Compositional analyses of Gas to Liquid (GTL) diesel oil and Biomass to Liquid (BTL) diesel oil were carried out at the molecular level using GC-FID and GC-MS. Commercially available reagents and standard samples especially prepared were used as the reference samples for peak assignment in addition to the commercial mass spectrum library. BTL diesel oil was separated into the saturate, olefinic, aromatic, and polar fractions by open column chromatography. BTL diesel oil was also hydrogenated to allow type analysis of the olefinic compounds. GTL diesel oil consisted of only paraffinic compounds,
i.
e., 17 wt% of straight paraffins, 20 wt% of monomethyl paraffins, and 63 wt% of other branched paraffins. About half of the other branched paraffins could be analyzed based on molecular weight and concentrations, but the small quantity of the remainder continuously contributed to drift of the chromatography base line. GC chromatography of BTL diesel oil showed quite low drift of the baseline. BTL diesel oil consisted of 75 wt% of satutates, 22 wt% of olefins, 2.5 wt% of aromatics and 0.88 wt% of polar compounds. The saturate fraction consisted of 60 wt% of straight paraffins, 8.5 wt% of monomethyl paraffins, and 7.5 wt% of other branched paraffins/cycloparaffins. The olefinic fraction mainly consisted of straight 1-olefins and straight 2-olefins (
cis and
trans) with 0.3-0.4 wt% of cycloolefins. After hydrogenation of BTL diesel oil, the contents of straight paraffins increased by 18 wt%, monomethyl paraffins by 2 wt%, and other branched paraffins/cycloparaffins by 2 wt%, indicating that BTL diesel oil contained 18 wt% of straight oleffins, 2 wt% of monomethyl olefins, and 2 wt% of other branched olefins/cycloolefins. BTL diesel oil contained 2.5 wt% of aromatic compounds, consisting of 1.9 wt% of benzenes, 0.4 wt% of tetralins/indanes, and 0.2 wt% of naphthalenes. The polar fraction consisted of alcohols, ketones, aldehydes, and other unknown compounds.
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