Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Dec 13:6:625.
doi: 10.3389/fchem.2018.00625. eCollection 2018.

Experimental Determination of Optimal Conditions for Reactive Coupling of Biodiesel Production With in situ Glycerol Carbonate Formation in a Triglyceride Transesterification Process

Luma Sh Al-Saadi  1 , Valentine C Eze  1 , Adam P Harvey  1
Affiliations

Experimental Determination of Optimal Conditions for Reactive Coupling of Biodiesel Production With in situ Glycerol Carbonate Formation in a Triglyceride Transesterification Process

Luma Sh Al-Saadi et al. Front Chem. .

Abstract

This study investigated a reactive coupling to determine the optimal conditions for transesterification of rapeseed oil (RSO) to fatty acid methyl ester (FAME) and glycerol carbonate (GLC) in a one-step process, and at operating conditions which are compatible with current biodiesel industry. The reactive coupling process was studied by transesterification of RSO with various molar ratios of both methanol and dimethyl carbonate (DMC), using triazabicyclodecene (TBD) guanidine catalyst and reaction temperatures of 50-80°C. The optimal reaction conditions obtained, using a Design of Experiments approach, were a 2:1 methanol-to-RSO molar ratio and 3:1 DMC-to-RSO molar ratio at 60°C. The FAME and GLC conversions at the optimal conditions were 98.0 ± 1.5 and 90.1 ± 2.2%, respectively, after 1 h reaction time using the TBD guanidine catalyst. Increase in the DMC-to-RSO molar ratio from 3:1 to 6:1 slightly improved the GLC conversion to 94.1 ± 2.8% after 2 h, but this did not enhance the FAME conversion. Methanol substantially improved both FAME and GLC conversions at 1:1-2:1 methanol-to-RSO molar ratios and enhanced the GLC separation from the reaction mixture. It was observed that higher methanol molar ratios (>3:1) enhanced only FAME yields and resulted in lower GLC conversions due to reaction equilibrium limitations. At a 6:1 methanol-to-RSO molar ratio, 98.4% FAME and 73.3% GLC yields were obtained at 3:1 DMC-to-RSO molar ratio and 60°C. This study demonstrates that formation of low value crude glycerol can be reduced by over 90% compared to conventional biodiesel production, with significant conversion to GLC, a far more valuable product.

Keywords: FAME; biodiesel; design of experiment; glycerol carbonate; reactive coupling.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Reaction of triglyceride and DMC.
Figure 2
Figure 2
Contour plots for the effect of DMC, methanol, and temperature on the FAME yields for reactive coupling of RSO transesterification with in situ crude glycerol valorisation to GLC. (A) Interaction between DMC and MeOH to RSO molar ratio at 65°C, (B) interaction between temperature and methanol to RSO molar ratio at 2DMC and (C) interaction between temperature and DMC at 1 MeOH.
Figure 3
Figure 3
Contour plots for the effect of DMC, methanol, and temperature on the GLC yields for reactive coupling of RSO transesterification with in situ crude glycerol valorisation to GLC. (A) Interaction between temperature and MeOH at 2 DMC, (B) interaction between DMC and MeOH to RSO molar ratio at 65°C and (C) interaction between temperature and DMC at 1 MeOH.
Figure 4
Figure 4
FAME and GLC yields for reactive coupling of RSO transesterification with 2:1 methanol to RSO molar ratio, 3:1 DMC to RSO molar ratio, 60°C reaction temperature, and 5 wt% TBD guanidine.
Figure 5
Figure 5
Proposed reaction scheme for triglyceride transesterification with methanol and in situ reactive coupling of the by-product glycerol with DMC to form GLC.
Figure 6
Figure 6
Conductivity of methanol at different TBD guanidine molar concentrations.
See this image and copyright information in PMC

References

    1. Ashby R., Solaiman D. Y., Foglia T. (2004). Bacterial poly(Hydroxyalkanoate) polymer production from the biodiesel co-product stream. J. Polymers Environ. 12, 105–112. 10.1023/B:JOOE.0000038541.54263.d9 - DOI
    1. Ayoub M., Abdullah A. Z. (2012). Critical review on the current scenario and significance of crude glycerol resulting from biodiesel industry towards more sustainable renewable energy industry. Renew. Sustain. Energy Rev. 16, 2671–2686. 10.1016/j.rser.2012.01.054 - DOI
    1. Bromberg L., Fasoli E., Alvarez M., Hatton T. A., Barletta G. L. (2010). Biguanide-, imine-, and guanidine-based networks as catalysts for transesterification of vegetable oil. Reactive Funct. Polym. 70, 433–441. 10.1016/j.reactfunctpolym.2010.04.003 - DOI - PMC - PubMed
    1. BSI (2003). Fat and Oil Derivatives - Fatty Acid Methyl Esters (Fame) For Diesel Engines - Determination of Esters and Linolenic Acid Methyl Ester Contents, in Designation BS EN 14103. London.
    1. Canakci M., Van Gerpen J. (2003). A pilot plant to produce biodiesel from high free fatty acid feedstocks. Trans. Am. Soc. Agri. Eng. 46, 945–954. 10.13031/2013.13949 - DOI

LinkOut - more resources