The effect of metal (Nb, Ru, Pd, Pt) supported on SBA-16 on the hydrodeoxygenation reaction of phenol

Article abstract of DOI:10.1016/j.cattod.2018.06.046

Ordered silica materials of SBA-16 type were synthesized, characterized as to their physicochemical properties and used as supports of the active phases which were niobium, ruthenium, palladium or platinum ions. Physicochemical properties of the systems o

Full text of DOI:10.1016/j.cattod.2018.06.046

Accepted Manuscript
Title: The effect of metal (Nb, Ru, Pd, Pt) supported on
SBA-16 on the hydrodeoxygenation reaction of phenol
Authors: Agnieszka Feliczak-Guzik, Paulina Szczyglewska,
Izabela Nowak
PII:
S0920-5861(18)30857-5
DOI:
Reference:
https://doi.org/10.1016/j.cattod.2018.06.046
CATTOD 11535
To appear in:
Catalysis Today
Received date:
Revised date:
Accepted date:
29-3-2018
18-6-2018
30-6-2018
Please cite this article as: Feliczak-Guzik A, Szczyglewska P, Nowak I, The effect of
metal (Nb, Ru, Pd, Pt) supported on SBA-16 on the hydrodeoxygenation reaction of
phenol, Catalysis Today (2018), https://doi.org/10.1016/j.cattod.2018.06.046
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The effect of metal (Nb, Ru, Pd, Pt) supported on SBA-16 on
the hydrodeoxygenation reaction of phenol
Authors
Agnieszka Feliczak-Guzik, Paulina Szczyglewska, Izabela Nowak
Adam Mickiewicz University in Poznan, Faculty of Chemistry, 89b Umultowska, 61-614
Poznan, Poland;
Graphical abstract
Highlights
 Variation of impregnation process on physicochemical properties of the systems obtained
 Application of mesoporous materials with Nb, Ru, Pt, Pd in the catalytic reactions
 Effect of type of active phase (metal) on HDO reaction

Abstract
Ordered silica materials of SBA-16 type were synthesized, characterized as to their
physicochemical properties and used as supports of the active phases which were niobium,
ruthenium, palladium or platinum ions. Physicochemical properties of the systems obtained were
determined by XRD, N2 sorption and TEM methods. Then the materials were used as catalytic
systems in the process of phenol hydrodeoxygenation. The reaction was carried out in the range
90-130°Cunder hydrogen pressure of 2,5-6 MPa. The effects of three variables on the course of
the process were evaluated:(i) temperature, (ii) hydrogen pressure, (iii) type of active phase
(metal). The main product of the reaction with the use of catalysts SBA-16/Ru, SBA-16/Pd,
SBA-16/Pt was 2,4-dimethylhexane, while when using SBA-16/Nb, the main product was 1-
methoxy-2-hexene. In the reaction conditions applied, 100% of phenol conversion was achieved.
Direct effect of the reaction conditions, i.e., temperature and hydrogen pressure on the course of
the process was observed.
Keywords
Hydrodeoxygenation, phenol, niobium, ruthenium, palladium, platinum, SBA-16
Introduction
Increasing demand for energy and gradual depletion of fossil fuels have stimulated the
search for alternative energy sources [1, 2]. Because of the rich composition, common
occurrence and renewability, lignocellulose biomass is a valuable raw material for production of

biofuels and different chemical substances [3-6]. From among many technologies for biomass
conversion, fast pyrolysis is one of the best as it permits reaching conversions of the initial
biomaterials of up to 70 wt.% into a dense liquid known as biooil [7,8]. The liquid fuel obtained
as a result of biomass pyrolysis is a promising semiproduct that can be an alternative to fossil
fuels. However, because its low quality caused by the high content of water (up to 30 wt.%) and
the content of reactive chemical compounds such as phenols, carboxylic acids, aldehydes and
ketones, whose total content reaches even up to 50 wt.%, direct use of biooil as a biofuel is
impossible [9, 10]. Its quality must be improved so that it would be characterized by higher
calorific values, higher thermal and chemical resistance. Such an improvement requires first of
all a reduction of the content of oxygen atoms in the system as their presence is the main obstacle
in using the pyrolytic oil as a substitute of fossil fuels [11, 12].
Catalytic hydrodeoxygenation (HDO) is one of the most effective methods for biooil
improvement. This process is performed at high temperatures (150-450°C)under high hydrogen
pressure (5-25MPa) in the presence of different catalysts [13, 14]. Finally, this technology
permits a conversion of organic aromatic compounds, present in biooil and containing in their
structure oxygen atoms, into chemical compounds of higher H/C ratio at a lower O/C ratio,
which can even lead to obtaining hydrocarbons [15-17]. In laboratory scale hydrodeoxygenation
is performed using the model chemical compounds, identical to those present in biooil. The
functional groups most often occurring in biooil as methoxyl groups (-OCH3) and hydroxyl
groups (-OH), so the model compounds usually used in investigation are anisole, phenol,
guaiacol or catechol [18, 19]. High yield of the process depends to a great degree on the choice
of the catalytic system, the most effective ones employ transition metal atoms (Nb, Ru, Pd, Pt),
which easily activate hydrogen and ensure getting desired reaction products [20, 21]. The metals

are deposited on supports whose role is to ensure the best possible dispersion of the active phase
and improvement of the thermal and mechanical strength of the system [22, 23]. These criteria
are met by ordered mesoporous silica materials, which thanks to their unique morphology, i.e.
well-developed surface area and uniform pore system, are perfect supports for transition metals
[24-26]. The silicas of the types MCM (Mobil Crystalline Material), KIT (Korean Institute of
Technology) or SBA (Santa Barbara Amorphous) with transition metal ions on the surface have
been successfully applied in a number of catalytic processes involving gas hydrogen [24, 27-31].
This paper presents results obtained for hydrodeoxygenation of phenol. This process was
performed in relatively mild conditions: T=90-130°C and pressure pH2=2,5-6 MPa, applied to
minimize the use of energy. The catalysts were heterogeneous systems of metallic niobium,
ruthenium, palladium or platinum as the active component supported on mesoporous silica of
SBA-16 type. The study was aimed checking the effects of (i) temperature, (ii) pressure and (iii)
type of metal used on the degree of phenol conversion and forming reaction products.
Experimental
Catalyst preparation
The unmodified mesoporous silicas of SBA-16 type were synthesized by the standard
sol-gel method. Laboratory vessels were charged with 4.8 g of triblock copolymer of ethylene
oxide and propylene oxide, Pluronic F127 (Sigma-Aldrich), to which 460.6 g of distilled water
and 192 g 2M of hydrochloric acid (Chempur) were added. After dissolution of the structure-
directing agent (i.e. Pluronic F127), 20.2 g of TEOS (Sigma-Aldrich) were added dropwise. The
contents were stirred on a magnetic stirrer for 0.5 h at room temperature. Then the system with
the precipitate was aged in a laboratory drier for 48 h at 90°C. The precipitate obtained after
ageing was filtered off on a funnel, washed with distilled water and dried in air at room

temperature. The materials were subjected to calcination in order to remove surfactants from
silica pores (6 h, 550°C). Then the unmodified SBA-16 type silica was subjected to incipient
wetness impregnation. The vessel with a weighted portion of the support was dropwise charged
with a water solution of (NH4)3NbO(C2O4)3(H2O) (Sigma Aldrich), ethanol solution of
RuCl3*H2O (Alfa Aesar), ethanol solution of PdCl2 (Alfa Aesar) or ethanol solution of
H2PtCl6*6H2O (Alfa Aesar). The mass fraction of metals was always kept as 3 wt.%. in respect
to the support. The vessel with the impregnated support was tightly closed with polyolefin-
paraffin foil and left to rest for 24 h. Then the catalysts were dried for 1 h at 30°C, for 1 h at
40°C and 18 h at 60°C. Next, they were reduced in a tube furnace in hydrogen atmosphere in
order to obtain monometallic metal species on a mesoporous support. At first in order to remove
air from the system argon of 5.0 purity (N5.0; Linde Gas Poland) (50 cm3/min) was blown
through the system at room temperature for 0.5 h, then hydrogen was blown (50 cm3/min) and
after 0.5 h the heating was started. Depending on the metal used, the catalysts were reduced for 3
h at 400°C (niobium), 250°C (ruthenium), 350°C (palladium), 250°C (platinum).
Catalyst characterization
Physicochemical properties of all catalysts were determined on the basis of X-ray
diffraction (XRD), transmission electron microscopy (TEM) and low-temperature
adsorption/desorption of nitrogen. XRD study was performed on a Bruker AXS D8 Advance
diffractometer with a Johannson monochromator. The source of CuKαradiation generated
radiation of the wavelength α=0.154 nm in the 2Ɵ range 0.6 - 10° with the accuracy to 0.02°
(small-angle range) and in the 2Ɵ range 4 - 60° with the accuracy to 0.05° (wide-angle
range).TEM images were recorded on a JEOL JEM 1200 EX II microscope using the electron
beam of 80 kV.The low-temperature nitrogen adsorption/desorption were carried out using Nova

1200e Quantachrome at 176°C, after preliminary degassing of the sample in vacuum at 350°C
for 24 h. The specific surface area of the catalyst was determined by BET (Brauner-Emmet-
Teller) method, while the pore volume was found by the modified BJH (Barret-Joyner-Halenda)
method proposed by Kruk, Jaroniec and Sayari (KJS-BJH). Moreover, all materials were
characterized by thermogravimetry (TG), X-ray photoelectron spectroscopy (XPS), SEM/EDX
(scanning electron microscopy with EDX) and temperature programmed reduction (H2-TPR) –
see supporting information.
Experiments (HDO of phenol)
Phenol hydrodeoxygenation was carried out in a high-pressure reactor (CAT 24 HEL)
placed on a magnetic stirrer. Prior to the proper reaction, all catalysts were activated in a muffle
furnace at 400°C for 4 h. Then, the appropriate catalysts in the amounts of 0.005 g were placed
in glass reaction vessels, to which 0.05 g of phenol (Sigma-Aldrich) were added and the contents
were flooded with 1 g of dodecane (Sigma-Aldrich) used as a solvent. The glass vessels were
equipped with magnetic stirrers. The reaction mixtures were placed in a high-pressure reactor
that was tightly closed and three times washed with argon N5.0 in order to remove air from
inside the reactor. Then the reactor was twice washed with hydrogen N5.0 and finally it was
filled with hydrogen to a pressure of 2.5, 4 or 6 MPa. Then a desired temperature of 90, 110or
130°C was set and stirring was started (700 rotation per minute). The reaction was performed for
4 h and then the reactor was cooled and gas was released.
Product analysis
After removal from the high-pressure reactor, the reaction mixtures were subjected to
stirring in order to separate the liquid reaction products from the catalyst, and the products were
subjected to chromatographic analysis on a gas chromatograph with a flame-ionization detector

(VARIAN 3900 GC; a capillary column CPWAX57CB:length 25 m, diameter 0.32 mm, film
thickness 1.2 µm) and a gas chromatograph with mass detector (VARIAN 4000 GC; acapillary
column CPWAX57CB: length 25 m, diameter 0.32 mm, film thickness 1.2 µm). The reaction
products were identified by two methods, on the basis of retention times of chemical compounds
compared with retention times of available standards and using the compounds library NIST.
Results and discussion
X-ray diffraction analysis
XRD measurements in the small-angle range provide information on the degree of
ordering of the obtained materials structure (Figure 1 left). XRD diffractograms of all samples
show one intensive reflection at 2Ɵ=0.9° whose presence is the evidence of their ordered
structures. SBA-16 type silica has cage-like cubic structure of space group Im3m.
SBA-16/Pt
SBA-16/Pd
SBA-16/Pt
SBA-16/Pd
SBA-16/Ru
SBA-16/Nb
10
SBA-16/Ru
SBA-16/Nb
1
1
2
3
4
5
6
7
8
10
20
30
40
50
60
2Ɵ [°]
2Ɵ [°]

Figure 1.Small- (left) and wide-angle (right) XRD patterns of SBA-16 mesoporous silica
containing different metal atoms.
XRD diffractograms in the wide-angle range provide information confirming the
presence of relevant metals introduced by incipient wetness impregnation (Figure 1 right). Only
for two from among all samples studied: SBA-16/Pd and SBA-16/Pt, the reflections from
metallic species of relevant metals were observed. The diffractogram of sample SBA-16/Pd
shows two reflections at 2Ɵ=40.2° and 2Ɵ=46.7°. For sample SBA-16/Pt also two reflections
appear at 2Ɵ=39.8° and 2Ɵ=46.3°. The presence of these reflections confirms the successful
introduction of Pd and Pt atoms into the silica matrix, which is additionally confirmed by TEM
images. The diffractograms of SBA-16/Nb and SBA-16/Ru do not show the reflections testifying
to the presence of the respective metal ions in the silica structure, however, it is not equivalent to
the absence of these metals. The lack of reflections may be a consequence of too small sizes of
the crystallites introduced. The presence of Nb and Ru onto the SBA-16 type silica is confirmed
by TEM images.
Low-temperature N2 adsorption/desorption measurements
The low-temperature nitrogen adsorption/desorption is used for characterization of
porous materials. On the basis of the isotherms obtained it is possible to determine the surface
area, pore volume, pore diameter and pore size distribution. Figure 2 presents the low-
temperature nitrogen adsorption/desorption isotherms for all samples obtained. The shape of
isotherms is characteristic of all mesoporous materials and is labelled as IVa according to
IUPAC classification [32, 33]. The isotherms showed one hysteresis loop. For the samples SBA-

16/Ru, SBA-16/Pd and SBA-16/Pt the hysteresis loop was of similar size, which indicated
similar total pore volume, and appeared in the relative pressure range p/p0=0.45-0.7.
700
SBA-16/Pt
600
SBA-16/Pd
500
400
300
200
100
0
+300
+200
+100
SBA-16/Ru
SBA-16/Nb
0.0
0.2
0.4
0.6
0.8
1.0
Relative pressure p/p0
Figure 2.Isotherms of the SBA-16 mesoporous silica containing different metal atoms.
Table 1 presents the textural parameters of the materials studied. All silicas are
characterized by relatively large surface areas (BET). The largest surface area of 920 m2/g was
found for SBA-16/Nb, while the smallest for SBA-16/Pt (704 m2/g). The other textural
parameters of the silica samples that is pore volume of over 0.5 cm3/gand average pore size
varied from6.3 to 7.4 nm, were very similar. The generally similar textural parameters of all

silicas mean that incipient wetness impregnation had practically no effect on the quality of the
silicas (structure and textural properties).
Table 1. Structure and textural properties of all catalysts.
Surface area (BET)
Total pore volume
[cm3/g]
Pore size (BJH ads.)
[nm]
Catalysts
[m2/g]
920
SBA-16/Nb
SBA-16/Ru
SBA-16/Pd
SBA-16/Pt
0.6
0.6
0.5
0.5
7.4
6.3
6.4
6.3
769
743
704
TEM images
The TEM images provided the information on the degree of structural ordering and the
presence of transition metals in the samples. As follows from the TEM images presented in
Table 2, all synthesized samples show high structural ordering, which has been also indicated by
XRD results. The dark points visible in the TEM images are the evidence of transition metal
presence in the samples, which confirms the effectiveness of incipient wetness impregnation
method. The introduced transition metals show good dispersion and their clusters have similar
sizes within a given sample.
Table 2. TEM images of the SBA-16 silica containing various transition metal atoms
(a-Pt, b-Pd, c-Ru, d-Nb).

b)
a)
20 nm
20 nm
d)
c)
20 nm
20 nm
The results of the SEM-EDX analysis show homogeneous distribution of the introduced metal.
The metal content was presented in Table S1 (see Figure S1 and Table S1 in supporting
information). Thermal stability of the samples were described in supporting information. All the
materials are stable at the temperature applied for HDO.
The results of phenol HDO reaction
It is known from literature that phenol molecules under elevated pressure and temperatures (the
conditions typical of hydrodeoxygenation) undergo different transformations, e.g. hydrogenation,
dehydration, demethoxylation, demethylation and methylation [34, 35].The type of reaction

products depends not only on the reaction conditions but also on the type of catalyst used. By
chromatographic methods the following products of HDO of phenol: cyclohexene, 1-
methoxycyclohexene, cyclohexanol, 1-methoxy-2-hexene and 2,4-dimethylhexane were
identified. The products labelled as “other” are the undesirable products of phenol addition,
mainly naphthalene derivatives. Figure 4 presents a scheme illustrating the possible
transformations of phenol molecules in the process performed. On the basis of the identified
products of HDO reaction of phenol, we proposed two pathways of transformations (Fig. 4).
According to the first pathway, at first the aromatic ring is hydrogenated, which leads to
cyclohexanol formation, then cyclohexanol is dehydrated to cyclohexene. The second pathway
leads to 1-methoxycyclohexene as a result of partial hydrogenation of the aromatic ring and
attachment of a methyl group to the oxygen atom. Then, the C-C is broken, the cyclic character
is lost and 1-methoxy-2-hexene is produced. Finally, after demethoxylation and attachment of
two methyl groups, 2,4-dimethylhexane is obtained. It is important to stress that such mechanism
can be observed only in the case of Brønsted acid sites. It has been largely recognized that the
transmethylation reaction is induced by a proton that dissociates from the acid site and launches an
electrophilic attack on the reactant [34]. The domination of this pathway may be related to the
character of transition metal and acidity of the support used as the energy needed for
hydrogenation of aromatic ring is lower than that needed to break the bond between the carbon
atom from the aromatic ring.

Figure 4. Scheme of the possible routes of phenol hydrodeoxygenation.
It is interesting to note that kinetic profiling revealed ring hydrogenation as the dominant
pathway during the first hour of reaction. Afterwards, slower C=C hydrogenation versus C=O
hydrogenation occurs. Further kinetic studies are currently underway to elucidate the rate-
determining step in phenol HDO, in addition to the impact of metal loading, and the selection of
phenolic substrate (e.g. guaiacol), in order to optimize the yield of products and establish the
generic applicability of supported SBA-16 in biooil HDO.
Figures 5-8 illustrate the phenol conversion depending on the catalyst and reaction conditions
applied. Tables 3-6 present the reaction products and selectivities of their formation.

SBA-16/Nb
100
80
60
40
20
0
2.5 MPa
4 MPa
6 MPa
90
110
130
Temperature [°C]
Figure 5. Conversion of phenol over SBA-16/Nb catalyst under different conditions.
Table 3. Product distribution for phenol HDO over SBA-16/Nb catalyst under different
conditions.
Selectivity [%]
Temperature
[°C]
Pressure
[MPa]
Catalyst
0.0
0.0
0.0
11.6
9.9
0.0
0.0
0.0
83.1
83.3
82.8
0.0
0.0
0.0
5.3
6.7
6.1
2.5
4
SBA-16/Nb
90
11.1
6

0.0
0.0
0.0
7.8
6.0
0.0
0.0
0.0
92.2
94.0
71.3
0.0
0.0
0.0
0.0
0.0
2.5
4
110
12.0
16.7
6
0.0
0.0
0.0
11.5
10.3
8.2
0.0
0.0
0.0
78.9
83.7
81.6
0.0
0.0
0.0
9.6
6.0
2.5
4
130
10.2
6
As follows from Figure 5, the sample of SBA-16 impregnated with niobium is little
active in HDO of phenol. The maximum phenol conversion was 6% for the process run at 130°C
and hydrogen pressure of 6 MPa. At such a small conversion, besides the chemical compounds
obtained as a result of phenol addition (denoted as other), two products were observed: 1-
methoxycyclohexene (maximum selectivity of 12%) and 1-methoxy-2-hexene (maximum
selectivity of 94%) which was the main product. No formation of cyclohexene, cyclohexanol or
2,4-dimethylhexane was detected. On the basis of the products of HDO reaction of phenol it can
be inferred that the second pathway of transformations was realized. The increase in temperature
and hydrogen pressure had no (or a little) effect on the process.

SBA-16/Ru
2.5 MPa
4 MPa
6 MPa
100
80
60
40
20
0
90
110
Temperature [°C]
130
Figure 6. Conversion of phenol over SBA-16/Ru catalyst.
Table 4. Product distribution for phenol HDO over SBA-16/Ru catalyst under different
conditions.
Selectivity [%]
Temperature
[°C]
Pressure
[MPa]
Catalyst
2.3
1.1
0.6
9.5
16.6
1.9
22.7
32.0
10.4
26.1
6.7
37.5
43.6
62.2
1.9
0.0
2.5
4
90
SBA-16/Ru
24.9
0.00
6

1.0
0.9
0.9
0.7
0.7
0.4
38.3
22.9
3.8
3.4
2.6
0.2
56.4
72.8
94.7
0.2
0.1
0.0
2.5
4
110
6
2.5
1.4
1.5
0.3
0.7
0.2
3.2
3.9
3.9
0.0
2.6
0.4
93.9
90.9
93.9
0.1
0.5
0.1
2.5
4
130
6
When the HDO of phenol is catalyzed by SBA-16/Ru, at all temperatures and pressures
applied, the main reaction product was 2,4-dimethylhexane. With increasing temperature and
hydrogen pressure, the conversion of phenol increased (Fig. 6). Full phenol conversion was
obtained for the reaction performed at 110°C and hydrogen pressure of 6 MPa and adversary all
reactions carried out at 130°C.When the reaction was performed at 90°C, besides the main
product of 2,4-dimethylhexane relatively large amounts of cyclohexanol (maximum selectivity
32%)and 1-methoxy-2-hexene (maximum selectivity 26.1%) were formed. At a temperature by
20°C higher, the catalyst was selective towards the main product and cyclohexanol (maximum
selectivity 38.3%).At 130°C, the formation of 2,4-dimethylhexane was observed with almost
94% selectivity.

SBA-16/Pd
2.5 MPa
4 MPa
6 MPa
100
80
60
40
20
0
90
110
130
Temperature [°C]
Figure 7. Conversion of phenol over SBA-16/Pd catalyst.
Table 5. Product distribution for phenol HDO over SBA-16/Pd catalyst under different
conditions.
Selectivity [%]
Temperature
[°C]
Pressure
[MPa]
Catalyst
0.2
0.8
0.5
1.4
0.5
0.5
4.1
2.9
2.4
33.7
0.0
51.3
73.8
76.6
9.3
2.5
4
22.0
19.9
SBA-16/Pd
90
0.1
6

1.0
1.2
1.0
1.0
0.2
0.9
4.4
2.8
3.9
0.0
0.0
0.2
67.0
75.1
72.5
26.6
20.7
21.5
2.5
4
110
6
1.5
1.6
1.9
0.5
0.5
0.5
2.7
3.2
2.9
2.6
2.8
1.3
81.8
68.2
83.7
10.9
23.7
9.7
2.5
4
130
6
The palladium catalyst was even more active in HDO of phenol than the ruthenium one,
as illustrated in Fig. 7. The main reaction product was 2,4-dimethylhexane, similarly as in the
presence of SBA-16/Ru. Over the palladium catalyst in all temperature and hydrogen pressure
variants 100% of phenol conversion was obtained. No significant influence of temperature and
hydrogen pressure on the course of the process was noted. The catalytic system applied led to
formation of phenol addition products (labelled as “other”) in the amounts reaching almost 27%
at the expense of smaller amounts of 2,4-dimethylhexane.

SBA-16/Pt
2.5 MPa
4 MPa
6 MPa
100
80
60
40
20
0
90
110
130
Temperature [°C]
Figure 8. Conversion of phenol over SBA-16/Pt catalyst.
Table 6. Product distribution for phenol HDO over SBA-16/Pt catalyst under different
conditions.
Selectivity [%]
Temperature
[°C]
Pressure
[MPa]
Catalyst
17.4
20.9
20.4
1.3
0.8
0.8
4.7
3.2
4.1
0.0
0.0
0.0
76.6
75.1
74.6
0.0
0.0
0.1
2.5
4
SBA-16/Pt
90
6

17.3
19.9
19.3
0.8
0.6
0.7
3.7
3.6
3.2
0.0
0.1
0.0
77.4
75.6
76.6
0.8
0.2
0.2
2.5
4
110
6
17.3
12.7
10.2
0.2
1.0
0.4
3.8
5.2
5.0
0.1
0.1
0.2
78.4
80.7
84.2
0.2
0.3
0.0
2.5
4
130
6
Fig. 6 presents the results of the reaction catalyzed by SBA-16/Pt. The main product was
also 2,4-dimethylhexane. In the presence of this catalyst some considerable amounts of
cyclohexene were formed, for the reaction at 90°C and at hydrogen pressure of 4 MPa, the
selectivity to cyclohexene was 21%. Thanks to the use of platinum as the active phase of the
catalyst, a high degree of phenol deoxygenation and hydrogenation was achieved. In almost all
temperature and pressure variants 100% phenol conversion was obtained. Similarly as in the
presence of palladium catalyst, no effect of temperature and hydrogen pressure on the course of
the process was noted.
To summarize, all the catalysts were active in the HDO of phenol and the most active
catalysts were those containing Pd and Pt. It is worthy to stress that for those catalysts methyl
group transfer and C-C bond cleavage were predominant. Contrary to that are numerous
investigations, where HDO of phenol undergoes two main parallel routes with products
presented in Table 7. The first route is direct deoxygenation (DDO) that leads to formation of
benzene by the cleavage of C-O bond. The second is hydrogenation in which the aromatic ring is
hydrogenated to cyclohexanol. Subsequent hydrogenation of benzene or deoxygenation of

cyclohexanol follows, leading to the formation of cyclohexane. In our case the main reaction
product was an aliphatic hydrocarbon (not an aromatic hydrocarbon) and higher phenol
conversion rates were obtained under milder temperature and pressure conditions.
Table 7. Reaction conditions, phenol conversion and product distribution for phenol HDO over
different catalysts (literature data)
H2
Temperature
[°C]
Selectivity Conversion
pressure
Catalyst
Main product
Lit.
[%]
[%]
[MPa]
SiO2/Pd
Nb2O5/Pd
cyclohexanone
benzene
91.6
80.2
84.1
63.0
90.0
44.0
15.8
6.6
300
0.1
[35]
Al2O3/Pd
300
280
350
200
0.1
1
cyclohexanone
cyclohexane
benzene
7.5
[36]
[37]
[38]
[39]
MCM-41/Pd
Mo2C/TiO2
Ni/HZSM-5
80.0
65.0
9.0
2.5
5
cyclohexanone
Conclusions
The results of our experiment comprising the synthesis, physicochemical characterization
and catalytic application of ordered mesoporous silica as supports of transition metals, permit
drawing the following conclusions.
1. All synthesized materials are characterized by good textural and structural
parameters, which has been established on the basis of XRD, TEM and low-
temperature N2sorption measurements, SEM/EDX, XPS measurements, TG analysis
and H2-TPR.

2. All synthesized materials are active in hydrodeoxygenation of phenol.
3. The type of metal on the surface of the silica support has direct impact on the degree
of phenol conversion, type and amount of the reaction products. The activity of the
catalysts obtained in HDO of phenol increases in the following order SBA-16/Nb <
SBA-16/Ru < SBA-16/Pd < SBA-16/Pt.
4. The main product of the reaction, irrespectively of the reaction conditions was the
branched hydrocarbon 2,4-dimethylhexane, characterized by the H/C ratio greater
than that of phenol and with no oxygen in its structure.
5. The values of temperatures and pressures applied had impact on the degree of phenol
conversion only when the reaction was performed over the catalyst SBA-16/Ru.
6. The values of temperatures and pressures applied had impact on the type and amounts
of the reaction products in the presence of all catalysts applied.
Acknowledgments
National Science Centre is kindly acknowledged for the financial support (project no: DEC-
2013/10/M/ST5/00652).
References
(1) Yujie, S.; Zhang, P.; Sua, Y. Renew. Sust. Energ. Rev., 2015, 50, 991.
(2) Zhong, W.; An, H.; Shen, L.; Fang, W.; Gao, X.; Dong, D. Energ. Policy2017, 100, 365.
(3) McKendry, P. Bioresource Technol.2002, 83, 37.
(4) He, Z.; Wang, X. Catal. Sust. Energ. 2012, 1, 28.
(5) Vassilev, S. V.; Vassileva, C. G.; Vassilev, V. S. Fuel, 2015, 158, 330.
(6) Liao, Y.; Liu, Q.; Wang, T.; Long, J.; Ma, L.; Zhang, Q. Green Chem.2014, 16, 3305.

(7) Mohan, D.; Pittman, C. U.; Steele, P. H. Energ. Fuel 2006, 20, 848.
(8) Mu, W.; Ben, H.; Du, X.; Zhang, X.; Hu, F.; Liu, W.; Ragauskas, A. J.; Deng, Y.
Bioresource Technol.2014, 173, 6.
(9) Kan, T.; Strezov, V.; Evans, T. J. Renew. Sust. Energ. Rev.2016, 57, 1126.
(10) Sharifzadeh, M.; Richard, C.J.; Liu, K.; Hellgardt, K.; Chadwick, D.; Shah, N. Biomass
Bioenerg. 2015, 76, 108.
(11) Sharifzadeh, M.; Richard, C. J.; Liu, K.; Hellgardt, K.; Chadwick, D.; Shah, N. Biomass
Bioenerg.2015, 76, 108.
(12) Li, X.; Chen, G.; Liu, C.; Ma, W.; Yan, B.; Zhang, J. Renew. Sust. Energ. Rev.2017, 71,
296.
(13) Bu, Q.; Lei, H.; Zacher, A. H.; Wang, L.; Ren, S.; Liang, J.; Wei, Y., Liu, Y.; Tang, J.;
Zhang, Q.; Ruan, R. Bioresource Technol. 2012, 124, 470.
(14) Shafaghat, H.; Rezaei, P. S.ü; Wan Daud, W. M. A. J. Ind. Eng. Chem. 2016, 35, 268.
(15) De, S.; Saha, B.; Luque, R. Bioresource Technol.2015, 178, 108.
(16) Arun, N.; Sharma, R. V.; Dalai, A. K. Renew. Sust. Energ. Rev.2015, 48, 240.
(17) Liu, Y.; Chen, L.; Wang, T.; Zhang, Q.; Wang, C.; Yan, J.; Ma, L. ACS Sustain. Chem.
Eng.2015, 3, 1745.
(18) Byun, J.; Han, J. Bioresource Technol., 2016, 211, 360.
(19) Jin, S.; Xiao, Z.; Li, C.; Chen, X.; Wang, L.; Xing, J.; Li, W.; Liang, C. Catal. Today 2014,
234, 125.
(20) Patel, M.; Kumar, A.Renew. Sust. Energ. Rev., 2016, 58, 1293.
(21) Yao, G.; Wu, G.; Dai, W.; Guan, N.; Li, L. Fuel, 2015, 150, 175.

(22) Güvenatam, B.; Kurşun, O.; Heeres, E. H. J.; Pidko, E. A.; Hensen, E. J. M. Catal.
Today2014, 233, 83.
(23) Lup, A. N. K.; Abnisa, F.; Daud, W. M. A. W.; Aroua, M. K. J. Ind. Eng. Chem.2017, 56, 1.
(24) Li, X.; Luo, X.; Jin, Y.; Li, J.; Zhang, H.; Zhang, A.; Xie, J. Renew. Sust. Energ. Rev.2018,
82, 3762.
(25) Nava, R.; Pawelec, B.; Castaño, P.; Alvarez- Galván, M. C.; Loricera, C. V.; Fierro, J. L. G.
Appl. Catal. B-Environ.2009, 92, 154.
(26) Kumar, P.; Guliants, V. V. Micropor. Mesopor. Mat.2010, 132, 1.
(27) Bhanja, P.; Bhaumik, A. Fuel2016, 185, 432.
(28) Ghampson, I.T.; Sepúlveda, C.; Garcia, R.; Fierro, J. L. G.; Escalona, N.; DeSisto, W. J.
Appl. Catal. A-Gen. 2012, 51, 435.
(29) Nowak, I.; Jaroniec, M. Stud. Surf. Sci. Catal.2007, 165, 69.
(30) Grudzien, R.M.; Grabicka, B.E.; Jaroniec, M. Appl. Surf. Sci.2007, 253, 5660.
(31) Hoffmann, F.; Cornelius, M.; Morell, J.; Fröba, M. Angew. Chem. Int. Edit.2006, 45, 3216.
(32) Thommes, M.; Kaneko, K.; Neimark, A. V.; Olivier, J. P.; Rodriguez-Reinoso, F.;
Rouquerol, J.; Sing, K. S. W. Pure. Appl. Chem.2015, 87, 1051.
(33) Zhang, J.; Fidalgo,B.; Kolios, A.; Shen, D.; Gu, S. Sust. Energy Fuels. 2017, 1, 1788.
(34) Sanna, A.; Vispute, T.P.; Huber, G.W. Appl. Catal. B-Environ. 2015, 165, 446.
(35) Barrios, A. M.; Teles, C. A.; Souza, P. M.; Rabelo-Neto, R. C.; Jacobs, G.; Davis, B. H.;
Borges, L. E. P.; Noronha, F. B. Catal. Today2018, 302, 115.
(36) Souza, P.M.; Rabelo-Neto, R.C.; Borges, L.E.P.; Jacobs, G.; Davis, B.H.; Graham, U.M.;
Resasco, D.E.; Noronha, F.B. ACS Catal.2015, 5, 7385.
(37) Zeng, Y.; Wang, Z.; Lin, W.; Song, W.; Christensen, J.M.; Jensen, A.D. Catal.
Commun.2016, 82, 46.

(38) Boullosa-Eiras, S.; Lodeng, R.; Bergem, H.; Stöcker, M.; Hannevold, L.; Blekkan, E.A.
Catal. Today, 2014, 223, 44.
(39) Zhao, C.; Kasakov, S.; He, J.; Lercher, J.A. J. Catal.2012, 296, 12.