Mesoporous silica and carbon based catalysts for esterification and biodiesel fabrication—The effect of matrix surface composition and porosity

Abstract

Mesoporous silica and carbon based catalysts for esterification and biodiesel fabrication-The effect of matrix surface composition and porosity, Applied Catalysis A, 2017. 533, pp.49-58. http://dx. AbstractThe effects of catalyst matrix porosity composition on the catalytic performance have been studied using sulfonated mesoporous SBA-15 silica. The matrix was sulfonated with three different methods: grafting, in situ oxidation, and carbon infiltration. Additionally, unordered sulfonated mesoporous carbon, and the commercial catalysts Amberlite IR-120 and Nafion 117 were tested. The catalytic performance was evaluated in a Fischer esterification using acetic acid and ethanol, as well as in a transesterification of triglycerides (sunflower oil) and ethanol to produce biodiesel. The study shows that for long carbon chains, the effective wetting of the porous catalyst matrix by the reactants is most important for the catalytic efficiency, while for shorter carbon chain, the mass transport of the reagents trough the porous structure is more important. The catalysts were analysed using electron microscopy and physisorption. The study shows that the reactions are faster with carbon infiltrated materials than the silica materials due to a higher concentration of sulfonic groups linked to the carbon. The in situ functionalized SBA-15 is a more efficient catalyst compared to the post grafted one. All the synthesized catalysts outperform the commercial ones in both reactions in terms of conversion.

Growth and Functionalization of Particle-Based Mesoporous Silica Films and Their Usage in Catalysis

“…Introducing sulfonic acid groups in the mesoporous films result in a substantial increase in the catalytic performance of the film. A conversion of ~5 % of acetic acid during 1 hour of reaction, when no sulfonic acid groups are present, is in good agreement with other studies [13]. This value is boosted by a factor of approximately 6 times when sulfonic acid groups are present in the pores.…”

“…The carbon infiltrated SBA-15 was sulfonated according to previous reports [13,26]. Briefly, 0.5 g of SBA-15-CMK-5 was mixed with 25 ml of H 2 SO 4 and heated to 80 °C under reflux overnight.…”

“…addition of swelling agents or altered reaction temperature, the pores can be increased from the regular ~8 nm to > 18 nm [10,11], and the particle morphology changed from fibers to rods or platelets [11,12]. This makes the material attractive in, e.g., catalysis [13,14], enzyme immobilization [15], and sensing [16]. However, the synthesis of mesoporous films using SBA-15 structures most often results in long pores that are aligned parallel to the substrate [17], making them inaccessible.…”

Sulfonic Acid-Functionalized Inorganic Materials as Efficient Catalysts in Various Applications: A Minireview

“…The acidity capacity in mmol g −1 is measured after letting the acid powder balance with a solution of NaCl used as cation exchanger. [88,91,101,102]. The direct titration with NaOH along with the reverse titration with HCl or H 2 SO 4 [103] gives accurate indication of the functionalization degree.…”

Silica Mesoporous Structures: Effective Nanocarriers in Drug Delivery and Nanocatalysts

“…Interestingly, these nanostructures have internal (cylindrical pores) [53] and exterior [54] surfaces that allow selective functionalization for catalytic and drug delivery applications. The main purpose of this review is providing a general knowledge over the recent applications of mesoporous silica as nanocatalyst and carrier for drug delivery.…”