Synthesis and characterization of various MgO and related systems

Aramendía, M. A.; Boráu, V.; Jiménez, César; Marinas, J. M.; Porras, A.; Urbano, Francisco J.

doi:10.1039/jm9960601943

Cited by 63 publications

(70 citation statements)

References 26 publications

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“…Hydrotalcite formation may also serve as a means of heavy metal removal from heavy metal contaminated waters [12]. These hydrotalcites are readily synthesised by a co-precipitation method [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Thermogravimetric analysis of hydrotalcites based on the takovite formula NixZn6-xAl2(OH)16(CO3)·4H2O

Lin

Adebajo

Frost

et al. 2005

J Therm Anal Calorim

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High resolution thermogravimetric analysis (HRTG) coupled to a gas evolution mass spectrometer has been used to study the thermal decomposition of zinc-modified hydrotalcites of takovite formulation (Ni x Zn 6-x Al 2 (CO 3 )(OH) 16 .4H 2 O) where x varies from 0 to 6. X-ray diffraction data indicate an increase in the crystallinity and decrease in the interlayer spacing of the materials with increase in the zinc composition. The results of HRTG and mass spectrometry (MS) indicate that water is lost in two major steps at 90-150 and 160-300 °C, with carbon dioxide coming off simultaneously at the second step at 200-300 °C. Further loss of CO 2 was also observed at about 550-560 °C and 735-765 °C due to decomposition of carbonate chemically bound to layer Zn 2+ and Al 3+ cations, respectively. These two steps are attributed to dehydration and dehydroxylation/decarbonation, respectively. The temperature of dehydration was found to increase linearly with increase in the moles of zinc in the takovite formula. In contrast, the temperature of dehydroxylation/decarbonation decreases almost linearly with increase in zinc composition from Ni 5 Zn 1 hydrotalcite. These observations are discussed in terms of the effects of stabilisation of the layer structure, the electronegativity of the layer metals, the charge-to-size ratio of the layer cations and the layer-interlayer hydrogen bonding interactions. Chemical reactions are proposed for the decomposition of the synthesised takovite and zinc-substituted hydrotalcites.

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Section: Introductionmentioning

confidence: 99%

Thermogravimetric analysis of hydrotalcites based on the takovite formula NixZn6-xAl2(OH)16(CO3)·4H2O

Lin

Adebajo

Frost

et al. 2005

J Therm Anal Calorim

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“…Estas podem ser dividas em dois conjuntos, um em que a temperatura de calcinação utilizada foi tomada da literatura [7,9] e outro em que a mesma foi determinada a partir dos dados obtidos da curva TG.…”

Section: Determinação Da Temperatura De Calcinação Dos Precursoresunclassified

“…Entre 300 e 400 °C temos a principal perda de massa para este composto, da ordem de 30%, o que pode ser atribuído à liberação de uma molécula de água e formação do óxido de magnésio, suposição coerente com o cálculo estequiométrico e com os dados da literatura [9]. Com base nesta curva TG tomou-se como temperatura de calcinação a de 420 °C para a obtenção do MgO a partir do Mg(OH) 2 , portanto inferior aos 600 °C sugeridos na literatura.…”

Section: Determinação Da Temperatura De Calcinação Dos Precursoresunclassified

Síntese de éster de cadeia longa via catálise básica heterogênea

2009

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A long chain ester was prepared by transesterification of methyl palmitate with long chain alcohol using magnesium oxide as catalyst prepared by thermal decomposition of different precursors with the intention of establish relations among structural properties and activities. Temperature and catalyst amounts were modified in order to evaluate the yield of the ester in function the precursors used in preparation of the oxide.

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“…To avoid the surface basicity, there are several routes reported for obtaining magnesium oxides. One of the possible routes is the thermal decomposition of precursors [11][12][13] , and another is the sol-gel method 14 . Originally, magnesium oxide was rarely used as support for metal catalysts due to the problem of its low specific area.…”

Section: Introductionmentioning

confidence: 99%

Effect of the synthetic method of Pt/MgO in the hydrosilylation of phenylacetylene

Ramírez‐Oliva¹,

Hernández

Martínez-Rosales³

et al. 2006

Arkivoc

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This work describes the synthesis and characterization of Pt/MgO (Pt/Mg(OH) 2 , calcined Pt/MgO and agglomerated Pt/MgO ) catalysts. The supports of the catalysts were obtained by the hydrolysis-precipitation method and the metallic phase of platinum was incorporated by impregnation. The characterization of the synthesized materials was made by means of DRX, FTIR, TGA-DTA and TPR techniques. The catalysts were applied to the hydrosilylation of PhC≡CH with three different silanes (Ph 3 SiH, Ph 2 MeSiH and PhMe 2 SiH) as a model reaction. The activity of the proposed catalysts Pt/Mg(OH) 2 , calcined Pt/MgO and agglomerated Pt/MgO had a reaction yield of 95 %. When the catalysts Pt/Mg(OH) 2 and agglomerated Pt/MgO were used in the reaction with Ph 3 SiH, the selectivity to the trans isomer was favored (90%). A relationship was found between the increase in the reaction time and the increase of the kinetic volume of the silane radicals. The present results were compared to the previously obtained results using as a catalyst Pt/MgO obtained by the sol-gel method.

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Synthesis and characterization of various MgO and related systems

Cited by 63 publications

References 26 publications

Thermogravimetric analysis of hydrotalcites based on the takovite formula NixZn6-xAl2(OH)16(CO3)·4H2O

Thermogravimetric analysis of hydrotalcites based on the takovite formula NixZn6-xAl2(OH)16(CO3)·4H2O

Síntese de éster de cadeia longa via catálise básica heterogênea

Effect of the synthetic method of Pt/MgO in the hydrosilylation of phenylacetylene

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