28
CoMgMoAl-layered double hydroxides with varied Co and Mo contents were
also studied for the selective HDS of model compound thiophene in the presence of
cyclohexene as an olefinic compound and n-heptane. The LDHs showed higher
selectivity for HDS in comparison with industrial catalysts. Co-Mo catalysts prepared using Zn-Al-layered double hydroxides were also reported for the selective
HDS of FCC gasoline [94]. Coelho et al. [95] prepared unsupported heptamolybdateCoMgAl hydrotalcites from terephthalate precursors and reported higher HDS
selectivity compared to conventional CoMo/Al 2 O 3 catalysts.
7 Conclusions
Research in hydrotreating/hydrodesulfurization catalysis has advanced multifold
after the introduction of stringent fuel specifications, especially with respect to sulfur content in both gasoline and diesel. Catalysis scientists have overcome the challenges and are able to come up with highly active catalysts for producing ultralow
sulfur diesel due to advancements in catalyst characterization techniques, preparation strategies, active phase dispersion methods, tuning the support structure, and
understanding the micro- and macrolevel happenings on the catalyst. Catalyst
advancements along with simultaneous process improvements helped the refiners to
achieve their environmental targets in meeting the fuel specifications. Catalysis science in hydrotreating is still advancing in terms of new mixed supports, novel preparation methods for better dispersion of active components, use of unsupported
catalysts, additives for reducing MSI, etc. All the recent research advances are
aimed at improving the activity of the current generation catalysts while also simultaneously enhancing the selectivity for removal of sulfur from refractory aromatic
sulfur species and stability of the catalyst. It is of paramount importance to increase
the yields of desired hydrocarbons by tuning the catalyst acidity. There is interdependence of different catalytic functions, which needs to be considered in order to
reduce sulfur content and increase hydrocarbon yields. There is a balance in activity
that is needed for any successful catalyst. The present chapter discussed the current
advancements in the nature of active phase and catalyst support, specifically aimed
to achieve ultralow sulfur content in petroleum fuels.
Acknowledgments The authors thank the management of Hindustan Petroleum Corporation
Limited, Green R&D Center, Bengaluru, for allowing them to publish this chapter.
References
1. Zhou W, Wei Q, Zhou Y, Liu M, Ding S, Yang Q (2018a) Hydrodesulfurization of
4,6- dimethyldibenzothiophene over NiMo sulfide catalysts supported on meso-microporous Y
zeolite with different mesopore sizes. Appl Catal B Environ 238:212–224
G. Valavarasu and B. Ramachandrarao
CoMgMoAl-layered double hydroxides with varied Co and Mo contents were
also studied for the selective HDS of model compound thiophene in the presence of
cyclohexene as an olefinic compound and n-heptane. The LDHs showed higher
selectivity for HDS in comparison with industrial catalysts. Co-Mo catalysts prepared using Zn-Al-layered double hydroxides were also reported for the selective
HDS of FCC gasoline [94]. Coelho et al. [95] prepared unsupported heptamolybdateCoMgAl hydrotalcites from terephthalate precursors and reported higher HDS
selectivity compared to conventional CoMo/Al 2 O 3 catalysts.
7 Conclusions
Research in hydrotreating/hydrodesulfurization catalysis has advanced multifold
after the introduction of stringent fuel specifications, especially with respect to sulfur content in both gasoline and diesel. Catalysis scientists have overcome the challenges and are able to come up with highly active catalysts for producing ultralow
sulfur diesel due to advancements in catalyst characterization techniques, preparation strategies, active phase dispersion methods, tuning the support structure, and
understanding the micro- and macrolevel happenings on the catalyst. Catalyst
advancements along with simultaneous process improvements helped the refiners to
achieve their environmental targets in meeting the fuel specifications. Catalysis science in hydrotreating is still advancing in terms of new mixed supports, novel preparation methods for better dispersion of active components, use of unsupported
catalysts, additives for reducing MSI, etc. All the recent research advances are
aimed at improving the activity of the current generation catalysts while also simultaneously enhancing the selectivity for removal of sulfur from refractory aromatic
sulfur species and stability of the catalyst. It is of paramount importance to increase
the yields of desired hydrocarbons by tuning the catalyst acidity. There is interdependence of different catalytic functions, which needs to be considered in order to
reduce sulfur content and increase hydrocarbon yields. There is a balance in activity
that is needed for any successful catalyst. The present chapter discussed the current
advancements in the nature of active phase and catalyst support, specifically aimed
to achieve ultralow sulfur content in petroleum fuels.
Acknowledgments The authors thank the management of Hindustan Petroleum Corporation
Limited, Green R&D Center, Bengaluru, for allowing them to publish this chapter.
References
1. Zhou W, Wei Q, Zhou Y, Liu M, Ding S, Yang Q (2018a) Hydrodesulfurization of
4,6- dimethyldibenzothiophene over NiMo sulfide catalysts supported on meso-microporous Y
zeolite with different mesopore sizes. Appl Catal B Environ 238:212–224
G. Valavarasu and B. Ramachandrarao