Continuous reactive coupling of glycerol and acetone – A strategy for triglyceride transesterification and in-situ valorisation of glycerol by-product

Abstract

Methyl esters of fatty acids are widely used as biodiesel, a sustainable replacement for petro-diesel.The conventional biodiesel process produces crude glycerol, which constitutes about 10wt% of the total products. This has led to a surplus of crude glycerol due to global increase in biodiesel use, necessitating increased research into sustainable processes that could convert the crude glycerol into higher value-added products. This study investigates biodiesel processes for continuous transesterification of triglycerides to methyl esters, coupled to conversion of the glycerol by-product into solketal, a value-added product, via reaction with acetone in situ. The study was carried out using one-stage and two-stage catalytic transesterification of triacetin and methanol in mesoscale oscillatory baffled reactors (meso-OBRs). The two-stage process involved two meso-OBRs in series packed with Amberlyst TM resin catalysts: a basic Amberlyst TM A26-OH in the first stage to catalyse transesterfication of triacetin with methanol, and an acidic Amberlyst TM 70-SO3H in the second stage to catalyse the coupling of glycerol and acetone to form solketal. One-stage triacetin transesterification and glycerol coupling with acetone was carried out in a meso-OBR packed with the acidic Amberlyst TM 70-SO3H resin. In the two-stage process, the triacetin was converted to 99.1±2.0% methyl acetate and 98.0±1.3% glycerol after 25min residence time in the first reactor and the glycerol was reacted with acetone in the second reactor to achieve 76.5±2.8% solketal conversions after 35min.The single-stage process achieved 48.5±2.7% solketal conversion after 30min. The meso-OBR was operated continuously to achieve high quality steady states and consistent triacetin conversions. The triglyceride transesterification with reactive coupling of glycerol with acetone produces less crude glycerol by-product. This process strategy could be optimised for future biodiesel production.

Techno-Economic Analysis of Glycerol Valorization via Catalytic Applications of Sulphonic Acid-Functionalized Copolymer Beads

“…Elemental analysis of the ST-DVB-SO 3 H copolymer beads showed that it contained 8.63 wt.% of sulfur, corresponding to 2.64 mmol -SO 3 H per gram of copolymer beads. The active site density of the synthesized ST-DVB-SO 3 H copolymer catalyst beads was similar to that measured for the Amberlyst TM 70, which has an acidic capacity of 2.59 mmol H + /g as measured by sulfur content elemental analysis (Eze and Harvey, 2018). It was also observed that the ST-DVB-SO 3 H had similar catalytic activity as the Amberlyst TM 70 (as shown in Figure 8).…”

Glycerol to Solketal for Fuel Additive: Recent Progress in Heterogeneous Catalysts

“…Even though the reaction temperature was considered as mild, the stability of most of the solid catalysts decayed in the presence of water as a byproduct and other impurities (NaCl, methanol) from the glycerol source. The deactivation rate is even higher when the raw glycerol (contaminated with water) was fed to the reactor [106][107][108][109]. Therefore, the viability of the commercial plant depends on (i) the source of feeds [110], (ii) availability of glycerol and other feeds, and (iii) cost of glycerol as the feed.…”

High Conversion of Palm Olein to Ethyl Esters Using a Strong Anion Exchange Resin: Study of the Operational Parameters

“…In summary, although there have been previous studies on the transesterification process using ion exchange resins as a heterogeneous catalyst, some of them with very promising results, 11,[16][17][18][19][20][21][22][23] these studies have not reported the optimal parameters for the ethanolysis reaction or took into account the influence of the resin pretreatment on the conversion results. The main contribution of the present work is the optimization of operational parameters, such as temperature, catalyst amount and molar ratio, in the ethanolysis of vegetable oils using a strong anion exchange resin (Amberlyst A26OH).…”