An important factor affecting synergism on coprocessing of Taiheiyo coal with Athabasca oil sand bitumen

A series of mixtures of Japanese subbituminous Taiheiyo coal and Athabasca oil sand bitumen (AOB) with various coal concentrations (0–100 wt%) was coprocessed in a 70 ml autoclave at 420°C for 1 h in the presence of H₂ (50 kg/cm² at room temperature) and sulfided Ni---Mo/Al₂O₂ catalyst. The mixture containing 2 wt% coal produced the largest amount of hexane soluble fraction (HS) and the smallest amount of benzene insoluble fraction (BI). Thus, a synergistic liquid production occurred for this mixture with 2 wt% coal by suppressing the retrogressive reactions which proceeded for pure AOB. The HS obtained from mixtures with 2–30 wt% showed higher H/C ratios and lower heteroatom contents than those obtained from pure AOB and the mixtures with more than 30 wt% coal. The amounts of transferable hydrogen contained in the mixtures were estimated using anthracene as a hydrogen acceptor. The mixtures with 2–10 wt% coal contained higher amounts of donor hydrogen than pure AOB. The HS yield from the various mixtures was correlated with the amount of donor hydrogens contained in the mixtures, except for the mixture with 10 wt% coal. Thus, the important factor which results in synergism is suggested to be the amount of donor hydrogens contained in the feed mixtures.     

Variation of the metal complexing ability of humic acids with coal rank

The variation of the metal complexing ability of humic acids with the rank of the parent coal was investigated by determining the conditional stability constants of complexes formed between cupric ions and humic acids from several coals. Humic acids were extracted from four Spanish coals varying in rank from peat to subbituminous coal. The stability constants were determined at pH 5.0 and μ = 0.1 by a modified version of Schubert's ion exchange method. The stability of the metal-humic acid bonds decreases with the rank of parent coal. The stoichiometry of the complexes tends to 1:1 with increasing coalification of humic acids. The influence of oxidative conditions of extraction on the conditional stability constants of complexes was also examined and it was found that they do not affect significantly the elemental composition or the metal complexing ability of regenerated humic acids.     

Non-crystalline inorganic matter-humic complexes in Athabasca oil sand and their relationship to bitumen recovery

Bitumen-free solids from different grades of Athabasca oil sand were fractionated according to particle size before and after treatment with sodium pyrophosphate (Na₄P₂O₇) solution. All solids showed decreasing amounts of organic matter from coarse to fine fractions. The concentration of organic carbon retained in all size fractions after the treatment was found to be significantly lower as compared with that before the treatment.The mineralogy and some chemical properties of the material separated as a result of treatment were investigated. The data obtained indicate that treatment releases mostly non-crystalline compounds (possibly metal oxides in some kind of association with humic matter).A cold-water agitation test (CWAT) was used to correlate bitumen recovery with the amount of inorganic matter-humic complexes separated. It was observed that most of the bitumen was liberated when inorganic matter-humic complexes could be separated during the CWAT. For some oil sands complexes could not be isolated and in these cases most of the bitumen appeared to be associated with that fraction of solids consisting of globules of fine sand and clay particles cemented together with humic matter.     

Solubilized coal as a substrate for biodesulfurization

Problem areas in a multi-step coal desulfurization process were investigated. The process involves mild hot air oxidation, followed by alkaline extraction to separate the resultant humic acid molecules from the insoluble pyrite and ash, and microbial removal of organic sulfur from the solubilized coal molecules. A computer-controlled and -monitored solubilization reactor for humic acid production was constructed. Studies designed to evaluate the physical/chemical nature and solubility characteristics of the humic acids were undertaken, with the ultimate aim of ensuring accessibility of sulfur atoms buried in the interior of these large hydrocarbon macromolecules. One per cent Tween-80 enhanced the solubility of humic acids four-fold. Radiotracer labelled humic acids containing 10.8 × 10⁻¹¹ Bq mg⁻¹ of ¹²⁵I were produced. These labelled humic acids will be used to develop an accurate and dependable assay for microbial organic desulfurization.     

Comparison of the chemical structure of coal hydrogenation products,athabasca tar sand bitumen and Green River shale oil

Coal hydrogenation products, Athabasca tar sand bitumen, and Green River shale oil produced by retorting were analyzed by the Brown—Ladner method and the Takeya et al. method on the basis of elemental analysis and ¹H-NMR data, by ¹³C-NMR spectroscopy and by FT-IR spectroscopy. Structural characteristics were compared.The results show that the chemical structure of oils from Green River shale oil and Athabasca tar sand bitumen, and the oils produced in the initial stage of hydrogenation of Taiheiyo coal and Clear Creek, Utah, coal is characterized as monomers consisting of units of one aromatic ring substituted highly with C_3–6 aliphatic chains and heteroatom-containing functional groups. The chemical structure of asphaltenes from Green River shale oil and Athabasca tar sand bitumen is characterized by oligomers consisting of units of 1–2 aromatic rings substituted highly with C_3–5 aliphatic chains and heteroatom-containing functional groups. The chemical structure of asphaltenes from coal hydrogenation is characterized by dimers and/or trimers of unit structures of 2 to 5 condensed aromatic rings, substituted moderately with C_2–5 aliphatic chains and heteroatom-containing functional groups.The close agreement between fa(¹H-NMR) and fa(¹³C-NMR) for Green River shale oil derivatives and Athabasca tar sand derivatives indicates that the assumption of 2 for the atomic H/C ratio of aliphatic structures is reasonable. For coal hydrogenation products, a value of 1.6–1.7 for the H/C ratio of aliphatic structures would be more reasonable.     

有机氮肥对马来西亚沙捞越州酸性土壤玉米干物质产量及铵态氮和硝态氮含量的影响

腐殖质中的腐植酸和黄腐酸可以提高土壤中可交换性铵（NH4＋）的回收率。这两种酸固定和保持NH4＋的能力已经在许多研究中得到了证实,二者通过提高植株的光合作用速率、促进根系发育影响植物的生长和养分吸收。因此,本研究调查了这两种酸（液态）对玉米干物质产量、土壤铵态氮和硝态氮（NO3-）含量的影响。根据液态有机氮肥的组成,采用标准方法分离提纯腐植酸。有机氮肥在玉米种植后第10天、第28天分别施入盆栽土壤,然后在种植后第54天或孕穗期采集植株和土壤样品。土壤样品分析PH、铵态氮和硝态氮含量,植株样品测定干物质产量。结果表明,在酸性条件下,液态有机氮肥（黄腐酸、腐植酸或二者同时施用）的施用可以提高土壤中NH4＋的累积量。随土壤活性碳储量的增加,腐植酸分子上羧基官能团对土壤NH4＋的吸附能力增强。然而,酸含量较低时对干物质产量的影响明显减小。各处理间硝态氮的有效性没有达到统计上的差异显著水平。较低的PH值能抑制土壤硝化作用进程,同时降低土壤NO3-含量。这表明液态腐植酸和／或黄腐酸在提高尿素利用效率方面发挥着重要作用。然而,与腐植酸分子特性有关的作用机理还需要进一步详细研究。本研究为液态和叶面有机肥料的发展提供一定的依据。     

Non-aqueous enzymatic solubilization of coal-derived materials

The utilization of enzymes in non-aqueous solvents was explored for the conversion of coal-derived materials to oil-soluble derivatives for use as fuels. A novel three-step process was developed:

1. (1) an initial low-severity conversion to a form that is soluble or dispersible in a polar solvent;

2. (2) formation of an alcohol substrate with a high activity for subsequent enzymatic processing;

3. (3) lipase-catalysed transesterification to a product that is soluble in hydrocarbon solvents.

The process was successful for the conversion of a first-stage liquefaction product from Wyodak subbituminous coal to an acylated product, about half of which is soluble in hexane and the remainder in toluene. Coals, humic acids and several other higher-molecular-weight coal liquefaction products, such as Chemcoal, and their derivatives inhibited the lipases, and thus the alcohol intermediates from these precursors were converted in 0–5% yields to acylated products.     

Short contact-time liquefaction of subbituminous coal: Directions for improving coal conversion

This study was undertaken to find ways to solubilize subbituminous coal in high yield at short contact times. Short contact-time hydroliquefaction runs were carried out in a continuous unit using Belle Ayr subbituminous coal with a solvent rich in hydrogen-donor molecules derived from the Lummus ITSL process, and also with solvents lower in donor concentration derived from the SRC processes. Catalysis by pyrite, molybdenum and supported cobalt-molybdenum was also studied. It was found that pyrite and other hydrogenation catalysts enhanced solubilization and also increased production of distillate oil. Solvent quality seemed to have no effect on the solubilization of Belle Ayr coal. The availability of H₂S also appeared to have no effect. Provided that pyrite was present, reaction could be carried out at severities high enough to give insoluble organic matter yields equivalent to those obtained with bituminous coals (5–10 wt% daf coal). At equivalent levels of solubilization, however, hydrocarbon gas and distillate yields were invariably higher for the subbituminous coal. Implications for two-stage processing of Belle Ayr coal are discussed.     

Structural changes in humic acids during the coalification process

Humic acids from four coals, varying in rank from peat to subbituminous coal, have been characterized by elemental analysis, acidic groups, molecular weight, electrophoresis and visible, FT-i.r. and CP/MAS ¹³C n.m.r. spectroscopy. The humic acids increase in carbon content, molecular weight, condensation degree and aromaticity (f_a) with increasing maturation of the parent coals, while the oxygen content decreases with a loss of oxygen functional groups. The presence of lignin-like polymers, poly-saccharides and peptidic materials in humic acids from peat was established using i.r. and ¹³C n.m.r. spectroscopy. The structural changes observed in humic acids are in agreement with the recognized coalification theory and tend to support the hypothesis of condensation of humic acids into insoluble humin of coal.     

臭氧催化氧化降解煤化工生化进水有机物的实验及机理

研究了臭氧催化氧化降解煤化工生化进水有机物的工艺条件及机理。本文以新疆某煤化工生化进水为研究对象,确定废水中难降解有机物的种类及含量,开展臭氧催化氧化试验,探讨工艺条件对化学需氧量（COD）的去除率,最后以溶解性有机物（DOM）为对象,解析废水难降解有机物的降解规律。结果表明：废水中主要为苯酚及腐殖酸;最佳工艺参数为催化剂投加量1.2L/L、臭氧浓度500mg/L、臭氧通气量2.5m³/h;反应后各组分的UV₂₅₄均下降,去除率从高到低为疏水性中性物质（HoN）>亲水性碱性物质（HiB）>疏水性碱性物质（HoB）>亲水性酸性物质（HiA）>疏水性酸性物质（HoA）>亲水性中性物质（HiN）,富里酸类、腐殖酸类、蛋白质类及溶解性生物代谢产物等荧光强度均降低。     

Occurrence and significance of humic acids in ancient sediments

Under mild conditions humic acids persist in ancient sediments (up to 70% of the total organic matter). In most samples studied, there is a relation between humic acids and associated kerogens, and this is a possible way to obtain more information on the structure of kerogens. The occurrence of humic compounds characterizes the immature stage; they rapidly disappear with natural evolution, hence the humic content would be an interesting marker of evolution during the immature stage. Moreover these compounds may be compared with humic acids occurring in recent deposits; thus they are a valuable source of information about the original organic matter and deposit media.     

Evaluation of adsorption and coagulation characteristics of humic acids preceded by alternative advanced oxidation techniques

Humic substances mainly humic acids constitute the major fraction of natural organic matter in water supplies. Humics express diverse actions primarily related to the formation of potentially harmful disinfection by products (DBPs). Therefore, the removal of DBP precursors through numerous treatment techniques gains high importance. Besides the conventional treatment processes, the applications of advanced oxidation techniques are considered as effective tools for the elimination of humic acids (HAs) from natural waters. In the present study, both the adsorption and coagulation characteristics of humic acid samples are evaluated subsequent to pretreatment by photocatalytic oxidation and ozonation. The changes in preoxidized humic acid solutions are assessed in relation to the alterations induced in the UV-vis and fluorescence spectroscopic properties. The removal efficiency of color in terms of Color₄₃₆ and aromaticity with respect to UV₂₅₄ are presented relevant to each treatment step. Major key parameters such as the selection of coagulant types (alum and ferric chloride), coagulant aids (ionic and non-ionic polyelectrolyte) and optimum coagulant dose were comparatively discussed. The adsorption characteristics of powdered activated carbon (PAC) and granular activated carbon (GAC) were investigated.     

Distribution of inorganic and organic substances in the hydrocyclone separated Slovak sub-bituminous coal

A low-rank Slovak sub-bituminous coal from the Handlová deposit was physically treated by washing in a water-only cyclone with the goal to find the separation effect for inorganic (mainly Fe-bearing minerals) and organic substances (humic acids, diterpanes). A high-quality coal product with the ash content in the dry matter of 9.02% and carbon content of C^d = 68.12% at a mass yield of 29.51% was obtained using the water-only cyclone processing. At first, the physically treated coal samples were detailed characterized by XRD, ⁵⁷Fe Mössbauer spectroscopy, FT-IR and HR-TEM. In addition to non-crystalline organic coal components, inorganic compounds belonging to silicate minerals (kaolinite, muscovite and quartz) as well as to Fe-bearing sulphide minerals (pyrite) were identified in the sub-bituminous coal by XRD. ⁵⁷Fe Mössbauer spectroscopy detected the presence of iron carbonate (siderite), iron-containing clay mineral and two sulphur-containing minerals (pyrite, jarosite) in the untreated coal. On the other hand, only one Fe-bearing mineral, (pyrite) was found in the washed coal. Effect of the physical separation is also demonstrated in FT-IR spectra, where the peak at 1040 cm⁻¹ representing the silicate component in the untreated sample is not detectable in the washed coal sample. Presence of extractive organic substances, i.e. humic acids and tetracyclic diterpane (16α(H)-phyllocladane), in the hydrocyclone products is also evidenced. It was confirmed that the isolated diterpenoic compound is attendant in the washed product with the lowest ash content and it is assimilated with the organic part of coal. Surprisingly, humic acids were found in the highest concentration in the slurry that has the highest content of ash (63.14%).     

Prediction of bitumen content in oil sand based on FT-IR measurement

FT-IR spectra of bitumen are utilized to propose simple prediction method of bitumen content in oil sand. Analysis and fractionation of Athabasca oil sand were carried out by standard method. A fraction of bitumen dissolved in tetrahydrofuran (THF) was 9.1 wt% and insoluble fraction was found as concomitantly clean clay (sand). The asphaltene fraction of oil sand was 1.42 wt%, which has higher sulfur content and lower H/C molar ratio than that of maltene. The clean clay and bitumen were used to prepare clay/bitumen composites. FT-IR spectra of different clay/bitumen composite were measured and compared. From analysis of the absorbance data, the empirical equation to predict bitumen content in oil sand was acquired using linear least square fitting. Using this equation, bitumen content of Athabasca oil sand was predicted to have a value of 10.5 wt% which is similar to 9.1 wt% of bitumen content extracted by THF solvent from oil sand.     

Evaluation of humic acid photocatalytic degradation by UV–vis and fluorescence spectroscopy

Photodegradation of humic substances causes drastic changes in the UV–vis absorption and fluorescence properties of humic acids. In this study it is intended to fulfill the lack of knowledge about the spectral changes of humic acids during photocatalytic oxidation processes and elucidate the effects observed on the molecular size distribution of humic acid focusing on their analysis by UV–vis and fluorescence spectroscopy.

As confirmed by the spectroscopic evaluation of the molecular size distribution data, photocatalytic degradation of humic acid leads to the formation of lower molecular size (small fractions) and higher UV absorbing compounds. For fractions less than 10 kDa, UV₂₅₄ absorbing moieties in treated humic acid samples become higher than that of raw humic acid designating the generation of new species during photocatalysis. UV–vis spectroscopic changes were also evaluated by the parameters relating to the concomitant removal of the total organic carbon as well as by the ratios using absorption values at discrete wavelengths. Moreover, the fluorescence spectra of treated humic acid samples show decreasing intensity profiles with increasing photocatalytic irradiation time.     

Influence of weathering process on the flotation response of coal

The floatability of a Spanish coal from a seam (Adolfa) which is simultaneously surface mined (ASM) and underground mined (AUM) has been studied. The mineral composition of AUM and ASM coal samples, as well as changes in both mineral and organic constituents due to chemical weathering, were characterized by X-ray diffraction, i.r. and Mössbauer spectroscopies and X-ray fluorescence spectrometry. The effect of pH and surface charge on the floatability of AUM and ASM samples was investigated. The formation of humic substances in the surface of ASM coal and the presence of Fe(III) species in its mineral matter, both a consequence of weathering, together with the high content of mineral impurities (especially aluminosilicates) provide an explanation for the flotation behaviour of this coal. Basic pHs that led to humic acids dissolution and to iron(III) hydroxide precipitate desorption from the surface improved ASM coal floatability up to values similar to those obtained with unoxidized AUM coal. The formation of humic acids-mineral impurities complexes at basic pHs renders clay particles hydrophobic. As a consequence, the improvement of ASM coal floatability at pHs higher than neutral was accompanied by a low ash rejection. Mineral impurities had a large influence on the surface charge of ASM coal.     

Biodesulphurized low rank coals appraisal: Initial, treated, their bitumens and solid residues

Low rank high sulphur containing Bulgarian coals are biodesulphurized on laboratory scale. Treatment of Maritza East lignites by bacteria Pseudomonas putida B2 (PP) attained 44% total desulphurization, while biodesulphurization of Bobov dol subbituminous coal by Acidothiobacillus ferrooxidans F3 (AFe) demonstrated 14%. The caloric values were slightly altered, 0.8% for lignites and 4.7% for subbituminous coal.Bitumens from the initial and biotreated coals and fractions of their neutral oils are studied. For subbituminous coal treated by AFe F3 bacteria increase in polar diterpenoids is registered by GC/MS. Concerning the set of polar diterpenoids produced during lignites treatment by PP B2 their relative contents are comparable with the ones for initial lignites. GC/MS analyses of soluble products from both coals did not give any information for sulphur containing compounds.Temperature programmed reduction coupled “on-line” with mass spectrometry (AP-TPR/MS) and its “off-line” TD-GC/MS version are used for sulphur tracking in solid residues after bitumen extraction. Quantitative interpretation of TD-GC/MS profiles revealed changes in organic sulphur compounds, elemental sulphur and SO₂.Results gave us ground to conclude that AFe F3 bacteria decrease pyritic sulphur content and slightly oxidize coal organic matter while PP B2 bacteria influence lignite organic matter and also affect pyritic sulphur.     

Identification of clay minerals in coal and wastes from main coal washery, Zonguldak, Turkey

Identification of clay minerals present in coal and washery wastes is important in cleaning fine coal by froth flotation and in flocculation and dewatering. Therefore samples of wastes from jigs and the flotation cell at the Zonguldak main coal washery were collected and analyzed petrographically for their mineral matter content and by X-ray diffraction for their clay content. The “loss on ignition” method was carried out to determine their organic carbon and carbonates. The waste samples contain 48–68% clay minerals in addition to silicates, carbonates, sulfides and coal. Three clay minerals were identified, namely illite, kaolinite and chlorite. Illite seemed to be the dominant clay mineral in washery wastes. Loss on ignition indicated high percentages of organic matter in the fine jig tailings (21%) and flotation tailings (33%). 3%–6.5% of carbonates have also been found.     

一碳化合物生物利用和转化研究进展

一碳化合物(包括CO₂、CO、甲烷、甲醇、甲酸等)来源广泛,价格低廉,并且有望通过光催化、电催化等实现绿色、可持续生产,被认为是下一代生物制造的理想原料。自然界中广泛存在多种能够天然利用一碳化合物的微生物,对这些微生物开展研究,并进行改造和利用,使其以一碳资源为原料合成能源和化学品,对于降低对传统化石资源的依赖,实现绿色、可持续发展具有重要意义。本文主要概述各种一碳化合物的原料来源,包括传统化石资源和可再生原料、一碳化合物微生物利用途径以及各种一碳利用微生物及其改造合成燃料和化学品的相关研究进展,并对近年来构建合成型一碳转化体系的相关研究进行总结,最后分析了一碳化合物生物转化面临的挑战并对未来研究方向进行展望。     

A spectroscopic investigation of the banding or lithotypes occurring in Victorian brown coal seams

Solid-state ¹³C n.m.r. and infrared spectroscopy were used to investigate the gross differences in chemical structural between the five primary lithotypes or coal bands present in Victorian brown coal seams. Examination of a series of coal lithotypes, along with their insoluble kerogen fractions, indicated significant structural variation between the light and dark samples, particularly in their aromaticities and levels of lignin-derived structures. Comparison of K₂₉₂₀ (cm mg⁻¹) and K₁₇₁₀ (cm mg⁻¹) infrared data revealed that the aliphatic C-H content did not exhibit the level of lithotype dependence shown by carbonyl/carboxyl concentration. Correlation with ¹³C n.m.r. data revealed a direct inverse relation between aromaticity and carbonyl/carboxyl content. Aromaticity and carbonyl/carboxyl content are suggested to be the main gross chemical structural properties affecting lithotype classification. Investigation of a depth profile of the light lithotype revealed that gross structural variation between the samples did not result from rank effects. Rather, the depth profile reflects minor depositional variations which did not affect their lithotype classification. The gross chemical characterization of the lithotypes supports paleobotanical interpretation regarding the different depositional environments and inputs responsible for the observed coal banding.