Study of structural properties of acid-treated natural sediment and its application as a sustainable catalyst

Abstract

This paper aims to characterize a natural sediment from Bahía Blanca estuary (Argentina) as a new clay source and determine the catalytic capacity after its structural modification by an acid activation process. The acid treatment was performed by employing H 2 SO 4 at different concentrations at 353 K and 60 min. The raw material and acid-activated samples were characterized by XRD, XRF, FTIR, N 2 physisorption, TGA, SEM, EDX, potentiometric titration and pyridine adsorption monitored by FTIR. Moreover, the catalytic activity on lauric acid esterification with methanol was evaluated as a test reaction. From the structural characterization, it was determined that the material studied contains mainly Ca-montmorillonite, illite, albite and quartz. Likewise, the results obtained showed that the acid-treatment impacts the material characteristics, predominantly surface acidity and textural properties. Particularly, it was evidenced that the samples treated under medium acid activation conditions lead to an increase in acid site number and strength and specific surface area and consequently improve the catalytic activity. The results obtained evidenced that this low cost and widely available raw material presents an interesting mineralogical composition with a high clay mineral content. Additionally, the catalytic performance showed a good conversion in the test reaction regarding other heterogeneous catalysts. Hence, considering these results, this natural sediment merits further research on its purification and application.

Investigating the high‐shear mixed catalytic esterification of lauric acid with methanol using central composite design

“…In this way, it is proved that the model has the capacity to reproduce the responses since the maximum conversion value was close to the experimental one. Notice that this LA conversion value is at the level of counterparts reported in the literature based on the information in Table 1 comprising not only homogeneous but also heterogeneous and enzymatic processes 5‐23 . More importantly, the maximum LA conversion in our work was attained at a comparatively milder severity in terms of time (12 min vs 1‐24 h).…”

“…Notice that this LA conversion value is at the level of counterparts reported in the literature based on the information in Table 1 comprising not only homogeneous but also heterogeneous and enzymatic processes. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] More importantly, the maximum LA conversion in our work was attained at a comparatively milder severity in terms of time (12 min vs 1-24 h). For homogeneous T A B L E 8 Quantification of linear and quadratic effects as well as binary interactions with confidence intervals at the 95% probability level for reduced regression model representing the five-factor CCD applied to investigate the HSM-assisted acid esterification of LA with methanol to ML The number 2.030 was taken from the t-test tables at the 95% probability (α = 0.05) and the degrees of freedom of the total error (=36), vide Table 7.…”

Defects of thin CaO(001) on Mo(001): an EPR spectroscopic perspective

“…Alkaline earth metal oxide materials such as CaO and MgO have various technological applications for instance in the fields of gas sensing and 1,2 gas storage, 3 and as a reactive surface or support system in heterogeneous catalysis. [4][5][6][7][8][9][10][11] They have a rocksalt structure with comparable mechanical resistance, 12 thermal stability, optical properties, 13,14 and band gap 15,16 but they differ significantly in their chemical properties e.g. their basicity.…”