Anti-coking performance of Cr/CeO2 coating prepared by high velocity oxygen fuel spraying

The coke in the coils has a serious impact on the long-term and stable operation of the ethylene plant. Inhibiting coking of the cracking furnace is an important issue. In this paper, the Cr/CeO2 coatings were prepared on the surface of 310S stainless steel by high-velocity oxygen-fuel (HVOF) spraying. The anti-coking performances of the bare 310S specimen and the Cr/CeO2 coatings were tested by using the pyrolysis of naphtha. The results show that the coating with the thickness of 10–15 μm and a very small number of pores was built up by the obviously deformed splats and the coating/substrate interface is jagged bond. The white area on the surface of Cr/CeO2 coatings mainly includes CeO2. However, the gray area is made of Cr or Cr2O3. Compared with the bare 310S specimen, the coking inhibition rates of coatings are 48.7%, 58.9%, 76.1% and 88.9% when the ratio of Cr and CeO2 powder is 19:1, 9:1, 4:1 and 3:2, respectively. With increasing the relative ratio of CeO2, more white areas without coke are exposed. The CeO2 surface can not only inhibit catalytic coking, but also promote the reaction of water vapor and coke.