亚超临界水中蓝藻的热化学液化

分别考察了反应温度、反应时间和反应物料液比对蓝藻在亚超临界水中的热化学液化效果的影响,结果表明,在反应温度为380℃,反应时间为40 min,反应物料液比为1:20时,液化效果最好,总转化率和油产率分别达到94.5％和41.3％.生物油的GCMS、元素和热值分析表明,生物油的主要成分是芳香族、吡咯和吡啶衍生物等物质,生...     

纤维素亚临界和超临界水液化实验研究

在温度为340～420℃、压力为30～40MPa的实验条件下，对亚临界和超临界水中纤维素液化进行实验研究，液化产物经GC—MS分析，得到其主要成分是糠醛、5-甲基糠醛、5-羟甲基糠醛和一些含甲基、羟基、羟甲基等官能团的酮类、苯酚类化合物，且反应温度变化时，液化产物成分和浓度有较大变化；对纤维素液化转化率有重要影响的两个因素——反应温度和纤维素与水质量比进行初步实验研究，结果表明：(1)反应温度为380℃左右。液化转化率最高；(2)纤维素与水的质量比为1：15左右，转化率达最大值。     

杜氏盐藻在亚/超临界水中液化制生物油

在高温高压反应釜中进行亚/超临界水直接液化杜氏盐藻制生物油过程的研究。对杜氏盐藻的藻粉和藻渣两种原料的主要成分进行了分析。考察了反应温度、反应时间、催化剂、料液比、反应压力等对盐藻粉和盐藻渣液化行为的影响。在此基础上通过正交试验表明:反应温度360℃,反应时间60min,催化剂K_2CO_3加入量2.5%是适合的条件。在上述条件下微藻在超临界水中的液化率为89.37%,产油率为29.04%。通过FT-IR、GC-MS等手段分析了生物油的特性和组分,表明生物油是组成复杂的酸性有机混合物。     

微藻热化学催化液化及生物油特性研究

以杜氏盐藻为原料,乙二醇为液化介质、浓硫酸为催化剂进行热化学液化反应.运用中心组合设计及响应面分析(RSA),在单因素试验的基础上建立了预测杜氏盐藻液化产率的数学模型.回归分析表明,液化温度、停留时间与催化剂用量及其交互作用对液化都有显著影响.以液化产率为响应值作响应面和等高线图,揭示了各参数交互关系.通过响应面优化,求得最佳工艺条件为:催化剂用量2.4%,液化温度170℃,停留时间33min,在此条件下液化率达到97.05%.基于生物油广泛应用的目的,对产物生物油的物理化学性质进行了研究,并结合FT-IR、~(13)C-NMR、GC-MS等技术对生物油的主要组分分布进行了分析.结果表明:生物油的主要成分为苯并呋喃酮30.43%、C14～C18有机酸甲酯23.25%和C14～C18有机酸羟乙基酯27.89%.生物油由于高的含氧量,需要进一步改性才能高端应用.     

利用微藻热化学液化制备生物油的研究进展

微藻是制备生物质液体燃料的良好材料,利用微藻热化学液化制备生物油在环保和能源供应方向都具有非常重要的意义。目前国内外研究者主要采用快速热解液化和直接液化两种热化学转化技术进行以微藻为原料制备生物油的研究。快速热解生产过程在常压下进行,工艺简单、成本低、反应迅速、燃料油收率高、装置容易大型化,是目前最具开发潜力的生物质液化技术之一。但快速热解需要对原料进行干燥和粉碎等预处理,微藻含水率极高,会消耗大量的能量,使快速热解技术在以微藻为原料制备生物油方面受到限制。直接液化技术反应温度较快速热解低,原料无需烘干和粉碎等高耗能预处理过程,且能产生更优质的生物油,将会是微藻热化学液化制备生物油发展的主流方向,极具工业化前景。国内外研究者还尝试利用超临界液化、共液化、热化学催化液化、微波裂解液化等多种新型液化工艺进行微藻热化学液化制备生物油的实验研究。今后的主要研究方向应是将热化学液化原理研究、生产工艺开发、反应器研发、反应条件优化、产品精制等有机地结合起来,进行深入研究。同时应努力节约成本、降低能耗。     

污泥直接液化制取生物质油试验研究

采用热化学直接液化技术处理污泥,考察了试验过程中温度、催化剂和反应停留时间3个因素对反应的影响,成功获取生物质油,并对反应产物进行分析。结果表明,温度控制在250℃、采用催化剂N且停留70 min时,可获取较高生物质油产量,产油率达25.4%。同时,处理后固体残渣体积仅为原料污泥的10%,不含寄生虫、病毒等有害微生物。该处理方法为污泥资源化、减量化、无害化处理提供了一个新途径。     

亚临界乙醇条件下的纤维素热化学液化研究

以甘油为液化促进剂,在酸性催化剂条件下对微晶纤维素的亚临界液化工艺进行考察。实验结果表明:浓硫酸是较好的酸性催化剂,在微晶纤维素、浓硫酸、甘油和乙醇的质量比为1∶0.025∶2.5∶5,反应温度250℃,反应时间1h的条件下,转化率可达95.7%。对液化产物的理化性能进行分析,粘度509.3mm2/s、酸值2.51mgKOH/g和羟值784.6mgKOH/g。通过红外光谱(IR)、GC-MS、1H NMR等技术手段对产物进行分析表征。结果表明,产物含有丰富的羟基基团,粘度适宜,适用于聚氨酯发泡体系。对液化机理进行探讨。     

木屑复合溶剂液化及液化油的组分分离试验研究

以浓H2SO4为催化剂,采用甘油-甲醇复合溶剂体系,利用高温高压下甲醇的超/亚临界效应,探索了原料粒径、液化时间对杂木屑液化效果的影响。研究结果表明:在1 L的高压釜内,甲醇300 g,甘油150 g,浓硫酸1.5 g,粒径为0.28~0.90 mm的杂木屑60 g,在250℃下反应10 min,然后通冷却水快速冷却,木屑转化率为88.87%。利用精馏分离方法对液化油进行分级分类,分别收集70℃以下,70~80℃,80~90℃三个温度段的馏分,进行精馏试验的物料衡算,并通过GC-MS分析各馏分的物质构成,结果表明,各馏分的物质构成较复杂,但主要是一些小分子含氧衍生物,包括烃类、醇类、醛类、酯类、酮类以及芳香族等类别化合物。通过液化油与其精馏釜残留对比分析结果发现,两者在官能团构成、分子量分布上区别不大,说明液化油稳定性较好,在精馏过程中并未发生过多的聚合反应。     

生物质直接催化液化的研究

采用离子交换法制备Mn,Ni金属改性分子筛催化剂,用扫描电镜(SEM)和X射线衍射(XRD)对催化剂的性质进行表征,并将此催化剂应用在大豆秸秆直接液化反应中。通过对无催化剂和不同催化剂作用下得到的液体燃油的元素分析和GC-MS分析,结果表明,改性分子筛催化剂对生物质的直接液化有明显的催化作用,尤其是Mn/ZSM-5。以Mn/ZSM-5分子筛为催化剂能将生物油的产率从10.65%提高到14.61%,增加芳烃和烷烃的相对含量至12.78%和22.31%,将生物油的氧含量降低至6.28%,而生物油的热值则提高到43.56 MJ/kg。此法为通过催化剂调控生物油的组成和相对含量提升生物燃油的品质提供了研究基础。     

稻草在离子液体([Emim]Br)中的热解研究

为研究离子液体对植物纤维素热解行为的影响,以稻草为原料,在离子液体溴化3-甲基-1-乙基咪唑([Emim]Br)中进行热解反应,考察了反应温度、离子液体与稻草的质量比及反应时间对生物油产率的影响,得到热解较佳工艺条件:热解反应温度为230℃,离子液体与稻草的质量比为2∶1,热解反应时间为45 min,生物油得率达到38.1%。对热解得到的生物油进行GC-MS分析,呋喃类和苯酚类物质的含量较高,分别占17.17%和21.98%。     

Thermochemical liquefaction characteristics of Cyanobacteria in subcritical and supercritical ethanol–water mixture

The thermochemical liquefaction of Cyanobacteria in subcritical and supercritical ethanol–water mixture was studied with different reaction temperature, reaction time, solvent composition, and solid–liquid ratio. Highest bio‐oil yield of 42.5% containing mainly fatty acid ethyl esters, phenols, pyrrolidinones, and pyridinols was obtained in ethanol–water mixture (4/6, v/v) at temperature of 320°C for 30 min, with solid–liquid ratio of 1 g/15 mL. Both solvent composition and supercritical state had great influence on the liquefaction of Cyanobacteria, while the synergetic effects of water and ethanol in co‐solvents were again verified. Copyright © 2017 John Wiley & Sons, Ltd.     

生物质的热化学反应特性和秸秆气化问题

能量利用是生物质工业利用的主要途径。以热化学为基础的生物质气化、液化转换技术，提高了生物质的能量密度和能量强度，提升了其利用品位。如技术路线得当，这些转换产物可取代部分常规能源。生长期仅1年的作物秸秆属于高挥发分、低炭化度的物料，其木质素含量为12％，纤维素含量为75％。秸秆受热后在很宽的温度范围内(105～550℃)可转化为气态挥发物，这些物质遇热则燃烧释放能量，遇冷则凝结为焦油及水污。有效利用秸秆等生物质废弃物是一个值得深入研究的问题。     

Comparative studies of thermochemical liquefaction characteristics of microalgae using different organic solvents

The effect of different organic solvents, such as methanol, ethanol and 1,4-dioxane, on thermochemical liquefaction characteristics of Spirulina (a kind of high-protein microalgae) was systematically studied. The liquefaction experiments were conducted in a 1000 mL autoclave at different temperatures from 573 to 653 K with a fixed solid/liquid ratio. Liquefaction of Spirulina processed in methanol and ethanol favored the conversion rate and bio-oil yield compared with that in 1,4-dioxane solvent. The bio-oil generated in methanol contained higher C and H concentrations but a lower O content, resulting in a higher caloric value (39.83 MJ/kg). The results of FT-IR (Fourier Transform Infrared Spectroscopy) and GC-MS (Gas Chromatography-Mass Spectroscopy) analyses indicated that the compositions of bio-oil products were greatly affected by the type of solvent used for the liquefaction process. The major component of bio-oil produced with methanol was hexadecanoic acid methyl ester (C₁₇H₃₄O₂, 35.53%). However, ethanol favored the formation of hexadecanoic acid ethyl ester (C₁₈H₃₆O₂, 26.27%). When Spirulina were operated with 1,4-dioxane, the bio-oil was dominated by hexadecanenitrile (C₁₆H₃₁N, 22.7%). The presence of methanol and ethanol might promote the formation of esters. Low-boiling-points compounds with phenol ring structure or heterocyclics can be generated when 1,4-dioxane was employed as solvent.     

Supercritical liquefaction of common reed (Phragmites australis) with alkali catalysts

Milled Phragmites australis was liquefied in organic solvents with and without catalyst in a cylindrical reactor at temperatures of 533, 553, and 573 K under supercritical conditions. The liquefied compounds were extracted with diethyl ether and benzene using an extraction procedure. The product yields without catalyst in supercritical methanol, ethanol, and acetone were found to be 55.4%, 64.4%, and 73.5% at 573 K respectively. The highest conversion to liquid products was obtained in supercritical acetone with 10% sodium hydroxide as catalyst at the same temperature in the catalytic runs. Main chemical compounds present in the liquid products obtained in ethanol without catalyst and acetone with sodium hydroxide catalyst at 573 K were analyzed and characterized by gas chromatography–mass spectrometry (GC-MS).     

Hydrothermal liquefaction of spent coffee grounds in water medium for bio-oil production

Spent coffee grounds (SCG) were liquefied in hot-compressed water to produce crude bio-oil via hydrothermal liquefaction (HTL) in a 100 cm³ stainless-steel autoclave reactor in N₂ atmosphere. We investigated the effects of operating parameters such as retention times (5 min, 10 min, 15 min, 20 min and 25 min), reaction temperatures (200 °C, 225 °C, 250 °C, 275 °C and 300 °C), and water/feedstock mass ratios (5:1, 10:1, 15:1 and 20:1) and initial pressure of process gas (2.0 MPa and 0.5 MPa) on the yield and properties of the resulting crude bio-oil. The highest yield of the crude bio-oil (47.3% mass fraction) was obtained at conditions of 275 °C, 10 min retention time and water/feedstock mass ratio of 20:1 with an initial pressure of 2.0 MPa. The elemental analysis of the produced crude bio-oil revealed that the oil product had a higher heating value (HHV) of 31.0 MJ kg⁻¹, much higher than that of the raw material (20.2 MJ kg⁻¹). GC–MS and FT-IR measurements showed that the main volatile compounds in the crude bio-oil were long chain aliphatic acids and esters.     

Hydrothermal catalytic liquefaction mechanisms of agal biomass to bio-oil

The liquefaction mechanisms of the algal biomass to bio-oil were investigated by using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy, respectively. It was found that NaOH was a satisfactory catalyst and contributed to helping the liquefaction of algal biomass. The bio-oil from algal biomass was composed of many compounds, including carbohydrates, alcohol, hydroxybenzene, carboxylic acid, alkene, ester, and others. The mechanism of hydrothermal catalytic liquefaction was discussed. It was found that, comparing with the husk bio-fuel, the algal bio-oil as a promising alternative fuel was more close to the traditional diesel fuel in physicochemical properties. The novel research outcomes contribute to improving the yield of bio-oil from microalgae, reducing the cost of the bio-oil and accelerating the commercial application of the algal bio-oil in the near future.     

玉米秸秆颗粒燃料燃烧特性的试验研究

为了研究玉米秸秆颗粒燃料的燃烧特性,以一个小型反烧单元体炉为试验装置,分别进行了不同料层、不同水分、不同空气量下的燃烧试验,了解其燃烧特性,如点火时间、燃烧时间、燃烧过程及燃烧后的结渣现象。试验结果表明,玉米秸秆颗粒燃料易点燃,燃烧温度高,但燃烧时间短,结渣严重;料层高的玉米秸秆颗粒燃料燃烧时间相对长,但燃烧温度低,轻微结渣;干燥处理过的玉米秸秆颗粒燃料点火时冒黑烟现象明显减轻;加大燃烧过程的空气量时,玉米秸秆颗粒燃料不结渣。