Solvent-free heteropolyacid-catalyzed glycerol ketalization at room temperature

Abstract

Currently, the glycerol has been produced in large amounts as biodiesel co-product. Therefore, to develop processes to convert it to more valuable chemicals has attracted significance attention. Glycerol ketals are compounds useful as synthesis intermediates, and fragrances ingredient and mainly, bioadditives for diesel and gasoline, and have been produced trough reactions catalyzed by mineral acids. In this work, we assessed the activity of H 3 PW 12 O 40 heteropolyacid on glycerol ketalization with different ketones at room temperature and in the absence of an auxiliary solvent. The effects of the principal reactional parameters such as the reactants stoichiometry, catalyst concentration, reaction temperature, and type of carbonylic reactant were investigated. H 3 PW 12 O 40 heteropolyacid was much more active than other Brønsted acid catalysts evaluated (i.e. H 2 SO 4 , p-toluenesulfonic acid, H 3 PMo 12 O 40 or H 4 SiW 12 O 40 ) and exhibited high selectivity toward five-membered (1,3-dioxolane) cyclic ketals. Although homogeneous, heteropolyacid catalyst could be recovered and reused without loss activity.

A Review on the Catalytic Acetalization of Bio-renewable Glycerol to Fuel Additives

“…da Silva et al ( 2015b ) evaluated the activity of various Brønsted acid catalysts e.g., HPW, H 2 SO 4 , p-toluene sulfonic acid, PMo, or SiW on glycerol ketalization with different ketones (e.g., propanone, butanone, cyclopentanone, and cyclohexanone) at room temperature and in the absence of an auxiliary solvent. The HPW sample exhibited the highest activity among the Brønsted acid catalysts and exhibited high (> 85%) selectivity toward five-membered (solketal) cyclic ketals.…”

Heteropolycompounds as catalysts for biomass product transformations

“…Under these conditions, it was found that PW was the most active catalyst, achieving a solketal selectivity of 97% at a conversion of 90%. Other ketal derivatives were prepared by using cyclic and acyclic ketones 266 . Supported heteropolyacids have been used as catalysts for this transformation.…”

Highly Efficient Glycerol Acetalization over Supported Heteropoly Acid Catalysts

“…They need to work at approximately 70 °C for a long reaction time. Heteropoly acid H 3 PW 12 O 40 (HPW) was used for solketal synthesis at room temperature, but H 3 PW 12 O 40 is a homogeneous catalyst that is difficult to recycle . The heteropoly acid salt Cs2.5 is water tolerant, possesses an acid strength comparable to that of H 3 PW 12 O 40 and has a high surface area .…”

“…Heteropoly acid H 3 PW 12 O 40 (HPW) was used for solketals ynthesis at room temperature, but H 3 PW 12 O 40 is ah omogeneous catalystt hat is difficultt or ecycle. [10] Theh eteropoly acid salt Cs2.5 is water tolerant, possesses an acid strength comparable to that of H 3 PW 12 O 40 and has ah igh surface area. [19] This materiali sa lso interesting to explore as ac atalyst for glycerol acetalization with acetone.…”

“…A drawback in the formation of acetals and ketals from glycerol is the production of water, which would deactivate the catalyst and facilitate the reversibility of the reaction. To solve this problem, water‐tolerant heterogeneous catalysts, for example zeolite beta, heteropoly compounds, oxides and phosphates and organic–inorganic composites have been studied extensively. As established in our previous study, the heteropoly compound Cs 2.5 H 0.5 PW 12 O 40 (Cs2.5) is very active and selective for glycerol acetalization with aqueous formaldehyde solution (37 %) as it has both a high surface area and high acid strength .…”