Coke Suppression Of Hydrocarbon Fuel Thermal Cracking Over Perovskite Based Coating

Coke inhibition is one of the key issues for hydrocarbon fuel cracking.In this research,various perovskite based coatings have been prepared in the GH3128 tube??3×0.5 mm×1000 mm?via washcoating.SEM,EDX and XRD were used to characterize the coating.Anti-coking performance of the coatings has been evaluated via thermal cracking of RP-3?700oC,4 MPa,1 g/s,30 min?with the addition of oxy-compounds.The obtained cokes were characterized by SEM and TPO.The gas and liquid products were also measured and the anti-coking mechanism was proposed.Various perovskite coatings have been prepared using the silica as binder.The coating presents a firm structure with the thickness of 4?m.The coking behaviors of RP-3 fuel blended with 5%water on the BaCeO₃ coating have been investigated during supercritical cracking.Coating and water were split to clearly understand the effect of both parameters.93.1%of cokes can be effectively suppressed over the BaCeO₃ coating for fuel cracking with water addition.After water being replaced by the miscible ethanol,anti-coking efficiency of BaCeO₃ coating is decreased to 88.8%.But the system is more stable with smaller system pressure fluctuations.The results of SEM and TPO indicate that perovskite coatings can suppress filamentous cokes.Additionally,both amorphous cokes and tyical coke precursors related to aromatic condensation in liquid products decrease benefiting from the addition of water or ethanol.Bifunctional perovskite coatings consisting of BaWO₄,BaCeO₃,SiO₂ and H₃PW₁₂O₄₀ have also prepared using the silica as binder.The results of SEM,EDX,XRD indicate that BaWO₄,BaCeO₃,SiO₂ and H₃PW₁₂O₄₀ in the 4.2?m coating present an uniform distribution.The effects of ethanol addition on the coking of fuel during thermal cracking in the bifunctional coating tubes were also studied.The optimal amount of ethanol addition was 5 wt%with the anticoking ratio of 96.4%.More than 94%of the cokes can be efficiently suppressed with phosphotungstic acid and perovskite coexisting in the coating.The effects of different oxy-compounds on amorphous cokes deposited in the bifunctional coating tubes were also studied.Besides ethanol,isopropanol,diethyl ether and ethyl acetate can reduce coke deposition over the bifunctional coating.The anti-coking mechanism of bifunction coating coordinating with ethanol has been proposed.The dehydration of ethanol can be catalyzed by the phosphotungstic acid and then the obtained steam participate in the carbon-steam gasification reaction to reduce the amorphous cokes on the coated tube.Additionally,typical coke precursors related to aromatic condensation in liquid products are decreased benefiting from the water or ethanol addition.