Structural characterisation of catalytic coke by solid-state C-13-NMR spectroscopy
Structural characterisation of catalytic coke by solid-state C-13-NMR spectroscopy
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DOI：
10.1016/s0920-5861(97)00021-7
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发表时间：
1997-08-15
期刊：
影响因子：
5.3
通讯作者：
Andresen, JM
中科院分区：
文献类型：
--
作者：
Snape, CE;McGhee, BJ;Andresen, JM
本文综述了近年来用固态C-13-MMR表征流化催化裂化（FCC）和加氢处理催化剂上积炭的一些研究成果，并介绍了用FCC催化剂脱矿提供焦炭浓缩物进行分析所获得的定量结构信息。研究的失活催化剂仅含有约。1%（w/w）的碳，并获得从炼油厂装置操作与重质进料和从实验室流化床试验与正十六烷。至于其他含碳材料，使用低场场强结合单脉冲激发（SPE或布洛赫衰减）技术，使大多数的碳被检测到，因此，NMR不可见的石墨层不被认为是焦炭的主要结构特征。尽管汽提催化剂产生高芳族焦炭（芳香度>0.95），即使对于正十六烷，原料组成的差异仍然反映在所得焦炭的结构中，其中源自正十六烷的那些焦炭比源自重质进料的那些焦炭含有更少的稠合芳族核。
After reviewing some recent studies on the characterisation of coke deposits on fluid catalytic cracking (FCC) and hydroprocessing catalysts by solid state C-13-MMR, the quantitative structural information that has been obtained through the use of demineralisation of FCC catalysts to provide coke concentrates for analysis will be described. The deactivated catalysts investigated contain only approx. 1% (w/w) carbon and were obtained both from refinery units operating with heavy feeds and from laboratory fluidised-bed tests with n-hexadecane. As for other carbonaceous materials, the use of a low-field field strength in conjunction with the single pulse excitation (SPE or Bloch decay) technique has enabled most of the carbon to be detected and, therefore, NMR-invisible graphitic layers are not thought to be major structural features of the cokes. Although stripping the catalysts gives rise to highly aromatic cokes (aromaticity>0.95), even for n-hexadecane, differences in feedstock composition are still reflected in the structure of the resultant cokes with those derived from n-hexadecane containing less condensed aromatic nuclei than those from heavy feeds.