Search

The effect of Sr addition to LaNiO 3 perovskite catalysts was studied for the steam-CO 2 reforming of methane. X-ray diffraction (XRD) patterns indicate that different ionic radii caused distortion of the perovskite lattice and produced alien phases such as La 2-x Sr x NiO 3±δ and Sr 0.5 La 1.5 NiO 4 . Moreover, these different phases affected reduction behavior. The influence of Sr mainly appeared in the steam-CO 2 reforming of methane reaction. SrO species adsorbed CO 2 during the reaction and produced SrCO 3 , which has a better ability of eliminating carbon sources by producing La 2 O 2 CO 3 , and by this means, carbon formation was significantly suppressed. However, the addition of Sr species covered the support sites leading to large-sized nickel particles by reducing the interaction between the support and active metals, thus the catalytic activity was decreased by an increase in Sr concentration on the catalysts. Therefore, we recommend using a small amount of Sr in the perovskite-based catalysts to obtain superior resistance to carbon deposition with moderate catalytic activity. [ABSTRACT FROM AUTHOR]

Nickel-based catalysts are typically used for syngas production via reforming reactions. The reforming of methane using carbon dioxide, called dry reforming of methane (DRM), is an effective way to produce syngas from these two notable greenhouse gases. However, Ni-based catalysts used for DRM undergo severe coke deposition. In the current study, perovskite-type oxide catalysts were prepared using the modified EDTA-cellulose method and characterized by the N 2 physisorption, TPR, CO 2 -TPD, XRD, TGA, SEM and TEM-EDX techniques. The influence of partial substitution of La by Sr/Ca was investigated in the dry reforming reaction for the production of synthesis gas, and the basicity of the catalysts was varied by substituting the A site with either Sr or Ca, which modified the catalytic activity under the tested conditions. It was found that the perovskite catalysts demonstrated superior carbon resistance during the reaction, with La 0.9 Ca 0.1 Ni 0.5 Fe 0.5 O 3 catalyst exhibiting the best catalytic performance among the prepared perovskite catalysts. [ABSTRACT FROM AUTHOR]

In the last decades, environmental crises and increasing energy demand have motivated researchers to investigate the practical techniques for the production of clean fuels through renewable energy resources. It is essential to develop technologies to utilize glycerol as a byproduct derived from biodiesel. Glycerol is known as a sustainable and clean source of energy, which can be an alternative resource for the production of value-added chemicals and hydrogen. The hydrogen production via steam reforming (SR) of glycerol using Ni-based catalysts is one of the promising approaches for the entry of the hydrogen economy. The purpose of this review paper is to highlight the recent trends in hydrogen production over Ni-based catalysts using the SR of glycerol. The intrinsic ability of Ni to disperse easily over variable supports makes it a more viable active phase for the SR catalysts. The optimal reaction conditions have been indicated as 650–900 °C, 1 bar, and 15 wt% Ni in catalysts for high glycerol conversion. In this review paper, the effects of various supports, different promoters (K, Ca, Sr, Ce, La, Cr, Fe), and process conditions on the catalytic performance have been summarized and discussed to provide a better comparison for the future works. It was found that Ce, Mg, and La have a significant effect on catalytic performance as promoters. Moreover, SR of glycerol over hydrotalcite and perovskite-based catalysts have been reviewed as they suggest high catalytic performance in SR of glycerol with improved thermal stability and coke resistance. More specifically, the Ni/LaNi0.9Cu0.1O3 synthesized using perovskite-type supports has shown high glycerol conversion and sufficient hydrogen selectivity at low temperatures. On the other hand, hydrotalcite-like catalysts have shown higher catalytic stability due to high thermal stability and low coke formation. It is vital to notice that the primary concern is developing a high-performance catalyst to utilize crude glycerol efficiently. [ABSTRACT FROM AUTHOR]

Steam CO 2 reforming of methane was carried out over cerium substituted perovskite catalysts. Among the catalysts studied, La 0.9 Ce 0.1 NiO 3 showed the best performance with 49% of methane and 14% of CO 2 conversion under the tested conditions. The chemical and structural properties of the catalysts before and after the reaction were studied by N 2 physisorption, X-ray diffraction, CO 2 -TPD, TPH, TPR, TGA and TEM. It was found that most of Ce existed as CeO 2 rather than being incorporated in perovskite lattice because of large difference in ionic radii between La 3+ and Ce 4+ . Few substitution of Ce in A site resulted in high degree of reduction for active Ni species with good catalytic activity which was further decreased with increasing Ce concentration; substitution of large amount of Ce species led to methanation of CO 2 and formation of large nickel cluster. TPH and TGA analysis revealed that Ce substituted catalyst has better resistance to coke deposition compared to non-promoted perovskite catalyst. [ABSTRACT FROM AUTHOR]