Effect of characteristic component on diesel steam reforming to hydrogen over highly dispersed Ni–Rh- and Ni-based catalysts: Experiment and DFT calculation study

The complicated components of hydrocarbons and sulfides in diesel lead to carbon deposition and sulfur poisoning of the catalyst and make it difficult to study the catalytic reforming mechanism. Herein, Ni–Rh- and Ni-based catalysts with highly dispersed active metals and particle sizes of approximately 4 nm were prepared continuously in a microfluidic system by co-precipitation method and were used to study the component adaptability of diesel steam reforming. Polycyclic aromatics and sulfides are the main materials affecting the catalytic stability, whereas alkanes with different carbon numbers, cycloalkanes, olefins, and monoaromatics have no obvious influence on the durability. The initial hydrogen yields of 0^# diesel of the China National VI standard over Ni–Rh- and Ni-based catalysts were 142% and 109%, respectively, at a weight hourly space velocity of 4.5 h⁻¹, and the theoretical yield is 151%. After 20 h, the performance degradation of the two catalysts was less than 25% and 35%, respectively. The density functional theory (DFT) calculation results showed that the adsorption capability of Ni–Rh(1 1 1) surface towards CH₂O*, CHO*, and O* was weaker than Ni(1 1 1) surface. The weak binding of active metal surface and oxygen relevant species is an effective pathway to reduce the energy barrier of diesel steam reforming.