Characterization of reaction products and reaction process of MgO–SiO2–H2O system at room temperature

Li, Zhaoheng; Zhang, Tongsheng; Hu, Jie; Tang, Yue; Niu, Yanfei; Wei, Jiangxiong; Yu, Qijun

doi:10.1016/j.conbuildmat.2014.03.004

Cited by 121 publications

(107 citation statements)

References 28 publications

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“…In particular, the ZrZn/MgO-SiO 2-1 system presented broad peaks (at 25-30 , 33-39 and 58-62) characteristic of magnesium silicate hydrates. [34,35] Since samples containing ZrO2 and ZnO have shown similar pXRD patterns compared to the initial MgO-SiO 2 support, ZrO2 and ZnO should be dispersed into the -Mg-OSi-network or their small loading was undetectable by pXRD. These results highlight the effect of preparation method on catalyst properties, since MgO phase was observed even for Mg:Si molar ratio equal to 1, using a solgel technique.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, samples presented a common amorphous structure with the three broad peaks (at 25-30 , 33-39 and 58-62) characteristic of magnesium silicate hydrates. [34,35] The local environment of the silicon atoms on the catalyst surface was investigated through 29 Si MAS NMR spectroscopy, Figure S17. Figure S17(a) shows spectra for catalysts i) MgO-SiO2-1, ii) ZrZn/MgO-SiO2-1, iii) 0.8-Na/ZrZn/MgO-SiO2-1, iv) 1.2-Na/ZrZn/MgO-SiO2-1 and v) 2-Na/ZrZn/MgO-SiO2-1.…”

Section: Catalyst Characterisationmentioning

confidence: 99%

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Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

et al. 2016

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Abstract:The conversion of ethanol to 1,3-butadiene (1,3-BD) has been investigated over ZrO2 and ZnO containing magnesia silica oxides prepared by co-precipitation method at different Mg-to-Si molar ratios. The effect of reaction temperature and ethanol flow rate was investigated. The catalyst acidity was modified through the addition of alkali metals (Na, K and Li) to the final materials. Catalysts were characterised by nitrogen physisorption analysis, Xray diffraction, scanning electron microscopy with energy dispersive X-ray, temperature programmed desorption of ammonia, infrared spectroscopy and 29 Si/( 7 Li) NMR spectroscopy. The catalytic results showed that the controlled reduction of catalyst acidity allows suppressing of ethanol dehydration, whilst increasing 1,3-BD selectivity. The best catalytic performance achieved 72 mol % for the combined 1,3-BD and acetaldehyde selectivity.

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Section: Resultsmentioning

confidence: 99%

Section: Catalyst Characterisationmentioning

confidence: 99%

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

et al. 2016

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“…The experimental measurements of pH and solution chemistry were compared as much as possible with predictions made using Visual MINTEQ 2.6 [11], a windows implementation of the MINTEQA2 algorithm [12] for calculation of geochemical aqueous equilibria, which uses the thermochemical data contained within [20]. Unfortunately no information was found for the interaction of sodium hexametaphosphate with magnesium.…”

Section: Thermodynamic Modelling Of the Solution Chemistrymentioning

confidence: 99%

“…The structure of M-S-H gel produced by reacting MgO and silica fume (SF) with water has recently been reported using x-ray diffraction, IR spectra, DTA-TGA-EGA and NMR studies [9][10][11]14].…”

Section: Introductionmentioning

confidence: 99%

Role of sodium hexametaphosphate in MgO/SiO2 cement pastes

Jia

Wang

et al. 2016

Cement and Concrete Research

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The extent of reaction between magnesium oxide (MgO) and silica fume (SiO2) is normally limited and mixes require high water contents to give suitable rheology. The use of considerably lower water contents and the formation of magnesium silicate hydrate (M-S-H) gel as a binding phase is made possible by adding sodium hexametaphosphate (Na-HMP) to the mix water prior to the addition of MgO and SiO2. This results in the formation of extensive reaction products and cured samples with high compressive strength and low porosity. In this work, the effect of Na-HMP on the hydration of MgO/SiO2 mixes is investigated using high water to solids ratio samples to allow monitoring of pH and the solution chemistry during hydration. It is shown that a relatively small amount of Na-HMP inhibits the formation of Mg(OH)2 when MgO is hydrolyzed. It is proposed that this is due to adsorption of phosphate species on the MgO which inhibits the nucleation of the Mg(OH)2.. This gives rise to high Mg 2+ species in solution and elevated pH (>12) conditions relative to when Mg(OH)2 forms. In contrast, the phosphate does not suppress formation of M-S-H gel. In combination with the enhanced dissolution rate of SiO2 at high pH, M-S-H gel can form quickly without competition for Mg 2+ ions by Mg(OH)2 precipitation. Incorporating the optimum concentration of Na-HMP into the mix water therefore transforms the properties of cement paste and mortar samples formed by reacting MgO and SiO2.

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“…Literature has indicated that the hydration products of MgO-SiO 2 -H 2 O system are primarily composed of Mg(OH) 2 and MSH gel, which is formed by the reaction of MgO and amorphous silica in the presence of sodium hexametaphosphate (Na-HMP) [1][2][3]. The properties of magnesium silicate hydrate cement have also been studied by some scholars [4,5].…”

Section: Introductionmentioning

confidence: 99%

Chloride Ion Penetration Resistance and Pore Structure of Magnesium Silicate Hydrate (M-S-H) Mortars

Zhang¹,

He²,

Wu³

et al. 2018

Proceedings of the 4th Annual International Conference on Material Engineering and Application (ICMEA 2017)

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Abstract-The main purpose of this paper is to study the chloride ion penetration resistance and pore structure of magnesium silicate hydrate cement (MSH) mortars. The chloride ion penetration resistance of MSH mortars with different water-to-cement ratios (0.5, 0.55, 0.6) and different sand rates (25%, 50%, 75%) was studied and compared to ordinary Portland cement (OPC) mortars. The pore structure of magnesium silicate hydrate mortar was tested using mercury intrusion porosimetry (MIP). The results indicate that the chloride ion diffusion coefficient becomes larger with an increase in the water-to-cement ratio and sand rate; the coefficient of MSH mortars is much smaller than that of OPC mortars. The results of MIP show that MSH mortars generally have gel pores measuring less than 10nm; however, the pore size of OPC mortars is dominated by pores measuring 10nm to 100nm. Finally, MSH mortars were found to be less porous than OPC mortars.

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Characterization of reaction products and reaction process of MgO–SiO2–H2O system at room temperature

Cited by 121 publications

References 28 publications

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Role of sodium hexametaphosphate in MgO/SiO2 cement pastes

Chloride Ion Penetration Resistance and Pore Structure of Magnesium Silicate Hydrate (M-S-H) Mortars

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Characterization of reaction products and reaction process of MgO–SiO2–H2O system at room temperature

Cited by 121 publications

References 28 publications

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO2 Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO2 Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Role of sodium hexametaphosphate in MgO/SiO2 cement pastes

Chloride Ion Penetration Resistance and Pore Structure of Magnesium Silicate Hydrate (M-S-H) Mortars

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Product

Resources

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Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification