Characteristics of acetylene cracking on MCM-41 to form carbon materials and their exhaust emission

Hung-Lung Chiang, Fang-Yang Wu, Pei-Hsiu Huang, Ting-Yi Lee

Index: 10.1016/j.micromeso.2018.04.006

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Abstract

Chemical vapor deposition (CVD) was applied to the synthesis of carbon nanotubes with acetylene as the carbon source at 600–800 °C in a nitrogen atmosphere. The mesoporous material MCM-41 was selected as the template, and Ni and Fe were selected as the catalysts. MCM-41 was synthesized for the templates and used for acetylene decomposition to form carbon nanotubes at various temperatures. In Raman spectrometry analysis, the synthesized carbon nanomaterials exhibited an insignificant difference in the degree of graphitization under various pyrolysis temperatures. Results indicated that the liquid products (tar and residues) were the main fraction during acetylene decomposition. For exhaust gas, the concentration of hydrocarbons increased with an increase in temperature. NO concentrations decreased with an increase in temperature. The constituents of exhaust gases (CO, CO2, hydrocarbon and NO) were similar during the synthesis of carbon nanomaterials with various catalysts on templates. The sequence of the abundance of polycyclic aromatic hydrocarbons (PAHs) was C-Ni-MCM-41 > C-Fe-MCM-41 > C-MCM-41 system at the same pyrolysis temperature, and high PAH levels presented for high pyrolysis temperatures. For 52 volatile organic compounds (VOCs), the concentrations were C-MCM-41 > C-Fe-MCM-41 > C-Ni-MCM-41, and low concentration was determined for acetylene pyrolysis at high temperatures.