CHEMICAL ENGINEERINGTRANSACTIONS 
 

VOL. 70, 2018 

A publication of 

 

The Italian Association 
of Chemical Engineering 
Online at www.aidic.it/cet 

Guest Editors:Timothy G. Walmsley, Petar S.Varbanov, Rongxin Su, Jiří J.Klemeš 
Copyright © 2018, AIDIC ServiziS.r.l. 

ISBN978-88-95608-67-9; ISSN 2283-9216 

The Liquid Phase Catalytic Hydrogenation of the Furfural to 

Furfuryl Alcohol 

Kseniya Salnikovaa,b, Valentina Matveevaa,b,*, Alexey Bykova, Galina Demidenkoa, 

Irina Shkilevaa, Esther Sulmana 

aTver State Technical Univ., Dept. Of Biotechnology and chemistry, A.Nikitin str., 22, 170026 Tver, Russia 
bTver State Univ., Regional technological centre, Zhelyabova str., 33, 170100 Tver, Russia 

 matveeva@science.tver.ru 

The results of the study of palladium catalysts in the selective hydrogenation of furfural to furfural alcohol are 

presented. A comparison of the properties of palladium catalytic systems prepared on different supports 

(aluminium oxide, hypercrosslinked polystyrene and magnetite/hypercrosslinked polystyrene) is carried out. It 

is shown that the nature of the support has a significant impact on both the morphology of the catalyst and its 

activity in the selective hydrogenation of furfural. The most effective catalyst was magnetically recoverable 3 % 

Pd/Fe3O4/HPS, in the presence of which the conversion of furfural was> 95% with selectivity for furfuryl alcohol> 

94 %. 

1. Introduction 

Increasing interest to biomass as a source of chemicals and energy has recently arisen due to the limited fossil 

fuel resources and the demand for new clean chemical processes (Halilu et al., 2016). The research to develop 

alternative liquid transport fuels has increased considerably in recent years influenced by the implementation of 

legislation and directives on alternative energy. To achieve these aims in an ethical, environmentally sustainable 

and economical manner the use of lignocellulosic biomass or agri-waste for the production of second generation 

biofuels is proposed (Taylor et al., 2016). Chemicals derived from biomass have attracted a considerable interest 

in the recent years (Climent et al., 2014). The production of biofuels from hemicellulose requires acid hydrolysis 

to open the biomass structure giving large quantities of xylose (Paulsen et al., 2013). The synthesis of furfural 

as a by-product of this biofuel production process has developed an additional important research area 

(O’Driscoll et al., 2017). Furfural is one of the key derivatives which can be obtained from renewable biomass 

for the production of different important fine chemicals (Hu et al., 2012). 

Selective hydrogenation of furfural has attracted much attention for the production of furfuryl alcohol, methyl 

furan, tetrahydrofurfuryl alcohol and others (Figure 1). Furfuryl alcohol is widely used in chemical industry, mainly 

for the production of special resins, polymers and coatings on their basis, which are resistant to acids, alkalies 

and various solvents. In addition, furfuryl alcohol is employed as diluents for epoxy resins and as a solvent for 

phenol formaldehyde resins and poorly soluble pigments. In the organic synthesis, furfuryl alcohol is a feedstock 

for the production of tetrahydrofurfuryl alcohol and 2,3-dihydropyranand an intermediate for the synthesis of 

lysine, vitamin C, various lubricants and plasticizers. There are two ways of producing furfuryl alcohol through 

hydrogenation of furfural, gas phase hydrogenation and liquid phase hydrogenation (Nagaraja et al., 2007). In 

industry, furfuryl alcohol is obtained by catalytic hydrogenation of furfural in a liquid or vapor phase (Zeisch, 

2000). The liquid-phase process is carried out with copper chromite systems as the catalysts. The main 

disadvantage of copper-chromite catalysts is their toxicity caused by the presence of chromium oxides, which 

allows considering such catalysts as environmental pollutants (Taylor et al., 2016).  

In the case of liquid-phase hydrogenation, the reaction conditions are milder and it is possible to use both 

homogeneous and heterogeneous catalysts based on mono- (Pd (Aldosari et al., 2016), Pt (Chen et al., 2016), 

Ru (Huang et al., 2007), Ni (Li et al., 2016), Cu (Maligal-Ganesh et al., 2016)) and bimetals (Pd-Ni (Merlo et al., 

2011), Pd-Ir, Pd-Ru (Nagaraja et al., 2003), Pt- Sn (Wu et al., 2005)). Depending on the process conditions, 

                                

 
 

 

 
   

                                                  
DOI: 10.3303/CET1870064 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Please cite this article as: Salnikova K., Matveeva V., Bykov A., Demidenko G., Shkileva I., Sulman E., 2018, The liquid phase catalytic 
hydrogenation of the furfural to furfuryl alcohol , Chemical Engineering Transactions, 70, 379-384  DOI:10.3303/CET1870064   

379



namely the type of catalyst and the nature of the solvent, furfural hydrogenation proceeds in various directions 

and with the formation of a large number of products. Thus, for example, Yu et al. (2011) in the case of 

hydrogenation of furfural in the aqueous phase in the presence of Co/TiO2 noted the formation of such by-

products as pentadioles, pentanols, hydroxycyclopentanone, etc. When using alcohols (methanol, ethanol, 

isopropanol), esterification products and aldol condensation: isopropyl-furfuryl ether, 2-furaldehyde diisopropyl 

acetal (Taylor et al., 2016), 2-furaldehyde dimethyl acetal (Fulajtárova et al., 2015), 2-furaldehyde diethyl acetal 

(Lee et al., 2015) are noted as the reaction medium. 

By varying the conditions for hydrogenation of furfural (pressure, temperature, etc.), it is possible to regulate the 

selectivity for one or another product. This study is devoted to the selection of the catalytic system and process 

conditions for achieving maximum selectivity for furfuryl alcohol. 

O

O

O

OH

Furfural
(FF)

Furfural Alcohol
(FA)

O

O

H2
O

OH

H2

O O
H2  H2

OH

ButanolTetrahydrofuran
(THF)

Furan

H2

Tetrahydrofurfural Tetrahydrofurfuryl
        Alcohol
       (THFA)

H2

H2

 
   

 

Figure 1: The scheme of catalytic hydrogenation of the furfural 

2. Experimental 

2.1 Materials 

As the support of the palladium catalyst, the hypercrosslinked polystyrene (HPS) of Macronet MN 270/3860 

type 2/100 (designation MN-270) was purchased from Purolite Int., (U.K.) and purified by rinsing with water and 

drying in vacuum. Palladium (II) chloride (PdCl2, 99%), Iron (III) chloride hexahydrate (FeCl3 6Н2О, 98 %), 

aluminium oxide (Al2O3, mesoporous, 60 micrometers, for chromatography) were purchased at Sigma-Aldrich. 

Furfural (99 %), furfuryl alcohol (98 %), and i-propanol (≥ 99.5 %) were purchased from Sigma-Aldrich and used 

without purification. 

2.2 Synthesis of catalysts  

The investigated palladium catalysts (Nemygina et al., 2016) were prepared by the method of impregnation 
according to the moisture capacity were described in previous works (Sulman et al., 2016). Aluminium oxide 
and hypercrosslinked polystyrene of the MN-270 type were used as a carrier. Based on the calculated quantities 
of PdCl2 solutions of precursors were prepared, which were impregnated with mesoporous carriers. Magnetically 
recoverable support (Fe3O4/HPS) was synthesized by impregnation of FeCl3 solution, followed by alkali 
treatment. The following catalysts were prepared: 3% Pd/Al2O3, 3 % Pd/HPS and 3 % Pd/Fe3O4/HPS (here 3 
% is the calculated palladium content, in parentheses precursor). 

2.3 Method for hydrogenation of furfural 

Hydrogenation of furfural was carried out in a batch steel batch reactor of the Series 5000 Multiple Reactor 

System (Parr Instruments). Catalyst, furfural and propanol-2 were introduced into the reactor. The reactor was 

purged with nitrogen. After the reactor was heated to operating temperature, hydrogen was supplied. The 

380



hydrogenation process was carried out with continuous stirring (mixing rate 1000 rpm). During the reaction, 

samples of the reaction medium were taken for analysis. The time of one experiment was 240 minutes. 

2.4 Gas chromatography method 

Analysis of the reaction mass was carried out by gas chromatography (gas chromatograph "Crystallux-4000M", 

OOO NPF "Meta-Chrom", Yoshkar-Ola, Republic of Mari El) in the temperature programming mode according 

to the program: column temperature 50 °С, detector 200 °С, the evaporator 120 °С. Chromatograms were 

processed in the "NetChrom" program. Furfural (starting material) - and products of the main and intermediate 

reactions - tetrahydrofuran, furfuryl alcohol were identified; tetrahydrofurfuryl alcohol. 

The conversion of furfural and furfuryl alcohol selectivity were calculated using the Eq (1) and Eq(2): 

Conversion, % = 
n𝐹𝐹
0 −𝑛𝐹𝐹

𝑠

𝑛𝐹𝐹
0 ∗ 100   (1) 

Selectivity, % = 
n𝐹𝐴

𝑛𝐹𝐹
0 −n𝐹𝐹

𝑠 ∗ 100   (2) 

n𝐹𝐹
0  - initial moles of furfural 

𝑛𝐹𝐹
𝑠  - moles of furfural in sample 

n𝐹𝐴 - moles of furfuryl alcohol 

2.5 The method of low-temperature adsorption of nitrogen 

The specific surface area, pore size distribution of the supports and the Pd-containing catalysts were 

investigated by low-temperature nitrogen adsorption using BECMAN COULTERTM SA 3100TM (Coulter 

Corporation, Miami, Flor-ida), BECMAN COULTERTM SA-PREPTM (Coulter Corporation, Miami, Florida), and 

electronic balance GX-200 (A&D Company, Limited, Tokyo, Japan). The following analysis conditions were 

used: t = -196 °C, relative pres-sure 0.9814 (for the pores less than 100 nm), PSD (ADS) profile. 

2.6 X-ray fluorescence analysis  

X-ray fluorescence analysis (XRF) was performed to determine the palladium content of the catalysts under 

study. A VRA-30 spectrometer from “Zeiss Jena” with a molybdenum anode was used, the crystal analyzer was 

a LiF and SZ detector. Samples (for analysis and comparison) were prepared by mixing 1 g of polystyrene with 

10-20 mg of the substance. The measurement time (analysis) is 10 s.  

2.7 Atomic-absorption spectrometry 

To study the catalyst for heterogeneity (stability), an analysis was carried out for the content of palladium in the 

liquid phase using an atomic absorption spectrometer MGA-915 (NPF AP “Lumeks”, Russia).  

2.8 Transmission electron microscopy 

Electron-transparent specimens for transmission electron microscopy (TEM) were prepared by placing a drop 

of a sample suspension onto a carbon-coated Cu grid. Images were acquired at an accelerating voltage of 80 

kV on a JEOL JEM1010 transmission electron microscope. 

3. Results and discussion 

The results of the elemental analysis (see Table 1) showed that the palladium content in the catalysts under 

study is practically the same as calculated. According to the data of atomic absorption spectrometry, the 

synthesized heterogeneous palladium systems are stable against leaching, and the active phase does not wash 

out. From this it follows that hydrogenation of furfural proceeds on the surface of a heterogeneous catalyst.  

Table 1: The main characteristics of palladium catalysts (according to BET, RFA and TEM) 

Sample  Specific  

surface, m2/g 

Specific surface  

of micropores, m2/g 

The size of  

palladium particles, nm  

Content of  

palladium, % 

3 % Pd/Al2O3  59 0 - 2.87 

3 % Pd/HPS  816 94 25 - 30 2.93 

3 % Pd/Fe3O4/HPS 450 290 25 - 30 2.78 

 

In early studies (Stepacheva et al., 2016), it was shown that the palladium particle size synthesized in the HPS 

matrix is 25-30 nm. TEM result for 3 % Pd/Fe3O4/HPS showed that the average diameter of palladium particles 

is 27.8 nm (Figure 2). The introduction of Fe3O4 magnetic particles into the HPS matrix did not affect the 

formation and size of palladium particles. 

381



(a)  (b)

Average=27.8 nm

Nanoparticle diameter (nm)

10 20 30 40 50

F
r
e
q

u
e
n

c
y

0

10

20

30

40

50

 

Figure 2: a) TEM image of 3% Pd/Fe3O4/HPS catalyst. b) Pd particle-size distribution for 3% Pd/Fe3O4/HPS. 

Studies of the texture of palladium catalysts by low-temperature adsorption of nitrogen have shown that the 

surface areas of the samples vary significantly (Table 1). The minimum surface area was found in a sample of 

3 % Pd/Al2O3) (59 m2/g) in comparison with catalysts on the basis of the HPS. The catalyst surface area of 3% 

Pd/ HPS was 816 m2/g with an insignificant microporous surface area (94 m2/g) (Table 1). The introduction of 

magnetite Fe3O4 (catalyst 3 % Pd/Fe3O4/HPS) into the porous matrix of HPS leads to decrease in the surface 

area almost twice (450 m2/g) (Table 1). For a sample 3% Pd/Fe3O4/HPS, the specific surface of micropores 

increases to 290 m2/g (which is about 60 % of the total specific surface). It is likely that this is due to the formation 

of magnetite particles in the HPS pores. 

The catalytic properties of the samples of 3 % Pd/Al2O3, 3 % Pd/HPS, 3 % Pd/Fe3O4/HPS were studied in the 

selective hydrogenation of furfural to furfuryl alcohol. Optimal conditions of the furfural hydrogenation have been 

determined:  a temperature of 120 °C and a hydrogen pressure of 6.0 MPa. Propanol-2 was used as the solvent.  

The dependence of the conversion of furfural on time for the prepared palladium catalysts is shown in Figure 3 

(a).  The highest conversion of furfural (95.6 % and 95.3 %) over the observed reaction period was achieved in 

the presence of an HPS catalysts (3 % Pd/Fe3O4/HPS and 3% Pd/HPS accordingly), a lower value (87.0 %) 

was obtained on a 3 % Pd/Al2O3 catalyst. The specific surface of the classical carrier Al2O3 is small in 

comparison with that of the HPS, which, apparently, determines the smaller number of active sites and, 

accordingly, the lower activity of the catalyst on Al2O3. 

It should be noted that the selectivity of the process for furfural alcohol for catalyst on the Al2O3 support is not 

very high (73.5 %). At the same time, selectivity of the process for furfural alcohol was significantly higher for 

samples based on HPS: 91.4% for the catalyst 3% Pd/HPS and 94.3 % for 3 % Pd/Fe3O4/HPS accordingly 

(Figure 3 (b)). 

Time, min.

0 50 100 150 200 250

C
o
n

v
e
r
si

o
n

, 
%

0

20

40

60

80

100

3% Pd/HPS

3% Pd/Al2O3

3% Pd/Fe3O4/HPS

 
Time, min.

0 50 100 150 200 250

S
e
le

c
ti

v
it

y
, 
%

0

20

40

60

80

100

3% Pd/HPS 

3% Pd/Al2O3 

3% Pd/Fe3O4/HPS

 

Figure 3: Dependences of the conversion of furfural (a) and the selectivity of furfuryl alcohol (b) on the reaction 

time in the presence of palladium catalysts  

а b 

382



In this case, it may indicate that the active centers are formed differently for Al2O3 and HPS. As by-products, 

hydrogenation products of furfuryl alcohol, 2-methylfuran and tetrahydrofuran, have been identified. The 

obtained results testify to the influence of the nature of the support on its catalytic properties. 

In order to evaluate the catalyst stability in the repeated use, ten successive experiments of the furfural 

hydrogenation were carried out in the optimal conditions discussed above.  

Figure 4a shows that catalysts based on HPS are more stable in comparison Al2O3 support. Catalysts based on 

HPS lose only 1-3 % of its activity after ten catalytic cycles, while 3 % Pd/Al2O3 loses 14 %. Palladium catalysts 

based on magnetite and HPS (3 % Pd/Fe3O4/HPS) showed higher activity and selectivity in the process for the 

hydrogenation of furfural to furfuryl alcohol. Moreover, it is necessary to note the advantage of this catalyst in-

easy separation from the reaction mixture by magnet (Figure 4b). 

Such a high activity and selectivity showed Pd-containing magnetite nanoparticles stabilized by 

polyphenylquinoxaline, as presented in the work of the Alibegovic and co-workers (Alibegovic et al., 2017). 

Number of cycles

1 2 3 4 5 6 7 8 9 10

C
o

n
v
e

rs
io

n
, 
%

60

70

80

90

100

3% Pd/HPS

3% Pd/Al
2
O

3

3% Pd/Fe
2
O

3
/HPS

 

 

 
 

Figure 4: (a) the Pd catalyst stability in ten cycles, (b) separation of the 3% Pd/Fe3O4/HPS catalyst from the 

reaction mixture by a magnet 

4. Conclusions 

Studies and catalytic tests of palladium catalysts in a complex multistage process of furfural hydrogenation 

involving the main reaction for the formation of the desired product - furfuryl alcohol and side reactions of 

hydrogenation were carried out. Samples of palladium catalysts were prepared on different supports. The 

supports were aluminium oxide, hypercrosslinked polystyrene and magnetite/hypercrosslinked polystyrene. 

Studies have shown that the nature of the support has a significant effect on the conversion of furfural and the 

selectivity for furfuryl alcohol. The most effective catalyst was magnetically recoverable 3 % Pd/Fe3O4/HPS, in 

the presence of which the conversion of furfural was> 95% with selectivity for furfuryl alcohol> 94 %. 

Acknowledgements 

The authors thank the Russian Science Foundation (project 17-19-01408) and the Russian Foundation for Basic 

Research (grant 18-08-00468) for financial support. The authors thank Dr. Lyudmila Bronstein (Department of 

Chemistry, Indiana University, United States) for help with TEM studies. 

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