635
Step 1: The activation of the FUR molecule carried out by the adsorption on the
Ni 3 Sn 2 active site through the terminal oxygen atom of carboxide attaching to the
top site of the metallic Ni.
Step 2: Dissociation of molecular H 2 produces active hydrogen atoms on the
adjacent Ni species.
Step 3: Firstly, active H atom of a bridge site attacks the carbon atom of carboxide with the formation of an alkoxide intermediate.
Step 4: The alkoxide intermediate undergoes sequential hydrogenation at the
oxygen atom to produce FA.
Step 5: FA desorbs from the surface of the nanocomposite.
Furthermore, Shi et al. investigated the performance of SiO 2 -supported Ni-based
bimetallic catalyst for the hydrogenation of FUR to FA using isopropanol as a solvent [61]. Bimetallic Ni-Fe nanoparticles in the bimetallic catalyst exhibited better
performance with 97–100% FUR conversion at 423 K under 20 MPa H 2 pressure
after 120 min. Furthermore, depending on the process conditions, the type of supported metal catalyst, and the solvent, FUR hydrogenation produced numerous
products [57]. In Fig. 3, the inset shows a parity plot between the measured and
calculated rates of FUR hydrogenation over the range of 80–120 °C.
The selective hydrogenation of FUR could also produce potential fuel components such as 2-methylfuran (2-MF) via direct hydrogenation of aldehyde group or
by second step hydrogenation [70–74]. 2-MF is an excellent liquid fuel additive
with relatively high energy density, boiling points, and octane numbers and can be
partially blended with engine gasoline. Yan et al. reported 51% yield of 2-MF with
an inexpensive Cu-Fe nanocomposite with Cu
2+
/Fe
3+
ratio of 2 under the conditions
of 493 K and 90 bar initial H 2 pressure after 14 h [73]. It was observed that the
acidic center present on the Cu-Fe catalyst is responsible for the dehydration of
FUR to MF. In another study, Seemala et al. explored the effect of bimetallic Cu-Ni
nanoparticle composition with varying Ni loading (0, 0.5, 1.5, 3, 5, and 10 wt %) at
a constant Cu loading of 5 wt% and support (Al 2 O 3 and TiO 2 ) on the HDO of FUR
[74]. It has been observed that TiO 2 -supported Cu-Ni bimetallic nanoparticles promote the formation of Cu-rich near-surface alloys containing predominantly dispersed Ni species. Alternatively, in Cu-Ni bimetallic particles supported on Al 2 O 3
support, Cu and Ni are evenly distributed throughout the particles, and there exists
segregation of Ni and Cu domains at the particle surfaces. As a result of the supportinduced changes in the compositional structure of the bimetallic Cu-Ni nanoparticle
surfaces, TiO 2 as support primarily resulted in the formation of 2-MF, while FA and
THFOL were the main products with Al 2 O 3 as support. A maximum 2-MF yield of
87% with 99% FUR conversion was reported over Cu(5%)-Ni(5%)/TiO 2 at 473 K
after 2 h under 35 bar initial H 2 pressures in the presence of 1,4-dioxane as a solvent.
In a recent study, Zhang et al. investigated the CTH of FUR to 2-MF and 2-MTHF
over Al 2 O 3 -supported Cu and Ni bimetallic catalyst in the presence of isopropanol
as a H-donor solvent [70]. Under optimal conditions, a 64.8% yield of 2-MF and a
17.7% yield of 2-MTHF (82.5% yield in total) were achieved at a temperature of
503 K for 4 h over CuNi 2 Al. In addition, 2-MTHF could also be selectively formed
with 51.2% yield at 523 K after 9 h with CuNi 2 Al. Niu et al. reported inexpensive
Efficient Nanocomposite Catalysts for Sustainable Production of Biofuels and…
Step 1: The activation of the FUR molecule carried out by the adsorption on the
Ni 3 Sn 2 active site through the terminal oxygen atom of carboxide attaching to the
top site of the metallic Ni.
Step 2: Dissociation of molecular H 2 produces active hydrogen atoms on the
adjacent Ni species.
Step 3: Firstly, active H atom of a bridge site attacks the carbon atom of carboxide with the formation of an alkoxide intermediate.
Step 4: The alkoxide intermediate undergoes sequential hydrogenation at the
oxygen atom to produce FA.
Step 5: FA desorbs from the surface of the nanocomposite.
Furthermore, Shi et al. investigated the performance of SiO 2 -supported Ni-based
bimetallic catalyst for the hydrogenation of FUR to FA using isopropanol as a solvent [61]. Bimetallic Ni-Fe nanoparticles in the bimetallic catalyst exhibited better
performance with 97–100% FUR conversion at 423 K under 20 MPa H 2 pressure
after 120 min. Furthermore, depending on the process conditions, the type of supported metal catalyst, and the solvent, FUR hydrogenation produced numerous
products [57]. In Fig. 3, the inset shows a parity plot between the measured and
calculated rates of FUR hydrogenation over the range of 80–120 °C.
The selective hydrogenation of FUR could also produce potential fuel components such as 2-methylfuran (2-MF) via direct hydrogenation of aldehyde group or
by second step hydrogenation [70–74]. 2-MF is an excellent liquid fuel additive
with relatively high energy density, boiling points, and octane numbers and can be
partially blended with engine gasoline. Yan et al. reported 51% yield of 2-MF with
an inexpensive Cu-Fe nanocomposite with Cu
2+
/Fe
3+
ratio of 2 under the conditions
of 493 K and 90 bar initial H 2 pressure after 14 h [73]. It was observed that the
acidic center present on the Cu-Fe catalyst is responsible for the dehydration of
FUR to MF. In another study, Seemala et al. explored the effect of bimetallic Cu-Ni
nanoparticle composition with varying Ni loading (0, 0.5, 1.5, 3, 5, and 10 wt %) at
a constant Cu loading of 5 wt% and support (Al 2 O 3 and TiO 2 ) on the HDO of FUR
[74]. It has been observed that TiO 2 -supported Cu-Ni bimetallic nanoparticles promote the formation of Cu-rich near-surface alloys containing predominantly dispersed Ni species. Alternatively, in Cu-Ni bimetallic particles supported on Al 2 O 3
support, Cu and Ni are evenly distributed throughout the particles, and there exists
segregation of Ni and Cu domains at the particle surfaces. As a result of the supportinduced changes in the compositional structure of the bimetallic Cu-Ni nanoparticle
surfaces, TiO 2 as support primarily resulted in the formation of 2-MF, while FA and
THFOL were the main products with Al 2 O 3 as support. A maximum 2-MF yield of
87% with 99% FUR conversion was reported over Cu(5%)-Ni(5%)/TiO 2 at 473 K
after 2 h under 35 bar initial H 2 pressures in the presence of 1,4-dioxane as a solvent.
In a recent study, Zhang et al. investigated the CTH of FUR to 2-MF and 2-MTHF
over Al 2 O 3 -supported Cu and Ni bimetallic catalyst in the presence of isopropanol
as a H-donor solvent [70]. Under optimal conditions, a 64.8% yield of 2-MF and a
17.7% yield of 2-MTHF (82.5% yield in total) were achieved at a temperature of
503 K for 4 h over CuNi 2 Al. In addition, 2-MTHF could also be selectively formed
with 51.2% yield at 523 K after 9 h with CuNi 2 Al. Niu et al. reported inexpensive
Efficient Nanocomposite Catalysts for Sustainable Production of Biofuels and…