Thermogravimetric and textural studies of modified carbonaceous materials

Wachowski, L.; Hofman, Magdalena

doi:10.1016/j.tca.2005.06.018

Cited by 18 publications

(15 citation statements)

References 13 publications

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“…The material with the highest degree of coalification contains the greatest amount of carbon and the smallest amount of total oxygen and sulfur, being the components of volatile substances typical of the materials of organic origin [9][10]. As evidenced earlier, the procedure of nitrogen enrichment leads to considerable changes in the contents and proportions of particular elements [9][10][11]. The greatest amount of nitrogen was introduced to a sample of brown coal as a result of ammoxidation accompanied by the removal of the organic materials leading to a reduction in the amount of oxygen and sulfur.…”

Section: Resultsmentioning

confidence: 99%

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Catalytic activity of Pd/CN systems in hydrogenation of styrene

Hofman

Wachowski

2007

React Kinet Catal Lett

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Hydrogenation of styrene was applied as a test reaction to study the catalytic activity of Pd deposited on the surface of carbonaceous materials enriched with nitrogen (C N ). The nitrogen content in the support material was found to have a great influence on the degree of styrene conversion to ethylbenzene. In addition, the reaction was carried out in the presence of modified carbonaceous materials acting as catalysts.

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Section: Resultsmentioning

confidence: 99%

“…Ammoxidation (introducing of nitrogen into the carbonaceous materials structure) and carbonization were carried out according to procedures described in detail in [9][10][11][12]. Activation by steam was conducted at 1073 K for 1.5 h. Chemical composition of the samples investigated was established on an Elemental Vario ELIII microanalyzer.…”

Section: Methodsmentioning

confidence: 99%

Catalytic activity of Pd/CN systems in hydrogenation of styrene

Hofman

Wachowski

2007

React Kinet Catal Lett

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“…ammonia [22,23], urea [24,25], nitrogen oxides [26], hydroxyl amine and hydrazine [27], (2) pyrolysis/activation (mainly physical) of polymers or rich in nitrogen vegetation origin precursors (e.g. polyacrylonitrile [28], polyamides [29], polyimides [30] and waste material left after soybean growing and processing [31]; and (3) impregnation of carbons with solutions of amines and imines of any order [32,33] or coating carbons with a layer of polymers containing nitrogen in their structure [34].…”

Section: Introductionmentioning

confidence: 99%

Effect of heat treatment on the physicochemical properties of nitrogen-enriched activated carbons

Nowicki

2016

J Therm Anal Calorim

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A series of functionalized carbonaceous adsorbents were prepared by means of reaction with urea and chemical activation of Polish brown coal. In order to obtain nitrogen groups bonded in different ways to the carbon structure, the reaction with urea was performed at two different stages of processing, with precursor or char. Additionally, the influence of annealing under nitrogen atmosphere at 600 and 800°C or in hydrogen/nitrogen mixture at 600°C on the textural, acid-base and thermal properties of activated carbons prepared was tested. The resulting materials were characterized by elemental analysis, low-temperature nitrogen sorption, determination of the number of surface oxygen groups as well as by thermogravimetric study in helium atmosphere. The final products were microporous nitrogen-enriched activated carbons of very well-developed surface area reaching from 1303 to 2004 m 2 g -1 , showing different content of nitrogen (from 0.5 to 2.3 mass%) and different chemical character of the surface (from weakly acidic to intermediate acidic-basic), depending on the sequence of particular processes and variant of further thermochemical treatment. According to the results of thermal study, the nitrogen functional groups introduced into the carbon structure by the reaction with urea (especially at the char stage) show moderate thermal and chemical stability. Under the effect of high temperature, some of these groups underwent decomposition or transformation into more thermally stable nitrogen species. It was also proved that the thermochemical treatment of modified activated carbons led to considerable deterioration of their textural parameters as well as caused significant changes in the acid-base character of their surface.

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“…A recent study on the development of new catalysts, catalyst support materials _____________________________ and electrode materials [2], as well as competitive adsorbents [3] have indicated the possibilities of carbonaceous materials modified by the incorporation of nitrogen (C N ) [2,4,5]. Recently, a growing interest in nitrogen functionalities in carbonaceous materials is observed due to their interesting textural properties and high density of surface nitrogen sites of Lewis basic character [1,3].…”

Section: Introductionmentioning

confidence: 99%

“…The type of nitrogen functional groups present on the surface of carbonaceous materials determines also its anion and cation exchange properties [1,3]. It has been established earlier that the efficient method of enrichment in nitrogen is ammoxidation, involving a simultaneous oxidation of the precursor [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%