20September2019

Nano-Micro Letters

Preparation of Palladium Supported on Ferric Oxide Nano-catalysts for Carbon Monoxide Oxidation in Low Temperature

Fagen Wang*, Yan Xu, Kunfeng Zhao, Dannong He*

Abstract
icon-htmlFull Text Html
icon-pdf-smPDF w/ Links
icon-citExport Citation
Figures
+Show more

Nano-Micro Letters, , Volume 6, Issue 3, pp 233-241

Publication Date (Web): July 1, 2014(Article)

DOI: 10.5101/nml140025a

*Corresponding author. E-mail: fagen.wang@gmail.com, hdnbill@sh163.net

 

Abstract

 


Figure discription XRD patterns of the as-prepared Pd/Fe2O3 catalysts.
Catalytic property of Pd/Fe2O3 catalysts on carbon monoxide (CO) oxidation at low temperature were investigated in this paper. Both the as-prepared and H2-pretreated Pd/Fe2O3 catalysts show catalytic performances on CO oxidation. The CO was completely converted at 333 K for the as-prepared sample, whereas at 313 K for H2-pretreated Pd/Fe2O3-573 catalyst. The catalytic performance of the Pd/Fe2O3 catalyst decreases with increased calcination temperature. This may be due to the increased crystallinity of the support and decreased metal-support interaction. Progressive deactivation of the catalysts during long-time reaction was associated with the formation of carbonates on the catalyst surface that inhibits CO activation or intermediate transformation.

 

Keywords

Pd/Fe2O3; Carbon monoxide; Catalytic oxidation; Low temperature

 

Full Text Html

 

1 Introduction

 

Carbon monoxide (CO) catalytic oxidation is considered as a very important reaction in environmental applications, for example, vehicle exhausts elimination in semi-closed spaces [1-3]. To date, this reaction was mostly studied on supported noble metal catalysts like Au, Pt and Pd due to their high activities at low temperatures [4-6]. However, high prices and deactivation drawbacks of these metal catalysts limit applications in many fields [5,7-9]. The deactivation was mainly originated from aggregation of active metal, coverage of carbonates and competitive adsorption between CO and moisture [10,11]. In contrast, much lower cost Pd catalyst showed comparable activity and long lifespan for CO oxidation at low temperatures [12-14]. It has a very potential possibility that Pd catalysts might replace Au catalysts for CO oxidation, especially when the catalysts needed to be prepared in large-scale and applied in engineering aspects.

 

Catalytic performance is found highly dependent on the catalyst preparation methods [15]. Co-precipitation is one of the simplest methods for preparation of homogeneous dispersed catalysts. Some results even showed single-atom dispersion that owning high intrinsic activity [16]. Pd nanoparticles can be synthesized by co-precipitation method with high dispersion, and exhibited excellent activity in CO oxidation [[17]. Because of the unique redox behavior and coordinative unsaturated Fe sites, Fe2O3 was considered to be an effective support for catalyst preparation [18,19]. It was reported that noble metals/FeOx are promising catalysts for CO oxidation [20].

 

In this paper, Pd/Fe2O3 catalysts were prepared by co-precipitation method and their application in CO oxidation at low temperatures was investigated. The advantages of H2-pretreated catalysts were analyzed, the reaction mechanism was discussed and the reason for deactivation was illustrated.

 

2 Experimental

 

PdCl2 (AR) was available from Heraeus Materials Technology Shanghai Ltd., Fe(NO3)3·9H2O (AR) and Na2CO3 (AR) from Sinopharm Chemical Reagent Co., Ltd. (SCRC).

 

The 2.0 wt% Pd/Fe2O3 catalysts were prepared by co-precipitation method. Typically, PdCl2 and Fe(NO3)3 were firstly dissolved in 60 mL de-ionic water and stirred for 30 min. Then, the mixture was slowly dropped into Na2CO3 aqueous solution at 338 K under vigorous stirring. The pH of the solution was maintained 8~9. After aged for 2 h, the brown precipitate was filtrated and washed by hot water for several times until the chloride ions were undetected by silver nitrate. The finally obtained slurry was dried at 373 K overnight and calcined for 4 h at 573, 673 and 773 K, respectively. The samples were noted as Pd/Fe2O3-T (T is the calcination temperature).

 

The Brunauer-Emmett-Teller (BET) specific surface area of the sample was measured by adsorption–desorption of nitrogen at 77 K using an ASAP 2020 instrument (Micromeritics). Before the measurement, the samples were degassed at 573 K for 3 h. The X-ray power diffraction (XRD) was carried out on a D/MAX-2600PC diffractometer (Rigaku) operated at 40 kV and 100 mA with Ni-filtered Cu Kα (0.15418 nm) radiation source. The patterns were collected from 10° to 70° (2θ) with a step width of 0.02°. Hydrogen temperature programmed reduction (H2-TPR) was performed with an Auto Chem II chemisorption analyzer (Micromeritics) using a thermal conductive detector (TCD). The sample was pretreated by He (30 mL/min) at 573 K for 1 h to remove surface contaminants. After cooling to 273 K, 10% H2/Ar (30 mL/min) mixture was introduced and the temperature was raised to 873 K at a rate of 10 K/min. The dispersion of Pd was measured by CO pulse chemisorption at 273 K. The transmission electron microscopy (TEM) images were obtained on a JEM-2100 (JEOL) instrument at an accelerating voltage of 200 kV.

 

The CO catalytic oxidation test was performed in a continuous-flow fixed-bed reactor (8 mm internal diameter) at atmospheric pressure. 0.5 g catalyst powder was loaded between two layers of quartz wool. Before the test, the as-prepared Pd/Fe2O3 catalysts were reduced by 10% H2/N2 (100 mL/min) at 353 K for 1 h. After the catalysts were cooled to 273 K under N2 (90 mL/min), the feed gas containing 100 ppm CO balanced with compressed air was passed through the reactor at 1000 mL/min. The reaction temperature, measured with a thermocouple, was increased from 273 K to 333 K at intervals of 10 K. CO concentration was monitored by an online CO analyzer Model 48i (Thermal Scientific).

 

The CO conversion was calculated according to the following equation,

X (%) = (COinlet- COoutlet)/COinlet x 100

where X is the CO conversion, COinlet is the initial CO concentration in the inlet, and COoutlet is the CO concentration in the outlet.

 

3 Results and discussion

 

3.1 Characterizations of the as-prepared catalysts

 

The ICP results of Pd content and BET surface areas of the as-prepared Pd/Fe2O3 catalysts are listed in Table 1. The Pd content was in the range of 1.82-1.89 wt%, closing to the theoretical value of 2.0 wt%. The BET specific surface area of the as-prepared Pd/Fe2O3-573 catalyst was 180 m2/g, whereas, it was decreased sharply to 79 and 35 m2/g for Pd/Fe2O3-673 and Pd/Fe2O3-773 catalyst, respectively. These results demonstrated that calcination at high temperature could dramatically decrease the BET specific surface of the as-prepared catalysts. This might be associated with that the number of support pores were decreased or the supports pores were blocked by the entry of some Pd species at higher temperatures [17].

 

Table 1 Caption The chemical and physical properties of the Pd/Fe2O3 catalysts.

Table 1 The chemical and physical properties of the Pd/Fe2O3 catalysts.

 

Figure 1 presents the XRD patterns of the as-prepared Pd/Fe2O3 catalysts. There is no observable PdO diffraction peak for all the catalysts, indicating that PdO is finely dispersed. The PdO nanoparticles size was maintained at about 2 nm in diameter (calculated according to the dispersion of Pd, Table 1) even after calcination at 773 K. While for the Fe2O3 support, the main diffraction peaks are all assigned to hexagonal Fe2O3 (PDF#33-0664). The support crystalline size was 9 nm for Pd/Fe2O3-573 catalyst, and it was increased to 22 nm for Pd/Fe2O3-673 and 31 nm for Pd/Fe2O3-773 catalysts with the calcination temperature increasing, which is in accordance with the BET specific surface results.

 

Figure 1 Caption XRD patterns of the as-prepared Pd/Fe2O3 catalysts.

Figure 1 XRD patterns of the as-prepared Pd/Fe2O3 catalysts.

 

The sintering of the Fe2O3 support is further confirmed by the TEM images shown in Fig. 2. The Pd/Fe2O3-573 catalyst had the average Fe2O3 crystalline size of ~10 nm (see Fig. 2A). When the calcination temperature was increased to 673 K (Pd/Fe2O3-673), the Fe2O3 size was increased to ~20 nm (see Fig. 2B), and further increased to ~30 nm at 773 K (Pd/Fe2O3-773) (see Fig. 2C). There is no visible PdO nanoparticle, because the 2 nm PdO particle is impossible to be distinguished from the speckle contrast exhibited by the support.

 

Figure 2 Caption TEM images of the as-prepared Pd/Fe2O3 catalysts: (A) 573 K; (B) 673 K; and (C) 773 K.

Figure 2 TEM images of the as-prepared Pd/Fe2O3 catalysts: (A) 573 K; (B) 673 K; and (C) 773 K.

 

H2-TPR experiments were carried out on the as-prepared Pd/Fe2O3 catalysts, and the profiles are displayed in Figure 3. The temperatures of reduction peaks maxima and the quantitative evaluation of H2 consumption are given in Table 2. The reduction peaks of PdO species were centered at 316~340 K [14,21]. Among these three catalysts, Pd/Fe2O3-573 exhibited the largest H2 consumption below 400 K (shown in Table 2), which might be associated with the strongest metal-support interaction [22]. In the case of Pd/Fe2O3-573 catalyst, the H2 consumption at 340 K was 355 µmol/gcat, which was much larger than 155 µmol/gcat of theoretical value for PdO to Pd, indicating the co-reduction of PdO and partial surface Fe2O3 near the Pd nanoparticles where hydrogen can easily spillover onto the support surface [23]. The reduction peak centered at 450 K (H2 consumption is 352 µmol/gcat) was due to the further reduction of Fe2O3 to Fe3O4. It appears that Pd could enhance the Fe2O3 support reducibility significantly since the reduction temperature was much lower than the typical one of 633 K for Fe2O3 to Fe3O4 [24,25]. The reduction behaviors of Pd/Fe2O3-673 and Pd/Fe2O3-773 catalysts were similar to that of the Pd/Fe2O3-573 catalyst. However, the Pd enhancement becomes weaker by considering that the H2 consumption at low temperature (~320 K) was decreased and the reduction temperature for Fe2O3 to Fe3O4 was shifted to higher temperatures.

 

Figure 3 Caption H2-TPR profiles of the as-prepared Pd/Fe2O3 catalysts.

Figure 3 H2-TPR profiles of the as-prepared Pd/Fe2O3 catalysts.

 

Table 2 Caption H2-TPR analysis of the Pd/Fe2O3 catalysts.

Table 2 H2-TPR analysis of the Pd/Fe2O3 catalysts.

 

 

3.2 Catalytic performance of the Pd/Fe2O3 catalysts in CO oxidation

 

3.2.1 Catalytic activity of the Pd/Fe2O3 catalysts

 

Figure 4 shows the catalytic activity in CO oxidation of the as-prepared and H2-pretreated Pd/Fe2O3 catalysts. For the as-prepared catalysts, (see Fig. 4A) the T50 (The temperature corresponding to 50% CO conversion) was 287 K for Pd/Fe2O3-573, 309 K for Pd/Fe2O3-673, and 313 K for Pd/Fe2O3-773 catalysts, respectively. A 100% CO conversion was observed on the Pd/Fe2O3-573 catalyst at 333 K, whereas, they were corresponded to only 80% and 70% for the Pd/Fe2O3-673 and Pd/Fe2O3-773 catalysts at the same temperature. The results indicated that CO could be oxidized by PdO species without pre-reduction [25]. This might be due to the redox behavior of the highly dispersed PdO nanoparticles: PdO + COà Pd + CO2, 2Pd + O2à 2PdO.

 

The H2 pretreatment promoted the catalytic activity of the Pd/Fe2O3 catalysts, and the results are shown in Fig. 4B. The CO conversion at 273 K was 50~55% for the Pd/Fe2O3-773 and Pd/Fe2O3-673 catalysts, which was slightly lower than 65% for the Pd/Fe2O3-573 catalyst. For all the three catalysts, the CO conversion was about 70% at 283 K, and increased to 100% at 323 K. The much higher performances of the H2-pretreated Pd/Fe2O3 catalysts may be due to the well dispersed Pd nanoparticles and the unique Pd-Fe2O3 interaction [26]. It was considered that the well dispersed Pd nanoparticles would weaken C-O and O-O bonds after CO and O2 adsorption, influencing the interaction between the surface and the adsorbents and favoring CO activation [20,27].

 

Figure 4 Caption Catalytic activity in CO oxidation of the Pd/Fe2O3 catalysts (Reaction conditions: mass of catalyst: 0.5 g; Total flow rate: 1000 mL/min; Feedstock: 100 ppm CO/air; GHSV=120,000 mL/gh).

Figure 4 Catalytic activity in CO oxidation of the Pd/Fe2O3 catalysts (Reaction conditions: mass of catalyst: 0.5 g; Total flow rate: 1000 mL/min; Feedstock: 100 ppm CO/air; GHSV=120,000 mL/gh).

 

3.2.2 The influence of Pd loading content

 

The influence of amounts of Pd loading on CO oxidation conversion for the as-prepared and H2-pretreated Pd/Fe2O3 catalysts is shown in Fig. 5. It is clearly seen that the CO conversion was all improved when the loaded Pd content was increased. For the as-prepared Pd/Fe2O3-573 catalyst, the CO conversion was increased from 68% to 90% when Pd content was increased from 1 wt% to 3 wt%. Similarly, it was increased from 79% to 99% for H2-pretreated Pd/Fe2O3-573 catalyst. This may be explained by the more active sites which were produced as the loaded Pd content increased for CO adsorption, activation and intermediates transformation.

 

Figure 5 Caption The influences of Pd loading content on CO conversion over the (A) as-prepared and (B) H2-pretreated Pd/Fe2O3 catalysts calcined at 573 K (Reaction conditions: mass of catalyst: 1.0 g; Total flow rate: 1000mL/min; Feedstock: 100 ppm CO/air; T: 303 K, GHSV=60,000 mL/gh).

Figure 5 The influences of Pd loading content on CO conversion over the (A) as-prepared and (B) H2-pretreated Pd/Fe2O3 catalysts calcined at 573 K (Reaction conditions: mass of catalyst: 1.0 g; Total flow rate: 1000mL/min; Feedstock: 100 ppm CO/air; T: 303 K, GHSV=60,000 mL/gh).

 

3.2.3 The influence of gas hourly space velocity (GHSV)

 

The catalytic performances of the as-prepared and H2-pretreated Pd/Fe2O3-573 catalysts under different gas hourly space velocity (GHSV) were performed at 303 K (Fig. 6). For all the catalysts, a higher space velocity resulted in a lower CO conversion. This was accounted on the decreased reactants residence time on the catalyst surface with the increased GHSV. However, the decrease extents were different. The CO conversion was decreased from 81% to 72% when the space velocity was increased from 60,000 mL/(gh) to 120,000 mL/(gh) over the as-prepared Pd/Fe2O3-573 catalyst. While for the H2-pretreated catalysts, the CO conversion was only slightly decreased from 99% to 97% with the gas hourly space velocity was increased from 60,000 mL/(gh) to 120,000 mL/(gh). The results suggested that the CO oxidation reaction rate was much faster on the H2-pretreated catalyst than that on the as-prepared catalyst.

 

Figure 6 Caption The Influences of gas hourly space velocity on CO conversion over the as-prepared and H2-pretreated Pd/Fe2O3 catalysts calcined at 573 K (Reaction conditions: mass of catalyst: 0.5~1.0 g; Total flow rate: 1000 mL/min; Feedstock: 100 ppm CO/air; T: 303 K).

Figure 6 The Influences of gas hourly space velocity on CO conversion over the as-prepared and H2-pretreated Pd/Fe2O3 catalysts calcined at 573 K (Reaction conditions: mass of catalyst: 0.5~1.0 g; Total flow rate: 1000 mL/min; Feedstock: 100 ppm CO/air; T: 303 K).

 

3.2.4 The intrinsic rate of CO conversion

 

The excellent activity of the Pd/Fe2O3 catalysts can be further confirmed from Table 3, where a comparison of the specific rate of the as-prepared and H2-pretreated Pd/Fe2O3 catalysts for CO oxidation with a range of supported Pd and Au catalysts from the literatures has been made. The as-prepared Pd/Fe2O3 catalyst showed a relative high specific rate (4.3 ´ 10-2 mol/gPdh), which was as active as Au/La2O3 catalyst (specific rate is 4.0 ´ 10-2 mol/gAuh). The H2 pretreatment enhanced the activity further, the specific rate over the H2-pretreated Pd/Fe2O3 catalyst was increased to 10.7 ´ 10-2 mol/gPdh, which was a little higher than that of the Au/Fe2O3 catalyst (9.1 ´ 10-2 mol/gAuh) prepared by deposition-precipitation method [17,28]. These results showed that the activities of Fe2O3-supported Pd catalysts may be comparable to those of supported Au catalysts for CO oxidation.

 

In order to have an insight into the intrinsic activities of the Pd catalysts, the turn over frequencies (TOFs) were also compared in Table 3. As expected, the TOF of H2-pretreated Pd/Fe2O3-573 catalyst was 0.038 s-1, exhibiting significantly higher activity than that of the as-prepared Pd/Fe2O3-573 catalyst (TOF = 0.012 s-1). The TOF of the H2-pretreat Pd/Fe2O3-573 catalyst was comparable to that of the Au/CeO2 catalyst (TOF = 0.047s-1) [29] and the commercial Au/Fe2O3 catalyst (TOF = 0.04 s-1) [14]. Taken reaction temperature into account, the H2-pretreat Pd/Fe2O3-573 catalyst is much active than the Pd/SiO2 catalyst (298 K vs. 450 K, TOF=3.1s-1) [30]. The TOF value of H2-pretreat Pd/Fe2O3-573 catalyst was in great agreement with the same Pd/Fe2O3 catalyst reported in reference [17]. This was assigned to the small size of the synthesized Pd nanoparticles ([31]. It was well known that the size of metal particles plays an important role in CO activation. The TOF results strongly suggested that supported Pd catalysts may be a good alternative to gold in CO oxidation if proper preparation method and support are adopted.

 

Table 3 Caption Specific rates of CO conversion and TOFs data of catalysts from this work and literatures.

Table 3 Specific rates of CO conversion and TOFs data of catalysts from this work and literatures.

 

3.3 Stability of the Pd/Fe2O3 catalysts for CO oxidation

 

The stability of Pd/Fe2O3 catalysts shown in Fig. 7 was tested at 293 K. The CO conversion was readily decreased from 70% to 65% for the Pd/Fe2O3-573 catalyst after 10 h (Fig. 7A). For Pd/Fe2O3-673 catalyst it maintained around 40%, whereas, for Pd/Fe2O3-773 catalyst it decreased from 35% to 25% after 10 h. The stability test further evidenced the highest performance of the as-prepared Pd/Fe2O3-573 catalyst. Because the reaction temperature (293 K) was much lower than the calcination (573 K) and reduction temperature (353 K), it was inferred that no obvious PdO or Fe2O3 sintering was occurred during the reaction course. Hence the deactivation of the as-prepared Pd/Fe2O3 catalysts might be originated from the gradually deposition of soft carbonate or carbonyl species on the catalyst surface.

 

Figure 7B shows the stability of CO conversion over the H2-pretreated Pd/Fe2O3 catalysts. The initial CO conversion was about 90%, and the CO conversion was decreased with the time on stream increasing over the three catalysts. After 10 h, CO conversion was decreased to 80%, 70% and 40% over the Pd/Fe2O3-573, Pd/Fe2O3-673 and Pd/Fe2O3-773 catalysts, respectively. The results demonstrated that Pd/Fe2O3-573 catalyst is the most efficient for CO oxidation. It might be associated with the smallest size of Pd (1.8 nm) and the strongest metal-support interaction (Fig. 3) over the Pd/Fe2O3-573 catalyst. Although the Pd sizes over the Pd/Fe2O3-673 and Pd/Fe2O3-773 catalysts were close (2.0 nm and 2.1 nm, respectively), the metal-support interaction was not as strong as that over the Pd/Fe2O3-573 catalyst. Similar to the as-prepared catalysts, the deactivation of the H2-pretreated catalysts could also be contributed to the gradually deposition of carbonates on the surface of catalyst, which hindered the activation of CO and blocked the transformation of intermediates, as discussed later.

 

Figure 7 Caption CO conversion of the Pd/Fe2O3 catalysts as a function of time at 293K (Reaction conditions: mass of catalyst: 0.5 g; Total flow rate: 1000 mL/min; Feedstock: 100 ppm CO/air; T: 293 K; GHSV=120,000 mL/gh).

Figure 7 CO conversion of the Pd/Fe2O3 catalysts as a function of time at 293K (Reaction conditions: mass of catalyst: 0.5 g; Total flow rate: 1000 mL/min; Feedstock: 100 ppm CO/air; T: 293 K; GHSV=120,000 mL/gh).

 

3.4 Characterizations of the used catalysts

 

3.4.1 XRD patterns

 

In order to clarify the causes of deactivation of the catalysts, characterizations of the used catalysts were carried on. Figure 8 gives the XRD patterns of the used as-prepared and H2-pretreated Pd/Fe2O3 catalysts. The XRD patterns of the used as-prepared Pd/Fe2O3 catalysts (Fig. 8A) showed the exact same profiles with the fresh ones. The Fe2O3 diffraction peaks were present and their crystalline sizes kept constant. The diffraction peak of PdO species was still not detected. These observations confirmed that the sintering of PdO and Fe2O3 species were not occurred. In contrast, obvious differences were observed over the used H2-pretreated Pd/Fe2O3 catalysts (Fig. 8B). The diffraction peaks of Fe2O3 species were much weaker and the diffraction peaks of Fe3O4 species were appeared. This indicated that the hydrogen pretreatment reduced most of the Fe2O3 to Fe3O4. Pd species were not detected in these used samples, indicating that they were highly dispersed or below the limitation of XRD apparatus. Hence Pd/Fe3O4 catalysts were formed after the hydrogen pretreatment. It has been reported that Fe3O4 contained surface hydroxyl group and was helpful for oxygen activation [17]. So the catalytic performance of the H2-pretreated catalysts was much higher than that of the as-prepared catalysts.

 

Figure 8 Caption XRD patterns of used (A) as-prepared and (B) H2-pretreated Pd/Fe2O3 catalysts after the stability test.

Figure 8 XRD patterns of used (A) as-prepared and (B) H2-pretreated Pd/Fe2O3 catalysts after the stability test.

 

3.4.2 FTIR analysis of the H2-pretreated Pd/Fe2O3 catalysts

 

Figure 9 presents the FTIR analysis of the H2-pretreated Pd/Fe2O3 catalysts to identify the carboxyl species on the catalyst surface. In the carbonate-like species range (1000-1700 cm-1) [32], the peak at 1415 cm-1 was related to the unidentate carbonate species [33], and 1539 cm-1 was detected for the carboxylate species [13]. The band observed at 1630 cm-1 was assigned to the bidentate carbonates [9,34]. In the carbonyl region (1800-2250 cm-1), CO adsorption and activation was observed. 1977 cm-1 was due to CO bridged adsorption on Pd0 and 2162 cm-1 was related to the CO interacting with partially oxidized Pd center [13]. The IR spectroscopy clearly demonstrated that the carbonate species were formed after the stability tests and gave an insight on the activation of CO. It was suggested that CO was adsorbed on the Pd0 and activated on the partially oxidized Pd (because of the presence of oxygen in the feed). The intermediates (carbonates or carbonyl species) were transformed to CO2 in the Pd-Fe2O3 interface. However, due to the much less adsorption and activation of CO, the catalytic performance of the as-prepared catalysts was not as good as that of the H2-pretreated catalysts. In addition, the carbonates on the surface would further cover the surface of the active sites and block the mobility and transformation of the intermediates, resulting in the deactivation with the time on stream [35].

 

Figure 9 Caption IR analysis of the used H2-pretreated Pd/Fe2O3 catalysts after the stability test.

Figure 9 IR analysis of the used H2-pretreated Pd/Fe2O3 catalysts after the stability test.

 

4 Conclusions

 

Pd/Fe2O3 nano-catalysts were synthesized by co-precipitation method and were investigated for CO oxidation in this study. The results revealed that both the as-prepared and H2-pretreated catalysts showed high performance for CO catalytic oxidation at low temperatures. T50 was 293 K and 273 K over the as-prepared and the H2-pretreated catalysts, respectively. CO can fully be converted at temperature as low as 313 K over the H2-pretreated catalysts. During the long time stability test, CO conversion was above 80% over the H2-pretreated Pd/Fe2O3-573 catalyst, while 60% conversion was maintained over the as-prepared Pd/Fe2O3-573 catalyst. The higher calcination temperature deduced a lower performance, which was associated with the different crystalline size and metal-support interaction of the catalyst. The much higher performance of the H2-pretreated catalysts was attributed to the Fe3O4 formation and surface OH group. The former was helpful to the O activation, and the latter was reacted with CO to form reactive adsorbed intermediates. The deactivation caused of the catalyst was assigned to the carbonates formation on the surface that hindered the CO activation and intermediates transformation.

 

Acknowledgments

 

This work was financially supported by National Key Research Program of China (Grant number 2013CB933200)

 

References

 

[1] K. N. Rao, P. Bharali, G. Thrimurthulu and B. M. Reddy, "Supported Copper–ceria catalysts for low temperature CO oxidation", Catal. Commun. 11(10), 863-866 (2010). http://dx.doi.org/10.1016/j.catcom.2010.03.009

[2] D. Gamarra, C. Belver, M. Garcia, and A. Arias, "Selective CO oxidation in excess H2 over copper−ceria catalysts: identification of active entities/species", J. Am. Chem. Soc. 129(40), 12064-12065 (2007). http://dx.doi.org/10.1021/ja073926g

[3] W. Xie, Y. Li, Z. Liu, M. Haruta and W. Shen, "Low-temperature oxidation of CO catalysed by Co3O4 nanorods", Nature 458(7239), 746-749 (2009). http://dx.doi.org/10.1038/nature07877

[4] K. Zhao, B. Qiao, J. Wang, Y. Zhang and T. Zhang, "A highly active and sintering-resistant Au/FeOx-hydroxyapatite catalyst for CO oxidation", Chem. Commun., 47(6), 1779-1781 (2011).http://dx.doi.org/10.1039/C0CC04171H

[5] S. Li, G. Liu, H. Lian, M. Jia, G. Zhao, D. Jiang and W. Zhang, "Low-temperature CO oxidation over supported Pt catalysts prepared by colloid-deposition method", Catal. Commun. 9(6), 1045-1049 (2008). http://dx.doi.org/10.1016/j.catcom.2007.10.016

[6] A. Satsuma, K. Osaki, M. Yanagihara, J. Ohyama and K. Shimizu, "Activity controlling factors for low-temperature oxidation of CO over supported Pd catalysts", Appl. Catal. B: Environ. 132-133, 511-518 (2013). http://dx.doi.org/10.1016/j.apcatb.2012.12.025

[7] M. Haruta, "Gold as a novel catalyst in the 21st century: Preparation, working mechanism and applications", Gold Bull. 37(1-2), 27-36 (2004). http://dx.doi.org/10.1007/BF03215514

[8] J. Moghaddam, S. Mollaesmail and S. Karimi, "The Influence of Morphology on Photo-catalytic Activity and Optical Properties of Nano-crystalline ZnO Powder", Nano-Micro Letters. 4(4), 197-201 (2012). http://dx.doi.org/10.3786/nml.v4i4.p197-201

[9]M. A. Bollinger and M. A. Vannice, "A kinetic and DRIFT study of low temperature carbon monoxide over Au-TiO2 catalysts", Appl. Catal. B: Environ. 8(4), 417-443 (1996). http://dx.doi.org/10.1016/0926-3373(96)90129-0

[10]G. Y. Wang, H. L. Lian, W. X. Zhang, D. Z. Jiang and T. H. Wu, "Stability and deactivation of Au/Fe2O3 catalysts for CO oxidation at ambient temperature and moisture", Kin. Catal. 43(3), 433-442 (2002). http://dx.doi.org/10.1023/A:1016026405985

[11]M. Dateand M. Haruta, "Moisture effect on CO oxidation over Au/TiO2 catalyst", J. Catal. 201(2), 221-224 (2001). http://dx.doi.org/10.1006/jcat.2001.3254

[12] M. Jin, J. Park, J. Shon, Z. Li, Y. Park and J. Kim, "Low temperature CO oxidation over Pd catalysts supported on highly ordered mesoporous metal oxides", Catal. Today 185(1), 183-190 (2012). http://dx.doi.org/10.1016/j.cattod.2011.09.019

[13] F. Liang, H. Zhu, Z. Qin, G. Wang and J. Wang, "Effects of CO2 on the stability of Pd/CeO2–TiO2 catalyst for low-temperature CO oxidation", Catal. Commun. 10(5), 737-740 (2009). http://dx.doi.org/10.1016/j.catcom.2008.11.031

[14] B. Qiao, L. Liu, J. Zhang and Y. Deng, "Preparation of highly effective ferric hydroxide supported noble metal catalysts for CO oxidations: From gold to palladium", J. Catal. 261(2), 241-244 (2009). http://dx.doi.org/10.1016/j.jcat.2008.11.012

[15] S. Bernal, J. J. Calvino, M. A. Cauqui, J. M. Gatica, C. Larese, J. A. P. Omil and J. M. Pintado, "Some recent results on metal/support interaction effects in NM/CeO2 (NM: noble metal) catalysts", Catal. Today 50(2), 175-206 (1999). http://dx.doi.org/10.1016/S0920-5861(98)00503-3

[16] B. Qiao, A. Wang, X. Yang, L. F. Allard, Z. Jiang, Y. Cui, J. Liu, J. Li and T. Zhang, "Single-atom catalysis of CO oxidation using Pt1/FeOx", Nature Chem. 3(8), 634-641 (2011). http://dx.doi.org/10.1038/nchem.1095

[17] L. Liu, F. Zhou, L. Wang, X. Qi, F. Shi and Y. Deng, "Low-temperature CO oxidation over supported Pt, Pd catalysts: Particular role of FeOx support for oxygen supply during reactions". J. Catal. 274(1), 1-10 (2010). http://dx.doi.org/10.1016/j.jcat.2010.05.022

[18] Q. Fu, W. Li, Y. Yao, H. Liu,H. Su, D. Ma, X. Gu, L. Chen, Z. Wang, H. Zhang, B. Wang and X. H. Bao, "Interface-confined ferrous centers for catalytic oxidation", Science 238(5982), 1141-1144 (2010). http://dx.doi.org/10.1126/science.1188267

[19] L. Li, A. Wang, B. Qiao, J. Lin, Y. Huang, X. Wang and T. Zhang, "Origin of the high activity of Au/FeOx for low-temperature CO oxidation: Direct evidence for a redox mechanism", J. Catal. 299, 90-100 (2013). http://dx.doi.org/10.1016/j.jcat.2012.11.019

[20] L. Liu, B. Qiao,Y. He, F. Zhou, B. Yang and Y. Deng, "Catalytic co-oxidation of CO and H2 over FeOx-supported Pd catalyst at low temperatures", J. Catal. 294, 29-36 (2012). http://dx.doi.org/10.1016/j.jcat.2012.06.018

[21] M. G. Musolino, C. Busacca, F. Mauriello and R. Pietropaolo, "Aliphatic carbonyl reduction promoted by palladium catalysts under mild conditions", Appl. Catal. A: Gen. 379(1-2), 77-86 (2010). http://dx.doi.org/10.1016/j.apcata.2010.03.008

[22] J. Jia, J. Shen, L. Lin, Z. Xu, T. Zhang and D. Liang, "A study on reduction behaviors of the supported platinum–iron catalysts", J. Mol. Catal. A: Chem. 138(2-3), 177-184 (1999). http://dx.doi.org/10.1016/S1381-1169(98)00147-2

[23] W. C. Conner and J. L. Falconer, "Spillover in Heterogeneous Catalysis", Chem. Rev. 95(3), 759-788 (1995). http://dx.doi.org/10.1021/cr00035a014

[24] X. Mou, B. Zhang, Y. Li, L. Yao, X. Wei, D. S. Su and W. Shen, "Rod-Shaped Fe2O3 as an Efficient Catalyst for the Selective Reduction of Nitrogen Oxide by Ammonia", Angew. Chem. Int. Ed. 51(12), 2989-2993 (2012). http://dx.doi.org/10.1002/anie.201107113

[25] S. H. Oh and G. B. Hoflund, "Low-temperature catalytic carbon monoxide oxidation over hydrous and anhydrous palladium oxide powders", J. Catal. 245(1), 35-44 (2007). http://dx.doi.org/10.1016/j.jcat.2006.09.016

[26] M. Jin, J. N. Park, J. K. Shon, J. H. Kim, Z. Li, Y. K. Park and J. M. Kim, "Low temperature CO oxidation over Pd catalysts supported on highly ordered mesoporous metal oxides", Catal. Today 185(1), 183-190 (2012). http://dx.doi.org/10.1016/j.cattod.2011.09.019

[27] S. Y. Christou and A. M. Efstathiou, "Effects of Pd Particle Size on the Rates of Oxygen Back-Spillover and CO Oxidation under Dynamic Oxygen Storage and Release Measurements over Pd/CeO2 Catalysts", Top Catal. 42-43(1-4), 351-355 (2007). http://dx.doi.org/10.1007/s11244-007-0204-0

[28]J. C. F. Gonzalez, V. A. Bhirud and B. C. Gates, "A highly active catalyst for CO oxidation at 298 K: mononuclear AuIII complexes anchored to La2O3 nanoparticles", Chem. Commun. 5275-5277 (2005). http://dx.doi.org/10.1039/b509629d

[29]T. Na, F. Wang, H. Li and W. Shen, "Influence of Au particle size on Au/CeO2 catalysts for CO oxidation", Catal. Today 175(1), 541-545 (2011). http://dx.doi.org/10.1016/j.cattod.2011.04.027

[30]N. W. Cant, P. C. Hicks and B. S. Lennon, "Steady-state oxidation of carbon monoxide over supported noble metals with particular reference to platinum", J. Catal. 54(3), 372-383 (1978). http://dx.doi.org/10.1016/0021-9517(78)90085-4

[31] I. Stara, V. Nehasil and V. Matolin, "The influence of particle size on CO oxidation on Pd/alumina model catalyst", Surf. Sci. 331–333, 173-177 (1995). http://dx.doi.org/10.1016/0039-6028(95)00183-2

[32] F. Boccuzzi, A. Chiorino, S. Tsubota and M. Haruta, "FTIR study of carbon monoxide and scrambling at room temperature over gold supported on ZnO and TiO2", J. Phys. Chem. 100(9), 3625-3631 (1996). http://dx.doi.org/10.1021/jp952259n

[33]T. Shido and Y. Iwasawa, "Reactant-promoted reaction mechanism for water-gas shift reaction on Rh-doped CeO2", J. Catal. 141(1), 71-81 (1993). http://dx.doi.org/10.1006/jcat.1993.1119

[34] B. Chang, B. W. Jang, S. Dai and S. H. Overbury, "Transient studies of the mechanism of CO oxidation over Au/TiO2 using time-resolved FTIR spectroscopy and product analysis", J. Catal. 236(2), 392-400 (2005). http://dx.doi.org/10.1016/j.jcat.2005.10.006

[35] Y. Shen, Y. Guo, L. Wang, Y. Wang, Y. Guo, X. Gong and G. Lu, "The stability and deactivation of Pd-Cu-Clx/Al2O3 catalyst for low temperature CO oxidation: an effect of moisture", Catal. Sci. Techno. 1, 1202-1207 (2011). http://dx.doi.org/10.1039/c1cy00146a

Acknowledgements

This work was financially supported by National Key Research Program of China (Grant number 2013CB933200) .

References

[1] K. N. Rao, P. Bharali, G. Thrimurthulu and B. M. Reddy, "Supported Copper–ceria catalysts for low temperature CO oxidation", Catal. Commun. 11(10), 863-866 (2010). http://dx.doi.org/10.1016/j.catcom.2010.03.009

[2] D. Gamarra, C. Belver, M. Garcia, and A. Arias, "Selective CO oxidation in excess H2 over copper−ceria catalysts: identification of active entities/species", J. Am. Chem. Soc. 129(40), 12064-12065 (2007). http://dx.doi.org/10.1021/ja073926g

[3] W. Xie, Y. Li, Z. Liu, M. Haruta and W. Shen, "Low-temperature oxidation of CO catalysed by Co3O4 nanorods", Nature 458(7239), 746-749 (2009). http://dx.doi.org/10.1038/nature07877

[4] K. Zhao, B. Qiao, J. Wang, Y. Zhang and T. Zhang, "A highly active and sintering-resistant Au/FeOx-hydroxyapatite catalyst for CO oxidation", Chem. Commun., 47(6), 1779-1781 (2011).http://dx.doi.org/10.1039/C0CC04171H

[5] S. Li, G. Liu, H. Lian, M. Jia, G. Zhao, D. Jiang and W. Zhang, "Low-temperature CO oxidation over supported Pt catalysts prepared by colloid-deposition method", Catal. Commun. 9(6), 1045-1049 (2008). http://dx.doi.org/10.1016/j.catcom.2007.10.016

[6] A. Satsuma, K. Osaki, M. Yanagihara, J. Ohyama and K. Shimizu, "Activity controlling factors for low-temperature oxidation of CO over supported Pd catalysts", Appl. Catal. B: Environ. 132-133, 511-518 (2013). http://dx.doi.org/10.1016/j.apcatb.2012.12.025

[7] M. Haruta, "Gold as a novel catalyst in the 21st century: Preparation, working mechanism and applications", Gold Bull. 37(1-2), 27-36 (2004). http://dx.doi.org/10.1007/BF03215514

[8] J. Moghaddam, S. Mollaesmail and S. Karimi, "The Influence of Morphology on Photo-catalytic Activity and Optical Properties of Nano-crystalline ZnO Powder", Nano-Micro Letters. 4(4), 197-201 (2012). http://dx.doi.org/10.3786/nml.v4i4.p197-201

[9]M. A. Bollinger and M. A. Vannice, "A kinetic and DRIFT study of low temperature carbon monoxide over Au-TiO2 catalysts", Appl. Catal. B: Environ. 8(4), 417-443 (1996). http://dx.doi.org/10.1016/0926-3373(96)90129-0

[10]G. Y. Wang, H. L. Lian, W. X. Zhang, D. Z. Jiang and T. H. Wu, "Stability and deactivation of Au/Fe2O3 catalysts for CO oxidation at ambient temperature and moisture", Kin. Catal. 43(3), 433-442 (2002). http://dx.doi.org/10.1023/A:1016026405985

[11]M. Dateand M. Haruta, "Moisture effect on CO oxidation over Au/TiO2 catalyst", J. Catal. 201(2), 221-224 (2001). http://dx.doi.org/10.1006/jcat.2001.3254

[12] M. Jin, J. Park, J. Shon, Z. Li, Y. Park and J. Kim, "Low temperature CO oxidation over Pd catalysts supported on highly ordered mesoporous metal oxides", Catal. Today 185(1), 183-190 (2012). http://dx.doi.org/10.1016/j.cattod.2011.09.019

[13] F. Liang, H. Zhu, Z. Qin, G. Wang and J. Wang, "Effects of CO2 on the stability of Pd/CeO2–TiO2 catalyst for low-temperature CO oxidation", Catal. Commun. 10(5), 737-740 (2009). http://dx.doi.org/10.1016/j.catcom.2008.11.031

[14] B. Qiao, L. Liu, J. Zhang and Y. Deng, "Preparation of highly effective ferric hydroxide supported noble metal catalysts for CO oxidations: From gold to palladium", J. Catal. 261(2), 241-244 (2009). http://dx.doi.org/10.1016/j.jcat.2008.11.012

[15] S. Bernal, J. J. Calvino, M. A. Cauqui, J. M. Gatica, C. Larese, J. A. P. Omil and J. M. Pintado, "Some recent results on metal/support interaction effects in NM/CeO2 (NM: noble metal) catalysts", Catal. Today 50(2), 175-206 (1999). http://dx.doi.org/10.1016/S0920-5861(98)00503-3

[16] B. Qiao, A. Wang, X. Yang, L. F. Allard, Z. Jiang, Y. Cui, J. Liu, J. Li and T. Zhang, "Single-atom catalysis of CO oxidation using Pt1/FeOx", Nature Chem. 3(8), 634-641 (2011). http://dx.doi.org/10.1038/nchem.1095

[17] L. Liu, F. Zhou, L. Wang, X. Qi, F. Shi and Y. Deng, "Low-temperature CO oxidation over supported Pt, Pd catalysts: Particular role of FeOx support for oxygen supply during reactions". J. Catal. 274(1), 1-10 (2010). http://dx.doi.org/10.1016/j.jcat.2010.05.022

[18] Q. Fu, W. Li, Y. Yao, H. Liu,H. Su, D. Ma, X. Gu, L. Chen, Z. Wang, H. Zhang, B. Wang and X. H. Bao, "Interface-confined ferrous centers for catalytic oxidation", Science 238(5982), 1141-1144 (2010). http://dx.doi.org/10.1126/science.1188267

[19] L. Li, A. Wang, B. Qiao, J. Lin, Y. Huang, X. Wang and T. Zhang, "Origin of the high activity of Au/FeOx for low-temperature CO oxidation: Direct evidence for a redox mechanism", J. Catal. 299, 90-100 (2013). http://dx.doi.org/10.1016/j.jcat.2012.11.019

[20] L. Liu, B. Qiao,Y. He, F. Zhou, B. Yang and Y. Deng, "Catalytic co-oxidation of CO and H2 over FeOx-supported Pd catalyst at low temperatures", J. Catal. 294, 29-36 (2012). http://dx.doi.org/10.1016/j.jcat.2012.06.018

[21] M. G. Musolino, C. Busacca, F. Mauriello and R. Pietropaolo, "Aliphatic carbonyl reduction promoted by palladium catalysts under mild conditions", Appl. Catal. A: Gen. 379(1-2), 77-86 (2010). http://dx.doi.org/10.1016/j.apcata.2010.03.008

[22] J. Jia, J. Shen, L. Lin, Z. Xu, T. Zhang and D. Liang, "A study on reduction behaviors of the supported platinum–iron catalysts", J. Mol. Catal. A: Chem. 138(2-3), 177-184 (1999). http://dx.doi.org/10.1016/S1381-1169(98)00147-2

[23] W. C. Conner and J. L. Falconer, "Spillover in Heterogeneous Catalysis", Chem. Rev. 95(3), 759-788 (1995). http://dx.doi.org/10.1021/cr00035a014

[24] X. Mou, B. Zhang, Y. Li, L. Yao, X. Wei, D. S. Su and W. Shen, "Rod-Shaped Fe2O3 as an Efficient Catalyst for the Selective Reduction of Nitrogen Oxide by Ammonia", Angew. Chem. Int. Ed. 51(12), 2989-2993 (2012). http://dx.doi.org/10.1002/anie.201107113

[25] S. H. Oh and G. B. Hoflund, "Low-temperature catalytic carbon monoxide oxidation over hydrous and anhydrous palladium oxide powders", J. Catal. 245(1), 35-44 (2007). http://dx.doi.org/10.1016/j.jcat.2006.09.016

[26] M. Jin, J. N. Park, J. K. Shon, J. H. Kim, Z. Li, Y. K. Park and J. M. Kim, "Low temperature CO oxidation over Pd catalysts supported on highly ordered mesoporous metal oxides", Catal. Today 185(1), 183-190 (2012). http://dx.doi.org/10.1016/j.cattod.2011.09.019

[27] S. Y. Christou and A. M. Efstathiou, "Effects of Pd Particle Size on the Rates of Oxygen Back-Spillover and CO Oxidation under Dynamic Oxygen Storage and Release Measurements over Pd/CeO2 Catalysts", Top Catal. 42-43(1-4), 351-355 (2007). http://dx.doi.org/10.1007/s11244-007-0204-0

[28]J. C. F. Gonzalez, V. A. Bhirud and B. C. Gates, "A highly active catalyst for CO oxidation at 298 K: mononuclear AuIII complexes anchored to La2O3 nanoparticles", Chem. Commun. 5275-5277 (2005). http://dx.doi.org/10.1039/b509629d

[29]T. Na, F. Wang, H. Li and W. Shen, "Influence of Au particle size on Au/CeO2 catalysts for CO oxidation", Catal. Today 175(1), 541-545 (2011). http://dx.doi.org/10.1016/j.cattod.2011.04.027

[30]N. W. Cant, P. C. Hicks and B. S. Lennon, "Steady-state oxidation of carbon monoxide over supported noble metals with particular reference to platinum", J. Catal. 54(3), 372-383 (1978). http://dx.doi.org/10.1016/0021-9517(78)90085-4

[31] I. Stara, V. Nehasil and V. Matolin, "The influence of particle size on CO oxidation on Pd/alumina model catalyst", Surf. Sci. 331–333, 173-177 (1995). http://dx.doi.org/10.1016/0039-6028(95)00183-2

[32] F. Boccuzzi, A. Chiorino, S. Tsubota and M. Haruta, "FTIR study of carbon monoxide and scrambling at room temperature over gold supported on ZnO and TiO2", J. Phys. Chem. 100(9), 3625-3631 (1996). http://dx.doi.org/10.1021/jp952259n

[33]T. Shido and Y. Iwasawa, "Reactant-promoted reaction mechanism for water-gas shift reaction on Rh-doped CeO2", J. Catal. 141(1), 71-81 (1993). http://dx.doi.org/10.1006/jcat.1993.1119

[34] B. Chang, B. W. Jang, S. Dai and S. H. Overbury, "Transient studies of the mechanism of CO oxidation over Au/TiO2 using time-resolved FTIR spectroscopy and product analysis", J. Catal. 236(2), 392-400 (2005). http://dx.doi.org/10.1016/j.jcat.2005.10.006

[35] Y. Shen, Y. Guo, L. Wang, Y. Wang, Y. Guo, X. Gong and G. Lu, "The stability and deactivation of Pd-Cu-Clx/Al2O3 catalyst for low temperature CO oxidation: an effect of moisture", Catal. Sci. Techno. 1, 1202-1207 (2011). http://dx.doi.org/10.1039/c1cy00146a

Citation Information

Fagen Wang, Yan Xu, Kunfeng Zhao and Dannong He, Preparation of Palladium Supported on Ferric Oxide Nano-catalysts for Carbon Monoxide Oxidation in Low Temperature. Nano-Micro Lett. 6(3),233-241 (2014). http://dx.doi.org/10.5101/nml140025a

History

Received 05 November 2013; accepted 26 January 2014; published online July 1, 2014

 


Additional Info

  • Type of Publishing: JOUR - Journal
  • Title:

    Preparation of Palladium Supported on Ferric Oxide Nano-catalysts for Carbon Monoxide Oxidation in Low Temperature

  • Author: Fagen Wang, Yan Xu, Kunfeng Zhao, Dannong He
  • Year: 2014
  • Volume: 6
  • Issue: 3
  • Journal Name: Nano-Micro Letters
  • Publisher: OPEN ACCESS HOUSE SCIENCE & TECHNOLOGY
  • ISSN: 2150-5551
  • URL: http://www.nmletters.org/volume-6/volume-6-issue-3/item/333-preparation-of-palladium-supported-on-ferric-oxide-nano-catalysts-for-carbon-monoxide-oxidation-in-low-temperature
  • Abstract:

    Catalytic property of Pd/Fe2O3 catalysts on carbon monoxide (CO) oxidation at low temperature were investigated in this paper. Both the as-prepared and H2-pretreated Pd/Fe2O3 catalysts show catalytic performances on CO oxidation. The CO was completely converted at 333 K for the as-prepared sample, whereas at 313 K for H2-pretreated Pd/Fe2O3-573 catalyst. The catalytic performance of the Pd/Fe2O3 catalyst decreases with increased calcination temperature. This may be due to the increased crystallinity of the support and decreased metal-support interaction. Progressive deactivation of the catalysts during long-time reaction was associated with the formation of carbonates on the catalyst surface that inhibits CO activation or intermediate transformation.

  • Publish Date: Tuesday, 01 July 2014
  • Start Page: 233
  • Endpage: 241
  • DOI: 10.5101/nml140025a