Improved structural stability and catalytic performance for CH4 reforming reaction of mesoporous MCM-41 analogs prepared by zeolitic subunits of MOR desilication

We demonstrated a new strategy for the preparation of highly stable mesoporous molecular sieves (TMM) by the desilication of MOR zeolite and self-assembling of the zeolite subunits in Na2O center dot(3.3-3.4) SiO2 aqueous solution. Na2O center dot(3.3-3.4) SiO2 in the aqueous solution plays two roles in the synthesis, one was providing a moderate alkaline medium with buffering effect for the desilication of MOR zeolite, other one was supplementing silica source. The desilication conduction of MOR zeolite was optimized by the adjustment of reaction temperature and time, pH in the solution. TMM were characterized by X-ray diffraction (XRD), N-2 adsorption/desorption (BET), Fourier transformed infrared (FT-IR) and transmission electron microscopy (TEM). The characterization results showed that the characteristics of MOR zeolite, such as double six-membered or five-membered ring subunits, were still preserved in TMM, and TMM possessed well-ordered mesostructure of MOR zeolite crystals. Compared with the pure silica mesoporous molecular sieve (MCM-41, 4-day), the hydrothermal stability of TMM (17-day) was increased by 100% with refluxed water. The significantly improving of TMM hydrothermal stability was due to increase the surface hydrophobicity and the ratio of T12-ring, and decreased remarkably number of hydrophilic silanol groups. After hydrothermal treatment for 17-day, TMM also exhibited more efficient catalytic activation than MCM-41 treated for 4-day in CO2 reforming of methane reaction (700 degrees C). The 5 wt% Ni/TMM-17d-Glu (5 wt% Ni, loading) catalysts prepared by Glucose modified impregnation method exhibited excellent catalytic activity, which were providing 58% CO2 and 47% CH4 conversions at 700 degrees C.