The basicity of mixed oxides and the influence of alkaline metals: The case of transesterification reactions

Fraile, José M.; García, Nuria; Mayoral, José A.; Pires, Elísabet; Roldán, Laura

doi:10.1016/j.apcata.2010.08.002

Cited by 45 publications

(26 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…One plausible explanation is related to the more effective mass transfer rate of reactants to the catalytic sites inside the geopolymer matrix, as Na-GP had a higher average pore size (17 nm) than K-GP (9 nm), as shown in Table 1 . Other aspects should also be further evaluated, including the differences in the basicity of the catalytic sites and the interference caused by metals from the geopolymers leaching into the reaction mixture [ 33 , 34 ]. Further work will also have to be carried out to quantify and compare the amount of gel formed in the Na- and K-geopolymers, as the catalytic performance might be affected by the degree and modality of the incorporation of the alkaline ions into the geopolymer network.…”

Section: Resultsmentioning

confidence: 99%

Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts

et al. 2020

View full text Add to dashboard Cite

This work investigates the catalytic activity of geopolymers produced using two different alkali components (sodium or potassium) and four treatment temperatures (110 to 700 °C) for the methyl transesterification of soybean oil. The geopolymers were prepared with metakaolin as an aluminosilicate source and alkaline activating solutions containing either sodium or potassium in the same molar oxide proportions. The potassium-based formulation displayed a higher specific surface area and lower average pore size (28.64–62.54 m²/g; 9 nm) than the sodium formulation (6.34–32.62 m²/g; 17 nm). The reduction in specific surface area (SSA) after the heat treatment was more severe for the sodium formulation due to the higher thermal shrinkage. The catalytic activity of the geopolymer powders was compared under the same reactional conditions (70–75 °C, 150% methanol excess, 4 h reaction) and same weight amounts (3% to oil). The differences in performance were attributed to the influences of sodium and potassium on the geopolymerization process and to the accessibility of the reactants to the catalytic sites. The Na-based geopolymers performed better, with FAME contents in the biodiesel phase of 85.1% and 89.9% for samples treated at 500 and 300 °C, respectively. These results are competitive in comparison with most heterogeneous base catalysts reported in the literature, considering the very mild conditions of temperature, excess methanol and catalyst amount and the short time spent in reactions.

show abstract

Section: Resultsmentioning

confidence: 99%

Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The strong basicity in mixed oxides is connected to the presence of alkaline metals. (Fraile et al, 2015). In Figures 7 and 8, dependence of the measured signal from the calcination temperature can be Navajasa et al, 2018).…”

Section: Temperature-programmed Desorption Of Co 2 (Tpd-co 2 )mentioning

confidence: 84%

Influence of hydrotalcite preparation conditions on its physico-chemical properties

Mališová

Horňáček

Hudec

et al. 2019

Acta Chimica Slovaca

View full text Add to dashboard Cite

The aim of the research was to prepare and characterize hydrotalcite synthesized under different preparation conditions. The most common hydrotalcite preparation is the co-precipiaton method. The preparation process strongly influences the catalytic properties of hydrotalcite; therefore, optimal conditions have to be determined. During the study, seven samples of the catalyst were prepared in the pH range from 8 to 12 and the synthesis temperature range from 25 to 55 °C. Based on several catalyst properties, optimal synthesis pH 10 was found. Ideal temperature of the preparation was determined to be 35 °C, but the temperature does not have a significant effect on the catalyst properties.

show abstract

“…33 The O 2À species has been reported to be the strong base site for solid base catalysts. 36,37 For the CeO 2 @CaO-60 catalyst, the O I to O II ratios is 0.86, which is highest among all the CaO-based catalysts, so it has the strongest basic strength. It is particularly noted that the CeO 2 had very low basicity due to the nature of the oxygen species of CeO 2 (ref.…”

Section: Catalysts Characterizationmentioning

confidence: 99%

The activity and stability of CeO₂@CaO catalysts for the production of biodiesel

Zhang

Xue

2018

RSC Adv.

View full text Add to dashboard Cite

show abstract

The basicity of mixed oxides and the influence of alkaline metals: The case of transesterification reactions

Cited by 45 publications

References 18 publications

Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts

Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts

Influence of hydrotalcite preparation conditions on its physico-chemical properties

The activity and stability of CeO₂@CaO catalysts for the production of biodiesel

Contact Info

Product

Resources

About

The basicity of mixed oxides and the influence of alkaline metals: The case of transesterification reactions

Cited by 45 publications

References 18 publications

Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts

Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts

Influence of hydrotalcite preparation conditions on its physico-chemical properties

The activity and stability of CeO2@CaO catalysts for the production of biodiesel

Contact Info

Product

Resources

About

The activity and stability of CeO₂@CaO catalysts for the production of biodiesel