Statistical evaluation of the mutual relations of properties of Mg/Fe hydrotalcites and mixed oxides as transesterification catalysts

Hájek, Martin; Tomášová, Adéla; Kocík, Jaroslav; Podzemná, Veronika

doi:10.1016/j.clay.2017.12.039

Cited by 17 publications

(15 citation statements)

References 31 publications

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“…It can be concluded that the samples with nominal molar ratio > 5 have relatively lower crystallinity compared to those with lower ratios. Indeed, the same experimental trend was shown in our previous study on a similar MgFe series where samples with Mg:Fe > 3 had lower crystallinity . It should be noted that, according to other studies, pure Mg/Al hydrotalcites without phase ad/mixtures are usually formed with molar ratios ranging from 2 to 4 .…”

Section: Resultssupporting

confidence: 88%

“…Indeed, the same experimental trend was shown in our previous study on a similar Mg-Fe series where samples with Mg:Fe > 3 had lower crystallinity. 25 It should be noted that, according to other studies, pure Mg/Al hydrotalcites without phase ad/mixtures are usually formed with molar ratios ranging from 2 to 4. 14,15,31 However, the XRD pattern of the second hydrotalcite phase in the present Mg-Fe series was not detected even for the highest studied ratio of Mg:Fe = 10.…”

Section: Physicochemical Characteristicsmentioning

confidence: 92%

“…11,14,22,23 Our work focused on hydrotalcite-based Mg-Fe mixed oxides, which we had successfully tested as basic catalysts for transesterification of rapeseed oil. 24,25 Mg-Fe mixed oxides also had been used by others in the transesterification of microalgal oil 26 and the etherification of glycerol. 27 Mg-Fe-Al oxides had been tested previously in ethanol condensation reaction.…”

Section: Introductionmentioning

confidence: 99%

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Pyroaurite‐based MgFe mixed oxides and their activity in aldol condensation of furfural with acetone: effect of oxide composition

Kocík

Frolich

Perková

et al. 2018

J of Chemical Tech & Biotech

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Background Pyroaurite‐based MgFe oxides with varying Mg:Fe ratio were studied. The structural and acido‐basic properties were examined by number of experimental techniques. The oxide properties were correlated with the catalytic activity in aldol condensation of furfural with acetone. Results Well‐developed mesoporous structure was detected for all oxides. Peculiar continuous increase of concentration of basic sites and population of unsaturated strong basic O2− sites was observed with the rising amount of magnesium in the MgFe oxide matrix. A relatively higher concentration of Lewis acid Men+ sites was shown for low Mg:Fe ratios. Unambiguous correlation between conversion of furfural and the density of strong basic sites was proved by combined catalytic and statistical analysis. The contribution of other basic sites was found significantly less important. The impact of both acid and basic sites on the composition of reaction products was discussed. Conclusions MgFe oxides revealed good catalytic performance in the aldol condensation of furfural with acetone where samples with a high Mg:Fe ratio were significantly more basic and had relatively enhanced furfural conversion (nominal Mg:Fe ratio 10; furfural conversion 88% and selectivity to F2Ac 34%; reaction conditions: batch reactor; 50 °C; acetone/furfural = 10 mol L–1). © 2018 Society of Chemical Industry

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Section: Resultssupporting

confidence: 88%

Section: Physicochemical Characteristicsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Pyroaurite‐based MgFe mixed oxides and their activity in aldol condensation of furfural with acetone: effect of oxide composition

Kocík

Frolich

Perková

et al. 2018

J of Chemical Tech & Biotech

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“…Studies have reported that the synthesis method, the conditions of synthesis, the type of cations and structural anions, the metal precursors and the metal ratio M 2+ /M 3+ are determining factors on the properties and applications of LDH [26][27][28][29]. An important element to improve the catalytic activity of LDH is the thermal treatment to form mixed spinel-type oxides, specifically in the production of biodiesel by heterogeneous catalysis [30,31]. The most relevant studies have shown good results of conversion to biodiesel, but these reactions were found to require a long synthesis time, high temperatures or critical conditions, high percentages of catalyst and large amounts of methanol, among other factors.…”

Section: Introductionmentioning

confidence: 99%

“…The modification that has been given to the LDH containing Fe, both in the laminar structure and impregnated, have shown efficient conversion results, but with long reaction times or with systems that require pressure [31,38]. On the other hand, cobalt is a catalytically active element that has been used in many catalytic processes, including transesterification.…”

Section: Introductionmentioning

confidence: 99%

Use of Co/Fe-Mixed Oxides as Heterogeneous Catalysts in Obtaining Biodiesel

et al. 2019

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Catalyst-type mixed metal oxides with different compositions and Co/Fe ratios were obtained from layered double hydroxides to be used as heterogeneous catalysts in the production of biodiesel. The effect of the Co/Fe ratio on the precursors of the catalysts was analyzed, considering their thermal, textural and structural properties. The physicochemical properties of the catalysts were determined by thermogravimetric analysis (differential scanning calorimetry and thermogravimetric), X-ray diffraction, Fourier-transform infrared spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-ray spectroscopy and N2-physisorption. The conversion to biodiesel using the different catalysts obtained was determined by diffuse reflectance infrared Fourier-transform spectroscopy and 1H-Nuclear magnetic resonance spectroscopy, allowing us to correlate the effect of the catalyst composition with the catalytic capacity. The conditions for obtaining biodiesel were optimized by selecting the catalyst and varying the percentage of catalyst, the methanol/oil ratio and the reaction time. The catalysts reached yields of conversion to biodiesel of up to 96% in 20 min of reaction using only 2% catalyst. The catalyst that showed the best catalytic activity contains a mixture of predominant crystalline and amorphous phases of CoFe2O4 and NaxCoO2. The results suggest that cobalt is a determinant in the activity of the catalyst when forming active sites in the crystalline network of mixed oxides for the transesterification of triglycerides, with high conversion capacity and selectivity to biodiesel.

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The utilization of bio-ethanol for production of 1-butanol catalysed by Mg–Al mixed metal oxides enhanced by Cu or Co

Frolich

Malina

Hájek

et al. 2023

Clean Techn Environ Policy

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The Guerbet reaction is a possible way for transformation of ethanol to 1-butanol (important for many kinds of industries), which consists of four steps: dehydrogenation, aldol condensation, dehydration, and hydrogenation. Due to the elimination of possible side-reactions, the selective catalysis is required to favour production of 1-butanol at temperature below 350 °C. The main aim of this work was the ethanol transformation via heterogeneous catalysis using active Mg–Al mixed oxides with copper or cobalt carried out in the microflow reactor in the reaction temperature interval 280–350 °C. The novelty lies in the statistical analysis of results from characterization of catalyst structure and surface with catalysis results providing more sophisticated perspective on the ethanol valorization. The series of Mg–Al catalysts containing copper showed an overall higher conversion of ethanol and selectivity to butanol compared to the series containing cobalt. Major difference of catalytic activity was at low reaction temperatures and at a lower copper content in the Mg–Al matrix, which is significant from the point of view of environmentally clean processes. A multi-step mechanism of the Guerbet reaction involving an aldol condensation was verified for both tested catalysts series and reaction conditions. Graphic abstract

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Statistical evaluation of the mutual relations of properties of Mg/Fe hydrotalcites and mixed oxides as transesterification catalysts

Cited by 17 publications

References 31 publications

Pyroaurite‐based MgFe mixed oxides and their activity in aldol condensation of furfural with acetone: effect of oxide composition

Pyroaurite‐based MgFe mixed oxides and their activity in aldol condensation of furfural with acetone: effect of oxide composition

Use of Co/Fe-Mixed Oxides as Heterogeneous Catalysts in Obtaining Biodiesel

The utilization of bio-ethanol for production of 1-butanol catalysed by Mg–Al mixed metal oxides enhanced by Cu or Co

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