515
catalyst showed >90% conversion of 1-octene; however, the product distribution
remained same irrespective of the reaction temperature.
3.1.4 Comparison of Activity Between SAPO-5 and SAPO-11
The catalytic activities of medium-pore and large-pore SAPOs for hydrocarbons
conversion have been compared (see Table 3); the following section discusses a few
of them. Höchtl et al. [68] studied 1-pentene isomerization of 1-pentene over AELand AFI-type structure (for both SAPO and CoAPO). The acidic strengths followed
the order SAPO-5 < CoAPO-5 < SAPO-11 < CoAPO-11. The equilibrium distribution between the linear and branched products was achieved except at lower temperatures. The SAPO-5 showed higher deactivation due to coking on stronger
acidic sites.
The hydroisomerization and hydrocracking of n-Octane was studied by Campelo
et al. [69] using 0.5 wt% Pt/SAPO-5 and 0.5 wt% Pt/SAPO-11. Both the catalysts
showed good activity in n-octane conversion; the aromatic products obtained over
SAPO-5 catalyst were p- and m-xylene which are expected to be formed from cyclization of C 8 -isoalkanes. However, over Pt/SAPO-11 ethylbenzene and o-xylene
were reported as dominant products which are formed by direct cyclization of
n-octane. The selectivity of the products varies due to steric hindrance showed by
SAPO-11. The same group studied the hydroisomerization and hydrocracking of
n-hexane [70]. The authors reported Pt/SAPO-5 to be more active with high selectivity toward iso-hexane which might be due to its optimum pore and acidity.
Wang et al. [71] studied the shape-selective properties of SAPO-11 and
SAPO-5 in methylation of naphthalene using methanol (methylation agent) and
mesitylene (solvent). The acidity studies showed that the SAPO-5 possessed only
weak acidic sites whereas SAPO-11 possessed both weak acidic sites as well as
moderate acidic sites. SAPO-11 and SAPO-5 showed conversion of 55.2 and 26.1%,
Table 3 Reaction conditions used for hydrocarbon conversion over SAPO-11 and SAPO-5
Reactant
Temperature
(K)
WHSV
(h
−1 )
Metal
Others
References
1-pentene
523–823
–
–
P = 0.1 MPa
Höchtl et al.
[68]
n-octene
573–708
–
0.5 wt% Pt
P = 3–5 bar
H 2 = 25 mL/min
Campelo et al.
[69]
n-hexane
573–708
–
0.5 wt% Pt
P = 3–5 bar
H 2 = 25 mL/min
Campelo et al.
[70]
Naphthalene:
methanol:
mesitylene (1:
5: 3.5)
623
0.19
–
–
Wang et al. [71]
n-hexane
498–648
–
0.2 wt% Pt
and Ni (0, 0.2,
0.4 and
0.6 wt%)
LHSV = 1.0 h
−1
Eswaramoorthi
et al. [72]
Recent Developments on Clean Fuels over SAPO-Type Catalysts
catalyst showed >90% conversion of 1-octene; however, the product distribution
remained same irrespective of the reaction temperature.
3.1.4 Comparison of Activity Between SAPO-5 and SAPO-11
The catalytic activities of medium-pore and large-pore SAPOs for hydrocarbons
conversion have been compared (see Table 3); the following section discusses a few
of them. Höchtl et al. [68] studied 1-pentene isomerization of 1-pentene over AELand AFI-type structure (for both SAPO and CoAPO). The acidic strengths followed
the order SAPO-5 < CoAPO-5 < SAPO-11 < CoAPO-11. The equilibrium distribution between the linear and branched products was achieved except at lower temperatures. The SAPO-5 showed higher deactivation due to coking on stronger
acidic sites.
The hydroisomerization and hydrocracking of n-Octane was studied by Campelo
et al. [69] using 0.5 wt% Pt/SAPO-5 and 0.5 wt% Pt/SAPO-11. Both the catalysts
showed good activity in n-octane conversion; the aromatic products obtained over
SAPO-5 catalyst were p- and m-xylene which are expected to be formed from cyclization of C 8 -isoalkanes. However, over Pt/SAPO-11 ethylbenzene and o-xylene
were reported as dominant products which are formed by direct cyclization of
n-octane. The selectivity of the products varies due to steric hindrance showed by
SAPO-11. The same group studied the hydroisomerization and hydrocracking of
n-hexane [70]. The authors reported Pt/SAPO-5 to be more active with high selectivity toward iso-hexane which might be due to its optimum pore and acidity.
Wang et al. [71] studied the shape-selective properties of SAPO-11 and
SAPO-5 in methylation of naphthalene using methanol (methylation agent) and
mesitylene (solvent). The acidity studies showed that the SAPO-5 possessed only
weak acidic sites whereas SAPO-11 possessed both weak acidic sites as well as
moderate acidic sites. SAPO-11 and SAPO-5 showed conversion of 55.2 and 26.1%,
Table 3 Reaction conditions used for hydrocarbon conversion over SAPO-11 and SAPO-5
Reactant
Temperature
(K)
WHSV
(h
−1 )
Metal
Others
References
1-pentene
523–823
–
–
P = 0.1 MPa
Höchtl et al.
[68]
n-octene
573–708
–
0.5 wt% Pt
P = 3–5 bar
H 2 = 25 mL/min
Campelo et al.
[69]
n-hexane
573–708
–
0.5 wt% Pt
P = 3–5 bar
H 2 = 25 mL/min
Campelo et al.
[70]
Naphthalene:
methanol:
mesitylene (1:
5: 3.5)
623
0.19
–
–
Wang et al. [71]
n-hexane
498–648
–
0.2 wt% Pt
and Ni (0, 0.2,
0.4 and
0.6 wt%)
LHSV = 1.0 h
−1
Eswaramoorthi
et al. [72]
Recent Developments on Clean Fuels over SAPO-Type Catalysts