Continuous-Flow Process for Glycerol Conversion to Solketal Using a Brönsted Acid Functionalized Carbon-Based Catalyst

Abstract

The acetalization of glycerol with acetone represents a strategy for its valorization into solketal as a fuel additive component. Thus, acid carbon-based structured catalyst (SO3H-C) has been prepared, characterized and tested in this reaction. The structured catalyst (L = 5 cm, d = 1 cm) showed a high surface density of acidic sites (2.9 mmol H+ g−1) and a high surface area. This catalyst is highly active and stable in the solketal reaction production in a batch reactor system and in a continuous downflow reactor, where several parameters were studied such as the variation of time of reaction, temperature, acetone/glycerol molar ratio (A/G) and weight hourly space velocity (WHSV). A complete glycerol conversion and 100% of solketal selectivity were achieved working in the continuous flow reactor equipped with distillation equipment when WHSV is 2.9 h−1, A/G = 8 at 57 °C in a co-solvent free operation. The catalyst maintained its activity under continuous flow even after 300 min of reaction.

Easy and Fast Production of Solketal from Glycerol Acetalization via Heteropolyacids

“…Acetals are high-value fuel additives, increasing the octane number of the gasolines, and when added to diesel, biodiesel or mixtures, significantly reduce particulate and oxides emissions [ 3 , 4 ]. One promising additive is the 2,2-dimethyl-1,3-dioxolan-4-methanol, known as solketal, whose preparation involves the need for catalytic acidic sites [ 3 , 13 , 14 ]. Here, heterepolyacids (HPAs) with a Keggin structure can have a proeminent role due to their strong acidic sites and tuneable acidity, substituting the traditional environmental harmful and corrosive acids (e.g., HCl, HF, H 2 SO 4 , H 3 PO 4 , FeCl 3 and SnF 2 ) [ 2 , 13 , 15 ].…”

Green Production of Glycerol Ketals with a Clay-Based Heterogeneous Acid Catalyst

“…Clays and modified clays are widely included in chemical reactions such as synthesis and rearrangements of heterocycles, additions reactions, condensations reactions, Diels-Alders reaction, imine synthesis, epoxidation and several more [29,31,32]. In particular, solketal can be produced in a continuous-flow mode in fixed bed reactors [33] at laboratory and pilot-plant bench scales [34]. [19]).…”

Continuous Flow Upgrading of Selected C2–C6Platform Chemicals Derived from Biomass

“…The ketalization of GL with acetone was studied in continuous flow reactor, using either homogeneous or heterogeneous − (Table ) acid catalysts. The formation of the 5-membered ring, 4-hydroxymethyl-2,2-dimethyl-1,3-dioxolane (solketal, 30 ), was always favored and the 6-membered ring 31 , resulting from the capping of the two primary alcohols of glycerol, was detected only in traces (typically 1%, Figure ).…”