Characterization and catalytic behavior of EDTA modified silica nanosprings (NS)-supported cobalt catalyst for Fischer-Tropsch CO-hydrogenation

Abstract

The effect of ethylene diamine tetraacetic acid (EDTA) modification on the physico-chemical properties and catalytic performance of silica nanosprings (NS) supported cobalt (Co) catalyst was investigated in the conversion of syngas (H2 + CO) to hydrocarbons by Fischer-Tropsch synthesis (FTS). The unmodified Co/NS and modified Co/NS-EDTA catalysts were synthesized via an impregnation method. The prepared Co/NS and Co/NS-EDTA catalysts were characterized before the FTS reaction by BET surface area, X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), differential thermal analysis (DTA) and thermogravimetric analysis (TGA) in order to find correlations between physico-chemical properties of catalysts and catalytic performance. FTS was carried out in a quartz fixed-bed microreactor (H2/CO of 2:1, 230°C and atmospheric pressure) and the products trapped and analyzed by GC-TCD and GC-MS to determine CO conversion and reaction selectivity. The experimental results indicated that the modified Co/NS-EDTA catalyst displayed a more-dispersed phase of Co3O4 nanoparticles (10.9%) and the Co3O4 average crystallite size was about 12.4 nm. The EDTA modified catalyst showed relatively higher CO conversion (70.3%) and selectivity toward C6–18 (JP-8, Jet A and diesel) than the Co/NS catalyst (C6–14) (JP-4).