(666e) Engineering Mesoporous SiO2 Spheres Supported Ni-Based Nps for Dry Reforming of Methane with CO2

Dry reforming of methane (DRM) could efficiently convert two potent greenhouse gases, i.e. methane and CO₂, into syngas (CO and H₂). Since coke formation is inherent to DRM, there is a continued interest in developing stable and active catalysts with enhanced coke formation resistance and high CH₄ conversion. While metallic nickel is the most used active metal for DRM, support materials are also important in the overall catalyst performance. Among the various options reported to date, mesoporous SiO₂ spheres (mSiO₂) represent an excellent option as an effective support.

Herein, we present a synthetic protocol to synthesize mSiO₂ with different pore structures via modified sol-gel Stöber process and via controlling the gelation conditions (by addition of ethylene glycol), surfactant type (CTAB and CTAC), and base (ammonia and 2-methyl imidazole) as catalyzing agent. By varying the preparation conditions, three mSiO₂ supports (mSiO₂, mSiO₂-EG-A, mSiO₂-EG-M) were designed with varied pore sizes. mSiO₂ manifests a large proportion of micropores in its structure whereas mSiO₂-EG-A and mSiO₂-EG-M primarily exhibited mesoporosity. To load metal NPs, calcined mSiO₂ supports were first functionalized and then exposed to metal precursors to yield metal-loaded mSiO₂ (mSiO₂-M²⁺). Successive air-calcination and H₂-reduction of the samples at elevated temperatures led to well-distributed metal-supported mSiO₂ catalysts. To find highly active catalysts, we tested different bimetallic and trimetallic Ni-based compositions loaded onto one of the supports, where trimetallic compositions were found to have decent reactivity. The reactivity of selected compositions was compared among the mSiO₂ counterparts. For example, for mSiO₂ and mSiO₂-EG-A supported trimetallic NiCoCe with certain metal loadings, H₂:CO ratios of near unity at CH₄ conversion of 87% and 76% were attained at 800°C with a WHSV of 36 L·h^-1·g_cat^-1, respectively. However, there were tangible differences in stability of mSiO₂ catalysts, accentuating the importance of the catalyst porosity nature on performance.