CNT production through the catalytic decomposition of methane on Ni-Cu/Ȗ-Al2O3 at varying Ni-Cu ratios: An ab initio and empirical investigation

College

Gokongwei College of Engineering

Department/Unit

Chemical Engineering

Document Type

Article

Source Title

Journal of Materials Science and Engineering

Volume

A6

Issue

5-6

First Page

148

Last Page

154

Publication Date

2016

Abstract

The decomposition of a single CH4 molecule on Ni-Cu/Ȗ-Al2O3 catalyst surface with varying Ni-Cu ratios for CNT production was determined through ab initio calculations with experimental verification. The structural model was based on empirical XRD characterization data from experimentally-prepared catalysts. Structural relaxation and ab initio molecular dynamics simulations were performed using Materials Studio 2016 DMol3 with the Local Density Approximation – Vosko-Wilk-Nusair (LDA-VWN) exchange correlation functional, Gaussian double zeta plus polarization function basis set (DNP) at 2 × 2 ×1 k-point calculation and orbital cut-off of 3.5 Å, with simulation parameters: T = 1,148 K, time step = 1.9 fs (78.5 a.u.), simulation time of 0.38 ps, with the canonical NVT (constant amount (N), volume (V) and temperature (T)) thermodynamic ensemble and Generalized Gaussian Moment (GGM) thermostat. Ab initio simulation data predicted a decrease in C deposition time with 1:1 Ni-Cu/Ȗ-Al2O3. Empirical data from TGA and SEM analyses confirmed higher CNT yield on 1:1 Ni-Cu/Ȗ-Al2O3. Ab initio calculations indicated an increase in binding energy magnitude with the formation of a Ni-Cu alloy. This increase in energy is attributed to the calculated decrease in crystal size, and was verified by the decrease in average CNT diameter produced on 1:1 Ni-Cu/Ȗ-Al2O3. These findings demonstrate the viability of CTDM as a technology for CNT production, as well as its adaptability to simpler catalytic systems for industrial or commercial applications.

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Disciplines

Chemical Engineering

Keywords

Carbon nanotubes; Methane—Biodegradation

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