系统研究了丙烷裂解过程中纯镍表面的结焦形貌及其影响因 素.结果表明，纯镍表面的沉积焦炭有三种形貌，分别为纤维状、颗粒状和膜状.纤维状焦 炭在800℃左右形成，需要基底金属镍的参与，预氧化后的镍表面显著加剧这种焦炭的沉积 .提高结焦温度或延长结焦时间，结焦机制发生转变，焦炭形貌也逐渐转变为颗粒状.颗粒 状焦炭形成于气相反应，与基底金属镍无关.膜状焦炭形成于结焦初期，溶解/析出机制及 表面直接形核、生长机制均对其形成有贡献.抑制纤维状焦炭的形成有益于减轻镍表面总的 结焦程度.
Surface coking morphology of pure nickel and its correlative factors w ere investigated systematically.Results reveal that the coke deposited on surf ace of pure nickel includes the filamentary coke,the particlelike coke,and th e filmlike coke.Deposition of the filamentary coke happens at approximate 800 ℃ and is closely dependent on the nickel substrate.Preoxidation markedly aggr avates the deposition of the filamentary coke on surface of pure nickel.Either raising the coking temperature or prolonging the coking time results in change o f the coking mechanism,and the deposited coke tends to show a particlelike mor phology.Since the particlelike coke is derived from a series of gasphase rea ctions,it bears no relation to the nickel substrate naturally.The filmlike cok e is only deposited at the initial coking stage.Both the dissolution/precipitat ion mechanism and the direct nucleation/growth mechanism may make a contribution to development of the filmlike coke.Restraining the formation of the filament ary coke can be beneficial to alleviate the totally coking degree on the nickel surface.
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