Methane Dry Reforming by Ni–Cu Nanoalloys Anchored on Periclase-Phase MgAlO_x Nanosheets for Enhanced Syngas Production

Abstract

Stable and efficient syngas production via methane dry reforming is highly desirable as it utilizes two greenhouse gases simultaneously. In this work, active Ni–Cu nanoalloys stably anchored on periclase-phase MgAlO x nanosheets were successfully synthesized by a hydrothermal method. These highly dispersed small Ni–Cu alloys strongly interacted with the periclase-phase MgAlO x nanosheets, on which abundant base sites were accessible. On the optimal catalyst (6Ni6CuMgAl–S), methane and carbon dioxide conversion always reached 85 and 90% at 700 °C under a gas hour speed velocity of 40,000 mL/gcat h for more than 70 h. The hydrogen production rate was maintained at 1.8 mmol/min, and the ratio of H2/CO was kept at approximately 0.96 under a CH4 and CO2 flow rate of 25 mL/min. Coke deposition and Ni sintering were effectively suppressed by the formation of a Ni–Cu alloy, the laminar structure, and the periclase phase of the MgAlO x support. Moreover, the alloy nanoparticles were reconstructed into a segregated Ni–Cu alloy structure in response to the reaction environment, and this structure was more stable and still active. Density functional theory calculations showed that carbon adsorption was inhibited on the segregated Ni–Cu alloy. Furthermore, the experimental thermogravimetric and O2-TPO results confirmed the significant decrease in carbon deposition on the Ni–Cu alloy catalysts.

Ni–Cu Alloy Nanoparticles Confined by Physical Encapsulation with SiO2 and Chemical Metal–Support Interaction with CeO2 for Methane Dry Reforming

“…(2) The alloying of Cu with Ni would influence CH 4 activation on the Ni surface, and the activation energy of CH 4 on the alloy surface was smaller than that on pure Ni surface, which led to the higher CH 4 conversion . (3) Cu modification alleviated the deep cracking of CH x on Ni by the reaction O + CH x → CO + H 2 at the Ni–Cu interface, which contributed to less carbon deposition …”

“…54 (3) Cu modification alleviated the deep cracking of CH x on Ni by the reaction O + CH x → CO + H 2 at the Ni−Cu interface, which contributed to less carbon deposition. 55 3.4. Characterization of Used Catalysts.…”

Optimization of Ni-Based Catalysts for Dry Reforming of Methane via Alloy Design: A Review

“…They determined the optimum conditions: 10 wt % of Ni, 0.83 wt % of Cu, and 750 °C. Xiao et al 235 investigated the DRM activity of different Ni/Cu ratio alloys anchored on the peritectic phase MgAlO x nanosheets. The results of H 2 -TPR (Figure 7a) showed that a higher reduction temperature was required with the addition of Cu, which implied that the interaction of the metal something carriers was enhanced.…”

Tuning Selectivity in the Direct Conversion of Methane to Methanol: Bimetallic Synergistic Effects on the Cleavage of C-H and O-H Bonds over NiCu/CeO2 Catalysts

“…In the field of heterogeneous catalysis by metals, bimetallic catalysts are promising for performing challenging chemical transformations, [26][27][28][29][30][31] and the ensemble effect is a well-known phenomenon. 32 The main feature of this effect is that reactions are sensitive to alloying with a second metal within the group of adjacent atoms of the active metal that are required for forming chemisorption complexes.…”

“…Electronic effects in alloy catalysts refer to the formation of a bond between two different metals that can induce substantial electronic perturbations leading to changes in the chemical and catalytic properties of the bonded metals. [26][27][28][29][30][31] In this context, it is important to establish if bimetallic nickel catalysts, such as NiCu/CeO2, can be useful for tuning the degree of dehydrogenation of CHx (x= 13) species on Ni/CeO2 surfaces, which is critical for preventing coke formation and crucial in the direct partial oxidation of methane to methanol or in the conversion of CHx groups into high value chemicals like olefins or aromatics.…”