Zr-promoted Ni nanoparticles in mesoporous silica spheres (NiZr/mSiO2) for catalytic decomposition of methane
Mohammadreza Kosari, Sam Portillo, Shibo Xi, A. J. Pedersen, Abhijit Talpade, Fanxing Li
Abstract
• Mesoporous SiO 2 spheres ( m SiO 2 ) are synthesized and loaded with small and uniform Ni NPs and promoters (Cu, Ce, Zr). • A high-performance and regenerable m SiO 2 -NiZr catalyst at T = 600 °C and WHSV = 24 L·g cat –1 ·h −1 . • Zr promotes Ni reducibility, higher activity, and less tip-growth for CNTs, but expedites the deactivation rate. • CNTs were formed with uniform diameters and high quality. Catalytic decomposition of methane (CDM) is a promising method for producing carbon nanotubes (CNTs) and H 2 at-scale, with net-zero CO 2 emission. Herein, a highly active CDM catalyst is presented comprised of inert mesoporous silica spheres ( m SiO 2 ) as a support loaded with Ni nanoparticles (NPs) and dopants, resulting in high CH 4 conversion and potential inhibition of tip-growth CNTs. Specifically, uniformly dispersed Ni NPs onto m SiO 2 promoted by scant Zr deposition (rendering NiZr/ m SiO 2 ) exhibited decent reducibility and an excellent H 2 production rate (4.52 mol H2 ·g Ni –1 ·h −1 at T = 600 °C and GHSV = 24 L·g cat –1 ·h −1 ). As the best-performing catalyst, 10Ni0.2Zr/ m SiO 2 exhibited satisfactory long-term stability with a low deactivation rate and cyclability performance with marginal activity loss over 10 cycles. Besides, the CNTs growth mode from tip-growth to base-growth could be switched by altering the synthetic chemistry of inert m SiO 2 but at the expense of catalytic activity.