Cu-Ni Alloy Nanocomposites For Methane Dry Reforming Catalysis

The economic prosperity and increasing world population areaccompanied with an increasing consumption of energy. Theconsumption of fossil fuels produces substantial amount of CO2, which isstrongly suspected to induce the abnormal climate change. To diminishthe emission of CO2, researches towards utilization of CO2have beenspurred in recently years. CO2reforming of CH4(dry reforming) convertsthe two green house gases (CH4, CO2) to syngas, the feedstock ofFisher-Tropsch synthesis for liquid fuels, which are beneficial to bothenergy and environments.Ni-based catalyst has long been recognized as an effective catalystfor dry reforming (DRM) reaction. The main obstacle for Ni catalyst usedin DRM process is the rapid deactivation due to the coke formation andparticle sintering at high temperatures. Bimetallic systems have beeninvestigated to improve the performance of the catalyst due to thesynergetic effect. Various noble metals (Pt, Pd, Rh) have been added to Nito form bimetallic catalysts for application in DRM catalysis, whichshows improvement in thermal stability and coke resistance. Consideringthe high cost and limited availability of noble metals, their large scale application in industry is limited. Thus, the development of Ni-basedbimetallic catalysts such as Cu-Ni alloy nanocomposites without noblemetals owing desirable coke resistance and long-term stability at hightemperature is needed.Herein， we reported the preparation of two types of Cu-Ninanocatalysts and their catalytic performance in DRM reaction. In thefirst experiment, monodispersed CuNixnanoparticles (12nm)encapsulated in silica were successfully prepared in microemulsion.Catalysts with different Cu/Ni ratios for methane dry reforming (DRM)catalytic reaction were characterized. We found that proper Cu addition tothe Ni-base could restrain RWGS side reaction effectively. The formationof silica shells not only prevents sintering of cores at high temperatures,which prolonged the lifetime of the catalysts, but preservesmonodispersed fine nanoalloy particles during synthetic process. In thesecond experiment, corona Cu-Ni/SiO2nanocomposites with high loadingof monodispersed nanoparticles and a large surface area (400m2/g) wereprepared successfully through a phyllosilicate procedure. We found thatthe morphologies of the nanocomposites can be controlled by appropriateamount of PVP. Among all the samples we have tested, CoronaCuNi3/SiO2showed the best catalytic ability, and possessed a highstability at high temperature, which might be a promising catalyst usingin DRM reaction in the future. In summary, our experiments demonstrate that CuNi alloynanoparticles encapsulated in silica shell and supported on hierarchialSiO2show superior catalytic performance. The Cu-Ni alloynanocomposites can be promising catalyst using in DRM reaction for theindustry application.