Sorptional tar removal from water and solutions

Packed equipment for removing tar from water by filtration, adsorption, and coalescence is tested.     

压力对溶剂法脱除焦油沥青中固体颗粒物的影响

精制沥青是制备各种功能炭材料的前体,焦油沥青需要预处理脱除其中的固体颗粒物（称为喹啉不溶物,QI）以得到精制沥青,压力是脱除QI的重要条件。本文以煤焦油沥青和添加生物质沥青的混合沥青为原料,研究压力对溶剂法脱除固体颗粒物的影响,测试不同压力下精制沥青的QI含量及产率,利用纳米粒度分析仪、扫描电子显微镜和高温黏度测定仪对QI颗粒形貌、粒度及脱除体系黏度进行表征和测定,分析压力对固体颗粒物絮凝沉降的影响规律。研究结果表明,增加压力对沥青收率升高有明显影响,使精制煤焦油沥青的收率由常压的64.6%（质量分数）提升至1MPa时的84.3%（质量分数）,精制沥青的QI含量维持在0.06%~0.1%（质量分数）之间。添加15%生物质沥青的混合沥青,产率则由常压时的55.7%（质量分数）提升至1MPa时的72.5%（质量分数）。压力对精制沥青的QI含量影响较小,压力增大,溶剂对沥青组分尤其是重质组分的溶解能力增强,使精制沥青产率升高。较高压力也使体系的黏度略微增大,造成部分QI颗粒沉降困难,不过影响较小。中间相沥青制备的结果表明,精制沥青可以制备出具有流域型结构的中间相沥青,添加生物质沥青更好地改进了流域型的显微结构。     

Cryogenic recovery of tar from athabasca tar sands

Cryogenic recovery of tar from Athabasca tar sand could be an attractive alternative to the conventional hot water separation process. It is based on the fact that when frozen tar sand is ground, distinct particles of tar and sand are obtained and can be separated by elutriation. A specially designed fluidized bed grinder was developed for operation at temperatures in the range ?30 to ?130°C. Preliminary experiments have shown that 88% of the tar can be removed from the sand. Improved results can be expected after further optimization of the unit.     

Analysis of hydrogen-influence on tar removal by partial oxidation

In order to grasp tar reduction by partial producer gas oxidation, a two-step model is developed for computations on the chemical kinetics of partial oxidation. Free radical concentrations, and their residence times during partial oxidation are studied as a function of the gas hydrogen concentration. The computed free radical concentrations show to increase by an order of magnitude, and the residence times by three orders of magnitude, by increasing the producer gas hydrogen content. Further computations show that the concentrations and length of formed carbon containing molecules are largely independent of gas hydrogen content or air-excess ratio, but highly dependent on the gas C/O-ratio.     

基于COSMO-RS方法筛选离子液体用于焦油脱除

焦油的脱除是生物质气化规模化应用的难题。离子液体具有饱和蒸气压低、分子结构可设计等优势,在催化和吸收领域有广泛的应用前景,但在脱除焦油方面鲜有探索。以改进的COSMO-RS方法为基础,借助COSMOtherm软件推算离子液体对苯、甲苯、苯酚和萘等焦油模拟物的无限稀释活度系数。并进一步通过偏摩尔过量焓验证以上筛选结果。结果表明,优选的两取代基咪唑类离子液体对四种焦油模拟物的无限稀释活度系数值主要分布在0.4~1之间,预计具有良好的吸收性能。当阴离子相同时,两取代基咪唑阳离子随着R₁位置烷基侧链的增长吸收性能变好,其中[C₈MIM][NTf₂]表现出了较佳性能,吸收苯、甲苯和萘的γ^∞分别为0.95、1.24和1.36,但此时离子液体黏度较大;对于苯酚体系,[BF₄]^-阴离子性能较佳。     

Zirconia: Selective oxidation catalyst for removal of tar and ammonia from biomass gasification gas

Catalysts containing zirconia and alumina were tested for their activity in the selective oxidation of tar and ammonia in biomass gasification gas. Their performance was compared with that of nickel and dolomite catalysts. Synthetic gasification gas with toluene as tar model compound was used as feed. In the presence of oxygen, zirconia and alumina-doped zirconia gave high toluene and ammonia conversions even below 600 °C. They were the most active catalysts for toluene oxidation below 700 °C and for ammonia oxidation below 650 °C. At higher temperatures than these, the impregnated ZrO₂/Al₂O₃ catalysts performed better: oxidation selectivity was improved and toluene and ammonia conversions were higher. The presence of both zirconia and alumina in the catalyst promoted toluene and ammonia conversions at low temperatures: zirconia enhanced the oxidation activity, while alumina improved the oxidation selectivity. The presence of H₂S had little effect on the activity of alumina-doped zirconia.     

Pretreated olivine as tar removal catalyst for biomass gasifiers: investigation using naphthalene as model biomass tar

Biomass is considered as a potential source of renewable energy. One of the major problems for biomass gasification is the presence of tar in the product gas. We are investigating catalytic behaviour of olivine as a prospective bed additive for biomass gasifiers for tar removal. In the present paper, the pretreatment of olivine is investigated to improve its activity. Pretreatment method includes heating olivine at 900 °C in the presence of air for different treatment times. The catalytic activity of olivine is investigated via steam-reforming reaction of naphthalene as model biomass tar compound. Improvement in naphthalene conversion of around 30% is observed with 1 h of pretreatment. Also effect of pretreatment time is investigated. With increasing pretreatment time, conversion increases; more than 80% naphthalene conversion is observed with 10 h of pretreatment time for olivine. Both steam and dry reforming reaction of naphthalene forms more than 50% gaseous products over 10 h pretreated olivine. Besides the gaseous products and light tars, polymerization reactions occur producing higher tars in small quantity. Naphthalene conversion under syngas mixture is somewhat lower than that of only in steam and CO₂. Apparent activation energy of 187 kJ mol⁻¹ is determined for 10 h pretreated olivine under gasification-gas mixture.     

基于回收理念的生物质燃气焦油脱除研究进展

生物质气化是重要的可再生能源方式。焦油是生物质气化过程大规模工业化的主要障碍之一。为了提高生物质燃气用于内燃机和燃气轮机发电以及甲醇合成的效率,燃气中的焦油必须深度脱除至低于20 mg/m3。本文简述了焦油污染和堵塞燃气下游设备的危害,介绍了焦油的特征和分类,分析了基于回收过程的焦油脱除方法优势,评述了回收法焦油脱除的研究进展,阐述了水洗和油洗回收脱焦的典型应用实例。指出了以油洗回收法为基础,将焦油和微孔材料的孔径进行匹配,高集成度的吸附和膜分离多级耦合焦油深度脱除工艺,将成为脱除生物质燃气焦油的主要发展方向。     

Ampholytes from shale tar

An ampholyte with an exchange capacity of 3.9 or 7.6 mg-equiv/g for 0.1 N HCl or 0.1 N NaOH, respectively, was prepared based on a weakly basic anion exchanger from the polycondensate of shale tar by the radiation grafting of acrylic acid.     

Extraction of tar acids from tar oils by aqueous acetamide

Aqueous acetamide has been found to be a good solvent for the extraction of tar acids from low temperature carbonisation tar oils. Saturated acetamide solution at 15–30° in the molar ratio acetamide/tar acids of 3 : 1 effects a recovery of about 90% of tar acids originally present in the oil in two extraction stages. The tar acids are obtained in 77% purity, the impurities consisting of neutral oils and tar bases. Re-extraction with light petroleum can raise the purity of tar acids to 94%. Tar acids can be separated from the purified acetamide extract by suitable dilution with water. The system tar acids—(bases + neutral oils)—saturated aqueous acetamide has been studied. It has been shown that three theoretical counter-current extraction stages are required to effect a recovery of 95% of tar acids from a feed oil containing 45% tar acids. 98% recovery of the tar acids could be achieved in four stages.     

煤焦油中脱除喹啉不溶物技术的研究进展

煤焦油是一种制备高附加值碳材料的理想原料,然而其深加工利用受到内部高含量喹啉不溶物(QI)的影响。为此,本文介绍了煤焦油的组成和性质,简述了煤焦油中QI的组成、来源和其对煤焦油加工利用的危害,综合对比分析了煤焦油净化分离常用的几种方法。热过滤法分离效率虽然满足工业需求,但工业成本较高;重力沉降法操作简单,但分离效率低;离心分离法分离效率高,但处理量小,难以满足工业化应用;蒸馏处理法分离效率高,但原料利用率低;溶剂萃取法容易操作,但溶剂需求量大;改质法效果明显,但成本较高;静电分离法能量消耗低,但静电分离最佳条件变动性较大;联合处理法分离效率较高,应用前景广阔,可以作为一种净化分离的科学有效方法,并可以作为一种净化分离技术的发展趋势。     

Performance of a catalytically activated ceramic hot gas filter for catalytic tar removal from biomass gasification gas

Silicon carbide-based filter elements were catalytically activated to provide filter elements for catalytic tar removal from biomass-derived syngas. The filter element support was coated with CeO₂, CaO–Al₂O₃ and MgO with a specific surface of 7.4, 15.9 and 21.9 m²/g synthesized by exo-templating with activated carbon. Doping of a MgO coated filter element with 60 wt% NiO has led to an increase of the specific surface from 0.15 to 0.21 m²/g, whereas in case of a MgO–Al₂O₃ coated filter element a decrease from 1.18 to 0.91 m²/g was found. An increase of the NiO loading from 6 to 60 wt% on a MgO coated filter element resulted in an increase of the naphthalene conversion from 91 to 100% at 800 °C and a face velocity of 2.5 cm/s at a naphthalene concentration of 5 g/Nm³ in model biomass gasification gas. In case of a MgO–Al₂O₃ coated filter element with 60 wt% NiO in addition to complete naphthalene conversion in the absence of H₂S, a higher conversion of 66% was found in the presence of 100 ppmv H₂S compared to 49% of the MgO–NiO coated filter element. After scaling up of the catalytic activation procedure to a 1520 mm long filter candle, which shows an acceptable differential pressure of 54.9 mbar, 58 and 97% naphthalene conversion was achieved in the presence and absence of H₂S, respectively. The calculated WHSV value of 209.6 Nm³ h⁻¹ kg⁻¹ indicates the technical feasibility of a further increase of the catalytic performance by an increase of the NiO loading.     

Anion exchangers from shale tar

A weakly basic anion exchanger with an exchange capacity of 6.50 mg-equiv/g was prepared based on the polycondensate of shale tar with hexamethylenetetramine. This anion exchanger exhibited high performance characteristics such as relative rate of ion exchange and high mechanical strength; it can be used as an industrial ion exchanger for the preliminary purification of strongly contaminated media in the same areas where the commercial anion exchanger AN-2F is used.     

Development of Ni catalysts for tar removal by steam gasification of biomass

Catalytic performance of Ni/CeO₂/Al₂O₃ catalysts prepared by a co-impregnation and a sequential impregnation method in steam gasification of real biomass (cedar wood) was investigated. Especially, Ni/CeO₂/Al₂O₃ catalysts prepared by the co-impregnation method exhibited higher performance than Ni/Al₂O₃ and Ni/CeO₂/Al₂O₃ prepared by the sequential impregnation method, and the catalysts gave lower yields of coke and tar, and higher yields of gaseous products. The Ni/CeO₂/Al₂O₃ catalysts were characterized by thermogravimetric analysis, temperature-programmed reduction with H₂, transmission electron microscopy and extended X-ray absorption fine structure, and the results suggested that the interaction between Ni and CeO₂ became stronger by the co-impregnation method than that by sequential method. Judging from both results of catalytic performance and catalyst characterization, it is found that the intimate interaction between Ni and CeO₂ can play very important role on the steam gasification of biomass.     

Development of Ni catalysts for tar removal by steam gasification of biomass

Catalytic performance of Ni/CeO₂/Al₂O₃ catalysts prepared by a co-impregnation and a sequential impregnation method in steam gasification of real biomass (cedar wood) was investigated. Especially, Ni/CeO₂/Al₂O₃ catalysts prepared by the co-impregnation method exhibited higher performance than Ni/Al₂O₃ and Ni/CeO₂/Al₂O₃ prepared by the sequential impregnation method, and the catalysts gave lower yields of coke and tar, and higher yields of gaseous products. The Ni/CeO₂/Al₂O₃ catalysts were characterized by thermogravimetric analysis, temperature-programmed reduction with H₂, transmission electron microscopy and extended X-ray absorption fine structure, and the results suggested that the interaction between Ni and CeO₂ became stronger by the co-impregnation method than that by sequential method. Judging from both results of catalytic performance and catalyst characterization, it is found that the intimate interaction between Ni and CeO₂ can play very important role on the steam gasification of biomass.     

Recent advances in catalysts for hot-gas removal of tar and NH3 from biomass gasification

Biomass gasification produces a low to medium-BTU product gas (or syngas) containing primarily CO₂, H₂, CO, CH₄ and (C₂ + C₃), as well as some contaminants such as tars, NH₃, H₂S and SO₂. In order to achieve better efficiencies of the syngas applications, these contaminants must be removed before the syngas is used for internal combustion, gas engines, and in particular for fuel cells and methanol synthesis. Compared with the wet scrubbing technology, hot-gas cleanup technology to remove tar, ammonia and other contaminants at the “hot” state is more advantageous with respect to energy efficiencies. This paper provides an overview on recent advances in catalysts for hot-gas removal of tar and ammonia from biomass gasification. The review focuses on the recent development and applications of dolomite catalysts, iron-based catalysts, nickel and other metal supported catalysts, and the novel carbon-supported catalysts for hot-gas tar removal and ammonia decomposition. The barriers in applications of hot-gas cleanup processes and catalysts for full-scale biomass gasification, and areas for future research, are also discussed.     

外加剂对煤焦油无机微粒去除率的影响研究

煤焦油作为煤炭加工的副产品,是重要的化工原料,应用价值广泛,但煤焦油的净化是煤焦油深加工的前提,因此通过研究添加外加剂的除杂方法对煤焦油灰分含量的影响;结果表明,经过上述方法处理灰分含量可降至0．00449％。反应的最佳条件为：采用V水：V硫酸=20的稀硫酸的添加量为6mL,反应时间为60min;采用V水：V氨水=3的稀氨水的添加量为40mL,反应时间为20h。     

Phenolic foams from wood tar resols

This article investigates resole‐type phenolic foams, in which 40% phenol was substituted with distilled oily fractions from wood tar. Different proportions of blowing agent, hexamethylenetetramine, and stabilizer, a sodium alkyl sulfate surface active agent, were used to produce a series of rigid foams, which were characterized by curing index, density and hardness. The average curing index was about 90% and densities ranged from 480 to 960 kg.m^?3. A fractal dimension (D_f) approach was used to assess the homogeneity of pores within the foams and an average (dimensionless) value of 2.6 was found, indicating a non uniform structure. Compressive strength tests of the foams gave values above 1.0 MPa, which is higher than those for typical phenolic foams. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

溶剂效应对脱除煤沥青中3,4-苯并芘的影响

研究了单种溶剂、混合溶剂对3,4-苯并芘的溶解选择性及煤沥青溶解量。并以顺丁烯二酸酐为改性剂、硫酸为催化剂,考察了溶剂效应对降低煤沥青中3,4-苯并芘的影响。研究表明,环己烷、甲苯,环己烷、乙酸丁酯组成的混合溶剂具有较好的3,4-苯并芘溶解选择性和合适的煤沥青溶解量。当环己烷∶甲苯=2∶1（体积比）和环己烷∶乙酸丁酯=2∶1（体积比）为反应溶剂时,能够高效地脱除煤沥青中3,4-苯并芘,煤沥青中3,4-苯并芘降低率分别达到88.26%和90.83%。其原因认为是此类溶剂能使包裹在沥青颗粒内部的3,4-苯并芘释放出来,且3,4-苯并芘与改性剂能够形成均相反应体系,大部分不具有致癌性的高相对分子质量环芳烃与改性剂之间形成两相体系,从而提高了改性剂与3,4-苯并芘的有效反应。     

Producing lignite pitch from high-boiling semicoking tar

The heat treatment of high-boiling tar fractions from Berezovsk lignite (Kansk–Achinsk Basin) in a solid-fuel reactor to obtain lignite pitch is investigated. In addition, the use of the semicoke to reduce granulated phosphorus pellets from Dzhanatas ore is studied. The lignite pitch and semicoke may also be used in coking batch for the production of blast-furnace coke with improved properties; as binder in the production of domestic lignite-based fuel briquets; as binder in the sintering of Kovdorsk and Olenegorsk iron-ore concentrates at AO Severstal’; as binder in the production of anode masses for aluminum production; as binder in bricks and cold packing employed in the manufacture and sealing of electrolyzer hearths; and for pyrolysis with natural methane to increase the yield of ethylene.