520
Not only SAPO-34 but SAPO-5 has also been explored for CO 2 conversion to
fuels. Zhu et al. [105] prepared 2-dimensional SAPO-5 nanosheets (3.0 nm in
thickness) and applied for photocatalytic reduction of CO 2 into CH 4 . The nanosheets
showed high CO 2 absorption capacity of 12.9 cm
3
g
−1
with 8.6 μLg
−1
h
−1
as rate of
production of CH 4 . The research can be a milestone considering the high
global warming potential of CO 2 .
4 Conclusion
Silicoaluminophosphates analogous to zeolites have exhibited paramount applications in petrochemical industries. Their framework can be tailored to unique pore
apertures and acidity according to need. Three-dimensional small pores with 8-ring
channels having a pore diameter of 0.38 nm, in SAPO-34, serve excellent selectivity
for C 2 –C 4 alkenes in MTO reactions. The hydrocarbon pool mechanism coupled
with methyl benzene (MB route) describes the underlying chemistry in MTO reactions. The olefin conversion and lower olefin selectivity are chiefly controlled by the
combined effect of surface acidity and pore size diameter of the catalyst.
Consequently, selectivity for C 2 –C 4 alkenes follows the trend as small-pore
SAPO34 > medium-pore SAPO-11 > large-pore SAPO-5. Active metal loading
such as Mg, Zn, Ni, and hierarchical mesoporosity over these systems extends their
application in trans-esterification and platform chemical synthesis. The use of
bifunctional catalysts like ZrS/SAPO-34, In 2 O 3 -ZnZrO x /SAPO-34, etc., have been
successfully employed in selective hydrogenation of CO 2 to light olefins, serving
the dual purpose of checking greenhouse emission and clean fuel production.
SAPO-5 is mainly utilized in hydrocarbon isomerization reactions. The absence of
very strong acidity makes it good candidate in hydroisomerization reactions.
SAPO-11 on other hand possesses potential to be industrial catalyst, most of the
vegetable oil/ biomass conversions are successfully studied over it. They possess
optimum acidity and active sites for biomass conversion.
References
1. Wilson ST, Lok BM, Messina CA, Cannan TR, Flanigen EM (1982) Aluminophosphate
molecular sieves: a new class of microporous crystalline inorganic solids. J Am Chem Soc
104(4):1146–1147
2. Wilson ST, Lok BM, Flanigen EM (1982) US Patent 4,310,440
3. Messina CA, Lok BM, Flanigen EM (1985) US Patent 4,544,143
4. The increase in isomerization was due to large pores formed in SAPO-11(synthesized in
presence of both CTAB and F127) which resists cracking of dibranched products and reduces
probability of coke formation
5. Wilson ST, Flanigen EM (1989) Zeolite synthesis. In: Occelli MJ, Robson HE (eds) ACS
Symposium Series, vol 398. ACS, Washington, DC, pp 329–345
R. Yadav and A. K. Singh
Not only SAPO-34 but SAPO-5 has also been explored for CO 2 conversion to
fuels. Zhu et al. [105] prepared 2-dimensional SAPO-5 nanosheets (3.0 nm in
thickness) and applied for photocatalytic reduction of CO 2 into CH 4 . The nanosheets
showed high CO 2 absorption capacity of 12.9 cm
3
g
−1
with 8.6 μLg
−1
h
−1
as rate of
production of CH 4 . The research can be a milestone considering the high
global warming potential of CO 2 .
4 Conclusion
Silicoaluminophosphates analogous to zeolites have exhibited paramount applications in petrochemical industries. Their framework can be tailored to unique pore
apertures and acidity according to need. Three-dimensional small pores with 8-ring
channels having a pore diameter of 0.38 nm, in SAPO-34, serve excellent selectivity
for C 2 –C 4 alkenes in MTO reactions. The hydrocarbon pool mechanism coupled
with methyl benzene (MB route) describes the underlying chemistry in MTO reactions. The olefin conversion and lower olefin selectivity are chiefly controlled by the
combined effect of surface acidity and pore size diameter of the catalyst.
Consequently, selectivity for C 2 –C 4 alkenes follows the trend as small-pore
SAPO34 > medium-pore SAPO-11 > large-pore SAPO-5. Active metal loading
such as Mg, Zn, Ni, and hierarchical mesoporosity over these systems extends their
application in trans-esterification and platform chemical synthesis. The use of
bifunctional catalysts like ZrS/SAPO-34, In 2 O 3 -ZnZrO x /SAPO-34, etc., have been
successfully employed in selective hydrogenation of CO 2 to light olefins, serving
the dual purpose of checking greenhouse emission and clean fuel production.
SAPO-5 is mainly utilized in hydrocarbon isomerization reactions. The absence of
very strong acidity makes it good candidate in hydroisomerization reactions.
SAPO-11 on other hand possesses potential to be industrial catalyst, most of the
vegetable oil/ biomass conversions are successfully studied over it. They possess
optimum acidity and active sites for biomass conversion.
References
1. Wilson ST, Lok BM, Messina CA, Cannan TR, Flanigen EM (1982) Aluminophosphate
molecular sieves: a new class of microporous crystalline inorganic solids. J Am Chem Soc
104(4):1146–1147
2. Wilson ST, Lok BM, Flanigen EM (1982) US Patent 4,310,440
3. Messina CA, Lok BM, Flanigen EM (1985) US Patent 4,544,143
4. The increase in isomerization was due to large pores formed in SAPO-11(synthesized in
presence of both CTAB and F127) which resists cracking of dibranched products and reduces
probability of coke formation
5. Wilson ST, Flanigen EM (1989) Zeolite synthesis. In: Occelli MJ, Robson HE (eds) ACS
Symposium Series, vol 398. ACS, Washington, DC, pp 329–345
R. Yadav and A. K. Singh