Enhanced Long-term Stability and Carbon Resistance of Ni/MnxOy-Al2O3 Catalyst in Near-equilibrium CO2 Reforming of Methane for Syngas Production

Herein we study the catalytic activity/stability of a new generation of cheap and readily available Ni and Al-based catalysts using two Mn precursors, namely Mn(NO 3 ) 2 and Mn(EDTA) 2- complex in the reaction of CO 2 reforming of methane. In this respect, Ni/Al 2 O 3 and two types of Ni/Mn x O y -Al 2 O 3 catalysts were successfully synthesized and characterized using various analytical techniques: TGA, ICP, XRD, BET, FTIR, TPR-H 2 , SEM-EDX, TEM, XPS and TPO-O 2 . Utilisation of Mn(EDTA) 2- as synthetic precursor successfully furnished Ni/Al 2 O 3 -Mn x O y Y (Y = EDTA) catalyst which was more active during CO 2 reforming of methane when compared to Ni/Mn x O y -Al 2 O 3 catalyst, synthesised using Mn(NO 3 ) 2 precursor. Compared to Ni/Mn x O y -Al 2 O 3 , Ni/Al 2 O 3 -Mn x O y Y catalyst afforded near-equilibrium conversion values at 700 o C (ca. 95% conversion for CH 4 and CO 2 , and H 2 /CO = 0.99 over 50 h reaction time). Also, Ni/Al 2 O 3 -Mn x O y Y showed more resistance to carbon formation and sintering; interestingly, after 50 h reaction time, the size of Ni 0 particles in Ni/Mn x O y -Al 2 O 3 almost doubled while that of Ni/Al 2 O 3 -Mn x O y Y remained unchanged. The elevated conversion of CO 2 and CH 4 in conjunction with the observed low carbon deposition on the surface of our best catalyst (Ni/Al 2 O 3 -Mn x O y Y) indicated the presence of MnxOy oxide positioning mediated simultaneous in-situ carbon elimination with subsequent generation of oxygen vacant sites on the surface for more CO 2 adsorption.