Feasibility study of a thermally coupled reactive distillation process for biodiesel production

Biodiesel fuel represents an interesting alternative as a clean and renewable substitute of fossil fuels. A typical biodiesel production process involves the use of a catalyst, which implies high energy consumptions for the separation of the catalyst and the by-products of the reaction, including those of undesirable side reactions (such as the saponification reaction). A recently proposed process involves the use of short-chain alcohols at supercritical conditions, avoiding the use of a catalyst and the occurrence of the saponification reaction. This process requires fewer pieces of equipment than the conventional one, but its high energy requirements and the need of special materials that support the reaction conditions makes the main product, biodiesel fuel, more expensive than petroleum diesel. In this work, a modification of the supercritical process for the production of biodiesel fuel is proposed. Two alternatives are proposed. The process involves the use of either reactive distillation or thermally coupled reactive distillation. Simulations have been carried out by using the Aspen One™ process simulator to demonstrate the feasibility of such alternatives to produce biodiesel with methanol at high pressure conditions. A design method for the thermally coupled system is also proposed. Both systems have been tested and the results indicate favorable energy performance when compared to the original scheme. Furthermore, the thermally coupled system shows lower energy consumptions than the reactive distillation column.     

Comparison of membrane extraction with traditional extraction methods for biodiesel production

Three traditional methods for the refining step in biodiesel production were compared: (i) washing with distilled water; (ii) washing with acid (HCl); and (3) dissolving and extracting in a solvent (hexane or petroleum ether) and then washing with distilled water. Biodiesel with a high purity (97.5%) could be obtained by all three methods, but serious emulsification occurred during the refining processes, which led to high refining losses. A novel refining method was developed by using hollow fiber membrane extraction, and polysulfone was selected as the most suitable membrane. This process effectively avoided emulsification during refining and decreased the refining loss. The purity of the biodiesel obtained was about 99%; and other properties, such as density, kinematic viscosity, water content, and acid value, conformed to the standards.     

An integrated reactive distillation process for biodiesel production

An integrated reactive distillation process for biodiesel production is proposed. The reactive separation process consists of two coupled reactive distillation columns (RDCs) considering the kinetically controlled reactions of esterification of the fatty acids (FFA) and the transesterification of glycerides with methanol, respectively. The conceptual design of the reactive distillation columns was performed through the construction of reactive residue curve maps in terms of elements. The design of the esterification reactive distillation column consisted of one reactive zone loaded with Amberlyst 15 catalyst and for the transesterification reactive column two reactive zones loaded with MgO were used. Intensive simulation of the integrated reactive process considering the complex kinetic expressions and the PC-SAFT EOS was performed using the computational environment of Aspen Plus. The final integrated RD process was able to handle more than 1% wt of fatty acid contents in the vegetable oil. However, results showed that the amount of fatty acids in the vegetable oil feed plays a key role on the performance (energy cost, catalyst load, methanol flow rate) of the integrated esterification–transesterification reactive distillation process.     

Parametric study of biodiesel production from used soybean oil

Biodiesel, an alternative diesel fuel derived from vegetable oil, animal fat, or waste vegetable oil (WVO), is obtained by reacting the oil or fat with an alcohol (transesterification) in the presence of a basic catalyst to produce the corresponding mono‐alkyl esters. In this work, the effect of the catalyst KOH‐to‐WVO ratio, ethanol concentration, and time of reaction on the biodiesel yield were investigated. The transesterification reaction was performed at a constant temperature (35 °C) in order to minimize the cost of heating and ethanol evaporation. A 2³ complete factorial design on biodiesel yield (Y) was performed using low and high levels of operating variables: KOH concentration (9–14 g/L), ethanol concentration (30–40 vol‐%) and time (30–40 min). The complete factorial model that can be used to fit the data was determined. The model shows that interactions exist among the parameters and that the parameters, or factors, do not operate independently on the response (biodiesel yield). The highest yield was obtained in the first 30 min of reaction time. The results indicate that the highest yield was 78.5 vol‐% using a KOH‐to‐WVO ratio of 12 g/L and 30 vol‐% ethanol. The ASTM tests indicate that the biodiesel properties are within the biodiesel standard limits.     

Kalsilite based heterogeneous catalyst for biodiesel production

Kalsilite (KAlSiO₄) was used as a heterogeneous catalyst for transesterification of soybean oil with methanol to biodiesel. Kalsilite showed relatively low catalytic activity for transesterification reaction. The catalytic activity of this catalyst was significantly enhanced by introducing a small amount of lithium nitrate by the impregnation method. A biodiesel yield of 100% and a kinematic viscosity of 3.84 cSt were achieved at a mild temperature of only 120 °C over this lithium modified kalsilite catalyst (2.3 wt.% Li).     

Economic and ecological aspects of biodiesel production over homogeneous and heterogeneous catalysts

The objective of this paper is to highlight the economic and ecological differences of biodiesel production over homogeneous and heterogeneous catalysts in large-scale industrial plants. Comparative economic assessment of the two processes revealed the advantage of the heterogeneous process in terms of higher yield of biodiesel and higher purity of glycerine, lower cost of catalyst and maintenance, with an estimated cumulative impact on the reduction of the operating cost of US$59 per tonne of biodiesel, relative to the homogeneous process. The biggest challenge for its economic competitiveness is its higher energy consumption. The analysis showed that if the energy costs are below US$85 per tonne of biodiesel, the heterogeneous process can be economically viable. The environmental benefits of the heterogeneous process include absence of strong acids and of energy intensive and waste generating glycerine purification step. However, its application would contribute to depletion of fossil energy resources and higher emission of greenhouse gases due to higher energy and methanol consumption.     

Life cycle analysis of biodiesel production

Biodiesel has attracted considerable attention as a renewable, biodegradable, and nontoxic fuel and can contribute to solving the energy problems, significantly reducing the emission of gases which cause global warming.The first stage of this work was to simulate different alternative processes for producing biodiesel. The method used for the production of biodiesel is the transesterification of vegetable oils with an alcohol in the presence of a catalyst. The raw materials used were palm oils and waste cooking oil.The second stage was a life cycle analysis for all alternatives under study, followed by an economic analysis for the alternatives that present minor impacts and which are more promising from an economic point of view. Finally, we proceeded to compare the different alternatives from both the point of view of life cycle and economic analysis.The feasibility of all processes was proven and the biodiesel obtained had good specifications.From the standpoint of life cycle analysis, the best alternative was the process of alkaline catalysis with acid pre-treatment for waste cooking oil.The economic analysis was done to the previous mentioned process and to the process that uses raw virgin oils, methanol, and sodium hydroxide. This process has lower investment costs but the process of alkaline catalysis with acid pre-treatment, whose main raw material is waste oil, is much more profitable and has less environmental impacts.     

壳聚糖生产的技术经济论证

介绍了壳聚糖的市场动态,生产方法、工艺特点和技术指标,对３００ｔ／ａ生产线进行了技术经济分析。     

Extraction,transesterification and process control in biodiesel production from Jatropha curcas

Biodiesel has gained worldwide popularity as an alternative energy source due to its renewable, non‐toxic, biodegradable and non‐flammable properties. It also has low emission profiles and is environmentally beneficial. Biodiesel can be used either in pure form or blended with conventional petrodiesel in automobiles without any major engine modifications. Various non‐edible and edible oils can be used for the preparation of biodiesel. With no competition with food uses, the use of non‐edible oils as alternative source for engine fuel will be important. Among the non‐edible oils, such as Pongamia, Argemone and Castor, Jatropha curcas has tremendous potential for biodiesel production. J. curcas, growing mainly in tropical and sub‐tropical climates across the developing world, is a multipurpose species with many attributes and considerable potentials. In this article, we review the oil extraction and characterization, the role of different catalysts on transesterification, the current state‐of‐the‐art in biodiesel production, the process control and future potential improvement of biodiesel production from J. curcas.     

Model-based optimisation of biodiesel production from microalgae

This work presents a superstructure-based optimisation model to optimise the microalgae to biodiesel production flowsheet for the minimum net annualised life cycle cost (ALCC) of biodiesel. The model includes the important processing steps of converting microalgae into biodiesel, viz. microalgae growth, harvesting, lipid extraction, and transesterification of lipid. Different options to perform these steps are considered. The mass and volumetric balance for each process and equipment, and the equipment capacity limitations constitute the important model constraints. The decision variables include growth duration, medium, as well as the techniques and specifications to be followed in each of the downstream steps. The mixed integer linear programming model was applied to a case study of producing 30,000 kg/d biodiesel from Chlorella. The minimum ALCC was US $ 13.286/l for the flowsheet and equipment details recommended by the model. Sensitivity analysis showed that lipid extraction was the most crucial step in the flowsheet.     

Techno-economic analysis of a biodiesel production process from vegetable oils

Biodiesel, which is defined as the monoalkyl esters of long chain fatty acids derived from a renewable lipid feedstock, has received considerable attention worldwide as a medium-term alternative to diesel fuel obtained from petroleum. Biodiesel can be produced by the transesterification of vegetable oils or animal fats using short-chain alcohols in the presence of a suitable catalyst and glycerol is the only byproduct obtained in significant quantities. In this work a techno-economic analysis of a process that produces biodiesel from vegetable oils is presented with the aim to investigate the dependence of the critical profitability indicators on the production capacity.     

Optimization of the transesterification reaction in biodiesel production

In this paper response surface methodology (RSM) was used to study the transesterification reaction of rapeseed oil for biodiesel production. The three main factors that drive the conversion of triglycerides into fatty acid methyl esters (FAME) were studied according to a full factorial design at two levels. These factors were catalyst concentration (KOH), temperature and reaction time. The range investigated for each factor was selected taking into account the process of Fox Petroli S.p.A. Analysis of variance (ANOVA) was used to determine the significance of the factors and their interactions which primarily affect the first of the two transesterification stages. This analysis evidenced the best operating conditions of the first transesterification reaction performed at Fox’s plant: KOH concentration 0.6% w/w, temperature 50 °C and reaction time 90 min with a CH₃OH to KOH ratio equal to 60. Three empirical models were derived to correlate the experimental results, suitable to predict the behavior of triglyceride, diglyceride and monoglyceride concentration. These models showed a good agreement with the experimental results, demonstrating that this methodology may be useful for industrial process optimization.     

An overview of solid base heterogeneous catalysts for biodiesel production

The alcoholysis process requires high activity catalysts for biodiesel production. Heterogeneous catalysts have been proven to possess highly active nature and are environment-friendly. The present article emphasizes on various types of solid base catalysts that have been used in the recent past for the production of biodiesel by transesterification of oils. The parameters and conditions affecting the transesterification reaction and biodiesel yield have also been mentioned in the article. Heterogeneous catalysts have the capability to be recycled for many runs in the process without greatly abating the biodiesel yield. Also, such catalysts possess noncorrosive nature, thus making the biodiesel safe to be used in engine without any damage. The exploitation of waste materials as catalysts would reduce the overall production cost of biodiesel. Calcium-based catalysts in the reviewed literature have shown promising outcomes for the future use and would make the process economical for large-scale industrial applications.     

Calcined sodium silicate as solid base catalyst for biodiesel production

This paper examined the use of calcined sodium silicate as a novel solid base catalyst in the transesterification of soybean oil with methanol. The calcined sodium silicate was characterized by DTA-TG, Hammett indicator method, XRD, SEM, BET, IR and FT-IR. It catalyzed the transesterification of soybean oil to biodiesel with a yield of almost 100% under the following conditions: sodium silicate of 3.0 wt.%, a molar ratio of methanol/oil of 7.5:1, reaction time of 60 min, reaction temperature of 60 °C, and stirring rate of 250 rpm. The oil containing 4.0 wt.% water or 2.5 wt.% FFA could also be transesterified by using this catalyst. The catalyst can be reused for at least 5 cycles without loss of activity.     

Effects of process variables for biodiesel production by transesterification

In this study, biodiesel production from various vegetable oils by transesterification was studied, to determine the optimum conditions. Experiments were carried out by using different kinds of catalysts (sodium hydroxide, potassium hydroxide, barium hydroxide, pyrolitic coke and wood ash) and feedstocks (corn oil, sunflower oil, soybean oil, olive pomace oil and cottonseed oil) at 65 °C and an agitation speed of 1000 rpm. The neutralization step with controlled pH was performed by treatment with phosphoric acid. An experimental design was used to evaluate the effects of the parameters such as types of vegetable oils, kinds of catalysts, reaction time, alcohol/oil volumetric ratio and amount of catalyst, on the methyl ester conversion. Using response surface methodology, a quadratic polynomial equation was obtained by multiple regression analysis. It was found that catalyst concentration was the most effective parameter. Sodium hydroxide and potassium hydroxide exhibited a superior catalytic behavior, whereas pyrolitic coke and wood ash had to be used in excess amount or for prolonged reaction times. Moreover, the properties such as viscosity, density, calorific value, acid value, and refractive index of the biodiesel were measured. The tri‐, di‐, monoacylglycerols and glycerol residuals in the methyl esters produced were also quantified by GC analysis.     

Activity of solid catalysts for biodiesel production: A review

Heterogeneous catalysts are promising for the transesterification reaction of vegetable oils to produce biodiesel. Unlike homogeneous, heterogeneous catalysts are environmentally benign and could be operated in continuous processes. Moreover they can be reused and regenerated. However a high molar ratio of alcohol to oil, large amount of catalyst and high temperature and pressure are required when utilizing heterogeneous catalyst to produce biodiesel. In this paper, the catalytic activity of several solid base and acid catalysts, particularly metal oxides and supported metal oxides, was reviewed. Solid acid catalysts were able to do transesterification and esterification reactions simultaneously and convert oils with high amount of FFA (Free Fatty Acids). However, the reaction rate in the presence of solid base catalysts was faster. The catalyst efficiency depended on several factors such as specific surface area, pore size, pore volume and active site concentration.