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.     

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.     

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.     

木质素表面活性剂及木质素磺酸盐的化学改性方法

介绍了利用造纸工业的主要副产品木质素制取表面活性剂以及对木质素磺酸盐的几种有效的化学改性方法与产品应用途径 ,给出了用木质素改性制备水煤浆添加剂的实例。     

天然气液化工艺的选择

液化天然气在天然气的远洋运输，边远气田气体的利用以及城市燃气调峰中起到了重要的作用。本文概述了液化天然气的净化和液化工艺，对每种工艺的优缺点进行了分析比较，并指出了液化工艺的新的发展动向。另外，对新疆呼图壁、彩南、莫北三个油气田所产的天然气提出了液化方案。     

煤液化残渣加氢性能

通过含大量沥青质的煤液化残渣在微型反应釜的加氢实验,考察了温度、气氛、H2初压以及反应时间对煤液化残渣中油(Oil)、沥青质(PAA)和四氢呋喃不溶有机质(THFIS)加氢性能的影响.结果表明,煤液化残渣中的PAA和THFIS可进一步加氢转化成Oil,煤催化液化残渣与煤非催化液化残渣中的PAA最高转化率分别为77.43%和80.54%;N2压的存在能促进煤液化残渣中THFIS转化成PAA,高压H2有利于THFIS和PAA加氢转化成Oil.煤催化液化残渣和煤非催化液化残渣的最佳的加氢温度均为450℃,最佳的H2初压均为6 MPa,最优的反应时间分别为60 min和30 min.     

ELEMENTAL COMPOSITION OF ASPHALTENES FROM COAL LIQUEFACTION

The elemental composition (C, H, N, S, O) of asphaltenes isolated from coal liquefaction experiments carried out at different temperatures and tetralin/coal ratios has been determined. The liquefaction experiments were conducted in a 250 ml autoclave, with 10 g of a Spanish subbituminous A coal, for 1 hour, and at 17 ± 1 MPa operating pressure and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The % S and % O are lower in asphaltenes than in coal, while the % C and % N are higher and % H depends on the temperature and tetralin/coal ratio used. On the other hand asphaltenes % C decreases, and % H and % O increase as the tetralin/coal ratio is raised at every temperature except 475 °C, while % S and % N do not have a clear variation.     

火烧油层物理模拟的研究

火烧油层法有与蒸汽气采法不同的机理和特点，它作为常规稠油，超稠油开采方法的补充，目前在国内外油田现场正不断得到应用，相应的实验室技术－火烧物理模型及其应用研究也不怕加强。除介绍了火烧油层法的机理和特点外，主要介绍了火 物理模拟装置，火烧物理模拟相似准则及三大燃烧系数和其它物理模拟试验可得到的结果，如火烧经济指标等。     

KINETICS OF THERMAL LIQUEFACTION OF SEYITÖMER LIGNITE

Kinetics of non-catalytic liquefaction of Seyitomsr lignite has been investigated under hydrogen pressure, using tetralin as a Bolvent in a laboratory Bcale batch autoclave reactor.

In the first set of experiment hydrogen initial pressure and reaction temperature were kept constant, the reaction time and coal/aolvent ratio were changed at five and three levels espectively. In the second set of experiments coal/solvent ratio was kept constant and hydrogen initial pressure, reaction temperature and time were individually changed at four levels. The produot was analyzed in terms of total conversion, liquid yield and liquid product distribution determined as preasphaltenes, asphaltense and oila. A satisfactory correlation was obtained using the kinetic model proposed by Shalabi et al (1979).     

DIRECT LIQUEFACTION OF WOOD BY CATALYST AND WATER

Wood powder suspended in water was directly liquefied in the presence of nickel carbonate or potassium carbonate without a reducing agent like hydrogen and/or carbon monoxide. Heavy oils with carbon and hydrogen contents of about 80% were produced and their heats of combustion ranged from 29.3 to 33.4 MJ/kg. Total carbon recovery in the form of heavy oils was about 24%.     

STRUCTURAL GROUP ANALYSIS OF PRODUCTS FROM TWO-STAGE LIQUEFACTION OF HIGHVALE COAL

ABSTRACT

Products from liquefaction of Highvale Coal (Alberta. subbituminous) in anthracene oil and recycled product, with iron oxide catalyst, were studied using a structural group analysis method. The various functional groups were determined using a combination of proton NMR. carbon-13 NMR. IR. elemental analysis and nitrogen titration analysis. The liquefaction reactions in anthracene oil and in recycled product oil were compared on the basis of three solvent quality Indices and the predominant structural groups in the resulting liquids. The results show that major structural changes occur at both stages of liquefaction. Processing in anthracene oil showed much greater structural changes than liquefaction in the recycled product. The structural profiles Indicated a reduction in aromatic structures and a dramatic increase in aliphatic and naphthenic structures during processing in anthracene oil. These changes were attributed to the hydrogenation of aromatic structures and the dissolution of aliphatic and naphthenic compounds. Liquefaction in recycled product showed less significant changes in structural composition but resulted in a better quality product in terms of the amount of distillable oils, transferable protons and hydrogen to carbon ratio. This improvement was attributed to the improved availability of donatable hydrogen in the recycled product.     

MANAGEMENT OF COAL MACERALS IN THE LIQUEFACTION OF LOW RANK COALS

ABSTRACT

Three Alberta subbituminous coals were selected to investigate the contribution of different macerals to liquefaction. These coals represent the full range of geographic, rank and geological variations present In the Alberta Plains Coal Region. In addition, for comparison, two U.S. lignites (Texas and North Dakota) were included in these investigations. To enhance maceral concentration, density fractionation was carried out on these samples. Though liquefaction yields appear to increase with increase in vitrinite (huminite) content, a clear-cut correlation between conversion and maceral content is not established because of (a) uncertain behaviour of semi-inert macerals and (b) differences in behaviour within the vitrinite (huminite) macera1 group.     

STRUCTURAL GROUP ANALYSIS OF PRODUCTS FROM TWO-STAGE LIQUEFACTION OF HIGHVALE COAL

Products from liquefaction of Highvale Coal (Alberta. subbituminous) in anthracene oil and recycled product, with iron oxide catalyst, were studied using a structural group analysis method. The various functional groups were determined using a combination of proton NMR. carbon-13 NMR. IR. elemental analysis and nitrogen titration analysis. The liquefaction reactions in anthracene oil and in recycled product oil were compared on the basis of three solvent quality Indices and the predominant structural groups in the resulting liquids. The results show that major structural changes occur at both stages of liquefaction. Processing in anthracene oil showed much greater structural changes than liquefaction in the recycled product. The structural profiles Indicated a reduction in aromatic structures and a dramatic increase in aliphatic and naphthenic structures during processing in anthracene oil. These changes were attributed to the hydrogenation of aromatic structures and the dissolution of aliphatic and naphthenic compounds. Liquefaction in recycled product showed less significant changes in structural composition but resulted in a better quality product in terms of the amount of distillable oils, transferable protons and hydrogen to carbon ratio. This improvement was attributed to the improved availability of donatable hydrogen in the recycled product.     

COMPARISON OF COAL LIQUEFACTION IN BATCH AND CONTINUOUS REACTORS

Liquefaction of Akabira coal with a sufficient amount of tetralin was conducted in a 27 cm³ batch reactor and two types of continuous reactors - a 5000 cm³stirred tank reactor and a 800 cm³ tube reactor. These reactors were mainly operated at 673°K and 5.4 MPa. The batch reactor was heated at different rates from 4°K/nrin to 150°K/min to examine the effects of the heating rate on the conversion of coal to benzene solubles. Conversions in the continuous reactors were measured together with the residence time distributions of coal particles.

In the batch reactor, change of the conversion with time differed appreciably depending on the heating rate even when other operating variables were the same. With increasing heating rate the conversion during heating period decreased while the apparent reaction rate constants increased. Using the kinetic data together with the observed residence time distribution of the coal particles, the conversion in the continuous reactor was predicted. From a comparison between the predicted and the observed conversions, it is concluded that conversions in a continuous reactor can be predicted on the basis of kinetic data obtained in a batch reactor with the same heating rate.     

PYROLYSIS AND LIQUEFACTION OF BRAZILIAN COAL AND COAL-DERIVED ASPHALTENES

The present work describes a study of the liquefaction and pyrolysis of a Southern Brazilian mineral coal and its derived asphaltenes, using conversion systems developed in our laboratory.

The results show that significant quantities of the intermediate polarity fraction named resins is obtained through the pyrolysis of coal, while after the liquefaction process higher quantities of the higher fractions was found. A model is proposed to explain the liquefaction and pyrolysis processes of both coal and coal-derived asphaltenes.     

PYROLYSIS AND LIQUEFACTION OF BRAZILIAN COAL AND COAL-DERIVED ASPHALTENES

ABSTRACT

The present work describes a study of the liquefaction and pyrolysis of a Southern Brazilian mineral coal and its derived asphaltenes, using conversion systems developed in our laboratory.

The results show that significant quantities of the intermediate polarity fraction named resins is obtained through the pyrolysis of coal, while after the liquefaction process higher quantities of the higher fractions was found. A model is proposed to explain the liquefaction and pyrolysis processes of both coal and coal-derived asphaltenes.     

LIQUEFACTION AND THE CHARACTERIZATION OF COAL DERIVED LIQUIDS OF MENGEN LIGNITE

ABSTRACT

The liquefaction characteristics of Mengen lignite has been investigated in the presence of cobalt-molybdenum on alumina catalyst in a 1 lt batch autoclave system with anthracene oil used as solvent. The experiments were carried out in the range of 15–60 atm for initial hydrogen pressure, 360–440°C for reaction temperature, 1–5 for solvent to coal ratio and 0–20% of coal for catalyst loading which were chosen as process variables. Coal particle size and reaction time were kept constant as below 200 mesh and 30 minutes respectively, (Erdem 1987)

The product was analyzed in terms of total conversion, liquid yield and liquid product distribution determined as preasphaltenes, asphaltenes and oils. The oil fraction was further separated by column chromatography while the asphaltenes were separated into basic and acid/neutral fractions. The preasphaltenes were divided into two fractions as carbene (CS₂ solubles) and carboid (CS₂ insolubles). (Inanç 1989)

The oil yield is mostly affected by the catalyst loading which shows to a certain extent that the conversion of asphaltenes to oils is a catalytic step. The selected process variables showed a positive trend with respect to the yield of hexane eluted oil which is the desired product of liquefaction.     

MANAGEMENT OF COAL MACERALS IN THE LIQUEFACTION OF LOW RANK COALS

Three Alberta subbituminous coals were selected to investigate the contribution of different macerals to liquefaction. These coals represent the full range of geographic, rank and geological variations present In the Alberta Plains Coal Region. In addition, for comparison, two U.S. lignites (Texas and North Dakota) were included in these investigations. To enhance maceral concentration, density fractionation was carried out on these samples. Though liquefaction yields appear to increase with increase in vitrinite (huminite) content, a clear-cut correlation between conversion and maceral content is not established because of (a) uncertain behaviour of semi-inert macerals and (b) differences in behaviour within the vitrinite (huminite) macera1 group.     

EFFECT OF IRON CATALYST ON THE COMPOSITION OF OIL FROM COAL LIQUEFACTION

The effect of two iron catalysts, red mud and CGS S-G, as well as C0-Mo/AI₂O3 and Ni-Mo/Al₂03 commercial catalysts on the composition of oil derived from the liquefaction of Japanese subbituminous coal have been investigated comparatively by conventional autoclave experiments at 440 and 450^°C under initial hydrogen pressure of 85kg/cm² G with tetralin to coal weight ratio of 3. From the results obtained at 450^°C, total conversion and the yield of gas revealed almost same level with four catalysts, but the oil product from molybdenum catalysts showed higher yield than that from iron catalysts. CGS S-G catalyst also showed higher yield of oil product than red mud catalyst. Reaction behavior of two iron catalysts were also tested by solvent recycle mode experiments.     

MATHEMATICAL MODELLING OF THE RHEOLOGICAL PROPERTIES OF PETROLEUM BITUMENS

Three main rheological properties of petroleum bitumens were investigated with the aim of developing a suitable model for the determination of a quality parameter. Two mathematical models have been proposed; one relates softening point to penetration while the other correlates softening point and viscosity. Comparison of the two models with another previously developed model shows that the softening point/viscosity model produces the best results. It also has a great advantage since viscosity can be more accurately measured than penetration and on-line quality control can be effected through viscosity within a few seconds The results of this investigation justify the objective of finding a system of parameters relating the rheological characteristics of bitumens with the generally accepted criteria.