Preparation of a Carbon-Based Solid Acid Catalyst by Sulfonating Activated Carbon in a Chemical Reduction Process

Abstract

Sulfonated (SO3H-bearing) activated carbon (AC-SO3H) was synthesized by an aryl diazonium salt reduction process. The obtained material had a SO3H density of 0.64 mmol·g−1 and a specific surface area of 602 m2·g−1. The catalytic properties of AC-SO3H were compared with that of two commercial solid acid catalysts, Nafion NR50 and Amberlyst-15. In a 10-h esterification reaction of acetic acid with ethanol, the acid conversion with AC-SO3H (78%) was lower than that of Amberlyst-15 (86%), which could be attributed to the fact that the SO3H density of the sulfonated carbon was lower than that of Amberlyst-15 (4.60 mmol·g−1). However, AC-SO3H exhibited comparable and even much higher catalytic activities than the commercial catalysts in the esterification of aliphatic acids with longer carbon chains such as hexanoic acid and decanoic acid, which may be due to the large specific surface area and mesoporous structures of the activated carbon. The disadvantage of AC-SO3H is the leaching of SO3H group during the reactions.

Catalytic Activity of Sulfated and Phosphated Catalysts towards the Synthesis of Substituted Coumarin

“…Compared to previous reports [25,[42][43][44][45][46][52][53][54][55][56][57][58], this study also demonstrated that the surface area of the catalytic systems can be manipulated by the synthetic methodology. As can be observed from the obtained data, the acidic SiO 2 catalyst varies in the surface area in comparison to the one prepared from TEOS and displays more activity towards the Pechmann reaction.…”

“…Even though there are several studies addressing the catalytic performance of a variety of heterogeneous solid catalysts in producing coumarin compounds via Pechmann condensation, most of these methodologies suffer from some drawbacks such as long reaction time, swelling tendency, low surface area, stability of the catalysts and their costs [51][52][53][54][55][56][57]. In order to overcome some of these obstacles and as a continuation to our research in developing a new and efficient catalytic protocol for the effective synthesis of coumarins, this report elucidates the synthesis of three new catalytic systems of sulphated and phosphated nanoparticle of silica, titania and silica prepared from TEOS catalysts.…”

A Single Bio-based Catalyst for Bio-fuel and Bio-diesel

“…area of 602m 2 /g gave 78% while the Amberlyst-15 with 4.60 mmol/g SO 3 H groups gave 86% yield. The yield was higher for the longer chain decanoic acid but the leaching of the activated carbon catalyst was a problem [9].…”

“…Better catalytic activity for making biodiesel type molecules, was found to be due to the large surface area and mesoporous structure of the activated carbon [9]. Sulfonation of FDU-15, a mesoporous polymer, produced a catalyst which affected 99% conversion in esterification of palmitic acid using methanol at 343k temperature.…”

“…Also, polymer impregnated with glucose after pyrolysis and sulfonation afforded a catalyst with superior stability and activity due to its higher acid densities [15]. Sulfonated activated carbon was synthesized by reduction of aryl diazonium salt and its activity was compared with Nafion and Amberlyst-15, two commercial sulfonated catalysts ( Figure 13) [9].…”