scholarly journals Photocatalytic Selective Oxidation of Ammonia in a Semi-Batch Reactor: Unravelling the Effect of Reaction Conditions and Metal Co-Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 209
Author(s):  
Elnaz Bahadori ◽  
Francesco Conte ◽  
Antonio Tripodi ◽  
Gianguido Ramis ◽  
Ilenia Rossetti
Keyword(s):  
Batch Reactor ◽  
Ammonia Concentration ◽  
Flame Spray ◽  
Reaction Conditions ◽  
Co Catalysts ◽  
Vis Spectroscopy ◽  
Optimum Ph ◽  
Ammonia Conversion ◽  
Selective Formation ◽  
Oxidation Of Ammonia

Photocatalysis has been used for the oxidation of ammonia/ammonium in water. A semibatch photoreactor was developed for this purpose, and nanostructured TiO2-based materials, either commercial P25 or prepared by flame spray pyrolysis (FSP), were used as catalysts. In the present work, we investigated the effect of (i) metal co-catalysts, (ii) pH, and (iii) ammonia concentration on the efficiency of oxidation and on the selectivity to the undesired overoxidation byproduct, i.e., nitrites and nitrates. Several metals were added to both titania samples, and the physicochemical properties of every sample were studied by XRD, BET, and UV-Vis spectroscopy. The pH, which was investigated in the range of 2.5–11.5, was the most important parameter. The optimum pH values, resulted as 11.5 and 4.8 for P25 and FSP respectively, matching the best compromise between an acceptable conversion and a limited selectivity toward nitrite and nitrate formation. For both titania samples (P25 and FSP), ammonia conversion vs. nitrite and nitrate formation were highly dependent on the pH. At pH ≥ 9, the initial rate of photooxidation was high, with selective formation of overoxidized byproducts, whereas, at a more acidic pH, the conversion was lower, but the selectivity toward nitrogen formation was higher. P25 samples added with noble metal co-catalysts (0.1 mol% Ag, Au, Pd, Pt) at pH = 11.5 remarkably increased the selectivity to nitrite and nitrate, while, in the case of FSP samples (pH = 4.8), the co-catalysts increased the selectivity toward N2 with respect to the unpromoted catalyst and also the conversion in the case of Au and Pt. Reactivity was discussed, leading to the proposing of a mechanism that correlates the activity with either surface adsorption (depending of the surface charge of the catalyst and on pH) or the homogeneous reactivity of oxidizing species.

Gold Catalyzed Hydroamination of Propargylic Alcohols: Controlling Divergent Reaction Pathways to Access 1,3-Aminoalcohols, 3-Hydroxyketones or 3-Aminoketones

2018 ◽  
Author(s):  
Victor Laserna ◽  
Tom Sheppard
Keyword(s):  
Gold Catalysis ◽  
Reaction Pathways ◽  
High Yield ◽  
Reaction Conditions ◽  
Propargylic Alcohols ◽  
Catalytic Quantity ◽  
Selective Formation ◽  
General Method

A versatile approach to the valorization of propargylic alcohols is reported, enabling controlled access to three different products from the same starting materials. Firstly, a general method for the hydroamination of propargylic alcohols with anilines is described using gold catalysis to give 3-hydroxy imines with complete regioselectivity. These 3-hydroxyimines can be reduced to give 1,3-aminoalcohols with high syn seletivity. Alternatively, by using a catalytic quantity of aniline, 3-hydroxyketones can be obtained in high yield directly from propargylic alcohols. Further manipulation of the reaction conditions enables the selective formation of 3-aminoketones via a rearrangement/hydroamination pathway.<br>

A review of sustainable lignocellulose biorefining applying (natural) deep eutectic solvents (DESs) for separations, catalysis and enzymatic biotransformation processes

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ana Bjelić ◽  
Brigita Hočevar ◽  
Miha Grilc ◽  
Uroš Novak ◽  
Blaž Likozar
Keyword(s):  
Special Section ◽  
Cost Effective ◽  
Deep Eutectic Solvents ◽  
Reaction Conditions ◽  
Co Catalysts ◽  
Biomass Fractionation ◽  
Functional Step ◽  
Natural Deep Eutectic Solvents ◽  
Economic Need ◽  
Molecular Compounds

AbstractConventional biorefinery processes are complex, engineered and energy-intensive, where biomass fractionation, a key functional step for the production of biomass-derived chemical substances, demands industrial organic solvents and harsh, environmentally harmful reaction conditions. There is a timely, clear and unmet economic need for a systematic, robust and affordable conversion method technology to become greener, sustainable and cost-effective. In this perspective, deep eutectic solvents (DESs) have been envisaged as the most advanced novel polar liquids that are entirely made of natural, molecular compounds that are capable of an association via hydrogen bonding interactions. DES has quickly emerged in various application functions thanks to a formulations’ simple preparation. These molecules themselves are biobased, renewable, biodegradable and eco-friendly. The present experimental review is providing the state of the art topical overview of trends regarding the employment of DESs in investigated biorefinery-related techniques. This review covers DESs for lignocellulosic component isolation, applications as (co)catalysts and their functionality range in biocatalysis. Furthermore, a special section of the DESs recyclability is included. For DESs to unlock numerous new (reactive) possibilities in future biorefineries, the critical estimation of its complexity in the reaction, separation, or fractionation medium should be addressed more in future studies.

scholarly journals Granulicoccus phenolivorans gen. nov., sp. nov., a Gram-positive, phenol-degrading coccus isolated from phenol-degrading aerobic granules

2007 ◽  
Vol 57 (4) ◽  
pp. 730-737 ◽  
Author(s):  
Abdul Majid Maszenan ◽  
He Long Jiang ◽  
Joo-Hwa Tay ◽  
Peter Schumann ◽  
Reiner M. Kroppenstedt ◽  
...  
Keyword(s):  
Batch Reactor ◽  
Rrna Gene ◽  
Aerobic Granules ◽  
New Genus And Species ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Optimum Ph ◽  
Phenolic Wastewater ◽  
Ph Range ◽  
Capsular Material

A Gram-positive bacterium, designated strain PG-02T, was isolated by serial dilution from aerobic granules obtained from a laboratory-scale sequencing batch reactor for bioremediation of phenolic wastewater. Strain PG-02T grew axenically as cocci and is an oxidase-negative and catalase-positive, non-motile facultative anaerobe. It does not reduce nitrate and grows between 15 and 37 °C, with an optimum temperature of 30 °C. The pH range for growth is between 5.0 and 8.5, with an optimum pH of 7.0. Strain PG-02T contains type A3γ peptidoglycan (ll-A2pm←Gly with alanine at position 1 of the peptide subunit). The G+C content of the DNA is 69 mol%. Menaquinone MK-9(H4) was the major isoprenoid quinone. The polar lipids included diphosphatidylglycerol and phosphatidylglycerol, while 13-methyltetradecanoic acid (i-C15 : 0) and 1,1-dimethoxy-iso-pentadecane (i-C15 : 0 DMA) were the major components in whole-cell methanolysates. PG-02T stained positively for intracellular polyphosphate granules but not poly-β-hydroxyalkanoates. It produces capsular material and possesses an autoaggregation capability. Phenotypic and 16S rRNA gene sequence analyses showed that PG-02T differed from its closest phylogenetic relatives, namely members of the suborder Propionibacterineae, which includes the genera Tessaracoccus, Microlunatus, Luteococcus, Micropruina, Propionibacterium, Propioniferax, Nocardioides, Friedmanniella and Aeromicrobium, and that it should be placed in a new genus and species as Granulicoccus phenolivorans gen. nov., sp. nov. The type strain of Granulicoccus phenolivorans is PG-02T (=ATCC BAA-1292T=DSM 17626T).

scholarly journals Immobilization of alpha-amylase produced by Bacillus circulans GRS 313

2003 ◽  
Vol 46 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Gargi Dey ◽  
Singh Bhupinder ◽  
Rintu Banerjee
Keyword(s):  
Calcium Alginate ◽  
Immobilized Enzyme ◽  
Fold Increase ◽  
Alginate Beads ◽  
Hydrolysis Kinetics ◽  
Initial Activity ◽  
Reaction Conditions ◽  
Bead Size ◽  
Optimum Ph ◽  
Optimum Ph And Temperature

A maltooligosaccharide-forming amylase from B circulans GRS 313 was immobilized by entrapment in calcium alginate beads. The immobilized activity was affected by the size of the bead and bead size of 2mm was found to be most effective for hydrolysis. Kinetics constants, Km and Vmax were estimated and were found to be affected by the bead size. The catalytic activity of the enzyme was studied in presence of various starchy residues and metal ions. HgCl2, CuSO4 and FeCl3 caused inhibition of the enzyme. The reaction conditions, pH and temperature, was optimized using response surface methodology. At the optimum pH and temperature of 4.9 and 57ºC, the apparent activity was 25.6U/g of beads, resulting in almost 2-fold increase in activity. The immobilized enzyme showed a high operational stability by retaining almost 85% of the initial activity after seventh use.

scholarly journals Stochastic modeling of microstructure of homopolymers and copolymers in batch reactor

2020 ◽  
Vol 9 (2) ◽  
pp. e04921930
Author(s):  
Matheus Dias Carvalho ◽  
Jorge David Alguiar Beliido ◽  
Antonio Marcos de Oliveira Siqueira ◽  
Júlio Cesar Costa Campos
Keyword(s):  
Stochastic Modeling ◽  
Chemical Reactions ◽  
Batch Reactor ◽  
Polymer Chains ◽  
Stochastic Methods ◽  
Batch Reactors ◽  
Straight Chain ◽  
Reaction Conditions ◽  
C Language ◽  
Methyl Styrene

Find the microstructure of the product generated in a reaction of polymerization is desirable from a material science standpoint, due to the association between the microstructure and the physical properties. For the science of this fact, this paper aims to use stochastic modeling to obtain the microstructure and key information from a set of polymer chains generated during a reaction. From this data, the present article contributes to the minimization of experimental expenses, besides the saving of time, since no experiments are necessary to discover the characteristics of the polymer obtained under certain reaction conditions. This information cannot be found by other usual methodologies for modeling chemical reactions, such as the deterministic form. Also, from a given desired structure, the initial concentration and temperature conditions for forming that product can be obtained. This study was conducted based on Monte Carlo stochastic methods, by which we seek to replicate the randomness present in chemical reactions. The algorithm created in C ++ language determines the variation of the number of molecules of each species with time, besides the chemical composition, the sequence of mere and size of the generated chains. This approach applies to straight-chain homopolymerizations and copolymerizations. In this paper, we studied the polymerization in styrene batch reactors to form polystyrene, in addition to the copolymerization of styrene with alpha-methyl styrene. These simulations were characterized by forming chains with small blocks of monomers.

Kinetics of Glycerol Biotransformation to Dihydroxyacetone by Immobilized Gluconobacter oxydans and Effect of Reaction Conditions

2007 ◽  
Vol 72 (9) ◽  
pp. 1269-1283 ◽  
Author(s):  
Jiří Raška ◽  
František Skopal ◽  
Karel Komers ◽  
Jaroslav Machek
Keyword(s):  
Yeast Extract ◽  
Batch Reactor ◽  
Gluconobacter Oxydans ◽  
Poly Vinyl Alcohol ◽  
Glycerol Concentration ◽  
Reaction Conditions ◽  
Extract Concentration ◽  
Autocatalytic Model ◽  
Kinetics Of ◽  
Reaction Schemes

Biotransformation of glycerol to 1,3-dihydroxyacetone was carried out in an isothermal isochoric batch reactor with Gluconobacter oxydans immobilized in poly(vinyl alcohol) gel capsules. The reaction course was described with a three-step kinetic model. Two reaction schemes were proposed and compared with 8 kinetic experiments at 25 °C. The experimental dependences of glycerol and dihydroxyacetone concentrations on reaction time were simulated very well by the autocatalytic model. The effects of reaction temperature and initial concentrations of yeast extract and glycerol were studied. Temperature 25-30 °C, initial yeast extract concentration 2-4 g l-1 and initial glycerol concentration 20-50 g l-1 were found as optimal. The determined rate constants can be used to advantage for industrial production of dihydroxyacetone from glycerol.

Intensification of the Production of 2-Ethyl-Hexyl Acrylate: Batch Kinetics and Reactive Distillation

2018 ◽  
Vol 16 (7) ◽  
Author(s):  
Vivek D. Talnikar ◽  
Onkar A. Deorukhkar ◽  
Amit Katariya ◽  
Yogesh S. Mahajan
Keyword(s):  
Kinetic Model ◽  
Acrylic Acid ◽  
Process Development ◽  
Reactive Distillation ◽  
Batch Reactor ◽  
Process Intensification ◽  
Complete Conversion ◽  
Reaction Conditions ◽  
Batch Mode ◽  
Batch Kinetics

Abstract The reaction of acrylic acid and 2-ethyl-1 hexanol was explored in this work with the intent of process intensification. In order to assess the effect of important parameters on the course of reaction, this work initially conducted batch reactor experiments. Reaction conditions in the batch reactor for a specific conversion (~ 30 %) were obtained. A kinetic model was then obtained through regression to arrive at a rate expression that is later used in process development. Experiments were performed in the reactive distillation (RD) environment in batch mode, which showed substantial increase in conversion (~ 80 %) indicating the applicability of RD. Further, this work performed simulation in the RD environment to assess process intensification. Simulations show that it is possible to obtain complete conversion of the acid.

scholarly journals Evaluation of dolomite as catalyst in the transesterification reaction using palm oil (RBD)

DYNA ◽  
2019 ◽  
Vol 86 (209) ◽  
pp. 180-187
Author(s):  
Stephanie Alexa Ñústez Castaño ◽  
Duvan Oswaldo Villamizar Castro ◽  
Edgar Mauricio Vargas Solano
Keyword(s):  
Palm Oil ◽  
Batch Reactor ◽  
Methyl Esters ◽  
Average Pore Size ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Average Pore ◽  
X Ray ◽  
Rbd Palm Oil ◽  
Methyl Ester Content

In this study, the catalytic activity of dolomite was evaluated for the transesterification of Colombian RBD palm oil with methanol, carried out in a batch reactor at 333,15K and 600rpm. The activated dolomites (calcined at 1073.15K for 2h) were characterized by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Hammett indicators method, and quantification of the surface area, average pore size and average pore volume BET. The influence of reaction variables such as catalyst amount (%wt /wt) and methanol / palm oil molar ratio (mole/mole) was investigated. Under the suitable reaction conditions, the amount of calcined dolomite equal to 4% (wt /wt) based on the weight of oil, the methanol-oil molar ratio equal to 9:1, and the reaction time = 1h, the methyl ester content of 82.67% of fatty acid methyl esters (FAME) can be achieved.

Oxidation of ammonia using modified TiO2 catalyst and UV-VIS irradiation

2012 ◽  
Vol 66 (6) ◽  
Author(s):  
Łukasz Kowalczyk ◽  
Małgorzata Szynkowska
Keyword(s):  
Titanium Dioxide ◽  
Tio2 Catalyst ◽  
Physico Chemical ◽  
Ammonia Conversion ◽  
The Impact ◽  
Oxidation Of Ammonia

AbstractThe impact of UV and VIS irradiation and specific nitrogen modification on a 5%Cu/5%TiO2/SiO2 catalyst in the course of oxidation of ammonia was investigated. It was demonstrated that both UV and VIS irradiation increased the conversion of the reactant in the reaction studied. Due to a good distribution of titanium dioxide and copper on the surface of the support, higher ammonia conversion was achieved. Physico-chemical characterisation of the catalysts studied using methods such as BET, SEM-EDS, TPD (NH3), and TPD (CO2) was carried out.

scholarly journals CO2 Capture by Alkaline Carbonation as an Alternative to a Circular Economy

2020 ◽  
Vol 10 (3) ◽  
pp. 863
Author(s):  
Dalia Santa Cruz-Navarro ◽  
Violeta Mugica-Álvarez ◽  
Mirella Gutiérrez-Arzaluz ◽  
Miguel Torres-Rodríguez
Keyword(s):  
Co2 Capture ◽  
Atmospheric Pressure ◽  
Batch Reactor ◽  
Morphological Characterization ◽  
Raw Material ◽  
Alkaline Solutions ◽  
Reaction Conditions ◽  
Industrial Enterprises ◽  
Metal Carbonates ◽  
Industrial Use

In order to combat global warming and climate change in a sustainable way, it is necessary to capture the anthropogenic CO2 emitted by different industrial sources and use it as a raw material to obtain a matrix of products for industrial use, such as metal carbonates. Therefore, this work presents the results of CO2 capture and conversion into carbonates using Sr and Ba alkaline solutions in a semi-continuous batch reactor. The results indicate that the effects of morphological characterization, purity of solids, and reaction time at ambient temperature and atmospheric pressure conditions is an inexpensive alternative process that is easily implemented in small industrial enterprises. The results yielded a 40% conversion of CO2 at the best reaction conditions with an aqueous solution of Sr(OH)2.

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