Thermal reaction experiments of vacuum residuum were conducted in a micro-batch reactor at 410–480 °C. The product yield variation with time indicated that the secondary cracking reaction mainly occurs in the heavy fraction of the liquid product. A narrow fraction model for low-severity thermal cracking of heavy oil, with the secondary reaction taken into account, was developed. To simplify the reaction network, a pseudo-lump was introduced, which was defined as the fraction generated from the secondary cracking reaction of the heavy fraction (420–540 °C). Furthermore, a sequential method to estimate rate constants in complex models was employed, and the kinetic parameters were estimated by Arrhenius’ law. The model-predicted lump yields agreed well with the experimental values. The ratio of secondary cracking/primary cracking was calculated. The result indicated that, even at the initial stage of the reaction, the ratio in the heavy distillate reaches up to 15–36%; therefore, the secondary cracking reaction cannot be ignored even in low-severity thermal cracking.

Residence time is a key parameter for the cyclones with mass transfer or reaction process. A model for the cylinder-on-cone cyclone was presented to calculate the mean residence time of the liquid phase, based on a force balance on the wall film. This model was validated using an experiment, which measured the residence time of the liquid phase by the hold-up method. The results demonstrated that the predicted residence times are in good overall agreement with the measured values. Furthermore, the liquid residence time decreases obviously with increasing droplets loading, and decreases less with increasing inlet velocity. The liquid residence time increases with the cylinder diameter. The wall film velocity, however, decreases with increasing cylinder diameter, because the perimeter of liquid wall film is directly proportional to the cylinder diameter.

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The induction period is a significant concept for design and operation of the delayed coking process. To simplify the prediction of the induction period and make it applicable to operational analysis and real-time control of the thermal cracking process, a practical model for the induction period of heavy oil during thermal reaction, which is suitable for the non-isothermal reaction in the industrial conditions, was presented. The development of this model was based on the experimental data of five heavy oils. The model parameters were correlated with microcarbon residue (MCR) of heavy oil to improve the model universality. Furthermore, the validity of correlation between MCR and cracking kinetic parameters was proven. The modelpredicted cracking conversion agrees well with the experimental values. The induction period model was employed to predict the induction period of two feedstocks reported in the literature. Results indicated that the induction period model is available for the thermal reaction of these heavy oils.

FeNi-based hybrid materials are among the most representative catalysts for alkaline oxygen evolution reaction (OER), but the modulation of their surface atoms to achieve the optimal catalytic properties is still a big challenge. Here, we report the surface modification of Ni(OH)2/nickel foam (NF)-based electrocatalyst with a trace amount of ferrocene formic acid (FFA) (FFA-Ni(OH)2/NF) for highly efficient OER. Owing to the strong electron interaction and synergistic effects of Fe-Ni heteroatoms, FFA-Ni(OH)2/NF exhibits an overpotential of 311 mV at a current density of 100 mA cm−2. Impressively, the overpotential of FFA-Ni(OH)2/NF at 100 mA cm−2 is 108 mV less than that of bulk phase doped Ni/FFA(OH)2/NF, demonstrating the surprising effect of heteroatomic surface modification. In addition, by introducing a small amount of surface modifier into the electrolyte, the weak surface reconstruction process in the electrochemical process can be fully utilized to achieve obvious modification effects. Therefore, this work fully proves the feasibility of improving catalytic activities of FeNi-based catalysts by modifying surface heterogeneous atom pairs.