Molten salt induced synthesis of Ni-Sn-Al ternary oxide as highly efficient catalyst for low S/C ratio methane steam reforming

Abstract

Until now almost 50% of the world's hydrogen production at industrial level is realized by methane steam reforming (SMR). Traditionally a high steam to carbon ratio (S/C = 2.5–3.0) is needed to reduce coke formation on catalyst surface while adversely derives downsides like high energy input and significant gas dilution. Such dilemma in SMR process could be relieved by using low S/C ratio (<1.0) but instead raises the bar for catalyst anti-coking ability. In this work, we employed a facile method of molten salt with ball milling pretreatment to prepare Ni-Sn-Al ternary oxide. The synthesized sample showed high reaction activity with slight carbon deposition, benefiting from the well-dispersed Ni nanoparticles and the addition of Sn promoter. The molten salt was found to provide liquid environment and thus induce space confinement for Ni dispersion via strong NiO bond. The positive role of SnOx species is evidenced by comparing the catalytic stability of NiAl binary oxide and Ni-Sn-Al ternary oxide, which the latter is with strong coke resistance under the 30-h stability test without obvious deactivation. Time-resolved in-situ DRIFTS reveals different reaction routes over the two catalysts. Our approach offers a new strategy of dissolving the severe coke formation issue during low S/C ratio SMR.