1
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J. Bai et al. / Journal of Catalysis 287 (2012) 161–169
Scheme 1. Pseudo-first-order rate constants (in mol/g min) in the reaction network of the HDS of DBT over MoP at 340 °C and 4 MPa in the absence and presence (in
parentheses) of 0.25 kPa Pi.
DDS route. The difference in the kinetic behavior between MoP and
the Mo-based sulfides suggests that the nature of the sulfided MoP
surface should be different from those of the molybdenum sulfides.
Our results confirm that Pi is a strong poison in the HDS of DBT
over MoP. The rate constants of the HYD and DDS pathways were
about fourfold lower and twofold lower, respectively, in the pres-
ence than in the absence of Pi. This indicates that Pi inhibits both
pathways, but the HYD pathway to a greater extent than the DDS
pathway. Pi also strongly suppressed the desulfurization of TH-
DBT and HH-DBT. However, the reactions between TH-DBT and
HH-DBT, especially the dehydrogenation of HH-DBT to TH-DBT,
were less affected by Pi. Regardless of this fast interconversion,
the HDS of DBT, TH-DBT, and HH-DBT were strongly inhibited by
Pi, hydrogenation to a greater extent than desulfurization. This
proves that the nitrogen-containing compound adsorbed more
strongly than DBT and its partially hydrogenated intermediates
on the catalytic sites and adsorbed on both the desulfurization
and (de)hydrogenation sites. The degree of inhibition of Pi on the
desulfurization of DBT, THDBT, and HHDBT decreased in the order
of HHDBT > THDBT > DBT, which can be attributed to the different
strengths of adsorption of these molecules on the catalytic sites
compared with the nitrogen-containing compound [18].
Institute of Petroleum and Petrochemicals, SINOPEC) for assistance
in XPS measurements.
Appendix A. Supplementary material
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