Abstract
To improve the oxidative stability of biodiesel fuel (BDF), the polyunsaturated fatty acid methyl esters (poly-FAME) presented in commercial palm oil-derived biodiesel fuel (palm-BDF) were selectively hydrogenated to monounsaturated fatty acid methyl esters (mono-FAME) under a mild condition (80 °C, 0.5 MPa) using activated carbon (AC)-supported Pd catalysts with a Pd loading of 1 wt.%. The partially hydrotreated palm-BDF (denoted as H-FAME) which has low poly-FAME components is a new type of BDF with enhanced quality for use in high blends. In this study, we reported that the chemical states and particle sizes of Pd in the prepared Pd/AC catalysts were significantly influenced by the Pd precursors, Pd(NO3)2 and Pd(NH3)4Cl2, and thus varied their hydrogenation activity and product selectivity. The 1%Pd/AC (nit) catalyst, prepared using Pd(NO3)2, presented high performance for selective hydrogenation of poly-FAME into mono-FAME with high oxidation stability, owning to its large Pd particles (8.4 nm). Conversely, the 1%Pd/AC (amc) catalyst, prepared using Pd(NH3)4Cl2, contained small Pd particles (2.7 nm) with a little Cl residues, which could be completely removed by washing with an aqueous solution of 0.1 M NH4OH. The small Pd particles gave increased selectivity toward unwanted-FAME components, particularly the saturated fatty acid methyl esters during the hydrogenation of poly-FAME. This selectivity is unprofitable for improving the biodiesel quality.
Highlights
IntroductionHigh contents of saturated fatty acid methyl esters (sat-FAME) worsen the cold flow properties of biodiesel fuel (BDF), and that limits the uses of BDF at low temperatures [4,5,6]
We evaluated the oxidative stability and cold flow properties of the H-FAME samples obtained over the two types of catalysts to compare the effects of the Pd precursor on the catalytic performance of the catalysts
The structural properties of activated carbon (AC) and the Pd/AC catalysts are presented in Table 1, in comparison to a commercial Pd/AC catalyst with a Pd loading of 5 wt.%
Summary
High contents of saturated fatty acid methyl esters (sat-FAME) worsen the cold flow properties of BDF, and that limits the uses of BDF at low temperatures [4,5,6]. In ASEAN, commercial palm oil-derived biodiesel fuel (palm-BDF) is a major source for blending with petroleum diesel. It generally contains approximately 10% of poly-FAME, mostly methyl linoleate with low oxidation stability (denoted as C18:2 ), approximately 40% of monounsaturated fatty acid methyl esters (mono-FAME), mostly methyl oleate with high oxidation stability and suitable cold flow properties (denoted as C18:1 ), and approximately 50% of sat-FAME, mostly methyl palmitate with low cold flow properties (denoted as C16:0 ) [6]. The high blends of B10-30 fuels formulated by HFAME (10–30 vol%) with petro-diesel are suitable for diesel-engine vehicles with high safety and security
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have