Two-step curing processes for coating application

Two novel two-stage cure processes will be described, both involving oxetane chemistry. In both processes, the two consecutive cure processes are completely separated from one another.     

Applications of process synthesis: Moving from conventional chemical processes towards biorefinery processes

Concerns about diminishing petroleum reserves, enhanced worldwide demand for fuels and fluctuations in the global oil market, together with climate change and national security have promoted many initiatives for exploring alternative, non-petroleum based processes. Among these initiatives, biorefinery processes for converting biomass derived carbohydrates into transportation fuels and chemicals are now gaining more and more attention from both academia and industry. Process synthesis, which has played a vital role for the development, design and operation of (petro) chemical processes, can be predicted to play a significant role in the design and commercialization of sustainable and cost-effective biorefinery processes. The main objective of this perspective paper is to elucidate the potential opportunities that biorenewables processing offers to optimal synthesis; challenges and future directions in this field are also concisely discussed. An attempt is made with this perspective to stimulate more and more efforts to optimally synthesize and design biorenewable conversion process to accelerate the commercialization of the biorefinery technology and further reduce the heavily reliance on petroleum-derive fuels.     

化工过程反应路径综合方法的研究进展

反应路径综合是过程综合的核心,对减小过程的环境影响、提高过程安全性等起到关键作用。本文介绍了已有反应路径综合方法,并着重阐述了考虑环境因素和安全因素的综合方法的研究进展,重点阐明了这些方法的实现手段以及实例应用情况,分析了它们的优点和不足。对几种具有代表性的反应路径综合方法的特色以及存在的问题进行了评价,得到反应路径综合研究的重点主要有以下3方面:基于反应路径综合的成熟方法,寻求集成本质安全的策略方法将有利于实现反应路径的本质安全;应用多目标优化方法获取反应路径综合的多目标最优解是重要的研究方向之一;着眼于全局过程系统,注重环境影响最小化的反应路径综合的实现和应用研究具有重要现实意义。     

两步酶法合成阿糖鸟苷

The chemical synthesis of Guanine arabinoside （ara-G） is extremely complex, time-consuming, and seriously polluted. A two-step enzymatic synthesis process was developed to acquire ara-G easily. 2,6-Diaminopurine arabinoside （ara-DA） was first synthesized with purine nucleoside phosphorylase and pyrimidine nucleoside phosphorylase produced by Enterobacter aerogenes DGW-07. The conversion yield of ara-DA could reach above 90% when the reaction liquid contained 30 mmol·L^-1 uracil arabinoside as arabinose donor, 10 mmol·L^- 1 2,6-diaminopurine as arabinose acceptor in pH 7.0 20 mmol·L^-1 phosphate buffer, and reacted at 60℃ for 48h. Then, ara-DA was effectively transformed into ara-G with adenylate deaminase produced by Aspergillus oryzae DAW-01. The total process had no complex separation and purification.     

Systematic methods and tools for design of sustainable chemical processes for CO2 utilization

A systematic computer-aided framework for sustainable process design is presented together with its application to the synthesis and generation of processing networks for dimethyl carbonate (DMC) production with CO₂ utilization. The framework integrated with various methods, tools, algorithms and databases is based on a combined process synthesis–design–intensification method. The method consists of three stages. The synthesis-stage involves superstructure based optimization to identify promising networks that convert a given set of raw materials to a desired set of products. The design-stage involves selection and analysis of the identified networks as a base case design in terms of operational feasibility, economics, life cycle assessment factors and sustainability measures, which are employed to establish targets for improvement in the next-stage. The innovation-stage involves generation and screening of the more sustainable alternatives through a phenomena-based process intensification method. Applications of the framework are highlighted for the DMC production process.     

Two-step synthesis process for high-entropy diboride powders

High-entropy diboride powders were produced by a two-step synthesis process consisting of boro/carbothermal reduction followed by solid solution formation. Nominally phase-pure (Hf,Zr,Ti,Ta,Nb)B₂ in a single-phase hexagonal structure had an average particle size of just over 400 nm and contained 0.3 wt% carbon and 0.3 wt% oxygen. The fine particle size was due to the use of high-energy ball milling prior to boro/carbothermal reduction, which led to a relatively low synthesis temperature of 1650°C. Oxygen and carbon contents were minimized by completion of the boro/carbothermal reduction reactions under vacuum. This is the first report of synthesis of a nominally phase pure high-entropy diboride powder from oxides using a two-step process.     

Physical–chemical model of processes at detonation synthesis of nanodiamonds

This article presents a principally new physical–chemical model of nanodiamond formation at explosion, which describes adequately all the existing experimental data on detonation synthesis of diamonds. According to this model, the detonation wave performs activation rapidly; then the reaction mixture composition keeps varying. In the diagram C – H – O this process results in continual motion of the point imaging the reaction mixture composition. The ratio of the diamond phase amount to the condensed carbon quantity in the explosion products is defined by the width of the section this point passes over in the diamond formation zone. Motion of the point in the area below the line H – CO results in decrease of the condensed carbon (CC) amount. Diamonds are formed by the free-radical mechanism in the unloading wave.     

The synthesis of nearly optimal on-off controllers with application to chemical processes

A new technique is presented for designing a set of on-off controllers for processes which can be approximated by linear-lumped parameter models of any order. The design is based on the minimization of a quadratic function of the process outputs. Each higher member of the set of systems approaches optimal control ever more closely. Our major concern, however, is with the lowest member of the set which is implemented by using only a relay and a simple summing device. Several analog computer examples are presented using this control scheme. In all cases, the system response is excellent from both quantitative and qualitative viewpoints.

One of the examples presented is the control of a simulated six stage liquid—liquid extraction unit. Here, the lowest level control is shown to outperform an experimentally tuned standard three-mode type of control as well as a control strategy based on dynamic programming which was developed for the same process by a previous investigator.     

Exergy analysis of energy‐intensive production processes: advancing towards a sustainable chemical industry

Exergy analysis is becoming a very powerful strategy to evaluate the real efficiency of a process. Its application in the chemical industry is still at an early stage but many interesting remarks can be obtained from the recent research in the most energy intensive processes of the chemical industry: the production of chemicals, the cement industry, the paper industry and, the iron and steel industry. The present review analyzes the opportunities and challenges in those sectors by considering exergy analyses as the first required step (although not sufficient) to advance towards a more sustainable chemical industry. Social, environmental and economic factors play a role in the critical evaluation of a process and exergy could be considered as the property that joins together those three cores of sustainability. © 2014 Society of Chemical Industry     

Synthesis of sustainable integrated biorefinery via reaction pathway synthesis: Economic,incremental enviromental burden and energy assessment with multiobjective optimization

With the increasing attention toward sustainable development, biomass has been identified as one of the most promising sources of renewable energy. To convert biomass into value‐added products and energy, an integrated processing facility, known as an integrated biorefinery is needed. To date, various biomass conversion systems such as gasification, pyrolysis, anaerobic digestion and fermentation are well established. Due to a large number of technologies available, systematic synthesis of a sustainable integrated biorefinery which simultaneously considers economic performance, environmental impact, and energy requirement is a challenging task. To address this issue, multiobjective optimization approaches are used in this work to synthesize a sustainable integrated biorefinery. In addition, a novel approach (incremental environmental burden) to assess the environmental impact for an integrated biorefinery is presented. To illustrate the proposed approach, a palm‐based biomass case study is solved. © 2014 American Institute of Chemical Engineers AIChE J, 61: 132–146, 2015     

Sustainable biopolymer synthesis via superstructure and multiobjective optimization

Sustainable polymers derived from biomass have great potential to replace petrochemical based polymers and fulfill the ever‐increasing market demand. To facilitate their industrialization, in this research, a comprehensive superstructure reaction network comprising a large number of reaction pathways from biomass to both commercialized and newly proposed polymers is constructed. To consider economic performance and environmental impact simultaneously, both process profit and green chemistry metrics are embedded into the multiobjective optimization framework, and MINLP is used to enable the effective selection of promising biopolymer candidates. Through this proposed approach, this study identifies the best biopolymer candidates and their most profitable and environmentally friendly synthesis routes under different scenarios. Moreover, the stability of optimization results regarding the price of raw materials and polymers and the effect of process scale on the investment cost are discussed in detail. These results, therefore, pave the way for future research on the production of sustainable biopolymers. © 2017 American Institute of Chemical Engineers AIChE J, 63: 91–103, 2018     

Imprinted membranes for sustainable separation processes

The rapid industrial growth and the necessity of recovering and recycling raw materials increased the interest in the production of highly selective and efficient separation tools. In this perspective, a relevant input was given by the membrane-based technology and the production of imprinted membranes, which possess specific recognition properties at molecular and ionic level, offers the possibility of developing sustainable and green processes. Furthermore, the integration of imprinted membranes with traditional or membrane-based approaches is a promising strategy in the logic of process intensification, which means the combination of different operations in a single apparatus. This work discusses the concept and separation mechanisms of imprinted membranes. Furthermore, it presents an overview of their application in organic solvent nanofiltration, for the removal of toxic agents and recovery solvent, as well as valuable compounds. The recent advances in water treatment, such as pesticide removal and recovery of metal ions, are also discussed. Finally, potential applications of imprinted membranes in hybrid processes are highlighted, and a look into the future of membrane separations for water treatment and recovery of critical raw materials is offered.     

A thermodynamic approach to the synthesis of heat integration systems in chemical processes

Starting with no heat integration, from initial structure for a chemical processing system, a series of modified systems with improved heat utilization can be evolutionally developed by a computer aided method, on the thermodynamic available energy concept. An illustrative example shows that processing systems with high degree of efficient energy utilization have been generated.     

Two-step continuous synthesis of tetraethylthiuram disulfide in microstructured reactors

We present two-step continuous synthesis of tetraethyl thiuram disulfide using microstructured reactors, starting with the formation of N, N-diethyldithiocarbamic acid from carbon disulfide and diethylamine in the first mi- crostructured reactor, and the oxidation of N, N-diethyldithiocarbamic acid by hydrogen peroxide in the second one. We studied the effects of reaction temperature, LHSV and total flow rate on the yield of the product. In the first microstructured reactor assembled with an HPIMM micromixer and a stainless steel capillary as the delay loop, the yield of N, N-diethyldithiocarbamic acid reached 96.3% in the 40 wt% diethylamine ethanol solution under reaction conditions of the CS₂/(C₂H₅)₂NH molar ratio of 1.1: 1, total flow rate of 4 mL/min, LHSV of 42.4 h⁻¹, and reaction temperature of 25 °C. Consequently, the obtained N, N-diethyldithiocarbamic acid solution was reacted with H₂O₂ solution in another microstructured reactor assembled with SIMM-V2 and a PTFE capillary as the delay loop, the yield of the high purity tetraethylthiuram disulfide reached 89.3% under the optimized reaction conditions.     

Two-step hydrothermal synthesis of Ru-Sn oxide composites for electrochemical supercapacitors

A two-step hydrothermal process was developed to synthesize hydrous 30RuO₂-70SnO₂ composites with much better capacitive performances than those fabricated through the normal hydrothermal process, co-annealing method, or modified sol-gel procedure. A very high specific capacitance of RuO₂ (C_S,Ru), ca. 1150 F g⁻¹, was obtained when this composite was synthesized via this two-step hydrothermal process with annealing in air at 150 °C for 2 h. The voltammetric currents of this annealed composite were found to be quasi-linearly proportional to the scan rate of CV (up to 500 mV s⁻¹), demonstrating its excellent power property. From Raman, UV-vis spectroscopic and TEM analyses, the reduction in mean particulate size is clearly found for this two-step oxide composite, attributable to the co-precipitation of (Ru_δSn_1−δ)O₂·xH₂O onto partially dissolved SnO₂·xH₂O and the formation of (Ru_δSn_1−δ)O₂·xH₂O crystallites in the second step. This effect significantly promotes the utilization of RuO₂ (i.e., very high C_S,Ru). The excellent capacitive performances, very similar to that of RuO₂·xH₂O, suggest the deposition of RuO₂-enriched (Ru_δSn_1−δ)O₂·xH₂O onto SnO₂·xH₂O seeds as well as the individual formation of (Ru_δSn_1−δ)O₂·xH₂O crystallites in the second hydrothermal step.     

Two-step enzymatic reaction for the synthesis of pure structured triacylglycerides

Structured triacylglycerides with medium-chain fatty acids (caprylic acid) in sn1- and sn3-positions and a long-chain unsaturated fatty acid (oleic or linoleic acid) in the sn2-position of glycerol (MLM) were synthesized by lipase catalysis in a two-step process. First, pure 2-monoacylglycerides (2-MG) were synthesized by alcoholysis of triacylglycerides (triolein, trilinolein, or peanut oil) in organic solvents with 1,3-regiospecific lipases (from Rhizomucor miehei, Rhizopus delemar, and Rhizopus javanicus). The 2-MG were purified by crystallization and obtained in up to 71.8% yield. These 2-MG were esterified in a second reaction with caprylic acid in n-hexane to form almost pure MLM. For 2-MG obtained from peanut oil, the final product contained more than 90% caprylic acid in the sn1- and sn3-positions, whereas the sn2-position was composed of 98.5% unsaturated long-chain fatty acids. Reaction conditions for both steps were optimized with respect to source and immobilization of lipase, water activity, and solvent.     

Teaching mathematical modeling software for multiobjective optimization in chemical engineering courses

This paper expects to give undergraduate students some guidelines about how to incorporate environmental considerations in a chemical supply chain and how the introduction of these concerns have an important effect on the results obtained in the multiobjective optimization problem where both economic and environmental aspects are considered simultaneously.To extend the economic and environmental assessment outside the chemical plant and to identify the tradeoffs associated with the reality of chemical and petrochemical industries, a simplified problem of a chemical supply chain is proposed as a case study.The inclusion of environmental concerns to this economic problem make this new case study a good example for undergraduate students interested in implementing simultaneous economic and environmental considerations in the chemical process design incorporating mathematical modeling software for solving this multiobjective problem.Thus, the final objective of this paper is to show to undergraduate students how environmental together with economic considerations could have an important impact in the logistics of a supply chain and how multiobjective optimization could be used to make better decisions in the design of chemical processes including its supply chain.To reach our purpose, the Pareto curve of the supply chain is obtained using the ?-constraint method. In addition, the tradeoffs of this multiobjective optimization have been identified and analyzed and ultimately a good decision based on the set of ‘equivalent’ optimal solutions for this chemical supply chain problem determined.     

对化工企业可持续发展的若干思考

论述了化工企业实施可持续发展的紧迫性,从动力机制、技术进步、治理环境污染等方面研究了化工企业可持续发展的对策。     

化工可持续发展的思考

介绍了社会可持续发展的概念和重要性,及实施生态化工的一些具体途径:化学过程及工艺的绿色化,可再生资源的开发及废弃资源的综合利用,发展纳米科技及微化工技术,强化过程及化工集成,建设生态工业园区,并推进化工信息化。     

化工生态工业园区可持续发展评价研究

化学工业对资源、能源的需求量高,对环境的负效应大,因此有必要建立科学的指标体系和综合评价模型对化学工业园区可持续发展水平进行评价。通过对可持续发展评价现有研究结果的总结,根据化工生态工业园区的基本内涵和特点,建立了包括园区发展现状、发展协调度及发展潜力的生态工业园区可持续发展评价指标体系,涉及经济、环境、生态、技术及意识等方面,并给出了生态工业园可持续发展的综合评价模型。该指标体系及评价方法为客观分析评价化工生态工业园区的可持续发展水平,制定正确的系统管理调控措施和发展策略提供理论依据。