Synthesis of long alkyl chain ethers through etherification of ethylene glycol with 1-octene using heteropolyacid supported on K-10 clay

Abstract

Transesterification of vegetable oil with lower alcohols leads to biodiesel formation which is accompanied by ∼10 wt% glycerol as the co-product. Since biodiesel production is going on massive scale across the world, huge quantity of surplus glycerol will be available. Bioglycerol ought to be converted into valuable chemicals and fuels to enable biodiesel to be cost competitive with reference to petro-diesel. Depending on reaction conditions and catalysts, the hydrogenolysis/hydrogenation of glycerol can produce 1,2-propylene glycol, 1,3-propylene glycol, and ethylene glycol; all of which can be further converted into valuable chemicals. The objective of the current work was to convert ethylene glycol to value added etherified products by reaction with 1-octene to 2-(octan-2-yloxy) ethanol (C8 ether) and 1,2-bis(octan-2-yloxy) ethane (C16 ether). Several heterogeneous solid acid catalysts were used such as 20% (w/w) dodecatungstophosphoric acid (DTP) supported on K10 clay (DTP/K10), 20% (w/w) Cs_2.5H_0.5PW₁₂O₄₀/K10 (Cs-DTP/K10), 20% (w/w) DTP/ZrO₂, and Amberlyst-35. Among them 20% (w/w) DTP/K10 was found to be the most efficient catalyst with 72% conversion of ethylene glycol and 80% of selectivity toward 2-(octan-2-yloxy) ethanol (C8 ether). The optimum reaction conditions were as follows: ethylene glycol to 1-octene mole ratio 1:3, catalyst loading 0.03 g/cm³, temperature 140 °C, pressure 1.5 MPa, reaction time 5 h. The effects of different process parameters such as speed of agitation, catalyst loading, mole ratio, temperature, and reusability of the catalyst were studied to examine the efficacy of 20% (w/w) DTP/K10. The process is solvent less, green and clean. Other substrates were also used to enhance the scope of this work.