Electrochemical Oxidation of Biomass Derived 5-Hydroxymethylfurfural (HMF): Pathway/Mechanism, Catalysts and Coupling Reactions

2021 ◽  
Author(s):  
Yuechao Yang ◽  
Tiancheng Mu
Keyword(s):  
Electrochemical Oxidation ◽  
Value Added ◽  
Promising Method ◽  
Coupling Reactions ◽  
Electrochemical Conversion ◽  
Operation Conditions ◽  
Wide Range

Electrochemical conversion has been emerging as a powerful and promising method to produce a wide range of high-value-added chemicals on account of mild operation conditions, controllable selectivity, and scalability. 5-hydroxymethylfurfural...

CO2reduction: the quest for electrocatalytic materials

2017 ◽  
Vol 5 (18) ◽  
pp. 8230-8246 ◽  
Author(s):  
Bahareh Khezri ◽  
Adrian C. Fisher ◽  
Martin Pumera
Keyword(s):  
Carbon Dioxide ◽  
Reaction Kinetics ◽  
Value Added ◽  
Kinetics And Thermodynamics ◽  
Electrochemical Conversion ◽  
Wide Range ◽  
Fundamental Understanding

Electrochemical conversion of CO2has attracted attention worldwide since this process can convert carbon dioxide to a wide range of value-added chemicals. This reaction required the development of efficient electrocatalysts and fundamental understanding of the reaction kinetics and thermodynamics to overcome the current challenges.

OPPORTUNITIES FOR STRATEGIC DEVELOPMENT OF BIO-ECONOMY IN THE FOOD AND TOURISM INDUSTRY

2018 ◽  
Vol 28 (5) ◽  
pp. 1681-1684
Author(s):  
Georgi Toskov ◽  
Ana Yaneva ◽  
Stanko Stankov ◽  
Hafize Fidan
Keyword(s):  
National Level ◽  
Value Added ◽  
Tourism Industry ◽  
Small Companies ◽  
Food Sector ◽  
Strategic Development ◽  
Innovation Potential ◽  
Wide Range ◽  
Foreign Brands ◽  
Value Added Products

The European Commission defines the bioeconomy as "the production of renewable biological resources and the conversion of these resources and waste streams into value added products, such as food, feed, bio-based products and bioenergy. Its sectors and industries have strong innovation potential due to their use of a wide range of sciences, enabling and industrial technologies, along with local and implied knowledge." The Bulgarian food industry faces a lot of challenges on the local and national level, which have direct influence on the structure of the production companies. Most of the enterprises from the food sector produce under foreign brands in order to be flexible partners to the large Bulgarian retail chains. The small companies from the food sector are not able to develop as an independent competitive producer on the territory of their local markets. This kind of companies rarely has a working strategy for positioning on new markets. In order to consolidate their already built positions for long period of time, the producers are trying to optimize their operations in a short term. However, the unclear vision of the companies for the business segment does not allow them to fully develop. Tourism in Bulgaria is a significant contributor to the country's economy.

Monodentate Trialkylphosphines: Privileged Ligands in Metal-catalyzed Crosscoupling Reactions

2020 ◽  
Vol 24 (3) ◽  
pp. 231-264 ◽  
Author(s):  
Kevin H. Shaughnessy
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Aryl Bromides ◽  
Wide Range ◽  
Sterically Demanding ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Phosphines are widely used ligands in transition metal-catalyzed reactions. Arylphosphines, such as triphenylphosphine, were among the first phosphines to show broad utility in catalysis. Beginning in the late 1990s, sterically demanding and electronrich trialkylphosphines began to receive attention as supporting ligands. These ligands were found to be particularly effective at promoting oxidative addition in cross-coupling of aryl halides. With electron-rich, sterically demanding ligands, such as tri-tertbutylphosphine, coupling of aryl bromides could be achieved at room temperature. More importantly, the less reactive, but more broadly available, aryl chlorides became accessible substrates. Tri-tert-butylphosphine has become a privileged ligand that has found application in a wide range of late transition-metal catalyzed coupling reactions. This success has led to the use of numerous monodentate trialkylphosphines in cross-coupling reactions. This review will discuss the general properties and features of monodentate trialkylphosphines and their application in cross-coupling reactions of C–X and C–H bonds.

α-Alkoxyalkyl Triphenylphosphonium Salts: Synthesis and Reactions

2019 ◽  
Vol 23 (16) ◽  
pp. 1738-1755
Author(s):  
Humaira Y. Gondal ◽  
Zain M. Cheema ◽  
Abdul R. Raza ◽  
Ahmed Abbaskhan ◽  
M. I. Chaudhary
Keyword(s):  
Carbonyl Compounds ◽  
Claisen Rearrangement ◽  
Alder Reaction ◽  
Coupling Reactions ◽  
Phosphonium Salts ◽  
Organic Transformations ◽  
Enol Ethers ◽  
Wide Range ◽  
Synthetic Methodologies ◽  
Alkoxy Groups

Following numerous applications of Wittig reaction now functionalized phosphonium salts are gaining attention due to their characteristic properties and diverse reactivity. This review is focused on α-alkoxyalkyl triphenylphosphonium salts: an important class of functionalized phosphonium salts. Alkoxymethyltriphenylphosphonium salts are majorly employed in the carbon homologation of carbonyl compounds and preparation of enol ethers. Their methylene insertion strategy is extensively demonstrated in the total synthesis of a wide range of natural products and other important organic molecules. Similarly enol ethers prepared thereof are important precursors for different organic transformations like Diels-Alder reaction, Claisen rearrangement, Coupling reactions, Olefin metathesis and Nazarov cyclization. Reactivity of these α-alkoxyalkylphosphonium salts have also been studied in the nucleophilic substitution reactions. A distinctive application of this class of phosphonium salts was recently reported in the phenylation of carbonyl compounds under very mild conditions. Synthesis of structurally diverse alkoxymethyltriphenylphosphonium salts with variation in alkoxy groups as well as counter anions are reported in literature. Here we present a detailed account of different synthetic methodologies for the preparation of this unique class of quaternary phosphonium salts and their applications in organic synthesis.

scholarly journals Effects of a Twin-Screw Extruder Equipped with a Molten Resin Reservoir on the Mechanical Properties and Microstructure of Recycled Waste Plastic Polyethylene Pellet Moldings

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1058
Author(s):  
Hikaru Okubo ◽  
Haruka Kaneyasu ◽  
Tetsuya Kimura ◽  
Patchiya Phanthong ◽  
Shigeru Yao
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Value Added ◽  
Industrial Applications ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Polymer Properties ◽  
Wide Range ◽  
Twin Screw ◽  
Recycled Plastics

Each year, increasing amounts of plastic waste are generated, causing environmental pollution and resource loss. Recycling is a solution, but recycled plastics often have inferior mechanical properties to virgin plastics. However, studies have shown that holding polymers in the melt state before extrusion can restore the mechanical properties; thus, we propose a twin-screw extruder with a molten resin reservoir (MSR), a cavity between the screw zone and twin-screw extruder discharge, which retains molten polymer after mixing in the twin-screw zone, thus influencing the polymer properties. Re-extruded recycled polyethylene (RPE) pellets were produced, and the tensile properties and microstructure of virgin polyethylene (PE), unextruded RPE, and re-extruded RPE moldings prepared with and without the MSR were evaluated. Crucially, the elongation at break of the MSR-extruded RPE molding was seven times higher than that of the original RPE molding, and the Young’s modulus of the MSR-extruded RPE molding was comparable to that of the virgin PE molding. Both the MSR-extruded RPE and virgin PE moldings contained similar striped lamellae. Thus, MSR re-extrusion improved the mechanical performance of recycled polymers by optimizing the microstructure. The use of MSRs will facilitate the reuse of waste plastics as value-added materials having a wide range of industrial applications.

scholarly journals Study on Friction in Automotive Shock Absorbers Part 1: Friction Simulation Using a Dynamic Friction Model in the Contact Zone of an FEM Model

Vehicles ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 212-232
Author(s):  
Ludwig Herzog ◽  
Klaus Augsburg
Keyword(s):  
Ride Comfort ◽  
Viscous Friction ◽  
Simulation Method ◽  
Friction Model ◽  
Model Parameters ◽  
Dynamic Friction ◽  
Friction Modeling ◽  
Shock Absorbers ◽  
Operation Conditions ◽  
Wide Range

The important change in the transition from partial to high automation is that a vehicle can drive autonomously, without active human involvement. This fact increases the current requirements regarding ride comfort and dictates new challenges for automotive shock absorbers. There exist two common types of automotive shock absorber with two friction types: The intended viscous friction dissipates the chassis vibrations, while the unwanted solid body friction is generated by the rubbing of the damper’s seals and guides during actuation. The latter so-called static friction impairs ride comfort and demands appropriate friction modeling for the control of adaptive or active suspension systems. In this article, a simulation approach is introduced to model damper friction based on the most friction-relevant parameters. Since damper friction is highly dependent on geometry, which can vary widely, three-dimensional (3D) structural FEM is used to determine the deformations of the damper parts resulting from mounting and varying operation conditions. In the respective contact zones, a dynamic friction model is applied and parameterized based on the single friction point measurements. Subsequent to the parameterization of the overall friction model with geometry data, operation conditions, material properties and friction model parameters, single friction point simulations are performed, analyzed and validated against single friction point measurements. It is shown that this simulation method allows for friction prediction with high accuracy. Consequently, its application enables a wide range of parameters relevant to damper friction to be investigated with significantly increased development efficiency.

Analysis and Reduction of the Waste in the Work Process Using Time Study Analysis: A Case Study

2014 ◽  
Vol 660 ◽  
pp. 971-975 ◽  
Author(s):  
Mohd Norzaim bin Che Ani ◽  
Siti Aisyah Binti Abdul Hamid
Keyword(s):  
Cycle Time ◽  
Lean Manufacturing ◽  
Value Added ◽  
Time Study ◽  
Study Approach ◽  
Root Cause ◽  
Wide Range ◽  
Unit Of Work ◽  
Time Required ◽  
The Impact

Time study is the process of observation which concerned with the determination of the amount of time required to perform a unit of work involves of internal, external and machine time elements. Originally, time study was first starting to be used in Europe since 1760s in manufacturing fields. It is the flexible technique in lean manufacturing and suitable for a wide range of situations. Time study approach that enable of reducing or minimizing ‘non-value added activities’ in the process cycle time which contribute to bottleneck time. The impact on improving process cycle time for organization that it was increasing the productivity and reduce cost. This project paper focusing on time study at selected processes with bottleneck time and identify the possible root cause which was contribute to high time required to perform a unit of work.

scholarly journals Holistic Approach to Design, Test, and Optimize Stand-Alone SOFC-Reformer Systems

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 348
Author(s):  
Michael Höber ◽  
Benjamin Königshofer ◽  
Philipp Wachter ◽  
Gjorgji Nusev ◽  
Pavle Boskoski ◽  
...  
Keyword(s):  
Rural Communities ◽  
High Efficiency ◽  
Diffusion Processes ◽  
Holistic Approach ◽  
Maximum Error ◽  
Gas Diffusion ◽  
Electrochemical Analysis ◽  
Internal Reforming ◽  
Operation Conditions ◽  
Wide Range

Reliable electrical and thermal energy supplies are basic requirements for modern societies and their food supply. Stand-alone stationary power generators based on solid oxide fuel cells (SOFC) represent an attractive solution to the problems of providing the energy required in both rural communities and in rurally-based industries such as those of the agricultural industry. The great advantages of SOFC-based systems are high efficiency and high fuel flexibility. A wide range of commercially available fuels can be used with no or low-effort pre-treatment. In this study, a design process for stand-alone system consisting of a reformer unit and an SOFC-based power generator is presented and tested. An adequate agreement between the measured and simulated values for the gas compositions after a reformer unit is observed with a maximum error of 3 vol% (volume percent). Theoretical degradation free operation conditions determined by employing equilibrium calculations are identified to be steam to carbon ratio (H2O/C) higher 0.6 for auto-thermal reformation and H2O/C higher 1 for internal reforming. The produced gas mixtures are used to fuel large planar electrolyte supported cells (ESC). Current densities up to 500 mA/cm2 at 0.75 V are reached under internal reforming conditions without degradation of the cells anode during the more than 500 h long-term test run. More detailed electrochemical analysis of SOFCs fed with different fuel mixtures showed that major losses are caused by gas diffusion processes.

Valuing Streamflow Forecasts in Centrally Controlled Power Systems

2021 ◽  
Author(s):  
Jordan Kern ◽  
Nathalie Voisin ◽  
Sean Turner ◽  
Hongxiang Yan ◽  
Konstantinos Oikonomou
Keyword(s):  
Power Systems ◽  
Electricity Markets ◽  
Management Strategies ◽  
Profit Maximization ◽  
Value Added ◽  
Marginal Value ◽  
Wide Range ◽  
Streamflow Forecasts ◽  
Hydropower Production ◽  
Bulk Power

<p>Given the wide range of institutional and market contexts in which hydroelectric dams are operated, determining the value added from improvements in hydrologic forecasts is a challenge. Many previous examples of hydrologic forecasts being used to optimize hydropower production strategies at dams focus on a single reservoir system or watershed, with a key assumption that the marginal value of hydropower production is exogenously-defined (dams are ‘price takers’ in markets for electricity that exhibit no market power). In some cases, this may accurately reflect current institutional boundaries and decision making processes. However, with increased attention being paid to how more coordinated grid management strategies, including management of hydropower assets, could facilitate deep integration of renewable energy, it is critical to understand how the use of improved hydrologic forecasts could produce wider grid-scale benefits, including  lower costs and emissions. In this study, we quantify the value of streamflow forecasts to a centralized power system operator in charge of coordinating sub-weekly operations of hydropower assets, using the Western U.S. as a case study. We propagate flow forecasts through realistic models of reservoir operations and models of bulk power systems/wholesale electricity markets. Our results shed light on how the value of flow forecasts to grid operations can vary across regions and power systems. They also highlight the potential for conflicts between firm-specific objectives (profit maximization) and system-wide objectives (minimization of costs and emissions) when determining value added from hydrologic forecasts.  </p>

scholarly journals Development of a condition monitoring system for the refractory lining of induction crucible steelmaking furnaces

Vestnik IGEU ◽  
2019 ◽  
pp. 58-66
Author(s):  
I.Yu. Dolgikh ◽  
M.G. Markov
Keyword(s):  
Monitoring System ◽  
Refractory Lining ◽  
Control Object ◽  
Practical Implementation ◽  
Microprocessor System ◽  
Induction Melting ◽  
Monitoring And Control ◽  
Operation Conditions ◽  
Emergency Shutdown ◽  
Wide Range

A wide range of technological advantages of induction crucible melting furnaces makes their use in various sectors of metallurgical production relevant. However, hard operation conditions of the refractory lining of such furnaces makes it necessary to constantly monitor its condition, with the aim to extend the crucible life and prevent emergencies. Moreover, traditional methods based on the use of a bottom electrode and indication of current leakage to earth do not provide a continuous display of the lining destruction degree and make it possible to register only a critical level that requires an emergency shutdown and emptying of the furnace. This circumstance makes it necessary to develop and implement specialized electrical systems with a monitoring and control system that ensures the determination and visualization of the lining wear level and, if necessary, makes an emergency shutdown of the equipment from the power source. The developed complex is based on a microprocessor system that continuously measures the temperature at the control points at the boundary between the bottom and crucible base layers and compares the obtained values with the settings, which are determined previously on a two-dimensional axisymmetric model of the designed furnace by solving the stationary heat conduction equation at various levels of lining failure. We have developed the structure, scheme, and program for a microprocessor-based monitoring and emergency shutdown system of an induction furnace, as well as a mathematical model of the control object, which allows determining the temperature settings. The reliability of the results is confirmed by the applicability of the models to real objects, and is verified by debugging the microprocessor part in the MPLab-Sim and Proteus programs. The obtained results can be used in the practical implementation of the monitoring system and emergency shutdown of induction melting furnaces, which allows increasing the safety of their operation and extending the lining life due to timely repair.

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