Effect of Manganese on Co–Mn/CNT Bimetallic Catalyst Performance in Fischer–Tropsch Reaction

Abstract

Cobalt (Co) catalyst is supported by carbon nanotubes (CNT) using a strong electrostatic adsorption (SEA) method. To promote activity and selectivity as well as find the optimum loading percentage and its effect on catalyst performance, manganese (Mn) has been added to the Co/CNT catalyst. Samples were characterized by a scanning electron microscope (SEM-EDX), transmission electron microscope (TEM), hydrogen temperature programmed reduction (H 2 -TPR), Zeta potential, Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD), and X-ray spectroscopy (XPS). TEM images illustrated an intake of metal particles which were highly dispersed, having a narrow particle size distribution of 6-8 nm to the external and internal CNT support. H 2 -TPR showed a lower temperature reduction with Mn at 420 • C for Fischer-Tropsch synthesis (FTS) reaction. The Co-Mn/CNT catalyst performance test for FTS was performed at a temperature of 240 • C in a fixed-bed micro-reactor at a pressure of 2.0 MPa. The addition of manganese resulted in a lower methane selectivity and a higher C 5+ product with an optimum percentage of 5% of manganese. CO conversion was 86.6% and had a C 5+ selectivity of 81.5%, which was higher than the catalysts obtained using only Co on pretreated CNT.

Beyond confinement effects in Fischer-Tropsch Co/CNT catalysts

“…The reducibility of the catalysts was studied by temperature-programmed reduction. Figure S10 shows °C), which fits well with the data reported in the literature (220-280 °C) [32,33]. The lower reduction temperature observed for the first peak of the ex-nitrate catalysts could be explained by a confinement effect [22,34].…”

Effect of Temperature, Syngas Space Velocity and Catalyst Stability of Co-Mn/CNT Bimetallic Catalyst on Fischer Tropsch Synthesis Performance

“…Some researchers recorded the influence of operating conditions on the product selectivity for cobalt-based catalysts [20,24,25] and revealed that the olefin selectivity of the hydrocarbon product range reduced with rising pressure, which has reported in prior studies [19,21,24]. This study is a continuation of previous research that has been examined and published [26][27][28][29][30]. The current investigation aims to prepare cobalt manganese bimetallic catalysts on CNT substrate employing SEA technique, also to study effects of temperature, syngas space velocity, and catalyst stability through Fischer-Tropsch synthesis by performing Co-Mn/CNT bimetallic catalyst.…”

“…Carbon mass balance was calculated from the moles of carbon entering the reactor relative to the moles of carbonaceous products formed. The advantage and novelty of the current studies were performed by the SEA method for synthesizing Co-Mn catalysts on CNT support for Fischer-Tropsch (FT) reaction, which has not been reported previously [26][27][28][29]. A high percentage of CO conversion and C 5+ selectivity was obtained in the present investigation.…”

Effect of Pressure, H2/CO Ratio and Reduction Conditions on Co–Mn/CNT Bimetallic Catalyst Performance in Fischer–Tropsch Reaction

“…This work is continuation of the same project which is previously investigated and published. In the previous studies X-Ray Diffraction (XRD), Brunauer-Emmett-Teller (BET), X-ray Photoelectron Spectroscopy (XPS), etc characterization preformed and discussed [14][15][16][17]. Characterization techniques performed for FTS catalysts include Transmission electron microscopy (TEM) analysis on a Zeiss LIBRA 200 FE TEM at 200 kV accelerating voltage.…”

“…This work is a continuation of the same project which has previously been investigated and published. Previous works focused on catalyst preparation variables such as effects of catalyst active site confinement in CNT channels, addition of Mn to Co/CNT catalyst, acid and thermal treatment of CNT support, catalyst pH, percentage of Cobalt catalyst loading, calcination condition and catalyst particle size [14][15][16][17]. The present study aims to prepare a CNT-supported cobalt manganese bimetallic catalyst using the SEA method and focus on the study of the effect of Fischer-Tropsch reaction parameters such as pressure, H2/CO ratio, and reduction conditions on the performance of Co-Mn/CNT bimetallic catalyst.…”