微波条件下固体酸催化剂催化酯化生物油的研究

以乙醇和乙酸的酯化作为反应模型,考察固体酸催化剂阳离子交换树脂、SO₄²-/ZrO₂和分子筛在微波加热条件下的酯化活性。结果表明,三类固体酸催化剂的活性顺序为Amberlite树脂﹥SO₄²-/ZrO₂﹥HZSM-5,催化剂活性与酸度一致;酯化反应中水的含量对催化剂的活性有不同程度的影响,水含量较高时催化剂SO₄²-/ZrO₂酯化活性明显变差,而阳离子交换树脂仍具有较高的酯化活性。采用阳离子交换树脂对生物油进行微波催化酯化提质后,原生物油中含有的大量不同种类的羧酸被有效地转化成各种酯类,酯类化合物由原油中的4种增加到13种。与传统加热条件下生物油催化提质比较,生物油微波提质具有明显优势,提质后生物油组分得到优化。     

Catalytic conversion of guaiacol to alcohols for bio-oil upgrading

Guaiacol was chosen to represent O-containing chemicals with lower effective hydrogen carbon ratio(H/Ceff factor) in bio-oil,and the hydrodeoxygenation of guaiacol was investigated over non-precious and nonsulfided catalysts. Effects of metal composition,reaction temperature,and hydrogen pressure on conversion and selectivity were investigated systematically. Among various compositions of catalysts,Ni Co/CNT exhibited best performance of guaiacol conversion with higher selectivity towards desired alcohols with higher H/Cefffactor. The reaction pathways of guaiacol in aqueous were proposed based on the product analyzed.Results show that metal composition and temperature have great effects on the conversion of guaiacol and the yields of desired products.     

固体酸改质生物油的研究

利用乙酸和乙醇生成乙酸乙酯的酯化反应为模型反应,筛选得到催化活性最好的固体酸催化剂40％SiO2/TiO2SO42－。 在一定的反应条件下,添加固体酸催化剂和溶剂,生物油的品质得到提高,热值提高了50.7％,运动黏度降低到原来的10％,密度降低了22.6％。生物油改质前后的GC MS分析表明,固体酸可以将生物油中含有的有机羧酸转化为酯类,如甲酸酯、乙酸酯等,使生物油中的羧酸组分发生了催化酯化反应,改善了生物油的品质,生物油物理化学性能得到明显的提高。3A分子筛对生物油的脱水作用不显著,对酸性、密度、黏度等方面影响较小。     

微波条件下ZnCl2改性离子交换树脂催化改质生物油的研究

在微波加热条件下,以732型阳离子交换树脂和ZnCl2改性离子交换树脂为催化剂,添加乙醇为溶剂,对生物油进行催化酯化改质.比较研究了两种催化剂随催化剂用量、反应时间及反应温度改变对生物油改质效果的影响,同时考察了微波加热与传统水浴加热条件下催化剂的活性.结果表明,酯化过程中ZnC12改性离子交换树脂比732型树脂活性有...     

Aqueous-phase catalytic hydrogenation of furfural to cyclopentanol over Cu-Mg-Al hydrotalcites derived catalysts: Model reaction for upgrading of bio-oil

A series of Cu-Mg-Al hydrotalcites derived oxides with a (Cu+Mg)/Al mole ratio of 3 and varied Cu/Mg mole ratio (from 0.07 to 0.30) were prepared by co-precipitation and calcination methods, then they were introduced to the hydrogenation of furfural in aqueous-phase. Effects of Cu/Mg mole ratio, reaction temperature, initial hydrogen pressure, reaction time and catalyst amount on the conversion rate of furfural as well as the selectivity toward desired product cyclopentanol were systematically investigated. The conversion of furfural over calcined hydrotalcite catalyst with a Cu/Mg mole ratio of 0.2 was up to 98.5% when the reaction was carried out under 140 °C and the initial hydrogen pressure of 4 MPa for 10 h, while the selectivity toward cyclopentanol was up to 94.8%. The catalysts were characterized by XRD and SEM. XRD diffraction of all the samples showed characteristic pattern of hydrotalcite with varied peak intensity as a result of different Cu content. The catalytic activity was improved gradually with the increase of Cu component in the hydrotalcite.     

Radical synthesis of tetrameric lignin model compound

The lack of suitable lignin model compound limits the understanding of the characteristics of lignin, and hence hinders the efficient utilization of this kind of bioresource. A tetramer phenolic lignin model compound composed of 5-5, α-O-4 and β-5 linkages was prepared by a two-step of free radical reaction with hydrogen peroxide/horseradish peroxidase and S₂O₈^2- /Fe²⁺ as the initiator. Compared with enzymatic process, this synthetic process gives a higher yield of 33.8% within a shorter time. HRMS and ¹³C NMR spectroscopy show that synthesized model compound contains phenylpropane structure linked by 5-5, α-O-4 and β-5 bonds, which can mimic some chemical characteristics of lignin.     

Steam reforming of toluene as model of tar compound over Mo catalysts derived from hydrotalcites

This study evaluated the catalytic activity of Mo catalysts derived from hydrotalcite-like compounds for steam reforming of toluene as a model compound for tar. The catalysts with 1.5, 3 and 4.5 Mo loadings (wt%), denoted as Mo_1.5MgAl, Mo₃MgAl and Mo_4.5MgAl respectively, were prepared by coprecipitation and characterized by BET, XRD, SEM, TEM, FT-IR and UV–VIS. The results showed that toluene conversion increased with increasing molybdenum content. The hydrogen amount depended on two factors: the presence of molybdate species on the surface and the presence of aluminum cations in tetrahedral sites (Mo₃MgAl), with molybdenum influence being more pronounced. The H₂/CO ratio decreased at increasing temperature while, the H₂/CO₂ ratio increased proportionally with temperature. Mo_1.5MgAl catalyst was more selective for CO₂ and H₂, while, Mo₃MgAl and Mo_4.5MgAl were more selective for CO and H₂.     

介孔分子筛反应精馏催化改性生物质裂解油

采用反应精馏的方法,以含锆介孔分子筛(S042-/Zr-MCM-41)为酸性催化剂,对生物质热解油进行了催化改性.通过XRD、N2吸附脱附及FT-IR表征了介孔分子筛的孔结构和表面基团.对生物油改性的较佳反应条件进行了考察,较佳的催化剂用量为生物油质量的4%,生物油、乙醇及过氧化氢水溶液(30%)的质量比为1:0.5:0.4,回流比1:6.在上述条件下,轻油收率21.4%(以生物油计).改性所得两种改性油与原料油相比,含水量由33%分别降至0.5%和5.0%,黏度由18.5 mm2/s分别降至0.46 mm2/s和3.65 mm2/s(30℃),pH值由2.82分别提升至7.06和5.35,热值由14.3 MJ/kg分别提升至21.5 MJ/kg和24.5 MJ/kg.经过GPC、Fr-IR和1H NMR分析,轻油主要成分是原料油中的轻组分所转化的酯类化合物,重油主要是原料油中难挥发的成分.     

Sol-gel derived oxides and mixed oxides catalysts with narrow mesoporous distribution

A novel sol-gel process for preparing oxides and mixed oxides sols from precipitation and peptization process is reported in this article. Inorganic salts are used as raw materials in this study. It is found that the amount of acid has great influence on the stability and particle diameter distribution of the precursor sols. Ultrasonic treatment is used to prepare alumina sol at room temperature. The result of 27AI NMR shows that there exist AI_13~(7+) species in the sol. By controlling the sol particles with narrow particle diameter distribution, alumina, titania and silica-alumina (SA) materials with narrow mesoporous distribution are formed by regular packing of sol particles during gelation without using any templates. The results also show that the structure and particle diameter distribution of precursor sol determine the final materials' texture.     

碱处理HZSM-5分子筛在线催化提质生物油

采用NaOH溶液对HZSM-5分子筛进行碱处理,利用XRD、SEM、BET、Py-FTIR四种方法表征改性HZSM-5分子筛,对生物原油有机相、未改性HZSM-5制得生物油有机相与改性HZSM-5制得生物油有机相进行理化特性及成分分析,研究了碱处理HZSM-5分子筛对生物油有机相产物的影响;对使用了120 min的三种失活催化剂进行了热重分析,并对焦炭峰面积进行了积分计算。结果表明,经过碱处理后的HZSM-5分子筛保留了典型的MFI拓扑结构,形成了一定数量的介孔;同时,经碱处理1 h的HZSM-5分子筛催化制得的生物油有机相产物的产率有所增加且理化特性得到提高,其产物中烃类物质的含量显著增加,达到了37.67%,且以单环芳香烃为主;同时改性HZSM-5分子筛对生物油有机相中的酸、醛及酮类物质均有较好的脱除效果,有效地降低了生物油的腐蚀性并提升了生物油的稳定性,热值达到了35.32 MJ/kg;经1 h碱处理的HZSM-5分子筛的总结焦量明显降低。     

Catalytic degradation of polystyrene using HUSY catalysts

Summary The addition of carbon dioxide to phenyl glycidyl ether (PGE) was investigated in a semi-batch reactor using immobilized quaternary ammonium chloride catalysts. Five different catalysts were prepared with the following supports : (1) soluble poly(ST-<Emphasis Type=Italic>co</Emphasis>-VBC) [C1], (2) insoluble poly(ST-DVB-VBC) [C2], (3) macroporous poly(ST-DVB-VBC) [C3], (4) poly(ST-<Emphasis Type=Italic>co</Emphasis>-VBC)-MMT [C4] (5) modified MCM-41 [C5]. The addition of carbon dioxide to PGE can be considered as a pseudo-first order process with respect to the concentration of PGE. The pseudo-first order rate constant for the catalysts decreased in the series C1&gt;C3&gt;C2&gt;C4&gt;C5. The activation energy for C1 to C5 catalysts was 8.6, 20.9, 19.9, 23.9, and 26.8 kJ/mol, respectively. The immobilized catalysts can be reused in least 4 successive runs without any considerable loss of their initial reactivities.     

Hydrogen production via steam reforming of bio-oil model compounds over supported nickel catalysts

The steam reforming of four bio-oil model compounds(acetic acid,ethanol,acetone and phenol) was investigated over Ni-based catalysts supported on Al2O3 modified by Mg,Ce or Co in this paper.The activation process can improve the catalytic activity with the change of high-valence Ni(Ni2O3,NiO) to low-valence Ni(Ni,NiO).Among these catalysts after activation,the Ce-Ni/Co catalyst showed the best catalytic activity for the steam reforming of all the four model compounds.After long-term experiment at 700°C and the S/C ratio of 9,the Ce-Ni/Co catalyst still maintained excellent stability for the steam reforming of the simulated bio-oil(mixed by the four compounds with the equal masses).With CaO calcinated from calcium acetate as CO2 sorbent,the catalytic steam reforming experiment combined with continuous in situ CO2 adsorption was performed.With the comparison of the case without the adding of CO2 sorbent,the hydrogen concentration was dramatically improved from 74.8% to 92.3%,with the CO2 concentration obviously decreased from 19.90% to 1.88%.     

生物油中固体颗粒物的特性分析

利用电感耦合等离子体发射光谱、红外光谱分析和X射线衍射对不同固体颗粒物样品的特性进行了研究。结果表明,生物油中的固体颗粒物主要由焦炭颗粒、灰分和少量高分子有机物组成,其中,灰分主要包括多种金属元素和一定量SiO₂,有机物主要是具有木质素结构的低聚物。不同热解工艺的固体颗粒物样品特性也不同。循环流化床工艺制取的生物油中固体颗粒物含量较高。此外,固体颗粒物样品中的金属元素含量受到热解原料种类的影响。     

芬顿预处理对木质素快速热解甲氧基脱除规律研究

采用不同H₂O₂含量的芬顿溶液对碱木质素进行预处理，并结合快速热解，探究轻质生物油中含甲氧基化合物含量的变化规律，同时研究了芬顿溶液对木质素结构的影响规律。结果表明，轻质生物油中含甲氧基团的酚类化合物峰面积从AL（未处理碱木质素）的7.3×10⁹下降至13-FML（H₂O₂含量为13 mL/g芬顿溶液预处理碱木质素）的5.2×10⁹，减少了0.29倍。而含甲基团和乙基团的酚类化合物峰面积从AL的3.9×10⁹上升到13-FML的7.2×10⁹，增加了0.85倍。同时，轻质生物油产率从22.4%提高到28.7%。通过FT-IR、¹H NMR和¹³C NMR分析发现，芬顿预处理使木质素凝缩性结构单元减少，甲氧基含量降低，为后续快速热解产生低甲氧基含量的生物油提供了有利条件。     

Component analysis of the fluorescence spectra of a lignin model compound

In order to test whether lignin fluorescence originates from discrete fluorophores, fluorescence emission spectra of the lignin model dehydrogenative polymer (DHP) were analyzed by the band deconvolution method and time-resolved analysis of both the excitation and emission spectra. Two series of 22 fluorescence emission spectra of DHP in chloroform/methanol (3:1, v/v) solution, and as a solid suspension in water, were deconvoluted into three fluorescence and one Raman Gaussian components. Emission spectra were obtained by stepwise variation of the excitation wavelength from 360 to 465 nm. Deconvolution was performed by nonlinear fitting of all three Gaussian parameters: area, width and position. Position of all components in a series was treated as a random variable and its approximate probability distribution (APD) calculated from a series of histograms with increasing number of abscissa intervals. A five peak multimodal APD profile was obtained for both series of DHP emission spectra. The mean fluorescence lifetime varied with wavelength both in the emission and the excitation decay-associated spectra (DAS), where four kinetic components were resolved. The shapes of the excitation spectra of the four components were quite different and gradually shifted bathochromically. The multicomponent nature of the DHP emission spectra along with the changes in the mean fluorescence lifetime and the form of the excitation DAS of the four components give evidence of the heterogeneous origin of fluorescent species emitting in the visible.     

Catalytic enantioselective sulfinyl transfer using cinchona alkaloid catalysts

[reaction: see text] Practical reaction conditions for the catalytic enantioselective synthesis of sulfinate esters are reported. Commercially available cinchona alkaloids were found to be superior catalysts for the sulfinyl transfer reaction of tert-butanesulfinyl chloride and a variety of benzyl alcohols. Sulfinyl transfer with 2,4,6-trichlorobenzyl alcohol and 10 mol % of the commercially available, inexpensive catalyst quinidine provided the pure sulfinate ester product in 92% isolated yield and with 90% ee.     

木质素二聚体模型化合物热解机理的量子化学研究

β-O-4连接是木质素主体结构单元之间的主要联结方式。采用密度泛函理论方法B3LYP,在6-31G (d, p)基组水平上,对β-O-4型木质素二聚体模型化合物(1-愈创木基-2-(2-甲氧基苯氧基)-1,3丙二醇)的热解反应机理进行了研究。提出了三种热解反应途径:C_β-O键均裂的后续反应、C_α-C_β键均裂的后续反应以及协同反应。对各种反应的反应物、产物、中间体和过渡态的结构进行了能量梯度全优化,计算了各热解反应途径的标准动力学参数。分析了各种主要热解产物的形成演化机理以及热解过程中温度对热解机理的影响。计算结果表明,C_β-O键的均裂反应和协同反应路径(1)和(3)是木质素二聚体热解过程中主要的反应路径,而C_α-C_β键的均裂反应和协同反应路径(2)和(5)是主要的竞争反应路径;热解的主要产物是酚类化合物如愈创木酚、1-愈创木基-3-羟基丙酮、3-愈创木基-3-羟基丙醛、愈创木基甲醛和乙烯等。在热解低温阶段协同反应是热解过程中的主要反应形式,而在高温阶段自由基均裂反应是热解过程的主要反应形式。     

Catalytic dehydration of ethanol using transition metal oxide catalysts

The aim of this work is to study catalytic ethanol dehydration using different prepared catalysts, which include Fe(2)O(3), Mn(2)O(3), and calcined physical mixtures of both ferric and manganese oxides with alumina and/or silica gel. The physicochemical properties of these catalysts were investigated via X-ray powder diffraction (XRD), acidity measurement, and nitrogen adsorption-desorption at -196 degrees C. The catalytic activities of such catalysts were tested through conversion of ethanol at 200-500 degrees C using a catalytic flow system operated under atmospheric pressure. The results obtained indicated that the dehydration reaction on the catalyst relies on surface acidity, whereas the ethylene production selectivity depends on the catalyst chemical constituents.     

Catalytic oxidation of ethylene using functional quinone-polymer-anchored palladium catalysts

Organic quinone polymers containing sulphonic acid functional groups, combined with palladium ion, gave heterogeneous oxidation catalysts which are effective for the selective oxidation of ethylene to acetaldehyde. Two forms of the resins, soluble or insoluble in water, were made by use of differ- ent networks of cross-linked polymers. Both polymer-anchored palladium catalysts showed stable activities for the ethylene oxidation without any co-catalyst such as CuCl₂. The rates and reaction kinetics to form acetaldehyde were determined. The effect of the combination of Pd(II) with polyquinone on the catalytic reaction, and a comparison of the anchored catalysts with a homogeneous catalyst PdCl₂-CuCl₂ are discussed.