Abstract
<p class="Default">Nickel catalysts supported on different carriers (θ-Al<sub>2</sub>O<sub>3</sub>, γ-Al<sub>2</sub>O<sub>3</sub>, HZSM-5 with γ-Al<sub>2</sub>O<sub>3</sub>, HZSM-5, and NaX) have been investigated for the partial oxidation of methane. All the supported nickel catalysts showed a high activity for the formation of synthesis gas, and γ-Al<sub>2</sub>O<sub>3</sub> was the most effective among all the tested carriers. The effect of the heat-treatment temperature of the 3 wt.% Ni/γ-Al<sub>2</sub>O<sub>3</sub> catalyst on its catalytic activity was studied, and a considerable decrease in its activity was observed by the heat-treatment of the catalyst at 1000 °C compared with the catalysts prepared by the 300–800 °C – calcination. The XRD analysis suggested the formation of NiAl<sub>2</sub>O<sub>4</sub> that is a non-reducible compound at the high calcination temperature. The addition of a modifier (Co, Ce, or La) to the 3 wt.% Ni/γ-Al<sub>2</sub>O<sub>3</sub> catalyst increased the selectivity to H<sub>2</sub> and CO with the decreasing selectivity to CO<sub>2</sub>, and the highest selectivity to H<sub>2</sub> was obtained by the 5 wt.% NiLa/γ-Al<sub>2</sub>O<sub>3</sub>. The developed 5 wt.% NiLa/γ-Al<sub>2</sub>O<sub>3</sub> catalyst showed a high stability for 30 h for the partial oxidation of methane at 750 °C. The methane conversion reached 95%, selectivity to hydrogen 83% and 52% to carbon monoxide.</p>
Highlights
According to the International Energy Agency (IEA), the demand of natural gas for energy production will increase until 2020
The composition of synthesis gas obtained in the process is more preferable for the production of methanol and liquid products by the Fischer-Tropsch reaction, because the cost of synthesis-gas produced by the partial oxidation of methane is estimated to be almost 1.5 times lower than that produced by steam reforming [6, 7]
Carriers (θ-Al2O3, γ-Al2O3, HZSM-5 with Al2O3, HZSM-5, and NaX) with different properties have been investigated for the partial oxidation of methane
Summary
According to the International Energy Agency (IEA), the demand of natural gas for energy production will increase until 2020. Synthesis gas is produced by the steam-reforming of natural gas, the most promising one of all the known processes for synthesis–gas production is the oxidative conversion of methane. Various nickel-based catalysts, such as Ni-γAl2O3 [14, 15], Ni-M-γ-Al2O3 (M = La [16], Co [17], Rh [18] and Cu [19]), and Ni supported on La2O3, CeLaOx, and CeO2 [20], were investigated for the oxidative conversion of methane. In these reactions, most of the catalysts showed a high activity, and the methane conversion value were in the range of 67–95%. The effects of promoting additives (Co2O3, CeO2, La2O3) on the performance and the physicochemical characteristics of the nickel catalysts were investigated
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