Production and fuel properties of fast pyrolysis oil/bio-diesel blends

This paper describes the production and fuel properties of fast pyrolysis oil/bio-diesel blends. The bio-oils used in this study were produced from the fast pyrolysis of woody biomasses, oil mallee and pine. The bio-diesel employed was derived from canola vegetable oil. The conditions used to prepare the bio-oil/bio-diesel blends, as well as some of the fuel properties of the resulting bio-diesel rich phase, are reported. The experimental results show that the solubility of fast pyrolysis oils in bio-diesel is not as high as was previously reported for decanted oils obtained by Auger pyrolysis. The carboxylic acids, mono-phenols, furans and lignin derived oligomers were the compounds most soluble in bio-diesel, while the sugars, on the other hand, showed poor solubility. Although the presence of phenols enhances the oxidation stability of the bio-diesel rich phases, other fuel properties deteriorate. For example, the content of solid residues increased primarily because of the solubilisation of lignin derived oligomers, which were quantified by UV-fluorescence. Concentrations as high as 3.5 mass % of these compounds were observed in the bio-diesel rich phase. The solubility of bio-oil in bio-diesel was enhanced by using ethyl acetate/bio-diesel blends. Some fuel properties of the bio-diesel rich phase, after the removal of ethyl acetate, are reported.     

Catalytic pyrolysis of biomass in inert and steam atmospheres

The objective of this study was to investigate thermal conversion of a perennial shrub, Euphorbia rigida biomass sample with catalyst in inert (N₂) and steam atmospheres. Experimental studies were conducted in a well swept fixed bed reactor with a heating rate of 7 °C/min to a final pyrolysis temperature of 550 °C and with a mean particle size of 0.55 mm in order to determine the effect of different atmospheres with various catalyst ratios on pyrolysis yields and characteristics. The catalyst ratios were 5%, 10% and 20% (w/w) under nitrogen atmosphere with flow rates of 50, 100, 200 and 400 cm³/min and steam atmosphere with well-swept velocities of 12, 25 and 52 cm³/min. The optimum oil yield was obtained as 32.1% at the nitrogen flow rate of 200 cm³/min, while it was obtained as 38.6% at steam flow rate of 25 cm³/min when a 10% catalyst by weight according to the biomass was used. Higher oil yields were observed when biomass sample was treated in steam atmosphere than in inert (N₂) atmosphere. The oil composition was then analysed by elemental analyses techniques such as IR and GC-MS. The oil products were also fractionated by column chromatography. The bio-oils obtained at both atmospheres contain mainly n-alkanes and alkenes, aromatic compounds; mainly benzene and derivatives and PAHs, nitrogenated compounds and ketones, carboxylic acids, aldehydes, phenols and triterpenoid compounds. More oxygenated compounds and less substituted alkanes and alkenes were obtained in catalytic pyrolysis of E. rigida in the steam atmosphere. The experimental and chemical characterisation results showed that the oil obtained from perennial shrub, E. rigida can be used as a potential source of renewable fuel and chemical feedstock.     

Steam gasification reactivity of char from rapid pyrolysis of bio-oil/char slurry

A slurry of bio-oil and char originating from wood pyrolysis is a promising gasifier feed-stock because of its high energy density. When such a slurry is injected into a high temperature gasifier it undergoes a rapid pyrolysis yielding a char which then reacts with steam. The char produced by pyrolysis of an 80 wt% bio-oil/20 wt% char mixture at heating rates of 100-10,000 °C/s was subjected to steam gasification in a thermogravimetric analyzer. The original wood char from the bio-oil production was also tested. Gasification was conducted with 10-50 mol% steam at temperatures from 800 to 1200 °C. Reactivity of the slurry chars increased with pyrolysis heating rate, but was lower than that of the original chars. Kinetic parameters were established for a power-law rate model of the steam-char reaction, and compared to values from the literature. At temperatures over 1000 °C, the gasification rates appeared to be affected by diffusional resistance.     

Devolatilization in the temperature range 300-600 K of liquids derived from wood pyrolysis and gasification

A thermogravimetric system, previously developed for solid fuel degradation, has been modified to examine liquids obtained from conventional pyrolysis and updraft gasification of beech wood. Thermogravimetric curves in air show two main reaction stages. The first (temperatures ≤600 K) concerns evaporation, formation and release of gases and formation of secondary char (coke). Then, at higher temperatures, heterogeneous combustion of secondary char takes place. A reliable procedure has been developed to carry out the first stage under assigned temperature using a PID controller and the applied heat flux as the manipulated variable. It has been found that the pyrolysis temperature does not affect significantly weight loss dynamics and amount of secondary char (approximately equal to 20% of the liquid on a dry basis). The thermogravimetric curves are well predicted by a global mechanism consisting of three parallel first-order reactions (activation energies of 66, 32 and 36 kJ/mol, respectively). Due to strong physico-chemical transformations (sample swelling and solidification) associated with secondary char formation, it is not possible to avoid ignition during heterogeneous combustion. Therefore, this reaction stage should be investigated separately after collection and adequate re-preparation of the charred sample.     

Mallee wood fast pyrolysis: Effects of alkali and alkaline earth metallic species on the yield and composition of bio-oil

The purpose of this study was to investigate the effects of inorganic species in biomass, especially the alkali and alkaline earth metallic (AAEM) species (K, Na, Mg and Ca), on the yield and properties of bio-oil from the pyrolysis of biomass. A mallee wood sample from Western Australia was washed with water and a dilute acid solution to remove its AAEM species. The water-washed and acid-washed mallee wood samples were then pyrolysed in a fluidised-bed reactor at 500 °C under fast heating rate conditions. The removal of AAEM species did not result in significant changes in the yields of bio-oil and bio-char. However, the bio-oil properties, e.g. viscosity, were drastically affected by the removal of AAEM species. Our results indicate that the water-soluble AAEM species were not as important as the water-insoluble but acid-soluble AAEM species in influencing the bio-oil composition and properties. It is believed that the acid-soluble AAEM species (especially Ca) were more closely linked with the organic matter in biomass and thus were closely involved in the reactions during pyrolysis. The removal of AAEM species, especially the acid-soluble AAEM species, led to very significant increases in the yields of sugars and lignin-derived oligomers, accompanied by decreases in the yields of water and light organic compounds in the bio-oil.     

Hollow porous carbon microspheres obtained by the pyrolysis of TiO2/poly(furfuryl alcohol) composite precursors

Disordered carbon materials with high porosity were prepared through the pyrolysis of TiO₂/poly(furfuryl alcohol) composites, obtained by the sol-gel method. The composites were prepared starting from titanium tetra-isopropoxide (TTIP) and furfuryl alcohol (FA) as precursors. Two different synthetic procedures for our composites were carried out, based on the addition of furfuryl alcohol (FA) before or after the TiO₂ nanoparticles formation. Also, different TTIP/FA ratio was tested. The hybrid materials obtained by both synthetic routes were pyrolyzed, under argon flow, at 900 °C producing novel TiO₂/carbon composites. All samples were characterized by XRD, FT-IR, DR-FTIR, Raman spectroscopy and TEM. Results indicated the effective FA polymerization on TiO₂ (anatase) nanoparticles, and polymer conversion to disordered carbon after the pyrolysis, simultaneously with TiO₂ anatase-rutile phase transition. The resulting TiO₂/carbon composites were treated with HF solution aiming the oxide dissolution, yielding an extremely porous carbon material as insoluble fraction. The morphology of these porous carbon materials is strongly dependent on the synthetic route adopted for the composite precursor, varying from carbon foam to highly ordered hollow microspheres.     

Recycling poly-(methyl methacrylate) by pyrolysis in a conical spouted bed reactor

The pyrolysis of poly-(methyl methacrylate) (PMMA) has been studied in a pyrolysis plant provided with a conical spouted bed reactor. This reactor is an interesting technology for the pyrolysis of waste plastics due to its excellent hydrodynamic behaviour and its high heat transfer and versatility. A previous kinetic study was carried out in thermobalance, in which the degradation of this polymer was observed to begin at low temperatures, 553 K. Consequently, the activation energy is low compared to other plastics. The influence of temperature on pyrolysis product distribution in the conical spouted bed reactor has been studied in the 673–823 K range. The products obtained at low temperatures are mainly the monomers of the polymer used for the study methyl methacrylate (MMA) and ethyl acrylate (EA). When the pyrolysis temperature is increased, the yield of monomers is lower due to the higher severity of secondary reactions, and there is a significant increase in the yield of gases. The maximum monomer recovery has been obtained at 673 K, with the yields of MMA and EA being 86.5% and 6.2%, respectively.     

废塑料制取液体燃料试验研究

利用热解法将废塑料制成高品质液体燃料是资源回收和避免二次污染的重要途径。为此,设计了一套连续给料的鼓泡流化床反应器,对废塑料在鼓泡流化床中热解的关键工艺参数进行了试验研究。通过对试验数据的分析,得到了热解温度对液体产率的影响规律、气体产物的主要成分及其所占份额,并计算了废塑料热解过程的能量收支关系,为废塑料制取液体燃料的工业装置的设计、运行提供了理论及试验依据。     

A dense amorphous SiBCN(O) ceramic prepared by simultaneous pyrolysis of organics and inorganics

Utilizing active function groups and radicals of polymers (polycarbosilane) to react with a mixture of organics (urea) and inorganics(boric acid) during polymer to ceramic conversion process, a novel SiBCN(O) ceramic was successfully prepared via hot-pressing from 380 to 700 °C combined with following pyrolysis at 1400 °C for 2 h in nitrogen atmosphere. The prepared SiBCN(O) ceramic with a low open porosity of ~4%, which maintained amorphous structure still. Experimental results confirmed that the inorganic network of SiBCN(O) amorphous ceramic was constructed by Si–C, Si–N, Si–O, B–N, and B–O bonds. Pyrolysis product BN served as active filler in densification process of the SiBCN(O) ceramic. Additionally, the introduced oxygen from boric acid could be well controlled and thus effectively improved the densification process of the ceramic.     

Py-GC/MS研究防焦剂CTP的热裂解行为

采用裂解气相色谱/质谱联用法对防焦剂CTP的热裂解行为进行研究,并对部分热裂解产物的质谱碎裂机理进行探讨。结果表明：防焦剂CTP热裂解适宜条件为：温度　300 ℃,时间　0.2 min,方式　单纯瞬间裂解,固体样品直接进样;不同产地产品的裂解产物具有一致性,热稳定性好;裂解产物共10余个,主峰为原分子,次强峰为邻苯二甲酰亚胺。解析了NIST谱库中不包含的主要裂解产物可能的质谱裂解途径;可根据其中环己硫醇、邻苯二甲酰亚胺、二环己基二硫化物3个裂解产物共同判断防焦剂CTP的存在。     

Up-scalable preparation of nano zirconium carbide powder in liquid polymeric precursor and its pyrolysis mechanism

Nano size ZrC powder was prepared by liquid polymeric precursor method. Zirconium n-butoxide (Zr(OⁿBu)₄) and benzoylacetone (BA) were mixed directly with different molar ratios to synthesize transparent liquid zirconium carbide single-source precursors. The carbon content in the precursor could be changed by adding different amount of BA. X-ray pure ZrC was obtained when the molar ratio of BA/Zr(OⁿBu)₄ was 4.6:1. The viscosity of the precursor was very low (<8 mPa s) without the addition of solvents. Zirconium carbide powders were fabricated by the pyrolysis at 800 °C in argon and subsequent heating at various temperatures in vacuum for carbothermal reduction reaction. The pyrolysis behavior, phase composition and transformation, and microstructure of the as-fabricated ZrC powders were analyzed. The gases of CH₄, CO and CO₂ released due to decomposition and evaporation of the organic component and transformation from ZrO₂ to ZrC during pyrolysis resulted in total 60–70% mass loss. The average grain size of the synthesized X-ray pure ZrC powders was less than 30 nm. Meanwhile, the pyrolysis mechanism of nano zirconium carbide powder was deduced.     

木质纤维素基平台化合物催化转化制备液体燃料及燃料添加剂

随着不可再生的石化资源的不断消耗以及生态环境的不断恶化,可再生资源和能源的开发和利用受到越来越多的重视。木质纤维素是地球上最丰富的可再生生物质资源,蕴藏量和产量巨大,具有广阔的开发利用前景。本文在介绍国内外木质纤维素资源开发利用研究的基础上,结合当今世界生物质能领域的研发现状,分别概述了经由呋喃类化合物及乙酰丙酸等木质纤维素基平台化合物分子,制备液体燃料和燃料添加剂的最新研究进展。在总结归纳合成途径的同时,分析了现阶段面临的主要问题及可能的解决办法,以期能为木质纤维素类生物质能源化利用的研究提供有益的参考与借鉴。     

Formation of NOx precursors during wheat straw pyrolysis and gasification with O2 and CO2

The release behavior tests of NO_x precursors from wheat straw during pyrolysis in argon and gasification in 5%O₂/95%Ar and 5%CO₂/95%Ar were performed using a thermogravimetric analyzer (TGA) coupled with a Fourier transform infrared (FTIR) spectrometer. The results show that heating rate and particle size have substantial effects on the selectivity of N-conversion due to the selectivity of cracking of cyclic amides and the secondary reaction influencing the formation of NH₃, HCN and HNCO. The atmosphere influences the N-selectivity to HCN, NH₃, NO and HNCO. The formation of HCN and NH₃ in 5%O₂/95%Ar is a result of competition among the opposing effects of O₂. The presence of O₂ promotes the yields of HCN and HNCO evidently, and HNCO seems to be a favourable product from biomass-N compared in Ar atmosphere although HCN yield is a little bigger than that of HNCO. The use of CO₂ reduces the formation of HCN, the yield of NH₃ keeps essentially constant compared in Ar, and the emission of HNCO is suppressed. NH₃ seems to be a favourable product from biomass-N in 5%CO₂/95%Ar.     

TG-FTIR联用研究半纤维素的热裂解特性

利用FT-IR、离子色谱、1H-NMR及13C NMR等手段对蔗渣半纤维素的化学结构进行了表征,并利用热重-傅里叶红外光谱（TG-FTIR）联用技术对蔗渣半纤维素在不同的升温速率下的热失重行为进行了研究。结果表明,蔗渣半纤维素主要由大量的阿拉伯糖木聚糖组成,此外还含有葡萄糖、半乳糖及葡萄糖醛酸和半乳糖醛酸,具有草类原料中典型的半纤维素结构。蔗渣半纤维素的主要热失重区间为200～315 ℃,并在230 ℃左右出现一个肩状峰,在700 ℃时焦炭残留物比例较高,约在20%。采用一级四段模型对半纤维素的热裂解过程进行了模拟,得到各段的活化能分别为118 kJ/mol、50 kJ/mol、144 kJ/mol和34 kJ/mol。蔗渣半纤维素热解气体析出过程复杂,初期先析出游离水,随后发生解聚和脱水反应,主要的苷键和碳碳键断开形成各种烃类、醇类、醛类和酸类等物质,这些大分子物质又裂解为CO2、CO等小分子气体。在线红外分析结果表明,蔗渣半纤维素热解气态产物主要有H2O、CO2、CO和CH4和其它产物。     

Characterization of the liquid and solid products obtained from the oxidative pyrolysis of meat and bone meal in a pilot-scale fluidised bed plant

Pyrolysis of meat and bone meal material has been studied in an auto-thermal pilot scale unit with a fluidised bed reactor based on Bioware Technology. The heating value of the bio-oil samples is around 33-36 MJ/kg, whilst the nitrogen content is between 7.3 wt.% and 9.0 wt.%. Liquid fractionation with solvents of the bio-oil has been carried out. Chemical analyses of the fractions have shown that the main components in the bio-oil samples are alkanes, alkenes, oxygenated components (as alcohols) and nitrogen compounds (as nitriles) which are identified in the water insoluble fraction. Knowing the chemical composition of the bio-oils is important for assessing possible chemical and pharmaceutical applications of these bio-oils. The char samples have a notable ash content (63 wt.% to 77 wt.%) and its high Ca content could make it suitable for use as a catalyst in gasification processes.     

Changes in the cross-link density of Goynuk oil shale (Turkey) on pyrolysis

The effect of temperature and heating rate on the cross-link density of char samples obtained by pyrolysing Goynuk oil shale was investigated using the volumetric solvent swelling technique. The cross-link density decreases slightly with increasing pyrolysis temperature. The heating rate and thus the pyrolysis time had at most a small effect on the cross-link density. Char-solvent interactions do not follow regular solution theory. The demineralized kerogen swells more than does the native kerogen (16% ash).     

Boron nitride by pyrolysis of the melt-processable poly[tris(methylamino)borane]: Structure, composition and oxidation resistance

Evolution of structure and composition of the melt-processable poly[tris(methylamino)borane] (PTMB) during its conversion to ceramics was studied by TGA, FTIR, Raman, XRD, XPS and elemental analysis (EA). The results show that the ceramic yield was greatly improved from 60.22 to 74.4 wt% at 900 °C by curing in NH₃ prior to pyrolysis. The carbon impurity in the precursor can be removed effectively in NH₃ whereas no similar result occurred in N₂. In NH₃, 93 wt% of carbon was removed at 600 °C and the carbon content in the pyrolyzed product at 900 °C was only 0.37 wt%. At the same time, the conversion from polymer to ceramics was almost completed at 900 °C. Moreover, the sample acquired at 900 °C was amorphous boron nitride (BN), while that of further annealing at 1600 °C showed characteristic of turbostratic BN (t-BN). Additionally, the BN with nearly stoichiometric composition exhibited good oxidation resistance even up to 900 °C in air.     

Determination of paraffin and aromatic hydrocarbon type chemicals in liquid distillates produced from the pyrolysis process of waste plastics by isotope-dilution mass spectrometry

Isotope dilution mass spectrometry was developed for the determination of composition of paraffins, olefins, naphthenes and aromatics in distilled oil produced from the pyrolysis reaction of mixed waste plastics using labeled hydrocarbon internal standards including octane-d₁₈, dodecane-d₂₆, hexadecane-d₃₄, benzene-d₆, toluene-d₈, ethylbenzene-d₁₀, 1,3,5-trimethylbenzene-d₁₂ and naphthalene-d₈. This technique made it possible to thoroughly quantify more than three hundred peaks in plastic-derived pyrolysis oil, classify pyrolysis oil into four hydrocarbon groups of paraffin, olefin, naphthene and aromatic, and determine the weight percent of each hydrocarbon group simultaneously. Compared with commercially available petroleum oil, distilled plastic-derived pyrolysis oil contained much more aromatics amounting to 60-82 wt% of whole hydrocarbons. Toluene (C7-benzene) and trimethylbenzenes (C9-benzenes) were the predominant species amounting to 40-50% of whole hydrocarbons in pyrolysis oil with a gasoline range boiling point and 25-35% of whole hydrocarbons in pyrolysis oil with a diesel range boiling point, respectively.