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A study on middle distillate hydrotreatment zeolite catalysts containing Pt /Pd and /or
Ni was performed . The effect of the addition of the corresponding CoMo , CoMoPd ,
CoMoPtPd and CoMoNi in PdNiPt -zeolite , Pt -zeolite , Ni -zeolite , and PdPt -zeolite was
studied . The catalysts were characterized physically and chemically by methods and
techniques such as Brunauer -Emmett -Teller (BET ) , Barret -Joyner -Hallenda (BJH ) , and
neutron activation analysis . The structures of the Ni and Pt containing zeolite were
studied by X -ray Photoelectron Spectroscopy (XPS ) .
An experimental apparatus was constructed to investigate the activity of the
experimental catalysts . The catalysts activity measured in terms of conversion of
dibenzothiophene (DBT ) , substituted dibenzothiophenes (sDBT ) and phenanthrene as
well as molar -averaged conversion was evaluated in a continuous flow Robinson
Mahoney reactor with stationary basket in the hydrodesulfurization and hydrogenation
of heavy gas oil which contains sulphur refractory compounds such as 4 -
methyldibenzotiophene (4 -MDBT ) and 4 ,6 - dimethyldibenzothiophene (4 ,6 -DMDBT ) .
DBT , 4 -MDBT , 3 -MDBT , 1 -EDBT , 3 -EDBT , 4 ,6 -DMDBT , 3 ,6 -DMDBT , 2 ,8 -
DMDBT and 4 -methylnaphtho[2 ,1 -b]thiophene were selected to calculate the molaraveraged
conversion .
The conversions of the sulfur containing compounds and phenanthrene were
determined as a function of the operating variables : space time (W /Fo
DBT ) , temperature ,
H2 /HC mol ratio and pressure . The Conversions of DBT and 4 ,6 -DMDBT into their reaction products such as Biphenyl (BPH ) , Cyclohexylbenzene (CHB ) , Bicyclohexyl
(BCH ) and 3 ,4 -Dimethylbiyphenyl (3 ,4 -DMBPH ) were determined only as a function of
space time in the interval of 4000 -6000 kgcath /kmol .
The results of this work showed that Pt -HY and PdPt -HY are good noble metals
catalysts for the hydrodesulfurization of heavy gas oil . Moreover , this study showed that
CoMoPd /Pt -HY and CoMoNi /PdPt -HY catalysts are good candidates for deep HDS and
hydrogenation of heavy gas oil . It was found that the conversions of sulfur compounds
were higher than the conversions provided by the conventional CoMo /Al2O3 catalyst .
Also higher hydrogenation of phenanthrene was observed . Deactivation of the catalysts
was not observed during the operation .
Finally , the study not only contributed to define the technical bases for the
preparation of the noble metal catalysts for hydrodesulfurization of heavy gas oil at pilot
scale , but also provided technical information for developing the kinetic modeling of the
hydrodesulfurization of heavy gas oil with the noble metal catalysts . |
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