No 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.

Comprehensive Summary Non‐oxidative ethane dehydrogenation is a promising route to produce ethene. Herein, PtSn supported catalysts were investigated to achieve better ethane dehydrogenation performance by introduction of different Zr promoters, i.e., framework Zr and ZrO2, to mesoporous MCM‐41. In‐situ XRD, TEM and CO chemisorption show that aggregation of metal particles and phase segregation of Pt3Sn to Pt and PtSn3 at high temperature occur for PtSn/M, leading to bad ethane dehydrogenation activity. Strong interaction between ZrO2 and PtSn species, as proved by XPS, results in restrained metal particles, which promotes the initial reactivity. However, Pt phase generated on surface is disadvantageous for the desorption of produced ethene as indicated by CO‐IR and C3H6‐TPD, and pyridine‐IR and NH3‐TPD indicate strong acidity generated. Both deactivate the catalyst rapidly by deep dehydrogenation and coking. Moderate interaction between PtSn species and Si‐O‐Zr with much weaker acidity is formed when framework Zr is incorporated into MCM‐41, which benefits the dispersion of metal particles, formation of Pt3Sn/Pt species and stabilization of metal species from phase segregation. Outstanding initial ethane conversion and ethene selectivity of ca. 99% were achieved for the optimal PtSn/ZrM, which is more coking‐tolerant and stable by generating graphitic carbon mainly on support instead of active metals.

No abstract

No abstract