Transportation fuels from co-processing of waste vegetable oil and gas oil mixtures

Hydroprocessing catalysts, sulfided Ni–W (on mesoporous silica–alumina) and Ni–Mo (on mesoporous γ-alumina), under typical hydroprocessing conditions, can very effectively produce liquid fuel from mixtures of waste vegetable oil and refinery gas oil. The acidity of the catalyst controls the relative amount of diesel range (straight chain) alkanes and cracked lighter products. The yield of diesel range (250–380 °C) product varied between 60 and 90%, while kerosene (jet) range product varied between 10 and 35% depending upon the reaction conditions and type of catalyst used. The hydrodeoxygenation pathway for oxygen removal from triglyceride seems to be favored over the Ni–Mo catalyst, while decarboxylation + decarbonylation pathway is favored over the Ni–W catalyst and the respective pathways becomes more dominant with increasing vegetable-oil content in the feed. Vegetable oil conversion does not adversely influence hydrodesulfurization of gas oil indicating viability of co-processing. The activation energy for overall S-removal is much lower than that for overall O-removal. Density and acidity (TAN) of the products meet the required specification and cetane number is better than that for pure diesel.     

污泥直接液化制取生物质油试验研究

采用热化学直接液化技术处理污泥,考察了试验过程中温度、催化剂和反应停留时间3个因素对反应的影响,成功获取生物质油,并对反应产物进行分析。结果表明,温度控制在250℃、采用催化剂N且停留70 min时,可获取较高生物质油产量,产油率达25.4%。同时,处理后固体残渣体积仅为原料污泥的10%,不含寄生虫、病毒等有害微生物。该处理方法为污泥资源化、减量化、无害化处理提供了一个新途径。     

Economics of small-scale on-farm use of canola and soybean for biodiesel and straight vegetable oil biofuels

While the cost competitiveness of vegetable oil-based biofuels (VOBB) has impeded extensive commercialization on a large-scale, the economic viability of small-scale on-farm production of VOBB is unclear. This study assessed the cost competitiveness of small-scale on-farm production of canola- [Brassica napus (L.)] and soybean-based [Glycine max (L.)] biodiesel and straight vegetable oil (SVO) biofuels in the upper Midwest at 2007 price levels. The effects of feedstock type, feedstock valuation (cost of production or market price), biofuel type, and capitalization level on the cost L⁻¹ of biofuel were examined. Valuing feedstock at the cost of production, the cost of canola-based biodiesel ranged from 0.94 to 1.13 $ L⁻¹ and SVO from 0.64 to 0.83 $ L⁻¹ depending on capitalization level. Comparatively, the cost of soybean-based biodiesel and SVO ranged from 0.40 to 0.60 $ L⁻¹ and from 0.14 to 0.33 $ L⁻¹, respectively, depending on capitalization level. Valuing feedstock at the cost of production, soybean biofuels were cost competitive whereas canola biofuels were not. Valuing feedstock at its market price, canola biofuels were more cost competitive than soybean-based biofuels, though neither were cost competitive with petroleum diesel. Feedstock type proved important in terms of the meal co-product credit, which decreased the cost of biodiesel by 1.39 $ L⁻¹ for soybean and 0.44 $ L⁻¹ for canola. SVO was less costly to produce than biodiesel due to reduced input costs. At a small scale, capital expenditures have a substantial impact on the cost of biofuel, ranging from 0.03 to 0.25 $ L⁻¹.     

Hydrothermal liquefaction of spent coffee grounds in water medium for bio-oil production

Spent coffee grounds (SCG) were liquefied in hot-compressed water to produce crude bio-oil via hydrothermal liquefaction (HTL) in a 100 cm³ stainless-steel autoclave reactor in N₂ atmosphere. We investigated the effects of operating parameters such as retention times (5 min, 10 min, 15 min, 20 min and 25 min), reaction temperatures (200 °C, 225 °C, 250 °C, 275 °C and 300 °C), and water/feedstock mass ratios (5:1, 10:1, 15:1 and 20:1) and initial pressure of process gas (2.0 MPa and 0.5 MPa) on the yield and properties of the resulting crude bio-oil. The highest yield of the crude bio-oil (47.3% mass fraction) was obtained at conditions of 275 °C, 10 min retention time and water/feedstock mass ratio of 20:1 with an initial pressure of 2.0 MPa. The elemental analysis of the produced crude bio-oil revealed that the oil product had a higher heating value (HHV) of 31.0 MJ kg⁻¹, much higher than that of the raw material (20.2 MJ kg⁻¹). GC–MS and FT-IR measurements showed that the main volatile compounds in the crude bio-oil were long chain aliphatic acids and esters.     

废弃植物油再生利用的研究

文章介绍了用废弃植物油经酯交换反应制成柴油替代燃料的方法和工艺流程，并讨论了提高反应产率的最佳工艺参数。研究表明：在反应温度为70℃，当油醇的物质的量比为1：6，以NaOH为催化剂且浓度为1．0％，反应时间为20～30min时，酯交换反应制取脂肪酸甲酯(生物柴油)的产率为92％。用废弃植物油转化制成的脂肪酸甲酯，是石化柴油很好的替代能源。     

Production of hydrogen rich bio-oil derived syngas from co-gasification of bio-oil and waste engine oil as feedstock for lower alcohols synthesis in two-stage bed reactor

High efficient production of lower alcohols (C₁–C₅ mixed alcohols) from hydrogen rich bio-oil derived syngas was achieved in this work. A non-catalytic partial oxidation (NPOX) gasification technology was successfully applied in the production and conditioning of bio-oil derived syngas using bio-oil (BO) and emulsifying waste engine oil (EWEO) as feedstock. The effects of water addition and feedstock composition on the gasification performances were investigated. When the BO₂₀ and EWEO₃₀ was mixed with mass ratio of 1: 0.33, the maximum hydrogen yield of 93.7% with carbon conversion of 96.7% was obtained, and the hydrogen rich bio-oil derived syngas was effectively produced. Furthermore, a two-stage bed reactor was applied in the downstream process of lower alcohols synthesis from hydrogen rich bio-oil derived syngas (H₂/CO/CO₂/CH₄/N₂ = 52.2/19.5/3.0/9.4/15.9, v/v). The highest carbon conversion of 42.5% and the maximum alcohol yield of 0.18 kg/kg_cat h with selectivity of 53.8 wt% were obtained over the Cu/ZnO/Al₂O₃(2.5)//Cu₂₅Fe₂₂Co₃K₃/SiO₂(2.5) catalyst combination system. The mechanism and evaluation for lower alcohols synthesis from model bio-oil derived syngas and model mixture gas were also discussed. The integrative process of hydrogen rich bio-oil derived syngas production and downstream lower alcohols synthesis, potentially providing a promising route for the conversion of organic wastes into high performance fuels and high value-added chemicals.     

Catalytic pyrolysis of olive cake and domestic waste for biofuel production

The development of waste-to-energy technologies provides an integrated approach to waste management, climate protection, and sustainable devolvement. In this study, biofuels were produced from “olive cake” combined with used paper and scrap tire. A lab-scale facility was designed to carry out catalytic pyrolysis of a solid feedstock comprising 5 wt% used paper, 5 wt% scrap tire, and 90 wt% olive cake. Jordanian volcanic tuff was used as a catalyst during pyrolysis. The catalytic pyrolysis produced various proportions of gaseous, liquid, and solid biofuels. The use of catalyst influenced the composition, quality, and yield of products via cracking and reforming reactions.     

Effect of pH on continuous biohydrogen production from liquid swine manure with glucose supplement using an anaerobic sequencing batch reactor

pH is considered as one of the most important factors governing the hydrogen fermentation process. In this project, five pH levels, ranging from 4.4 to 5.6 at 0.3 increments, were tested to evaluate the pH effect on hydrogen production from swine manure supplemented with glucose in an anaerobic sequencing batch reactor system with 16 h of hydraulic retention time (HRT). The optimal hydrogen yield (1.50 mol H₂/mol glucose) was achieved at pH 5.0 when the maximum production rate of 2.25 L/d/L was obtained. Continuous hydrogen production was achieved for over 3 weeks for pH 5.0, 4.7, and 4.4, with no significant methane produced. However, as pH increased to 5.3 and 5.6, methane production was observed in the biogas with concurrent reductions in hydrogen production, indicating that methanogens could become increasingly activated for pH 5.3 or higher. Acetate, propionate, butyrate, valerate, and ethanol were the main aqueous products whose distribution was significantly affected by pH as well.     

Direct oxidation of waste vegetable oil in solid-oxide fuel cells

Solid-oxide fuel cells with ceria, ceria-Cu, and ceria-Rh anode were demonstrated to generate stable electric power with waste vegetable oil through direct oxidation of the fuel. The only pre-treatment to the fuel was a filtration to remove particulates. The performance of the fuel cell was stable over 100 h for the waste vegetable oil without dilution. The generated power was up to 0.25 W cm⁻² for ceria-Rh fuel cell. This compares favorably with previously studied hydrocarbon fuels including jet fuels and Pennsylvania crude oil.     

Pyrolysis of waste pomegranate peels for bio-oil production

In order to obtain bio-oil from the pomegranate peel which is a by-product of juice production process, the dried pomegranate peel was pyrolyzed at a heating rate of 10°C/min and different temperatures between 400 and 550°C. The highest pyrolytic oil yield of 40.47 wt% was obtained at the final temperature of 550°C. The oil product was characterized by various analysis techniques. The results showed that the oil product mostly contained fine chemicals with oxygen like phenols, furfural, and its derivatives with the carbon number in a range of C₃-C₁₀. The oil product had the potential for producing fine chemicals.     

Temperature-dependent viscosity correlations of vegetable oils and biofuel-diesel mixtures

Viscosity correlations of peanut, soy, sunflower, waste vegetable oil and its biofuel mixtures with diesel are presented based on three suggested equations. Calibrated capillary viscometers are used for measurements. Temperature is changed between the range of 20 °C and 120 °C. Correlations show small standard errors based on the method of curve fitting.     

Continuous biohydrogen production from liquid swine manure supplemented with glucose using an anaerobic sequencing batch reactor

Liquid swine manure supplemented with glucose (10 g/L) was used as substrate for hydrogen production using an anaerobic sequencing batch reactor at 37 ± 1 °C and pH 5.0 under different hydraulic retention times (HRTs). Decreasing HRT from 24 to 8 h caused an increasing hydrogen production rate from 0.05 to 0.15 L/h/L. Production rates of both total biogas and hydrogen were linearly correlated to HRT with R² being 0.993 and 0.997, respectively. The hydrogen yield ranged between 1.18 and 1.63 mol-H₂/mol glucose and the 12 h HRT was preferred for high production rate and efficient yield. For all the five HRTs examined, the glucose utilization efficiency was over 98%. The biogas mainly consisted of carbon dioxide and hydrogen (up to 43%) with no methane detected throughout the experiment. Ethanol and organic acids were the major aqueous metabolites produced during fermentation, with acetic acid accounting for 56–58%. The hydrogen yield was found to be related to the acetate/butyrate ratio.     

Comparative characteristics of compression ignited engines operating on biodiesel produced from waste vegetable oil

Performance and emission characteristics of two compression ignited engines of different compression ratios, number of cylinders, cooling system, and power output are studied. Waste vegetable oil-derived biofuel is used. Engines are fueled with B0, B20 and B100 mixtures. Thermal efficiency, brake specific consumption and engine emissions (CO, Unburned HC, O₂ and NO) are reported and comparisons are made for fuel mixtures running on both engines. Trends of emissions and performance curves are compared to the literature of the available data. It is noted that the biofuel certainly affects unburned HC emissions regardless of engine specifications and/or operating conditions. However, the type of fuel or adding biofuel to diesel may not affect parameters such as exhaust gas temperature and emissions (CO, Unburned HC, O₂, NO). These parameters may change as functions of engine specifications and operating conditions regardless of biofuel or diesel being used. These findings are supported by separate investigations using different biofuels in literature.     

Effect of agitation pretreatment on anaerobic digestion of swine manure

This study evaluated the effect of mechanical agitation pretreatment on anaerobic digestion (AD) of swine manure (SM). The results showed a remarkable increase in soluble polysaccharides, soluble proteins, and soluble chemical oxygen demand (SCOD) by 82.42%, 121.17%, and 114.89%, respectively, after the SM being agitated for 22 h. No improvement in the volatile fatty acids (VFAs) yield was observed during the agitation pretreatment. Apparently, agitation significantly accelerated the hydrolysis of SM, while it did not seem to enhance the acidification step. Batch AD experiments showed an improved accumulative methane yield by 77.89% with the pretreated SM compared to raw SM.     

An evaluation of the life cycle cost of rapeseed oil as a straight vegetable oil fuel to replace petroleum diesel in agriculture

The use of straight vegetable oil (SVO) as biofuel has been recognized as a valid substitute of diesel fuel in the agricultural sector under specific circumstances. Its direct use reduces most of the chemical processes involved when converting it into biodiesel, thus lowering harmful emissions. This study presents the economic analysis of a self-supply farming model that uses rapeseed as its fuel base. This model addresses agricultural environmental concerns and can even minimize dependence on the fluctuating costs of diesel fuel. The use of SVO in agriculture can help reduce farmers’ vulnerability to fossil fuel prices. The economic evaluation of the model proposed in this study shows clear economic benefits of introducing rapeseed to the traditional crop rotation of wheat and barley. The key factors analyzed in this model are diesel fuel price, diesel fuel grants and crop aids. The current situation in Spain favors the use of diesel fuel in agriculture rather than rapeseed SVO due to an 8% profit difference. However, results show that changes in key factors slightly affect the profit margin, calculating a difference of only 3.7% for particular factor combinations. Combined environmental-friendly agriculture supporting policies are necessary to cover this slight profit difference to promote this biofuel.     

Small-scale production of straight vegetable oil from rapeseed and its use as biofuel in the Spanish territory

Biofuels nowadays are an important topic of study. The most significant point is the availability of bioethanol or biodiesel and their production from different raw materials. It is already known that large-scale production of first-generation biodiesel cannot be seen as an alternative to fossil fuels due to land requirements, competition with food, increase in fertilizer requirements and pressure on tropical forests among others. This fact does not necessarily apply to second-generation biofuels or small-scale niche productions. Straight vegetable oil (SVO) can be used directly in diesel engines with minor modifications. Our proposal is a small-scale SVO production system for self-supply in agricultural machinery. In this paper a model to provide SVO to local farmers in a specific area in Catalonia (Spain) is presented. We also present a discussion about the regulations to be changed in order to make possible the incorporation of SVO as engine fuel in diesel vehicles and a comparative analysis between the emissions of tractors fed with SVO and petrodiesel. Moreover, a quantitative economic analysis of modifying diesel engines and long-term operability costs are shown and a first-run economic analysis comparing the actual crop rotation with the proposed one and some alternatives is studied.     

Requirements for transportation of fast pyrolysis bio-oil in Finland

The purpose of this paper is to discuss the requirements and challenges of pyrolysis oil's transportation in Finland. Pyrolysis oil is a new type of renewable liquid fuel that can be utilised in applications such as heat and electricity production. It has never been transported on a large scale in Finland. Possible options are transport by road, rail and waterway. The most significant requirements in its transportation are created by acidity and high density of pyrolysis oil, which impose requirements for the materials and transport equipment. The study described here shows that constant domestic transportation of pyrolysis oil is most reasonably operated with tank trucks. Rail-based transport may have potential for domestic fixed routes, and transport by water could be utilised in exporting. All transportation methods have limitations and advantages relative to each other. Ultimately, the production site and end-user's locations will determine the most suitable transport method.     

Synthesis of biodiesel from waste vegetable oil with large amounts of free fatty acids using a carbon-based solid acid catalyst

A carbon-based solid acid catalyst was prepared by the sulfonation of carbonized vegetable oil asphalt. This catalyst was employed to simultaneously catalyze esterification and transesterification to synthesis biodiesel when a waste vegetable oil with large amounts of free fatty acids (FFAs) was used as feedstock. The physical and chemical properties of this catalyst were characterized by a variety of techniques. The maximum conversion of triglyceride and FFA reached 80.5 wt.% and 94.8 wt.% after 4.5 h at 220 °C, when using a 16.8 M ratio of methanol to oil and 0.2 wt.% of catalyst to oil. The high catalytic activity and stability of this catalyst was related to its high acid site density (–OH, Brönsted acid sites), hydrophobicity that prevented the hydration of –OH species, hydrophilic functional groups (–SO₃H) that gave improved accessibility of methanol to the triglyceride and FFAs, and large pores that provided more acid sites for the reactants.     

Kinetic modeling and optimization of biomass pyrolysis for bio-oil production

Thermo-kinetic models for biomass pyrolysis were simulated under both isothermal and non-isothermal conditions to predict the optimum parameters for bio-oil production. A comparative study for wood, sewage sludge, and newspaper print pyrolysis was conducted. The models were numerically solved by using the fourth order Runge–Kutta method in Matlab-7. It was also observed that newspaper print acquired least pyrolysis time to attain optimum bio-oil yield followed by wood and sewage sludge under the identical conditions of temperature and heating rate. Thus, at 10 K/min, the optimum pyrolysis time was 21.0, 23.8, and 42.6 min for newspaper print, wood, and sewage sludge, respectively, whereas the maximum bio-oil yield predicted was 68, 52, and 36%, respectively.     

果蔬废弃物与剩余污泥协同厌氧消化特性研究

为了提升污泥的厌氧消化效率,文章从改善原料碳氮比入手,在温度为35℃,挥发性固体(VS)浓度为4%条件下,将果蔬废弃物与污泥按不同VS比例复配,并进行协同厌氧消化产甲烷潜力实验。实验结果表明:在厌氧消化过程中,不同配比实验组的pH值、氨氮浓度和挥发性脂肪酸浓度均在适宜的范围内;不同配比实验组的累积产甲烷量由高到低依次为6∶4,5∶5,4∶6,3∶7,8∶2,7∶3,2∶8,1∶9和9∶1,其分别比纯污泥组提高了516%,485%,430%,360%,335%,330%,290%,144%和-64%。通过Gomperzt修正方程拟合发现,果蔬废弃物与污泥协同厌氧消化的最佳VS配比为6∶4,此时体系的单位VS理论甲烷产率和单位VS最大甲烷日产量分别为114.05mL/g和14.61 mL/(g·d),分别比纯污泥组提高了422%和353%。