The efficient and green synthesis of biodiesel from crude oil without degumming catalyzed by sodium carbonate supported MoS2

Abstract

The transesterification of lecithin with methanol catalyzed by 23 kinds of alkaline salts was investigated for the preparation of biodiesel. Sodium carbonate was confirmed as the best catalyst due to its excellent catalytic performance, environmental friendliness, and great stability. Next, it was successfully immobilized on the surface of hierarchical nanosheets of MoS₂. The prepared catalyst was characterized via XRD, FTIR, SEM, and TEM techniques. After immobilization, the highest specific activity reached 40.58 ± 0.78 U mg_Na2CO3⁻¹, which was 2.43 times higher than that of unsupported Na₂CO₃. Meanwhile, the highest yield reached 99.8%. The excellent performance of the supported catalysts was attributed to a synergistic effect between MoS₂ and the absorbed sodium carbonate. Firstly, sodium carbonate was uniformly dispersed on the surface of MoS₂ to minimize the mass transfer resistance. Secondly, the electron-rich outer layer of MoS₂ promoted the deprotonation of methanol to form methoxy anions. The prepared catalyst was further applied in the transesterification of lecithin-containing triglycerides to prepare fatty acid methyl esters (FAMEs). The experimental results showed that the addition of lecithin would promote the transesterification of triglycerides. The yields of FAMEs were close to 100% in all cases when the lecithin content was increased from 1% to 40%. Hence, this supported sodium carbonate catalyst should be a promising candidate for biodiesel production from crude oil without degumming.