scholarly journals Continuous flow hydrogenation of methyl and ethyl levulinate: an alternative route to γ -valerolactone production

2019 ◽  
Vol 6 (5) ◽  
pp. 182233 ◽  
Author(s):  
József M. Tukacs ◽  
Áron Sylvester ◽  
Ildikó Kmecz ◽  
Richard V. Jones ◽  
Mihály Óvári ◽  
...  
Keyword(s):  
Reaction Rate ◽  
Point Of View ◽  
Total System ◽  
Continuous Transformation ◽  
Ethyl Levulinate ◽  
Methyl Levulinate ◽  
System Pressure ◽  
Conversion Rates ◽  
Triphenylphosphine Ligand ◽  
Continuous Hydrogenation

Heterogeneous continuous transformation of methyl levulinate (ML) and ethyl levulinate (EL) to γ -valerolactone (GVL), as a promising C 5 -platform molecule was studied at 100°C. It was proved that the H-Cube ® continuous hydrogenation system equipped with 5% Ru/C CatCart ® is suitable for the reduction of both levulinate esters. While excellent conversion rates (greater than 99.9%) of ML and EL could be achieved in water and corresponding alcohols, the selectivities of GVL were primarily affected by the solvent used. In water, 100% conversion and ca 50% selectivity that represent ca 0.45 mol GVL g metal −1 h −1 productivity towards GVL, were obtained under 100 bar of total system pressure. The application of alcohols as a solvent, which maintained high conversion rates up to 1 ml min –1 flow rate, resulted in lower productivities (less than 0.2 mol GVL g metal −1 h −1 ) of GVL. Therefore, from a synthesis point of view, the corresponding 4-hydroxyvalerate esters could be obtained even at a higher reaction rate. The addition of sulfonated triphenylphosphine ligand (TPPTS) allowed reduction of the system pressure and resulted in the higher selectivity towards GVL.

Synthesis and Evaluation of Levulinic Ester as Biodiesel Additives

2020 ◽  
Vol 71 (8) ◽  
pp. 21-26
Author(s):  
Elena-Emilia Oprescu ◽  
Cristina-Emanuela Enascuta ◽  
Elena Radu ◽  
Vasile Lavric
Keyword(s):  
Maximum Yield ◽  
Strength Distribution ◽  
Point Of View ◽  
Reaction Parameters ◽  
X Ray ◽  
Ethyl Levulinate ◽  
Ft Ir ◽  
Ir Analysis ◽  
Biodiesel Blend ◽  
Acid Strength Distribution

In this study, the SO42-/TiO2-La2O3-Fe2O3 catalyst was prepared and tested in the conversion of fructose to ethyl levulinate . The catalyst was characterized from the point of view of the textural analysis, FT-IR analysis, acid strength distribution, X-ray powder diffraction and pyridine adsorption IR spectra. The influence of the reaction parameters on the ethyl levulinate yield was study. The maximum yield of 37.95% in levulinate esters was obtained at 180 �C, 2 g catalyst and 4 h reaction time. The effect of ethyl levulinate addition to diesel-biodiesel blend in different rates, i.e, 0.5, 1, 2.5, 5 (w.t %) on density, kinematic viscosity and flash point was evaluated and compared with the European specification.

scholarly journals An inland-depots-for-empty-containers-model for the hinterland

2017 ◽  
Vol 2 (2) ◽  
pp. 126-141 ◽  
Author(s):  
Stephanie Finke ◽  
Herbert Kotzab
Keyword(s):  
Linear Optimization ◽  
Point Of View ◽  
Mixed Integer ◽  
Total System ◽  
Empty Container ◽  
Content Type ◽  
Shipping Company ◽  
Linear Optimization Model ◽  
Mixed Integer Linear Optimization ◽  
Empty Containers

Purpose The purpose of this paper is to figure out in which way a hinterland-based inland depot model can help a shipping company in solving the empty container problem at a regional level. The repositioning of empty containers is a very expensive operation that does not generate profits. Consequently, it is very important to provide an efficient empty container management. Design/methodology/approach In this paper, the empty container problem is discussed at a regional repositioning level. For solving this problem, a mixed-integer linear optimization model is developed and validated by using the German hinterland as a case. Findings The findings show that the hinterland-based solution is able to reduce the total system costs by 40 per cent. In addition, total of truck kilometres could be reduced by more than 30 per cent too. Research limitations/implications This research is based on German data only. Originality/value This paper closes the gap in empty container repositioning research by looking at the hinterland dimension from a single shipping company point of view.

A comparative study on direct production of ethyl levulinate from glucose in ethanol media catalysed by different acid catalysts

2013 ◽  
Vol 67 (11) ◽  
Author(s):  
Gui-Zhuan Xu ◽  
Chun Chang ◽  
Wei-Na Zhu ◽  
Bo Li ◽  
Xiao-Jian Ma ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Reaction Rate ◽  
Formation Rate ◽  
Acid Catalyst ◽  
Water Addition ◽  
Initial Glucose Concentration ◽  
Direct Production ◽  
Ethyl Levulinate ◽  
Higher Temperature ◽  
By Products

AbstractDirect production of ethyl levulinate (EL) from glucose catalysed by a liquid acid catalyst (sulfuric acid) and a solid acid zeolite catalyst USY NKF-7 (USY) in ethanol media was investigated in this study. Effects of the initial glucose concentration (C G0), reaction temperature (T), amount of acid catalyst, and water addition on the yields of EL were compared, respectively. The results show that higher yield of EL can be obtained at lower C G0. Higher temperature and acid concentration can accelerate the reaction rate, but the formation rate of the by-products increases more quickly than that of EL. Water addition also can result in the decrease of the yield of EL. Although sulfuric acid is efficient in the production of EL, the USY is more efficient in converting glucose to 5-ethoxymethyl-2-furaldehyde. Moreover, the use of USY can limit the diethyl ether production, and it can be reused for multiple times.

The Effect of Scalling-Up and Hydrodynamic Properties of Stirring System on the Kinetics of Vegetable Oil Hydrogenation

1993 ◽  
Vol 58 (2) ◽  
pp. 320-327
Author(s):  
Ivan Dědek
Keyword(s):  
Reaction Kinetics ◽  
Reaction Rate ◽  
Specific Effect ◽  
Scaling Up ◽  
Point Of View ◽  
Geometrical Parameters ◽  
Hydrodynamic Properties ◽  
Anchor Agitator ◽  
Kinetics Of ◽  
Limiting Value

The stirring system of classical turbine agitator beside the anchor agitation system was studied from the point of view of the effect of their hydrodynamic properties on the kinetics of sunflower oil hydrogenation, It was found out that the anchor agitator makes up a higher gas hold-up than the turbine one and its efficiency from the view of reaction kinetics is higher. On changing the geometrical parameters of anchor agitator - by reducing its blade height - its hydrodynamic properties change considerably, and its efficiency decreases. The scaling-up of the stirring system did not manifest itself in the reaction rate in case of the turbine agitator. With the anchor agitator, the scaling-up resulted in the confirmation of its specific effect on the reaction kinetics, viz., on exceeding the limiting value of stirring frequency, the dramatic loss in efficiency took place.

scholarly journals Basic Ammonothermal Growth of GaN in Silver Lined Autoclave

2014 ◽  
Vol 70 (a1) ◽  
pp. C1416-C1416
Author(s):  
Siddha Pimputkar ◽  
Shinichiro Kawabata ◽  
James Speck ◽  
Shuji Nakamura
Keyword(s):  
Ammonia Solution ◽  
Hydride Vapor Phase Epitaxy ◽  
Total System ◽  
Material System ◽  
Large Area ◽  
Outward Diffusion ◽  
Growth Environment ◽  
Seed Crystals ◽  
System Pressure ◽  
Ammonothermal Growth

Gallium Nitride (GaN) and its alloys form a promising material system for optoelectronic and electronic devices. Heteroepitaxial growth of GaN on sapphire and SiC, while viable, introduces threading dislocations (between 1E8 – 1E11 cm^-2), mismatches in thermal expansion coefficients, and limitations on available growth orientations other than the polar, <0001> directions. With a push towards longer wavelengths, higher output powers at higher efficiencies with reduced droop for LEDs, non-polar and semi-polar oriented devices are becoming increasingly important, though need currently lacking, large area, bulk GaN substrates. A solution is the ammonothermal growth technique, which entails dissolving a GaN feedstock in a supercritical ammonia solution containing sodium (P < 270 MPa, T = 500–600 °C) and re-crystallizing the material on a GaN seed. Improvements in growth rate are needed to reduce cost and increase throughput. To that end, an ultra high purity (UHP) growth environment was created within a typical Ni-Cr superalloy autoclave by introducing a silver capsule. 40 basic ammonothermal growth runs were performed on hydride vapor phase epitaxy (HVPE) GaN seed crystals. The capsule design significantly reduced concentrations of transition metals in the GaN crystals (<1x1E17 cm^-3) while improving the transparency to α(450 nm) = 2.2 cm^-1. Total growth rates improved from 200 to 344130 μm/day for c-plane and from 34 to 4612 μm/day for m-plane growth. Degradation in crystal quality based on the full width at half maximum of the ω-rocking curve using X-ray diffraction when compared to the seed crystal was only observed for Ga-face growth on c-plane oriented seeds, presumably due to poor nucleation. Cracking in thick growth layers was observed due to strain originating from the HVPE seed crystals. Differences in the total system pressure profiles were analyzed and the observed pressure drop due to outward diffusion of hydrogen during growth was modeled.

scholarly journals Estimation of reliability of a interleaving PFC boost converter

2010 ◽  
Vol 7 (2) ◽  
pp. 205-216 ◽  
Author(s):  
Amer Gulam ◽  
Srinivasa Rao
Keyword(s):  
Power Supply ◽  
Boost Converter ◽  
Point Of View ◽  
Power Supplies ◽  
Total System ◽  
Front End ◽  
Higher Power ◽  
Conduction Mode ◽  
Very High ◽  
Continuous Conduction Mode

Reliability plays an important role in power supplies. For other electronic equipment, a certain failure mode, at least for a part of the total system, can often be employed without serious (critical) effects. However, for power supply no such condition can be accepted, since very high demands on its reliability must be achieved. At higher power levels, the continuous conduction mode (CCM) boost converter is preferred topology for implementation a front end with PFC. As a result, significant efforts have been made to improve the performance of high boost converter. This paper is one of the efforts for improving the performance of the converter from the reliability point of view. In this paper, interleaving boost power factor correction converter is simulated with single switch in continuous conduction mode (CCM), discontinuous conduction mode (DCM) and critical conduction mode (CRM) under different output power ratings. Results of the converter are explored from reliability point of view.

scholarly journals Solvent Influence on Selectivity in α-Pinene Oxide Isomerization Using MoO3-Modified Zeolite BETA

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1244
Author(s):  
Eva Vrbková ◽  
Eliška Vyskočilová ◽  
Miloslav Lhotka ◽  
Libor Červený
Keyword(s):  
Reaction Rate ◽  
Zeolite Beta ◽  
Point Of View ◽  
Impregnation Method ◽  
Modified Zeolite ◽  
Preferential Formation ◽  
Campholenic Aldehyde ◽  
Wide Range ◽  
Solvent Basicity ◽  
Positive Effect

Natural source turpentine is an available source of α-pinene oxide. This compound’s value is especially given by the possibility of producing important compounds campholenic aldehyde and trans-carveol. In this work, we would like to present the usage of MoO3-modified zeolite BETA in α-pinene oxide isomerization concerning campholenic aldehyde and trans-carveol formation using a wide range of solvents. Catalyst calcination temperature also influenced the reaction course (selectivity to desired compounds and reaction rate). MoO3-zeolite BETA was prepared by the wet impregnation method and characterized by different techniques. The use of polar aprotic solvents had the most positive effect on the reaction course. Solvent basicity and polarity considerably influenced the reaction rate and selectivity to particular products. The combination of high basicity and the high polarity was the most suitable for the studied reaction from the reaction rate point of view. Selectivity to campholenic aldehyde and trans-carveol was the most influenced by solvent basicity. Higher solvent basicity caused the preferential formation of trans–carveol, influence on selectivity to campholenic aldehyde formation was the opposite. The described catalyst may be used for α-pinene oxide rearrangement to both desired products dependently on the used solvent. Molybdenum offers an exciting alternative for previously described modifications of zeolites for this reaction.

scholarly journals A Novel Process of H2/CO2 Membrane Separation of Shifted Syngas Coupled with Gasoil Hydrogenation

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 590
Author(s):  
Weirong Huang ◽  
Xiaobin Jiang ◽  
Gaohong He ◽  
Xuehua Ruan ◽  
Bo Chen ◽  
...  
Keyword(s):  
Coal Gasification ◽  
Membrane Separation ◽  
Pressure Ratio ◽  
Stable Operation ◽  
Total System ◽  
Separation And Purification ◽  
Membrane Area ◽  
System Pressure ◽  
Compressor Power ◽  
Hydrogenation Reactor

A novel process of membrane separation for H2/CO2 of shifted syngas coupled with gasoil hydrogenation (NMGH) is proposed. First, a new process, with two-stage CO2-selective and one-stage H2-selective membranes, was developed to substitute the conventional PSA separation devices to remove CO2 and purify H2 in coal gasification refineries to reduce energy consumption and investment costs. Then, the process was coupled with gasoil hydrogenation and the recycled H2 produced by the hydrogenation reactor could be further purified by the H2-selective membrane, which increased the H2 concentration of the hydrogenation reactor inlet by about 11 mol.% compared with the conventional direct recycling process, and the total system pressure was reduced by about 2470 kPa. At the same time, this additional membrane separation and purification prevented the accumulation of CO/CO2 in the recycled H2, which ensured the activity of the catalyst in the reactor and the long-term stable operation of the devices. Further, parameters such as compressor power, PI (polyimide)/PEO (polyethylene oxide) membrane area, pressure ratio on both sides of the membrane, and purity of make-up H2 were optimized by sensitivity analysis. The results showed that, compared with the conventional method, the NMGH process simplified operations, significantly reduced the total investment cost by $17.74 million, and lowered the total annual costs by $1.50 million/year.

Staatliche Sozialpolitik und Staatstheorie / Social policy and the theory of the state

1976 ◽  
Vol 5 (2) ◽  
Author(s):  
Jürgen Krüger
Keyword(s):  
Social Policy ◽  
System Analysis ◽  
The State ◽  
Point Of View ◽  
Total System ◽  
Theoretical Approaches ◽  
Extended Approach ◽  
To Come ◽  
The One ◽  
And Function

AbstractThis article is a critical appraisal of the actual discussion of the role and function of social policy and social administration in Germany (FRG).Recent theoretical approaches, e. g. ‘the theory of the state’, are reviewed, and the ‘one-dimensionality’ of their categories with respect to evaluation of governmental activities in the field of social policy from a total systems point of view is criticized. The author argues in favour of an extended approach which should try to make use of the concept of ‘needs’ in order to reintroduce into the analysis the dimension of the personal system, to avoid the shortcomings criticized in the total system analysis.In so doing the characteristics of social policy and social administration in capitalistic societies, their dialectic quality, will become obvious; i. e. these policies have consequences, not only for the system in general, but also for the personal system (system of need-disposition).He propeses the application of the concept of social inequality for a systematic approach to social policy and social administration, to come to grips with their prerequisites, scope, and limitations.

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