Study of selective hydrogenation of biodiesel in a DBD plasma reactor

Abstract

In order to achieve the selective hydrogenation of biodiesel at room temperature and under normal pressure, we researched the upgrading of soybean biodiesel using a dielectric-barrier discharge (DBD) reaction system. Using Raney-Ni as the hydrogenation catalyst, the effects of the operating parameters on the hydrogenation depth and the selectivity of biodiesel were systematically analyzed. The results show that the polyunsaturated components in soybean methyl ester were reduced by 57.04%, and that the polyunsaturated components were hydrogenated to monounsaturated components with a selectivity of 77.75%. Based on the gas chromatography and mass spectrometry (GC-MS) test results, we established a kinetic model for biodiesel hydrogenation. A comparison of the calculated and experimental results shows that the hydrogenation of the biodiesel can be described by a quasi first-order reaction model. The calculated reaction rate constants indicate that under DBD plasma reaction conditions, the hydrogenation of biodiesel has high selectivity for the formation of monounsaturated components.

Upgrading palm biodiesel properties via catalyst‐free partial hydrogenation using needle‐plate dielectric barrier discharge plasma torch

“…The DBD plasma torch used in the present study is a needle‐plate electrode configuration. Na et al 64 found that this configuration was an ion source (H + ) for the ionization process and that the main cause of hydrogen ionization is inelastic collisions as mentioned by Zhao et al 32 Hydrogen ions (H + ) should be the dominant species in the generated plasma responsible to react with unsaturated FAMEs (Figure 11A).…”

“…63 The DBD plasma torch used in the present study is a needle-plate electrode configuration. Na et al 64 found that this configuration was an ion source (H + ) for the ionization process and that the main cause of hydrogen ionization is inelastic collisions as mentioned by Zhao et al 32 Hydrogen ions (H + ) should be the dominant species in the generated plasma responsible to react with unsaturated FAMEs (Figure 11A). In plasma hydrogenation, hydrogenation, conjugation of double bonds, Diels-Alder reaction and cracking reaction are considered probable mechanisms by H radicals/H ions as suggested by Kongprawes et al 33 and Wongjaikham et al 49 Figure 11 demonstrates the suggested DBD plasma torch mechanisms for FAME hydrogenation.…”

“…41 Higher input power resulted in more plasma density and a greater number of hydrogen ions (H + ) available to fill in the C═C bonds. Zhao et al 32 found that as the voltage increased, the hydrogen ionization level and active hydrogen also increased, resulting in a progressive improvement in biodiesel hydrogenation. The needleplate DBD plasma torch may generate more active hydrogen ions compared to parallel-plate DBD because of the higher discharge voltages at the optimal input power.…”

“…Up until now, very limited studies have focused on partial hydrogenation of FAMEs using DBD plasma. Zhao et al 32 used a coaxial cylindrical DBD reactor for selective catalytic hydrogenation of soybean biodiesel over the Raney‐Ni catalyst at room temperature and 0.1 MPa of hydrogen pressure. Atomic hydrogen species from the plasma reacted with unsaturated FAMEs on the active sites of the catalyst with high selectivity for C18:1.…”

Experimental and simulated investigation of microdischarge characteristics in a pin-to-pin dielectric barrier discharge (DBD) reactor

“…Atmospheric pressure air dielectric barrier discharge (APADBD) is a burgeoning method for nonthermal plasma generation and has been applied to gas-phase conversion [1][2][3], plasma-assisted combustion [4][5][6], plasma medicine [7][8][9], active flow control [10][11][12], etc. Typically, an alternating current (AC) supply with a frequency of a few kHz is applied to excite APADBD [13].…”