Volatility and phase stability of petrol blends with ethanol

Blending ethanol in to petrol can be associated with problems related to volatility and phase stability of the blends. Ethanol up to 20 vol% in petrol forms an azeotropic mixture with hydrocarbons. Ethanol has affinity to water and air humidity and it increases the water solubility in ethanol-petrol blends. In this work, the influence of ethanol up to 10 vol%, ETBE up to 10 vol% and hydrocarbon composition over volatility, distillation characteristics and miscibility of ethanol-petrol blends with water was studied. It was found that higher content of saturated hydrocarbons in petrol increased the vapour pressure of azeotropic ethanol blend. Aromatics and alkenes influenced the azeotrope vapour pressure, phase separation temperature and ethanol extraction in a positive way. The results showed that the ETBE can soften effects of the ethanol blending to petrol. ETBE decreased the vapour pressure and the phase separation temperature of the ethanol-petrol blends.     

Upgrading of bio-oil in supercritical ethanol: Catalysts screening,solvent recovery and catalyst stability study

Supercritical upgrading of bio-oil is an effective method to upgrade bio-oil. In this paper, upgrading of bio-oil was carried out in supercritical ethanol with the aim of catalyst selection, reducing solvent consumption and catalyst stability study. Compared with Ru/HZSM-5, C-supported catalysts (Pt/C, Pd/C, and Ru/C) gave better catalytic performance. Over the C-supported catalysts, the heating value increased from 21.45 MJ/kg to about 30 MJ/kg and the pH value increased from 3.13 to about 5.5. The relative content of desired products reached as high as 80% over Ru/C. The ratio of ethanol to bio-oil was further reduced to about 1:1 by solvent recovery and reutilization. The relative content of desired products particularly that of esters increased with the recovered solvent. Catalytic stability study of Ru/C showed that the relative content of desired products decreased gradually with the number of catalyst recycle times while the consumption of hydrogen decreased mainly in the first recycle. Coke deposition and sintering of metal particles were the main reasons for the deactivation of Ru/C.     

Separation of bio-oil by molecular distillation

In this study, KDL5 molecular distillation apparatus manufactured by the UIC Corporation was adopted to separate bio-oil, which came from a bench-scale fluidized-bed fast pyrolysis reactor at a feeding rate of 1 kg/h. A maximum distillate yield of 85% was obtained without obvious coking or polymerization during the molecular distillation process. The effect of distillation temperature on physical and chemical characterization of each bio-oil fraction was investigated. Statistical calculations showed that molecular distillation was successful in the separation of bio-oil. A separation factor was proposed to reflect the ability of isolating the chemicals contained in the bio-oil using molecular distillation.     

Production of bio-oil from fixed bed pyrolysis of bagasse

The objective of this work was to produce renewable liquid fuel (bio-oil) from locally produced bagasse by pyrolysis in a batch feeding and fixed bed reactor. The experiments were performed at different temperatures ranging from 300 to 600 °C. The bio-oil was collected from two condensers of different temperatures and defined as oil-1 and oil-2. The maximum total yield of bio-oil was found to be 66.0 wt% based on bagasse. The carbon based non-condensable gases were CO, CO₂, methane, ethane, ethene, propane and propene. The density and viscosity of oil-1 were found to be 1130 kg/m³ and 19.32 centipoise and that were 1050 kg/m³ and 4.25 centipoise for oil-2, respectively. The higher heating values (HHV) of them were 17.25 and 19.91 MJ/kg, respectively. The pH of the bio-oils was found to be around 3.5 and 4.5 for oil-1 and oil-2, respectively. The water, solid and ash contents of oil-1 and oil-2 were determined and found to be around 15, 0.02 and 0.03 wt% and 11, 0.01 and 0.02 wt%, respectively based on bagasse.     

Combustion heat release analysis of ethanol or n-butanol diesel fuel blends in heavy-duty DI diesel engine

An experimental study is conducted to evaluate the effects of using blends of diesel fuel with either ethanol in proportions of 5% and 10% or n-butanol in 8% and 16% (by vol.), on the combustion behavior of a fully-instrumented, six-cylinder, turbocharged and after-cooled, heavy duty, direct injection (DI), ‘Mercedes-Benz’ engine installed at the authors’ laboratory. Combustion chamber and fuel injection pressure diagrams are obtained at two speeds and three loads using a developed, high-speed, data acquisition and processing system. A heat release analysis of the experimentally obtained cylinder pressure diagrams is developed and used. Plots of histories in the combustion chamber of the heat release rate and temperatures reveal some interesting features, which shed light into the combustion mechanism when using these promising bio-fuels that can be derived from biomass (bio-ethanol and bio-butanol). The key results are that with the use of these bio-fuels blends, fuel injection pressure diagrams are very slightly displaced (delayed), ignition delay is increased, maximum cylinder pressures are slightly reduced and cylinder temperatures are reduced during the first part of combustion. These results, combined with the differing physical and chemical properties of the ethanol and n-butanol against those for the diesel fuel, which constitutes the baseline fuel, aid the correct interpretation of the observed engine behavior performance- and emissions-wise.     

Formation of porous silicon at elevated temperatures

The features of electrochemical formation process of porous silicon (PS) at the temperatures above the room temperature have been studied. It was found that besides electrochemical dissolution, chemical etching takes part in the formation process of PS even for concentrated HF electrolyte. The role of chemical etching increases with temperature causing an increase of the porosity and the crater depth. The temperature dependence of chemical etching rate has been established. Obtained results enable to conclude that OH⁻ ions play a major role in the chemical etching. Electrochemical etching allows to fabricate PS with good surface quality at the temperatures at least below 65 °C provided that HF electrolyte is concentrated.     

Bio-coke from upgrading of pyrolysis bio-oil for co-firing

Bio-cokes were formed by upgrading pyrolysis oils from wheat spent grain and rapeseed meal biomasses using a thermo-t vis-breaking technology. The bio-cokes presented moisture levels below 2 wt.%, were virtually ash-free and had very low oxygen contents in the range of 10–14 wt.%. Their calorific values were in the range of 29–37 MJ/kg comparable to that of bituminous coal. About 15–25 wt.% of the original biomass on dry ash-free basis was converted into the ash-free bio-coke and about 20–40% of the heating value of the original biomass was retained in the bio-coke. From TGA analysis it was found that the fuel properties of the bio-coke from wheat spent grain were comparable to those of coal, where blends of up to 50 wt.% of WSG bio-coke with coal showed virtually similar oxidation behaviour to that of coal. This work shows that low-density biomass can be transformed into high density bio-coke that can logistically be treated like coal and indicates that co-firing with bio-coke can easily exceed current levels in the future.     

Synthetic fuel production from tea waste: Characterisation of bio-oil and bio-char

The pyrolysis of tea waste was studied for determining the main characteristics and quantities of liquid and solid products. Particular investigated process variables were temperature (673-973 K), heating rate (5-700 K min⁻¹) and nitrogen gas flow rate (200-800 cm³ min⁻¹). The maximum oil and char yields are 30.4 (773 K) and 43.3% (673 K), respectively. The liquid and its aliphatic sub-fraction were characterized by elemental analysis, FT-IR, ¹H NMR, and GC/MS. The char was characterized with elemental analysis, SEM, BET, and FT-IR techniques. The aliphatic sub-fraction of the obtained bio-oil contains predominantly n-alkanes and alkenes, and branched hydrocarbons. According to the experimental results the liquid products can be used as liquid fuels, whereas the solid product seems to be not suitable for adsorption purposes, due to having low surface areas.     

Upgrading of bio-oil: Effect of light aldehydes on acetic acid removal via esterification

Since fast pyrolysis derived bio-oils are not a simple hydrocarbon mixture, but rather contain a variety of oxygenated compounds including acids and aldehydes, upgrading is required in order to use bio-oils as transportation fuels. Esterification is one of the attractive routes to convert acids contained in bio-oil to more desirable esters. Although organic acid esterification is a simple reaction, no work has been reported as to whether the presence of other reactive oxygenated compounds such as aldehydes affect the reaction. In this study of bio-oil model compounds, the impact of acetaldehyde and propionaldehyde on acetic acid esterification was investigated on organic–inorganic mesoporous silica functionalized with propylsulfonic acid groups. No impact of these two aldehydes on acetic acid consumption was seen at 100 °C, regardless of the concentration of ethanol used. However, at 70 °C and 50 °C, the conversion of acetic acid was observed to be lowered during the reaction in the presence of the aldehydes. When either of the aldehydes were present, the acetic acid conversion was about 6% and 28% lower than that in its absence at 70 °C and 50 °C, respectively. It appears that the more significant aldehyde impact on acetic acid conversion seen at the lower reaction temperatures was due to the esterification rate being slow relative to the rapid competitive acetalization rate of the aldehydes with ethanol.     

Characterization of pyrolytic lignins with different activities obtained from bio-oil

Pyrolytic lignin, the water-insoluble fraction in bio-oil, often shows a high content and has strong intermolecular interactions with other compounds in bio-oil. In order to obtain pure pyrolytic lignin and facilitate the utilization of aqueous phase obtained from water extraction of bio-oil, methanol–water extraction method was employed to further separate the bio-oil water-insoluble phase in this paper. Different technologies, including Fourier transform infrared spectroscopy, gel permeation chromatography, and nuclear magnetic resonance, were adopted to characterize the structures of pyrolytic lignins with different activities obtained through this method. Both the heating value and the polymerization degree of high-molecular-weight pyrolytic lignin were higher than those of low-molecular-weight pyrolytic lignin. The molecular weight distribution of high-molecular-weight pyrolytic lignin was relatively wider, among which the contents of dimers to pentamers all accounted for 12% –18%,while the low-molecular-weight pyrolytic lignin mainly consisted of trimers(75.38%). The pyrolytic lignins had similar basic structures, both of which contained syringyl and guaiacyl units, whereas the low-molecular-weight pyrolytic lignin had more abundant syringyl units, reactive carbonyl groups and hydroxyl groups. Meanwhile,thermogravimetric study revealed that the final char residue yield of low-molecular-weight pyrolytic lignin was lower than that of high-molecular-weight pyrolytic lignin.     

Steam pyrolysis of an industrial waste for bio-oil production

Potato skin, a food industry waste, was pyrolysed under three different atmospheres namely static, nitrogen, and steam to produce bio-oil and its derivatives. The oil yield obtained at 550 °C was 24.77% in static atmosphere, whereas it reached to 27.11% in nitrogen atmosphere. Moreover, the use of steam caused a sharp increase of oil yields up to 41.09% with a steam velocity of 1.3 cm s^− 1. TG-DTA analyses were applied on the raw material to investigate the thermal degradation. Liquid products obtained under the most suitable conditions were characterized by elemental analyses, FT-IR and ¹H NMR. In addition, column chromatography was employed to separate the bio-oil into its derivatives. Asphaltene fraction of bio-oil is decreased under steam atmosphere. Gas chromatography was also used to investigate the C distributions. The characterization has shown that the bio-oil obtained under steam atmosphere was more beneficial than those obtained under both static and inert atmospheres. Further comparison of H/C ratios of pyrolysis oils with conventional fuels indicates that the H/C ratios of the oils obtained in this study lie between those of light and heavy petroleum products. It can be concluded that potato skin could be evaluated as a promising biomass candidate of bio-oil production.     

An in situ reduction approach for bio-oil hydroprocessing

An in situ reduction treatment, combination of reduction and esterification, was investigated to refine bio-oil. Over Raney Ni and zeolites-supported noble metal (Pd and Ru) catalysts, the reductant formic acid decomposed into hydrogen and carbon dioxide, and then hydrogen reduced the bio-oil while compressible CO₂ dissolved in methanol to form a CO₂-CH₃OH expanded liquid. The results showed that Raney Ni and zeolites-supported Ru were highly active in this heterogeneous catalytic system. The reactions preformed at 150-230 °C for 5-7 h would give a better upgraded bio-oil with a high yield of 80-90 wt.%. The unsaturated components in bio-oil were reduced substantially without obvious coke formation, and the oxygen content was lowered by ca. 5 wt.%. Organic acids were converted into esters through the esterification with methanol, and the properties of hydrogenated bio-oil were improved: the pH value increased from 2.17 to ca. 4.5; the higher heating value approached to 22 MJ/kg, and the viscosity decreased from 5.31 to ca. 4.0 mm²/s.     

二硫化钼催化加氢生物质油的研究

以微米二硫化钼(micro-MoS2)和纳米二硫化钼(nano-MoS2)为催化剂,在一定温度(250℃)和一定压力(2MPa)下,在间歇反应釜中进行生物质油的催化加氢实验,考察了不同粒径二硫化钼对生物质油催化加氢效果以及它们对产物性能的影响。同时,与生物质油催化加氢常用催化剂(Pd/C)进行对比,以期获得较佳的加氢催化剂。结果表明,在此温度条件下,nano-MoS2催化获得的精制油具有相对较高的H/C比值,由初始生物质原油的2.35增加到3.38;而Pd/C和micro-MoS2催化所得精制油具有相对较高的产率,分别为58.1%和55.7%。     

加压碳化法制备碱式碳酸镁新工艺研究

碱式碳酸镁是一种性能优良的填充剂和分散剂,目前主要采用白云石碳化法或苦土粉-硫酸-碳酸氢铵法生产,流程复杂,污染严重。研究了在加压条件下以氢氧化镁浆液和二氧化碳气体为原料制备碱式碳酸镁新工艺。考察了反应温度、反应时间、二氧化碳分压对产品质量的影响。采用扫描电子显微镜（SEM）、X射线衍射仪(XRD)和热重-差热分析仪（TG-DTA）对产品的形貌、晶体结构及热失重进行了表征。结果表明,在反应温度为120 ℃,二氧化碳分压为0.22 MPa,反应时间为3 h时,可得到纯度较高、形貌为规则的六方薄片状的产品。     

Combustion characteristics and kinetics of bio-oil

The combustion characteristics of bio-oils derived from rice husk and corn were studied by thermogravimetry analysis. According to the thermo-gravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) curves of bio-oils in air and nitrogen atmosphere, we analyzed the combustion characteristics of different kinds of bio-oils in different atmospheres and worked out the combustion kinetics parameters of the bio-oil, providing reliable base data for the burning of bio-oil. The thermogravimetry indicated that the combustion process of bio-oil was divided into three stages. At the same time, the combustion process can be described by different order reaction models, and with the method of Coats-Redfern, the activation energy and frequency factor of different kinds of bio-oils were obtained.     

Combustion and emissions behavior for ethanol–gasoline blends in a single cylinder engine

This paper investigates the effect of using gasoline–ethanol mid-level blends (0–20% ethanol) on engine performance and exhausts emissions on a single cylinder engine by AVL model 5401, spark ignited and electronically controlled with DOHC. Engine tests were conducted for different lambda values, brake power and brake specific fuel consumption, while exhaust emissions were analyzed for carbon monoxide, unburned hydrocarbons and nitrogen oxides. Using blends at different proportions for a steady state of 2000 rpm at partial charge minimizing load and speed variations at a minimum in order to prevent them from being a measurable factor. Results showed that at constant mass fuel rates, the increase in burning rate associated with ethanol is tempered by the process combustion speed reduction related to the enleanment proportional to the ethanol added to gasoline. Blends up to 10% have marginal effects in combustion rates when compared to non-oxygenated fuels, but for 20%, combustion process slows down and increases cyclic dispersion in the results, the effect in fuel consumption observed was lower than predicted by the reduction of energy content in the gasoline, suggesting positive effects in combustion efficiency.     

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.     

Vapor-liquid equilibria of carbon dioxide and nonionic surfactant system at elevated pressures

Aqueous solutions of the polyoxyethylene nonionic amphiphiles have been extensively investigated at atmospheric pressure, but only a few data of nonionic amphiphile — carbon dioxide system are available at elevated pressures. Isothermal vapor-liquid equilibrium data for the binary ethylene glycol propyl ether (C3E1) — carbon dioxide system at 313.15 K, 323.15 K were measured at elevated pressures. We used two-phase circulating type equipment with a view cell. Modeling of the experimental data has been performed using the Peng-Robinson equation of state, statistical associating fluid theory (SAFT) and Sanchez-Lacombe equation of state.     

Morphology of high-density polyethylene pipes stored under hydrostatic pressure at elevated temperature

The morphology of unimodal and bimodal high-density polyethylene (HDPE) pipes during a hydrostatic pressure test was studied in detail using ¹H solid-state NMR. Characterizing the changes of the molecular network during such a test is of key importance for understanding the long-term properties of different HDPE pipe grades. The changes in amount, thickness, and molecular mobility of the crystalline phase, the interface, and the amorphous phase of the two pipe grades with the storage time have been quantified for the first time. The most sensitive microscopic parameter to storage is the molecular mobility of the amorphous phase, with the strongest changes shown by the unimodal HDPE. The density of the tie-molecules is not the main factor controlling the very different behavior of the two pipe grades, but rather it is the density of the entanglements. The NMR results offer unprecedented insights into the changes in the molecular network and support existing deformation models.     

Experimental determination of laminar burning velocity for butanol and ethanol iso-octane blends

The potential of butanol as an additive in iso-octane used as gasoline fuel was characterized with respect to laminar combustion, and compared with ethanol. New sets of data of laminar burning velocity are provided by using the spherical expanding flame methodology, in a constant volume vessel. This paper presents the first results obtained for pure fuels (iso-octane, ethanol and butanol) at an initial pressure of 0.1 MPa and a temperature of 400 K, and for an equivalence range from 0.8 to 1.4. New data of laminar burning velocity for three fuel blends containing up to 75% alcohol by liquid volume are also provided. From these new experimental data, a correlation to estimate the laminar burning velocity of any butanol or ethanol blend iso-octane-air mixture is proposed.