Nickel Supported on Alkaline Earth Metal–Doped γ-Al2O3–La2O3 as Catalysts for Dry Reforming of Methane

Effect of Sr Incorporation and Ni Exsolution on Coke Resistance of the Ni/Sr–Al2O3 Catalyst for Dry Reforming of Methane

“…According to the IUPAC classification, the isotherms of all the catalysts were a combination of type II and type IV­(a), with H3-shaped hysteresis loops . The BET specific surface areas and pore volumes decreased upon Sr addition, − ,, which might be driven by the partial collapse or insufficient crystalline growth of the mesoporous structure, as shown in the inset of Figure . , The Sr-free supports exhibit a step-like decrease at the lower limit of desorption hysteresis, whereas the supports containing Sr exhibit a rather slide-like decrease at the lower limit of desorption hysteresis (Figure S1). As suggested by the XRD peaks of Al 2 O 3 , insufficient evolution of crystalline Sr incorporated into the support would lead to a less-developed pore structure, including a less-ordered mesopore, which would cause either a step-like or slide-like decrease at the lower limit of desorption hysteresis …”

“…Metal dispersion also showed the same tendency, particularly Ni EXS /Sr–Al, which had the lowest metal dispersion. In the Sr-promoted catalysts, Ni particles were more agglomerated and unevenly dispersed on the surface of the support, in which the disordered mesopores might facilitate the growth of Ni particles. ,,,, Particularly in the case of the Ni-exsolved catalysts, the space for Ni diffusionexsolution is limited, resulting in intraparticular growth through the weak pore wall.…”

“…According to the IUPAC classification, the isotherms of all the catalysts were a combination of type II and type IV(a), with H3-shaped hysteresis loops. 49 The BET specific surface areas and pore volumes decreased upon Sr addition, [17][18][19]21,50 which might be driven by the partial collapse or insufficient crystalline growth of the mesoporous structure, as shown in the inset of Figure 4. 19,51 The Sr-free supports exhibit a step-like decrease at the lower limit of desorption hysteresis, whereas the supports containing Sr exhibit a rather slide-like decrease at the lower limit of desorption hysteresis (Figure S1).…”

Applications of Al2O3‐Based Nano‐Catalysts in Thermocatalytic CO2 Transformations: Impacts of Surface Acidity and Basicity

“…La 2 O 3 benefits the formation of basic sites on the Al 2 O 3 surface when La is incorporated into Al 2 O 3 lattice structure, acting as a CO 2 reservoir where the adsorption and spillover of CO 2 are both promoted [212–214] . In CO 2 methanation, Ni/Al 2 O 3 modified with moderate amount of La 2 O 3 (4 % and 14 %) possessed a stronger basicity than the unmodified Ni/Al 2 O 3 , which originated from the decrease of Al 3+ −O 2− acido‐basic sites and generation of strongly basic La 3+ −O 2− sites [215] .…”

“…La 2 O 3 benefits the formation of basic sites on the Al 2 O 3 surface when La is incorporated into Al 2 O 3 lattice structure, acting as a CO 2 reservoir where the adsorption and spillover of CO 2 are both promoted. [212][213][214] In CO 2 methanation, Ni/Al 2 O 3 modified with moderate amount of La 2 O 3 (4 % and 14 %) possessed a stronger basicity than the unmodified Ni/Al 2 O 3 , which originated from the decrease of Al 3 + À O 2À acido-basic sites and generation of strongly basic La 3 + À O 2À sites. [215] Similarly, when Ni/Al 2 O 3 was applied in dry reforming of ethane, the addition of La 2 O 3 contributed to a larger content of basic sites with medium and strong strength than Ni/Al 2 O 3 , resulting in a higher CO 2 conversion and syngas yield.…”