Coke Removal from a Deactivated Industrial Diesel Hydrogenation Catalyst by Tetralin at 300-400 oC
Coke Removal from a Deactivated Industrial Diesel Hydrogenation Catalyst by Tetralin at 300-400 oC
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在 300-400 oC 下使用四氢化萘去除失活工业柴油加氢催化剂中的焦炭
DOI：
10.1021/acs.energyfuels.8b03983
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通讯作者：
Hong Nie
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作者：
Xinge Shi;Qingya Liu;Zhenyu Liu;Lei Shi;Wei Han;Mingfeng Li;Le Zhang;Hong Nie
加氢精制催化剂积炭是导致催化剂失活的主要原因之一。与非现场焦炭去除相比，现场焦炭去除是有利的。本文研究了四氢萘（THN）处理失活的工业柴油加氢Mo-Co-Ni/W-Al催化剂，在与操作条件相似的条件下，300-400 °C无H2。结果表明，Mo硫化物中心上的积炭（占积炭总量的19-23%）可在3 min内完全除去，使催化剂活性完全恢复。支架上的焦炭无法清除。结合程序升温氧化、扫描电镜、能谱分析和电子自旋共振等分析手段，探讨了THN中H自由基被Mo硫化物活化和H自由基对焦炭的加氢作用机理。除焦的最低要求是在340 °C下持续3分钟。THN的副反应在更高的温度和更长的处理时间下是显著的。Mo硫化物位点上的焦炭的自由基浓度类似于褐煤的自由基浓度，并且是催化剂载体上的焦炭的约10倍。
Coke deposition on hydrotreating catalysts is one of the main reasons of deactivation. In situ coke removal is advantageous compared to the off-site coke removal. This paper studies tetralin (THN) treatment of a deactivated industrial diesel hydrogenation Mo–Co–Ni/W–Al catalyst at conditions similar to the operation, 300–400 °C without H2. The results show that the coke on the Mo sulfide sites, corresponding to 19–23% total coke, can be removed in 3 min to fully restore the catalyst’s activity. The coke on the support cannot be removed. On the basis of the temperature-programmed oxidation, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electron spin resonance, coke removal mechanism is discussed, which includes activation of H radicals in THN by the Mo sulfide sites and hydrogenation of coke by the H radicals. The minimal requirement for the coke removal is 340 °C for 3 min. The side reactions of THN are significant at higher temperatures and longer treatment times. The radical concentration of coke on the Mo sulfide sites is similar to that of lignites and is approximately 10 times the coke on the catalyst support.