Thermal decomposition and cobalt species transformation of carbon nanotubes supported cobalt catalyst for Fischer-Tropsch synthesis

Highly Dispersed CoO Embedded on Graphitized Ordered Mesoporous Carbon as an Effective Catalyst for Selective Fischer–Tropsch Synthesis of C5+ Hydrocarbons

Herein, we report the high Fischer–Tropsch synthesis performance of the Co-based catalysts supported on graphitized ordered mesoporous carbon (GMC-900) by using a facile strategy. Compared with CMK-3 and active carbon (AC), the obtained GMC-900 by using pollution-free soybean oil as a carbon source exhibited enhanced catalytic performance after loading Co species due to its highly crystallized graphitic structure and uniform dispersion of CoO. As a result, Co/GMC-900 was an effective catalyst with the maximum C₅₊ selectivity of 52.6%, which much outperformed Co/CMK-3 and Co/AC. This research provides an approach to produce advanced Co-based catalysts with satisfactory performance for efficient Fischer–Tropsch synthesis.

In Situ Growth of Novel Graphene Nanostructures in Reduced Graphene Oxide Microspherical Assembly with Restacking-Resistance and Inter-Particle Contacts for Energy Storage Devices

Graphene is extensively investigated for various energy storage systems. However, the very low density (<0.01 g cm^-3 ) of graphene nanosheets has hindered its further applications. To solve this issue, a controlled assembly of 2D graphene building blocks should be developed into graphene microspheres with high packing density, and restacking of graphene should be prevented to ensure an electrochemically accessible surface area during the assembly. Furthermore, graphene microspheres should have multiple 1D external conductive architecture to promote contacts with the neighbors. This study reports in situ growth of novel graphene nanostructures in reduced graphene oxide microspherical assembly (denoted as GT/GnS@rGB) with restacking resistance and interparticle contacts, for electrochemical energy storage. The GT/GnS@rGB showed high gravimetric (231.8 F g^-1 ) and volumetric (181.5 F cm^-3 ) capacitances at 0.2 A g^-1 in organic electrolyte with excellent rate capabilities of 94.3% (@ 0.2 vs 10 Ag^-1 ). Furthermore, GT/GnS@rGB exhibited excellent cycling stability (96.1% of the initial capacitance after 100 000 charge/discharge cycles at 2 A g^-1 ). As demonstrated in the electrochemical evaluation as electrode materials for electrical double-layer capacitors, unique structural and textural features of the GT/GnS@rGB would be beneficial in the use of graphene assembly for energy storage applications.

Effect of pH, Acid and Thermal Treatment Conditions on Co/CNT Catalyst Performance in Fischer–Tropsch Reaction

Multiwalled carbon nanotubes (CNT) supported cobalt oxide was prepared as a catalyst by strong electrostatic adsorption (SEA) method. The CNT support was initially acid- and thermal-treated in order to functionalize the support to uptake more Co clusters. The Co/CNT were characterized by a range of analytical methods including transmission electron microscopy (TEM), temperature programmed reduction with hydrogen (H2-TPR), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, atomic absorption spectroscopy (AAS), Zeta sizer particle size analysis and Brunauer–Emmett–Teller (BET) surface area analysis. TEM images showed cobalt particles were highly dispersed and impregnated at both exterior and interior walls of the CNT support with a narrow particle size distribution of 6–8 nm. In addition, the performance of the synthesized Co/CNT catalyst was tested using Fischer–Tropsch synthesis (FTS) reaction which was carried out in a fixed-bed micro-reactor. H2-TPR profiles indicated the lower reduction temperature of 420 °C was required for the FTS reaction. The study revealed that cobalt is an effective metal for Co/CNT catalysts at pH 14 and at 900 °C calcination temperature. Furthermore, FTS reaction results showed that CO conversion and C5+ selectivity were recorded at 58.7% and 83.2% respectively, which were higher than those obtained using a Co/CNT catalyst which pre-treated at a lower thermal treatment temperature and pH.

Sintesis dan Karakterisasi CNT (Carbon Nanotube) Berdopan Logam Kobalt

Telah dilakukan penelitian sintesis dan karakterisasi CNT (Carbon Nanotube) dengan doping logam kobalt. Penelitian ini bertujuan untuk menentukan karakter CNT sebelum dan setelah didoping dengan variasi konsentrasi logam 10%, 20%, 30%, 40% dan 50%. Metode yang digunakan pada penelitian ini adalah impregnasi basah yang meliputi perendaman pada larutan logam dan kalsinasi. Hasil impregnasi dianalisis menggunakan Fourier Transform-Infra Red (FT-IR), GSA (Gas Sorption Analysis), Scanning Electron Microscopy (SEM) dan Energy Dispersive X-Ray Spectroscopy (EDS). Analisis FT-IR menunjukkan adanya vibrasi ulur dari ikatan Co-C dan Co-O.  Hasil GSA menunjukkan bahwa CNT loading 30% mempunyai luas permukaan tertinggi yaitu 69,192 m2/g. Hasil SEM-EDS menunjukkan bahwa morfologi permukaan dinding CNT ditutupi aggregat-aggregat kobalt. Pada hasil EDS fraksi kobalt dihasilkan adalah 1,96 % yang nilainya tidak jauh berbeda dari fraksi Fe yaitu 1,49%. Hal ini menunjukkan bahwa CNT doping logam Co menggunakan metode impregnasi basah tidak efektif.