Zinc carboxylic salts used as catalyst in the biodiesel synthesis by esterification and transesterification: Study of the stability in the reaction medium

2012 ◽  
Vol 449 ◽  
pp. 88-95 ◽  
Author(s):  
Deborath M. Reinoso ◽  
Daniel E. Damiani ◽  
Gabriela M. Tonetto
Keyword(s):  
Reaction Medium ◽  
Biodiesel Synthesis ◽  
The Stability

scholarly journals Performance of Iron-Functionalized Activated Carbon Catalysts (Fe/AC-f) on CWPO Wastewater Treatment

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 337
Author(s):  
Sara Mesa Medina ◽  
Ana Rey ◽  
Carlos Durán-Valle ◽  
Ana Bahamonde ◽  
Marisol Faraldos
Keyword(s):  
Wastewater Treatment ◽  
Activated Carbon ◽  
Landfill Leachate ◽  
Surface Composition ◽  
Treatment Plant ◽  
Reaction Medium ◽  
Pollutant Removal ◽  
Operating Conditions ◽  
Water Matrix ◽  
The Stability

Two commercial activated carbon were functionalized with nitric acid, sulfuric acid, and ethylenediamine to induce the modification of their surface functional groups and facilitate the stability of corresponding AC-supported iron catalysts (Fe/AC-f). Synthetized Fe/AC-f catalysts were characterized to determine bulk and surface composition (elemental analysis, emission spectroscopy, XPS), textural (N2 isotherms), and structural characteristics (XRD). All the Fe/AC-f catalysts were evaluated in the degradation of phenol in ultrapure water matrix by catalytic wet peroxide oxidation (CWPO). Complete pollutant removal at short reaction times (30–60 min) and high TOC reduction (XTOC = 80 % at ≤ 120 min) were always achieved at the conditions tested (500 mg·L−1 catalyst loading, 100 mg·L−1 phenol concentration, stoichiometric H2O2 dose, pH 3, 50 °C and 200 rpm), improving the results found with bare activated carbon supports. The lability of the interactions of iron with functionalized carbon support jeopardizes the stability of some catalysts. This fact could be associated to modifications of the induced surface chemistry after functionalization as a consequence of the iron immobilization procedure. The reusability was demonstrated by four consecutive CWPO cycles where the activity decreased from 1st to 3rd, to become recovered in the 4th run. Fe/AC-f catalysts were applied to treat two real water matrices: the effluent of a wastewater treatment plant with a membrane biological reactor (WWTP-MBR) and a landfill leachate, opening the opportunity to extend the use of these Fe/AC-f catalysts for complex wastewater matrices remediation. The degradation of phenol spiked WWTP-MBR effluent by CWPO using Fe/AC-f catalysts revealed pH of the reaction medium as a critical parameter to obtain complete elimination of the pollutant, only reached at pH 3. On the contrary, significant TOC removal, naturally found in complex landfill leachate, was obtained at natural pH 9 and half stoichiometric H2O2 dose. This highlights the importance of the water matrix in the optimization of the CWPO operating conditions.

A review of lignin hydrogen peroxide oxidation chemistry with emphasis on aromatic aldehydes and acids

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ajinkya More ◽  
Thomas Elder ◽  
Zhihua Jiang
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidative Degradation ◽  
Reaction Medium ◽  
Dicarboxylic Acids ◽  
Aromatic Aldehydes ◽  
Product Distribution ◽  
Reaction Conditions ◽  
Alkaline Conditions ◽  
The Stability ◽  
Oxidation Chemistry

Abstract This review discusses the main factors that govern the oxidation processes of lignins into aromatic aldehydes and acids using hydrogen peroxide. Aromatic aldehydes and acids are produced in the oxidative degradation of lignin whereas mono and dicarboxylic acids are the main products. The stability of hydrogen peroxide under the reaction conditions is an important factor that needs to be addressed for selectively improving the yield of aromatic aldehydes. Hydrogen peroxide in the presence of heavy metal ions readily decomposes, leading to minor degradation of lignin. This degradation results in quinones which are highly reactive towards peroxide. Under these reaction conditions, the pH of the reaction medium defines the reaction mechanism and the product distribution. Under acidic conditions, hydrogen peroxide reacts electrophilically with electron rich aromatic and olefinic structures at comparatively higher temperatures. In contrast, under alkaline conditions it reacts nucleophilically with electron deficient carbonyl and conjugated carbonyl structures in lignin. The reaction pattern in the oxidation of lignin usually involves cleavage of the aromatic ring, the aliphatic side chain or other linkages which will be discussed in this review.

scholarly journals Geometric Simulation Approach for Grading and Assessing the Thermostability of CALBs

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
B. Senthilkumar ◽  
D. Meshachpaul ◽  
R. Rajasekaran
Keyword(s):  
Surface Area ◽  
Structural Parameters ◽  
Conformational Sampling ◽  
Docking Analysis ◽  
Computational Docking ◽  
Highly Active ◽  
Structural Rigidity ◽  
Biodiesel Synthesis ◽  
The Stability ◽  
Thermostable Lipases

Candida antarcticalipase B (CALB) is a known stable and highly active enzyme used widely in biodiesel synthesis. In this work, the stability of native (4K6G) and mutant (4K5Q) CALB was studied through various structural parameters using conformational sampling approach. The contours of polar surface area and surface area of mutant CALB were 11357.67 Å2and 30007.4 Å2, respectively, showing an enhanced stability compared to native CALB with a statistically significantPvalue of < 0.0001. Moreover, simulated thermal denaturation of CALB, a process involving dilution of hydrogen bond, significantly shielded against different intervals of energy application in mutant CALB revealing its augmentation of structural rigidity against native CALB. Finally, computational docking analysis showed an increase in the binding affinity of CALB and its substrate (triglyceride) in mutant CALB with Atomic Contact Energy (ACE) of −91.23 kcal/mol compared to native CALB (ACE of −70.3 kcal/mol). The computational observations proposed that the use of mutant CALB (4K5Q) could serve as a best template for production of biodiesel in the future. Additionally, it can also be used as a template to identify efficient thermostable lipases through further mutations.

Scrutiny of Surface Plasmon Resonance Bands of Colloidal Cu and Cu-Ag Nanoparticles in Different Reaction Media for Stability Evaluation

2018 ◽  
Vol 52 ◽  
pp. 115-121
Author(s):  
Aung Chan Thar ◽  
Thaung Hlaing Win ◽  
Nyein Wint Lwin ◽  
Than Zaw Oo
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Chemical Reduction ◽  
Reaction Medium ◽  
Careful Examination ◽  
Metal Nanostructures ◽  
The Stability ◽  
Stability Time ◽  
Reaction Media

The copper nanoparticles (CuNPs) were developed in two different reaction media (distilled water (DW) and ethylene glycol (EG)) by chemical reduction method using two different stabilizers (polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP)). We carried out a careful examination of the time evolution of surface plasmon resonance (SPR) bands (specifically, peak positions and intensities) of colloidal CuNPs so as to evaluate their stability. In addition, the changing pattern of SPR peak positions and intensities during the stability time period was also investigated. Effects of stabilizer materials, stabilizer concentration, Ag capping and reaction medium on the stability of CuNPs colloids have been highlighted. The maximum stability of CuNPs is 4 hours with stabilizer PEG and is 4 days with PVP in DW. They, with PVP, extend up to 10 days in the different reaction medium (EG). The stability time of CuNPs in EG is further lengthened to 20 days in the presence of Ag capping (Cucore AgshellNPs). Thus a proper selection of the stabilizing/capping agent and the reaction medium is critical in determining the stability of CuNPs colloids. The benefits of stabilization of CuNPs for real world applications are immense and this study would help in examinning the stability of other novel plasmonic metal nanostructures.

scholarly journals Magnetic Nano-Sized Solid Acid Catalyst Bearing Sulfonic Acid Groups for Biodiesel Synthesis

2018 ◽  
Vol 16 (1) ◽  
pp. 923-929 ◽  
Author(s):  
Sezer Erdem ◽  
Beyhan Erdem ◽  
Ramis Mustafa Öksüzoğlu
Keyword(s):  
Magnetic Nanoparticles ◽  
Solid Acid Catalyst ◽  
Reaction Medium ◽  
Chlorosulfonic Acid ◽  
Acid Catalyst ◽  
Magnetic Core ◽  
Biodiesel Production ◽  
Silica Layer ◽  
Magnetic Iron Oxide Nanoparticles ◽  
Biodiesel Synthesis

AbstractIn our approach for magnetic iron oxide nanoparticles surface modification, the fabrication of an inorganic shell, consisting of silica by the deposition of preformed colloids onto the nanoparticle surface and functionalization of these particles, was realized. The magnetic nanoparticles, non-coated and coated with silica layer by Stöber method, are functionalized with chlorosulfonic acid. The magnetic nanoparticles (MNPs), in size of 10-13 nm, could be used as acid catalyst in biodiesel production and show superparamagnetic character. The prepared nanoparticles were characterized by different methods including XRD, EDX, FT-IR and VSM. The catalytic activity of the coated and non-coated solid acids was examined in palmitic acid-methanol esterification as an industrial reaction for biodiesel synthesis. Although thin silica layer results in only a minor obstacle with respect to magnetism, it can accelerate the mass transportation due to its relatively porous structure and magnetic core may be more stable in the acidic reaction medium by means of covering process. Accordingly, coating strategy can be efficient way for allowing applications of MNPs in acid catalyzed esterification.

scholarly journals Oligocat: Oligoesters as Pseudo-Homogenous Catalysts for Biodiesel Synthesis

Polymers ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 210
Author(s):  
Vitor Vlnieska ◽  
Aline Silva Muniz ◽  
Angelo Roberto dos Santos Oliveira ◽  
Maria Aparecida Ferreira César-Oliveira ◽  
Danays Kunka
Keyword(s):  
Conversion Rate ◽  
First Generation ◽  
Second Generation ◽  
Reaction Medium ◽  
Acid Catalyst ◽  
Biodiesel Production ◽  
European Federation ◽  
Alkyl Esters ◽  
Production Chain ◽  
Biodiesel Synthesis

Biodiesel production from first-generation feedstock has shown a strong correlation with the increase in deforestation and the necessity of larger areas for land farming. Recent estimation from the European Federation for Transport and Environment evidenced that since the 2000s decade, an area equal to the Netherlands was deforested to supply global biodiesel demand, mainly originating from first-generation feedstock. Nevertheless, biodiesel is renewable, and it can be a greener source of energy than petroleum. A promising approach to make biodiesel independent from large areas of farming is to shift as much as possible the biodiesel production chain to second and third generations of feedstock. The second generation presents three main advantages, where it does not compete with the food industry, its commercial value is negligible, or none, and its usage as feedstock for biodiesel production reduces the overall waste disposal. In this manuscript, we present an oligomeric catalyst designed to be multi-functional for second-generation feedstock transesterification reactions, mainly focusing our efforts to optimize the conversion of tallow fat and sauteing oil to FAME and FAEE, applying our innovative catalyst. Named as Oligocat, our catalyst acts as a Brønsted-Lowry acid catalyst, providing protons to the reaction medium, and at the same time, with the course of the reaction, it sequesters glycerol molecules from the medium and changes its physical phase during the transesterification reaction. With this set of properties, Oligocat presents a pseudo-homogenous behavior, reducing the purification and separation steps of the biodiesel process production. Reaction conditions were optimized applying a 42 factorial planning. The output parameter evaluated was the conversion rate of triacylglycerol to mono alkyl esters, measured through gel permeation chromatography (GPC). After the optimization studies, a conversion yield of 96.7 (±1.9) wt% was achieved, which allows classifying the obtained mono alkyl esters as biodiesel by ASTM D6751 or EN 14214:2003. After applying the catalyst in three reaction cycles, Oligocat still presented a conversion rate above 96.5 wt% and as well an excellent recovery rate.

Basic Ion Exchange Resins as Heterogeneous Catalysts for Biodiesel Synthesis

2010 ◽  
Vol 132 ◽  
pp. 220-227 ◽  
Author(s):  
Marisa G. Falco ◽  
Carlos D. Córdoba ◽  
María R. Capeletti ◽  
Ulises Sedran
Keyword(s):  
Ion Exchange ◽  
Heterogeneous Catalysts ◽  
Methyl Esters ◽  
Reaction Medium ◽  
Ion Exchange Resins ◽  
Reaction Products ◽  
Macroporous Resin ◽  
Biodiesel Synthesis ◽  
Exchange Resins ◽  
The Impact

Basic and acidic ion exchange resins were used as catalysts for the synthesis of biodiesel from soybean oil and methanol. The impact of reaction parameters like molar methanol/oil relationship, catalyst mass and reaction temperature were studied. The catalysts did not show deactivation and the reaction medium remained neutral. The performance of the resins was compared against reference catalysts (NaOH; MgO). A strongly basic macroporous resin was the most active catalyst and it was possible to reach 100 % selectivity to methyl esters. A series reaction mechanism was consistent with the evolutions of the intermediate reaction products.

Open discussion

1982 ◽  
Vol 99 ◽  
pp. 605-613
Author(s):  
P. S. Conti
Keyword(s):  
Buenos Aires ◽  
Large Mass ◽  
List Type ◽  
Common Phenomenon ◽  
Open Discussion ◽  
The Stability ◽  
Ring Nebulae

Conti: One of the main conclusions of the Wolf-Rayet symposium in Buenos Aires was that Wolf-Rayet stars are evolutionary products of massive objects. Some questions:–Do hot helium-rich stars, that are not Wolf-Rayet stars, exist?–What about the stability of helium rich stars of large mass? We know a helium rich star of ∼40 MO. Has the stability something to do with the wind?–Ring nebulae and bubbles : this seems to be a much more common phenomenon than we thought of some years age.–What is the origin of the subtypes? This is important to find a possible matching of scenarios to subtypes.

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