92
uses catalyst additives. Moreover, catalyst additive-based sulfur reduction in FCC
gasoline is economically efficient and does not require much capital expenditure.
Typical full-range FCC gasoline contains sulfur in the form of mercaptans, sulfides, disulfides, thiophenes, and benzothiophenes. Mercaptans, sulfides, and disulfides are present in the lighter fraction of gasoline pool and can easily be cracked in
the presence of a catalyst to liberate sulfur as H 2 S. The middle fraction of gasoline
mostly contains tetrahydrothiophene, thiophenes, and alkyl thiophenes. Although
tetrahydrothiophene gets cracked in the presence of Lewis acidic catalyst, reduction
levels for thiophenes typically vary from 30% to 40%. The most difficult species to
remove are the benzothiophenes found in the heaviest portion of the gasoline [75].
Gasoline sulfur reduction (GSR) additive can be added separately from the host
FCC catalyst via a second hopper, and their effects are observed fairly quickly. Fluid
catalytic cracking additives reduce sulfur in gasoline by the selective cracking of
sulfur compounds into H 2 S in situ in the FCC riser. Grace Davison, Albermarle, and
Interact have FCC catalyst additive technologies specifically developed to catalytically reduce sulfur-containing compounds in the gasoline boiling range [79].
Grace Davison’s sulfur reduction additives, GSR-1 and D-Prism, commercialized in 1995 and 2001, respectively, are most effective in reducing sulfur species in
light naphtha, and a typical sulfur reduction of 15–25% is achieved in the presence
of 10 wt% of the additive. Patents assigned to Grace on FCC additives disclosed
Lewis acid component (Ni, Cu, Zn, Ag, Cd, In, Sn, Hg, Ti) supported on alumina.
Zhao et al. [78] reported a composition containing vanadium oxalate supported on
alumina for gasoline sulfur reduction and sulfur in gasoline (without benzothiophene) dropped by 55–65% as compared to the base FCC catalyst. Most of the
patents assigned to Grace and ExxonMobil are mostly about additives with metal
components containing V and Zn [80–82].
Albemarle reported 26% reduction in light naphtha sulfur on the commercial
performance of GSR additive, Resolve 750 at 20% of overall catalyst inventory.
Myrstad et al. [79] described a composition for reducing sulfur content in hydrocarbons, wherein the additive comprised a hydrotalcite material that had been impregnated with a Lewis acid preferably Zn, Cu, Ni, Co, Fe, and Mn. In 1999, Andersson
[81] investigated several groups of additives with different compositions to reduce
sulfur in gasoline by depositing various metals and metal oxides on different supports. The sulphur reduction ability of different compositions follows Zn/hydrotalcite > ZrO/alumina > Zn/titania > Mn/alumina. Shan et al. [81] showed that an
additive comprising USY/ZnO/alumina has an excellent sulfur removal effect, and
~50% reduction in gasoline sulfur was achieved with 30% of the additive with only
a little change in product distribution. In a very recent commercial use at BPCL
Mumbai Refinery, GSR catalyst developed by BPCL showed ~33% reduction in
gasoline sulfur in the presence of 10% of overall catalyst inventory. The catalyst
composition reuses the FCC equilibrium catalyst for the novel GSR additive preparation. Various metal oxides on FCC equilibrium catalyst were found to be effective
catalysts in reducing sulfur from fuel streams [76, 77].
A. R. Khande et al.
uses catalyst additives. Moreover, catalyst additive-based sulfur reduction in FCC
gasoline is economically efficient and does not require much capital expenditure.
Typical full-range FCC gasoline contains sulfur in the form of mercaptans, sulfides, disulfides, thiophenes, and benzothiophenes. Mercaptans, sulfides, and disulfides are present in the lighter fraction of gasoline pool and can easily be cracked in
the presence of a catalyst to liberate sulfur as H 2 S. The middle fraction of gasoline
mostly contains tetrahydrothiophene, thiophenes, and alkyl thiophenes. Although
tetrahydrothiophene gets cracked in the presence of Lewis acidic catalyst, reduction
levels for thiophenes typically vary from 30% to 40%. The most difficult species to
remove are the benzothiophenes found in the heaviest portion of the gasoline [75].
Gasoline sulfur reduction (GSR) additive can be added separately from the host
FCC catalyst via a second hopper, and their effects are observed fairly quickly. Fluid
catalytic cracking additives reduce sulfur in gasoline by the selective cracking of
sulfur compounds into H 2 S in situ in the FCC riser. Grace Davison, Albermarle, and
Interact have FCC catalyst additive technologies specifically developed to catalytically reduce sulfur-containing compounds in the gasoline boiling range [79].
Grace Davison’s sulfur reduction additives, GSR-1 and D-Prism, commercialized in 1995 and 2001, respectively, are most effective in reducing sulfur species in
light naphtha, and a typical sulfur reduction of 15–25% is achieved in the presence
of 10 wt% of the additive. Patents assigned to Grace on FCC additives disclosed
Lewis acid component (Ni, Cu, Zn, Ag, Cd, In, Sn, Hg, Ti) supported on alumina.
Zhao et al. [78] reported a composition containing vanadium oxalate supported on
alumina for gasoline sulfur reduction and sulfur in gasoline (without benzothiophene) dropped by 55–65% as compared to the base FCC catalyst. Most of the
patents assigned to Grace and ExxonMobil are mostly about additives with metal
components containing V and Zn [80–82].
Albemarle reported 26% reduction in light naphtha sulfur on the commercial
performance of GSR additive, Resolve 750 at 20% of overall catalyst inventory.
Myrstad et al. [79] described a composition for reducing sulfur content in hydrocarbons, wherein the additive comprised a hydrotalcite material that had been impregnated with a Lewis acid preferably Zn, Cu, Ni, Co, Fe, and Mn. In 1999, Andersson
[81] investigated several groups of additives with different compositions to reduce
sulfur in gasoline by depositing various metals and metal oxides on different supports. The sulphur reduction ability of different compositions follows Zn/hydrotalcite > ZrO/alumina > Zn/titania > Mn/alumina. Shan et al. [81] showed that an
additive comprising USY/ZnO/alumina has an excellent sulfur removal effect, and
~50% reduction in gasoline sulfur was achieved with 30% of the additive with only
a little change in product distribution. In a very recent commercial use at BPCL
Mumbai Refinery, GSR catalyst developed by BPCL showed ~33% reduction in
gasoline sulfur in the presence of 10% of overall catalyst inventory. The catalyst
composition reuses the FCC equilibrium catalyst for the novel GSR additive preparation. Various metal oxides on FCC equilibrium catalyst were found to be effective
catalysts in reducing sulfur from fuel streams [76, 77].
A. R. Khande et al.