Characterization of Basic Nitrogen Aromatic Species Obtained during Fluid Catalytic Cracking by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

摘要

The basic-nitrogen aromatic compounds in feedstocks and liquid products from the micro-reactor and soluble components of coke obtained during fluid catalytic cracking (FCC) process were analyzed by the micro-electrospray ionization (ESI) 9.4T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with an average mass resolving power of 300 000 at a mass range of 100-1 200. The analytical results revealed that the coker gas oil (CGO) contained a higher abundance of basic-nitrogen aromatic compounds with the type of -5N to -9N compared with those in deasphalted oil (DAO) and mixed FCC feedstock. After catalytic cracking, the abundance of lowly condensed basic-nitrogen aromatic compounds was much less than those of highly condensed aromatics in the liquid products, with the carbon number mainly ranging from 6 to 25 and the average carbon number of the side-chains equating to 1-5. On the contrary, with respect to the soluble components of coke, the abundance of lowly condensed basic-nitrogen aromatic compounds was more than those of highly condensed aromatics, and the carbon number ranged from 12 to 30, which was much smaller than that of the mixed FCC feedstock but slightly larger than that of the cracked liquid products. These results have provided some fundamental information on FCC process.