (HIHI) algorithm based on a two-level optimization structure, in which tabu search (TS) and differential evolution (DE) are used for upper-level and lower-level optimization, respectively, is proposed to get the model solution. Finally, the effectiveness and efficiency of the scheduling strategy is validated via real data from a certain refinery.

Optimization of Wax Esters Production from Palm Fatty Acid Distillate and Oleyl Alcohol over Amberlyst 15

Wax esters were derived from long chain fatty acids and long chain alcohols with chain length of 12 carbons or more. These compounds have many potential applications in cosmetics, pharmaceuticals and food industries. The present work focuses on the synthesis of wax esters using palm fatty acid distillate and oleyl alcohol catalyzed by Amberlyst 15. Response surface methodology （RSM） based on a five-level, three-variable central composite design （CCD） was used to evaluate the interactive effects of synthesis, of amount of Amberlyst 15 catalyst （21.6-38.4% w/w）, reaction time （18-102 min） and molar ratio （palm fatty acid distillate to oleyl alcohol, 1：1.16-1：2.84） on the percentage conversion of palm fatty acid distillate. The optimum conditions derived via RSM were： amount of catalyst 33% w/w, reaction time 95 minute and palm fatty acid to oleyl alcohol molar ratio 1：2.7. The actual experimental conversion was 81.52% under optimum condition, which compared well to the maximum predicted value of 80.50%. Analysis of the yield showed that at optimum condition, 80.54% wax esters were produced.

Separation of arenols from a high-temperature coal tar

A high-temperature coal tar collected from Xuzhou Coking Plant, Saint-Gobain Pipelines （Xuzhou） Co., Ltd. was exhaustively extracted with petroleum ether （PE）. The extract was sequentially eluted through silica gel with PE and PE/ethyl acetate （EA） mixed solvents （volume ratio 2：1 ） to afford two eluted frac- tions. The extract and eluted fractions were analyzed with gas chromatography/mass spectrometry. In total, 14 arenols were detected, including phenol, cresols, xylenols, fluorenols, phenanthren-3-ol and pyren-l-ol.

Modification of methyl oleate for silicon-based biological lubricating base oil

A new kind of silicon-based biological lubricating base oil with good viscosity-temperature behavior,viscosity index,thermostability,oxidation stability and wear resistance performance was synthesized as a derivative of methyl oleate.Trimethylsilylation reaction was introduced to further improve methyl oleate oxidation stability and lubricity after epoxidation and open-ring reactions.The order of effectiveness of acid binding agent was N,N-diisopropylethylamine(DIEA) > pyridine > diethylamine > triethylamine,and the effects of various parameters on the trimethylsilylation reaction as well as on the silicon-oxygen bond stability and reaction yield were studied.A maximum yield of 34.54%was achieved at hydroxyl/trimethyl chlorosilane/DIEA molar ratio of1:1.25:1,reaction temperature 40℃,reaction time 1.5 h.

Role of cyclooxygenase-2 in lipid metabolism in hepatic stellate cells

Hepatic stellate cells(HSCs) are a kind of adipocytes. In HSCs lipids mainly exist in the form of lipid droplets. They are abundantly found in the cytoplasm and their main constituents are triglycerides. Lipid metabolism in HSCs is closely related to its biological activity, however the mechanism of lipid droplets disappearance after HSC activation is not clearly established yet. Recent research shows that, cyclooxygenase-2 plays an important regulatory role in the lipid metabolism of HSCs. This paper seeks to review the subject based on studies that have been conducted so far to understand the role of cyclooxygenase-2 in the metabolism of lipids in HSCs.

Esterification of Free Fatty Acids in Waste Cooking Oil by Heterogeneous Catalysts

Waste cooking oil(WCO) is becoming the most promising alternative feedstock to produce biodiesel due to its low cost in China. In this study, NKC-9 ion-exchange resin and H-beta zeolite were selected as heterogeneous catalysts in the WCO esterification process and their esterification characteristics were compared by orthogonal experiments. NKC-9 resin showed higher activity and achieved a higher final conversion compared with H-beta zeolite under the same reaction conditions. Reusability experiments showed that NKC-9 resin still exhibited high activity after 5 runs. The effects of the mole ratio of alcohol to oil, reaction time, reaction temperature and the catalyst dose were investigated by multifactor orthogonal analysis. The influence of the free fatty acid(FFA) content was also investigated, and the result showed that the esterification rate could be as high as 98.4% when the FFA content was 6.3wt%.

An efficient catalytic system for the synthesis of glycerol carbonate by oxidative carbonylation of glycerol

Glycerol carbonate was synthesized by the oxidative carbonylation of glycerol catalyzed by the commercial Pd/C with the aid of NaI. High conversion of glycerol （82.2%）, selectivity to glycerol carbonate （〉99%）, and TOF （900 h-1） were obtained under the conditions of 5 MPa （Pco：Po2 = 2：1）, 140 C, 2 h. The highly active palladium species were generated in situ by dissolution from the carbon support and stabilized by re-deposition onto the support surface after the reaction was finished. Palladium dissolution and re-deposition were crucial and inherent parts of the catalytic cycle, which involved heterogeneous reactions. This Pd/C catalyst could be recycled and efficiently reused for four times with a gradual decrease in activity. Moreover, the in- fluences of various parameters, e.g., types of catalysts, solvents, additives, reaction temperature, pressure, and time on the conversion of glycerol were investigated. A reaction mechanism was proposed for oxidative carbonylation of glycerol to glyc- erol carbonate.

Transesterification of glyceryl tributyrate with methanol using strontium borate as the solid base catalyst

Four kinds of strontium borates were prepared and characterized by XRD, SEM, EDS, TG-DTA and Hammett titration method and their catalytic activities were examined in the transesterification of glyceryl tributyrate with methanol for the first time. The separate effects of the molar ratio of methanol to oil, the reaction time, and reusability were investigated. In addition, the catalytic activities of Sr（OH）2 and SrCO3 were also examined for the comparison. The results showed that the basicity and catalytic activity of these catalysts were decreased as the following order： Sr（OH）2 〉 SrB2O4·4H2O 〉 SrB6O10·5H2O 〉 SrB2O4 〉 SrB6O10 〉 SrCO3, and the reusability decreases as the following order： anhydrous strontium borates （SrBgO4, SrB6O10） 〉 hydrated strontium borates （SrB2O4·4H2O, SrB6O10·5H2O） 〉 Sr（OH）〉 The results indicate that the SrB2O4·4H2O with regular morphology, which was obtained at low temperature by a simple preparation method, might be as one kind of good potential alkaline earth salts catalyst for transesterification. Moreover, the possible reaction mechanism is proposed and analyzed.

Ordered mesoporous Ba CO_3/C-catalyzed synthesis of glycerol carbonate from glycerol and dimethyl carbonate

Ordered mesoporous BaCO3/C composites were synthesized by a multi-component co-assembly method combined with a carbonization process using phenolic resol as carbon source, barium nitrate as barium precursor, and triblock copolymer Pluronic F127 as template. The synthesized materials were characterized by X-ray diffraction, transmission electron microscopy, N2 physical adsorption, thermogravimetric analysis, and temperature-programmed desorption of CO〉 When BaCO3 contents were increased from 9.1 wt% to 44.7 wt%, pore size increased from 3.1 to 4.3 nm and the BET （Brunauer-Emmett-Teller） surface area initially increased to a maximum value of 390 m2 g^-1 （at a BaCO3 content of 18.5 wt%） before subsequently decreasing. BaCO3 was well dispersed in the amorphous carbon framework, and no phase separation was observed. The mesoporous BaCO3/C composites exhibited high catalytic activities toward the transesterification of glycerol and dimethyl carbonate into glycerol carbonate. A glycerol conversion of 97.8% and a glycerol carbonate selectivity of 98.5% were obtained under the optimized reaction conditions.