Solvent treatment of coals: 1. Effects on microporosity at ambient temperature

The effects of extraction with thirteen solvents and three solvent mixtures at ambient temperature on the surface areas of three bituminous coals were investigated. The total surface area of each coal, measured by CO₂ at 298 K, was substantially increased by extraction with pyridine, ethylenediamine, methylpyrrolidinone and THF. The maximum surface area attained was nearly the same for the three coals—evidence for a similar, highly crosslinked macromolecular network type of structure in all three coals. Given enough time, the mixed solvents were also effective in increasing the total surface area when the ‘solubility parameter’ of the coal was equal to the ‘solubility parameter’ of the mixture. None of the solvents increased the surface area measured by nitrogen significantly, indicating that the pores opened by the extraction of soluble pore material were < 0.5 nm in size. All the effective solvents satisfied the donor and acceptor number requirements for extraction of pore material based on the donor-acceptor model of coal extraction.     

‘Solubility parameters’ in coal and coal liquefaction products

‘Solubility parameter’ spectra have been used in polymer research to determine the characteristics of cross-linked polymer systems. Cross-linked systems are not soluble in any solvent. Instead, solvent is imbibed by the cross-linked polymer and causes it to swell. The ‘solubility parameter’ of the solvent which causes maximum swelling is identified as that of the cross-linked material. Coal can be thought of as having some characteristics of a cross-linked system^1,2. That is, when immersed in a solvent with which it interacts, it will swell. In addition, coal contains extractable material. If coal is regarded as a ‘multipolymer’, this extractable matter can be thought of as the uncross-linked portion of the coal. Swelling spectra have been taken for untreated coal and coal from which some extractable matter has been removed, which partly suppresses swelling. This extractable matter can be thought of as similar to the uncross-linked coal molecule. Its structure can therefore be used to model the coal matrix itself, to determine the coal structure without using destructive chemical methods to break the coal apart. Dissolution spectra for both the coal extract and the coal liquefaction products from the PAMCO and Synthoil processes were taken. A set of mixed solvents with effective ‘solubility parameters’ ranging from 14.3 to 47.9 MPa^1/2 (7.0 to 23.4 hildebrands) was used. The behaviours of the coal extract and coal liquid products show striking similarities, leading us to believe that molecules similar to those found in liquefaction products already exist in the virgin coal and that hydrogenation products reflect the properties of the starting material.     

Solubility enhancement of electrolyzed coal residues

Coal slurries were electrolyzed in acidic as well as basic electrolytes at different oxidizing potentials. The partially reacted coal residues were subjected to Soxhlet extraction with an equivolumetric mixture of benzene and ethanol for a period of 24 hours. The solvent-soluble organic part of coal was analyzed by GC-MS. Coal electrolyzed in acidic electrolytes became more accessible to extraction by the solvents used in the study. Electrolysis at 3.1 V vs. SCE (saturated calomel electrode) of a North Dakota lignite enhanced the solubility of coal in the benzene-ethanol mixture by a significant amount of 33%. Coal electrolysis in basic electrolytes at lower electrode potentials resulted in enhanced solubility of coal; however, at relatively large electrode potentials the yield of organic chemicals obtained by Soxhlet extraction declined.     

催化裂化（FCC）油浆作煤直接液化溶剂的研究进展

煤制油工艺等煤炭清洁高效转化技术是能源化工领域的研究热点,溶解性好、提供/传递氢能力强且热稳定性高,其溶剂选择、使用是影响煤制油工艺经济运行的关键。本文以煤液化溶剂作用为基础,通过对液化自身产物、废塑料及FCC油浆等煤直接液化溶剂的组成、性质及作用效果的综合评述,指出煤、溶剂、氢气间的混合并非理想混合,与煤H/C适宜、极性相近的溶剂在共处理过程表现出良好的协同作用,液化过程的转化率、轻质产物选择性明显提高。分析表明,协同作用的大小取决于煤、溶剂的组成、性质匹配。煤-重质烃共处理工艺利用富芳烃油浆溶解性好、提供/传递氢能力强的特点强化了煤热解加氢反应的进行,同时煤加氢液化产生的多孔残煤具有吸附性强的特点,有助于重质烃改质,使共处理转化率显著提高、轻质产物选择性增大。最后指出,煤-重质烃共处理的协同作用为改善煤、中质/重质芳烃的综合利用提供了可能。     

Solubility study for the purification of hydrogen from high pressure hydrocracker off-gas by an absorption-stripping process

Experiments were carried out to identify a solvent which has a high solubility and selectivity for methane relative to hydrogen at 295 K and pressures from 13.88 to 20.78 MPa. Binary solubilities with pure hydrogen and methane, and ternary solubilities with 73 mol% H₂ and 27 mol% CH₄ were measured at 295 K and for pressures from 6.99 to 20.78 MPa in various organic solvents. This gas mixture simulates hydrocracker and hydrotreater off-gases which are candidates for purification with an absorption-stripper. Of the solvents tested, 2,2,4-trimethylpentane (iso-octane), which showed very high methane solubility and a reasonable selectivity, and methylcyclohexane, which showed a very high selectivity and a reasonable solubility, are the best solvents for methane absorption. Correlations for hydrogen and methane as a function of pressure and solvent solubility parameter were developed with the experimental solubilities. Binary interaction parameters for Peng-Robinson (Peng and Robinson, 1976) and Soave-Redlich-Kwong (Soave, 1972) equations of state were calculated with experimental solubility results. Prediction of gas solubility in a ternary system was compared with experimental and found to be satisfactory when experimental binary interaction parameters were used.     

Alternatives to Water in Textile Processing

Attempts have been made to correlate the use of organic solvents as alternatives to water in textile processing with the ‘solubility parameter’ concept. Chlorinated hydrocarbons prove suitable for scouring and some finishing operations since their solubility parameters are ideal for such operations. In dyeing, however, the solubility parameter of polyester fibres, dyes and perchloroethylene are very similar, resulting in poor exhaustion of conventional disperse dyes. New solvent dyeing systems and new dyes, with high partition coefficients in polyester fibres, must be developed for solvent dyeing to become of practical consideration. Other solvents have been examined for solvent assisted dyeing. It has been shown that when benzyl alcohol and 2-phenoxy ethanol are used in dyebaths at concentrations at which these solvents are not completely in solution, both the rate of dyeing and penetration of dye into the fibre can be markedly increased in comparison to normal aqueous dyeing with polyester, nylon and acrylic fibres.     

Correlation and Prediction of the Solubility of CO<Subscript>2</Subscript> in a Mixture of Organic Solution Solvents

The solubility of carbon dioxide in a mixture of organic solvents was measured at atmospheric pressure in the temperature range of 10–25°C. The solubility of carbon dioxide in the mixture of organic solvents was obtained by using experimental data. In addition, the adjustable parameters of the local composition based models such as the Wilson, the NRTL, and the NRTL-NRF were determined by fitting the experimental data and the results of these models. The results show that the Wilson and the NRTL-NRF models used for the estimation of the CO2 solubility in the mixture of organic solvents used in this work attained relatively better results than the other models.__________From Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 3, 2005, pp. 259–263.Original English Text Copyright © 2005 by Pazuki, Pahlavanzadeh.This article was submitted by the authors in English.     

Swelling of coal in relation to solvent electron-donor numbers

Twenty solvents characterized by electron-donor and electron-acceptor number and solubility parameter were used to study the swelling of a hvB coal. It was found that extent of swelling could be correlated with solvent electron-donor number. Mechanisms of swelling include solvent-induced breakage of electron-donor—acceptor interactions between coal macromolecules.     

两维新溶解度参数和柴油脱蜡溶剂的选择

试图应用两维溶解度参数理论对能够改善柴油低温流动性能的脱蜡溶剂进行筛选。在建立两维平面坐标模型的基础上,计算了柴油中各组分和14种溶剂的两维溶解度参数,提出了用两维坐标图中溶剂与正构烷烃溶质的距离R_c作为是否相溶的判断依据。通过分析两维溶剂溶解度参数与萃取效果的关系,发现除2-丙醇外其他溶剂的正构烷烃萃取率随着R_c的增大而增大,表明可以依据溶剂的R_c选择柴油的脱蜡溶剂。同时发现物理溶解度参数Δ_p对溶剂的脱蜡性能影响很小,萃取过程主要受化学溶解度参数分量Δ_c的影响,且溶剂的偶极力是影响其脱蜡性能的主要因素。     

煤的溶剂萃取研究进展（I）有机溶剂及其萃取机理

讨论了煤的溶剂萃取研究现状，主要介绍单一溶剂，如四氢呋喃（THF）、环已酮（CHO）及吡啶（Py)等；混合溶剂，主要是N－甲基吡咯烷酮（NMP）混合溶剂，如CS2／NMP和CHO／NMP等的萃取性能，介绍添加剂、煤岩组成以及辅助手段等对煤溶剂萃取的影响，辅助手段主要是超声辐射、电磁辐射以及化学处理等，它们或多或少改变萃取过程，一般可使萃取率提高，同时对单一溶剂萃取机理、混合溶剂萃取机理、添加剂增溶机理以及辅助手段增溶机理等进行了讨论。研究证明，煤的有机溶剂萃取受许多因素影响，其中改变溶剂或加入一定量添加剂可以在一定程度上改变煤的溶剂萃取性能，实验条件也是一个重要的影响因素，但煤本身的问题，诸如煤的结构、煤的组成、实质程度以及煤岩组成等也会对煤的溶剂萃取性能产生重要影响。     

Prediction of gas solubility properties in binary mixtures of non-polar solvents by the empirical slopes approach

In a previous paper¹ we described how empirical slopes and parameters, derived from graphs of experimental solubility properties, could be effectively used to predict the solubility and related properties for 18 gases in 30 relatively non-polar solvents. In this paper the “empirical slopes approach” is extended to provide predictions of solubility and entropy of solution for these gases in binary mixtures of the same solvents. Predictions of solubility and entropy of solution have been calculated for several of the gas-mixture systems that have been measured experimentally and the agreement is found to be satisfactory. The merits of this approach are compared with those of other theories which can be used to yield gas solubility predictions in mixed solvents.     

Development of coal research — a review

Coal research started about 1780, but as a scientific discipline it dates from about 1830. In the ‘classical’ period of coal research its two ‘pillars’, i.e. coal petrology and coal chemistry developed to full-grown branches of science (1913–1963). After a short period of decline, coal research is now flourishing again. The main events in the 200 years history of coal research are described in this Paper. Also the sense and meaning of basic coal research, the nature of coal science as an interweaving of chemistry and physics, the position of the coal scientist in the scientific community and the relation of coal science with the Universities are discussed.     

Action of solvents on coal at low temperatures: 1. Low-rank coals

The dissolution behaviour of brown coals (67–75% C, daf) in pyridine, primary amines and aqueous KOH has been studied. The solubility in the last two solvents greatly depends on temperature, but in the first it is relatively temperature-independent. Pretreatment of the brown coals with aqueous HCl or with sodium ethanolate in ethanol leads to enhanced solubility. It is concluded that ester-bond breaking is necessary before extensive dissolution can take place. The solubility of brown coals in amines and aqueous KOH is found to increase with increasing carboxylic-acid group concentration in the coal. The solubility of Morwell brown coal in n-alkylamines at 180 °C increases with increasing length of the alkylchain in the solvent. The class of good solvents for brown coals is restricted to strong bases, because: 1. ester bonds have to be broken, 2. the acidic coal fragments have to be solubilized. Because of their capacity to break ester bonds these are so-called reactive solvents. Complete solvent recovery is impossible in the case of amines.     

The chemical modification of enzymes to enhance solubilization in organic solvents for interaction with coal

Some enzymes can effectively function as catalysts in contact with organic solvents in a variety of ways; however, it is desirable to utilize the enzyme in a soluble form for interactions with a solid substrate such as coal. Dinitrofluorobenzene (DNFB) has been used as the reagent to add dinitrophenyl groups to enzymes, thus increasing hydrophobicity and solubility (up to 20 mg ml⁻¹) in less-polar organic solvents ranging from dioxane to benzene. Mixed reducing enzymes modified by DNFB and used in pyridine or benzene under hydrogen have been shown to enhance significantly the solubility in organic solvents of coals ranging from lignite to bituminous, with up to 35.3 wt% coal conversion. A fluidized-bed bioreactor appears to be the most effective contactor.     

Solubility correlation by model with partial molar volume

Jouyban-Acree/van't Hoff model was often used to correlate solubility data, which was related to temperature, and the mole fraction of each solvent in the mixture of two solvents. In this work, the partial molar volume of each component in the mixture of two solvents was first time introduced as a modification to the Jouyban-Acree/van't Hoff model. Furthermore, machine learning and artificial intelligence (AI) technology based on temperature, mole fraction, and partial molar volume of each solvent were employed to improve the accuracy of the solubility estimation. The models were evaluated in terms of their ability to mathematically correlate solute solubility in binary solvents. An average root mean square deviation (RMSD) is used to measure the deviation between the calculated values and the experimental values. With partial molar volume as a modified parameter of the Jouyban-Acree/van't Hoff model, the overall RMSD of all the correlations of solubility improved.     

甲烷在常三柴油-四氢呋喃混合溶剂中高压溶解度的测定

为了满足富氢气氛下煤直接液化基础数据的需要,选择常三柴油、四氢呋喃为混合溶剂,利用自建的循环法气体高压溶解度测定装置,测定了甲烷在柴油-四氢呋喃中的高压溶解度数据（273.45～293.75 K,2.09～7.97 MPa）。利用n-d-M-LP法以及C-G法计算了柴油的平均结构和特性参数,利用Peng-Robinson状态方程结合两种混合规则回归实验数据,得到CH^₄-柴油-四氢呋喃的交互参数,并估算了同条件下的溶解度数据,结果表明估算值与实验值吻合较好。     

氧气(1)-乙酸(2)-水(3)三元系平衡溶解度的测定及关联

建立了测定气体在液体中溶解度的实验装置,该装置一次进料能够连续测定多种压力下的溶解度数据,并测定了25～80 ℃氧气在乙酸-水混合溶剂中的溶解度数据.建立了氧气在乙酸-水混合缔合溶剂中溶解度的计算模型,给出了模型参数,模型计算平均相对误差不超过±3.0%.     

Composition and performance of distillate recycle solvents from the SRC-I process

Recycle distillates (‘solvents’) from the Wilsonville, Alabama, SRC-I pilot plant have been analysed by a variety of methods, and the composition data related to the performance of the solvents in both batch and continuous unit coal liquefaction. Because of its low distillate yield, solvents in the SRC-I process evolve rather slowly from the ‘anthracene oil’ start-up solvent to steady-state, process-derived distillates. As the steady-state solvent evolves it increases in saturates and mono-aromatic hetero molecules (primarily phenols and indanols), and its quality as a liquefaction medium declines. Because it is low in condensed aromatics, the steady-state SRC-I solvent cannot be greatly improved by hydrogenation. Other analytical data are provided which describe the composition of SRC-I recycle distillates. The analytical methods used in this work are of adequate simplicity that they could serve as routine monitoring methods in SRC-I liquefaction.     

Effect of coal liquefaction conditions on the trace element content of the soluble non-volatile product

Analysis of 18 trace elements via inductively coupled plasma atomic emission spectrometry has been performed on ‘in-house’ coal-derived non-volatile products. Analyses were conducted in a pyridine matrix to determine the effect of various conversion parameters on metal content. Four subbituminous coals (Wyodak 1–4) and one bituminous coal (Indiana V) were employed in conjunction with both non-basic (tetralin) and basic (1,2,3,4-tetrahydroquinoline) model process solvents. Trace metal data on solvent-refined coals as a function of feed coal, process solvent, reaction time, reaction temperature and extraction solvent are reported. Few trends in metal concentration are apparent on changing various liquefaction parameters. Metal concentrations are, however, approximately one to two orders of magnitude higher in pyridine soluble SRC relative to toluene soluble SRC. The majority of soluble metals, it is therefore suggested, are in the form of coordination complexes rather than true organometallics in SRC. Information regarding the effective molecular size of metal-containing species has been obtained via size exclusion chromatography with specific metal detection. Subtle changes are observed in the effective molecular size of metal-containing materials using different liquefaction parameters. For example, a greater fraction of each metal appears to be bonded to larger ‘sized’ molecules in pyridine soluble fractions than in toluene soluble fractions.     

Investigation of wax deposit ‘sloughing’ from paraffinic mixtures in pipe flow

Deposit ‘sloughing’ from ‘waxy’ crude oils has been described in the literature as a possible mechanism, leading to partial or complete dislodging of the deposit from the pipe wall due to changes in flow parameters. A bench‐scale flow loop apparatus was used to investigate ‘sloughing’ with prepared single‐phase ‘waxy’ mixtures of a multicomponent paraffinic wax dissolved in a multicomponent solvent. Experiments were performed to study the changes in the deposit‐layer thickness due to step increments in the ‘waxy’ mixture flow rate, the mixture temperature, and the coolant temperature. It was observed that the deposit‐layer thickness decreased with an increase in each of the three parameters; however, a complete or sudden dislodging of the deposit‐layer did not occur in any of the experiments. A steady‐state heat‐transfer model was used to predict the variation in the deposit mass or thickness due to changes in the selected parameters. In each case, the step‐wise decrease in the deposit thickness, as observed experimentally, was predicted to be caused by changes in the thermal resistance and/or thermal driving force.