Chinese Chemical Letters  2016, Vol. 27 Issue (7): 1004-1008   PDF    
Low-temperature hydrogenation of maleic anhydride to succinic anhydride and γ-butyrolactone over pseudo-boehmite derived alumina supported metal (metal = Cu, Co and Ni) catalysts
Li Jie, Qian Lin-Ping, Hu Li-Ya, Yue Bin, He He-Yong     
Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University, Shanghai 200433, China
Abstract: The pseudo-boehmite derived alumina supported metal (Cu, Co and Ni) catalysts prepared by the impregnation method were investigated in hydrogenation of maleic anhydride (MA) to succinic anhydride (SA) and γ-butyrolactone. The catalysts were characterized by ICP-AES, N2 adsorption-desorption, XRD, H2-TPR, CO-TPD, dissociative N2O adsorption and TEM and the results showed that the alumina possessed mesoporous feature and the metal species were well dispersed on the support. Compared to Cu/Al2O3 and Co/Al2O3, Ni/Al2O3 exhibited higher catalytic activity in the MA hydrogenation with 92% selectivity to SA and nearly 100% conversion of MA at 140 ℃ under 0.5 MPa of H2 with a weighted hourly space velocity of 2 h-1 (MA). The stability of Ni/Al2O3 catalyst was also investigated.
Key words: Maleic anhydride     Hydrogenation     Succinic anhydride     Nickel    
1. Introduction

Developing highly active catalysts for hydrogenation of maleicanhydride (MA) under low temperature is significant for theproduction of important industrial chemicals [1-3]. The reactionproducts such as succinic anhydride (SA), γ-butyrolactone (GBL), tetrahydrofuran (THF), and 1, 4-butanediol (BDO) are widely usedas solvents or raw materials for polymer synthesis.

Noblemetal-based catalysts, such as Ru/C [2], Pd/SiO2 [4] and Pd/Al2O3 [5], have been reported as effective catalysts in hydrogenationof MA. The reaction is generally carried out at temperature of 100-240 8C and pressure of 0.2-5 MPa and the main products are SA andGBL. Although the noble metal catalysts exhibited good catalyticperformance for the MA hydrogenation, high cost and limitedresource of noble metal restrict their application. Recently, moreattention has been drawn on developing non-noble metal catalysts, such as Cu/SiO2 [6], Co/SiO2 [7], Ni/HY-Al2O3 [8] and Ni/CeO2 [9], generally operated at temperature of 190-210 8C and pressure of0.1-5 MPa. Among these catalysts, Cu-, Co- and Ni-containingcatalysts have shown remarkable catalytic activity.

It is well known that supports generally facilitate the catalystswith high dispersion and stability of the active species [10]. Muchattention has been paid into the selection of suitable catalystsupport for the MA hydrogenation. Various supports, such as CeO2[9], SBA-15 [11], hydroxylapatite [11], MCM-41 [11], TiO2 [12] andAl2O3 [13] have been investigated for the MA hydrogenation to SAand GBL. Among these supports, alumina was widely used andshowed good stability in the hydrogenation of MA [5, 13-16].Pseudo-boehmite is usually employed as the precursor to preparedifferent types of alumina supports [17].

In this work, we reported a novel and simple method to preparepseudo-boehmite derived alumina supported Cu-, Co- and Nicontainingcatalysts (Cu/Al2O3, Co/Al2O3 and Ni/Al2O3) used for thehydrogenation of MA. We aimed to explore the effective catalystfor hydrogenation of MA under low temperature and pressure.

2. Experimental 2.1. Catalyst preparation

The Al2O3 support was obtained through the calcination of pseudo-boehmite (Shangdong City Star Petroleum ChemicalTechnology Co., Ltd.) precursor at 750 ℃ for 3 h as Al2O3 preparedat this temperature has high surface area and large pore volumealong with high crystallinity (Fig. S1 and Table S1 in Supportinginformation). All the catalysts were prepared by the wetimpregnation method. To prepare Ni/Al2O3, 5.6 mL of 0.32 mol L-1 1 aqueous solution of Ni(NO3)2-6H2O was added into a suspensioncontaining 2 g of Al2O3 and 32 mL of H2O. The mixture wasmagnetically stirred for 12 h at room temperature. After evaporationof water at 70 ℃, the sample was dried at 120 ℃ overnight andthen calcined in air at 450 ℃ for 3 h. To prepare Cu/Al2O3 and Co/Al2O3, the same procedure of preparing Ni/Al2O3 was followedexcept using the equimolar of Cu(NO3)2-3H2O and Co(NO3)2-6H2Oinstead, respectively.

2.2. Catalyst characterization

Elemental analysis was performed on a Thermo Elemental IRISIntrepid inductively coupled plasma atomic emission spectrometer(ICP-AES). N2 adsorption-desorption isotherms were obtainedat -196 ℃ using a Quantachrome Quadrasorb S1 apparatus. Thepore volume was calculated from the amount of N2 adsorbed at arelative pressure of 0.99. The pore size distribution was calculatedwith the Barrett-Joyner-Halenda (BJH) model from the desorptionbranch. The powder X-ray diffraction (XRD) patterns wererecorded on a Bruker D8 Advance X-ray diffractometer usingCu-Ka radiation with a voltage of 40 kV and a current of 40 mA. Thetransmission electron microscope (TEM) images of Cu/Al2O3 and Co/Al2O3 catalysts were obtained from a FEI Tecnai G2 F20 S-TWINmicroscope, while those of Ni/Al2O3 catalyst were derived from aJEOL JEM2011 microscope. H2 temperature programmed reduction(H2-TPR) profiles of the calcined catalysts were recorded using aMicromeritics Chemisorb 2720 apparatus. 50 mg of sample wasplaced in a quartz reactor and heated at 10 ℃ min-1 up to 200 ℃under a He flow of 50 mL min-1, and held at this temperature for2 h. The reactor was then cooled down to 100 ℃. H2-TPR wasperformed using a 10% H2/Ar mixture at a flow rate of 50 mL min-1while the temperature was linearly ramped from 100 ℃ to 950 ℃at 3 ℃ min-1. The dispersion of Ni/Al2O3 and Co/Al2O3 wasanalyzed by the temperature programmed desorption of carbonmonoxide (CO-TPD) with the assumption of CO:Ni or CO:Co(surface) stoichiometry of 1:1. The dispersion of Cu/Al2O3 catalystwas determined by the dissociative N2O adsorption method [18].

2.3. Catalytic reaction

Catalytic activity test was carried out in a fixed-bed reactor. Ineach run, 0.25 g of catalyst (60-80 mesh) was placed at the centerof the reactor tube between two layers of silica sands. The reactiontemperature was continuously monitored using a thermocoupletouching the catalyst bed firmly. Prior to the reaction, the catalystwas pre-reduced under a flow of 5% H2/Ar (50 mL min-1) for 2 h at450 ℃ for Cu/Al2O3 and Co/Al2O3 and 750 ℃ for Ni/Al2O3. Afterreduction, the catalyst was cooled down to a desired reactiontemperature (120-200 ℃) and a mixture consisting of MA and GBLwith a weight ratio of 15:85 were fed continuously into the reactorwith a H2/MA molar ratio of 24. The products were collected atintervals of 1 h and analyzed by gas chromatography (GC) with aflame ionization detector and a HP-5 capillary column. Based onthe GC results the conversion of MA and the selectivity to theproduct i were calculated according to

$Conversion(MA)=\left( M{{A}_{in}}-M{{A}_{out}} \right)/M{{A}_{in}}\times 100%$ (1)
$\text{Selectivity}\left( i \right)=\text{Produc}{{\text{t}}_{i,out}}/\left( M{{A}_{in}}-M{{A}_{out}} \right)\times 100%$ (2)

where, MAin, MAout and Producti, out represent the molar concentrationof inlet reactant, outlet reactant and outlet products, respectively.

3. Results and discussion 3.1. Characterization

The chemical compositions and textural properties of the Cu/Al2O3, Co/Al2O3 and Ni/Al2O3 catalysts before H2 reduction andAl2O3 support are summarized in Table 1. As seen in Table 1, thesurface area for the Al2O3 support is 214 m2 g-1 and pore volume is1.14 cm3 g-1. Three catalysts, Cu/Al2O3, Co/Al2O3 and Ni/Al2O3, show slightly smaller surface area and pore volume after theimpregnation of metal species. The N2 adsorption-desorptionresults for the support and catalysts are shown in Fig. 1. Allisotherms are of type IV, which indicates that the samples maintainthe mesoporous structure after metal impregnation and calcinationtreatment. Metal dispersion is also a crucial factor indetermining catalytic performance [9, 19]. Based on the TEMimages of reduced Cu/Al2O3, Co/Al2O3 and Ni/Al2O3 catalysts (Fig.S3 in Supporting information), the nanoparticle size of Co species ismuch bigger than those for Cu and Ni species, suggesting therelatively poor Co dispersion. Moreover, the calculated dispersiondegree of Cu, Co and Ni species after H2 reduction is 24.8%, 8.2% and14.4%, respectively, which is consistent with the TEM results.

Table 1
The physicochemical properties and catalytic performance of Cu/Al2O3, Co/Al2O3 and Ni/Al2O3 catalysts.

Figure 1. N2 adsorption-desorption isotherms of the support and the catalysts beforeH2 reduction.

The XRD patterns for the support and catalysts before H2reduction are shown in Fig. 2A. For the Al2O3 support, thediffraction peaks at 2u of 37.48, 39.78, 45.88 and 67.38 may beassigned to (3 1 1), (2 2 2), (4 0 0) and (5 2 2) diffractions of g-Al2O3(PDF No. 04-0880), respectively [20-22]. In the case of the calcineδCo/Al2O3, in addition to the diffractions of Al2O3 the peaksappeared at 2u of 31.38, 36.88, 44.88, 59.48 and 65.28 are attributedto Co3O4 (PDF No. 43-1003) [23, 24]. The nickel and copper oxidephases were not observed, indicating the metal species are highlydispersed on the support, which are in agreement with the Ni/Al2O3 and Cu/Al2O3 catalysts dispersion results.

Figure 2. The XRD patterns of the catalysts before (A) and after (B) H2 reduction

Fig. 2B shows XRD results of the H2-reduced samples. No peakfor Cu and Ni species was detected, indicating that Cu and Nispecies are highly dispersed on the support after reduction. For thereduced Co/Al2O3 catalyst, one peak at 44.28 may be attributed to(1 1 1) diffraction of Co (PDF No. 15-0806).

H2-TPR results are shown in Fig. 3. The Cu/Al2O3 catalyst showsa single peak around 180 ℃ which is attributed to the reduction of CuO to metal Cu [25]. For the Co/Al2O3 catalyst, a two-stepreduction of cobalt oxide was observed. The peaks at 310 ℃ and340 ℃ are ascribed to the reduction of Co3O4 to CoO and CoO tometallic cobalt, respectively [26, 27]. The reducibility profile of Ni isdifferent from Cu and Co catalysts and displays a main reductionpeak at 550 ℃ with two shoulder peaks around 330 ℃ and 750 ℃.The reduction peak at low temperature (330 ℃) is assigned to thereduction of free Ni oxides species which have weak interactionwith the support, while the main peak at 550 ℃ is generallyattributed to the reduction of NiO retaining stronger interactionwith the support [28-30]. The peak at high temperature (750 ℃) isascribed to the reduction of the formed complex Ni-Al species suchas NiAl2O4 [28-30].

3.2. Catalytic activities

The activity over three catalysts with different metal for the MAhydrogenation at 140 ℃, 0.5 MPa of hydrogen and a WHSV of 2 h-1is illustrated in Fig. 4. Ni/Al2O3 catalyst shows the highest MAconversion along with the highest stability in the time course(Fig. 4A). The selectivity to SA and GBL over different catalysts isshown in Fig. 4B and C, respectively. No significant amountsof overhydrogenated compounds, such as THF and BDO, wereobserved. The products are SA and GBL, and SA is the main productat this temperature. Over Cu/Al2O3 and Co/Al2O3 catalysts the lowactivity and significant deactivation were observed, indicating pooractivities of Cu and Co catalysts for MA hydrogenation.

Figure 3. H2-TPR profiles of the Cu/Al2O3, Co/Al2O3 and Ni/Al2O3 catalysts.

To obtain further insight into the true activity rate of Cu, Co andNi, turnover frequencies (TOF) of Cu, Co and Ni catalysts are listedin Table 1. The TOF values also imply that Ni/Al2O3 is more activethan Cu/Al2O3 and Co/Al2O3. Numerous literature studies indicatethat, compared with Ni catalyst suitable for the reaction underlow-moderate temperature, Cu- and Co-based catalysts aregenerally required to operate at higher temperature (>200 ℃)due to their intrinsic poor ability of dissociating H2 [6, 7].

The effect of temperature on the MA conversion and theselectivities to SA and GBL over Ni/Al2O3 catalyst are shown inTable 2. The MA conversion increased from ∼95% to ∼100% withincreasing temperature from 120 ℃ to 140 ℃ (Table 2, entries1-2). This increment was also found in the selectivity to GBL. Butthe selectivity to SA decreased with increasing of temperature, which indicates that SA was further hydrogenated to give GBL.Based on the effects of reaction temperature on both MAconversion and SA selectivity, a highest SA yield of ∼92% couldbe obtained at 140 8C. It is apparent from the results that thedesired product selectivity can be obtained by controlling theoperating temperature. Guo et al. studied the effect of the reactiontemperature on the hydrogenation of MA to SA over Ni (7 wt%)/diatomite at temperature of 120-260 8C [31]. They found that theMA conversion roughly increased while the selectivity to SAdecreased with increasing the reaction temperature. In their work, ∼96% SA yield was obtained at 190 8C and 1 MPa of hydrogen. Theeffect of reaction temperature on the MA hydrogenation was alsoreported over Ni/TiO2 (molar ratio of Ni/Ti ∼ 0.15) catalyst and∼92% SA yield could be achieved at the optimized temperature of220 8C under 0.2 MPa of hydrogen [12]. In the present case, thehigh dispersion of Ni species and interaction between activespecies and the support may account for the high catalyticperformance of Ni/Al2O3 operated under low temperature.

Figure 4. (A) MA conversion, (B) SA selectivity and (C) GBL selectivity over Cu/Al2O3, Co/Al2O3 and Ni/Al2O3 catalysts with 7 h time on stream. Reaction conditions:temperature = 140 8C, pressure = 0.5 MPa and WHSV = 2 h-1 (MA).

Table 2
Effect of temperature on the Ni/Al2O3 catalyst

To evaluate the stability of Ni catalyst, Ni/Al2O3 was tested atoptimized temperature of 140 8C (Fig. 5). The MA conversion of∼100% and the SA selectivity of ∼92% were achieved at 140 8C and0.5 MPa of H2. Ni/Al2O3 catalyst exhibited excellent catalyticperformances, since no noticeable deactivation and distributionchange of the products were observed after ∼100 h on stream. XRDand TEM were also performed for the used catalyst. As shown inFig. S2 in Supporting information, the XRD shows that Al2O3diffraction peak (2u = 37.48 PDF No. 04-0880) intensity slightlydecreased and an additional diffraction peak at 2u of 27.08 may beassigned to g-AlOOH (PDF No. 48-0890), indicating that thesupport Al2O3 partially transformed into its hydrate g-AlOOHduring the reaction [32]. This phenomenon may be attributed toby-product of H2O in the MA hydrogenation [32]. Moreover, theXRD result of the used Ni/Al2O3 catalyst also shows that theparticle size of Ni remains unchanged and in line with the TEM (Fig.S3) results, reflecting the stability of the Ni/Al2O3 catalyst.

Figure 5. The catalytic stability test of Ni/Al2O3 at 140 8C with 0.5 MPa of reactionpressure and WHSV of 2 h-1.

4. Conclusion

In summary, we have developed a simple method to synthesizethe pseudo-boehmite derived alumina supported metal (Cu, Co and Ni) catalysts to catalyze the hydrogenation of MA to SA and GBL.The metal species were well dispersed on the mesoporous Al2O3and Ni/Al2O3 showed the excellent catalytic activity and goodstability in the MA hydrogenation at 140 8C and 0.5 MPa of H2. Theefficient pseudo-boehmite derived alumina supported Ni catalyst, therefore, has the potential industrial application for the hydrogenationof MA to SA and GBL under low temperature.


This work was supported by the National Natural ScienceFoundation of China (Nos. 21173050 and 21371035) and ChinaPetrochemical Corporation (No. X514005).

Appendix A. Supplementary data

Supplementary material related to this article can be found, in theonline version, at

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