Structure and composition of hard coke deposited on industrial fluid catalytic cracking catalysts by solid state 13C nuclear magnetic resonance

CATEGORY: COKE
Applied Catalysis A: General, Volume 466, 10 September 2013, Pages 123–130
Structure and composition of hard coke deposited on industrial fluid catalytic cracking catalysts by solid state ¹³C nuclear magnetic resonance
Babita Behera, Piyush Gupta, Siddharth S. Ray
CSIR-Indian Institute of Petroleum, Dehradun 248005, India
Abstract
Reports results of a study of carbonaceous deposits (hard coke) using several solid state ¹³C nuclear magnetic resonance (NMR) techniques after demineralization of the spent and regenerated fluid catalytic cracking (FCC) catalysts obtained from Indian refineries. A variety of structural parameters, including aromaticity, H/C ratio, fraction of protonated f_a^P and non-protonated f_a^NP aromatic carbons, number of pericondensed rings per average molecule (N_peri), and aromatic condensation index (γ_ar) were derived from the NMR data.
Researchers rationalized observations of thirty-two and thirty-nine aromatic rings in coke from regenerated catalysts and five and nineteen rings in coke from spent catalysts using several parameters, including feed, temperature and process conditions of FCC reactor on the basis of condensation. They noted that the coke was more condensed in regenerated catalysts compared to spent catalysts.  This indicates that the temperature has a marked effect in the evolution of coke structure. Feeds and other process conditions, on the other hand, govern the nature and composition of coke.
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