In search of efficient catalysts and appropriate reaction conditions for gas phase nitration of benzene

The present paper is dedicated to the development of a method for the nitrobenzene production using solid acid catalysts, as an alternative to industrial nitration, based on a mixture of concentrated acids. The influence of key parameters of the nitration process (temperature, reagent flow rate, nitrating agent concentration etc.) on the conversion of the initial substrate, the degree of decomposition of nitric acid and the quantity of resulting oxygenates was studied. Recommendations for the selection of effective catalytic systems (high content of Brønsted acid sites with Ho < −4, high specific surface and resistance to HNO3) were developed and the best conditions for process reactions (temperature 200 °C, aqueous solution of nitric acid with concentration of 30 wt%, “nitric acid:benzene” ratio = 0.76) were found. A method for regeneration of the catalytic activity without unloading the catalyst was proposed. As an example, MoO3/SiO2 sample was tested in a dual-mode nitration/regeneration process, which allowed us to increase the flow rates of reagents and obtain catalyst efficiency of up to STY = 4.09 g/(gcat · h). Several of the most promising catalysts (MoO3/SiO2, WO3/ZrO2 and Nafion/support composite) for the process were tested in identical conditions

The regularities of the formation of carbon nanostructures from hydrocarbons based on the composition of the reaction mixture

This paper presents the results of research on the regularities of the formation of carbon nanofibrous materials, as well as the influence of the composition of the model mixture of hydrocarbons S1-S4 on the morphological features and textural characteristics of the resulting carbon nanofibres (CNF). One of the most urgent issues faced by the oil and gas industry is how to increase the processing depth of associated petroleum gas (APG). In the Russian Federation alone, the annual economic losses from unutilised APG during processing are estimated at 2 billion dollars. It is known that the composition of APG can vary greatly, depending on the oil and gas field. In particular, the methane concentration, the main component of natural gas and associated gas, varies from 25 to 95 vol.%. In this study, we sought to identify the main factors that determine the morphology and structure of CNF, and to develop approaches in processing actual hydrocarbon mixtures to produce a carbon product with the desired or predictable characteristics. Such an approach can serve as a basis for resource-saving catalytic technology utilizing C1-C4 hydrocarbons that are currently disposed of as post-combustion flare gas

Effect of Cu(NO3)2 and Cu(CH3COO)2 Activating Additives on Combustion Characteristics of Anthracite and Its Semi-Coke

The process of anthracite and its semi-coke combustion in the presence of 5 wt.% (in terms of dry salt) additives of copper salts Cu(NO3)2 and Cu(CH3COO)2 was studied. The activating additives were introduced by an incipient wetness procedure. The ignition and combustion parameters for coal samples were examined in the combustion chamber at the heating medium temperatures (Tg) of 600-800 °C. The composition of the gaseous combustion products was controlled using an on-line gas analyzer. The fuel modification with copper salts was found to reduce the ignition delay time on average, along with a drop in the minimum ignition temperature Tmin by 138-277 °C. With an increase in Tg temperature, a significant reduction in the ignition delay time for the anthracite and semi-coke samples (by a factor of 6.7) was observed. The maximum difference in the ignition delay time between the original and modified samples of anthracite (ΔTi = 5.5 s) and semi-coke (ΔTi = 5.4 s) was recorded at a Tg temperature of 600 °C in the case of Cu(CH3COO)2. The emergence of micro-explosions was detected at an early stage of combustion via high-speed video imaging for samples modified by copper acetate. According to the on-line gas analysis data, the addition of copper salts permits one to reduce the volume of CO formed by 40% on average, providing complete oxidation of the fuel to CO2. It was shown that the introduction of additives promoted the reduction in the NOx emissions during the combustion of the anthracite and semi-coke samples