Synthesis and performance evaluation of silica-supported copper chromite catalyst for glycerol dehydration to acetol

Abstract

Sol-gel technique was used to prepare silica-supported copper chromite catalyst from acid hydrolysis of sodium silicate. The catalyst was characterized by BET surface area, FESEM, XRD, H 2-TPR and pyridine adsorption by FTIR. The catalyst was activated in a hydrogen atmosphere based on H 2-TPR result. The surface acidity of the catalyst was evaluated by NH 3-TPD and pyridine adsorption. XRD result of reduced catalyst showed the presence of Cu 0 , Cu 1? and Cr 2 O 3 in the catalyst. Glycerol dehydration was carried out at different temperature (180°C to 240°C) from aqueous glycerol solution with the reduced catalyst in a batch reactor. The glycerol conversion was reached 100% with maximum acetol selectivity of 70% for highest Copper chromite loaded (40 wt%) on silica at 220°C in atmospheric pressure. The distilled liquid product was analyzed by high-performance liquid chromatography. Oxidized catalyst and spent catalyst showed lower glycerol conversion with low acetol selectivity than the reduced form of the catalyst. This is due to the cuprous ion in the reduced form of the catalyst, which acts as Lewis acid sites in glycerol dehydration.

Electrochemical Routes for the Valorization of Biomass-Derived Feedstocks: From Chemistry to Application

“…The process of glycerol dehydration to acetol can, in principle, be easily coupled to an electrochemical reactor. The initial chemical process can be performed in both semi-batch reactive distillation (conversion and selectivity higher than 90% were demonstrated on copper chromite catalysts at 240 °C and 98 kPa − ), and in vapor-phase heterogeneous reaction (selectivity of 96% was shown on Cu-SiO 2 catalyst, despite lower conversion ∼66%), where the product can be directly condensed into an electrochemical reactor, possibly without purification steps, depending on final product needs. The sub-products of glycerol dehydration such as formic acid, acetaldehyde, and acrylic acid do not significantly interfere in the electrochemical conversion of hydroxyacetone, though some will be simultaneously converted (acetaldehyde and acrylic acid would be converted into ethanol and propanoic acid, respectively).…”

A Review on Catalytic Dehydration of Glycerol to Acetol

“…The glycerol dehydration reaction did not govern any basic properties of the catalyst and entirely depended on Lewis acid sites of the catalyst [97]. The oxidation state of copper (Cu 1+ ) played the crucial role in the dehydration reaction as it acted as Lewis acid sites in the reaction [98]. Sato et al found that a basic support (MgO, CaO, ZnO) effectively shows low acetol selectivity but an acidic support (SiO 2 , Al 2 O 3 , ZrO 2 , Fe 2 O 3 ) effectively promoted acetol selectively [99].…”

“…The glycerol dehydration reaction did not govern any basic properties of the catalyst and entirely depended on Lewis acid sites of the catalyst 97. The oxidation state of copper (Cu 1+ ) played the crucial role in the dehydration reaction as it acted as Lewis acid sites in the reaction 98. Sato et al.…”

Modelling and optimization of main independent parameters for biodiesel production over a Cu0.4Zn0.6Al2O4 catalyst using an RSM method

“…Nonetheless, its low thermal stability and weak durability at temperatures higher than 300°C indicate that the formation of spinel oxide could improve the thermal stability of catalysts containing Cu. 32,33 Indeed, Cu spinel oxide in the form of CuM 2 O 4 has higher catalytic activity and greater stability. The solution combustion method is one strategy to produce this kind of spinel, which can offer better activity in the esterification process.…”