Heterogeneous acid catalyst using carbon nitrides: biodieselproduction by esterification of oleic acid with methanol

Abstract: In this study, gCN and melem functionalized with OFGs were synthesized using a simple heat treatment process and modified Hummer’s method as heterogeneous acid catalysts to promote the esterification reaction of oleic acid and methanol (denoted as COOH/gCN and COOH/melem). Here, OFGs were demonstrated to be successfully introduced in the gCN and melem structures through characterization analysis such as XRD, SEM, FT-IR, XPS and NH₃-TPD. The catalytic activity and stability were evaluated in the esterification reaction through repeated batch cycles. Both COOH/gCN and COOH/melem showed high activity over 90 % conversion at the first cycle. However, COOH/gCN catalyst was rapidly deactivated within the fourth cycle, while COOH/mel em catalyst maintained its initial activity until the tenth cycle. In addition, reaction parameters such as methanol to oleic acid ratio, reaction temperature, time, and amount of catalyst were optimized with COOH/melem catalyst.

Funding: This work was conducted under the framework of the research and development program of the Korea Institute of Energy Research (C3-2435).