ACS Catalysis
Research Article
catalyst under the reaction conditions. The parent furfural
spectra exhibit peaks at 767, 948, and 1016 cm− (ascribed to
performance. These results indicate that Lewis acidity is
responsible for ring rearrangement and hydrolysis steps, while
Brønsted acidity tends to induce carbon loss.
1
−
1
the signal of the furan ring group) and 1683 cm (ascribed to
2
5
the signal of the CO group). Over the surface of Ni P and
2
−
1
Co P, the CO group peak red-shifted to 1717 cm , but the
CONCLUSIONS
2
■
2
6
positions of the furan ring peaks remain unchanged. Thus,
A series of highly tunable metal phosphate nanoparticles was
used as a bifunctional catalyst for the hydrogenative ring
opening and ring rearrangement of furfural. The hydrogen
activation ability, furfural adsorption configuration, and acidity
of metal phosphate greatly affect their catalytic ability and
selectivity. Compared with the result of Pd/C with THFA as
the main product, the CoP shows a PTL yield above 80% due
to the flat adsorption of furfural, suitable hydrogenation ability,
Ni P and Co P only absorb the CO group of furfural by a
2
2
vertical configuration. In contrast, over CoP and Pd/C, both
CO and furan ring group peaks have been red-shifted by
approximately 10 and 30 cm− (Figure 5A), which suggests
that both furan and CO groups can be adsorbed by a flat
configuration. This adsorption configuration ensures highly
selective CO hydrogenation of Ni P and Co P, whereas
1
2
2
both CO and furan ring hydrogenation of CoP and Pd/C.
Compared with Pd/C, the relatively weak hydrogenation
ability and abundant acid sites of CoP make a semi-
hydrogenation of the furan ring and subsequent ring opening,
instead of the excessive hydrogenation of FA to THFA. To
investigate previously reported solvent effects on selective
and acid-catalyzed properties. Ni P shows a CPL yield of
2
62.8% due to the vertical adsorption. Furthermore, these
nanoparticles maintain their catalytic activity after loading on
the inert support and are easy to separate and be reused at least
four times. This work provides an efficient synthetic path for
PTL and CPL and shows an interesting strategy of the
regulation reaction route by the adsorption configuration
reactant.
hydrogenation of furfural, where H O-mediated protonation
2
favors the selective hydrogenation of asymmetric CO,
methanol was used as the solvent for the hydrogenation
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7
reaction. After 6 h, FA and THFA were the main products
ASSOCIATED CONTENT
Supporting Information
■
2
sı
*
hydrogenation is determined by the adsorption configuration
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of the reactant rather than by the H O-mediated effect. To
2
verify the interaction of the furan ring with the catalyst, an
Some catalyst physicochemical properties and catalytic
adsorption test of FA from H O over various metal phosphides
2
reaction results, namely, N2 adsorption−desorption
was explored (Figures 5B and S17). The adsorption capacity
and rate of CoP is larger than that of Ni P and Co P.
isotherms, NH -TPD, pyridine-adsorbed FTIR spectra,
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2
2
thermogravimetric analysis, GC−MS patterns, XRD,
TEM micrographs, XPS spectra, the catalytic effect of
the Brønsted acid amount, temperature, and pH,
catalytic kinetics, contact angle test, and UV−vis
absorption spectrum (PDF)
Meanwhile, during the in situ reaction process, the
concentration of FA in the reaction liquid mixture cannot be
largely detected over CoP, whereas a maximum FA
concentration of 10.0−20.0% appeared over Ni P and Co P.
2
2
These results indicate the strong interaction of the furan ring
over CoP and Ni P, which is conducive to the hydrogenation
2
of the furan ring and subsequent ring opening for PTL. The
PTL catalytic performance results from the precise synergistic
effect of hydrogenation and acid catalysis over metal
phosphates.
Corresponding Authors
■
Qiang Deng − Key Laboratory of Poyang Lake Environment
and Resource Utilization (Nanchang University) of Ministry
of Education, School of Resource, Environmental and
The blank experiment shows the slow generation of HCP
+
from FA catalyzed by the water-dissociated H , so FA that is
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9
Shuguang Deng − School for Engineering of Matter, Transport
pH of the reaction mixture was adjusted to decrease the
+
concentration of H . When the pH of the reaction solution was
increased from 7.0 to 10.5 by adjusting the basic Na CO , the
2
3
8
PTL selectivity increased from 60.6 to 65.7%. In contrast, the
acidic reaction solution with a pH of 5 (adjusted by
CH COOH) caused a large decrease in PTL selectivity
Authors
3
(
(
34.1%) and an increase in cyclic compound selectivities
CPL 40.7% and CPO 18.8%), which was accompanied by the
.3% selectivity of humins by Brønsted acid catalysis (Figure
Zhikun Tong − Key Laboratory of Poyang Lake Environment
and Resource Utilization (Nanchang University) of Ministry
of Education, School of Resource, Environmental and
330031, PR China
Xiang Li − Key Laboratory of Poyang Lake Environment and
Resource Utilization (Nanchang University) of Ministry of
Education, School of Resource, Environmental and Chemical
China
S18). To better verify the relationship between acidity and
catalytic performance, a series of in situ titrations was carried
out using pyridine and 2,6-di-tert-butylpyridine as titrants.
Pyridine can bind both Lewis- and Brønsted-acid sites, whereas
30
2
,6-di-tert-butylpyridine is selective to Brønsted-acid sites.
For Co P, pyridine deactivates acid sites and the main product
2
is changed from CPO to FA, whereas 2,6-di-tert-butylpyridine
does not significantly reduce the yield of cyclic compounds,
and the amount of carbon loss is greatly reduced (Figure S19).
For CoP, 2,6-di-tert-butylpyridine does not change the catalytic
Jingyu Dong − Key Laboratory of Poyang Lake Environment
and Resource Utilization (Nanchang University) of Ministry
of Education, School of Resource, Environmental and
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412
ACS Catal. 2021, 11, 6406−6415
Tong, Zhikun
