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Techno-economic evaluation of a biogas-based oxidative coupling of methane process for ethylene production
Alberto T. Penteado, Mijin Kim, Hamid R. Godini, Erik Esche, Jens-Uwe Repke
Front. Chem. Sci. Eng.. 2018, 12 (4 ): 598-618.
https://doi.org/10.1007/s11705-018-1752-5
This contribution is a preliminary techno-economic assessment of a biogas-based oxidative coupling of methane (OCM) process. Biogas is frequently utilized as a renewable energy source within small scale combined heat and power plants or as a natural gas substitute. The activation of methane also enables its utilization as a feedstock to produce chemicals. In this sense, the OCM process allows for the direct conversion of methane into ethylene, which is a major building block for the chemical and polymer industries. Biogas resulting from the anaerobic digestion of vinasse, a liquid effluent from bioethanol industry, is treated for contaminant removal and its methane content is converted into ethylene, which is then purified as the main product. The biogas cleaning process is assessed based on literature data, while an experimentally validated simulation model is used to assess the OCM process. A techno-economic evaluation is then performed through a Monte Carlo simulation, wherein uncertain parameters take random values between reasonable bounds. The net present value results positive in 74% of the cases, indicating that the project is profitable under a wide range of scenarios. Some performance improvement opportunities have been identified and highlighted to guide future studies in the topic.
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Methyl acetate–methanol mixture separation by extractive distillation: Economic aspects
Elena Graczová, Branislav Šulgan, Samuel Barabas, Pavol Steltenpohl
Front. Chem. Sci. Eng.. 2018, 12 (4 ): 670-682.
https://doi.org/10.1007/s11705-018-1769-9
Methyl acetate is considered low toxicity volatile solvent produced either as a by-product during methanol carbonylation or via acetic acid esterification with methanol. In both cases, pure methyl acetate has to be isolated from the reaction mixture. Simulation of methyl acetate separation from its mixture with methanol by extraction distillation was carried out in ASPEN+ software. In total three case studies were assumed using two different extraction solvents and two solvent regeneration strategies. In case A, novel extraction solvent 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid, was considered. Raw material separation was achieved in an extraction distillation column while the solvent regeneration was accomplished in a second distillation column in this case. In case study B, the same extraction solvent was used; however, its regeneration was carried out in a single-effect evaporator. Dimethyl sulfoxide was the second extraction solvent selected. Its use in methyl acetate-methanol separation is presented in case study C. As high purity of dimethyl sulfoxide was required for the methyl acetate-methanol azeotrope breaking, its regeneration was carried out in the second distillation column only. To simulate the ternary methyl acetate–methanol–extraction solvent mixtures separation, vapor–liquid equilibrium was predicted based on the NRTL equation. Further, unknown properties of the considered ionic liquid and variation of these properties with temperature were predicted and introduced into the ASPEN+ components properties database. Based on these data, optimum operation parameters of the respective separation equipment were established. In all case studies, the same condition had to be fulfilled, namely minimum methyl acetate content in the distillate from the extraction distillation column of 99.5mol-%. Results of simulations using the respective optimum operation parameters were employed in the economic evaluation of the three separation unit designs studied. It was found that the least energy-demanding design corresponds to the case study B in terms of both capital as well as operation expenses.
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Kinetic-compartmental modelling of potassium-containing cellulose feedstock gasification
Attila Egedy, Lívia Gyurik, Tamás Varga, Jun Zou, Norbert Miskolczi, Haiping Yang
Front. Chem. Sci. Eng.. 2018, 12 (4 ): 708-717.
https://doi.org/10.1007/s11705-018-1767-y
Biomass is of growing interest as a secondary energy source and can be converted to fuels with higher energy density especially by pyrolysis or gasification. Understanding the mechanism and the kinetics of biomass pyrolysis (thermal decomposition) and gasification (conversion of organic material to gases) could be the key to the design of industrial devices capable of processing vast amounts of biomass feedstock. In our work real product components obtained in pyrolysis were took into consideration as well as char and oil as lumped components, and the kinetic constants for a biomass model compound (cellulose) pyrolysis and gasification were identified based on a proposed simplified reaction mechanism within a compartment model structure. A laboratory scale reactor was used for the physical experiments containing consecutive fast pyrolysis and gasification stages using alkali metal (K) containing feedstock, which has a significant effect on the cellulose pyrolysis and gasification. The detailed model was implemented in MATLAB/Simulink environment, and the unknown kinetic parameters were identified based on experimental data. The model was validated based on measurement data, and a good agreement was found. Based on the validated first principle model the optimal parameters were determined as 0.15 mL/min steam flow rate, and 4% K content.
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Extension of pilot tests of cyanide elimination by ozone from blast furnace gas washing water through Aspen Plus® based model
Ismael Matino, Valentina Colla, Teresa A. Branca
Front. Chem. Sci. Eng.. 2018, 12 (4 ): 718-730.
https://doi.org/10.1007/s11705-018-1771-2
For improving wastewater quality, one of the dare of steelworks is reducing cyanide in wastewater of gas washing treatment of blast furnaces. Costs of existing treatments, stringent environmental regulations and changeable composition of water from gas treatment, have led to study how available treatments can be modified and to examine new ones. Ozonation is one of cyanide treatments, tested within a European project. A process model was set up with Aspen Plus® , to assess operating conditions and wastewater distinctive characteristics and to demonstrate treatment robustness. Process was modeled by theoretical reactors, taking into account all more affecting reactions. A genetic algorithm was exploited to find kinetic parameters of these reactions. After validation, the model was used to analyse scenarios, by considering also real contexts. Pilot tests were extended, process knowledge was enhanced and suggestions were obtained. To promote cyanide removal with ozone, temperature and pH values were 30°C and 10, respectively. With an ozone (mg/h)/water (L/h) ratio of 100 mg/L, batch mode ensure reaching cyanide regulation limit (0.2 mg/L) after maximum 4.5 h, if initial amount was less than 20 mg/L. Higher removal was obtained than in continuous mode due to constraints related to this last run. Higher wastewater contamination needed further time and more ozone.
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Process synthesis with simultaneous consideration of inherent safety-inherent risk footprint
Andreja Nemet, Jiří J. Klemeš, Zdravko Kravanja
Front. Chem. Sci. Eng.. 2018, 12 (4 ): 745-762.
https://doi.org/10.1007/s11705-018-1779-7
Process plants should be designed to be economically viable and environmentally friendly, while also being operable and maintainable during process implementation. The safety of processes is among the most important considerations in obtaining results that are more acceptably realistic, as it is linked to the availability and reliability of the process. Inherent safety can effectively be enhanced in the early stages of the design, when the main decisions on process design are made. The aim of this study is to enhance and select the appropriate risk assessment method and to incorporate it into process synthesis, using a mathematical programming approach. A mixed-integer, nonlinear programming (MINLP) model was used for the synthesis of a methanol production process, considering risk assessment during the synthesis. Risk assessment is performed simultaneously with the MINLP process synthesis, where the risk is determined either for the whole process as overall risk, or on a per unit-of-a-product basis. For the latter, a new measurement is proposed: the inherent risk footprint. The results of a case study led to two main conclusions: (i) Significantly safer designs can be obtained at negligible economic expense, and (ii) at higher production capacities, a lower inherent risk footprint can be achieved. The results also indicate that designs obtained using this method can have significantly increased inherent safety, while remaining economically viable.
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Efficient production of D-1,2,4-butanetriol from D-xylose by engineered Escherichia coli whole-cell biocatalysts
Shewei Hu, Qian Gao, Xin Wang, Jianming Yang, Nana Xu, Kequan Chen, Sheng Xu, Pingkai Ouyang
Front. Chem. Sci. Eng.. 2018, 12 (4 ): 772-779.
https://doi.org/10.1007/s11705-018-1731-x
We have developed a whole-cell bioconversion system for the production of D-1,2,4-butanetriol (BT) from renewable biomass. A plasmid pETduet-xylB-yjhG- T7-adhP- T7-mdlC was constructed and transformed to Escherichia coli BL21(DE3) to obtain the whole cells of E. coli BL21-XYMA capable of bioconversion D-xylose to BT. Then, the factors including carbon sources, nitrogen sources, metal ions, and culture conditions (pH, temperature, IPTG) were identified, and their effects on the whole-cell activity for BT production were investigated. To obtain the highest whole-cell activity, the optimal cultivation parameters are: 15 g·L− 1 yeast extract, 5 g·L− 1 sucrose, 3 g·L− 1 KH2 PO4 , 5 g·L− 1 NaCl, 3 g·L− 1 NH4 Cl, 0.25 g·L− 1 MgSO4 ∙7H2 O and 1 mL·L− 1 the mixture of trace elements. With the optimized whole cells of E. coli BL21-XYMA , 60 g·L− 1 of xylose was converted to 28 g·L− 1 BT with a molar yield of 66.0%, which is higher than those reported in the biotechnological system.
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Biomimetic mineralization and cytocompatibility of nanorod hydroxyapatite/graphene oxide composites
Peizhen Duan, Juan Shen, Guohong Zou, Xu Xia, Bo Jin
Front. Chem. Sci. Eng.. 2018, 12 (4 ): 798-805.
https://doi.org/10.1007/s11705-018-1708-9
Nanorod hydroxyapatite (NRHA)/graphene oxide (GO) composites with weight ratios of 0.4, 1.5, and 5 have been fabricated by a facile ultrasonic-assisted method at room temperature and atmospheric pressure. The chemical structure properties and morphology of the composites were characterized by field emission source scanning electron microscope, X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The results indicate that the NRHA/GO composites have an irregular surface with different degree wrinkles and are stable, and NRHA are well combined with GO. In addition, the biomimetic mineralization mechanism of hydroxyapatite on the NRHA/GO composites in simulated body fluid (SBF) is presented. The presence of a bone-like apatite layer on the composite surface indicate that the NRHA/GO composites facilitate the nucleation and growth of hydroxyapatite crystals in SBF for biomimetic mineralization. Moreover, the NRHA-1.5/GO composite and pure GO were cultured with MC3T3-E1 cells to investigate the proliferation and adhesion of cells. In vitro cytocompatibility evaluation demonstrated that the NRHA/GO composite can act as a good template for the growth and adhesion of cells. Therefore, the NRHA/GO composite could be applied as a GO-based, free-template, non-toxic, and bioactive composite to substitute for a damaged or defect bone.
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Greenhouse gas emissions from thermal treatment of non-recyclable municipal waste
Tomáš Ferdan, Martin Pavlas, Vlastimír Nevrlý, Radovan Šomplák, Petr Stehlík
Front. Chem. Sci. Eng.. 2018, 12 (4 ): 815-831.
https://doi.org/10.1007/s11705-018-1761-4
This paper analyses factors affecting the production of greenhouse gases from the treatment of residual municipal waste. The analysis is conducted so that the environmentally-friendly decision-making criteria may be later implemented into an optimisation task, which allocates waste treatment capacities. A simplified method of life cycle assessment is applied to describe environmental impact of the allocation. Global warming potential (GWP) is employed as a unit to quantify greenhouse gases (GHG) emissions. The objective is to identify the environmental burdens and credits measured by GWP for the three fundamental methods for treatment of residual waste unsuitable for material recovery. The three methods are waste-to-energy (WTE), landfilling and mechanical-biological treatment (MBT) with subsequent utilization of refuse-derived fuel. The composition of the waste itself and content of fossil-derived carbon and biogenic carbon are important parameters to identify amounts of GHG. In case of WTE, subsequent use of the energy, e.g., in district heating systems in case of heat, is another important parameter to be considered. GWP function dependant on WTE capacity is introduced. The conclusion of this paper provides an assessment of the potential benefits of the results in optimisation tasks for the planning of overall strategy in waste management.
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Research and development of hydrocracking catalysts and technologies in China
Chong Peng, Yanze Du, Xiang Feng, Yongkang Hu, Xiangchen Fang
Front. Chem. Sci. Eng.. 2018, 12 (4 ): 867-877.
https://doi.org/10.1007/s11705-018-1768-x
Hydrocracking of petroleum feedstock represents a compelling route for the production of industrial clean fuels, which has triggered the continuous research and development of core technology related areas such as catalysts, reaction engineering and engineering design. This review particularly focuses on the research and development of catalysts and catalytic processes for hydrocracking of petroleum feedstock in China. Hydroprocessing technologies of China keep pace with the up-to-date progress of the world, and some of the technologies have achieved leading role in the world. It is noted that China Petroleum and Chemical Corporation has a full range of hydroprocessing technologies and provides corresponding “tailor-made” catalysts. Through the efforts of several generations, 20 categories of the catalysts including more than 60 brands have been developed, among which more than 40 brands have been successfully applied for more than 130 times. Importantly, the pivotal technical improvements including the deep drawing vacuum gas-oil (VGO) and de-asphalting oil hydrocracking technology to improve material adaptability, the high value-added hydrogenation technology to convert high aromatic diesel conversion to naphtha, the hydrocracking technology using VGO-catalytic diesel blends, the Fushun Research Institute of Petroleum and Petrochemicals’ diesel to gasoline and diesel hydrocracking technologies, and the Sheer hydrocracking technology to reduce energy are reviewed.
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26 articles