Formation of sulphur compounds in the hydrodenitrogenation of 2-methylquinoline, 2-methylpiperidine, indole, and isoquinoline on a nickel-tungsten catalyst in the presence of hydrogen sulphide

1983 ◽  
Vol 48 (12) ◽  
pp. 3413-3420 ◽  
Author(s):  
Mirko Černý ◽  
Antonín Trka
Keyword(s):  
Reaction Mechanism ◽  
Hydrogen Sulphide ◽  
Neutral Fraction ◽  
Degree Of Conversion ◽  
Pure Hydrogen ◽  
Sulphur Compounds ◽  
Nickel Tungsten

2-Methylquinoline, 2-methylpiperidine, indole, and isoquinoline were subjected to hydrodenitrogenation (HDN) on a sulphidized nickel-tungsten catalyst in an autoclave at 300 and 350 °C using pure hydrogen or a hydrogen-hydrogen sulphide mixture. The neutral fraction from the HDN of 2-methylquinoline and 2-methylpiperidine contained 40 and 90% sulphur compounds, respectively. The presence of hydrogen sulphide in the HDN of isoquinoline resulted in an enhanced fraction of the neutral moiety. A reaction mechanism is suggested for the HDN of 2-methylquinoline and 2-methylpiperidine in the presence of hydrogen sulphide, in which the latter contributes to the higher degree of conversion due to the formation of corresponding sulphur compounds.

Formation of sulphur compounds during the hydrodenitrogenation of aniline, cyclohexylamine, benzylamine, and 2-phenylethylamine on a nickel-tungsten catalyst in the presence of hydrogen sulphide

1984 ◽  
Vol 49 (10) ◽  
pp. 2387-2392 ◽  
Author(s):  
Mirko Černý ◽  
Antonín Trka
Keyword(s):  
Chemical Reaction ◽  
Hydrogen Sulphide ◽  
Degree Of Conversion ◽  
Direct Part ◽  
Sulphur Compounds ◽  
Nickel Tungsten

Hydrodenitrogenations of aniline, cyclohexylamine, benzylamine, and 2-phenylethylamine were performed on a sulphided nickel-tungsten catalyst at 300°C in an autoclave filled with hydrogen in the absence and in the presence of hydrogen sulphide. Due to the presence of hydrogen sulphide the degree of conversion increased from 0.9 to 3,6% for aniline and from 72 to 99% for benzylamine, and the fraction of neutral substances increased from 2.4 to 7% for cyclohexylamine and from 5.0 to 8.9% for 2-phenylethylamine. The neutral fractions contained cyclohexanethiol, thiobenzamide, 2-phenylethanethiol, and other sulphur compounds giving evidence that the increased degree of conversion of the amines was due to the hydrogen sulphide taking direct part in the chemical reaction.

Formation of sulfur compounds in the hydrodenitrogenation of piperidine, pyridine, 1-pentylamine and 1-pent-4-enylamine on a nickel-tungsten catalyst in the presence of hydrogen sulfide

1982 ◽  
Vol 47 (3) ◽  
pp. 928-935 ◽  
Author(s):  
Mirko Černý
Keyword(s):  
Hydrogen Sulfide ◽  
Reaction Pathway ◽  
Sulfur Compounds ◽  
Degree Of Conversion ◽  
Favourable Effect ◽  
Nitrogen Compounds ◽  
Pure Hydrogen ◽  
Nickel Tungsten

Hydrogenations of piperidine, pyridine, 1-pentylamine, and 1-pent-4-enylamine were carried out in an autoclave at 300°C on a sulfidized nickel-tungsten catalyst using either pure hydrogen or a mixture of hydrogen with hydrogen sulfide. Hydrogen sulfide was found to raise the degree of conversion of the starting substances and accelerate the hydrodenitrogenation by formation of sulfur compounds; 1-pentanethiol, di(1-pentyl)sulfide, 2-methylthiacyclopentane, thiacyclohexane and other sulfur compounds were detected in the reaction mixtures in the presence of hydrogensulfide. A reaction pathway is suggested of the hydrodenitrogenation of piperidine in the presence of hydrogen sulfide, accounting for the favourable effect of the latter on the hydrodenitrogenation of nitrogen compounds.

Formation of sulphur compounds in hydrodenitrogenation of quinoline, 1,2,3,4-tetrahydroquinoline, pyridine, piperidine and 1-pent-4-enylamine on a nickel-tungsten catalyst in the presence of hydrogen sulphide

1983 ◽  
Vol 48 (6) ◽  
pp. 1749-1758 ◽  
Author(s):  
Mirko Černý ◽  
Antonín Trka
Keyword(s):  
Hydrogen Sulphide ◽  
Reaction Scheme ◽  
Favourable Effect ◽  
Sulphur Compounds ◽  
Nickel Tungsten

Hydrodenitrogenation (HDN) of quinoline and 1,2,3,4-tetrahydroquinoline on a sulphided nickel-tungsten catalyst in the presence of hydrogen and of its mixture with hydrogen sulphide has been studied in an autoclave at 350 °C. The results show that hydrogen sulphide exhibits rate-accelerating effect on HDN of the above compounds by formation of sulphur compounds. It was found that neutral portion of the reaction mixture contains octahydro-2H-1-benzothiopyran, octahydro-1H-2-benzothiopyran, octahydro-2-methylbenzo(b)thiophene and other sulphur compounds. The reaction scheme for HDN of quinoline that accounts for favourable effect of hydrogen sulphide is proposed. In the neutral portion of the reaction mixture from HDN of piperidine and 1-pent-4-enylamine in the presence of hydrogen sulphide further sulphur-containing compounds were identified.

The effect of sulphur compounds on hydrodenitrogenation of nitrogen compounds on a nickel-tungsten catalyst

1982 ◽  
Vol 47 (5) ◽  
pp. 1465-1469 ◽  
Author(s):  
Mirko Černý
Keyword(s):  
Hydrogen Sulphide ◽  
Nitrogen Compounds ◽  
Sulphur Compounds ◽  
Nickel Tungsten

Hydrodenitrogenation of pyridine on a sulphided NiO-WO3/Al2O3 catalyst has been studied in the presence of ethanethiol, propanethiol, thiophene and hydrogen sulphide and the amount of pentane, 1-methylpiperidine, 1-ethylpiperidine and piperidine has been determined. It was found that in the presence of all the sulphur compounds but hydrogen sulphide, the conversion of pyridine was lower than in their absence. The presence of hydrogen sulphide increased pyridine conversion.

The reaction of μ-oxo-bis(phthalocyaninato)iron(III) with hydrogen sulphide in the presence of pyridine: Evidence for axial coordination of dichloromethane

2005 ◽  
Vol 09 (03) ◽  
pp. 198-205 ◽  
Author(s):  
Fabrizio Monacelli ◽  
Elisa Viola
Keyword(s):  
Reaction Mechanism ◽  
Linear Function ◽  
Rate Constant ◽  
Hydrogen Sulphide ◽  
Stoichiometric Ratio ◽  
First Order ◽  
Axial Coordination ◽  
Elementary Sulphur ◽  
Increasing Function ◽  
Limiting Value

The oxo-bridged complex ( py ) FePc - O - FePc ( py ) ( py = pyridine , Pc = phthalocyaninato dianion) reacts in dichloromethane with hydrogen sulphide giving elementary sulphur and the reduced ( py )2( FePc ) complex in the stoichiometric ratio 1:1. Under excess py and H2S , the reaction is first-order and the rate constant at a given py concentration is an increasing function of the reducing agent concentration, with asymptotic tendency to a limiting value. This latter depends on the pyridine concentration being higher the lower is the base concentration. When the reaction is carried out in pure pyridine, the rate constant is, instead, a strictly linear function of [ H2S ], with zero intercept. A reaction mechanism is proposed where the dichloromethane is directly involved in the axial coordination about the iron centers and H2S competes efficiently with both pyridine and solvent.

Comparison of Numerical Combustion Models for Hydrogen and Hydrogen-Rich Syngas Applied for Dry-Low-NOx-Micromix-Combustion

2016 ◽  
Author(s):  
H. H.-W. Funke ◽  
N. Beckmann ◽  
J. Keinz ◽  
S. Abanteriba
Keyword(s):  
Reaction Mechanism ◽  
Gas Turbines ◽  
Combustion Process ◽  
Computational Effort ◽  
Hydrogen Combustion ◽  
Combustion Stability ◽  
Research Approach ◽  
Pure Hydrogen ◽  
Nox Emissions ◽  
Combustion Models

The Dry-Low-NOx (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing. Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, CFD analyses are validated towards experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOx emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. For pure hydrogen combustion a one-step global reaction is applied using a hybrid Eddy-Break-up model that incorporates finite rate kinetics. The model is evaluated and compared to a detailed hydrogen combustion mechanism derived by Li et al. including 9 species and 19 reversible elementary reactions. Based on this mechanism, reduction of the computational effort is achieved by applying the Flamelet Generated Manifolds (FGM) method while the accuracy of the detailed reaction scheme is maintained. For hydrogen-rich syngas combustion (H2-CO) numerical analyses based on a skeletal H2/CO reaction mechanism derived by Hawkes et al. and a detailed reaction mechanism provided by Ranzi et al. are performed. The comparison between combustion models and the validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The Flamelet Generated Manifolds method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry. Especially for reaction mechanisms with a high number of species accuracy and computational effort can be balanced using the FGM model.

scholarly journals Biodegradation of the xenobiotic organic disulphide 4,4′-dithiodibutyric acid by Rhodococcus erythropolis strain MI2 and comparison with the microbial utilization of 3,3′-dithiodipropionic acid and 3,3′-thiodipropionic acid

Microbiology ◽  
2010 ◽  
Vol 156 (4) ◽  
pp. 1221-1233 ◽  
Author(s):  
Jan Hendrik Wübbeler ◽  
Nadine Bruland ◽  
Milena Wozniczka ◽  
Alexander Steinbüchel
Keyword(s):  
Carbon Source ◽  
Succinic Acid ◽  
Hydrogen Sulphide ◽  
Rhodococcus Erythropolis ◽  
Building Blocks ◽  
Bacterial Strains ◽  
Sulphur Compounds ◽  
Promising Alternative ◽  
Microbial Utilization ◽  
Broad Variety

Application of the non-toxic 3,3′-thiodipropionic acid (TDP) and 3,3′-dithiodipropionic acid (DTDP) as precursors for the microbial production of polythioesters (PTEs), a class of biologically persistent biopolymers containing sulphur in the backbone, was successfully established previously. However, synthesis of PTEs containing 4-mercaptobutyrate (4MB) as building blocks could not be achieved. The very harmful 4MB is not used as a PTE precursor or as the carbon source for growth by any known strain. As a promising alternative, the harmless oxidized disulfide of two molecules of 4MB, 4,4′-dithiodibutyric acid (DTDB), was employed for enrichments of bacterial strains capable of biodegradation. Investigation of novel precursor substrates for PTEs and comparison of respective strains growing on TDP, DTDP and DTDB as sole carbon source was accomplished. A broad variety of bacteria capable of using one of these organic sulphur compounds were isolated and compared. TDP and DTDP were degraded by several strains belonging to different genera, whereas all DTDB-utilizing strains were affiliated to the species Rhodococcus erythropolis. Transposon mutagenesis of R. erythropolis strain MI2 and screening of 7500 resulting mutants yielded three mutants exhibiting impaired growth on DTDB. Physiological studies revealed production of volatile hydrogen sulphide and accumulation of significant amounts of 4MB, 4-oxo-4-sulphanylbutanoic acid and succinic acid in the culture supernatants. Based on this knowledge, a putative pathway for degradation of DTDB was proposed: DTDB could be cleaved into two molecules of 4MB, followed by an oxidation yielding 4-oxo-4-sulphanylbutanoic acid. A putative desulphydrase probably catalyses the abstraction of sulphur, thereby generating succinic acid and hydrogen sulphide.

scholarly journals On the Formation of COS from H2S and CO2 in the Presence of Zeolite/Salt Compounds

1998 ◽  
Vol 16 (7) ◽  
pp. 577-581 ◽  
Author(s):  
Wolfgang Lutz ◽  
Andreas Seidel ◽  
Bruno Boddenberg
Keyword(s):  
Carbon Dioxide ◽  
Ion Exchange ◽  
Hydrogen Sulphide ◽  
Calcium Ions ◽  
Gaseous Mixture ◽  
Degree Of Conversion ◽  
Low Level ◽  
Sodium Cations

A gaseous mixture of hydrogen sulphide and carbon dioxide (20% H2S, 80% CO2) was brought into contact at 25°C with NaY and NaX zeolites in an as-synthesized form as well as after modification by the inclusion of salts (NaCl, NaBr) in the small cages of the aluminosilicate framework and ion exchange with aqueous CaCl2 solution. At small contact times (5 h), the degree of conversion of H2S according to the reaction H2S + CO2 → COS + H2O by the various samples was found to follow the sequence NaY/NaCl ≈ NaY/NaBr ≈ NaX/NaCl(CaCl2) < NaY « NaX/NaCl ≈ NaX. Long-term runs with NaY and NaY/NaBr revealed that the latter zeolite retained a very low level of H2S conversion for contact times as long as 250 h. It is concluded that such low H2S conversion requires the absence of low-coordinated sodium cations in the supercages or their replacement by calcium ions, and blocking of the β-cages with salt anions.

Anaerobic 35°C and 55°C Treatment of a BCTMP/TMP Effluent: Sulphur Management Strategies

1994 ◽  
Vol 29 (5-6) ◽  
pp. 433-445 ◽  
Author(s):  
R. J. Stephenson ◽  
R. M. R. Branion ◽  
K. L. Pinder
Keyword(s):  
Hydrogen Sulphide ◽  
Effective Means ◽  
Management Strategies ◽  
Sulphate Reduction ◽  
Anaerobic Sludge ◽  
Thermomechanical Pulp ◽  
Treatment Efficiency ◽  
Sulphur Compounds ◽  
Experimental Apparatus ◽  
Molybdenum Addition

Pulp manufacture uses sulphur in a variety of forms and these sulphur compounds ultimately end up in the effluent. Under anaerobic conditions, sulphite and sulphate are reduced to sulphide, presenting problems of toxicity, odour, corrosion, and reduced methane yields and treatment efficiencies. The fate of these inorganic sulphur compounds in a bleached chemi-thermomechanical pulp/thermomechanical pulp (BCTMP/TMP) effluent mixture was examined in two phase anaerobic reactors at 35°C and 55°C. The following sulphur management strategies were investigated: 1) controlling the pH of the acidogenic reactor, 2) inhibiting the sulphur reducing bacteria via molybdenum addition to the feed tank, and 3) stripping the hydrogen sulphide dissolved in the methane phase reactor liquor by recycling hydrogen sulphide-free off gas. The laboratory scale experimental apparatus consisted of upflow anaerobic sludge bed pre-treatment or acidogenic reactors followed by hybrid upflow anaerobic sludge bed/fixed film methanogenic reactors. At 35°C, controlling the pH of the acidogenic reactors with sodium carbonate from 5.5 (uncontrolled) to 8.0 in order to shift the formed sulphide species to the less toxic ionic form appeared to be ineffective in promoting wastewater treatment efficiency. Molybdenum addition to the wastewater at levels from 0.1 to 1.0 mM was effective at 1.0 mM in retarding sulphate reduction or sulphide formation. Hydrogen sulphide stripping, using ferric chloride scrubbed and recycled off gas, appeared to be the most effective means of sulphur management for this type of wastewater under these conditions. Tbermophilic 55°C anaerobic treatment was also studied using the same effluent, inocula and sulphur management strategies. Overall, both the treatment efficiency and the sulphate reduction were lower for the thermophilic runs compared to the mesophilic runs. Raising the acidogenic phase reactor pH from 7.0 to 7.5 to 8.0 appeared to have no significant effect on organic carbon removal efficiency or on sulphate reduction. Molybdenum inhibition of sulphur reduction was not as marked as for the 1.0 mM level at 35°C, perhaps due to the already low baseline sulphate reduction efficiency at 55°C. Stripping hydrogen sulphide from the reactor liquor helped to promote the treatment efficiency and lowered the sulphide and sulphate levels. Similar to the 35°C study, sulphide removal by gas stripping appeared to be the most effective means of sulphur management

Sign in / Sign up

Export Citation Format

Share Document