Infrared Study of Carbon Dioxide Adsorbed on Magnesium and Calcium Oxides

Fukuda, Yasuo; Tanabe, Kozo

doi:10.1246/bcsj.46.1616

Cited by 143 publications

(100 citation statements)

References 11 publications

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“…Analogous to the surface hydroxyl groups formed on MgO in the presence of water vapor, whether some kinds of surface structure are formed on MgO by the adsorption of CO 2 . These surface structures resulted from the adsorption of CO 2 have been relatively well confirmed by several workers [15][16][17][18][19] using the infra-red study as shown in Figure 2. They used the active MgO as the raw material and the adsorption of CO 2 was carried out either at room temperature or at temperature varied from 473 K to 773 K. Four major vibrational frequencies for unidentate carbonates (Figure 2 .…”

Section: Introductionsupporting

confidence: 78%

“…In spectrum (4), the disappearing bands of CO 3 2− indicate that the amount of adsorbed CO 2 was reduced. According to Fukuda and Tanabe, 16 both unidentate and bidentate carbonates are formed on MgO when a small amount of CO 2 is adsorbed and unidentate carbonates predominate with the increasing amount of adsorbed CO 2 . So, the bidentate carbonates may be assigned to the third group.…”

mentioning

confidence: 99%

“…So, the bidentate carbonates may be assigned to the third group. On the other hand, several papers [15][16][17] attributed the bidentate carbonates to the bands at 850 cm −1 of infra-red spectrum. If the bidentate carbonates are both Raman active and infra-red active, this may provide another reason for the bidentate carbonates to be assigned to the bands at 850 cm , which appeared in spectrum (2) and disappeared in spectrum (3).…”

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confidence: 99%

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Study on the Kinetics and Mechanism of Grain Growth during the Thermal Decomposition of Magnesite

Fu¹,

Niu²,

Wang³

2012

Bulletin of the Korean Chemical Society

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The X-ray line broadening technique was used to calculate the grain size of MgO at 1023, 1123, 1223 K respectively either in CO 2 or during the thermal decomposition of magnesites in air as well as in vacuum. By referring to the conventional grain growth equation, D n = kt, the activation energy and pre-exponential factor for the process in air are gained as 125.8 kJ/mol and 1.56 × 10 8 nm 4/s, respectively. Ranman spectroscopy was employed to study the surface structure of MgO obtained during calcination of magnesite, by which the mechanism of grain growth was analyzed and discussed. It is suggested that a kind of highly reactive MgO is produced during the thermal decomposition of magnesites, which is exactly the reason why the activation energy of the grain growth during the thermal decomposition of magnesite is lower than that of bulk diffusion or surface diffusion.

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Section: Introductionsupporting

confidence: 78%

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confidence: 99%

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confidence: 99%

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Study on the Kinetics and Mechanism of Grain Growth during the Thermal Decomposition of Magnesite

Fu¹,

Niu²,

Wang³

2012

Bulletin of the Korean Chemical Society

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“…Peaks A, B, and C can be assigned to stretching modes of C─O bonds with intermediate strength as those involved in carbonates in ionic compounds. It has been well known for several decades that CO 2 can be adsorbed at ambient pressure on the surface of basic metal oxides and a variety of zeolites that contain transition, alkali, or alkaline earth metals (20)(21)(22)(23)(24)(25)(26)(27). The adsorption results in the formation of unidentate and bidentate carbonates (see Fig.…”

Section: Resultsmentioning

confidence: 99%

Silicon carbonate phase formed from carbon dioxide and silica under pressure

Santoro

Gorelli

Haines

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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The discovery of nonmolecular carbon dioxide under high-pressure conditions shows that there are remarkable analogies between this important substance and other group IV oxides. A natural and long-standing question is whether compounds between CO 2 and SiO 2 are possible. Under ambient conditions, CO 2 and SiO 2 are thermodynamically stable and do not react with each other. We show that reactions occur at high pressures indicating that silica can behave in a manner similar to ionic metal oxides that form carbonates at room pressure. A silicon carbonate phase was synthesized by reacting silicalite, a microporous SiO 2 zeolite, and molecular CO 2 that fills the pores, in diamond anvil cells at 18-26 GPa and 600-980 K; the compound was then temperature quenched. The material was characterized by Raman and IR spectroscopy, and synchrotron X-ray diffraction. The experiments reveal unique oxide chemistry at high pressures and the potential for synthesis of a class of previously uncharacterized materials. There are also potential implications for CO 2 segregation in planetary interiors and for CO 2 storage.high-pressure chemistry | material science | optical spectroscopy C arbon dioxide and silicon dioxide are two archetypal, group IV oxides of paramount importance for fundamental and applied chemistry and planetary sciences. CO 2 is the dominant component of the atmosphere of Earth-like planets, exists in icy forms in outer planets and asteroids, plays an important role in volcanic and seismic processes, is used as a supercritical solvent for chemical reactions, and its anthropogenic production is a major environmental issue. SiO 2 is also one of the most abundant components of terrestrial planets, and an important technological material. The chemical relationship between CO 2 and SiO 2 , in particular their reactivity, is thus of interest. Although the two systems are both group IV oxides, they are remarkably different under ambient conditions, because CO 2 is molecular and is held together by C═O double bonds, whereas SiO 2 forms network structures involving single Si─O bonds. These bonding patterns radically change under pressure. Two nonmolecular CO 2 crystalline phases and a glassy form have been discovered above 30 GPa that bear similarities to SiO 2 (1-14). The crystalline phases contain carbon in fourfold coordination by oxygen (1-10, 13, 14), and mixtures of CO 4 and CO 3 units have been found in a glassy form that has been named carbonia (13).A possible approach to favor the chemical reaction between CO 2 and SiO 2 is to select a microporous silica polymorph, such as silicalite. At ambient conditions, silicalite is characterized by a framework of four-, five-, six-, and ten-membered rings of SiO 4 tetrahedra with 5.5-Å pores (15) (Fig. 1, Left Inset). Recently, it has been found that the pores can be completely filled by simple molecules such as CO 2 and Ar under pressure, which prevents pressure-induced amorphization (PIA) and stabilizes the crystalline framework up to at least 25 GPa at room temperature (1...

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“…literatura 16,17 confirma sua presença no resíduo, em ambos os casos. Espectros IV dos resíduos e do CaO também poderiam ser obtidos pelos alunos.…”

Section: Figura 2 Espectros De Infravermelho De (A) Cao -Pa (B) Resunclassified

Termogravimetria: um novo enfoque para a clássica determinação de cálcio em cascas de ovos

Pereira¹,

Okumura²,

Ramos³

et al. 2009

Quím. Nova

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Recebido em 15/3/08; aceito em 5/2/09; publicado na web em 28/7/09 TERMOGRAVIMETRY: A NEW APPROACH FOR THE CLASSIC DETERMINATION OF CALCIUM IN EGGSHELLS. The use of thermoanalytical data in sample preparation is described as a tool to catch the students' attention to some details that can simplify both the analysis and the analytical procedure. In this case, the thermal decomposition of eggshells was first investigated by thermogravimetry (TGA). Although the classical procedures suggest long exposure to high temperatures, the TGA data showed that the decomposition of organic matter takes place immediately when the sample is heated up to 800 °C under air atmosphere. After decomposition, the calcium content was determined by flame atomic emission photometry and compared with the results obtained using classical volumetric titration with EDTA.Keywords: thermogravimetry; flame atomic emission photometry; sample preparation. INTRODUÇÃOA determinação de cálcio em cascas de ovos é um experimento clássico, frequentemente empregado no ensino de química analítica quantitativa e de análise instrumental. Há vários experimentos simples usando o carbonato de cálcio contido nessas cascas, para demonstrar princípios de ácidos e bases, entre outros. 1,2A principal função do carbonato na casca é conferir dureza e resistência mecânica, 3,4 podendo ser um parâmetro para definir condições da saúde do animal e um guia para controle de sua nutrição.Além disso, as cascas têm sido usadas como fonte de cálcio na alimentação de pessoas carentes. 5,6 Portanto, a determinação do teor de cálcio em cascas de ovos, não apresenta apenas aspectos didáticos e acadêmicos, sendo importante também na produção animal e até na nutrição humana.A análise térmica compreende um conjunto de técnicas que medem a variação em uma propriedade física de uma amostra submetida a uma programação controlada de temperatura, como foi definido por MacKenzie 1,7 e previamente discutido nesse periódico. 8,9 Dentre as técnicas de análise térmica mais usadas está a termogravimetria (TG), a qual acompanha a variação da propriedade física massa, enquanto a amostra é aquecida.A perda de massa pode ser relacionada com muitos fenômenos, como desidratação, sublimação, decomposição, entre outros, que podem servir para diferentes aplicações, resumidas por Ionashiro, 10 como: estudo de decomposição térmica de minerais, minérios, carvão, petróleo, madeira, polímeros, alimentos, materiais explosivos etc; estudos sobre corrosão de metais em atmosfera controlada, em faixas amplas de temperatura; estudos sobre a velocidade de evaporação de líquidos e sublimação de sólidos.Apesar da grande aplicabilidade, as técnicas de análise térmica nem sempre são apresentadas aos estudantes de graduação, pois dado o custo dos equipamentos, estes, geralmente, não estão disponíveis em laboratórios didáticos.Por outro lado, a fotometria de chama é a mais simples das téc-nicas analíticas baseadas em espectroscopia atômica. Nesse caso, a amostra contendo cátions metálicos é inserida por nebulização em u...

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Infrared Study of Carbon Dioxide Adsorbed on Magnesium and Calcium Oxides

Cited by 143 publications

References 11 publications

Study on the Kinetics and Mechanism of Grain Growth during the Thermal Decomposition of Magnesite

Study on the Kinetics and Mechanism of Grain Growth during the Thermal Decomposition of Magnesite

Silicon carbonate phase formed from carbon dioxide and silica under pressure

Termogravimetria: um novo enfoque para a clássica determinação de cálcio em cascas de ovos

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