Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
Catalysis Communications 17 (2012) 126–130
Contents lists available at SciVerse ScienceDirect
Catalysis Communications
Short Communication
Continuous hydrogenation of hydroquinone to 1,4-cyclohexanediol over alkaline
earth metal modified nickel-based catalysts
⁎
Guoyi Bai , Fei Li, Xinxin Fan, Yalong Wang, Mande Qiu, Zheng Ma, Libo Niu
Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, College of Chemistry and Environmental Science, Hebei University, Baoding, Hebei, 071002, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Effects of different alkaline earth metals (Mg, Ca, Sr) on the nickel-based catalysts for the continuous hydrogena-
tion of hydroquinone were studied, and it was found that the by-products, characterized by GC–MS analysis,
were mainly composed of phenol and cyclohexanol. The conversion of hydroquinone was 99.2% and the selectiv-
ity to 1,4-cyclohexanediol was above 96.7% over a Ni–Sr/γ-Al2O3 catalyst at 160 °C and 2.0 MPa hydrogen
pressure. The high selectivity of the Ni–Sr/γ-Al2O3 catalyst was ascribed to its weak acidity due to the formation
of SrCO3, confirmed from XRD and NH3-TPD characterizations. Moreover, it was proposed that SrCO3 can
disperse and stabilize the active Ni species, making the catalyst stable during the 90 h service life test.
© 2011 Elsevier B.V. All rights reserved.
Received 14 September 2011
Received in revised form 23 October 2011
Accepted 26 October 2011
Available online 4 November 2011
Keywords:
Hydroquinone
Hydrogenation
1,4-Cyclohexanediol
Nickel-based catalyst
Alkaline earth metal modified
1. Introduction
characterized and the results were found to correlate well with their
activities.
1,4-Cyclohexanediol is an important intermediate for the synthesis
of medicinal and liquid crystal materials [1,2]. Traditionally, 1,4-cyclo-
hexanediol was produced mainly by the hydrogenation of hydroqui-
none using Ni/SiO2 [3], Raney Ni [4] or noble metal catalysts [5]. For
example, Adkins and Cramer first reported the synthesis of 1,4-cyclo-
hexanediol from the hydrogenation of hydroquinone over a Ni/SiO2
catalyst, but no data on the catalyst stability were provided [3]. The
reported methods were all batch process and lack of efficiency, and
the catalysts used either caused serious environmental pollution or
were of high cost. Therefore, it is desirable to develop a novel method
for the effective synthesis of 1,4-cyclohexanediol.
Although nickel-based catalysts have been widely used in industry
for the continuous hydrogenation of compounds with phenol structures
[6,7], no work has ever been reported about the continuous hydrogena-
tion of hydroquinone due to its complex structure as well as lacking
more effective and stable catalysts. In this study, we first investigated
the continuous hydrogenation of hydroquinone to 1,4-cyclohexanediol
over nickel-based catalysts. Considering that the acidity of the catalysts
may cause the dehydration of hydroquinone and 1,4-cyclohexanediol
[8–11], the acidic and basic capacities of the catalysts were regulated
by the addition of some basic promoters, such as the alkaline earth
metals (Mg, Ca, Sr). A Ni–Sr/γ-Al2O3 catalyst showed significantly
higher activity and selectivity toward 1,4-cyclohexanediol compared
with other catalysts. The structures of the nickel-based catalysts were
2. Experimental methods
2.1. Catalyst preparation
Unless otherwise stated, all chemicals were purchased from Baoding
Huaxin Reagent and Apparatus Co., Ltd. and were used as received
without further purification. The nickel-based catalysts were prepared
by the co-precipitation method. A typical procedure is as follows. A
solution containing requisite amounts of metal nitrates were added
dropwise to a mixture of Na2CO3 and powder γ-Al2O3 (Xinxiang
Jinsheng New Material Co., Ltd.) at 40 °C. The final pH value was adjust-
ed to 8 with Na2CO3 solution. Then, the co-precipitated mass was
thoroughly washed, filtered, dried at 110 °C for 4 h and calcined at
500 °C for 4 h. The obtained catalysts were designated as Ni/γ-Al2O3,
Ni–Mg/γ-Al2O3, Ni–Ca/γ-Al2O3, and Ni–Sr/γ-Al2O3, respectively.
2.2. Catalyst characterization
The nitrogen adsorption was measured using a Micromeritics Tristar
II 3020 surface area and pore analyzer. X-ray diffraction (XRD) analysis
was carried out on a Y-2000 X-ray diffractometer with Cu Kα radiation.
Scanning electron micrographs (SEM) were obtained on a JEOL JSM-
7500 instrument. H2 chemisorption, temperature programmed reduc-
tion (TPR) and temperature programmed desorption of NH3
(NH3-TPD) were performed using a TP-5000 instrument from Xianquan
Ltd. The X-ray photoelectron spectroscopy (XPS) measurements were
⁎
Corresponding author at: No. 180 Wusi East Road, Baoding City, Hebei 071002, PR
China. Tel.: +86 312 5079359; fax: +86 312 5937102.
1566-7367/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.catcom.2011.10.026