CO2 reforming of methane over MCM-41-supported nickel catalysts: altering support acidity by one-pot synthesis at room temperature

• A facile one-pot, room temperature synthesis method was used to alter the MCM-41 support acidity.
• It affords Ni-MCM-41 with unprecedented catalytic activity for the CO2 reforming of methane.
• Controlling the acidity allows for the regulation of product selectivity (H2/CO ratio).
• Varying MCM-41 support acidity alters the extent to which the various side reactions occur.

Highly structured neat MCM-41, Na-form, and Al-incorporated MCM-41 mesoporous materials were synthesized using a simple, one-pot procedure at room temperature. The neat MCM-41 material possessed a surface area comparable with other MCM-41 materials prepared using more conventional higher temperature methods. Incorporating Al into the MCM-41 framework increased support acidity while entrapping Na ions in the MCM-41 pores lowered acidity. The neat MCM-41, Na-form, and Al-incorporated MCM-41 were impregnated with 2.5, 5 and 10% Ni and catalytic performance was assessed for CO2 reforming of methane (CH4). XRD, TEM and H2-TPR indicated at low loadings the Ni was highly dispersed on the support, whereby increasing the Ni loading encouraged the formation of larger Ni crystals on the external MCM-41 surface. 2.5% Ni catalysts supported on neat MCM-41 exhibited excellent catalytic activity invoking up to 98% CH4 conversion at 800 °C and 26% at 500 °C. Carbon accumulation on the catalyst was greater at higher Ni loadings although this was not to the detriment of activity over the reaction time-frame. This result coupled with variations in the H2/CO product ratio and CH4/CO2 conversion difference suggested increasing the Ni loading promoted the Boudouard, CH4 cracking and reverse water gas shift side reactions. Incorporating the MCM-41 with either Al or Na lowered catalyst performance with the promoters found to enhance or suppress the side reactions to varying degrees.

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