511
islands. 0.5 wt% Pt loaded samples were utilized for isomerization of n-hexane,
n-octane, and n-hexadecane over a temperature range of 548–648 K in presence of
H 2 . The hydroconversion follows the order Pt-SAPO-31(na) > PtSAPO- 31(a) > Pt-SAPO-11(na) > Pt-SAPO-11(a). A slight high activity of SAPO-31
was reported which might be due to the large pore of SAPO-31. Among all the
hydrocarbons n-hexadecane showed highest conversion on all catalysts over the
entire temperature range and n-hexane showed the least. Also the authors reported
more reactions at the pore mouth and the external surface in the case of SAPO-31
compared to SAPO-11. Wu et al. [55] varied the synthetic conditions (including
templates) of SAPO-11 and studied for dehydration of ethanol to ethylene. The
synthesized SAPO-11 was compared with commercial SAPO-11. Synthesized
SAPO-11 showed 99% conversion of ethanol to ethylene at 280 °C, whereas the
commercial catalyst needed 300 °C to reach the conversion. The selectivity of products in both the cases remained same. The study showed that tuning the catalyst
synthesis conditions and precursors selection can have a huge impact on its catalytic
activity. Tian et al. [48] prepared Ni phosphide-supported SAPO-11 and utilize it for
hydroisomerization of n-dodecane. During the preparation of catalysts, different
Ni/P ratios were used with 3 wt% of nominal Ni. The catalytic activity of NiP/
SAPO-11was reported higher compared to Ni/SAPO-11 and SAPO-11. Maximum
selectivity of iso-dodecane was reported with Ni/P ratio of 1; however with increase
in Ni/P ratio, increase in conversion was reported. The high conversion and selectivity was reported on the catalyst with medium acidic sites; the synergic effect of
acidic sites and Ni sites resulted in high selectivity of the product. At 623 K, 2%NiP
(1/1)/SAPO-11 and 3%NiP (1/1)/SAPO-11 are reported to yield above 70% and
65%, respectively. The conversion showed increasing trend with rise in temperature
and WHSV (from 1.5 to 6.0 h
−1
) with lower selectivity toward iso-dodecane,
whereas H 2 pressure beyond 2.0 MPa was reported unfavorable to alkene intermediate formation.
Not only the synthesis medium, but also the template used in the synthesis can
alter catalyst properties. The change in template has an influence on Si distribution,
acidity as well as on crystallinity. Ping et al. [49] synthesized SAPO-11 using mixed
template of di-n-propylamine (DPA) and di-iso-propylamine (DIPA) by varying the
template content ratio of DPA/DIPA. Catalyst prepared with DPA/DIPA ratio of 1.5
and 0.36% Pt showed the highest number of acidic sites. When applied for ntetradecane isomerization, the catalyst with 1.5 template ratio showed higher conversion of 82% with 94.5% selectivity toward isomerized products at 593 K with
WHSV of 2.0 h
−1
. The higher conversion was reported due to uniform distribution
of Si which resulted in small silicon domains and high acidity.
Promoters on a metal-loaded catalyst play a positive role in catalysis by enhancing the synergistic effect between the metal sites and acidic sites of catalysts. Liu
et al. [56] studied the effect of Sn as a promotor on the Pt/SAPO-11 catalyst for
hydroconversion of n-dodecane. The conversion of 91.1% and 90.5% was reported
on Sn-Pt/SAPO-11 and Pt/SAPO-11, respectively. The conversion is almost similar
in both cases; however, an increase in 10% selectivity toward mono-branched products with a decrease in cracked products was reported. The increased Sn content
Recent Developments on Clean Fuels over SAPO-Type Catalysts
islands. 0.5 wt% Pt loaded samples were utilized for isomerization of n-hexane,
n-octane, and n-hexadecane over a temperature range of 548–648 K in presence of
H 2 . The hydroconversion follows the order Pt-SAPO-31(na) > PtSAPO- 31(a) > Pt-SAPO-11(na) > Pt-SAPO-11(a). A slight high activity of SAPO-31
was reported which might be due to the large pore of SAPO-31. Among all the
hydrocarbons n-hexadecane showed highest conversion on all catalysts over the
entire temperature range and n-hexane showed the least. Also the authors reported
more reactions at the pore mouth and the external surface in the case of SAPO-31
compared to SAPO-11. Wu et al. [55] varied the synthetic conditions (including
templates) of SAPO-11 and studied for dehydration of ethanol to ethylene. The
synthesized SAPO-11 was compared with commercial SAPO-11. Synthesized
SAPO-11 showed 99% conversion of ethanol to ethylene at 280 °C, whereas the
commercial catalyst needed 300 °C to reach the conversion. The selectivity of products in both the cases remained same. The study showed that tuning the catalyst
synthesis conditions and precursors selection can have a huge impact on its catalytic
activity. Tian et al. [48] prepared Ni phosphide-supported SAPO-11 and utilize it for
hydroisomerization of n-dodecane. During the preparation of catalysts, different
Ni/P ratios were used with 3 wt% of nominal Ni. The catalytic activity of NiP/
SAPO-11was reported higher compared to Ni/SAPO-11 and SAPO-11. Maximum
selectivity of iso-dodecane was reported with Ni/P ratio of 1; however with increase
in Ni/P ratio, increase in conversion was reported. The high conversion and selectivity was reported on the catalyst with medium acidic sites; the synergic effect of
acidic sites and Ni sites resulted in high selectivity of the product. At 623 K, 2%NiP
(1/1)/SAPO-11 and 3%NiP (1/1)/SAPO-11 are reported to yield above 70% and
65%, respectively. The conversion showed increasing trend with rise in temperature
and WHSV (from 1.5 to 6.0 h
−1
) with lower selectivity toward iso-dodecane,
whereas H 2 pressure beyond 2.0 MPa was reported unfavorable to alkene intermediate formation.
Not only the synthesis medium, but also the template used in the synthesis can
alter catalyst properties. The change in template has an influence on Si distribution,
acidity as well as on crystallinity. Ping et al. [49] synthesized SAPO-11 using mixed
template of di-n-propylamine (DPA) and di-iso-propylamine (DIPA) by varying the
template content ratio of DPA/DIPA. Catalyst prepared with DPA/DIPA ratio of 1.5
and 0.36% Pt showed the highest number of acidic sites. When applied for ntetradecane isomerization, the catalyst with 1.5 template ratio showed higher conversion of 82% with 94.5% selectivity toward isomerized products at 593 K with
WHSV of 2.0 h
−1
. The higher conversion was reported due to uniform distribution
of Si which resulted in small silicon domains and high acidity.
Promoters on a metal-loaded catalyst play a positive role in catalysis by enhancing the synergistic effect between the metal sites and acidic sites of catalysts. Liu
et al. [56] studied the effect of Sn as a promotor on the Pt/SAPO-11 catalyst for
hydroconversion of n-dodecane. The conversion of 91.1% and 90.5% was reported
on Sn-Pt/SAPO-11 and Pt/SAPO-11, respectively. The conversion is almost similar
in both cases; however, an increase in 10% selectivity toward mono-branched products with a decrease in cracked products was reported. The increased Sn content
Recent Developments on Clean Fuels over SAPO-Type Catalysts