萃取精馏分离苯-环己烷-环己烯的二元混合溶剂研究

采用N,N-二甲基乙酰胺(DMAC)、N-甲基吡咯烷酮(NMP)和γ-丁内酯萃取分离苯-环己烷-环己烯近沸程物系,考察了3种单一溶剂的分离性能,数据表明DMAC性能相对更优。在此基础上,研究了以DMAC为基础溶剂,NMP和γ-丁内酯为助溶剂的二元混合溶剂对苯-环己烷-环己烯物系的分离性能,结果表明:混合溶剂提高了从环己烷-环己烯中萃取分离苯的能力,但增大了从环己烷中分离环己烯的难度。当NMP和γ-丁内酯在二元混合溶剂中的质量分数分别为10%和25%时,其分离性能优于单一溶剂,整体分离效果也达到最优。     

离子液体萃取精馏分离乙醇-环己烷共沸物

在0.101 MPa压力下,测定了不同离子液体对乙醇-环己烷共沸物相对挥发度的影响,研究了溶剂比(萃取剂与原料液体积比)对体系相对挥发度、离子液体加入速率和回流比对萃取精馏的影响,按实验确定的最佳工艺条件进行了重复实验. 结果表明,离子液体作为萃取剂可以消除乙醇-环己烷物系的共沸点,提高该物系的相对挥发度. 采用[bmim]PF6作为萃取剂,溶剂比为0.5,离子液体加入速率为6 mL/min,回流比为3,可得到纯度大于99.8%的环己烷. 釜液采用闪蒸分离回收乙醇和离子液体,乙醇的回收率达99.9%以上. 离子液体的循环使用不影响分离性能.     

萃取精馏分离丙酮-环己烷共沸体系的模拟与实验

利用Aspen Plus对以DMSO为萃取剂的丙酮-环己烷共沸物系的萃取精馏进行了模拟研究。通过灵敏度分析工具,得到了丙酮-环己烷共沸物系的连续萃取精馏最优工艺条件:萃取精馏塔的理论板数36,质量回流比0.32,原料进料位置25,萃取剂进料位置7,萃取剂用量1 750 kg/h,溶剂回收塔的理论板数8,质量回流比0.21,进料位置5时,在最优工艺条件下,分离得到的环己烷质量分数可到99.5%,丙酮质量分数可到99.53%。同时通过间歇萃取精馏,对DMSO作为萃取剂的丙酮-环己烷萃取精馏进行试验验证,通过试验可以得到质量分数为95.35%的环己烷和质量分数为92.24%的丙酮,且二者回收率均可达65%以上,说明以DMSO为萃取剂,通过萃取精馏可以实现丙酮-环己烷共沸物系的有效分离。     

间歇萃取精馏分离环己烷-正丙醇的研究

首次研究了间歇萃取精馏方法分离环己烷-正丙醇二元共沸物。通过溶剂选择原理选出DMF作为分离此共沸物系的溶剂,采用UNIFAC模型对常压下环己烷-正丙醇物系和加入溶剂DMF后的物系进行气液平衡模拟,并进行了实验验证,其中模拟结果与实验数据吻合较好。通过间歇萃取精馏分离此共沸物的实验研究来进一步考察所选萃取剂的效果。结果表明,DMF能够消除环己烷-正丙醇共沸物系的共沸点,采用有30块理论板的填料塔,萃取剂进料位置为第4块板,溶剂质量比为1∶1,回流比为3∶1时,塔顶环己烷产品质量分数为96.2%,回收率为72.2%。     

加盐萃取精馏分离苯-环己烷

测定不同萃取剂和盐对苯-环己烷共沸物相对挥发度的影响,研究不同质量分数的盐和萃取剂与原料液体积比对苯-环己烷体系相对挥发度的影响以及萃取剂加入速率和回流比对加盐萃取精馏的影响,按实验确定的最佳工艺条件进行重复实验。结果表明:采用N,N-二甲基甲酰胺(DMF)作为萃取剂,加入质量分数为15%的KAc,萃取剂与原料液体积比为0.75,萃取剂加入速率为6 mL/min,回流比为3,可得到纯度大于98%的环己烷。与常规萃取精馏相比,加盐萃取精馏所需萃取剂与原料液体积比小,所得环己烷的纯度较高。塔底釜液经减压精馏,可得质量分数大于99.5%的苯和苯质量分数小于0.15%的加盐萃取剂。     

间歇萃取精馏分离环戊烷–四氢呋喃–环己烷

根据环戊烷–四氢呋喃–环己烷的汽液平衡关系,通过选择适当的溶剂(N,N–二甲基甲酰胺),提出了采用同一溶剂分离三元混合物的间歇萃取精馏方法.考察了溶剂比对该三元物系间相对挥发度的影响,进行了实验室小试研究.实验结果表明,所选溶剂N,N–二甲基甲酰胺可以增大环戊烷-四氢呋喃的相对挥发度,同时也可使四氢呋喃–环己烷共沸物的共沸现象消失,实验室萃取精馏小试可以得到纯度高于99%的环戊烷和环己烷产品.     

煤直接液化残渣的萃取和利用研究

根据煤液化残渣的组成特点,选取不同馏分段的煤液化油和煤焦油洗油作为溶剂进行了残渣萃取分离实验研究.结果表明,在常温下,溶剂和残渣质量比为2∶1时,馏程为137℃~213℃的煤液化油对煤液化残渣的萃取率(干燥基)为22.85%,与煤液化残渣中的正己烷可溶物含量相当;馏程为230℃~317℃的煤焦油洗油,对煤液化残渣的萃取率为44.63%,与煤液化残渣中的四氢呋喃可溶物含量相当.采用煤液化油和煤焦油洗油对煤液化残渣进行了两级萃取分离,得到了萃取物和萃余物,并分别在煤加氢液化循环溶剂和水煤浆制备等应用方面进行了探索性研究.     

加盐萃取-精馏耦合分离苯-环己烷共沸物

采用N,N-二甲基甲酰胺(DMF)+硫氰酸钾(KSCN)萃取分离苯-环己烷共沸物,并用常规间歇精馏处理富含苯的萃取液。考察了不同溶剂与原料液的体积比、盐质量分数对该体系分配系数及选择系数的影响,并进行了多级错、逆流萃取实验及精馏实验。实验结果表明:7级错流萃取可得摩尔分数大于97%(脱溶剂摩尔分数)的环己烷;5级逆流可得摩尔分数大于75%(脱溶剂摩尔分数)的环己烷;精馏后的萃取液,苯摩尔分数可达98%以上,DMF+KSCN摩尔分数可达96%以上。加盐萃取-精馏耦合分离苯-环己烷共沸物可得到令人满意的分离效果,是一种绿色节能的新方法。     

以二甘醇为萃取剂萃取精馏分离苯-环己烷共沸体系

本文基于Aspen Plus软件,对苯-环己烷共沸体系的萃取精馏过程进行模拟与条件优化。采用Sensitivity灵敏度分析考察了多个因素对分离效果与热负荷的影响。确定的最佳工艺方案为:全塔理论板数为30,原料和萃取剂分别在第15块和第3块理论板进料。在此工艺方案下:苯的分离效果达99.863%,萃取剂二甘醇的回收率达99.846%,模拟与优化结果为苯-环己烷共沸物连续萃取精馏分离过程的工业化设计和操作提供了理论依据和设计参考。     

环己烷-乙酸乙酯萃取精馏分离的研究

通过UNIFAC基团贡献法和氢键间相互作用,初步筛选二甲基亚砜(DMSO)作为萃取剂,通过萃取精馏分离环己烷与乙酸乙酯物系。在常压下模型模拟加入二甲基亚砜后环己烷与乙酸乙酯体系的汽液相组成,NRTL模拟结果与汽液平衡实验所得数据相似度高,结果表明二甲基亚砜作为萃取剂可以有效打破该共沸体系。同时进行间歇萃取精馏实验,填料理论塔板数为33,回流比1.0,溶剂比为1.0时可以得到质量分数为98.7%的环己烷,回收率为87.8%。最后在Aspen Plus软件帮助下研究二甲基亚砜连续萃取精馏分离环己烷-乙酸乙酯物系的工艺,萃取精馏塔塔顶环己烷的质量分数可达99.6%,溶剂回收塔塔顶乙酸乙酯的质量分数为99.5%,塔底回收二甲基亚砜套用,为进一步的工业应用提供参考。     

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.     

Ru/C催化作用下生物油在超临界乙醇中的提质

使用了两步加氢-超临界提质以及一步超临界提质两种方法对生物油进行提质,并进行了溶剂回收利用。实验结果表明经过这两种提质方法,生物油的物化性质均得到有效提升,提质后生物油中酸、酮和酚的相对含量明显下降,而醇、醚和酯类等理想产物的相对含量有显著上升。根据每步产物的GC-MS结果,对提质过程中所发生的反应进行了推测。相对于一步法提质所得到生物油,两步提质法所得到的提质生物油中醇和醚类的相对含量略高而酮、酚和酯类的相对含量略低。同时,相比于一步超临界提质,两步加氢-超临界提质过程中乙醇的消耗量有所降低。溶剂的回收利用在降低生物油提质所需要的乙醇含量的同时提高了提质产物中酯类的相对含量,这表明在较低的醇油比条件下超临界提质仍然是一种有效的生物油提质方法。     

La改性多级孔HZSM-5在线催化提质生物油

采用Na₂CO₃溶液对HZSM-5分子筛进行预处理，然后采用浸渍法对预处理后的HZSM-5进行不同负载量的La改性，通过XRD、BET、SEM-EDS和Py-IR等方法对改性前后的HZSM-5进行表征。利用改性前后的HZSM-5在两段式固定床反应器上进行生物质热解产物在线催化实验，对得到的生物油有机相进行理化特性和组成成分分析。结果表明，经过Na₂CO₃溶液处理后，使HZSM-5分子筛形成了含有微-介孔的多级孔孔道结构，La的改性未改变HZSM-5的MFI结构，但改变了分子筛的酸分布。随着La负载量的增加，生物油有机相产率、密度、运动黏度及氧含量先减小后增加，含氧化合物和羰基类化合物含量同样呈现先减小后增加的变化趋势。经过最佳质量分数为5%的La负载后的多级孔HZSM-5分子筛制得的生物油中，有机相高位热值高达37.7 MJ/kg，烃类物质含量达到了49.86%，含氧化合物和羰基类化合物含量分别减少了32.43%和57.03%。     

水合CaO对微拟球藻催化热解制备生物油的影响

以水合CaO为催化剂,在管式炉内研究了微拟球藻的催化热解.考察了催化剂用量对微拟球藻热解产物及油品组成的影响,并通过直接再生和强化再生研究了催化剂的再生特性.结果表明:随着水合CaO用量逐渐加大,生物油性能明显改善.在催化剂/藻质量比为1:3时催化热解得到的生物油产率为28.5%,具有含氧量低、热值高、运动黏度低、含水率低等优点.与直接热解油相比,催化热解油中羧基化合物和羟基化合物含量均有明显下降,而脂肪烃和芳香烃含量均显著增加.第1次和第2次循环再生实验中,直接再生催化剂依然具有较高的催化活性.通过在直接再生过程中引入水洗强化步骤,可对再生催化剂表面进行更新,并降低其表面的碱金属含量,明显改善再生催化剂所催化热解的油品质量,提高再生催化剂活性.     

Ball milling promoted direct liquefaction of lignocellulosic biomass in supercritical ethanol

In the present work, ball milling was applied for the pretreatment of lignocellulose to obtain high conversion and bio-oil yield in supercritical ethanol. Ball milling substantially decreased the crystallinity and particle size of lignocellulose, thereby improving its accessibility in ethanol solvent. An increased bio-oil yield of 59.2% was obtained for the ball milled camphorwood sawdust at 300°C, compared with 39.6% for the original lignocellulose. Decreased crystallinity significantly benefited the conversion of the cellulose component from 60.8% to 91.7%, and decreased particle size was beneficial for the conversion of all components. The obtained bio-oil had a high phenolic content, as analyzed by gas chromatography-mass spectrometry. Methoxylation and retro-aldol condensation were observed during alcoholysis, and the reaction pathways of lignocellulose in supercritical ethanol were attributed to the action of free radicals.     

生物质油加氢脱氧精制研究进展

随着石油能源渐趋匮乏,生物质高温裂解制备生物质油备受关注。而生物质油中氧含量高达40%,这将影响生物质油的稳定性、极性、热值、粘度和酸性等,应必须对其进行加氢脱氧精制处理。文中介绍了裂解生物质油的组成分布和特点,阐述了裂解生物质油加氢脱氧精制的反应过程和影响因素。     

Fuel properties of bio-oil/bio-diesel mixture characterized by TG, FTIR and 1H NMR

There has been an increasing interest in alternative fuels made from biomass which is abundant and renewable. Bio-oil and bio-diesel seem to be such promising liquid fuels. Bio-oil produced by fast pyrolysis of biomass is highly viscous, acidic, and has high water content. To overcome these problems as a fuel, a method of emulsifying bio-oil with bio-diesel was performed in the previous paper, and a stable mixture of bio-oil and bio-diesel was successfully prepared. In this paper, several properties of the mixture are discussed by using TG, FTIR and ¹H NMR. The results show us that, compared with crude bio-oil, some properties of bio-oil/bio-diesel mixture such as water content, acid number, viscosity are much improved. The thermal decomposition of the mixture under air/nitrogen is shown using a thermogravimetric analyzer (TGA). Further information about the functional groups is exhibited through Fourier Transform infrared spectrometer (FTIR) and nuclear magnetic spectroscopy (NMR).     

生物质油改性方法研究进展

生物质快速裂解液体产物生物油(简称生物质油),具有水含量高、氧含量高、热值低、粘度大、热不稳定和化学不稳定等特性,在一定程度上影响了其广泛应用,因此必须通过精制改善其品质.按生物质快速裂解的反应过程,将提高生物质油品质的方法归纳为三类:第一类(反应前),快速裂解反应前,原料脱水和脱碱金属处理;第二类(反应中),快速裂解反应过程中,生物质油蒸汽不经冷凝直接改质;第三类(反应后),快速裂解反应完成后,采用对收集到的生物质油催化加氢、催化裂解、催化酯化、乳化、添加溶剂或添加抗氧化剂等方法进行改质.     

An in situ reduction approach for bio-oil hydroprocessing

An in situ reduction treatment, combination of reduction and esterification, was investigated to refine bio-oil. Over Raney Ni and zeolites-supported noble metal (Pd and Ru) catalysts, the reductant formic acid decomposed into hydrogen and carbon dioxide, and then hydrogen reduced the bio-oil while compressible CO₂ dissolved in methanol to form a CO₂-CH₃OH expanded liquid. The results showed that Raney Ni and zeolites-supported Ru were highly active in this heterogeneous catalytic system. The reactions preformed at 150-230 °C for 5-7 h would give a better upgraded bio-oil with a high yield of 80-90 wt.%. The unsaturated components in bio-oil were reduced substantially without obvious coke formation, and the oxygen content was lowered by ca. 5 wt.%. Organic acids were converted into esters through the esterification with methanol, and the properties of hydrogenated bio-oil were improved: the pH value increased from 2.17 to ca. 4.5; the higher heating value approached to 22 MJ/kg, and the viscosity decreased from 5.31 to ca. 4.0 mm²/s.     

Biofuels from waste fish oil pyrolysis: Chemical composition

In a previous study, waste fish oil was converted into bio-oil by a fast pyrolysis process at 525 °C in a continuous pilot plant reactor with 72-73% yield. The bio-oil was distilled to obtain light bio-oil and heavy bio-oil and these biofuels were characterized in terms of their physico-chemical properties. In this study, the chemical composition of light bio-oil and heavy bio-oil was determined using GC-FID, GC-MS, ¹H and ¹³C NMR techniques. The GC-MS analysis of waste fish oil showed the main composition of fatty acids to be the following: C_16:0 (15.87%), C_18:2 (20.96%), C_18:1 (17.29%), C_20:5 (5.11%), C_20:1 (7.59%), C_22:6 (4.53%), C_22:1 (10.42%) and others. The GC-FID analysis of the light bio-oil showed 482 compounds that were PIONA classified as paraffins (4.48%), iso-paraffins (8.31%), olefins (26.56%), naphthenes (6.07%) and aromatics (16.86%). The heavy bio-oil had a similar chromatographic profile as diesel oil, with a high content of carboxylic acids and olefins. These results are in good agreement with those for the gasoline and diesel oil fractions of petroleum.