Addition Of Nitrogen Compounds Research Articles

Synthesis and characteristics of organotin-based catalysts for acetylene hydrochlorination

Organotin-based catalysts prepared by a facile and green synthesis route were used in the acetylene hydrochlorination reaction. In detail, organotin-based catalysts were directly synthesized by supporting both organotin and nitrogen compounds on a coal-based columnar activated carbon (AC) using both incipient wetness impregnation and calcination methods. Interestingly, upon addition of nitrogen compounds, the resultant (SnCl4 + C16H34Cl2Sn)/AC catalysts showed higher activity and stability when compared the its (SnCl4 + C16H34Cl2Sn + C2N4H4)/AC counterpart at 200 °C and a gas hourly space velocity (GHSV, C2H2 based) of 30 h−1. According to the results, organotin was demonstrated to be the active site, whereas the incorporation of nitrogen allowed partial mitigation of the loss of active components.

Experimental Study on Catalyst Deactivation by Nitrogen Compounds in a Hydroprocessing Reactor

The present work was devoted to study the effect of nitrogen compounds on hydrodesulfurization (HDS) activity of straight-run heavy naphtha loaded with thiophene, as a sulfiding model, onto a commercial \(\hbox {CoMo/Al}_{2}\hbox {O}_{3}\) in a fixed bed reactor. Parameter evaluation of ideal flow behavior in the reactor revealed that a catalyst bed packed with a particle diameter \(\,=\,316 \,\upmu \hbox {m}\) helps to eliminate wall, poor wetting and back-mixing effects. Results showed that sulfur removal would be enhanced by increasing temperature, and pressure, while liquid flow rate gives a different trend. The effect of nitrogen compounds on reaction rate constant was investigated (at temperature 320–380\(^{\circ }\hbox {C}\), pressure 30 bar, particle diameter \(316 \,\upmu \hbox {m}\), and \(\hbox {WHSV}= 2.5\,\hbox {h}^{-1}\)) with different concentrations of carbazole and pyridine, and a mixture with equal weight proportions of them. The experimental results were fitted to a first-order kinetics with correlation coefficients higher than 0.98. The experimental results confirmed that addition of nitrogen compounds does not affect the order of HDS reaction. Hydrodesulfurization efficiency was decreased from 93.4 to 73.3, 66.5, and 63.3% as the concentration of carbazole, pyridine, and a mixture of them increased from 0 to 100 ppmw, respectively. As observed from experimental results, the inhibiting effect of nitrogen compounds on HDS activity increased as the nitrogen concentration increased. The inhibition behavior was found to be highly nonlinear.

Electrokinetic Supply of Nutrients in Soil Bioremediation

Biodegradation processes in soil and groundwater often require a supply of nutrients. Pretreatment of soil with the addition of nitrogen compounds is often necessary to achieve the required C:N:P ratio. In addition, a uniform supply of these nutrients is essential for an effective technology. However, the difficulty in supplying the required nutrients increases in fine soil and for greater depths. Electrokinetics can be a cost-effective method for obtaining a more uniform distribution of nitrogen compounds. The laboratory scale tests were performed on natural soil that was supplied with three concentrations of ammonium nitrogen: 13 000 mg l−1, 1 000 mg l−1 and 100 mg l−1. The introduction of these nutrient solutions into the soil was performed by applying a DC electrical field for 27 days. The measurement of electrical parameters and the analysis of the cathode effluent permitted the monitoring of processes occurring in soil. The analysis of soil at the end of the experiment showed that the ammonium distribution in soil was relatively uniform and it was related to the initial concentration of the supplied liquid. The nitrate concentration was found to be the highest in the anode area. Results also showed that soil moisture content can be controlled by the electrokinetic method. Continuous measurements of electrical parameters showed the resistance changes in soil during nutrient application. Resistivity changes of the soil, especially in the cathode area, were observed.

Oxygen sensitivity of nitrogenase is not always a limiting factor of growth under nitrogen-fixing conditions inAzotobacter vinelandii

The effect of a combined nitrogen source to oxygen sensitive mutants was examined. For some oxygen sensitive mutants, oxygen sensitivity was not restored by the addition of nitrogen compounds to their medium. One of these mutants showed oxygen resistant nitrogenase activity similar to that of a wild strain. Results imply that oxygen sensitivity of nitrogenase is not always a limiting factor of growth under aerobic nitrogen-fixing conditions inAzotobactervinelandii.

Ammonia photoproduction byCyanospira rippkae cells ‘entrapped’ in dialysis tube

The photoproduction of ammonia by cells of the heterocystous cyanobacteriumCyanospira rippkae in the presence of the glutamine synthetase inhibitor, L-methionine D,L-sulfoximine (MSX), was investigated. The time course of changes in protein, pigment and carbohydrate concentrations and the C2H2-reducing activity of nitrogenase in MSX treated and untreated filament suspensions was also determined. The results show that nearly 40 h after MSX addition the cells are able to recover from the nitrogen starvation induced by the inhibitor by themselves, without the removal of MSX or the addition of nitrogenous compounds. Biliproteins, mobilized as a consequence of MSX addition, seem to play a key role in the process of cell recovery. These findings were exploited in a semicontinuous ammonia producing process with cells ‘immobilized’ in a dialysis tube photobioreactor.

NO x formation from nitrogen in fuel and air during turbulent diffusion combustion

To examine the comprehensive processes for NO x formation from nitrogen molecules in the air or in the nitrogen compounds in the fuel during turbulent diffusion combustion, radial and axial profiles of NO x , HCN and NH 3 were measured in turbulent diffusion flames with or without addition of nitrogen compound (NH 3 or NO) to the fuel or the air. High concentrations of HCN were detected in the propane flames without addition of nitrogen compounds which confirms the significance of NO formation by reactions related to HCN. Addition of NH 3 to the fuel results in higher concentrations of NO and HCN in the propane flames but HCN decays when mixed with excess air and decomposition of NO is observed in the fuel-rich region accompanying HCN formation. In CO+H 2 flames, however, scarcely any HCN is observed and the overall conversion rate of NH 3 into NO is very low as compared with that of propane flames. The behavior of the NO concentration observed in these flames is determined by its formation and destruction via HCN or NH x , coupled with mixing with air. The comprehensive reaction processes are also discussed.

NITROGEN MINERALIZATION IN SOLONETZIC SOIL SAMPLES AND SOME INFLUENCING FACTORS

A study was conducted on samples of an alkali Solonetz and a Solodic soil that occur in close proximity in the field to determine if factors other than the quantity of nitrogen might be responsible for the difference in the ability of the two soils to provide nitrogen to crops. The effect of altering the C/N ratio, heating, and the addition of nitrogenous compounds on nitrogen mineralization and CO2 evolution from A horizon samples was studied.Added sucrose stimulated the evolution of CO3 in the alkali Solonetz samples but added ammonium sulphate had no appreciable effect on the evolution of CO2. Heat caused a direct release of ammonium-nitrogen even from air-dry samples, and preheating caused a marked increase in ammonification during subsequent incubation. Both ammonification and nitrification took place quite effectively in samples of the alkali Solonetz soil to which a relatively simple organic nitrogen compound was added.The factor limiting nitrogen mineralization in alkali Solonetz soil appears to be the lack of readily decomposable organic nitrogen compounds.

Nitrogen Loss from Soils and Oxide Surfaces

IT has been reported1 that when a virgin soil is brought under cultivation, the percentage of total nitrogen usually falls off with time up to a limiting value. A loss of nitrogen from soils on the addition of nitrogenous compounds, especially when the conditions are favourable for oxidation, has also been observed by different investigators; but this phenomenon has been explained satisfactorily by Dhar and collaborators2, who have postulated that this type of nitrogen loss in soils is chiefly due to the formation and decomposition of the unstable ammonium nitrite produced in the processes of ammonification and nitrification. There is also the possibility of the reaction of nitrous acid on amines, amides and amino-acids which may sometimes be present in the soil or formed in the decomposition of soil organicsubstances. It has also been reported that soil loses nitrogen in the form of nitrogen gas much less when manured with sodium or potassium nitrate than when treated with ammonium sulphate, urea or other organic nitrogenous manures.