RESEARCH OF POSSIBILITY OF PROCESSING PETROLEUM COKE  WITH INCREASED VOLATILE SUBSTANCES INTO ACTIVATED CARBONS

In present work, study to obtain granulated active carbon based on industrial petroleum coke of the CEL grade (coke with an increased content of volatile substances) produced in delayed coking unit have been conducted. The production of activated carbons was carried out by preliminary carbonization of coke at a temperature of 500-800 °C, followed by activation in a water vapor atmosphere at a temperature of 850-900 °C. In addition, tests were carried out on the effect of impregnation of the initial coke with aqueous solutions of chemical activators (sodium hydroxide, potassium carbonate, phosphoric acid) on the efficiency of heat treatment and characteristics of the porous structure of the resulting sorbent. The use of sodium hydroxide as an activating agent increases the reactivity of the sample, but the microporous structure does not develop. Using potassium carbonate as the activating solution and increasing the carbonization temperature to 800 °C causes an increase in the degree of burning from 28 to 44 %. However, activation of the resulting carbonizates with superheated steam leads to a 97-98 % burn-out of the samples due to a sharp increase in reactivity. It was shown that activated carbon obtained on the base of petroleum coke with an increased content of volatile substances by preliminary impregnation with an aqueous solution of phosphoric acid (concentration 17 wt.%), filtration and drying, followed by carbonization at a temperature of 800 °C in an inert atmosphere and activation in water vapor medium at a temperature of 850-900 °С has a sufficiently high specific surface of micropores (up to 430 m2/g) and other characteristics of the porous structure. Thus, the proposed method can serve as one of the ways to expand the qualified use of petroleum coke.

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Investigation of the porous structure of activated carbons prepared by pyrolysis of agricultural by-products in a stream of water vapor

Carbon ◽

10.1016/0008-6223(92)90154-o ◽

1992 ◽

Vol 30 (5) ◽

pp. 721-727 ◽

Cited By ~ 57

Author(s):

K. Gergova ◽

A. Galushko ◽

N. Petrov ◽

V. Minkova

Keyword(s):

Water Vapor ◽

Porous Structure ◽

Activated Carbons ◽

By Products

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Computer Analysis of the Effect of Activation Temperature on the Microporous Structure Development of Activated Carbon Derived from Common Polypody

Materials ◽

10.3390/ma14112951 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2951

Author(s):

Mirosław Kwiatkowski ◽

Jarosław Serafin ◽

Andy M. Booth ◽

Beata Michalkiewicz

Keyword(s):

Activated Carbon ◽

Porous Structure ◽

Computer Analysis ◽

Density Functional ◽

Activated Carbons ◽

Chemical Activation ◽

Geometrical Parameters ◽

Activation Process ◽

Microporous Structure ◽

Activation Temperature

This paper presents the results of a computer analysis of the effect of activation process temperature on the development of the microporous structure of activated carbon derived from the leaves of common polypody (Polypodium vulgare) via chemical activation with phosphoric acid (H3PO4) at activation temperatures of 700, 800, and 900 °C. An unconventional approach to porous structure analysis, using the new numerical clustering-based adsorption analysis (LBET) method together with the implemented unique gas state equation, was used in this study. The LBET method is based on unique mathematical models that take into account, in addition to surface heterogeneity, the possibility of molecule clusters branching and the geometric and energy limitations of adsorbate cluster formation. It enabled us to determine a set of parameters comprehensively and reliably describing the porous structure of carbon material on the basis of the determined adsorption isotherm. Porous structure analyses using the LBET method were based on nitrogen (N2), carbon dioxide (CO2), and methane (CH4) adsorption isotherms determined for individual activated carbon. The analyses carried out showed the highest CO2 adsorption capacity for activated carbon obtained was at an activation temperature of 900 °C, a value only slightly higher than that obtained for activated carbon prepared at 700 °C, but the values of geometrical parameters determined for these activated carbons showed significant differences. The results of the analyses obtained with the LBET method were also compared with the results of iodine number analysis and the results obtained with the Brunauer–Emmett–Teller (BET), Dubinin–Radushkevich (DR), and quenched solid density functional theory (QSDFT) methods, demonstrating their complementarity.

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An Evaluation of the Impact of the Amount of Potassium Hydroxide on the Porous Structure Development of Activated Carbons

Materials ◽

10.3390/ma14082045 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2045

Author(s):

Mirosław Kwiatkowski ◽

Elżbieta Broniek ◽

Vanessa Fierro ◽

Alain Celzard

Keyword(s):

Density Functional Theory ◽

Porous Structure ◽

Potassium Hydroxide ◽

Density Functional ◽

Activated Carbons ◽

Chemical Activation ◽

Appropriate Technology ◽

Functional Theory ◽

Homogeneous Surface ◽

The Impact

This paper presents the results of an evaluation of the impact of the amount of potassium hydroxide on the obtained porous structure of the activated carbons derived from the shells of pistachios, hazelnuts, and pecans by carbonization and subsequent chemical activation with potassium hydroxide by different adsorption methods: Brunauer–Emmett–Teller, Dubinin–Raduskevich, the new numerical clustering-based adsorption analysis, Quenched Solid Density Functional Theory, and 2D-Non-linear Density Functional Theory for Heterogeneous Surfaces, applied to nitrogen adsorption isotherms at −196 °C. Based on the conducted research, a significant potential for the production of activated carbons from waste materials, such as nut shells, has been demonstrated. All the activated carbons obtained in the present study at the activator/char mass ratio R = 4 exhibited the most developed porous structure, and thus very good adsorption properties. However, activated carbons obtained from pecan shells deserve special attention, as they were characterized by the most homogeneous surface among all the samples analyzed, i.e., by a very desirable feature in most adsorption processes. The paper demonstrates the necessity of using different methods to analyze the porous structure of activated carbons in order to obtain a complete picture of the studied texture. This is because only a full spectrum of information allows for correctly selecting the appropriate technology and conditions for the production of activated carbons dedicated to specific industrial applications. As shown in this work, relying only on the simplest methods of adsorption isotherm analysis can lead to erroneous conclusions due to lack of complete information on the analyzed porous structure. This work thus also explains how and why the usual characterizations of the porous structure of activated carbons derived from lignocellulosic biomass should not be taken at face value. On the contrary, it is advisable to cross reference several models to get a precise idea of the adsorbent properties of these materials, and therefore to propose the most suitable production technology, as well as the conditions of the preparation process.

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In-situ NiO nanostructure growth during heating in water vapor atmosphere

Microscopy and Microanalysis ◽

10.1017/s1431927621007595 ◽

2021 ◽

Vol 27 (S1) ◽

pp. 2102-2103

Author(s):

Boyi Qu ◽

Klaus van Benthem

Keyword(s):

Water Vapor ◽

Water Vapor Atmosphere

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Oxidation Behavior of Maraging 300 Alloy Exposed to Nitrogen/Water Vapor Atmosphere at 500 °C

Metals ◽

10.3390/met11071021 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1021

Author(s):

Mauro Andres Cerra Florez ◽

Gemma Fargas Ribas ◽

Jorge Luiz Cardoso ◽

Antonio Manuel Mateo García ◽

Joan Josep Roa Rovira ◽

...

Keyword(s):

Water Vapor ◽

Oxide Layer ◽

Magnetic Layer ◽

Adhesive Force ◽

Point Of View ◽

Maraging Steels ◽

Cobalt Spinel ◽

Water Vapor Atmosphere ◽

Iron Nickel ◽

Ferrite Cobalt

Aging heat treatments in maraging steels are fundamental to achieve the excellent mechanical properties required in several industries, i.e., nuclear, automotive, etc. In this research, samples of maraging 300 alloy were aged using a novel procedure that combines different steps with two atmospheres (nitrogen and water vapor) for several hours. The oxidized surface layer was chemical, microstructural and micromechanically characterized. Due to the thermodynamic and kinetic conditions, these gases reacted and change the surface chemistry of this steel producing a thin iron-based oxide layer of a homogeneous thickness of around 500 nm. Within the aforementioned information, porosity and other microstructural defects showed a non-homogeneous oxide, mainly constituted by magnetite, nickel ferrite, cobalt ferrite, and a small amount of hematite in the more external parts of the oxide layer. In this sense, from a chemical point of view, the heat treatment under specific atmosphere allows to induce a thin magnetic layer in a mixture of iron, nickel, and cobalt spinel ferrites. On the other hand, the oxide layer presents an adhesive force 99 mN value that shows the capability for being used for tribological applications under sliding contact tests.

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Analysis of the Effect of Conditions of Preparation of Nitrogen-Doped Activated Carbons Derived from Lotus Leaves by Activation with Sodium Amide on the Formation of Their Porous Structure

Materials ◽

10.3390/ma14061540 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1540

Author(s):

Mirosław Kwiatkowski ◽

Xin Hu

Keyword(s):

Porous Structure ◽

Activated Carbons ◽

Structure Parameters ◽

Mass Ratio ◽

Nitrogen Doped ◽

Adsorption Analysis ◽

Lotus Leaves ◽

The Impact ◽

Sodium Amide ◽

Numerical Clustering

This paper presents results of the analysis of the impact of activation temperature and mass ratio of activator to carbonized precursor R on the porous structure of nitrogen-doped activated carbons derived from lotus leaves by carbonization and chemical activation with sodium amide NaNH2. The analyses were carried out via the new numerical clustering-based adsorption analysis (LBET) method applied to nitrogen adsorption isotherms at −195.8 °C. On the basis of the results obtained it was shown that the amount of activator, as compared to activation temperatures, has a significantly greater influence on the formation of the porous structure of activated carbons. As shown in the study, the optimum values of the porous structure parameters are obtained for a mass ratio of R = 2. At a mass ratio of R = 3, a significant decrease in the values of the porous structure parameters was observed, indicating uncontrolled wall firing between adjacent micropores. The conducted analyses confirmed the validity of the new numerical clustering-based adsorption analysis (LBET) method, as it turned out that nitrogen-doped activated carbons prepared from lotus leaves are characterized by a high share of micropores and a significant degree of surface heterogeneity in most of the samples studied, which may, to some extent, undermine the reliability of the results obtained using classical methods of structure analysis that assume only a homogeneous pore structure.

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Computer Analysis of the Porous Structure of Activated Carbons Derived from Various Biomass Materials by Chemical Activation

Materials ◽

10.3390/ma14154121 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4121

Author(s):

Mirosław Kwiatkowski ◽

Elżbieta Broniek

Keyword(s):

Porous Structure ◽

Adsorption Isotherms ◽

Computer Analysis ◽

Activated Carbons ◽

Chemical Activation ◽

Adsorbed Layer ◽

Dry Mass ◽

Mass Ratio ◽

Adsorption Volume ◽

Homogeneous Surface

In this study, the preparation of activated carbons from various materials of biomass origin by activation with potassium hydroxide and a comprehensive computer analysis of their porous structure and adsorption properties based on benzene (C6H6) adsorption isotherms were carried out. In particular, the influence of the mass ratio of the activator’s dry mass to the char mass on the formation of the microporous structure of the obtained activated carbons was analysed. The summary of the analyses carried out based on benzene adsorption isotherms begged the conclusion that activated carbon with a maximum adsorption volume in the first adsorbed layer and homogeneous surface can be obtained from ebony wood at a mass ratio of the activator to the char of R = 3. The obtained results confirmed the superiority of the new numerical-clustering-based adsorption analysis (LBET) method over simple methods of porous structure analysis, such as the Brunauer–Emmett–Teller (BET) and Dubinin–Raduskevich (DR) methods. The LBET method is particularly useful in the evaluation of the influence of the methods and conditions of production of activated carbons on the formation of their porous structure. This method, together with an appropriate economic analysis, can help in the precise selection of methods and conditions for the process of obtaining activated carbons at specific manufacturing costs, and thus makes it possible to obtain materials that can successfully compete with those of other technologies used in industrial practice and everyday life.

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