Bifunctional Fe-SBA-15-SO₃H Mesoporous Catalysts with Different Si/Fe Molar Ratios: Synthesis, Characterization and Catalytic Activity

Abstract

Bifunctional Fe-SBA-15-SO 3 H mesoporous materials with different Si/Fe molar ratios (3, 5, and 7) have been synthesized via a simple direct hydrothermal method and characterized by XRD, N 2 -adsorption/desorption, TG/DTG and FT-IR techniques, and used as solid acid catalysts in the esterification of lactic acid with methanol. XRD and N 2 sorption characterizations show successful iron doping within the mesoporous channels of SBA-15-SO 3 H. The FT-IR and TG/DTG characterizations also reveal the presence of iron. With the incorporation of Fe ions into the SBA-15-SO 3 H, the acid sites substantially increased because of the selfseparated acidity of the hydrolysis of Fe 3+ solutions. However, in the Si/Fe = 3 molar ratio, the catalytic conversion decreased which is caused by the reduced cooperation effect between the acid pairs due to the weakened hydrogen bonds and collapse of the pore structure. This further suggests that the mesoporous structure decreases with the decrease in Si/Fe ratio.

Acetalization of glycerol with acetone over various metal-modified SBA-15 catalysts

“…This might be due to restructuring of silica and metal precursors, during the step of absorption in the solution. However, the relative intensity of the (110) and (200) peaks decreased or disappeared after the introduction of metal into SBA-15, which might be due to the disruption of the textural uniformity, i.e., hexagonal structure of SBA-15 [25].…”

Impregnation of Fe³⁺ into MCM-41 Pores: Effect of Fe³⁺ Concentration on the Weight Percent of Fe-Frameworks and Fe-Non-Frameworks

“…These Fe 2 O 3 nanoparticles lessen the contrasting scatter of the mesoporous materials pores and frameworks. Erdem et al [45] and Costa et al [46] stated that, in general, the scattering intensity for Bragg reflections decreased when the scattering material The absorption widens with a peak at 2θ = 23° (Fig. 1(B/a-f)), characteristic of the amorphous silica forming the pore walls (ICDD 29-0085).…”

Catalytic Activity of Iron Doped Hexagonal Mesoporous Silica (Fe-HMS) for Degradation of Reactive Green-19 Dye in Water

“…Both samples show typical type-IV isotherm in Figure 2b, mainly due to the capillary condensation and desorption of nitrogen. According to IUPAC classification [19][20][21][22][23][24][25][26], this type of hysteresis with loop and the shift of sharp inflection of P/P 0 are typical for 2D-hexagonal mesoporous material.…”

“…Active sites are needed for the acid while HMS played the role as a good support material reaction. Erdem et al [24] outlined that metal ions itself are involved in self-assembly process as protons. Therefore, the reducing amount of Fe might affect the hydrogen bond in formation of meso-structured, as highlighted in the previous section.…”