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Properties of oxide films grown on 25Cr20Ni alloy in air-H_2O and H_2-H_2O atmospheres

Petroleum Science 2014年第1期11卷 147-154页

作者： Wang Shenxiang Cui Lishan Wang Guoqing Zheng Yanjun Wang Hongxia Jia Jingsheng College of Science China University of Petroleum Beijing Research Institute of Chemical Industry

The oxidation kinetics,surface morphology and phase structure of oxide films grown on 25Cr20Ni alloy in air-H2O and H2-H2O atmospheres at 900 ℃ for 20 h were *** anti-coking performance and resistance to carburization of the two oxide films were compared using 25Cr20Ni alloy tubes with an inner diameter of 10 mm and a length of 850 mm in a bench scale naphtha steam pyrolysis *** oxidation kinetics followed a parabolic law in an air-H2O atmosphere and a logarithm law in a H2-H2O atmosphere in the steady-state *** oxide film grown in the air-H2O atmosphere had cracks where the elements Fe and Ni were enriched and the un-cracked area was covered with octahedral-shaped MnCr2O4 spinels and Cr1.3Fe0.7O3 oxide clusters,while the oxide film grown in the H2-H2O atmosphere was intact and completely covered with dense standing blade MnCr2O4 *** the pyrolysis tests,the anti-coking performance and resistance to carburization of the oxide film grown in the H2-H2O atmosphere were far better than that in the air-H2O *** mass of coke formed in the oxide film grown in the H2-H2O atmosphere was less than 10％ of that in the air-H2O *** Cr1.3Fe0.7O3 oxide clusters converted into Cr23C6 carbides and the cracks were filled with carbon in the oxide film grown in the air-H2O atmosphere after repeated coking and decoking tests,while the dense standing blade MnCr2O4 spinels remained unchanged in the oxide film grown in the H2-H2O *** ethylene,propylene and butadiene yields in the pyrolysis tests were almost the same for the two oxide films.

关键词： 25Cr20Ni alloy air-H2O H2-H2O oxide film anti-coking resistance to carburization

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Oxidation of Fe-Cr-Ni Alloys in a Low Oxygen Partial Pressure Atmosphere to Mitigate Coke Formation

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China Petroleum Processing & Petrochemical Technology 2023年第3期25卷 49-59页

作者： Wang Hongxia Wang Guoqing Zhang Lijun Wang Shenxiang Jia Jingsheng Cui Lishan Sinopec(Beijing)Research Institute of Chemical Industry Co. Ltd.Beijing 100013China Departments of Materials Science and Engineering China University of PetroleumBeijing 102249China

anti-coking oxide films were prepared on a 25Cr35Ni and 35Cr45Ni alloy surface under the low oxygen partialpressure atmosphere of a H2-H2O mixture. The composition and phase structure of the oxide films were analyzed by energydispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The anti-cokingperformance of a mini tube made of a HP40 (25Cr35Ni) alloy was evaluated on a bench scale pyrolysis and coking test *** results showed that the surface Fe and Ni content decreased after the oxidation of the two alloys in a low oxygen partialpressure atmosphere. The oxide films were mainly composed of MnCr_(2)O_(4) and Cr_(2)O_(3). The average mass of coke in the minitube with oxide film decreased by 87% relative to that of a tube without an oxide film when the cracking temperature was 900℃. The ethylene, propylene, and butadiene yields in the pyrolysis tests were almost the same for the mini tubes withand without an oxide film. The oxide film on the alloy surface effectively inhibited catalytic filamentous coke *** industrial test showed that the run length of the cracking furnace with the in-situ coating technology was significantlyextended.

关键词： Fe-Cr-Ni alloy low oxygen partial pressure oxide film anti-coking ethylene cracking furnace in-situ coating

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Rod-shaped porous alumina-supported Cr_2O_3 catalyst with low acidity for propane dehydrogenation

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Chinese Journal of Catalysis 2019年第2期40卷 184-191页

作者： Xin-Qian Gao Wen-Duo Lu Shou-Zhao Hu Wen-Cui Li An-Hui Lu State Key Laboratory of Fine Chemicals School of Chemical EngineeringDalian University of TechnologyDalian 116024LiaoningCh

Direct catalytic propane dehydrogenation(PDH)to obtain propylene is a more economical and environmentally friendly route for propylene *** particular,alumina-supported Cr2O3 catalysts can have better potential applications if the acidic properties could be ***,a series of rod-shaped porous alumina were prepared through a hydrothermal route,followed by *** was found that the acidity of the synthesized alumina was generally lower than that of the commercial alumina and could be adjusted well by varying the calcination *** alumina materials were used as supports for active Cr2O3,and the obtained catalysts could enhance the resistance to coke formation associated with similar activity in PDH reaction compared to the commercial *** amount of coke deposited on a self-made catalyst(Cr-Al-800)was 3.6%,which was much lower than that deposited on the reference catalyst(15.7%).The lower acidity of the catalyst inhibited the side reactions and coke formation during the PDH process,which was beneficial for its high activity and superior anti-coking properties.

关键词： Alumina Acidity Calcination Chromium anti-coking

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