Influence of atomic structure on the nano-nickel-based catalyst activity produced by solution combustion synthesis in the hydrogenation of maleic acid

Effects of Precursor Concentration in Solvent and Nanomaterials Room Temperature Aging on the Growth Morphology and Surface Characteristics of Ni–NiO Nanocatalysts Produced by Dendrites Combustion during SCS

“…Figure 1d shows the selected area electron diffraction (SAED) pattern of the same sample. The polycrystalline diffraction rings, indicated by the arrows, corresponded to 0.241 nm (NiO), 0.209 nm (NiO), 0.203 nm (Ni), 0.176 nm (Ni), 0.148 nm (NiO), 0.126 nm (NiO), 0.124 nm (Ni), 0.106 nm (Ni), and 0.104 nm (NiO), being in agreement with our previous work [40]. Figure 2a,b exhibits high-resolution TEM images of the large and small crystallite regions, respectively.…”

“…Thus, the concentration of the initial mixture of Ni(NO 3 ) 2 and glycine in water plays a significant role in the nano-catalyst microstructure. As it has been previously discussed [40] for this system, the catalytic activity (for the samples prepared with 50, 75, and 100 mL of water) increases as the water content also increases, indicating a connection to the reduction of the nano-crystallites sizes, a parameter that affects the catalysts' specific surface areas. The dendrites' growth conditions appear to be the main factor that is responsible for the observed changes in the crystallite size of the samples, as their structure depends on the concentration of nickel nitrate and glycine in the water.…”

Review of Recent Studies on Solution Combustion Synthesis of Nanostructured Catalysts

“…A major synthesis example is the production of ammonia, which is prepared via the Haber process of nitrogen hydrogenation . Furthermore, in the market of food processing, among the well‐known catalytic applications is the fats hydrogenation over nickel catalysts for margarine synthesis …”

“…It is interesting to note that, for the catalyst made with 75 mL water, the distinction between site groups B and C is not particularly clear indicating that they are possibly of similar structure. Notably, it was found that NiO acted as an enabling carrier for the metallic nickel in such catalysts; when NiO was not present in the materials, the nickel‐containing catalysts were mostly inactive …”

“…The employed quantity of water for the precursor SCS solution has typically been considered to have minor effect to the final product. However, Xanthopoulou et al found for the first time that the concentration of nitrates in the initial solution influences the characteristics and properties of the as‐synthesized Ni‐based catalysts, such as their composition, crystallite size (Figure ), pores size distribution, and surface area. It was concluded that the properties of the hydrates, which are formed in the aqueous electrolyte solutions with various concentrations, are affected by the substitution and ion implantation as well as the method of their formation and other ion complexes, resulting in the detected impact of water's volume on the properties of the final SCS product.…”