Peanut Shell-Derived Carbon Solid Acid with Large Surface Area and Its Application for the Catalytic Hydrolysis of Cyclohexyl Acetate

Abstract

A carbon solid acid with large surface area (CSALA) was prepared by partial carbonization of H3PO4 pre-treated peanut shells followed by sulfonation with concentrated H2SO4. The structure and acidity of CSALA were characterized by N2 adsorption–desorption, scanning electron microscopy (SEM), X-ray powder diffraction (XRD), 13C cross polarization (CP)/magic angle spinning (MAS) nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared spectroscopy (FT-IR), titration, and elemental analysis. The results demonstrated that the CSALA was an amorphous carbon material with a surface area of 387.4 m2/g. SO3H groups formed on the surface with a density of 0.46 mmol/g, with 1.11 mmol/g of COOH and 0.39 mmol/g of phenolic OH. Densities of the latter two groups were notably greater than those observed on a carbon solid acid (CSA) with a surface area of 10.1 m2/g. The CSALA catalyst showed better performance than the CSA for the hydrolysis of cyclohexyl acetate to cyclohexanol. Under optimal reaction conditions, cyclohexyl acetate conversion was 86.6% with 97.3% selectivity for cyclohexanol, while the results were 25.0% and 99.4%, respectively, catalyzed by CSA. The high activity of the CSALA could be attributed to its high density of COOH and large surface area. Moreover, the CSALA showed good reusability. Its catalytic activity decreased slightly during the first two cycles due to the leaching of polycyclic aromatic hydrocarbon-containing SO3H groups, and then remained constant during following uses.

Synthesis and Characterization of Novel Corncob-Based Solid Acid Catalyst for Biodiesel Production

“…Moreover, it also lowers the mass transfer resistance to the flow of reactants from the mouth of the pore to the active site and products from the active site to the surface of the pore. , Furthermore, when the size of the mesoporous material matches the reactant molecular dimension, the reactant will be deeply absorbed into the internal surface of mesoporous material than on the external surface . The decrease in the specific surface area of the I–C–corncob (1268 m 2 /g) after sulfonation; I–C–S–corncob (641 m 2 /g) is due to loading of SO 3 H groups on the surface . The specific surface area of I–C–corncob is 1268 m 2 /g, which is higher than that of C-corncob.…”

“…The specific surface area of I–C–corncob is 1268 m 2 /g, which is higher than that of C-corncob. It shows the effectiveness of the phosphoric acid as an activating agent, and addition of it leads to the form of a porous structure in the activated carbon. , Arancon et al prepared the SAC by sulfonating (sulfonation temperature = 423 K) the valorized corncob (carbonization temperature = 873 K) and obtained a microporous structure with the specific surface area of 120 m 2 /g. Therefore, the present catalyst showed the highest specific surface area (641 m 2 /g) with a coveted mesoporous geometry compared to the catalyst obtained by Arancon et al …”

“…FTIR spectra show the multiple functional groups on the catalysts, and these spectra are in good agreement with other catalysts from various lignocellulosic precursors. [44][45][46]49 The existing broad spectra in the region of 900−1300 cm −1 is due to the C−O stretching of acids, alcohols, ethers, phenols, and esters. More specifically, a small shoulder at 1265 cm −1 in the spectra of I−C−corncob and I−C−S−corncob resembles the characteristics of phosphorus and phospho-carbonaceous compounds.…”

“…These results are in good agreement with the reported FTIR spectra of porous adsorbent derived from the corncob. 46 The band at 1588−1600 cm −1 along with a peak at 3000 cm −1 indicate the CC stretching vibration of the polyaromatic ring 44,45,49 and show the multiple aromatic rings in the carbon structure. 52 IR spectra of corncob and C− corncob contain both aliphatic and aromatic hydrocarbons.…”

“…The acid densities of the synthesized catalysts were estimated by the titration method as given in the literature. 49 SO 3 H group density was determined by sonicating the mixture of 0.25 g catalyst in 30 mL of NaCl solution (0.05 mol/L) for 1 h in an ultrasonic bath at room temperature. After sonication, solids were separated using a centrifuge.…”