超临界醇类提质生物油的研究进展

综述了超临界醇类提质生物油的研究进展。介绍了反应条件对超临界醇类提质生物油的影响,通过分析酸、醛、酮、酚4种生物油中不稳定组分所发生的反应,探讨了生物油提质中主要的反应机理,总结了催化剂的种类。最后对超临界醇类提质生物油的研究方向进行了展望。     

Pt/C催化生物油加氢制备含氧液体燃料

生物油是很有发展前景的第二代生物燃料,但生物油成分极其复杂,是一种不稳定的混合物,经过改性后才可成为能实际应用的液体燃料。催化加氢是改性的重要方法之一,文章采用Pt/C催化剂两步法加氢提质生物油,得到饱和醇类液体燃料。第一步加氢采用温和的条件(80℃,2 h,2 MPa H2,800 rpm,5 wt.%Pt/C),目的在于饱和醛基和部分碳碳双键,得到稳定油;第二步加氢在260℃、270℃和280℃三个温度的条件(3 h,4 MPa H2,800 rpm,5 wt.%Pt/C)下,分别得到了75.89%、85.38%和80.36%的醇含量,加氢效果明显。     

木质素在超临界甲醇和乙醇溶剂中液化过程分析

通过研究木质素分别在超临界甲醇和乙醇溶剂中的液化过程，分析反应温度（260～340℃）及反应时间（0～120min）对木质素在两种溶剂中的转化率、生物油收率及其组分差异的影响。实验表明，木质素在超临界乙醇中的转化率及产物收率均高于甲醇。当反应温度340℃，反应时间60min，木质素在超临界乙醇中的转化率和生物油收率比在甲醇中分别提高了16.23%和11.54%，残渣收率降低了16.23%。通过GC-MS和FTIR对生物油和残渣分析，发现生物油组分中芳香族化合物相对含量较高，在甲醇和乙醇溶剂中分别达到66.13%和58.84%；随着反应时间的延长，甲醇溶剂中残渣的醚键官能团逐渐增强，而在乙醇溶剂中则先增强后减弱。分析认为在木质素降解过程中，超临界乙醇和甲醇均可产生氢自由基作为供氢体，攻击木质素及其大分子片段中的官能团，同时使液化产物中的活性片段减活，减弱重聚合反应，从而更利于芳烃产物的生成。而甲醇在液化过程中容易与木质素断键产生的苯酚中间体发生脱氢缩合反应，通过醚键聚合产生长链芳香族化合物，形成残渣，降低生物油收率。     

超临界乙醇体系中苯酚催化加氢的降解规律

目前,液化的生物油与石油粗油成分接近,通常环类化合物含量高,如煤焦油中酚及其衍生物含量占40%以上,急需加氢升级技术。超临界乙醇（243.1℃,6.38MPa）温度、压力条件低,具有良好的传质性能,且为绿色、可再生溶剂。在超临界乙醇体系下的催化加氢是一种油升级有效方式。本文以苯酚为生物油中环类化合物典型模型,在300～400℃、Pt/C催化剂下,探讨超临界乙醇体系下苯酚催化加氢过程。研究分析了超临界乙醇中温度、氢气压力和反应时间对苯酚催化加氢降解规律的影响,并建立了能很好地描述过程中苯酚转化率的动力学模型（R2 = 0.989）。实验表明：该体系下的苯酚催化加氢降解反应的级数为二级,反应的活化能为51.7kJ/mol;尽管升高温度和氢气压力均能提高苯酚的转化率,但温度对转化率的影响更为显著。本研究将为更好地控制反应过程和提高超临界乙醇体系中苯酚的转化率提供参考。     

微藻粗生物油催化加氢提质：外加氢源影响

催化加氢是微藻粗生物油改性提质的有效途径,其中氢源是关键。探究了5种常规金属(铁、铝、锡、锌、镁)在超临界水条件下的产氢量,相同质量下铝的产氢量最大。在400℃、2 h条件下,以Ru/C为催化剂,以四氢萘为供氢介质对比了4种不同氢源(即微藻水热液化水溶物水热气化氢-M-HTL-H₂、小球藻水热气化氢-M-SCW-H₂、单质金属铝与水高温反应氢-Al-H₂及实验室氢-L-H₂)对微藻水热液化所得粗生物油的加氢提质效果。结果表明,无论何种氢源,提质产物中提质油产率最高,其中L-H₂所得提质油产率最高(87.6%),而M-SCW-H₂所得提质油产率最低(70.4%)。4种氢源对粗生物油具有不同的加氢提质效果,其中Al-H₂对生物油的脱氧效果最好(93.03%),同时提质油热值最高(43.05 MJ/kg);M-SCW-H₂的脱氮效果最好(86.11%);4种氢源对生物油的脱硫效果均达到90%以上。氢源对提质油成分组成影...     

胜利褐煤超临界乙醇脱氧实验研究

为有效脱除褐煤中含氧官能团,采用超临界乙醇工艺处理胜利褐煤,研究温度、停留时间和醇煤质量比对胜利褐煤脱氧效果的影响,并利用FT-IR和GC/MS对固液相产物进行表征。结果表明,胜利褐煤超临界乙醇脱氧的最佳工艺条件为:温度270℃,停留时间90 min,醇煤质量比5∶1,此时煤样总氧含量为9.29%,脱氧率为61.40%,固相产率为89.62%。在220℃得到的液相产物中,80%左右为芳香族类化合物,酚类和酯类含氧化合物体积分数低于5%,其他含氧类化合物11.29%。270℃得到的液相产率中芳香族类化合物体积分数降低31.69%,含氧类化合物体积分数增加2.81%,酚类和酯类含氧化合物增至35%左右。褐煤经超临界醇解后,乙醇与煤分子作用发生了醚氧桥键的断裂反应,煤分子发生了脱羧反应,液相产物中含有大量酚类(主要为苯酚及其取代物)和酯类(主要为乙酯类)。     

超临界乙醇技术原理研究与运用进展

综述了超临界乙醇在制备生物柴油中的主要技术,分析了在酯交换反应、酯化反应、液化反应制生物油以及生物油加氢升级中的原理及应用。研究表明,超临界乙醇的酯交换反应过程由三个连续可逆的反应组成,水和CO_2均能提高反应速率。在酯化过程中,乙醇、酸的浓度对过程存在显著影响,此外,动力学模型表明酸存在催化效应,因此水解及油酸本身存在酸催化效应及自催化作用。超临界乙醇被广泛用于生物质的液化过程,过程主要存在:(1)生物质裂解;(2)油份重整(涉及酯交换及酯化反应等);(3)结焦或结聚;(4)小分子组分气化;及(5)气体间相互反应等典型反应等;且升高温度有利于液化;液化过程中醇与水表现出协同作用。此外,在生物油的加氢升级过程中,超临界乙醇不仅作为一种良好的反应介质,也作为反应物与生物油中的酸类物质发生酯化反应,降低生物油的酸度,提高生物油的热值。因此,超临界乙醇在生物燃料的制备与升级中具有良好的应用前景。     

生物油电催化加氢提质技术研究进展

生物油是一种可再生的碳中和有机资源,在液体燃料和高值化学品生产中显示出较大的潜力,对其大规模利用有助于实现碳中和目标。生物油因其固有的腐蚀性和化学不稳定性而需要提质以提高其应用价值。电催化加氢能够在常温常压下实现生物油加氢提质,该方法反应条件温和、操作简单、能源效率高,具有碳中和属性,为生物油提质提供了新的选择。综述了近年来生物油电催化加氢的研究进展,分析了不同生物油模型化合物在电催化加氢过程中的作用机理。讨论了真实生物油样品的电催化加氢实例,以证明电催化应用于生物油提质的可行性。最后,针对生物油电催化加氢提质技术面临的困难和挑战,提出了该领域未来的研究方向和重点,并展望了生物油电催化加氢提质工业化应用的前景。     

浅谈催化加氢脱氧法从木质素到芳烃衍生物

从木质素出发制备芳烃及其衍生物,是一条不依赖石油资源制备芳烃的技术路线。然而由木质素制备得到的生物油中含有大量的含氧化合物,包括酚、醚、酮、醛、醇、酸和酯等。由于大量含氧基团的存在,虽然燃烧时不会给环境带来污染,但油品品质显著降低,如低热值、化学不稳定性、粘度大和对设备腐蚀等,严重阻碍了其作为汽柴油替代燃料的广泛应用,必须对其进行脱氧精制。催化加氢脱氧(HDO)因具有绿色化的化学反应,较高的原子经济性,被认为是一种行之有效的针对生物油进行脱氧精致的方法。但由于木质素衍生物中酚羟基、醚键中的氧与苯环直接相连,断裂此类C-O键所需的活化能较高,难以脱除,催化加氢脱氧技术难度被认为大于加氢脱硫和加氢脱氮。因而,开发一种高效加氢脱氧催化剂就显得尤为重要了。经过大量的实验与尝试,我们发现耐水铌酸催化剂是可以用于未来工业化生产的突破方向之一。     

生物质焦油改性提质制取燃料油的研究进展

介绍了生物质焦油改性提质制取燃料油的研究进展,对催化裂解、乳化调和、加氢脱氧、水蒸气重整和超临界流体提质等常见的生物油改性提质技术进行了总结。基于生物质焦油和煤焦油的异同点,提出将两者混合在超临界汽油条件下加氢裂解,制高品位燃料油的思路。通过生物质焦油改性提质,将其与煤焦油共同深加工或加氢转化,在解决生物质焦油加工工艺的同时,一定程度上可以使煤焦油的加工转化变得绿色环保。     

Upgrading of bio-oil in supercritical ethanol: Catalysts screening,solvent recovery and catalyst stability study

Supercritical upgrading of bio-oil is an effective method to upgrade bio-oil. In this paper, upgrading of bio-oil was carried out in supercritical ethanol with the aim of catalyst selection, reducing solvent consumption and catalyst stability study. Compared with Ru/HZSM-5, C-supported catalysts (Pt/C, Pd/C, and Ru/C) gave better catalytic performance. Over the C-supported catalysts, the heating value increased from 21.45 MJ/kg to about 30 MJ/kg and the pH value increased from 3.13 to about 5.5. The relative content of desired products reached as high as 80% over Ru/C. The ratio of ethanol to bio-oil was further reduced to about 1:1 by solvent recovery and reutilization. The relative content of desired products particularly that of esters increased with the recovered solvent. Catalytic stability study of Ru/C showed that the relative content of desired products decreased gradually with the number of catalyst recycle times while the consumption of hydrogen decreased mainly in the first recycle. Coke deposition and sintering of metal particles were the main reasons for the deactivation of Ru/C.     

双循环反应系统中麦饭石催化提质生物质热解挥发分

以麦饭石作为催化提质床料,在双循环反应系统中进行了生物质快速热解挥发分的催化提质实验,考察了麦饭石提质床料、催化提质温度和提质循环速率对生物质快速热解产物的影响。和石英砂相比,麦饭石催化提质降低了焦油产率,但提高了焦油中轻质焦油的相对含量。同时,麦饭石促使生物油中的氧元素以H₂O、CO和CO₂的形式脱除,且主要以H₂O和CO的形式脱除,使焦油中烃类、酚类含量显著增大,酸类、酮类物质含量显著降低。催化提质温度升高更有利于焦油中的氧以H₂O和CO形式脱除,焦油中烃类相对含量随提质温度升高而增加,而酸、酯、酮类含量降低。提高催化提质循环速率,焦油中轻质组分相对含量增加,但焦油中烃类、酚类相对含量均降低。在提质温度520℃,提质循环速率5.5kg/h时,提质油品质较好,轻质焦油含量较高,酚类物质相对含量可达到46.37%。     

Production of renewable fuels by blending bio-oil with alcohols and upgrading under supercritical conditions

The work studied a non-catalytic upgrading of fast pyrolysis bio-oil by blending under supercritical conditions using methanol, ethanol and isopropanol as solvent and hydrogen donor. Characterisation of the bio-oil and the upgraded bio-oils was carried out including moisture content, elemental content, pH, heating value, gas chromatography-mass spectrometry (GCMS), Fourier transform infrared radiation, ¹³C nuclear magnetic resonance spectroscopy, and thermogravimetric analysis to evaluate the effects of blending and supercritical reactions. The GCMS analysis indicated that the supercritical methanol reaction removed the acids in the bio-oil consequently the pH increased from 2.39 in the crude bio-oil to 4.04 after the supercritical methanol reaction. The ester contents increased by 87.49% after the supercritical methanol reaction indicating ester formation could be the major deacidification mechanism for reducing the acidity of the bio-oil and improving its pH value. Simply blending crude bio-oil with isopropanol was effective in increasing the C and H content, reducing the O content and increasing the heating value to 27.55 from 17.51 MJ·kg^‒1 in the crude bio-oil. After the supercritical isopropanol reaction, the heating value of the liquid product slightly further increased to 28.85 MJ·kg^‒1.     

厨余垃圾水热液化制取生物燃料

以厨余垃圾为原料进行水热液化,考察了反应温度和料液比对产物分布的影响。温度320℃、料液比1:15时,生物油产率最高为16.7%,继续升高温度或降低料液比将促进气体产物生成。与重质原油、常减压渣油相比,生物油氧、氮元素含量较高,热值为32.33~34.82 MJ·kg^-1,其中汽油和煤柴油馏分超过50%。利用GC-MS、FT-IR和FT-ICR MS对生物油化学组成、官能团和杂原子组成进行了表征。生物油是一种复杂混合物体系,已检测出烃类、酸类、醛类、酮类、酯类、胺类、酚类、醇类和含氮杂环类等多种物质,对其酸性组分进一步分析显示,含氧组分主要是O₂、O₃类化合物,含氮组分主要是N₁O₂、N₁O₃和N₁O₄类化合物。     

番泻叶药渣超临界甲醇解产物的 GC／MS 分析

采用GC/MS分析解聚产物,研究了番泻叶药渣在超临界甲醇条件下的解聚产物。结果表明：番泻叶药渣超临界甲醇解聚产物所含成分复杂。 GC/MS分析鉴定出了58种化合物,化合物类型主要有酯类、酮类、醇类、烯烃类、酚类、含氮类及其它类化合物,其中大部分是甲酯类化合物,共27种,相对百分含量为59.43％;第二大类的是酮类化合物,相对含量为15.07％,首次鉴定出羽扇烯酮,相对含量达11.31％。甲醇参与了番泻叶药渣甲醇超临界解聚反应,同时存在酯化反应和超临界萃取作用,番泻叶药渣的超临界解聚反应的机理有待更深入的研究。该研究结果为番泻叶药渣的进一步利用提供了科学依据。     

鸡肉及其酶解液挥发性风味成分的对比分析

为了研究酶解对鸡肉挥发性风味成分的影响,采用SPME法提取鸡肉及其酶解液中的挥发性风味成分,用气相色谱-质谱联用技术进行分离鉴定。结果显示:鸡肉酶解液共鉴定出63种挥发性风味成分,包括醛类19种、醇类7种、酸类2种、酮类6种、酯类2种、醚类2种、酚类3种、烃类8种、杂环化合物14种。水煮鸡肉的挥发性风味成分共19种,包括醛类11种、醇类3种、酮类1种、酯类1种、烃类2种、杂环化合物1种。两者共同鉴定出的物质有:己醛、辛醛、壬醛、(E)-2-辛烯醛、苯甲醛、苯乙醛、(E,E)-2,4-癸二烯醛、对甲氧基苯甲醛、1-辛烯-3-醇、右旋萜二烯。     

A review on catalytic & non-catalytic bio-oil upgrading in supercritical fluids

This review article summarizes the key published research on the topic of bio-oil upgrading using catalytic and non-catalytic supercritical fluid(SCF)conditions.The precious metal catalysts Pd,Ru and Pt on various supports are frequently chosen for catalytic bio-oil upgrading in SCFs.This is reportedly due to their favourable catalytic activity during the process including hydrotreating,hydrocracking,and esterification,which leads to improvements in liquid yield,heating value,and pH of the upgraded bio-oil.Due to the costs associated with precious metal catalysts,some researchers have opted for non-precious metal catalysts such as acidic HZSM-5 which can promote esterification in supercritical ethanol.On the other hand,SCFs have been effectively used to upgrade crude bio-oil without a catalyst.Supercritical methanol,ethanol,and water are most commonly used and demonstrate catalyst like activities such as facilitating esterification reactions and reducing solid yield by alcoholysis and hydrolysis,respectively.     

Comparison of three accelerated aging procedures to assess bio-oil stability

The current study utilizes three stability ranking methods to compare oxidative and thermal stability of alcohol-stabilized and un-stabilized slow pyrolysis bio-oil. Procedures were based on standard methods established by ASTM (D5304 and E2009) for hydrocarbon fuels and on a widely used method that assesses viscosity change over time. Each method involves an accelerated aging procedure ranging from several minutes to 24 h. Average stability rankings for bio-oils produced from two biomass feedstock (pine and peanut hull) in two pyrolysis units were compared. Bio-oils in order from most to least stable included; methanol-stabilized pine pellet oil, un-stabilized pine pellet oil, ethanol spray-condensed pine pellet oil, methanol-stabilized peanut hull oil, and un-stabilized peanut hull pellet oil. FT-IR spectra from pre- and post-aging showed an increase in the relative concentration of C-O (phenols, carboxylic acids, esters, and ethers) and CO (carbonyl) functional groups for aged samples.     

Physicochemical criteria for reverse osmosis separation of aldehydes,ketones, ethers,esters, and amines in aqueous solutions using porous cellulose acetate membranes

Reverse osmosis separation of 62 different proton acceptor compounds (bases) including 7 aldehydes, 8 ketones, 12 ethers, 11 esters, and 24 amines in aqueous solutions in the concentration range 0.00075 to 0.003 g mole/l. (～100 ppm in most cases) have been studied using porous cellulose acetate membranes at 250 psig. All reverse osmosis data are for single solute systems. Solute separation data for aldehydes, ketones, ethers, and esters are correlated with Δv_s (basicity) (shift in the OD band maximum in the IR spectra of CH₃OD in benzene and other solvents used as solutes in reverse osmosis experiments), and those for the amines are correlated with dissociation constant (given as pK_a) and the degree of dissociation of the molecule. Solute separation increases with increase in Δv_s (basicity) for aldehydes, ketones, ethers, and esters and with increase in degree of dissociation for amines. The separation data and the basicity parameters for the above classes of compounds are also correlated with Taft numbers. The results are consistent with those reported earlier for alcohols, phenols, and monocarboxylic acids in aqueous solutions and show that data on Δv_s (basicity), pK_a, and Taft numbers are valid physicochemical criteria governing reverse osmosis separation of aldehydes, ketones, ethers, esters, and amines.     

采用多相放电反应技术加氢精制生物油的试验研究

针对目前生物油加氢技术中存在的催化剂易结焦、工艺过程不能连续等问题,采用多相放电反应对生物油进行加氢精制。构建了生物油/固体催化剂/H₂的多相放电体系,研究了催化剂类型、工作电压、气体流量、反应时间等条件对精制生物油的加氢脱氧效果的影响。研究结果表明：随着工作电压和气体流量的增大,多相放电催化加氢精制生物油的脱氧率（R）呈现出先增加后减少的趋势;随着反应时间的延长,呈现出先增加后稳定的趋势。在工作电压为22kV,气体流量为60mL/min,反应时间为120min的工艺条件下,脱氧率最高可达41%。与生物原油相比,多相放电催化加氢精制的生物油中醇类、酚类、酮类等物质的含量相对较低,而碳氢类物质显著增多。