Effect of reduction conditions of Mo-Fe/MgO on the formation of carbon nanotube in catalytic methane decomposition

Hydrogen Production via Methane Decomposition over Alumina Doped with Titanium Oxide-Supported Iron Catalyst for Various Calcination Temperatures

The decomposition of methane has been chosen as an alternative method for producing hydrogen. In this study, 20 % Fe was used as the active metal part of the catalyst. To better comprehend the impact of the supporting catalytic properties, alumina and titania-alumina composite were investigated as supports. Iron-based catalysts were prepared by impregnation method and then calcined at different temperatures (300 °C, 500 °C, and 800 °C). The catalysts were examined at 800 °C under atmospheric pressure with a 15 mL/min total flow rate and 2 : 1 CH4 to N2 feed ratio. The textural and morphological characteristics of the fresh calcined and spent catalysts were investigated. The catalytic activity and stability data demonstrated that Fe supported over TiO2-Al2O3 calcined at 500 °C performed the best of all evaluated catalysts with a more than 80 % hydrogen yield. The Raman spectra result showed that graphitic carbon was produced for all used titanium dioxide catalysts. Moreover, according to transmission electron microscopy (TEM) results, the carbon deposited on the catalysts' surface is carbon nanotubes (CNT).

Development of Ni-Mo carbide catalyst for production of syngas and CNTs by dry reforming of biogas

Biogas has been widely regarded as a promising source of renewable energy. Recently, the direct conversion of biogas over heterogeneous catalysts for the simultaneous production of syngas and carbon nanotubes exhibits a high potential for full utilization of biogas with great benefits. Involving the combined dry reforming of methane and catalytic decomposition of methane, the efficiency of process is strongly depended on the catalyst activity/stability, mainly caused by carbon deposition. In this study, Ni-Mo catalyst is engineered to provide a life-long performance and perform high activity in the combined process. The surface modification of catalysts by a controlled carburization pretreatment is proposed for the first time to produce a carbide catalyst along with improving the catalyst stability as well as the reactivity for direct conversion of biogas. The performance of as-prepared carbide catalysts is investigated with comparison to the oxide and metallic ones. As a result, the Ni-Mo2C catalyst exhibited superior activity and stability over its counterparts, even though the condensed nanocarbon was largely grown and covered on the surface. In addition, up to 82% of CH4 conversion and 93% of CO2 conversion could remain almost constant at 800 °C throughout the entire test period of 3 h under a high flowrate inlet stream of pure biogas at 48,000 cm3 g-1 h-1. The XPS spectra of catalysts confirmed that the presence of Mo2C species on the catalyst surface could promote the stability and reactivity of the catalyst, resulting in higher productivity of carbon nanotubes over a longer time.