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以竹材、稻壳、木屑为原料,通过常规热解结合快速热解研究生物质热解特性。结果表明,生物质常规热解的液体得率较低,相比而言竹材最高,稻壳最低,且热解温度是影响竹材和木屑热解的主要因素,其液体得率随温度的升高呈先增后减的变化规律;快速热解方面,利用居里点裂解仪和GC—MS在线分析竹材热解的液相组成,其组成以糠醛和酚类物质为主,它们分别来源于纤维素、半纤维素和木质素的热解。 相似文献
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以纤维素和橡树叶为研究对象,探索了蒙脱石催化作用下热解产物的变化规律及机理。结果表明:蒙脱石负载促进纤维素向β-消除路径转化,导致活化能增加、DTG (微商热重分析曲线)峰值温度升高和热解速率降低,而对橡树叶的热解过程影响较小;蒙脱石可催化热解液体的2次裂解,使液体产率降低,气体产率增加,而对固体产物产率的影响较小,其中热解气体以H2、CH4和CO2为主。蒙脱石表面和层间含有许多强酸性和弱酸性的Lewis (L)和Bronsted (B)酸性位点,可原位催化羧酸类物质发生脱羧基反应;同时对热解液体产物中糠醛和左旋葡聚糖酮的富集有明显的促进作用。 相似文献
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利用自行搭建的固定床热反应器对稻壳进行热解实验制备热解油, 采用两种不同极性的石英毛细柱对收油后的二氯甲烷溶液进行GC-MS检测。实验结果表明:热解终温对热解油品的组分种类几乎无影响, 但热解油产率随热解终温增大呈先升高后降低趋势;热解油二氯甲烷溶液的水相部分化合物种类相对较少, 主要物质为甲酸、乙酸和1-羟基-2-丙酮, 油相部分有机物种类极为复杂, 主要物质为糠醛、糠醇以及酚类和酮类物质;可凝结的热解有机气体主要在500~600℃发生二次裂解;对稻壳600℃热解油油相检测时发现:在RTX-5MS柱检测条件下, 组分中前5种化合物是糠醛、2-丁酮、乙酸、苯酚和2-甲氧基苯酚, 而在RTX-WAX 柱检测条件下, 前5种化合物是苯酚、2-甲氧基苯酚、4-乙基苯酚、乙酸和3-甲基苯酚。 相似文献
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为探究典型生物质原料纤维素与多氢原料聚乙烯共热解过程中官能团的相互作用及协同效应,本文利用傅里叶变换红外光谱仪、热裂解-气相色谱/质谱联用仪、热重-质谱及流化床对纤维素及其与聚乙烯混合共同热解实验产物进行分析。傅里叶变换红外光谱实验表明,纤维素红外谱图的主要基团为CH3、CH、CH2,多氢原料的加入均会提升碳氢基团的相对含量。热重-质谱实验表明纤维素的实验主要产物为C3H8,聚乙烯的加入会提升C2H4的离子流强度。热裂解-气相色谱/质谱联用实验表明,纤维素的热解产物以左旋葡聚糖为主,聚乙烯的加入使得纤维素中烃类的含量得到较大幅度的提升,HZSM-5的催化使得芳烃类产物的相对含量得到提升。流化床热解验证实验的总体趋势与PY-GC/MS实验一致,在纤维素与聚乙烯共热解的基础上再加入HZSM-5催化,可以得到最佳的实验效果。 相似文献
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通过浸渍的方式在纤维素上负载了四种金属氯化物(KCl、CaCl2、FeCl3和ZnCl2),采用Py-GC/MS装置对其进行快速热解并对热解气在线分析,考察各金属氯化物及其负载量对纤维素热解产物的影响。结果表明,负载金属氯化物能够显著降低纤维素的热解温度,其中负载CaCl2和FeCl3会抑制纤维素热解形成挥发性产物,而负载KCl和ZnCl2则不会。纯纤维素快速热解主要得到了以左旋葡聚糖为主的脱水糖以及一定量的呋喃类产物,和以羟基乙醛为主的小分子醛酮类产物。负载金属氯化物后都抑制了左旋葡聚糖的生成,其中KCl和CaCl2主要促进了纤维素解聚后脱水形成呋喃类产物,以及吡喃环开裂形成醛、酮、酸等小分子产物;FeCl3和ZnCl2则主要是促进纤维素解聚后形成脱水糖以及呋喃类产物。 相似文献
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玉米秆酶解残渣木质素热解实验研究 总被引:1,自引:0,他引:1
对玉米秆酶解残渣木质素进行热重分析,结果表明,木质素热裂解主要发生在180~500℃,综合考虑热解效率和液体产物产率最大化,选取快速热解实验的热解温度范围为500~600℃。并在实验室自行设计的装置上对木质素进行热解实验,在550℃时得到热解液体产物热解油最大产率,为30.9%。对热解油进行气相色谱―质谱分析,结果显示木质素热解产物相对简单,一级和二、三、四级热解油的成分主要是酮类和酚类;而电捕油中酮类很少,大部分是酚类,另有15.07%的2,3-二氢苯并呋喃。 相似文献
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以SBA-15为载体制备了固体磷酸,将其和纤维素机械混合后进行快速热解制备左旋葡萄糖酮(LGO)。通过Py-GC/MS(快速热解-气相色谱/质谱联用)实验,考察了催化热解温度、催化剂/纤维素比例对纤维素热解生成LGO以及其他产物的影响。实验结果表明,固体磷酸能够抑制纤维素热解形成左旋葡萄糖(LG)等产物,并大幅促进LGO的生成,从而高选择性地获得以LGO为主的热解产物。在热解温度为350℃以及催化剂/纤维素比例为1/1的条件下,可获得最高的LGO产率与相对含量,相对峰面积值高达68.6%。此外固体磷酸还能促进LG脱水形成LGO。 相似文献
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以SBA-15为载体制备了固体磷酸,将其和纤维素机械混合后进行快速热解制备左旋葡萄糖酮(LGO)。通过Py-GC/MS(快速热解-气相色谱/质谱联用)实验,考察了催化热解温度、催化剂/纤维素比例对纤维素热解生成LGO以及其他产物的影响。实验结果表明,固体磷酸能够抑制纤维素热解形成左旋葡萄糖(LG)等产物,并大幅促进LGO的生成,从而高选择性地获得以LGO为主的热解产物。在热解温度为350℃以及催化剂/纤维素比例为1/1的条件下,可获得最高的LGO产率与相对含量,相对峰面积值高达68.6%。此外固体磷酸还能促进LG脱水形成LGO。 相似文献
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Yanqiu Long Hui Zhou Aihong Meng Qinghai Li Yanguo Zhang 《Korean Journal of Chemical Engineering》2016,33(9):2638-2643
The interactions of biomass components (hemicellulose, cellulose, and lignin) during co-pyrolysis were investigated in a thermogravimetric analyzer (TGA) as well as a self-designed Macro-TGA with higher heating rate and larger amount of sample. The overlap ratio (OR) was used to evaluate the interaction of biomass components quantitatively. In TGA, the pyrolysis of xylan was not significantly affected by cellulose, whereas the pyrolysis of cellulose was markedly influenced by xylan. The interactions between xylan and lignin were weak with an overlap ratio of 0.9869, whereas co-pyrolysis of cellulose and lignin was strongly inhibited by interactions with the overlap ratio of 0.9737. In Macro-TGA, interactions between components were stronger than that in TGA due to more considerable heat and mass transfer effect. 相似文献
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The influence of temperature on the compounds existing in liquid products obtained from biomass samples via pyrolysis were examined in relation to the yield and composition of the product bio-oils. The product liquids were analysed by a gas chromatography mass spectrometry combined system. The bio-oils were composed of a range of cyclopentanone, methoxyphenol, acetic acid, methanol, acetone, furfural, phenol, formic acid, levoglucosan, guaiacol and their alkylated phenol derivatives. Thermal depolymerization and decomposition of biomass structural components, such as cellulose, hemicelluloses, lignin form liquids and gas products as well as a solid residue of charcoal. The structural components of the biomass samples mainly affect the pyrolytic degradation products. A reaction mechanism is proposed which describes a possible reaction route for the formation of the characteristic compounds found in the oils. The supercritical water extraction and liquefaction partial reactions also occur during the pyrolysis. Acetic acid is formed in the thermal decomposition of all three main components of biomass. In the pyrolysis reactions of biomass: water is formed by dehydration; acetic acid comes from the elimination of acetyl groups originally linked to the xylose unit; furfural is formed by dehydration of the xylose unit; formic acid proceeds from carboxylic groups of uronic acid; and methanol arises from methoxyl groups of uronic acid 相似文献
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《Fuel》2005,84(12-13):1494-1502
Al-MCM-41 type mesoporous catalysts were used for converting the pyrolysis vapours of spruce wood in order to obtain better bio-oil properties. Four Al-MCM-41 type catalysts with a Si/Al ratio of 20 were tested. The catalytic properties of Al-MCM-41 catalyst were modified by pore enlargement that allows the processing of larger molecules and by introduction of Cu cations into the structure.Spruce wood pyrolysis at 500 °C was performed and the products were analysed with the help of on-line pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). In addition, thermogravimetry/mass spectrometry (TG/MS) experiments were applied for monitoring the product evolution under slow heating conditions (20 °C/min) from 50 to 800 °C.Levoglucosan is completely eliminated, while acetic acid, furfural and furanes become quite important among cellulose pyrolysis products over the unmodified Al-MCM-41 catalyst. The dominance of phenolic compounds of higher molecular mass is strongly cut back among the lignin products. Both the increase of the yield of acetic acid and furan and the decrease of large methoxyphenols are repressed to some extent over catalysts with enlarged pores. The Cu modified catalyst performed similarly to the catalyst with enlarged pore size in converting the pyrolysis vapours of wood, although its pore size was similar to the unmodified Al-MCM-41. 相似文献
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Fagus sylvatica wood samples were treated in HCl‐catalyzed, acetic acid solutions. The effects of selected operational variables (catalyst concentration, reaction time and liquor to wood ratio) on pulp yield, composition of pulps and composition of pulping liquors were assessed using incomplete, second‐order, centred, factorial designs. Pulp composition was measured by the contents in cellulose, xylan and lignin. The concentrations of glucose, xylose and furfural in pulping liquors were also considered as experimental variables. Under selected conditions, pulps with 5.8% to 7.5% Klason lignin (kappa numbers in the range 25 to 33), 77.2% to 85.3% cellulose and 3.3% to 6.1% xylan were obtained at 45.8% to 50.0% pulp yield. The selected pulps showed good SCAN viscosity (723 to 814 mL/g) and alkaline resistances which were affected by the acetyl group content of samples (6.6 to 7.6 weight percent). 相似文献
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Xylooligosaccharides (XOS) were prepared by selective hydrolysis of the waste xylan, obtained from viscose fiber plants, using concentrated acetic acid. The influences of acetic acid concentration, reaction temperature, and reaction time on the yield and component profiles of XOS product were investigated. These results were further ascertained by designing orthogonal experiments. The hydrolysis of xylan residue was selective, since mainly xylooligosaccharide components were formed, with hardly any impure ingredients, except for a small amount of xylose and traces of furfural, in the hydrolyzed product. Reaction temperature was found to be the most significant factor, influencing the XOS yield. Accurate HPAEC–PAD analysis of component profiles indicated that a maximum XOS yield of 45.86% was achieved on hydrolysis of 33.77 g/L waste xylan using 20% acetic acid for 20 min at 140°C. The main XOS components obtained were xylobiose, xylotriose, and xylotetraose, which were more than xylopentaose and xylohexaose. 相似文献
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Kyung Yoen Won Byung Hwan Um Seung Wook Kim Kyeong Keun Oh 《Korean Journal of Chemical Engineering》2012,29(5):614-620
Dilute acid fractionation of barley straw improves dissolving hemicellulose fraction of the straw, while leaving the cellulose
more reactive and accessible to enzyme as a strategy of pretreatment. To characterize the fractionation process, the effects
of the acid concentration, temperature and reaction time on the hemicellulose removal as well as on the formation of by-products
(furfural, 5-hydroxymethylfurfural and acetic acid) were investigated. The optimum fractionation conditions of barley straw
were 1% (w/v) concentration of sulfuric acid, 158 °C of reaction temperature and 15 min of reaction time. Under the optimum
conditions, 87% of xylan was hydrolyzed and recovered in liquid hydrolyzate, which was 7% higher than that of the predicted
yield. The hydrolyzate contained glucose 2.44 g/L, arabinose 1.70 g/L, xylose 13.41 g/L, acetic acid 1.55 g/L, levulinic acid
0.03 g/L, 5-HMF 0.03 g/L and furfural 0.75 g/L. 相似文献
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生物质与废塑料共催化快速热解是制取轻质芳烃的重要途径。 采用不同种类的分子筛催化剂,首先研究了分子筛种类对杨木、生物质三组分和低密度聚乙烯(LDPE)单独催化快速热解轻质芳烃产率的影响,其次研究了生物质三组分与LDPE在共催化热解过程中的协同作用机理。结果表明:在杨木、生物质三组分和LDPE单独催化快速热解时,HZSM-5(25)催化剂体现出最高的轻质芳烃产率;在杨木和LDPE共催化快速热解时,随着LDPE质量的增加,轻质芳烃的产率呈先升高后降低趋势;在生物质三组分和LDPE共催化快速热解时,纤维素和半纤维素热解的呋喃类中间产物与LDPE热解的轻烯烃中间产物易发生“双烯合成”反应,表现出较强的协同催化作用,促进轻质芳烃的生成,而木质素则抑制轻质芳烃生成。 相似文献
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Yongchao Zhang Qingxi Hou Yingjuan Fu Chunlin Xu Annika I. Smeds Stefan Willför 《木材化学与工艺学杂志》2018,38(3):170-182
To promote the efficient utilization of lignocellulosic materials, one-step fractionation by formic acid-based organosolv process under pressure has been studied for converting lignocellulose in its main components. Lignin and hemicelluloses were selectively dissolved, while cellulose was not obviously degraded. Under optimized conditions (85% formic acid, a liquor-to-solid ratio of 7:1, and a temperature of 145°C for 45 min), this process provided a high efficient way to separate the main components of bamboo, obtaining 42.2% cellulose pulp, 31.5% lignin, 8.5% hemicellulose-rich fraction, 3.56% furfural and 3.80% acetic acid. Cellulose pulp with satisfying viscosity could easily be bleached to a high brightness of over 87% ISO with a short bleaching sequence, and had an acceptable paper strength properties. The recovered lignin fraction contained a small amount of carbohydrates and a considerable part of proteins and p-hydroxycinnamates. Additionally, the organic substances in hemicellulose-rich fraction obtained was composed of 95% carbohydrates, most of which was monosaccharides, as well as 5% lignin. 相似文献