Microwave Assisted Solvent-Free Catalytic Transesterification of Glycerol to Glycerol Carbonate

As a by-product of the biodiesel industries, glycerol has been vastly generated which surpasses the market demand. It is imperative to develop an efficient glycerol valorization processes in minimizing the net energy requirement and intensifying the biodiesel production. In this study, base-catalyzed transesterification of glycerol with dimethyl carbonate using microwave irradiation as heating method to produce glycerol carbonate was conducted by varying grades of glycerol, i.e. 70%, 86% and 99% purity, that is obtained from biodiesel plant. Metal oxide catalysts were used with varying operating parameters including reaction time, DMC/glycerol molar ratio, catalyst weight %, temperature and stirring speed. From the study on the effect of different operating parameters it was found that the type of catalyst used has the most significant effect on the transesterification reaction. Amidst the metal oxide catalysts examined, CaO gave the best performance. This study indicates the feasibility of producing glycerol carbonate using different grade of glycerol in both conventional thermal activation and microwave irradiation with CaO as catalyst. Microwave assisted transesterification (MAT) of glycerol into glycerol carbonate has demonstrated itself as an energy efficient route by achieving 94.2% yield of GC at 65°C, 5 minutes reaction time, 1 wt% CaO and DMC/glycerol molar ratio of 2. The advantages of MAT transesterification route has made the direct utilization of bioglycerol from biodiesel production without the need of purification. This has marked a more economical and less-energy intensive glycerol carbonate synthesis route.

Authors:

• Wai Keng Teng
• Gek Cheng Ngoh
• Rozita Yusoff
• Mohamed Kheireddine Aroua
• Joe Shen Heng

Keywords:

• Biodiesel
• glycerol
• glycerol carbonate
• microwave irradiation.

References:

[1] Yang, F., M.A. Hanna, and R. Sun, Value-added uses for crude glycerol-
-a byproduct of biodiesel production. Biotechnology for Biofuels, 2012.
5(1): p. 1-10.
[2] Quispe, C.A.G., C.J.R. Coronado, and J.A. Carvalho Jr, Glycerol:
Production, consumption, prices, characterization and new trends in
combustion. Renewable and Sustainable Energy Reviews, 2013. 27(0):
p. 475-493.
[3] Nguyen, N., Economic Analysis of Biodiesel and Glycerol Carbonate
Production Plant by Glycerolysis. Journal of Sustainable Bioenergy
Systems, 2013. 3(03): p. 209.
[4] Teng, W.K., et al., A review on the performance of glycerol carbonate
production via catalytic transesterification: Effects of influencing
parameters. Energy Conversion and Management, 2014. 88(0): p. 484-
497.
[5] Patil, P.D., et al., Microwave-Assisted Catalytic Transesterification of
Camelina Sativa Oil. Energy & Fuels, 2009. 24(2): p. 1298-1304.
[6] SDA. Glycerine—An Overview. The Soap and Detergent Association,
Glycerine and Oleochemical Division, 1990, 27.
[7] Perry, R. H., Green, D. W., & Maloney, J. O., 2008. Perry's chemical
engineers' handbook (Vol. 7): McGraw-Hill New York.
[8] Gude, V., et al., Microwave energy potential for biodiesel production.
Sustainable Chemical Processes, 2013. 1(1): p. 5-36.
[9] Pan, S., et al., Transesterification of Glycerol with Dimethyl Carbonate
to Glycerol Carbonate over Na–based Zeolites. Chinese Journal of
Catalysis, 2012. 33(11–12): p. 1772-1777.
[10] Ochoa-Gómez, J.R., et al., Synthesis of glycerol carbonate from glycerol
and dimethyl carbonate by transesterification: Catalyst screening and
reaction optimization. Applied Catalysis A: General, 2009. 366(2): p.
315-324.
[11] Simanjuntak, F.S.H., et al., CaO-catalyzed synthesis of glycerol
carbonate from glycerol and dimethyl carbonate: Isolation and
characterization of an active Ca species. Applied Catalysis A: General,
2011. 401(1–2): p. 220-225.
[12] Islam, A., et al., Advances in solid-catalytic and non-catalytic
technologies for biodiesel production. Energy Conversion and
Management, 2014. 88(0): p. 1200-1218.
[13] Khayoon, M.S. and B.H. Hameed, Mg1+xCa1−xO2 as reusable and
efficient heterogeneous catalyst for the synthesis of glycerol carbonate
via the transesterification of glycerol with dimethyl carbonate. Applied
Catalysis A: General, 2013. 466(0): p. 272-281.