Development Of Chemical Processes Research Articles

Simulation Study of Citronellol-geraniol Rectification Tower Based on Aspen Plus Software

Aspen Plus is a large-scale chemical simulation software based on steady-state chemical simulation, optimization, sensitivity analysis and economic evaluation. It can analyze the planning, research, development and technical reliability of chemical processes. High-purity citronellol and geraniol, the main high-value components of citronella oil, make the rectification and purification process difficult due to their boiling point and heat sensitivity, with high separation cost and poor effect, resulting in low economic benefits. This paper uses Aspen Plus software to estimate the physical properties of citronellol and geraniol system through known structural formula and room temperature boiling point; uses citronellol-geraniol vapor-liquid equilibrium experimental data to select physical properties analytical methods of Aspen Plus software; conducts process design and simulation of the high vacuum separation of citronellol and geraniol by using DSTWU simple simulation tower and RadFrac strict simulation tower respectively, gets the process parameters of citronellol and geraniol distillation tower, checks the separation process, and optimizes the separation conditions, which provide support for using industrial production in the high-purity separation of citronella oil system.

Uniting laboratory automation, DoE data, and modeling techniques to accelerate chemical process development

Rapid knowledge building of chemical processes with highly automated DoE (HAD) and statistical analyses and modeling.

Sustainable approaches for steroid synthesis

Steroids are important scaffolds for the synthesis of molecules of pharmaceutical interest and constitute a distinct family of natural products. The demand for green and sustainable chemistry has fostered for the development of new reactions and chemical processes in steroidal chemistry. This review describes state-of-the-art approaches such as heterogeneous catalysis, microwave synthesis and microbial transformations for steroid synthesis.

Three-Component One-Pot Approach to Highly Efficient and Sustainable Synthesis of the Functionalized Quinolones via Linear/Branched Domino Protocols, Key Synthetic Methods for the Floxacin of Quinolone Drugs.

The development of a clear chemical process to produce diverse value-added chemicals from low-cost raw materials is a particularly attractive concept and represents a considerable challenge in sustainable organic synthesis. Herein, two highly efficient and clear methods for the synthesis of quinolone derivatives based on a linear/branched domino protocol under sustainable conditions were established. The main advantages of these protocols are the simple experimental procedure, high bond-forming efficiency, inexpensive readily available starting materials, moderate to excellent yields with good functional group compatibility, and nonchromatographic purification, which render these methods particularly attractive for the sustainable preparation of biologically and medicinally interesting molecules. To demonstrate the practical utility of our protocol, existing pharmaceutical sarafloxacin was successfully synthesized. Furthermore, a postulated reaction pathway including condensation reaction/nucleophilic aromatic substitution/Friedel–Crafts reaction for these domino reactions is also discussed.

Scalable Process for the Production of a Highly Energetic Bromoacetylene Building Block

3-(Bromoethynyl)azetidine is a highly energetic building block (decomposition energy up to −1800 J g–1) that was required in multikilogram quantities for the production of an API. The development of a four-step, fully telescoped, scalable sequence for its synthesis is described, along with a detailed safety study of the corresponding hydrochloride salt in order to determine the potential explosive properties and transport classification. A screen of counterions identified the (+)-camphorsulfonic acid salt as the most suitable form for mitigation of the energetic properties, as judged by differential scanning calorimetry (onset 182 °C, energy −876 J g–1). This case study demonstrates how a daunting chemical structure can be “tamed” by chemical process development, tuning of molecular properties, and thorough safety investigations.

Machine learning meets continuous flow chemistry: Automated optimization towards the Pareto front of multiple objectives

Automated development of chemical processes requires access to sophisticated algorithms for multi-objective optimization, since single-objective optimization fails to identify the trade-offs between conflicting performance criteria. Herein we report the implementation of a new multi-objective machine learning optimization algorithm for self-optimization, and demonstrate it in two exemplar chemical reactions performed in continuous flow. The algorithm successfully identified a set of optimal conditions corresponding to the trade-off curve (Pareto front) between environmental and economic objectives in both cases. Thus, it reveals the complete underlying trade-off and is not limited to one compromise as is the case in many other studies. The machine learning algorithm proved to be extremely data efficient, identifying the optimal conditions for the objectives in a lower number of experiments compared to single-objective optimizations. The complete underlying trade-off between multiple objectives is identified without arbitrary weighting factors, but via true multi-objective optimization.

Guidelines for Process Safety Hazard Assessment Based on Process Information

In any new chemical process development and design, process safety is a critical aspect to be considered besides economic and technical feasibility of the manufacture of the product. A lack of proper hazard assessment during the design phase may later result in accidents with disastrous consequences to workers, the public as well as the environment. Many methods have been introduced to qualitatively and quantitatively assess the safety level of processes. Despite the availability of a large amount of methods, a systematic framework that details guidelines for hazard identification, risk assessment, safety measure design, and safe critical decision-making is still missing. To address this issue, the main objective of this study was to propose a systematic framework that outlines comprehensive guidelines for assessing the safety performance of processes based on information from the piping and instrumentation diagram (P&ID). Apart from proposing the framework, appropriate strategies for minimizing safety hazards and risks are also recommended. In addition, the user is assisted in selecting the most appropriate assessment method according to his or her needs and the scope and constraints of the assessment. A case study is presented to illustrate the application of the proposed framework.

Aerobic Electrochemical Oxygenation of Light Hydrocarbons Catalyzed by an Iron–Tungsten Oxide Molecular Capsule

The selective oxidation of light hydrocarbons and their valorization with only dioxygen (O2) are important transformations toward development of efficient chemical processes. Monooxygenase enzymes can catalyze selective aerobic reactions under reducing and protic conditions. The translation of such enzymatic pathways to the practical electrocatalytic oxidation of light, gaseous hydrocarbons, using O2 as sole oxidant is now reported. An iron–tungsten oxide inorganic molecular catalyst with a capsular structure {Fe30W72} stabilized inside by sulfate/bisulfate anions provides a protic environment where three iron atoms are located at each of the pores of the capsule leading to a unique and potent active site for the oxidation reactions. Under mild electrochemical conditions, 1.8 V, in water at room temperature, using O2 from air, we demonstrate the low-pressure (1–2 bar) hydroxylation of alkanes, notably ethane to acetic acid, and the ozone like cleavage of the carbon–carbon double bonds of alkenes. Typical ...

Resveratrol, phenolic antioxidants, and saccharides in South American red wines

Resveratrol, phenolic antioxidants, and saccharides in South American red wines Daniel E Osorio-Macías,1,2 Pamela Vásquez,3 Cristhian Carrasco,3 Bjorn Bergenstahl,1 J Mauricio Peñarrieta2 1Department of Food Technology, Faculty of Engineering LTH, Lund University, Lund, Sweden; 2School of Chemistry, Faculty of Pure and Natural Sciences, 3Institute of Research and Development of Chemical Processes, Department of Chemical Engineering, Faculty of Engineering, Universidad Mayor de San Andrés (UMSA), La Paz, Bolivia Abstract: Wine is an important beverage with a long tradition, and its moderate consumption may be considered beneficial for human health. Although there are many studies regarding phenolic compounds in wines, there is a lack of information about antioxidants and phenolic content in South American wines. In this study, 35 South American red wines from four different countries, vintages 2004–2013, purchased at retail stores in La Paz, Bolivia, were studied. Resveratrol content, total antioxidant capacity (TAC) by the 2,2′-azino-bis(3-ethylbenzotiazoline-6-sulfonic acid) (ABTS) and ferric-reducing antioxidant power (FRAP) methods, total phenolic content (TPH), total flavonoids (TF), and main saccharides were assessed using the well-established spectrophotometric and high-performance liquid chromatography methods. The results ranged from 4 to 24 mmol/L for TAC determined by ABTS method and 14 to 43 mmol/L for TAC determined by FRAP method, 1600 to 3500 mg gallic acid equivalents/L for TPH, and 2 to 6 mmol catechin equivalents /L for TF. The resveratrol content ranged from 0.1 to 8 mg/L. Saccharides, glucose, and fructose content ranged from 0.4 to 10 g/L, 1.4 to 8.6 g/L, and 0.2 to 12 g/L, respectively. There was a high correlation among the different methods. The results showed that some wines growing at high altitude (>1500 meters above the sea level) have higher amounts of TAC and phenolic content, including resveratrol, while non-varietal wines showed the lowest values. It was also observed that the saccharose content in some wines was surprisingly high, suggesting saccharose dosing after fermentation. Keywords: ABTS, FRAP, high altitude, HPLC, PCA, Bolivia

Vanillin derived from lignin liquefaction: a sustainability evaluation

Hydrothermal liquefaction of lignin has been demonstrated as a successful process for the synthesis of value-added phenolic chemical compounds such as vanillin. Vanillin has commercial value as a flavor and fragrance ingredient. This study performs a comparative process simulation and life cycle assessment (LCA) of synthesis of vanillin from depolymerization of lignin, one of the most abundant natural polymers on Earth. Laboratory-scale scenarios for alkali lignin treatment were analyzed using LCA (TRACI 2.1) and green design metrics (process and energy efficiency, waste prevention, renewability, and hazard/pollution avoidance); scenarios included temperature, residence time, lignin loading, gas presence, and catalyst variants. Results show that models which adhere better to green design metrics also result in environmental impact reductions, demonstrating a positive correlation between both sustainability metrics. Vanillin yield increased ~ 7% when reaction time increased from 10 to 20 min; however, the energy used for maintaining operational conditions during process increased between 10 and 50%. Catalyst selection was found to be a deterministic factor affecting results. A catalytic system comprised of a heterogeneous catalyst (nickel oxide) and acidic homogeneous catalyst (supercritical carbon dioxide) was identified as the best option; the catalyst reduced carcinogenic and ecotoxicity impacts by ~ 80 and 90%, respectively when compared to molybdenum oxide. Use of energy and dichloromethane were found to be significant overall environmental impact contributors. Laboratory results can be used and evaluated via LCA to identify sustainable pathways for commercial chemical processing development.

Development of Chemical Decontamination Process Based on Ozone for System Surfaces with Chromium Containing Oxides

Chromite or chromium containing oxides are formed as a protective oxide film on the stainless steel surface of heat transport systems. The chemical dissolution of these passive oxide films forms an important step in decontamination formulation development for water-cooled nuclear reactor systems. Dissolved ozone as a reagent was tested for effective chemical dissolution of Fe3+ substituted in nickel chromite and individual component oxides. The study showed the importance of the solution pH and temperature on the dissolution kinetics of Cr2O3, NiO, and NiFexCr2-xO4. Neutral water pH or 0.04 mM OH− were better for achieving a high dissolution rate for chromium containing oxides compared to acidic (2.5 mM H+) or alkaline conditions. In an acidic condition, the release of nickel from NiO or nickel chromite was more in the ozone medium compared to a high pH condition. Substitution of Fe3+ in nickel chromite affected the dissolution behavior in the ozone medium. The dissolution of Fe3+ substituted in nickel chromite showed a small increase in the dissolution rate constant with up to composition x = 0.4, and further increase in the Fe3+ composition in the oxide lattice decreased the dissolution rate constant.

Dissolution of nickel and chromium from Ni-Cr-Fe-O oxide by oxidative treatment with permanganate

Ni-Cr-Fe mixed oxides (NiCrxFe2-xO4) are formed as a corrosion oxide films on structural material surface of coolant or heat transport circuit in water-cooled nuclear reactors. Study on the dissolution behavior of these oxides forms a critical part in development of an efficient chemical decontamination process for the nuclear industry. The present study describes release of Ni and Cr in permanganate medium from the chromium substituted nickel ferrite and also on the mechanistic aspects of oxide dissolution. These oxides were synthesized by combustion method and characterized by the XRD, XPS and Raman spectroscopy. The dissolution kinetics of oxide in permanganate medium was modeled by Shrinking Sphere Model and General Kinetic law Equation. The rate constant for oxide dissolution increased with the Cr substitution in nickel ferrite. Presence of chromium in the oxide lattice affect the release of nickel and also a minimum chromium concentration in the lattice is required for the release of nickel from the oxide lattice during the permanganate treatment. However, when the chromium substitution (x) is increased to 0.6 and above, the nickel release was lowered.

Liquid–liquid centrifugal separation — New equipment for optical (photographic) evaluation at laboratory scale

Since liquid–liquid separation techniques are applied in chemical process industry, research and development received a strong level of attention. Thus, liquid–liquid separation behavior in gravity equipment – e.g., in settling tanks – especially sedimentation and coalescence are investigated in detail. However, for liquid–liquid separation in centrifugal equipment – e.g., tube centrifuges – only superficial knowledge and less detailed investigations are given in open literature. This work focuses on the development of a new laboratory equipment for optical (photographic) evaluation of the centrifugal liquid–liquid separation processes. A new stirred centrifugal batch settling cell (SCBSC) utilizing a rotor–rotor/stator concept, experimental setup and method as well as analytical procedures are presented and discussed. Furthermore, results of mixing and separation process within the SCBSC are shown. The centrifugal force field thereby affects the required differential rotation speed for the dispersion process. The evaluation of the separation process is presented and discussed considering sedimentation and coalescence curves exemplary for two liquid–liquid systems. In the course of this, a comparison between gravitational and centrifugal separation was successful. Finally, the separation behavior is described by a dimensionless dispersion number.

Optimization-Based Approach To Process Synthesis for Process Intensification: General Approach and Application to Ethanol Dehydration

Process synthesis and intensification are well-known and powerful tools for the development of chemical processes with improved energy and cost efficiency. However, even though a combination of both provides the most potential for exploiting these improvements, process synthesis still focuses on classical unit operations, while intensified process options are rather delayed and considered mainly for retrofitting. This not only limits the result of process synthesis but also impedes the application of intensified process options, as they need to justify additional investment for process modification. In order to reveal improved process options and reduce the barrier for intensified processes, the current article presents a process synthesis approach which generates thermodynamically feasible phenomena-based flowsheets by means of superstructure optimization. The approach provides maximum flexibility for integrating and modifying the involved phenomena building blocks, which only afterward are interpreted a...

Assessment of Sustainability Indicators for Biodiesel Production

Biodiesel production may provide a sustainable route to reduce environmental pollution caused by fossil fuel consumption. In order to minimize environmental impacts of biodiesel production, the chemical process should be optimized to minimize waste generation and energy consumption. Therefore, it is important to design biodiesel chemical reactions and processes using green chemistry and green engineering principles to develop sustainable chemical processes. This study provides the results of the synergistic effect of microwave and ultrasound irradiations to produce biodiesel using ethanol or methanol as the alcohol donor. The biodiesel yields are presented along with their respective green metrics, such as atom economy, environmental factor (E-factor), atom economy (utilization) or atomic efficiency, mass intensity, reaction mass efficiency, atom utilization, and stoichiometric factor. These green metrics are crucial to determine the sustainability and environmental impact of biodiesel production. Evaluation of these green metrics indicates that methanol is a better alternative for biodiesel production provided it is derived from renewable sources. Sustainability indicator concepts used for biodiesel production in this study can be applied to various biofuels and other chemical reaction designs, synthesis and process development.

Catalyst‐Free, Glycerol‐Assisted Facile Approach to Imidazole‐Fused Nitrogen‐Bridgehead Heterocycles

AbstractA completely regioselective, environmentally benign strategy for the facile synthesis of biologically important imidazole‐fused nitrogen‐bridgehead heterocycles has been developed using glycerol/water 4:1 as a green promoting media. The methodology involves the simple coupling of 2‐halocarbonyl compounds with 2‐aminopyridines, 2‐aminopyrimidines, 2‐aminopyrazines to obtain a variety of 2‐aryl substituted imidazo‐pyridines, imidazo‐pyrimidines and imidazo‐pyrazines containing bridgehead nitrogen. This protocol eliminates the use of toxic catalysts and volatile organic solvents ‐ two key principles in the development of a green chemical process. Other significant highlights include mild reaction conditions, operational simplicity, short reaction times, easy workup and purification process, high yields and potential for scale‐up.

Supported Dendrimer-Encapsulated Metal Clusters: Toward Heterogenizing Homogeneous Catalysts.

Recyclable catalysts, especially those that display selective reactivity, are vital for the development of sustainable chemical processes. Among available catalyst platforms, heterogeneous catalysts are particularly well-disposed toward separation from the reaction mixture via filtration methods, which renders them readily recyclable. Furthermore, heterogeneous catalysts offer numerous handles-some without homogeneous analogues-for performance and selectivity optimization. These handles include nanoparticle size, pore profile of porous supports, surface ligands and interface with oxide supports, and flow rate through a solid catalyst bed. Despite these available handles, however, conventional heterogeneous catalysts are themselves often structurally heterogeneous compared to homogeneous catalysts, which complicates efforts to optimize and expand the scope of their reactivity and selectivity. Ongoing efforts in our laboratories are aimed to address the above challenge by heterogenizing homogeneous catalysts, which can be defined as the modification of homogeneous catalysts to render them in a separable (solid) phase from the starting materials and products. Specifically, we grow the small nanoclusters in dendrimers, a class of uniform polymers with the connectivity of fractal trees and generally radial symmetry. Thanks to their dense multivalency, shape persistence, and structural uniformity, dendrimers have proven to be versatile scaffolds for the synthesis and stabilization of small nanoclusters. Then these dendrimer-encapsulated metal clusters (DEMCs) are adsorbed onto mesoporous silica. Through this method, we have achieved selective transformations that had been challenging to accomplish in a heterogeneous setting, e.g., π-bond activation and aldol reactions. Extensive investigation into the catalytic systems under reaction conditions allowed us to correlate the structural features (e.g., oxidation states) of the catalysts and their activity. Moreover, we have demonstrated that supported DEMCs are also excellent catalysts for typical heterogeneous reactions, including hydrogenation and alkane isomerization. Critically, these investigations also confirmed that the supported DEMCs are heterogeneous and stable against leaching. Catalysts optimization is achieved through the modulation of various parameters. The clusters are oxidized (e.g., with PhICl2) or reduced (e.g., with H2) in situ. Changing the dendrimer properties (e.g., generation, terminal functional groups) is analogous to ligand modification in homogeneous catalysts, which affect both catalytic activity and selectivity. Similarly, pore size of the support is another factor in determining product distribution. In a flow reactor, the flow rate is adjusted to control the residence time of the starting material and intermediates, and thus the final product selectivity. Our approach to heterogeneous catalysis affords various advantages: (1) the catalyst system can tap into the reactivity typical to homogeneous catalysts, which conventional heterogeneous catalysts could not achieve; (2) unlike most homogeneous catalysts with comparable performance, the heterogenized homogeneous catalysts can be recycled; (3) improved activity or selectivity compared to conventional homogeneous catalysts is possible because of uniquely heterogeneous parameters for optimization. In this Account, we will briefly introduce metal clusters and describe the synthesis and characterizations of supported DEMCs. We will present the catalysis studies of supported DEMCs in both the batch and flow modes. Lastly, we will summarize the current state of heterogenizing homogeneous catalysis and provide future directions for this area of research.

Molecular dynamics simulation of self-diffusion coefficients for several alkanols

The transfer properties and microscopic structures of methanol, ethanol, 1-propanol, 2-propanol, and 1-pentanol in the temperature range from 290 to 450 K and pressure range from 0.1 to 200 MPa were studied by molecular dynamics (MD) simulation through the calculation of the self-diffusion coefficients, velocity autocorrelation functions (VACF), and radial distribution function (RDF). The calculated self-diffusion coefficients conform to the experimental values on the whole, and the temperature has greater influence, which weaken with the increase of the carbon chain, on self-diffusion coefficient than pressure. The factors affecting self-diffusion coefficients were also analyzed from micro perspective by calculation of VACF and RDF, which is helpful to understand the relationship between microscopic structures of fluid and its transfer properties. This work not only provides a reliable simulation method for transfer properties of alkanols, but also provides the prediction data for design and development of chemical processes.

In Situ Electron Microscopy of Plasmon-Mediated Nanocrystal Synthesis.

Chemical processes driven by nonthermal energy (e.g., visible light) are attractive for future approaches to energy conversion, synthesis, photocatalysis, and so forth. The growth of anisotropic metal nanostructures mediated by excitation of a localized surface plasmon resonance (LSPR) is a prototype example of such a reaction. Important aspects, notably the growth mechanism and a possible role of plasmonic "hot spots" within the metal nanostructures, remain poorly understood. Here, we use in situ electron microscopy to stimulate and image the plasmon-mediated growth of triangular Ag nanoprisms in solution. The quantification of the time-dependent evolution of the lateral size and thickness of the nanoprisms, enabled by nanometer-scale real-time microscopy in solution, shows a transition from an early stage of uniform Ag0 incorporation exclusively in the prism side facets to a size regime with accelerated growth in thickness. Differences in attachment rate at this advanced stage correlate with local plasmonic field enhancements, which allows determining the range over which charge carriers transferred from plasmonic hot spots can drive chemistry. Such data support the development of nonthermal chemical processes that depend on plasmonic light harvesting and the transfer of nonequilibrium charge carriers.

High-Throughput Automation in Chemical Process Development.

High-throughput (HT) techniques built upon laboratory automation technology and coupled to statistical experimental design and parallel experimentation have enabled the acceleration of chemical process development across multiple industries. HT technologies are often applied to interrogate wide, often multidimensional experimental spaces to inform the design and optimization of any number of unit operations that chemical engineers use in process development. In this review, we outline the evolution of HT technology and provide a comprehensive overview of how HT automation is used throughout different industries, with a particular focus on chemical and pharmaceutical process development. In addition, we highlight the common strategies of how HT automation is incorporated into routine development activities to maximize its impact in various academic and industrial settings.