Abstract
In this study, iron-rich mining residue (UGSO) was used as a support to prepare a new Ni-based catalyst via a solid-state reaction protocol. Ni-UGSO with different Ni weight percentages wt.% (5, 10, and 13) were tested for C2H4 dry reforming (DR) and catalytic cracking (CC) after activation with H2. The reactions were conducted in a differential fixed-bed reactor at 550–750 °C and standard atmospheric pressure, using 0.5 g of catalyst. Pure gases were fed at a molar ratio of C2H4/CO2 = 3 for the DR reaction and C2H4/Ar = 3 for the CC reaction. The flow rate is defined by a GHSV = 4800 mLSTP/h.gcat. The catalyst performance is evaluated by calculating the C2H4 conversion as well as carbon and H2 yields. All fresh, activated, and spent catalysts, as well as deposited carbon, were characterized by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), temperature programmed reduction (TPR), and thermogravimetric analysis (TGA). The results so far show that the highest carbon and H2 yields are obtained with Ni-UGSO 13% at 750 °C for the CC reaction and at 650 °C for the DR reaction. The deposited carbon was found to be filamentous and of various sizes (i.e., diameters and lengths). The analyses of the results show that iron is responsible for the growth of carbon nanofilaments (CNF) and nickel is responsible for the split of C–C bonds. In terms of conversion and yield efficiencies, the performance of the catalytic formulations tested is proven at least equivalent to other Ni-based catalyst performances described by the literature.
Highlights
Hydrogen is an energy vector and is mainly used in the synthesis of several chemicals such as methanol, ammonia, and liquid hydrocarbons via the Fischer–Tropsch process
Experiments have shown that the results that give the best yields of carbon and H2 are obtained at a temperature of 550 °C
Ni-UGSO was prepared from a mining residue UGSO and used to produce carbon nanofilaments (CNF) and H2 via CC and dry reforming (DR) reactions
Summary
Hydrogen is an energy vector and is mainly used in the synthesis of several chemicals such as methanol, ammonia, and liquid hydrocarbons via the Fischer–Tropsch process. Concerning carbon nanofilaments (CNF), several studies have shown that they have noteworthy properties, including high surface area, high mechanical resistance, and high electrical and thermal conductivities [1]. This is why research efforts have focused on optimizing and controlling the formation of these types of carbon structures, instead of inhibiting their growth [2]. Carbon formation on catalysts causes the deactivation of the catalyst [3], CNF are shown to grow in such a way that the catalytically active sites maintain their activity [4]. DR reaction has economic interests and an environmental interest, which is the contribution on the sequestration of CO2 —a greenhouse gas [14,15,16,17]
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