The effect of hydrothermal pretreatment on the structure and fast pyrolysis behaviors of ShengLi lignite

The structure and composition of coal determine its fast pyrolysis characteristics,and the study of the relationship between them can play an important role in the efficient and clean utilization of coal.So,in this work,hydrothermal pretreatment was used to artificially change the structure and composition of ShengLi (SL) lignite,which was used to investigate the influence of structural changes on pyrolysis.The physicochemical structure and composition of samples were characterized by X-ray diffraction,specific surface area and porosity analyzer,solid-state 13C nuclear magnetic resonance,Fourier transform infrared spectroscopy,and elemental analyzer.Pyrolysis experiments were carried out in a powder-particle fluidized bed reactor,and the distribution and composition of the pyrolysis products were ana-lyzed.The gasification activity of char was investigated by thermogravimetric analysis with a CO2 atmo-sphere.The results show that hydrothermal pretreatment (HTP) can destroy the cross-linking structure of SL lignite,and affect its aromaticity,pore structure,functional group,and carbon structure to change the distribution and composition of pyrolysis products of SL lignite,especially the composition of tar.Finally,the structure-activity relationship between the structure,composition,and pyrolysis characteristics of coal was comprehensively studied.     

微波场对小麦淀粉性质的影响

研究了微波辐射前后小麦淀粉物化性质的变化。采用微波对水分含量30％的小麦淀粉进行处理。结果表明微波处理淀粉颗粒表面出现小孔,微波处理增强了对应X射线衍射峰的强度,降低了膨胀度、溶解度、析水率以及焓值,提高了糊化转变温度、转变温度范围。小麦淀粉经处理后糊化起始温度升高、黏度降低,但其黏度曲线不改变。以上数据表明在淀粉颗粒内无定形区和结晶区的直链淀粉与直链淀粉、直链淀粉与支链淀粉发生交互作用,产生了新的不同稳定性的结晶体,从而导致微波处理淀粉内部更加有序的结晶排列。     

Combined effects of pressure and ion-exchangeable metallic species on pyrolysis of Victorian lignite

A set of ion-exchanged samples prepared from Loy Yang lignite was pyrolyzed in a wire-mesh reactor at elevated pressures from 1 to 36 bar. The tar yields from the pyrolysis of H-form (acid-washed) sample at a fast heating rate of 1000 °C s⁻¹ were drastically reduced by increasing pressure to 6 bar and then remained unchanged with further increase in pressure to 36 bar. This behavior of the tar yield was in sharp contrast to that from the raw lignite which showed a minimum with increasing pressure. The sensitivities of the tar yields to changes in the heating rate were also suppressed by increasing pressure. The tar yields from Ca-form and Na-form samples (prepared by ion-exchanging Ca and Na on the H-form sample, respectively) were not very sensitive to changes in the heating rate and pressure up to 11 bar. At 20 bar, the tar yields from the Na-from sample nearly doubled whereas from the Ca-form sample nearly halved compared to those respective values at 1 bar. Although increasing pressure is thought to cause changes in the intra-particle mass transfer processes of volatile precursors, the rate of formation of volatile precursors tends to dictate the kind of mass transfer process responsible for the release of volatiles. Therefore, depending on the pyrolysis condition, bulk diffusion or forced flow would dominate the mass transfer processes for the release of volatiles. The introduction of cations is thought to result in irreversible changes in the lignite structure and not only control the process of formation but also the amount of volatile precursors and in turn alter the effects of pressure. Valence and catalytic activity of cations seem to play important roles in determining pyrolysis products distribution at elevated pressures.     

Release of volatiles from the pyrolysis of a Victorian lignite at elevated pressures

A Loy Yang lignite sample was pyrolysed in a wire-mesh reactor at pressures from 1 to 61 bar. The char yield did not show considerable sensitivity to changes in pressure or heating rate and was mainly a function of temperature. However, the tar yield was sensitive to changes in pressure, holding time and heating rate. The tar yield at 1000 K s⁻¹ showed a minimum at around 6-11 bar. The tar yield at 1 K s⁻¹ increased slightly with increasing pressure from 1 to 20 bar. The UV-fluorescence spectroscopy of the tar samples indicated that the release of larger (three or more fused rings) aromatic ring systems was also greatly affected by increases in pressure. It is believed that increases in pressure have slowed down the bulk diffusion within meso- and macro-pores in the pyrolysing lignite/char particles. During the extended stay within the char particle, volatile precursors were thermally cracked to form mainly gaseous species as well as very small amounts of char. At very high pressures where the diffusion was very slow, the formation of light gases caused the pressure to build up within the particles, inducing the forced flow of volatile precursors out of the particles and leading to increased tar yield.     

Combined conventional thermal and microwave drying process for typical Chinese lignite

A combined conventional and microwave drying process for Ximeng lignite was investigated in this paper. Samples were firstly dehydrated by hot air to achieve a conversion moisture content, and then were managed to final moisture content by microwave drying. Results showed that the drying rate was significantly improved in the decreasing rate period by microwave drying, approximately 3–5 times faster than that of conventional drying. Finally, the orthogonal test was used to clarify the effects of each factor on the energy consumption, and the magnitude ranking order was conversion moisture content?>?microwave power?>?hot air temperature.     

Synergies in co-pyrolysis of Thai lignite and corncob

The results from TGA experiments at the temperature range of 300–600 °C evidently distinguished the different pyrolysis behaviours of lignite and corncob; however, no clear synergistic effects could be observed for the mixture. The investigation of co-pyrolysis in a fixed-bed reactor, however, found significant synergies in both pyrolysis product yields and gas product compositions. The solid yield of the 50:50 lignite/corncob blend was much lower (i.e. 9%) than expected from the calculated value based on individual materials under the range of temperatures studied, and coincided with the higher liquid and gas yield. The synergistic effect in product gas composition was highly pronouncing for CH₄ formation, i.e. three times higher than the calculated value at 400 °C. Possible mechanisms were described including the interaction between corncob volatiles and lignite particles, and the effect of the heat profiles of lignite and corncob pyrolysis on the temperature dependent reactions. The enhanced devolatilisation of the blend was explained by the transfer of hydrogen from biomass to coal as well as the promotion of low-temperature thermal decomposition of lignite by exothermic heat released from corncob pyrolysis. Moreover, water, which was one of the major components in corncob volatiles produced mainly at around 200–375 °C, can also be expected to act as a reactive agent to promote the secondary tar cracking producing more CH₄.     

微波辐射下2-氨基苯并咪唑的合成与表征

在微波辐射下,以NaOH为催化剂,由氨基氰和邻苯二胺合成2-氨基苯并咪唑,通过正交实验确定了最优化工艺条件:微波辐射时间为165 min,微波功率为162 W,反应物物质的量比为1∶1.2。产物的收率为83%,其结构经过数字熔点仪、红外光谱仪和1HNMR表征确认。     

An experimental study of sulphate transformation during pyrolysis of an Australian lignite

The transformation of sulphate minerals during pyrolysis of an Australian lignite has been studied using pure sulphates (CaSO₄, FeSO₄ and Fe₂(SO₄)₃), a high mineral (HM) lignite sample and a low mineral (LM) lignite sample collected from different locations of the same deposit, and samples of acid-washed LM doped with sulphates (CaSO₄+ LM and FeSO₄+ LM), respectively. Thermogravimetric analysis and fixed-bed reactor techniques were used for the pyrolysis experimentation and the lignite samples and their chars were analysed using FTIR and XRD. The TGA experiments showed that CaSO₄ decomposes between 1400 and 1700 K in nitrogen and a 50/50 N₂/CO₂ mixture, while in air CaSO₄ decomposes between 1500 and 1700 K. Using a TGA-MS it was found that only a small fraction of CaSO₄ in CaSO₄+ LM decomposed at 653 K, releasing SO₂. CaSO₄ was still observed in the char recovered at 1073 K as confirmed by the FTIR and XRD analysis. FeSO₄·7H₂O released the bound water below 543 K and the remaining FeSO₄ decomposed between 813 and 953 K. FeSO₄ in FeSO₄+ LM decomposed at 500 K to release SO₂. The inherent sulphates in HM were dominated by iron sulphates which started to decompose and release SO₂ at around 500 K and all sulphate had been decomposed at 1073 K. It was observed that during the fixed-bed pyrolysis at 1073 K in nitrogen, approximately 36% of the total sulphur in the CaSO₄+ LM decomposed, 88% of the total sulphur in the FeSO₄+ LM decomposed and around 76% of the total sulphur in HM decomposed. It was also confirmed that FeSO₄+ LM produced more volatile sulphur than CaSO₄+ LM during pyrolysis.     

乌拉盖褐煤热解特性及反应动力学参数研究

为获得较好的褐煤半焦制备工艺参数,研究了不同制备条件(热解终温、升温速率、原煤粒径、热解气氛)下制得的乌拉盖褐煤半焦的燃烧性能和燃烧动力学参数。结果表明,热解终温对半焦品质的影响最大,热解升温速率、原煤粒径和热解气氛对半焦燃烧特性的影响不显著。热解终温由350℃升至600℃时,反应指数RI由235℃升至292℃,半焦着火性能变差;燃尽指数Cb由4.68升至6.15,半焦燃尽性能变差;爆炸指数Kd由2.54降至0.46,半焦爆炸倾向性变低;反应活化能由44.4 k J/mol升至63.4 k J/mol,半焦燃烧动力学特性变差。热解终温为520℃时制得的半焦反应指数、燃尽指数、爆炸指数和反应活化能分别为265℃,5.34、0.80和53.2 k J/mol,属于易着火、易燃尽、中等爆炸燃料,燃烧特性良好。     

微波辐照下炭材料升温特性试验研究

为研究微波功率、活性炭粒径、载气流速对活性炭升温规律的影响,利用微波加热综合试验平台进行活性炭微波加热升温试验,研究了不同因素下活性炭的升温特性。结果表明:相同前提下,随着微波功率的增大,2种活性炭(木质活性炭、煤质活性炭)的升温速率不断加快,最高温度随之提高,微波功率从240~400 W时,木质活性炭在10~16 min平均温度增幅达93℃,明显大于煤质活性炭;增加粒径导致木质活性炭达到的最终温度有所降低,且升温速率减小;提高载气流速可减缓木质活性炭的升温速率并降低其最高温度。获取最高活性炭温度的最佳试验工况为微波功率P为400 W、活性炭粒径d≤1 mm、载气流速Q为60 L/h。     

Effect of microwave irradiation on the physical properties and structures of wool fabric

Microwaves are high frequency radio waves which are capable of penetrating many materials and causing heat to be generated in the process. To investigate the effect of microwave irradiation on the physical property, chemical structure, surface morphological structure, and fine structure of wool fabric, wool fabric was treated with microwave irradiation under variety of conditions in terms of the power and the time of microwave treatment. The breaking strength, breaking elongation, and whiteness of the treated wool fabric in different humid state were investigated. The structures of the untreated and treated wool were investigated with Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), and Laser Raman spectroscopy (LRS). The results show that the physical properties of the treated wool fabrics were changed with microwave irradiation time and power. The chemical structure had not significant change. The surface morphological structure, the concentration of cystine S S bonds and crystallinity of the treated wool were changed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The effect of temperature and pressure on the physicochemical properties of petroleum diesel oil and biodiesel fuel

Three commercial fuels were studied: biodiesel (based mainly of the fatty acids methyl esters of rapeseed oil), diesel oil Ekodiesel Ultra (standard petroleum diesel oil with sulphur content less than 10 mg/kg), and ON BIO 10 (blend of 20 vol.% of biodiesel with 80 vol.% of standard petroleum diesel oil with sulphur content less than 10 mg/kg). The speeds of sound were measured within the temperatures from 293 to 318 K and at pressures from 0.1 to 101 MPa. The densities and heat capacities were measured under atmospheric pressure in the temperature range from 273 to 363 K and 283 to 359 K, respectively. Using the experimental results, the physicochemical properties such as: density, isentropic bulk modulus, heat capacity, and isobaric thermal expansion were calculated in the same temperature and pressure range as the speed of sound was measured. The results obtained show that although the bulk modulus of ON BIO 10 is higher than that of diesel oil Ekodiesel Ultra over the whole pressure range, the difference is rather small and can be compensated by temperature. Isobaric thermal expansivity of biodiesel decreases with pressure slightly less than that of the diesel oil Ekodiesel Ultra. It is approximately independent of temperature and composition of the fuel at pressures 40 ± 5 MPa.     

Insights into the physicochemical properties of coffee oil

The lipid fraction of roasted coffee is an interesting ingredient that could be used in a large number of food formulations. Coffee oil has peculiar flavouring as well as nutraceutical characteristics. The feasibility of the use of coffee oil as ingredient greatly depends not only on its chemical characteristics but also on its physical properties. The crystallisation and melting properties of the coffee oil extracted from Arabica roasted coffee powder were determined by using synchrotron X‐ray diffraction coupled with differential scanning calorimetry. The fatty acid composition and the flavour profile were also assessed by using GC and GC‐MS analyses, respectively. The main fatty acids found in coffee oil are linoleic and palmitic acid. Significant amounts of stearic and oleic acid are also present. These chemical characteristics are linked to the phase transition behaviour. The crystallisation of coffee oil occurs at 6.5 ± 0.3 °C, independently of the cooling rate applied (from 0.5 to 10 °C/min). A unique crystalline structure was identified: a double chain length (2L) β' structure (55.29 Å). The sole formation of the β' form indicates that this metastable crystal is the only one that one should expect in foods containing coffee oil stored below 7 °C.     

Effects of high-pressure homogenization on physicochemical properties and storage stability of switchgrass bio-oil

A high-pressure homogenization (HPH) technique was used to improve the physicochemical properties and storage stability of switchgrass bio-oil. The viscosity, ethanol-insoluble fraction, and mass average molecular weight (Mw) of the bio-oil decreased significantly, and particle size became smaller after HPH processing; however, no significant changes were detected in heating value, water content, density, pH value, or ash content. The bio-oil's chemical composition changed after HPH: amounts of some compounds (furfural, levoglucosan, diethoxymethyl acetate, and lignin-derived compounds) increased, while others (acetic acid and 1,2-ethanediol) decreased. The homogenization processing remarkably improved switchgrass bio-oil stability: the viscosity of bio-oil homogenized at 100 MPa increased by only 13.9% after storage at 40 °C for 60 days, whereas that of unhomogenized oil increased 56% after the same storage period. The operating cost was very modest at only $0.0102/L for bio-oil HPH processing at 100 MPa.     

Turkey liver: Physicochemical characteristics and functional properties of protein fractions

Turkey liver is an important edible meat by-product. However, it is generally unprocessed, underutilized and low-priced compared to mammalian livers. The present investigation was conducted to provide information on physicochemical composition and functional characteristics of turkey liver. Proximate composition (%) was: moisture (72.3 ± 1.2), protein (21.9 ± 0.6), fat (2.9 ± 1.6), carbohydrate (1.4 ± 0.7), and total ash (1.5 ± 0.1). Cholesterol, glycogen and total heme pigments (g/kg) in the turkey liver were 2.05 ± 0.06, 5.36 ± 0.01 and 2.3 ± 0.08, respectively. Contents in saturated, monounsaturated and polyunsaturated fatty acids (%) were 42.5, 14.6 and 32.6 respectively. Interestingly, turkey liver fat also contains 5% of camphor (oxygenated monoterpene). Mineral concentrations (mg/kg) in liver were: Na (817 ± 14), K (1390 ± 90), Ca (31.4 ± 0.3), Mg (23 ± 0.4), Fe (161 ± 5), Zn (40 ± 2) and Cu (34 ± 2). Liver proteins extracted at 5 or 10 g/l NaCl showed the highest foaming capacity (P < 0.05). Addition of xanthan (1-3 g/l) to liver proteins improved both foam formation and its stability (P < 0.05). Turkey liver also showed interesting emulsifying properties. The emulsion stability of liver proteins was more pronounced at high NaCl concentration (20 g/l). The highest emulsion stability was obtained at acidic or basic pH values (P < 0.05) and decreased at pH 6.     

Evolvement behavior of microstructure and H2O adsorption of lignite pyrolysis☆

The effect of pyrolysis on the microstructure and moisture adsorption of lignite was investigated with low field nuclear magnetic resonance spectroscopy. Changes in oxygen-containing groups were analyzed by Fourier transform infrared spectroscopy(FTIR), and H2 O adsorption mechanism on the surface of lignite pyrolysis was inferred. Two major changes in the pore structure of lignite char were observed as temperature increased in 105–200 °C and500–700 °C. Pyrolysis temperature is a significant factor in removing carboxyl and phenolic hydroxyl from lignite.Variation of ether bond content can be divided into three stages; the content initially increased, then decreased,and finally increased. The equilibrium adsorption ratio, content of oxygen-containing groups, and variation of pore volume below 700° were closely correlated with each other. The amount of adsorbed water on char pyrolyzed at700 °C increased. Moreover, the adsorption capacity of the lignite decreased, and the adsorption state changed.     

微波辐射对洗涤剂用酶的作用

蛋白酶分别经过1000W微波辐射8s和10s后，在实验条件下，活性达到最大值，分别提高了11％和16％。加入标准粉后，二者去污比值几乎没有变化。微波辐射后的两种蛋白酶放置于室温下2个月，其活性均随时间变化而缓慢下降。脂肪酶分别经过1000W微波辐射5s后，活性达到最大值，分别提高了22％和7％。加入标准粉后，二者去污比值几乎没有变化。微波辐射后的两种脂肪酶放置于室温下4个月，活性均随时间变化回到未经微波辐射的最初状态。     

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.     

Effect of B-site ion substitution on chemical bond characteristics and microwave dielectric properties of ZnWO4 ceramics

Herein, the influence of Mo⁶⁺ substitution on the crystal structure, microstructures, chemical bond characteristics, vibration characteristics and microwave dielectric properties of ZnMo_xW_1-xO₄(x = 0−0.12) ceramics prepared by a solid-state reaction were investigated. The results show that Mo⁶⁺ substitution does not produce secondary phase, the densification temperature decreases from 1100 to 925 ℃, and Q × f values increased from 19605 GHz (x = 0) to 61640 GHz (x = 0.06) at 925 ℃, which resulted from the packing fraction, U_tW-O and microstructures. Also, the τ_f values were optimized to −34 ppm/°C due to changes in the degree of structural order and stability of chemical bonds.Af_iW-O, molecular polarizability and porosity first led to an increase in permittivity and decrease thereafter. The ZnMo_0.06W_0.94O₄ ceramics sintered at 925℃ exhibited satisfactory properties (ε_r = 15.10, Q × f = 61,640 GHz, and τ_f = -34 ppm/°C), providing a potential candidate for microwave devices.