Fluid Catalytic
Cracking Study of Coker Gas Oil: Effects
of Processing Parameters on Sulfur and Nitrogen Distributions
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Abstract
To
investigate the effects of operating conditions and the catalyst
activity on the transfer regularity of sulfur and nitrogen during
the cracking process of coker gas oil (CGO), the CGO was catalytically
cracked in a pilot-scale riser fluid catalytic cracking (FCC) apparatus
at different test environments. Then the cracked liquid products were
analyzed for sulfur and nitrogen distributions with boiling point,
from which the sulfur and nitrogen concentrations of gasoline, light
cycle oil (LCO), and heavy cycle oil (HCO) fractions were determined.
The sulfur and nitrogen compounds in each product cut, and their possible
reaction pathways were reviewed and discussed. The results show that
sulfur-containing species are easier to crack but more difficult to
be removed from the liquid product, while nitrogen compounds are easier
to form coke, then be removed from the liquid product. The sulfur
distribution of CGO is different from that of conventional feedstocks.
Different processing parameters can significantly affect the sulfur
and nitrogen distribution yields and concentrations in liquid products.
Increasing the reaction temperature and the catalyst-to-oil ratio
as well as shortening the residence time cannot only increase the
light oil yield but also improve the product quality and reduce the
SO<sub><i>x</i></sub> and NO<sub><i>x</i></sub> emissions in the regenerator