Gc fid gc 2014

Total lipid extraction was carried out following the Bligh‐Dyer method (Bligh and Dyer, 1959). Neutral lipid fractions were separated by thin‐layer chromatography (TLC) (Merck, Darmstadt, Germany) with triolein as the control and developed with hexane/methanol/acetic acid (160:40:4, v/v/v). Polar lipid fractions were separated by two‐dimensional TLC with chloroform/methanol/water (130:50:8, v/v/v) as the first dimension followed by chloroform/methanol/isopropylamine/28% ammonia water (130:70:1:10, v/v/v/v) as the second dimension. Lipid spots were detected under UV light. Each lipid spot was scraped and extracted in 2.5% HCl in anhydrous methanol (Sigma‐Aldrich) at 85°C for 1 h. Pentadecanoic acid was added as the internal standard. The methanolysis‐derived fatty acid methyl esters (FAMEs) were extracted in hexane and analyzed by GC‐FID (GC‐2014, Shimadzu, Kyoto, Japan) that was equipped with a capillary column (BPX70, SGE Analytical Science, Ringwood, Australia). Supelco 37 Component FAME mix (Sigma‐Aldrich) was used as the FAME peak reference standard.

Catalytic activity tests with or without an electric field were conducted using a fixed-bed flow-type reactor with a quartz tube (6.0 mm i.d.), as shown in Fig. 7. The catalysts were sieved to 250–500 µm, and 100 mg of each sample was charged into a reaction tube. For pretreatment, the catalyst was reduced at 773 K for 2 h under a H₂/Ar gas flow (H₂:Ar = 1:2, 75 mL min⁻¹). After the reduction, the furnace temperature was lowered to 423 K. The composition of the reactant feed gas was CO₂:H₂:Ar = 1:1:2 (100 mL min⁻¹). Two stainless-steel electrodes (2.0 mm o.d.) were inserted into each end of the catalyst bed to apply a direct current using a DC power supply. The catalyst bed temperature was directly measured using a thermocouple, which was inserted into the bottom side of the catalyst bed. After removal of the produced water using a cooling trap, product gases, including CO₂, CO, and CH₄, were analyzed using a gas chromatograph-flame ionization detector (GC-FID, GC-2014; Shimadzu Corp.) equipped with a Porapak Q packed column and a methanizer (MTN-1; Shimadzu Corp.). The CO₂ conversion and CO selectivity were calculated by the following equations (Eqs. 2 and 3, respectively):Figure 7

Schematic diagram of the reaction apparatus.

$${\text{CO}}_2\text{conversion}\left(\text{\%}\right)=(F_{\text{CO},\text{out}}+F_{{\text{CH}}_4,\text{out}})/F_{{\text{CO}}_2,\text{in}}\times 100$$ $$\text{CO selectivity}\left(\text{\%}\right)=F_{\text{CO},\text{out}}/{(F}_{\text{CO},\text{out}}+F_{{\text{CH}}_4,\text{out}})\times 100$$

The GC/FID (GC-2014, SHIMADZU Corporation) system was equipped with a flame ionization detector and a HP-5 (Agilent Technologies, Inc., USA) non-polar capillary column (30 m length, 0.32 mm diameter, 0.25 µm film thickness). Helium was used as a carrier gas at 25 mL/min flow rate. The temperature increased from 50 °C to 300 °C within 25 min and held at 300 °C for 10 min.