A highly-efficient Rh-based La2Ce2O7 catalyst for steam reforming of diesel: Effect of catalyst structure on performance

The development of high-performance catalysts with good coking resistance and sulfur tolerance for diesel reforming has been a big challenge. Generally, the strong metal-support interaction (SMSI) plays a pivotal role in determining the catalytic performance. This study investigated comparatively a supported-type (Rh/La₂Ce₂O₇) and an embedded-type (La₂Ce_1.89Rh_0.11O₇) catalyst, and revealed that lattice-embedding strategy for active metals significantly enhances SMSI and improves catalytic activity. The activity tests demonstrated that the embedded-type catalyst La₂Ce_1.89Rh_0.11O₇ exhibited a better low-temperature activity, achieving a nearly-complete diesel conversion (∼100 %) at 650 °C, whereas the supported-type catalyst only reached ∼85 % conversion at 750 °C. Stability tests in 650–850 °C further confirmed the high stability of La₂Ce_1.89Rh_0.11O₇, with a H₂ production rate of 70.4 % at 850 °C. Characterization of the catalysts confirmed that the embedded type, in which Rh³⁺ was implemented with partially substituted Ce⁴⁺, triggered a strong SMSI effect, inducing electronic reconstruction within the support, i.e. promoting Ce⁴⁺ to Ce³⁺, thus creating a high concentration of oxygen vacancies. Additionally, the highly dispersed Rh nanoclusters (with average size 2.5 nm, dispersity 44.0 %) were formed. All these structural features had collectively resulted in a catalyst of exceptional anti-coking and sulfur-tolerance properties. In summary, this study provided a good example for the oriented regulation of SMSI through lattice-embedding, which offered a useful guidance for the development of high-performance catalysts for on-board hydrogen production from diesel.