CC BY
18DOI: 10.6060/tcct.20165912.5495
Для цитирования:
Жучко E.C., Румянцев Р.Н., Ильин А.А., Петухова К.А., Волкова А.В., Ильин А.П. Твердофазный синтез феррита кальция со структурой браунмиллерита. Изв. вузов. Химия и хим. технология. 2016. Т. 59. Вып. 12. С. 45-48. For citation:
Zhuchko E.S., Rumyantsev R.N., Il'in A.A., Petukhova K.A., Volkova A.V., Il'in A.P. Solid-phase synthesis of calcium ferrite with brownmillerite structure. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2016. V. 59. N 12. P. 45-48.
УДК: 666.32/36:666-492.2: 54-44 Е.С. Жучко, Р.Н. Румянцев, А.А. Ильин, К.А. Петухова, А.В. Волкова, А.П. Ильин
Екатерина Сергеевна Жучко
Университет Эдинбурга, Шотландия, 29 Buccleuch Place, EH8 9JS E-mail: [email protected]
Руслан Николаевич Румянцев (ЕЗ), Александр Александрович Ильин, Анжелика Викторовна Волкова, Ксения Андреевна Петухова, Александр Павлович Ильин
Кафедра технологии неорганических веществ, Ивановский государственный химико-технологический университет, просп. Шереметевский, 7, Иваново, Российская Федерация, 153000 E-mail: [email protected] (Н), [email protected], [email protected], [email protected], [email protected]
ТВЕРДОФАЗНЫЙ СИНТЕЗ ФЕРРИТА КАЛЬЦИЯ СО СТРУКТУРОЙ БРАУНМИЛЛЕРИТА
В работе с помощью методов рентгенофазового, рентгеноструктурного и синхронного термического анализа, а также сканирующей электронной микроскопии исследован процесс получения феррита кальция из оксалата железа(П) и гидроксида кальция при их твердофазном взаимодействии. Результаты рентгенофазового анализа образца, подвергнутого термической обработке при 750 °С в течение 3 ч, свидетельствуют об образовании однофазного феррита кальция со структурой браунмиллерита. Анализ кривых DTA, указывает на то, что процессы кристаллизации продолжаются до температуры >1000 °С. Расчет субструктурных параметров полученного Са2Ге20б показывает, что величина размера области когерентного рассеяния равна 198 А, а суммарное число микродеформаций составляет 0,8%. Площадь поверхности образца не превышает 5 м2/г.
Ключевые слова: феррит кальция, твердофазный синтез, условия получения
UDC: 666.32/36:666-492.2: 54-44 E.S. Zhuchko, R.N. Rumyantsev, A.A. Il'in, K.A. Petukhova, A.V. Volkova, A.P. Il'in
Ekaterina S. Zhuchko
University of Edinburgh, Scotland, 29, Buccleuch Place, EH8 9JS E-mail: [email protected]
Ruslan R. Rumyantsev (M), Aleksandr A. Il'in, Anzhelika V. Volkova, Kseniya A. Petukhova, Aleksandr P. Il'in
Inorganic Substances Technology Department, Ivanovo State University of Chemistry and Technology, Shere-metievskiy ave., 7, Ivanovo, 153000, Russia
E-mail: [email protected] (H), [email protected], [email protected], [email protected], [email protected]
SOLID-PHASE SYNTHESIS OF CALCIUM FERRITE WITH BROWNMILLERITE STRUCTURE
The process of calcium ferrite preparing from ferrum (II) oxalate and calcium hydroxide by solid-phase interaction was studied using data of X-ray diffraction, X-ray phase analysis, simultaneous thermal analysis, and scanning electron microscopy. X-ray phase analysis results of a sample subjected to heat treatment at 750 °C for 3 h, show formation of single-phase brownmil-lerite structure of calcium ferrite Ca2Fe2Os. Analysis of the DTA shows that crystallization process continues up to 1000 °C. Calculation of substructure parameters of Ca2Fe2Os shows that the area of coherent X-ray scattering is 198 A, total amount of microstrains is 0.8 %. The specific surface area of the sample is not more 5 m2/g.
Key words: calcium ferrite, solid phase synthesis, brownmillerite structure
Calcium ferrite possesses catalytic properties in a number of different reactions and can be used as analogue of precious metals containing catalyst [1, 2]. In [3, 4] it was proposed to use massive catalyst containing calcium and copper ferrites for carrying out a carbon monoxide conversion to hydrogen by steam, and properties of the catalyst was not inferior to traditional Fe-Cr oxide catalysts. The article [5] established the correlation between the maximum density of interfacial and the grain boundaries, the presence of weakly bounded oxygen and the specific catalytic activity of the samples in the reaction of CO oxidation. The authors of [6] examined the possibility of neutralization of gas emissions containing nitrogen oxide (I) on different crystal structures of ferrite catalysts.
Analysis of published data on the manufacture of calcium ferrite shows that there are different methods: precipitation from solution, the sol-gel, ceramic, mechanochemical and others [2, 5, 7-9]. It is known that producing method has a significant effect on the properties of the finished product. For example, specific surface area, content of acid-base centers and porosity have influence on the catalytic properties. Thus, to obtain materials with predetermined
properties, it is necessary to establish the correlation between the preparing conditions and catalyst's physico-chemical characteristics.
EXPERIMENTAL
Ferrum oxalate FeC2O4-2H2O and calcium hydroxide Ca(OH)2 were used for solid phase synthesis of calcium ferrite Ca2Fe2O5.
X-ray phase analysis (XRD) was performed on a diffractometer DRON-3M using Cu Ka radiation.
Substructure parameters were determined using Harmonic analysis of form the X-ray line (GIRL).
Thermogravimetric analysis (TG) and Differential thermal analysis (DTA) were performed using simultaneous thermal analysis instrument STA 449 F3 Jupiter at a heating rate of 5 °Cmin-1.
Microscopic images were obtained with a scanning electron microscope (SEM) VEGA 3 TESCAN.
The specific surface area was determined by the BET method using Sorbi-MS.
RESULTS AND ITS DISCUSSION
Figure 1 shows the results of simultaneous thermal analysis of a mixture of ferrum oxalate and
46
Изв. вузов. Химия и хим. технология. 2016. Т. 59. Вып. 12
calcium hydroxide in stoichiometric ratio to form calcium ferrite.
Т, °С
Fig. 1. Simultaneous thermal analysis of FeC2O4-2H2O and Ca(OH)2 mixture: 1-TG; 2- DTA Рис. 1. Результаты синхронного термического анализа 1-TG,
2- DTA
Fig. 2. The SEM images of Ca2Fe2Ü5 Рис. 2. СЭМ изображения Ca2Fe2Ü5
Calcination process is accompanied by 6 thermal effects (Fig.1):
I - endothermic heat effect at 130-200 °C -removal of adsorbed air and crystallization water;
ЛИТЕРАТУРА
1. Tejuca L.G., Fierro J.L.G., Tascon J.M.D. Structure and Reactivity of Perovskite-Type Oxides. Advances in catalysis. 1989. V. 36. С. 328-237.
2. Исупова Л.А., Цыбуля С.В. Крюкова Г.Н. Механохи-мический синтез и каталитические свойства феррита кальция Са2Fе2O5. Кинетика и катализ. 2002. Т. 43. № 1. С. 132-139.
II - exothermic heat effect at 200-285 °C -carbon monoxide oxidation, which is formed by the decomposition of ferrum oxalate;
III - exothermic heat effect at 360-380 °C can be caused by polymorphic transition of y-Fe2O3 formed according to reaction (1) into a-Fe203;
t, 0.5 Q3
2FeC204 2H20-> y-Fe203 + 2CO +
+2C02 + 4H20 (1)
IV - endothermic heat effect at 380-410 °C -calcium hydroxide decomposition.
V - endothermic heat effect at 650-680 °C-calcium carbonate decomposition (which is due to calcium hydroxide carbonization during mechanical mixing of the initial reagents);
VI - exothermic heat effect is greatly extended and shows Ca2Fe2O5 crystallization.
X-ray analysis of the sample calcined at 750 °C shows that the structure is one-phase. A set of reflections on the X-ray pattern corresponds to the brownmillerite structure of the calcium ferrite.
SEM images (Fig. 2) shows that it consists of spherical particles 0,1-0,2 size of microns, which form conglomerates of larger size (2-10 ^m).
Table shows the conditions of the reaction and Ca2Fe2O5 characteristics.
Table.
Reaction conditions and Ca2Fe2O5 characteristics Таблица. Условия получения и характеристики Ca2Fe2O5
Formula Calcining temperature, °С Calcining time, hour Specific surface, m2/g Coherent X-ray scattering, A Total amount of microstrains, %
Ca2Fe2Ü5 750 3 5 198 0,8
Acknowledgements
This work was supported by the Russian President's scholarship for young scientists and graduate students engaged in advanced research and development in priority areas of modernization of the Russian economy (2016-2018) №SP-3477.2016.1.
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Поступила в редакцию 26.09.2016 Принята к опубликованию 28.11.2016
Received 26.09.2016 Accepted 28.11.2016
. вузов. Химия и хим. технология. 2016. Т. 59. Вып. 12
