Effects of Cobalt Loading, Particle Size, and Calcination Condition on Co/CNT Catalyst Performance in Fischer–Tropsch Reactions

Omid Akbarzadeh,Nor Hamizi,Shamima Akhter,Zaira Chowdhury,Md Shalauddin,Yasmin Abdul Wahab,Noor Mohd Zabidi,Zulkifli Aljunid Merican,Mohd Johan,Marlinda Ab Rahman

doi:10.3390/sym11010007

Omid Akbarzadeh, Nor Hamizi + Show 8 more

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https://doi.org/10.3390/sym11010007

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Journal: Symmetry	Publication Date: Dec 22, 2018
Citations: 50	License type: CC BY 4.0

Affiliation: University of Malaya, Universiti Teknologi Petronas

Abstract

The strong electrostatic adsorption (SEA) method was applied to the synthesis of a cobalt (Co) catalyst on a multi-walled carbon nanotube (CNT) support. In order to uptake more of the cobalt cluster with higher dispersion, the CNT was functionalized via acid and thermal treatment. The Co/CNT catalyst samples were characterized by a range of methods including the Brunauer–Emmet–Teller (BET) surface area analyzer, transmission electron microscopy (TEM), X-ray powder diffraction (XRD) analysis, atomic absorption spectroscopy (AAS), and H2-temperature programmed reduction (H2-TPR) analysis. The data from the TEM images revealed that the catalyst was highly dispersed over the external and internal walls of the CNT and that it demonstrated a narrow particle size of 6–8 nm. In addition, the data from the H2-TPR studies showed a lower reduction temperature (420 °C) for the pre-treated catalyst samples. Furthermore, a Fischer–Tropsch synthesis (FTS) reaction was chosen to evaluate the Co/CNT catalyst performance by using a fixed-bed microreactor at different parameters. Finally finding the optimum value of the cobalt loading percentage, particle size, and calcination conditions of Co/CNT catalyst resulted in a CO conversion and C5+ selectivity of 58.7% and 83.2%, respectively.

Highlights

Fischer–Tropsch synthesis (FTS) is known to convert syngas (H2 + CO) to hydrocarbons and can be considered as an alternative choice for the production of eco-friendly fuels and the management of renewable energy resources
In order to optimum pH value of a cobalt nitrate solution for the Co uptake in the carbon nanotube (CNT), the solution pH was find an optimum pH value of a cobalt nitrate solution for the Co uptake in the CNT, the solution adjusted within a range of 2–14, a weighted amount of CNT was added to each of the pre-determined pH was adjusted within a range of 2–14, a weighted amount of CNT was added to each of the pH solutions, and all the mixtures were shaken for 1 h
From the effect of the Co loading, our studies show that the the CNT support, and Co loading of more or less than 10 wt % resulted in a lower C5+ selectivity of highest CO conversion and C5+ selectivity was obtained at 10 wt % cobalt loading on the CNT support, 57.4%

Summary

Introduction

Fischer–Tropsch synthesis (FTS) is known to convert syngas (H2 + CO) to hydrocarbons and can be considered as an alternative choice for the production of eco-friendly fuels and the management of renewable energy resources. Declining of crude oil reserves and abundance of natural gas and coal reserves as feedstock, made FTS process attractive in recent years. Hydrocarbon fuels synthesized with the FTS method contain a very low percentage of sulfur and aromatic rings. Cobalt is one of the most common metallic catalysts for FTS [1]. The dispersion of the size of the cobalt particles on a support, and catalyst reducibility play an important role in catalyst activity. The desired catalyst on a suitably chosen support should be considered together with the Symmetry 2019, 11, 7; doi:10.3390/sym11010007 www.mdpi.com/journal/symmetry

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