Supercritical Methanol Process Research Articles

Separation of waste tantalum capacitors by supercritical methanol: Recovery of high-purity metal tantalum and producing of bisphenol/diphenyl chemicals

With the rapid upgrading of electronic products, a large amount of waste tantalum capacitors (WTC) were generated. The recovery and purification of the WTC attracted widespread interest due to the high-value rare metal tantalum and resin materials. However, the recovery and purification of the WTC was difficult due to the heterogeneous complex composition including metal tantalum, nickel–iron, silver, and organic resins. High-temperature and the potential formation of the hazardous compounds such as dioxins are the main bottleneck of the traditional thermochemical treatment methods for the WTC. In this study, a novel and high-efficiency supercritical methanol (SCM) process was developed for the recovery and purification of tantalum and resins from the WTC based on the low hydrogen bonding numbers and dielectric constant of methanol. The tantalum could be recovered as pure metal tantalum, and the resins were converted into oil by the SCM process. The temperature, time, and solid-to-liquid ratio have significant effect on the conversion ratio of resins. Under the optimal SCM conditions (350 °C, 90 min, and 1:20 g/mL), 97.1% of the external resins of capacitor were converted into oil (99.5%) and gas (0.5%), and the high-purity metal tantalum could be fully recovered. GC–MS and FT-IR analysis showed that the products converted from the resins in the WTC mainly included high level of aromatic derivatives of bisphenol and diphenyl (88.02%), which could be used as fuel or chemical feedstock after proper upgrade. The SCM method is an environmentally friendly process for the recovery and purification of the WTC without any discharge of waste water and off-gas due to that the treatment medium methanol could be recycled. The conversion mechanism of resins in the WTC by the SCM process was proposed.

Techno-economic and profitability analysis of plant for producing biodiesel from fresh vegetable oil and waste frying oil on large-scale

This article attempted to simulate and evaluate the economics of biodiesel synthesis due to the increase in air pollution caused through the use of non-renewable fuels in metropolitan areas and the growing number of diesel vehicles in the country. The purpose of the study istocomparethetechno-economics of two different biodiesel production processes (the alkaline catalysis method of virgin vegetable oil and the non-catalytic supercritical methanol process of waste cooking oil) using Aspen Plus v 8.6 and COMFAR III software. According to the results of the techno-economic study, process II has fewer operating units than process I, but it has lower purity of fatty acid methyl esters and glycerol than process I. Process II also has the largest energy use. Separation units receive a considerable portion of the total equipment costs in process I (49%), which is significantly higher than process II (37%). About 76.05% and 66.28% of the total manufacturing costs were tied to the cost of the feedstock in method I and method II, respectively. In comparison to process I, process II has a greater internal rate of return (27.10%). The prices of biodiesel had the biggest influence on internal rate of return in processes. The prices of methanol and glycerol had the lowest influence on internal rate of return in process I and process II, respectively. Overall, method II appears to be more cost-effective than alkali-catalyzed process I due to decreased manufacturing costs.

Laboratory-Scale Research of Non-Catalyzed Supercritical Alcohol Process for Continuous Biodiesel Production

This work investigates the non-catalyzed supercritical methanol (SCM) process for continuous biodiesel production. The lab-scale setup was designed and used for biodiesel production in the temperature range of 520–650 K and 83–380 bar with an oil-to-methanol molar ratio ranging from 1:5 to 1:45. The experiments were performed in the coiled plug flow tubular reactor. The volumetric flow rate of the methanol/oil ranged from 0.1–10 mL/min. This work examines a new reactor technology involving preheating and pre-mixing of the methanol/oil mixture to reduce setup cost and increase biodiesel yield under the same reaction conditions. Work performed showed that FAME’s yield increased rapidly with temperature and pressure above the methanol critical points (i.e., 513 K and 79.5 bar). The best methyl-ester yield using this reaction technology was 91% at 590 K temperature and 351 bars with an oil-to-methanol ratio of 39 and a 15-min residence time. Furthermore, the kinetics of the free catalyst transesterification process was studied in supercritical methanol under different reaction conditions.

The economic evaluation of establishing a plant for producing biodiesel from edible oil wastes in oil-rich countries: Case study Iran

In this investigation, three chemical processes for biodiesel production evaluated based on the financial standpoint. Due to its strongness and flexibility in economic evaluations, the COMFAR III software utilized for assessing processes. The alkali catalyzed process using virgin vegetable oil (process I), an-acid catalyzed process utilizing waste cooking oil (process II), and two-step supercritical methanol process using waste cooking oil (process III) considered as three deferent chemical processes and financial analyzes applied on all processes. The results of financial evaluation revealed that the process II with 2.992 million $, had the lowest manufacturing prices and with 7.541 million $ net present value would be considered as the most attractive proposal for investment. However, concerning total equipment costs of process III (1.141 million $) and its fixed investment prices (2.158 million $), this process selected as the most economically attractive process. In the next step, to evaluate the impacts of increased sales revenue, reduction in fixed assets, and operating costs on net present value, a sensitivity analysis was carried out. Sensitivity evaluation revealed that alteration in operating costs significantly impacts the net present value, and this significant change is more tangible in the process III.

Simulation process of biodiesel production plant

AbstractThe increasing global demands for fossil fuels have resulted in the release of large quantity of pollutants and reduction of the available resources. Owing to this fact, alternatives to fossil fuels, like biodiesel, are essential for the survival of the existing resources and the decrease of environmental contamination. In the current study, the technical assessment of five continuous biodiesel production processes was designed and simulated with the Aspen Plus v8.6 software. In order to convert virgin vegetable oil (VVO) as well as waste cooking oil (WCO) to biodiesel, alkali‐catalyzed and acid‐catalyzed processes were utilized in the first three processes. In the fourth and fifth processes, the two‐step supercritical methanol method (noncatalytic) and the acid‐catalyzed process were adopted by hexane extraction to transform the WCO to biodiesel. According to the technical assessment, the two‐step supercritical methanol process has the lowest number of operating units; however, it has the lowest purity of FAME (98.47%). The highest purity of glycerol (99.98%) and FAME (99.7%) belong to Processes 3 and 1, respectively. As a result, the homogeneous acid catalytic process of WCO and the two‐step supercritical methanol process are the best choices in terms of technical evaluation among all the examined processes.

Artificial neural network modeling-coupled genetic algorithm optimization of supercritical methanol transesterification of Aegle marmelos oil to biodiesel

This study aims to enhance the transesterification process to convert supercritical methanol (SCM) to biodiesel by applying artificial neural network-coupled genetic algorithm (ANN-GA) optimization. The process parameters selected for ANN-GA optimization were temperature of 230–350 °C, methanol-to-oil molar ratio of 24:1 to 48:1, and time of 5–25 min. The initial set of experiments were designed using the central composite design for ANN modeling. The best ANN topology with an optimal number of hidden neurons was obtained by heuristic analysis of coefficient of determination (R) and mean square error values. The R values (1, 0.99986, 0.9998 and 0.99997) for training, validation, testing, and overall prove the precision of the ANN model. Moreover, hypothesis tests were accomplished to enumerate model fitness. The GA-optimized process conditions for SCM transesterification using ANN as the fitness function were temperature of 325.5 °C, methanol-to-oil molar ratio of 41:1, and time of 23 min. Additionally, relative importance analysis was executed to ascertain the most influential variable on the SCM process. The major fuel properties of Aegle marmelos biodiesel were analyzed and found to comply well with American Society for Testing and Materials (ASTM) D6751 standards.

Comparative life cycle assessment of alternative strategies for energy recovery from used cooking oil

The separate collection of Used Cooking Oil (UCO) is gaining popularity through several countries in Europe. An appropriate management of UCO waste stream leads to substantial benefits. In this study, we analyse two different possibilities of UCO energy reuse: the direct feed to a reciprocating internal combustion engine (ICE) for cogeneration purpose, and the processing to generate biodiesel. Concerning biodiesel production, we analyse four among conventional and innovative technologies, characterised by different type and amount of used chemicals, heat and electricity consumptions and yields. We perform a systematic evaluation of environmental benefits and drawbacks by applying life cycle assessment (LCA) analysis to compare the alternatives.For the impact assessment, two methods are selected: the Global Warming Potential (GWP) and Cumulative Exergy Consumption (CExC). Results related only to the processing phases (i.e. not including yet the avoided effects) show that the recovery of UCO in cogeneration plant has in general lower values in terms of environmental impacts than its employment in biodiesel production.When products and co-products substitution are included, the savings obtained by the substitution of conventional diesel production, in the biodiesel cases, are significantly higher than the avoided effects for electricity and heat in the cogeneration case. In particular, by using the UCO in the biodiesel production processes, the savings vary from 41.6 to 54.6 GJex per tUCO, and from 2270 to 2860 kg CO2eq per tUCO for CExC and GWP, respectively. A particular focus is put on sensitivity and uncertainty analyses. Overall, high uncertainty of final results for process impacts is observed, especially for the supercritical methanol process. Low uncertainty values are evaluated for the avoided effects. Including the uncertain character of the impacts, cogeneration scenario and NaOH catalysed process of biodiesel production result to be the most suitable solutions from the process impacts and avoided effects perspective.

3-49.二段階超臨界メタノール法によるバイオデイーゼル燃料製造技術の最適化((11)水熱・バイオディーゼル,Session 3 バイオマス等)

3-49.二段階超臨界メタノール法によるバイオデイーゼル燃料製造技術の最適化((11)水熱・バイオディーゼル,Session 3 バイオマス等)

A novel recovery method of copper from waste printed circuit boards by supercritical methanol process: Preparation of ultrafine copper materials

In this study, supercritical methanol (SCM) process was successfully used for the preparation of ultrafine copper materials from waste printed circuit boards (PCBs) after nitric acid pretreatment. Waste PCBs were pretreated twice in nitric acid. Sn and Pb were recovered by the first nitric acid pretreatment. The leach liquor with a high concentration of copper ions after the second nitric acid leaching was subjected to SCM process. The mixture of Cu and Cu2O with poor uniformity of particle size was formed due to the effect of ferric iron contained in the leach liquor of waste PCBs, while more uniform and spherical Cu particles with high monodispersity and smaller size could be prepared after the removal of Fe. The size of Cu particles increased obviously with the decline of SCM temperature, and particles became highly aggregated when the reaction temperature decreased to 300°C. The size of Cu particles decreased markedly with the decrease of initial concentration of copper ion in the leach liquor of waste PCBs. It is believed that the process developed in this study is simple and practical for the preparation of ultrafine copper materials from waste PCBs with the aim of recycling these waste resources as a high value-added product.

In-depth study of the transesterification reaction of Pongamia pinnata oil for biodiesel production using catalyst-free supercritical methanol process

Non-edible vegetable oils are promising substitutes for traditional edible food crops used in the synthesis of biodiesel. Among them, Pongamia pinnata oil, also known as Karanja oil, is considered as a good candidate with potential availability of more than 135Mtpa. The present work offers an in-depth study of the transesterification reaction of Karanja oil in supercritical methanol in one-step catalyst-free process. Triglyceride (TG) conversion and the yield of fatty acid methyl esters (FAMEs) are analyzed in the temperature and reaction time ranges of 250–350°C (12–43MPa) and 15–90min, respectively, at an alcohol-to-oil molar ratio of 43:1. This study also covers the evolution of intermediate products such as monoglycerides (MG) and diglycerides (DG) and the thermal decomposition of fatty acid chains for the stated reaction conditions. Optimal reactions conditions were found at 300°C and 90min reaction with almost complete triglyceride conversion. Significant thermal decomposition was observed from 325°C, mainly caused by the degradation of polyunsaturated fatty acid methyl esters. Maximum degree of thermal decomposition of 38% was determined at 350°C after 90min reaction time.

Response surface methodology for the optimization of biofuel production at a low molar ratio of supercritical methanol to used palm olein oil

AbstractA large energy input for preheating and recovering of high excess alcohols used are the main issue in the supercritical methanol (SCM) process. This work demonstrated the production of biofuel from used palm olein oil in SCM using a low methanol to oil molar ratio. The effects of the operating temperature (350–400 °C), methanol to oil molar ratio (9:1–12:1), and reaction time (2–10 min), and their reciprocal interactions were evaluated using a central composite design. The optimum process conditions were determined to be a temperature of 395 °C, methanol to oil molar ratio of 12:1, and reaction time of approximately 9 min through the use of response surface methodology. The modified quadratic regression model demonstrated that the triglyceride conversion (%XTG) and methyl ester content (%FAME) were sensitive to changes in the operating temperature and reaction time, while the effect of the methanol to oil molar ratio was minimal. Under the optimal operating conditions, the predicted values of %XTG and %FAME were 100% and 63.67%, respectively, which were in good agreement with the experimental values. The fuel properties of biofuel obtained from optimal conditions were examined and then compared to American and European standards for biodiesel. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

Biodiesel Production from Green Microalgae Schizochytrium limacinum via in Situ Transesterification

Microalgae are considered as one of the most promising feedstocks for biofuel production because of their environmental and social benefits. However, challenges exist in converting microalgal lipids into algal biofuels because of the unique characteristics of microalgae and the technologies for processing them. This study aims at exploring an alternative sub-/supercritical methanol (subCM/SCM) process technology that combines lipid extraction from whole microalgae and lipid esterification/transesterification in a single step or in situ transesterification. A high lipid content microalgal strain, Schizochytrium limacinum, was used for in situ transesterification in a batch reactor. Temperature (170, 210, 250, and 290 °C), reaction time (30, 60, 90, and 120 min), and lipid/methanol molar ratio (sRatio; 1:50, 1:75, and 1:100) were investigated for their effects on the conversion efficiency. The temperature appeared as a most positive influential factor. Additionally, the operating temperature over 250 °C cau...

Continuous production of biofuel from refined and used palm olein oil with supercritical methanol at a low molar ratio

The high energy consumption and high environmental impact in the supercritical methanol (SCM) process primarily originates from the preheating of reactants and the recovery of excess alcohols. This work demonstrated the synthesis of biofuel using a lowered methanol to oil molar ratio of 12:1, instead of the 40:1–42:1 ratios that are commonly employed in conventional SCM. The apparent density of the reacting mixture was measured and applied to accurately calculate residence times in a continuous reactor. The effects of residence time were considered from 10 to 25min. The results revealed that excessive residence times reduced the ester content, especially for unsaturated esters, in the resulting biofuel. A residence time of 20min was recommended to simultaneously achieve a maximum ester content of 90% and a triglyceride conversion of up to 99%. Used palm olein oil with high free fatty acid (4.56wt.%) can be employed as a feedstock and give a maximum ester content of 80%. In addition, the side reaction between glycerol and methanol at 400°C and 15MPa showed a positive effect in increasing fuel yield by 2%–7%.

Techno-economic analysis of biodiesel production from Jatropha curcas via a supercritical methanol process

This paper presents the conceptual design and economic evaluation of a production of methyl esters (biodiesel) from Jatropha curcas oil (JCO) via a supercritical methanol process with glycerol as a by-product. The process consists of four major units: transesterification (PFR), methanol recovery (FT) and (DC1), recovery of glycerol (DEC), and biodiesel purification (DC2). The material and heat balance are also presented here. A biodiesel production of 40,000tonnes-yr−1 is taken as case study. Biodiesel obtained from supercritical transesterification with Jatropha curcas oil as feedstock resulting in high purity methyl esters (99.96%) with almost pure glycerol (96.49%) obtained as by-product. The biodiesel can be sold at USD 0.78kg−1, while the manufacturing and capital investment costs are in the range of USD 25.39million-year−1 and USD 9.41millionyear−1, respectively. This study proved that biodiesel from JCO is the least expensive with purities comparable to those found in other studies.

Influence of impurities on biodiesel production from Jatropha curcas L. by supercritical methyl acetate process

Generally, water and free fatty acid (FFA) content in oils could cause a serious problem during conventional transesterification such as saponification. Thus, without any pre-treatment, vegetable oil, especially with high FFA content, will be affected. In this study, a non-catalytic supercritical methyl acetate (SCMA) process was utilized to produce biodiesel from Jatropha curcas L. oil. The effects of water and FFA content on the yield of biodiesel were investigated. The results obtained for the effects of water on the yield of biodiesel were compared with the supercritical methanol (SCM) process and conventional catalytic reaction. Results revealed that the catalytic reaction suffers from low yield with the presence of high water content in oil. Meanwhile, the yield of both the SCM and SCMA reactions were found to increase slightly with the increment of water content in the mixture. On the other hand, the results for the effect of FFA on the yield of biodiesel were compared with the SCM reaction. It was found that the presence of FFA has a negligible effect in both the SCMA and SCM reactions. These findings demonstrate that pre-treatment procedures are not necessary in the SCMA process for Jatropha oil which normally contains a high FFA content.

Comparison of direct transesterification of algal biomass under supercritical methanol and microwave irradiation conditions

In this comparative study, direct conversion of algal biomass into biodiesel using supercritical methanol (SCM) and microwave-assisted (MW) transesterification methods was investigated. Wet algal biomass was used as feedstock in the supercritical methanol process and dry algal biomass for the microwave-assisted transesterification. Experimental runs were designed using a response surface methodology and the process parameters such as wet/dry algae to methanol ratio, reaction temperature, reaction time and catalyst concentrations were optimized for both processes. The microwave-assisted approach improves extractions of algae significantly, with a higher efficiency, reduced extractive-transesterification time and increased yield. While the non-catalytic supercritical methanol method produces highly purified extracts (free of harmful solvents and catalyst residues), and reduces energy consumption in separation and purification steps. The algal biodiesel samples from SCM and MW processes were compared using FT-IR and TGA analysis methods to identify the functional group attributions and thermal stability of the biofuel samples, respectively. The transmission electron microscopy (TEM) analysis of algal biomass and lipid extracted algae (LEA) and energy requirements for the two processes are also presented.

Foaming of recycled crosslinked polyethylenes via supercritical decrosslinking reaction

AbstractFoaming of decrosslinked crosslinked polyethylene (DCXLPE) was investigated to assess the feasibility of recycled crosslinked polyethylene for polyolefin foam applications. DCXLPE was recycled from irradiation‐induced crosslinked polyethylene using the supercritical methanol process. As the concentration of crosslinking agents increased, the gel fraction and hardness of the DCXLPE foam sheets increased, while the expansion ratio and cell size decreased. The resulting foam products not only revealed a viable foam structure and properties comparable with those of conventional polyethylene foam from virgin low‐density polyethylene resin but also are expected to open new applications for recycled crosslinked polyolefin via supercritical decrosslinking reaction. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Transesterification of used vegetable oils with a Cs-doped heteropolyacid catalyst in supercritical methanol

In this study, used vegetable oils (VO) were transesterified in supercritical methanol with a Cs-doped heteropolyacid (HPA) catalyst so as to produce biodiesel. The stability of the prepared catalysts was determined by measuring the amount of dissolved heteropoly anions. Cs2.5PW12O40 exhibited the highest stability in supercritical methanol. Kinetic parameters were determined at the initial stage of the reaction to examine the reaction rate of the process. The effects of the reaction parameters, including the molar ratio of methanol to oil, reaction pressure, temperature, and time, on the content of fatty acid methyl esters (FAMEs) were also investigated in order to obtain optimum reaction conditions. The content of FAME reached 92% under the optimum reaction conditions of 260°C, 20MPa, a molar ratio of methanol to oil of 40, and a reaction time of 40min in the presence of 3% catalyst. The results showed that supercritical methanol compensated for the low reaction rate of solid acid catalytic transesterification, while the Cs-doped HPA catalyst mitigated the harsh operation conditions of the supercritical methanol process.

Continuous Production of Biodiesel with Supercritical Methanol: a Simple Compressible Flow Model for Tubular Reactors

From an industrial point of view, the continuous process for biodiesel production with supercritical methanol (SCM) is more appropriate than the batch process. However, lab-scale studies on the continuous process have shown that the maximum conversion always remains slightly lower than that obtained in the batch process. This work proposes a simple compressible flow model to predict the conversion of methanol and oils into methyl esters (ME) along the length of a tubular reactor and further demonstrates the effect of the development of the compressibility factor of the reaction mixture upon the conversion efficiency to ME. The governing equation was derived from a general molar balance in the tubular reactor using transesterification kinetics of refined-bleached-deodorized (RBD) palm oil in SCM coupled with a suitable thermodynamic model with adjusted binary interaction parameters. Vapor-liquid equilibrium data for triolein + methanol, methyl oleate + methanol and glycerol + methanol mixtures were obtained from the literature and then refitted with the thermodynamic model consisting of the Peng-Robinson equation of state and MHV2 mixing rules to find the set of adequate interaction parameters. In order to check the validity of the proposed model, the predicted ME contents were compared with observed values in a lab-scale continuous reactor at various operating temperatures, pressures and methanol to oil molar ratios. The proposed model proved to be adequate for predicting the final conversion to ME for operating temperatures below 320°C, when the thermal degradation reactions of unsaturated fatty acids did not interfere. Our results also illustrate the importance of taking into account the development of the compressibility factor with time and reactor length, since this was shown to be the cause of the lower transesterification reaction rate in the tubular SCM process. The findings in this work could be employed as a knowledgebase to further develop a better model for continuous production of biodiesel with SCM in a tubular reactor.

Process simulation and economic analysis of biodiesel production processes using fresh and waste vegetable oil and supercritical methanol

Three continuous biodiesel processes with production capacity of 40,000 tonne/yr, including a conventional alkali-catalyzed process using both fresh and waste vegetable oil and a supercritical methanol process using waste vegetable oil as the raw material, were simulated in HYSYS. In order to improve the simulation accuracy, the properties of triolein, a model compound of vegetable oil, were re-evaluated. The normal boiling point of triolein was experimentally determined by thermogravimetric analysis and further incorporated in HYSYS simulation, which resulted in improvements in the values of specific heat capacity, mass density, and viscosity. Process economics were analyzed using Aspen In-Plant Cost Estimator. The alkali-catalyzed process using fresh vegetable oil had the lowest total capital investment, but the supercritical process was the most economically feasible overall, providing a lower manufacturing cost and higher net present value and a discounted cash flow rate of return. Sensitivity analyses of net present value were conducted using four parameters including oil feedstock costs, glycerol credit, biodiesel selling prices, and interest rates. Based on the analyses, prediction equations of net present value were developed.