Influence of Alkaline and Alkaline Earth Metal Promoters on the Catalytic Performance of Pd–M/SiO₂ (M = Na, Ca, or Ba) Catalysts in the Partial Hydrogenation of Soybean Oil-Derived Biodiesel for Oxidative Stability Improvement

Abstract

Palladium/silica (Pd/SiO2) and Pd–M/SiO2 catalysts, where M stands for sodium (Na), calcium (Ca) or barium (Ba), were studied for their catalytic ability in the partial hydrogenation of soybean oil-derived fatty acid methyl esters (SO-FAMEs) using a semibatch reactor under mild reaction conditions (4 bar hydrogen pressure and 80 °C). The catalytic performance, in terms of turnover frequency (TOF), and the selectivity toward (E)-monounsaturated FAMEs (C18:1) were investigated at 11% and 45% diunsaturated FAME (C18:2) conversion levels. The catalysts were analyzed by X-ray diffractometry, temperature-programmed desorption of carbon dioxide, transmission electron microscopy, pulse chemisorption of carbon monoxide, nitrogen adsorption–desorption, and X-ray photoelectron spectroscopy. On the one hand, the highest TOF was observed with the catalyst with the lowest basic sites on the catalyst surface (Pd–Ba/SiO2) in comparison with the other basic-modified catalysts; on the other hand, the highest selectivity toward (E)-C18:1 was evidently noticed. The oxidative stability of the partially hydrogenated SO-FAMEs (biodiesels) obtained using these catalysts could be improved 2- to 5-fold compared to those of the feed SO-FAMEs.

Low-temperature and atmospheric pressure plasma for palm biodiesel hydrogenation

“…This assisted the reaction to take place at a lower temperature of 80 °C at 0.4 MPa for 4 h. The results showed that the oxidation stability rose from 2 to 11 h and that the cloud point changed from 7 to 10 °C. Moreover, alkaline and alkaline earth metals such as Na, Ca or Ba can be used as modifiers to improve the conversion of polyunsaturated fatty acid 19 . In the case of H-FAME produced from palm FAME, a Pd catalyst on SBA-15 support was also practiced as reported in the study of Chen et al 20 .…”

Advanced zeolite and ordered mesoporous silica-based catalysts for the conversion of CO2to chemicals and fuels

“…Accordingly, MgO has been considered a suitable additive to DRM catalysts improving activity and stability. 894,895 A study of Mg, Mn, K, and Ca additions onto Ni/HY catalysts revealed the improved resistance of the catalyst to coke deposition. 894 Mg, Mn and Ca doping induces an increase in the activity and stability of the Ni/HY catalyst while K doping worsens them with high coke formation and reactor plugging.…”

Sustainable biodiesel generation through catalytic transesterification of waste sources: a literature review and bibliometric survey

“…Other researchers used the NiCoPt promoter over FAU zeolite for the oleic acid esterification reaction. 334 They achieved 93% oleic acid conversion at 343 K. To study the catalytic activity in the partial hydrogenation of soybean oil-derived fatty acid methyl esters and enhance the oxidative stability of biodiesel, Thunyaratchatanon et al 335 employed sodium (Na), calcium (Ca), and barium (Ba) promoters for the Pd/SiO 2 catalyst. The most significant turnover frequency was due to the low basic site density of Pd–Ba/SiO 2 .…”