Effect of preparation temperature on the structures and hydrodeoxygenation performance of Ni2P/C catalysts prepared by decomposition of hypophosphites

Article abstract of DOI:10.1039/c8nj04628j

A novel method for preparing Ni₂P/C-x (x = preparation temperature, °C) catalysts in a flowing N₂ atmosphere by decomposition of hypophosphites was proposed, and the effect of preparation temperature on the hydrodeoxygenation performance of the catalysts was further investigated. X-ray diffraction (XRD), N₂-adsorption specific surface area measurements, CO uptake, and X-ray photoelectron spectroscopy (XPS) were applied. The performances of the Ni₂P/C-x catalysts prepared at different preparation temperatures were tested in the benzofuran hydrodeoxygenation (BF HDO) reaction. The diffraction peaks related to Ni₂P can be seen when x ≧ 400 °C. With increasing x, the Ni₂P crystallite size and CO uptake amount of the Ni₂P/C-x catalysts increased, and the amount of phosphorous decreased. The BF conversion and yield of total O-free products over the Ni₂P/C-x catalysts increased with increasing preparation temperature. The Ni₂P/C-550 catalyst showed a BF HDO conversion of 91.6% and a yield of total O-free products of 70.2% under the reaction conditions of 300 °C, 3.0 MPa, a H₂/oil ratio of 500 (V/V), and a weight hourly space velocity (WHSV) of 4.0 h^?1.

Full text of DOI:10.1039/c8nj04628j

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Effect of preparation temperature on the
structures and hydrodeoxygenation performance
of Ni2P/C catalysts prepared by decomposition
of hypophosphites†
Cite this: New J. Chem., 2018,
42, 19917
Xueya Dai, Hua Song, * Zijin Yan, Feng Li, Yanguang Chen, Xueqin Wang,
Dandan Yuan, Jiaojing Zhang and Yuanyuan Wang
A novel method for preparing Ni2P/C-x (x = preparation temperature, 1C) catalysts in a flowing N2
atmosphere by decomposition of hypophosphites was proposed, and the effect of preparation
temperature on the hydrodeoxygenation performance of the catalysts was further investigated. X-ray
diffraction (XRD), N2-adsorption specific surface area measurements, CO uptake, and X-ray photo-
electron spectroscopy (XPS) were applied. The performances of the Ni2P/C-x catalysts prepared at
different preparation temperatures were tested in the benzofuran hydrodeoxygenation (BF HDO)
reaction. The diffraction peaks related to Ni2P can be seen when x ^ 400 1C. With increasing x, the Ni2P
crystallite size and CO uptake amount of the Ni2P/C-x catalysts increased, and the amount of
phosphorous decreased. The BF conversion and yield of total O-free products over the Ni2P/C-x
catalysts increased with increasing preparation temperature. The Ni2P/C-550 catalyst showed a BF HDO
conversion of 91.6% and a yield of total O-free products of 70.2% under the reaction conditions of
Received 11th September 2018,
Accepted 22nd October 2018
DOI: 10.1039/c8nj04628j
300 1C, 3.0 MPa, a H2/oil ratio of 500 (V/V), and a weight hourly space velocity (WHSV) of 4.0 hꢀ1
.
rsc.li/njc
cheap cost and high hydrotreating activity.4 Among them,
Ni2P with unique physical and chemical properties is the most
1. Introduction
Biomass, the most abundant and inexpensive renewable promising catalyst.5
resource, has been attracting much attention. Bio-oil produced
Several preparation methods of Ni2P catalysts have been
from biomass is a potential liquid fuel to replace fossil fuels in reported in the literature. Temperature programmed reduction
the current conversion system and energy production. However, (TPR) of a nickel metal salt together with a phosphate under
bio-oil contains a high fraction of oxygenated compounds, which flowing hydrogen is a traditional method for the preparation of
degrade the physical and chemical stability of bio-oil. The oxygen Ni2P, which has the disadvantage of requiring high treatment
in bio-oil can be removed by catalytic hydrodeoxygenation (HDO). temperatures (4650 1C).6 Besides the TPR method, some new
Therefore, the development of highly active HDO catalysts has methods have been proposed for the preparation of Ni2P, such
received much attention.1–3
as solution-phase reactions,7 reduction of nickel dihydrogen-
A series of catalysts has been studied for HDO, such as phosphite,8 thermal decomposition of nickel thiophosphate
conventional sulfide catalysts, noble metal catalysts, and transi- (NiPS3),9 thermal decomposition of trioctylphosphine (TOP)
tion metal phosphides. Sulfide catalysts have a drawback in together with metal salt precursors,10,11 plasma methods,12
that they require the addition of environmentally unfriendly and thermal decomposition of hypophosphites or dihydrogen-
sulfur to maintain their catalytic activity. Noble metal catalysts phosphite in an inert atmosphere. Of all these preparation
are too expensive for industrial applications. The transition methods, the thermal decomposition of hypophosphites or
metal phosphides, such as Ni2P, WP, Co2P, MoP and NiMoP, have dihydrogenphosphite in an inert atmosphere is particularly
attracted much attention due to their widespread availability, noteworthy with the advantage of a lower preparation tempera-
ture and no need for H2.13 Song et al.14 prepared bulk and
supported Ni2P/SiO2 catalysts using NaH2PO3 and NiCl2ꢁ6H2O
as precursors with the initial molar ratio of H2PO3ꢀ/Ni2+ = 5 in
Provincial Key Laboratory of Oil & Gas Chemical Technology, College of Chemistry
& Chemical Engineering, Northeast Petroleum University, Daqing 163318,
flowing N2 at 250 1C, in which dihydrogenphosphite released
Heilongjing, China. E-mail: songhua2004@sina.com; Fax: +86 0459 6503167;
PH3 when it decomposed. PH3 can reduce NiCl2ꢁ6H2O to
Tel: +86 0459 6503167
† Electronic supplementary information (ESI) available. See DOI: 10.1039/c8nj04628j form Ni2P. They found that too low or too high a treatment
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temperature and a low H2PO3ꢀ/Ni2+ molar ratio would lead to was investigated. Furthermore, a BF HDO reaction route was
the formation of Ni12P5 besides the main phase of Ni2P. The proposed to interpret the catalytic behavior of the catalyst.
conversion of dibenzothiophene (DBT) hydrodesulfurization
(HDS) over Ni2P/SiO2 was found to be about 93% and 100%
at 340 1C and 360 1C, respectively. Guan et al.15 prepared bulk
Ni2P, Ni2P/Al2O3 and Ni2P/MCM-41 by heating NiO (calcined
from Ni(NO3)2) together with NaH2PO2 in a static Ar atmo-
In order to determine the proper initial P/Ni molar ratio, bulk
sphere. The prepared Ni2P/Al2O3 and Ni2P/MCM-41 catalysts
2. Experimental methods
2.1. Preparation of bulk and supported nickel phosphide
nickel phosphide catalysts with different initial P/Ni molar
ratios (P/Ni = 2, 3, 4, and 5) were synthesized by dissolving
NH4H2PO2 and Ni(CH3COO)2ꢁ4H2O in deionized water. In a
showed a DBT HDS activity of 84% and 100% at 330 1C,
respectively. Similarly, Bowker et al.16 prepared a Ru2P/SiO2
catalyst, and they used hypophosphite as a reductant to reduce
Ru3+. The prepared Ru2P/SiO2 catalyst had a furan HDO activity
of 12 390 nmol furan gꢀ1 sꢀ1 at 400 1C. From the above, the
thermal decomposition of hypophosphites or dihydrogenphos-
phite is a promising method for the preparation of Ni2P due to
its lower preparation temperature and no need for H2. However,
most of the prepared Ni2P catalysts were applied in the HDS
reaction and seldom used in the HDO reaction.
typical experiment (P/Ni = 2), 8.04 mmol of Ni(CH3COO)2ꢁ4H2O
and 16.08 mmol of NH4H2PO2 were respectively dissolved in
20 mL of deionized water at room temperature to form uniform
solutions. The solutions were evaporated at 60 1C for 12 h until
they were dehydrated. The obtained solids were then ground
using a mortar and pestle to form ready-to-use precursors. The
precursors (0.3 g) were placed in a fixed-bed reactor, heated to
400 1C, at a rate of 3 1C minꢀ1 in a flow of N2 (30 mL minꢀ1),
held for 2 h, then naturally cooled to 100 1C and held for
another 1 h in flowing air (30 mL minꢀ1), instead of being
passivated with an O2/N2 mixture. In this way, the reactivation
step of the catalyst under high temperature in a H2 flow prior to
reaction, like the conventional method, can be omitted.24,25
To make the Ni2P/C-x catalysts, a calculated C (activated
carbon, Xuan Cheng Jing Rui New Material Co., Ltd, 16/20
mesh, washed with deionized water and dried at 100 1C for
10 h) support was added to the solution of NH4H2PO2 and
Ni(CH3COO)2ꢁ4H2O (initial P/Ni molar ratio = 4, Ni = 10 wt%).
In a typical experiment, 3.38 mmol of Ni(CH3COO)2ꢁ4H2O and
13.61 mmol of NH4H2PO2 were dissolved in 20 mL of deionized
water at room temperature to form a uniform solution. 2.0 g of
the C support was wet-impregnated with the above solution for
12 h. The subsequent steps and conditions are the same as
those for synthesizing bulk nickel phosphide catalysts. The
precursor (0.3 g) was placed in a fixed-bed reactor and heated to
350 1C, 400 1C, 450 1C, 500 1C and 550 1C, respectively. The
catalysts obtained were named as Ni2P/C-x, where the x was
defined as the thermal treatment temperature (1C).
The difference in terms of Ni sources can affect the structure
and activity of the Ni2P catalyst. Nickel acetate (Ni(CH3COO)2ꢁ4H2O)
is a potential Ni source for high surface area and uniform particles
of catalysts.17 Dharmaraj et al.17 prepared NiO particles with
uniform size and good dispersion using nickel acetate as a Ni
source. They found that the nickel acetate coordinated with
poly(vinyl acetate) could prevent the aggregation of NiO during
heat treatment. When Ni(CH3COO)2ꢁ4H2O is heated in an inert
atmosphere, CO produced from the thermal decomposition
of the acetate group reduces the Ni2+ state to Ni.18,19 Inspired
by this, a novel method to prepare a Ni2P catalyst using
Ni(CH3COO)2ꢁ4H2O as the Ni source in an inert atmosphere
by the thermal decomposition of hypophosphite is proposed in
this study. Besides the influence of Ni sources, the preparation
temperature is another important condition to modulate the
structure and activity of the catalyst. Wang et al.20 investigated the
effect of calcination and reduction temperatures on unsupported
Ni2P catalysts. The results indicated that the highest Ni2P surface
area could be obtained from a precursor calcined at 500 1C and
reduced in H2 at 650 1C, and the smallest Ni2P crystallite size
was obtained at 500 1C. Chen et al.21 revealed the influence of
the reduction temperature (400–550 1C) for NiMoO3-x/SAPO-11
catalysts on the HDO performance of methyl laurate, involving
2.2. Characterization
the aspects of deoxygenation activity, isomerization selectivity X-ray diffraction (XRD) analysis was carried out on a D/max-
and deoxygenation pathway. The NiMo3-x/SAPO-11 catalyst 2200PC-X-ray diffractometer using Cu Ka radiation, with the
reduced at 400 1C exhibited a low deoxygenation activity with scan range from 10 to 801 at a rate of 101 minꢀ1. All the samples
the highest isomerization selectivity. However, the effect of were air-modified catalysts. The typical physico-chemical pro-
preparation temperature on the supported Ni2P catalysts using perty of the catalysts was analyzed by the BET method using a
Ni(CH3COO)2ꢁ4H2O as a Ni source in an inert atmosphere by micromeritics adsorption Tristar II 3020 instrument. All the
the thermal decomposition of hypophosphite has not been samples were treated at 200 1C under vacuum conditions with
thoroughly studied yet.
the pressure of 6 mmHg. The adsorption isotherms for nitrogen
Activated carbon (C) has large average pore diameters, and were measured at ꢀ196 1C. CO uptake measurement was
large surface areas and pore volumes, and it is an economical performed in a Micromeritics ASAP 2010 apparatus. Typically,
support for various catalysts.22,23 Using C as a support, a series 0.2 g of catalyst was loaded in a quartz reactor and treated in a
of Ni2P/C catalysts were prepared from Ni(CH3COO)2ꢁ4H2O and continuous He flow (30 mL minꢀ1) for 30 min at 200 1C to remove
ammonium hypophosphite (NH4H2PO2) at different tempera- moisture, then naturally cooled down to room temperature
tures in a flowing N2 atmosphere. The effect of temperature on to achieve an adsorbate-free state by flushing for 30 min. After
the textural characterization and benzofuran (BF) HDO activity pre-treatment, pulses of CO (1 mL) were injected into the flow of
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He (30 mL minꢀ1), which were repeatedly injected until the
response from the detector showed no further CO uptake after
consecutive injections. The CO uptake was calculated by mea-
suring the decrease in peak areas due to adsorption. The X-ray
photoelectron spectroscopy (XPS) spectrum was acquired using
an ESCALAB MKII spectrometer under vacuum. XPS measure-
ment was performed with Mg radiation (E = 1253.6 eV) and a
hemi-spherical analyzer operating at a fixed pass energy of
40 eV. The recorded photoelectron binding energy was refer-
enced against the C 1s contamination line at 284.8 eV. All the
samples were air modified catalysts.
2.3. Catalytic activity test
The reaction was performed in a flowing high-pressure fixed-
bed stainless steel catalytic reactor (0.8 cm in diameter and
40 cm in length), using a feed consisting of a decalin solution of
BF (2 wt%). The conditions for the HDO reaction were 300 1C,
3.0 MPa, weight hourly space velocity (WHSV) = 4.0 hꢀ1, and a
hydrogen/liquid ratio of 500 (V/V). The feed and reaction
product were analyzed by flame ionization detector (FID) gas
chromatography (Shimadzu GC-14C) equipped with a capillary
column (PH-1, 60 m ꢂ 0.25 mm). The temperature program was
heating at a rate of 20 1C minꢀ1 from 70 1C to 250 1C, then
holding at 250 1C for 1 min.
Fig. 1 XRD patterns of Ni2P/C-x catalysts.
Table 1 Properties of C support and Ni2P/C-x catalysts
b
SBET
Vp
Da dXRD CO uptake Yields of O-free
Sample
(m2
g
ꢀ1) (cm3
g
ꢀ1) (nm) (nm) (mmol gꢀ1) product (%)
C support 907
Ni2P/C-400 218
Ni2P/C-450 221
Ni2P/C-500 263
Ni2P/C-550 284
0.31
0.14
0.15
0.17
0.17
1.37
—
—
—
2.57 18.5 32
2.71 18.9 33
2.59 20.0 35
2.39 25.6 36
62.9
66.0
67.0
70.2
The conversion of BF (XBF), the selectivities and yields of
O-free products, and the selectivity (Si) were defined as follows,
respectively:
a
b
D: pore diameter, D = 4VBJH/SBET
.
dXRD: calculated from the Scherrer
equation based on Ni2P {1 1 1}.
ꢀ
ꢁ
nBF
XBF
¼
1 ꢀ
ꢂ 100%
(1)
nBF;0
(PDF: 03-0953), ascribed to the Ni2P phase, can be clearly seen.
No other phase related to Ni or P could be seen, indicating that
the active phase was mainly Ni2P.
O-free product
ꢂ 100%
all product
SelectiviesO-free
¼
(2)
The average size of the Ni2P crystallites estimated by the
Scherrer equation is shown in column 5 of Table 1. The average
size of the Ni2P crystallites increased from 18.5 nm (Ni2P/C-400)
to 20.0 nm (Ni2P/C-500) with increasing preparation temperature
from 400 1C to 500 1C. But, when increasing the temperature from
500 1C to 550 1C (25.6 nm), the average size of the Ni2P crystallites
showed an increase of 5.6 nm, which is large. Similar results were
reported by Wang et al.,20 in which the crystallite size of Ni2P
increased gradually from 9 to 20 nm with the reduction tempera-
ture increasing from 500 to 650 1C.
YieldsO-free ¼ Conversion ꢂ SelectiviesO-free ꢂ 100%
(3)
(4)
ni
P
Si ¼
ꢂ 100%
ni
where nBF,0 and nBF are the moles of BF in the feed and product,
respectively, and ni is the moles of product i.
3. Results and discussion
3.1. XRD patterns of the Ni2P/C-x catalysts
3.2. N2 adsorption of Ni2P/C-x catalysts
Fig. S1 (ESI†) shows the XRD patterns of the bulk samples with Fig. 2 shows the N2 adsorption–desorption isotherms for the
different initial P/Ni molar ratios. All samples showed Ni2P C support and Ni2P/C-x catalysts. As can be seen from Fig. 2, the
phase peaks at 2y = 40.61, 44.51, 47.11 and 54.11 (PDF: 03-0953). samples displayed a type IV isotherm and a standard H4 type
However, the pure Ni2P phase could only be obtained for the hysteresis loop according to the IUPAC classification, showing
catalysts with an initial P/Ni ratio higher than 4.
XRD patterns were used to identify the crystalline phases. properties of the support and catalysts. The surface area and
Fig. 1 shows the XRD patterns of the C support and Ni2P/C-x pore volume of the C support were 907 m2 gꢀ1 and 0.31 cm3 gꢀ1
the presence of some mesopores. Table 1 shows the textural
,
catalysts. For the C support, the broad diffraction peaks located respectively. The surface area and pore volume of the
at 2y = 23.91 and 42.71 were due to the amorphous nature of the Ni2P/C-x catalysts decreased significantly as compared to those
micropore structure.26 For Ni-P/C-350, the diffraction peaks of the C support, which was due to the blockage of pores by
related to Ni2P did not appear. With increasing preparation loading the nickel phosphide phase. The Ni2P/C-400 catalyst
temperature, the peaks at 2y = 40.61, 44.51, 47.11 and 54.11 showed a surface area of 218 m2
g
ꢀ1. With the increase of
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catalysts. As can be seen from Table 1, the CO uptake of Ni2P/
C-400 was 32 mmol gꢀ1, which is low compared to those of the
other catalysts prepared at higher temperatures. The low CO
uptake of Ni2P/C-400 was possibly due to the enrichment
of phosphate species on the surface (see XPS analysis) at a
lower preparation temperature. With increasing preparation
temperature, the CO uptake increased, showing more active
Ni sites could be exposed on the surface of the catalysts. This is
because a higher preparation temperature is beneficial to
suppress the enrichment of phosphate species on the surface
(see XPS analysis).
3.4. XPS spectra of the Ni2P/C-x catalysts
The XPS spectra were analysed to gain further insight into
the valence states of the active components and the surface
composition of the catalysts. Fig. 3 shows the XPS spectra for
the Ni 2p and P 2p lines of the Ni2P/C-400 and Ni2P/C-550
catalysts. As shown in Fig. 3(a), the peaks centered at 853.5 eV
can be assigned to Nid+ (0 o d o 2) in Ni2P. The peaks centered
at 856.3–856.4 eV correspond to the possible interaction of Ni2+
ions with phosphate ions, as a consequence of a superficial
passivation, along with the broad shake-up peak at approxi-
mately 6.0 eV higher than that of the Ni2+ species.29 In Fig. 3(b),
the peaks centered at 130.2–130.3 eV can be assigned to Pdꢀ
(0 o d o 1) in the Ni2P phase and the peak at 134.5–134.6 eV
can be assigned to P5+ due to the superficial oxidation.30
The superficial atomic ratios of P/Ni obtained from XPS are
listed in column 7 of Table 2. The initial P/Ni molar ratio of
Ni2P/C-x was 4. However, the data from XPS analysis showed
that Ni2P/C-400 and Ni2P/C-550 exhibited lower P/Ni ratios than
4, which may be because of the release of PH3 during the
Fig. 2 Nitrogen adsorption/desorption isotherms of the C support and
Ni2P/C-x catalysts.
temperature, the surface area increased. The surface area of
the Ni2P/C-500 catalyst increased to 263 m2
g
ꢀ1. But, when
increasing the temperature from 500 1C to 550 1C, the increase
of surface area was little.
The results indicated that a higher preparation temperature
is beneficial to obtain a large surface area, which coincides with
those of the previously published studies.13 This can be attri-
buted to a decrease in the enrichment of phosphorus on the
surface of the catalysts with increasing preparation temperature.
This will be further discussed in Section 3.4 XPS analysis.
3.3. CO uptake of Ni2P/C-x catalysts
The CO uptakes of the catalysts are listed in column 6 of preparation. But, the P/Ni ratios of Ni2P/C-x were still higher
Table 1. The CO uptake data were measured five times and than the theoretical P/Ni ratio of 0.5 of the Ni2P phase, which
the listed data are the average values. The average error was less may be due to the enrichment of phosphorous on the surface.
than 5.5%. According to the literature,27,28 the CO molecules The superficial P/Ni ratio of Ni2P/C-400 was 3.07, and that of
are mainly adsorbed at Ni sites; therefore, the amount of Ni2P/C-550 decreased to 2.15. This indicated that a higher pre-
CO uptake can reflect the amount of exposed Ni sites on the paration temperature was beneficial to suppress the enrichment
Fig. 3 XPS patterns in the Ni(2p) and P(2p) regions of the Ni2P/C-x catalysts. (a) Ni 2p core level spectra and (b) P 2p core level spectra.
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Table 2 Proportion of each species from the Ni(2p) and P(2p) spectra
obtained by XPS analysis
Binding energy (eV)
Ni 2p3/2
Nid+ Ni2+ Satellite Pd–
P 2p
Superficial atomic
ratio P/Ni
Sample
P5+
Ni2P/C-400 853.5 856.3 861.1
Ni2P/C-550 853.5 856.4 861.3
130.3 134.6 3.07
130.2 134.5 2.15
Fig. 5 Product selectivities of BF HDO over Ni2P/C-x catalysts.
phase (CO analysis) was exposed on the surface of catalysts
prepared at higher temperature. But, the increase of temperature
has less impact on the BF conversion when the temperature was
higher than 500 1C.
Fig. 5 depicts the HDO product distribution of the Ni2P/C-x
catalysts after 8 h. The main products detected were ethylcyclo-
hexane (ECH), methylcyclohexane (MCH), 2-ethylphenol (2-EtPh),
ethylbenzene (EB) and 2,3-dihydrobenzofuran (2,3-DHBF). Trace
products observed were phenol (Ph), methylbenzene (MB) and
benzene (B). The EB, ECH, MCH, MB and B were O-free products.
On the basis of the product distribution and literature
description,25 a possible reaction route for BF HDO over Ni2P/
C-x catalysts is shown in Scheme 1. The first step involved the
hydrogenation of the furan ring on BF, which led to the
formation of 2,3-DHBF, then 2,3-DHBF was further converted
into 2-EtPh by a C–O bond cleavage of the heterocyclic
ring through hydrogenolysis. EB is obtained from 2-EtPh by
dehydration, then converted into ECH by hydrogenation of
Fig. 4 Conversion of BF HDO over Ni2P/C-x catalysts.
of phosphorous, possibly related with the release of a larger
amount of PH3 at higher temperature.
3.5. Catalytic results and reaction pathways
Fig. 4 depicts the reaction of BF HDO over the Ni2P/C-x catalysts the benzene ring, followed by demethylation of ECH to MCH.
as a function of reaction time. As shown in Fig. 4, the BF For the trace products, EB is transformed into B and MB
conversion gradually increased and then remained stable with via hydrogenation of the ethyl group. B can also be formed
time. The improved catalytic activities within the initial time by dehydration of Ph, which is formed from 2-EtPh by
indicated that an intermediate phase, which was more active demethylation.
than Ni2P,31,32 was formed. Koranyi et al.29 reported that a super-
All Ni2P/C-x catalysts have a similar selectivity order, and the
´
ficial phosphosulfide with a stoichiometry represented by NiPxSy order of O-free product selectivity was ECH 4 EB 4 MCH 4
is the real active phase of the HDS reaction. Similar to the HDS MB 4 B, while the order of O-containing product selectivity was
reaction, the HDO conversion increasing with time-on-stream 2,3-DHBF 4 2-EtPh 4 Ph. It can be seen that the selectivity for
may be caused by the formation of a more active NiPxOy phase.33 ECH was much higher than other products over the Ni2P/C-x
The surface of the Ni2P/C catalysts was modified in air, however, catalysts. The selectivity for ECH over Ni2P/C-400 was 65.8%,
the real active NiPxOy phase for HDO could not form completely and that over Ni2P/C-550 showed an increase of 2.8% and
at the initial stage. The gradually increasing conversion of reached 68.6%. The total selectivity for O-free products over
BF with time-on-stream verifies the formation of more and Ni2P/C-400 was 73.8%, which over Ni2P/C-550 was 76.6%. The
more active NiPxOy phase. A similar result was also observed in slightly improved selectivities for O-free products with increasing
our previous experiment33 wherein the HDO activities over preparation temperature showed that the effect of preparation
Ni2P/SBA-15 catalysts gradually enhanced and remained stable temperature on the reaction route was not significant. At the same
with time-on-stream.
time, the selectivities for the main O-containing products of
The BF conversion over the Ni2P/C catalysts increased from 2,3-DHBF and 2-EtPh over Ni2P/C-x presented a slight decrease
85.2% (Ni2P/C-400) to 90.8% (Ni2P/C-500) when the preparation as the preparation temperature increased.
temperature increased from 400 1C to 500 1C. However, when
The yields of O-free compounds over Ni2P/C-x catalysts after
increasing the temperature from 500 1C to 550 1C, the BF 8 h are shown in column 7 of Table 1. The yield of O-free
conversion reached 91.6%, an increase of 0.8%. This indicates compounds over Ni2P/C-400 was 62.9%, which over Ni2P/C-550
that a higher catalyst preparation temperature was beneficial was 70.2%, showing that the higher preparation temperature is
for BF conversion, which was possibly because more active Ni2P beneficial to obtain higher HDO activity.
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Scheme 1 Reaction pathways for BF HDO over the Ni2P/C-x catalysts.
2 N. H. Zainan, S. C. Srivatsa, F. Li and S. Bhattacharya, Fuel,
2018, 223, 12.
4. Conclusions
In summary, a novel method for preparing highly active Ni2P/C-x
catalysts with Ni(CH3COO)2ꢁ4H2O as the Ni source in a flowing N2
atmosphere was proposed; and the effect of preparation tempera-
ture on the structures and hydrodeoxygenation performance of
the Ni2P/C-x catalysts was investigated. The XRD analysis
showed that for Ni-P/C-350, the diffraction peaks related to
Ni2P were not apparent. With increasing preparation tempera-
ture, the Ni2P crystallite size and CO uptake amount of the
Ni2P/C-x catalysts increased, and enrichment of phosphorous
decreased. The BF conversion and yields of O-free products over
Ni2P/C-x catalysts increased first and then increased more
slowly with increasing preparation temperature, and the effect
of preparation temperature on reaction route was not signifi-
cant. The Ni2P/C-500 catalyst with a preparation temperature
of 500 1C showed a BF HDO conversion of 90.8% and a yield of
O-free compounds of 75.9%.
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Conflicts of interest
There are no conflicts to declare.
13 H. Song, M. Dai, H. Song, X. Wan and X. Xu, Appl. Catal., A,
2013, 462–463(27), 247.
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15 Q. Guan and L. Wei, J. Catal., 2010, 271(2), 413.
16 R. H. Bowker, M. C. Smith, M. L. Pease, K. M. Slenkamp and
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The authors acknowledge the financial support from the
National Natural Science Foundation of China (21276048) and
Innovative scientific research projects of Innovative Practice
Base for Postgraduate Training in Northeast Petroleum
University (YJSCX2017-016NEPU).
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