Preparation and thermal properties of commercial vermiculite bonded with potassium silicate

Petersen, Rasmus Rosenlund; Christensen, Johan Frederik Schou; Jørgensen, Niels Terp Kjeldgaard; Gustafson, S.; Lindbjerg, L.A.; Yue, Yuanzheng

doi:10.1016/j.tca.2021.178926

Cited by 14 publications

(9 citation statements)

References 30 publications

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“…However, the activity and reusability of Mt-based catalyst was unsatisfactory for cellulose hydrolysis in water [ 13 ]. Among clay minerals, vermiculite (Vrm) is also the 2:1 type phyllosilicate, which is widely used in construction, agriculture and horticulture, metallurgical industry, animal husbandry, etc., [ 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. In fact, although Vrm is in the same group of the smectites as Mt, Vrm has unique structure characteristics [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Acid Leaching Vermiculite: A Multi-Functional Solid Catalyst with a Strongly Electrostatic Field and Brönsted Acid for Depolymerization of Cellulose in Water

et al. 2022

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Vermiculite is a natural mineral. In this study, vermiculite and acid-activated vermiculite was used as a solid acid catalyst for the hydrolysis of cellulose in water. The catalysts were characterized by XRD, FT-IR, and BET. The effects of time, temperature, mass ratio and water amount on the reaction were investigated in the batch reactor. The results showed that the highest total reducing sugars (TRS) yield of 40.1% could be obtained on the vermiculite activated by 35 (wt)% H2SO4 with the mass ratio of catalyst to cellulose of 0.18 and water to cellulose of 16 at 478 K for 3.5 h. The acid-activated vermiculite was a stable catalyst through calcination at 628 K and the yield of TRS decreased to 36.2% after three times reuse. The results showed that the crystal structure of vermiculite was destroyed and the surface -OH groups increased after the acid treatment. However, the synergistic effect of a strongly electrostatic polarization and Brönsted acid was responsible for the efficient conversion of cellulose. The mechanism of cellulose hydrolysis on the acid-activated vermiculite was suggested. This work provides a promising strategy to design an efficient solid catalyst for the cellulose hydrolysis, and expands the use of vermiculite in a new field.

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Section: Introductionmentioning

confidence: 99%

Acid Leaching Vermiculite: A Multi-Functional Solid Catalyst with a Strongly Electrostatic Field and Brönsted Acid for Depolymerization of Cellulose in Water

et al. 2022

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“…However, the activity and reusability of Mt based catalyst was unsatisfactory for cellulose hydrolysis in water [13]. Among clay minerals, vermiculite (Vrm) is also the 2:1 type phyllosilicate, which is widely used in construction, agriculture and horticulture, metallurgical industry, animal husbandry, etc [14][15][16][17][18][19][20]. In fact, although Vrm is in the same group of the smectites with Mt, Vrm has the unique structure characteristics [21].…”

Section: Introductionmentioning

confidence: 99%

Acid leaching vermiculite: A multi-functional solid catalyst with strongly electrostatic field and Brönsted acid for depolymerization of cellulose in water

Chen

Tong

Fang

et al. 2022

Preprint

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Vermiculite is a natural, environmentally friendly mineral, which is widely used in construction, thermal insulation, metallurgy, and agriculture. In this study, vermiculite and acid-activated vermiculite was used as a solid acid catalyst for the hydrolysis of cellulose in water. The vermiculite based solids were characterized by XRD, FT-IR, and BET. The effects of reaction time, reaction temperature, mass ratio and water amount on the reaction were also investigated in the batch reactor. The results showed that the highest total reducing sugars (TRS) yield of 40.1% could be obtained on the vermiculite activated by 35(wt)% H2SO4 with the mass ratio of catalyst to cellulose of 0.18 and water to cellulose of 16 at 478 K for 3.5 h. The acid-activated vermiculite was also a stable catalyst through calcination at 628 K and the yield of TRS decreased from 40.1% to 36.2% after three times reuse. The results showed that the crystal structure of vermiculite was almost destroyed and the surface -OH groups increased after the acid treatment. However, the synergistic effect of strongly electrostatic polarization and Brönsted acid was responsible for the efficient conversion of cellulose. Finally, the mechanism of cellulose hydrolysis on the acid-activated vermiculite was suggested. This work provides a promising strategy to design an efficient solid catalyst for the cellulose hydrolysis, and also expands the use of vermiculite in a new field.

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“…Intumescent property of alkali silicates has garnered extensive research and industrial attraction over the last decades, particularly, due to their thermal insulation properties at high temperature-a source of fire-protection 1,2 in several construction materials including fire-resistant glass windows. Furthermore, the ability of such silicate materials to act as strong binders in coatings [3][4][5] and to improve the bonding properties in geopolymers [6][7][8] makes them potential candidates for a low-cost, stable, and green alternative to several organic systems. Their foaming behavior in fire-protective systems has been the subject of numerous investigations especially when these silicates are applied as coatings.…”

Section: Introductionmentioning

confidence: 99%

Crystallization‐induced suppression of intumescence in aqueous alkali silicates

et al. 2022

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Thermal properties of aqueous alkali silicates have been investigated to establish a fundamental understanding of the structural state of silicate network and its impact on intumescence, up to 450°C. Foaming behavior is dependent upon the type of alkali ion (Na, K, Li) as well as composition as evidenced from a combination of tools involving thermogravimetric analysis, nuclear magnetic resonance, and X‐ray diffraction. Na silicates show extensive foaming, Li‐silicates do not foam, whereas K‐silicates exhibit an intermediate behavior depending upon the starting state and heating kinetics. Crystallization is observed for K‐ and Li‐silicates but not in the case of Na‐silicates and appears to be a limiting factor for macroscopic structural expansion. Quantitative analysis of different species reveals the network to be relatively mobile, in terms of its ability to reorganize, in pre‐dried (at 150°C) Na‐silicates. A reduction in this mobility is seen for K‐silicates as crystallization reduces K ions and silanols in the amorphous phase at and above 150°C, thus reducing the extent of foaming. In contrast, phase separation coupled with crystallization resulting in a complete exit of Li ions from the amorphous phase tends to suppress completely the intumescent phenomenon.

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Preparation and thermal properties of commercial vermiculite bonded with potassium silicate

Cited by 14 publications

References 30 publications

Acid Leaching Vermiculite: A Multi-Functional Solid Catalyst with a Strongly Electrostatic Field and Brönsted Acid for Depolymerization of Cellulose in Water

Acid Leaching Vermiculite: A Multi-Functional Solid Catalyst with a Strongly Electrostatic Field and Brönsted Acid for Depolymerization of Cellulose in Water

Acid leaching vermiculite: A multi-functional solid catalyst with strongly electrostatic field and Brönsted acid for depolymerization of cellulose in water

Crystallization‐induced suppression of intumescence in aqueous alkali silicates

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