PROBABILISTIC MODELLING OF LIGNIN LIQUEFACTION

ABSTRACT

The results of the thermal and catalytic reactions of lignin model compounds are used in the a priori prediction of its liquefaction. Lignin was defined probabilistically as an ensemble of single ring aromatics with substituents on each of their six ring positions. Elements in a substituent vector x¹, for each ring position i, were matched into all possible combinations to describe lignin. Initial number fractions, or probabilities, for each vector element were ascertained through inspection of lignin structural data. The reaction of lignins altered the probabilities within each substituent vector, and reaction products were also calculated by matching all combinations of vector elements for each ring position. Model compound results provided the identities and rates of change of vector elements.

This simulation of lignin liquefaction predicted the yields of permanent gases, aqueous liquids, single- and two-ring phenolic products, and a carbonaceous residue. The impact of the distribution of oligomeric sizes on catalyst effectiveness was probed.     

HYDROPROCESSING LIGNIN AND LIGNIN MODEL COMPOUNDS: PRODUCTS, KINETICS, AND CATALYST AGING

The hydroprocessing reactions of kraft lignin and four of its model compounds, o-hydroxydiphenylmethane (OHD), diphenylmethane (DPM), 4-phenoxyphenol (PP), and 4-methylguaiacol (MG) were studied over a sulfided CoMo/γ-Al₂O₃ catalyst. The reactions of OHD were also studied over sulfided Ni-Mo/γ-Al₂O₃, Ni-W/γ-Al₂O₃, and Ni-Mo/zeolite catalysts. Reaction pathways, kinetics, and catalyst deactivation were resolved. Experiments with the actual kraft lignin substrate showed that catalytic hydroprocessing led to higher yields of single-ring products and lower yields of light gas compared to hydropyrolysis alone. The CoMo/γ-Al₂O₃ catalyst increased the selectivity to non-coking monophenolics and hydrocarbon products. The model compound results permitted interpretation. The hydroxyl substituents on OHD and PP directed bond cleavage strongly. The atom linking the two aromatic rings remained almost exclusively with the unsubstituted ring after cleavage. The substituent increased reactivity by at least an order of magnitude. The catalytic reactions of OHD, DPM, and PP were 10³-10⁴ times faster than their thermal reactions. Deoxygenation was appreciable in these reactions and in the catalytic hydroprocessing of MG. Collectively, these results suggest that the improved activity and selectivity in catalytic lignin liquefaction is due to enhancement of link cleavage and the transformation of coking dioxygen-substituted phenolic coke pecursors (e.g., catechols and guaiacols) to non-coking phenols. Hydrotreating catalysts with alumina supports appear suitable for lignin conversion. The highly active and rapidly deactivating zeolite-supported hydrotreating catalyst afforded a complex mixture of products. Regeneration of the alumina-supported catalysts would be required.     

杨木粉和大豆油在超临界甲醇中的共炼研究

对杨木粉与大豆油或脂肪酸甲酯在超临界甲醇中的共炼进行了研究,以验证油脂及其甲酯对杨木粉液化的促进作用。研究结果表明,大豆油及脂肪酸甲酯都对杨木粉的分解率有明显促进作用,且大豆油的促进效果要优于脂肪酸甲酯。更进一步研究表明,共炼能够同时提高木粉中纤维素、半纤维素和木质素的分解率,其中木质素的相对分解率提高幅度最大。生物质共炼产物在经过低温减压蒸馏、石油醚萃取分离后得到两部分：生物轻油,以油脂衍生物为主;生物重油,以杨木粉液化产物为主。如果原料中采用的油脂不饱和度越高,则产物中会含有越多的甘油二酯沸程的化合物,这部分甘油二酯沸程化合物主要是有油脂衍生物与杨木粉液化产物缩合而成。另外,共炼所得到的生物重油产率要远高于杨木粉在超临界甲醇中直接液化的产率,本文对可能的原因进行了分析。     

MODELING LIGNIN LIQUEFACTION 1. CATALYTIC HYDROPROCESSING OF LIGNIN-RELATED METHOXYPHENOLS AND INTERAROMATIC UNIT LINKAGES

The reactions of two sets of lignin model compounds over a sulfided CoOMoO3/γ-Al2O3 catalyst were studied. The first set mimicked lignin methoxyphenol residues and comprised 4-methyl-guaiacol, 4-methyl catechol, eugenol and vanillin. Deoxygenation and hydrogenation were facile and led to ultimate molar yields of single-ring products as high as 0.70. The selectivity to single-ring products increased with increases in temperature, o-hydroxydiphenylmethane, phenyl ether and o,o'-biphenol constituted the second set that mimicked thermally stable lignin bonds.Fragmentation of o-hydroxydiphenylmethane and phenyl ether occurred readily; o,o'-biphenol reacted to dibenzofuran.

These results suggest that the single-ring products obtained from catalytic liquefaction of lignins should be more desirable than those obtained from pyrolysis because of both higher yields and reduced complexity.     

多环芳烃指纹参数在催化裂化过程中的应用

采用气相色谱-质谱法分析1-甲基萘/戊基苯、四氢萘两种反应体系的烷基萘含量,发现α位和β位烷基萘质量分数随着反应转化率的升高而增加,而且不同取代位烷基萘质量分数之比（烷基萘参数）可以反映反应体系转化率的高低。进一步研究发现,不同体系的烷基萘反应机理相同,并且烷基萘产物分布受到分子筛孔道的限制。提取5种不同减压馏分油反应后的液体产物中烷基萘、烷基菲的含量信息,发现烷基萘参数与油品转化率的线性关系较好,而烷基菲参数与油品转化率的线性关系较差,因此烷基萘参数更适合作为反映减压馏分油转化率高低的指标。     

MODELING LIGNIN LIQUEFACTION 1. CATALYTIC HYDROPROCESSING OF LIGNIN-RELATED METHOXYPHENOLS AND INTERAROMATIC UNIT LINKAGES

ABSTRACT

The reactions of two sets of lignin model compounds over a sulfided CoOMoO3/γ-Al2O3 catalyst were studied. The first set mimicked lignin methoxyphenol residues and comprised 4-methyl-guaiacol, 4-methyl catechol, eugenol and vanillin. Deoxygenation and hydrogenation were facile and led to ultimate molar yields of single-ring products as high as 0.70. The selectivity to single-ring products increased with increases in temperature, o-hydroxydiphenylmethane, phenyl ether and o,o’-biphenol constituted the second set that mimicked thermally stable lignin bonds.Fragmentation of o-hydroxydiphenylmethane and phenyl ether occurred readily; o,o’-biphenol reacted to dibenzofuran.

These results suggest that the single-ring products obtained from catalytic liquefaction of lignins should be more desirable than those obtained from pyrolysis because of both higher yields and reduced complexity.     

生物质水热液化机理研究进展

介绍了生物质水热液化的机理及国内外最新研究进展。在对聚合单体如葡萄糖、木糖和氨基酸等的水热液化机理阐述分析的基础上,分析纤维素、半纤维素、木质素、蛋白质等高分子聚合物的水热液化机理,最后介绍生物质中含量相对较少却很重要的油脂及其衍生物在水热条件下的反应机理。     

COAL LIQUEFACTION WITH ANTHRACENE OIL. INFLUENCE OF SOLVENT PRETREATMENT, TEMPERATURE, CATALYST AND PRESSURE

The effect of solvent pretreatment, temperature, a CoMo/Al₂O₃ catalyst and pressure on coal liquefaction with anthracene oil has been evaluated. The experiments were conducted in a 500 ml autoclave with 10 g of a Spanish subbituminous A coal. 30 g of solvent, 1 hour reaction time and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The behaviour of anthracene oil as coal liquefaction solvent is very much enhanced by prehydrogenating it and by the addition ot an active catalyst. The influence of temperature depends on the operating conditions such as solvent pretreatment, catalyst, pressure etc. The addition of an active catalyst greatly improves conversion and the quality of the liquefaction products and diminishes repotimerization reactions. Hydrogen pressure is essential for coal liquefaction with anthracene oil, although over 16 MPa no further increase in coal conversion is observed.     

COAL LIQUEFACTION WITH ANTHRACENE OIL. INFLUENCE OF SOLVENT PRETREATMENT,TEMPERATURE, CATALYST AND PRESSURE

ABSTRACT

The effect of solvent pretreatment, temperature, a CoMo/Al₂O₃ catalyst and pressure on coal liquefaction with anthracene oil has been evaluated. The experiments were conducted in a 500 ml autoclave with 10 g of a Spanish subbituminous A coal. 30 g of solvent, 1 hour reaction time and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The behaviour of anthracene oil as coal liquefaction solvent is very much enhanced by prehydrogenating it and by the addition ot an active catalyst. The influence of temperature depends on the operating conditions such as solvent pretreatment, catalyst, pressure etc. The addition of an active catalyst greatly improves conversion and the quality of the liquefaction products and diminishes repotimerization reactions. Hydrogen pressure is essential for coal liquefaction with anthracene oil, although over 16 MPa no further increase in coal conversion is observed.     

木质素醇醚非离子表面活性剂的合成及性能

以造纸废液中提取的碱木素为原料合成了木质素醇醚非离子表面活性剂。确定了由中间体木素醚合成产品的最佳工艺条件为 :醚醇摩尔比为 1∶ 1 .2 ,反应温度为 1 45℃ ,反应时间为 1 h。测定了产品的红外光谱 ,并对其表面活性、乳化性、增溶性、泡沫高度等进行了研究。     

棕榈酸化油与木粉在超临界甲醇中共炼的研究

以棕榈酸化油和木粉为原料,在超临界甲醇条件下进行共炼反应,考察反应时间、反应温度、搅拌速率对木粉分解率、气化率、轻油产量和重油产量的影响,并对共炼反应条件进行优化。结果表明:在反应温度为300~320℃、反应时间为15~30min的条件下,共炼反应中木粉的最大液化率可达53.0%,油脂转化率达到100%;与在甲醇中直接液化相比,反应体系中加入棕榈酸甲酯共炼,木粉中纤维素、半纤维素和木质素的分解率分别提高18.9%,11.2%,25.0%。     

三次采油用烷基苯磺酸盐结构与性能的关系研究

通过合成不同结构的系列烷基苯磺酸盐,研究了不同结构烷基苯磺酸盐与烷烃、原油的界面活性,结果表明表面活性剂的分子结构(碳链长度,取代基大小,苯环位置)均对油水界面活性有很大影响,并且具有一定规律.研究了弱碱体系不同结构表面活性剂的油水界面活性规律,通过对烷基苯原料的大量筛选以及磺化合成工艺的优化,合成出适合我国石蜡基原油(以大庆原油为代表)、中间基原油(以大港原油为代表)的弱碱体系的烷基苯磺酸盐主剂配方SY-D1和SY-G2,合成的烷基苯磺酸盐主剂配方能在较宽的Na2CO3浓度范围(对大庆油水浓度为0.4%～1.0%,对大港油水浓度为0.2%～1.0%)和活性剂浓度范围(对大庆油水为0.025%～0.2%,对大港油水为0.05%～0.3%)与原油形成超低界面张力,其稀释能力强、用量少,且性能稳定.图10表1参3     

三次采油用烷基苯磺酸盐结构与性能的关系研究

通过合成不同结构的系列烷基苯磺酸盐,研究了不同结构烷基苯磺酸盐与烷烃、原油的界面活性,结果表明:表面活性剂的分子结构(碳链长度,取代基大小,苯环位置)均对油水界面活性有很大影响,并且具有一定规律。研究了弱碱体系不同结构表面活性剂的油水界面活性规律,通过对烷基苯原料的大量筛选以及磺化合成工艺的优化,合成出适合我国石蜡基原油(以大庆原油为代表)、中间基原油(以大港原油为代表)的弱碱体系的烷基苯磺酸盐主剂配方SY-D1和SY-G2,合成的烷基苯磺酸盐主剂配方能在较宽的Na2CO3浓度范围(对大庆油水浓度为0.4％~1.0％,对大港油水浓度为0.2％~1.0％)和活性剂浓度范围(对大庆油水为0.025％~0.2％,对大港油水为0.05％~0.3％)与原油形成超低界面张力,其稀释能力强、用量少,且性能稳定。图10表1参3     

高级脂肪胺改性木质素季铵盐的合成及表征

实验以十二烷基二甲基叔胺、环氧氯丙烷为原料,合成中间体(2,3-环氧丙基)十二烷基二甲基氯化铵,中间体在丙酮介质中与氧化磺化木质素发生O-烷基化反应,生成木质素表面活性剂。探讨了反应介质、物料比、反应时间、温度等影响因素。实验结果表明,O-烷基化反应在丙酮均相介质中进行,改善了反应物的溶解性,提高了反应效率;反应温度为55℃,反应时间为3 h;n(木质素)∶n(中间体)=1∶1.1时,产物中含氮量达2.28%。基本表面物化性能测试表明,高级脂肪胺改性木质素产物的表面活性较好,表面张力为17 mN/m,较木质素43 mN/m明显降低。     

采用密度泛函理论研究甲基噻吩在硫化钼团簇上的吸附行为

利用密度泛函理论研究了噻吩和甲基噻吩在硫化钼团簇的不饱和钼上的吸附行为,考察甲基对吸附效果的影响。结果表明：平行吸附比垂直吸附更稳定;噻吩和甲基噻吩在Mo16S32团簇上的平行吸附能力由大到小的顺序为2,3-二甲基噻吩>3-甲基噻吩>3,4-二甲基噻吩>2,4-二甲基噻吩>噻吩>2-甲基噻吩>2,5-二甲基噻吩;噻吩上含有一个甲基时,甲基位于3位有利于吸附,位于2位不利于吸附;噻吩上含有两个甲基时,吸附能力随着两个甲基间的距离增大而减小;通过键长、Mayer键级、Mulliken布局数分析可知,吸附后甲基噻吩环上C－S的键长增加、键级减弱,噻吩环上各原子杂化轨道上的电子流向Mo原子,Mo原子部分d轨道上的电子反馈到噻吩环的反键轨道,甲基噻吩得到活化,有利于后续的噻吩环加氢亲电反应。     

烷基取代基对烷基四氢萘供氢能力影响的分子模拟

采用基于密度泛函理论的量子化学从头算法,计算了不同类型1-烷基四氢萘分子中α位C-H键断裂的反应能垒和反应热,讨论了1-烷基四氢萘的供氢能力,并考察了1-烷基四氢萘分子中烷基的链长和异构化程度对该α位C-H键断裂的影响。结果表明,与四氢萘相比,1-甲基四氢萘分子中甲基旁α位C-H键更易断裂,因此1-甲基四氢萘的供氢能力比四氢萘更强。如果1-烷基四氢萘分子中的烷基取代基不影响其旁边α位C-H键断裂产物自由基的p-π共轭,该烷基的链长及异构化程度的变化对α位C-H键断裂的影响不大,也即对1-烷基四氢萘的供氢能力的影响很小;1-叔丁基四氢萘中的叔丁基破坏了α位C-H断裂产物自由基的p-π共轭结构,导致1-叔丁基四氢萘的供氢能力低于四氢萘。     

IRON COMPOUNDS AND C0-Mo/Al2O3 CATALYSTS: ACTIVITY IN DIRECT HYDROGENATION OF A SUBBITUMINOUS A COAL WITH AN H-DONOR SOLVENT

The effectiveness of different catalysts were compared in coal liquefaction experiments using a 250 ml stirred autoclave, 10 g of a Spanish Subbituminous A coal, 1 hour reaction time, 17 MPa operating pressure, 400 rpm stirring speed, at 425 and 450 °C with 2/1 and 3/1 tetralin/coal ratio. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue using pentane, toluene and THF as extractive solvents. Three iron-oxide containing catalysts: red mud, an Fe2O3 aerosol and Cottrell ash (by-product of the aluminium industry); and three alumina supported catalysts: CMA, which is a conventional CoMo/Al2O3 catalyst, CZMA which in addition contains Zn as a second promoter, and CZMFA which has the alumina acidified with fluorine and also contains Zn, were compared. It has been reported that the addition of Zn and of F enhances the HDS, cracking, hydrocracking or hydrogenating activities of CoMo/Al2O3 catalysts in experiments with pure compounds. The objective of this study was to determine if the addition of Zn and of F has also a beneficial effect in the catalyst activities in coal liquefaction, and also to compare cheap iron containing catalysts with the more sophisticated and expensive alumina supported ones.

The results showed that 1) Catalysts effects depend on the operating conditions used, and that with tetralin, a strong H-donor solvent, they never are very pronounced. 2) The supported catalysts have higher activities in coal liquefaction than the iron ones, but there are no significant differences among the catalysts within each group. 3) Zn, which is a cheaper metal than Co, can substitute succesfully for half the amount of Co and retain the activity of the CoMo/Al2O3 catalyst in coal liquefaction. 4) The addition of F to the CoMo/Al2O3 catalyst does not show a benefecial effect     

双咪唑环离子液体的制备及其正己烷异构化性能

设计合成了3种分别含甲基、乙基和丁基取代基的双咪唑环离子液体前驱体M₁、M₂和M₃,并对其进行核磁共振(¹H NMR和¹³C NMR)、高分辨质谱(ESI-MS)和同步热分析(TG/DTG/DSC)等表征。基于前驱体M₁、M₂和M₃合成了一系列双咪唑环离子液体催化剂AlCl₃/M₁、AlCl₃/M₂和AlCl₃/M₃,利用紫外-可见光谱(UV-visible)和乙腈红外(CAN-IR)表征方法对其酸性进行了研究。在此基础上研究取代基对正己烷异构化性能的影响并优化其反应工艺条件。结果表明：乙基为取代基的双咪唑环离子液体所合成的催化剂AlCl₃/M₂具有较多的BrÖnsted酸和Lewis酸位,有助于异构化反应的进行;在AlCl₃与前驱体M₂中Cl^-的摩尔比为2.1∶1、反应温度30 ℃、反应时间10 h和剂/油质量比1∶1的最佳工艺条件下,正己烷转化率为74.52%,异己烷选择性和收率分别为29.51%和21.99%。     

支链多烷基苯磺酸钠的合成与表面活性研究表面活性研究

以乙苯、间二甲苯及间二异丙基苯为原料,经酰化、格氏反应、催化加氢及磺化4步反应,合成了2种支链三烷基苯磺酸钠和1种支链双烷基苯磺酸钠,总收率均大于40.5%。在烷基苯磺酸盐分子中,主链(—CHR_3R_4)取代在苯环的1位上,短链 R_1和 R_2分别取代在2位和4位上。研究了中间体6-(2,4-二甲基苯基)-6-十二醇的催化加氢条件,结果表明:当反应温度为20～50℃,氢气压力高于1.0 MPa,w(0.5%Pd/C)大于5%时,支链三烷基苯的收率最高。测定了30℃时支链多烷基苯磺酸钠在盐溶液中的表面活性。     

CoMo/Al2O3催化剂柴油加氢脱芳烃集总反应动力学模型

为满足生产国六标准车用柴油的需要,采用等温高通量反应器,对加氢精制催化剂CoMo/Al2O3上的柴油加氢脱芳烃(HDA)动力学进行了研究。考察了反应温度、氢分压、氢/油体积比、空速等因素对柴油加氢脱芳烃反应的影响。根据芳烃加氢反应机理将柴油中的芳烃化合物按所含芳环个数分成了三集总。在此基础上,建立了考虑竞争吸附影响的集总反应动力学模型,并采用鲍威尔优化算法确定了模型参数。结果表明,所得动力学模型与实验结果吻合良好。进一步的验证结果表明,所建动力学模型能够很好地预测柴油加氢脱芳烃过程,所得模型可为柴油加氢脱芳烃反应的操作优化提供技术支撑。