Tuning Hydrogen and Carbon Nanotube Production from Phenol

Subscriber access provided by University of Newcastle, Australia

Article

Tuning hydrogen and carbon nanotube production from phenol steam reforming on Ni/Fe-based nanocatalysts Qingqing Peng, Rongli Jiang, Yongwen Tao, Huajuan Ling, Zhenyuan Wu, Zhanglei Zhu, Yuemin Zhao, Yuelun Wang, Chen Ji, Xiaozhou Liao, Anthony Vassallo, and Jun Huang ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.6b01936 • Publication Date (Web): 11 Feb 2017 Downloaded from http://pubs.acs.org on February 23, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Sustainable Chemistry & Engineering is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Sustainable Chemistry & Engineering

Tuning hydrogen and carbon nanotube production from phenol steam reforming on Ni/Fe-based nanocatalysts Qingqing Peng1, Yongwen Tao2, Huajuan Ling2, Zhenyuan Wu1, Zhanglei Zhu1, Rongli Jiang1*, Yuemin Zhao1, Yuelun Wang1, Chen Ji1, Xiaozhou Liao3, Anthony Vassallo2, Jun Huang1,2*

1

School of Chemical Engineering & Technology, China University Mining & Technology,

Xuzhou 221116, People’s Republic of China. 2

School of Chemical & Biomolecular Engineering, The University of Sydney, NSW 2006,

Australia. 3

School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney,

NSW 2006, Australia. Corresponding Authors [email protected]; [email protected];

1

ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Abstract The development of cost and environment efficient catalysts is essential to transferring phenolic compounds to valuable fuels and chemicals. Various nanocatalysts with different amount of Ni/Fe have been employed in the steam reforming of phenol, which showed high performance in terms of activity and stability. The conversion and hydrogen yield of phenol reforming over Ni/Fe-catalysts can reach 87% and 81%, respectively. The catalyst can keep its high reactivity for more than 200 h at the steam to carbon ratio(S/C) of 13.3, which is much higher than the previous report of 13 h. Using the newly developed Ni/Fe catalysts in this research, the hydrogen-rich syngas or CNT could be selectively produced via simply tuning the S/C ratio. The influence of the Ni/Fe ratio and S/C ratio on the steam reforming performance was investigated.

Keywords Phenol steam reforming; H2 production; Carbon nanotubes; Ni/Fe; Nanocatalysts; S/C

2


Page 2 of 31

Page 3 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1. Introduction The production and consumption of fuels and chemicals increases continuously with the development of modern society. Most of them are produced from fossils, including crude oil and coal that shared 33% and 30%, respectively, of the global primary energy consumption in 2013 1. Therefore, the utilization of renewable resources or recycling/reusing the wastes is essential for sustainable development. Phenolic compounds have been largely produced in petro-refining, reforming, gasification, and in some cases as tar by-products or wastes

2, 3.

In

addition, they are main compounds of the pyrolysis bio-oil in emerging bio-refining industry. It attracted lots of research interests to develop cost and environment efficient methods to transfer phenolic compounds to valuable fuels and chemicals 2, 4, 5. It has to be noted that most of phenolic compounds are produced with large amount of water, such as ca.30 wt% of phenolics with 15-30 wt% of water in pyrolysis oil 3, 6, 7. Removing water from the mixture to obtain purified phenolics by current physical and chemical methods is a cost non-effective process. Moreover, phenolic compounds are difficult for transformation due to their easy condensation inside devices and pipes accompanying with corrosion

8, 9.

It caused direct

deposition of the phenol-riched tar to the environment in most developing countries 10-13, which not only results in the waste of valuable organic carbon resources, but also pollutes the environment seriously. Therefore, it is promising to develop efficient on-site chemical processes to produce useful chemicals from the phenol-water mixture immediately after their production during gasification, reforming, or pyrolysis. Several methods have been developed such as aqueous 3



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

phase reforming

14-16,

hydrodeoxygenation

17-20,

Page 4 of 31

and steam reforming

21-25.

Among them, on-

site steam reforming can use the existing reaction system and waste heat from gasification, reforming, or pyrolysis. As involved in the reforming, the large amount of water in the mixture is used to generate steam and not necessary to be removed, which reduces the investment and operation costs. The produced hydrogen-rich syngas can be purified and transported with the existing system to be used as fuels or building blocks to produce methanol, dimethyl ether (DME) and other hydrocarbons 26. Various supported metal catalysts have been employed in steam reforming process for the higher process efficiency

27-37.

Among them, low-cost Ni catalysts were widely used, but

showed two significant challenges of sintering and coke formation 38-40. For better Ni catalysts, various supports and promoters have been introduced to enhance the dispersion of active sites and generate the support-metal interaction on catalysts, which could strongly enhance the metal activity and stability during the reactions 35, 41-43. Another strategy is to introduce small amounts of second metal to Ni catalysts to generate bimetallic catalysts

44-46.

Noble metals have been

added into Ni-based catalysts for high activity and the resistance to carbon deposition

47-50.

However, introducing Noble metal not only raised the cost of catalysts but also influenced the formation of alloy particles due to the separation of noble metal and Ni during high-temperature calcination. Using transition metal such as Fe to replace noble metals in Ni based bimetallic catalysts is an alternative method. Such a way can lead to a homogeneous dispersion of Fe atoms in bulk Ni due to the similar physical and chemical properties of the Fe and Ni metallic atoms. In this study, various amounts of Fe atoms were added to Ni/Al2O3 catalysts during synthesis via the classic co-precipitation method

51, 52.

The effect of Fe addition on catalytic

4


Page 5 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


behavior， especially on activity and carbon deposition, were investigated for the phenol reforming. It has to be mentioned that coke cannot be avoided during the phenol reforming, while the useless coke could be transferred to valuable carbon nanotube (CNT) or nanofiber when designing suitable catalysts under optimal operation condition in the gasification of solids or small alcohol reforming 37, 53-55. Using the newly developed Ni/Fe catalysts in this research, the hydrogen-rich syngas or CNT could be selectively produced via simply tuning the operation conditions. Well utilization of valuable organic carbon resource for large-scale clean energy H2 production with the high-value by-product CNT would obviously enhance the economic benefits and reduce green gas emission (burning coke during the regeneration of catalysts) for the reforming process and promote the commercial application of this sustainable technique.

2. Experimental Section

2.1 Catalyst preparation All chemicals used for the synthesis of Ni/Fe-nanocatalysts, such as Ni(NO3)2·6H2O, Fe(NO3)3·9H2O and Al(NO3)3·9H2O were obtained from Sinopharm Chemical Reagent Co. China. All catalysts were prepared by the co-precipitation method, which contain 80 mol% Al and total 20 mol% Ni/Fe with the Ni:Fe molar ratios of 10:0, 9:1, 8:2, 6:4, 5:5, 4:6, 2:8, 1:9, 0:10. The precursor solution was prepared by dissolving certain amount of Ni(NO3)2·6H2O, Fe(NO3)3·9H2O and Al(NO3)3·9H2O salts in the deionized water. NH3·H2O (25-30%) solution was dropped to the precursor solution to adjust the pH of the solution to around 8. Then, the suspension was obtained and further aged in a water bath for an hour. The suspension was 5



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

filtrated and washed by deionized water until pH reached 7. The solid product was dried at 80 oC

for 12 h and finally calcined in static air (58 L/h, 20 vol.% oxygen) at 800 oC with a heating

rate of 1 oC/min for 4 h.

2.2 Catalyst characterization The crystal structures of the prepared Ni/Fe-catalysts were investigated by X-ray diffraction (XRD, BRUKER D8 ADVANCE) using Cu-Kα radiation (λ = 1.5418 Å). The surface morphology of Ni/Fe-catalysts was examined using a Zeiss Ultra+ scanning electron microscope (SEM). Powdered specimens were spread on the SEM slabs and were sputtered with gold. Fresh and used catalysts were characterized by transmission electron microscopy (TEM) (FEI Tecnai G2 F20 operated at an acceleration voltage of 80 kV). Temperatureprogrammed reduction (TPR) of Ni/Fe-catalysts were performed on a ChemBET TPR/TPD instrument (Quantachromes) with 10% H2/Ar and a total flow rate of 20 ml/min for all samples (30 mg of each). Temperature was increased by 10 oC/min from room temperature to 1000 oC for all TPR experiments. The surface composition and electronic properties of Ni/Fe-catalysts were analyzed by Xray photoelectron spectroscopy (XPS). XPS spectra were acquired on a Thermo Fisher ESCALAB 250Xi spectrometer equipped with Al-Kα X-ray source and an X-ray spot size of 650 μm. The catalysts were reduced at 800 oC for 2 h and then exposed to air before XPS measurement, and the peak at 284.8 eV corresponding to C 1s was applied as a reference. Raman spectra were obtained for the used catalysts using a Bruker Senterra system at a wavelength of 532 nm. The main purpose of Raman was to investigate the deposited carbons 6


Page 6 of 31

Page 7 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


on the reacted Ni/Fe-catalysts.

2.3 Steam reforming The phenol (≥99.0%，solid) as reaction feed was purchased from Sinopharm Chemical Reagent Co.. The steam reforming of phenol was carried out in a fixed bed quartz reactor (i.d. 9mm) containing Ni/Fe-nanocatalysts under a continuous-flow and atmospheric pressure. The catalyst (0.15g) was diluted with quartz sands (30-40 mesh) with a ratio of 1:4. Before reforming, the catalyst was reduced in 50 vol%H2/N2 flow (30 ml min−1) at 800 oC for 2 h. After reduction, the temperature of reactor was tuned to the reaction temperature and gas flow was switched to N2 flow (stabilized in 30 min). Then, an aqueous solution of phenol (preheated at 70 oC) was pumped into a gasifier and evaporated at 200 ◦C before introducing into the fixed bed reactor via the carrier gas N2 (x% C6H5OH/y% H2O/59.5% N2). In this research, the influence of reaction temperature (600-750 oC) and the ratio of steam to carbon (S/C=0.3-13.3) were studied on the prepared catalysts. The product gas composition was analyzed by an on-line gas chromatograph (GC, FuLi 9720) equipped with TDX-01 and HP-PLOT-Q columns. The samples were simultaneously analyzed by both TCD and FID detector injected via two manual six-port valves (VICI), respectively. Based on literature

41, 56

, the calculation of hydrogen yield and phenol conversion can be

described as Eq.(1), (2) while hydrogen yield was calculated from the percentage of the stoichiometric maximum amount of hydrogen that can be produced as shown in Eq.(3), (4). Phenol conversion was defined as the number moles of carbon in the gaseous products divided by the number of moles of carbon in the feed. In this paper, we assume that steam initially react 7



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 31

with phenol in Eq.(3). And the excess steam for Eq.(3) will continue react with CO as described in Eq.(4). Therefore, when S/C ≤ 0.8, the calculation of hydrogen yield and phenol conversion based on Eq.(3), and when S/C＞0.8, the calculation of hydrogen yield and phenol conversion based on Eq.(3) and Eq.(4). When the S/C value was 0.83, there is no the excess steam react with CO in Eq.(4) ,then the CO concentration should theoretically reach the maximum, as described in Eq.(5). When the S/C was 1.8, based on Eq.(3) and Eq.(4), all the CO and steam were convert to H2 in WGS reaction, then the H2 content should reached the maximum in theory at this time, as described in Eq.(6).

H 2 yield% = Conversion% =

moles of H 2 obtained 100% stoichiometric H 2 potential

(1)

moles of carbon(in CO +CO 2 +CH 4 +C 2-3 ) obtained 100% (2) moles of carbon in the feed

C6 H5OH+5H 2O  6CO+8H 2 Endothermic

(3)

CO + H 2O  CO 2 + H 2 H 298K = - 41 kJ mol 1 n max.CO %  n max.H2 % 

6nC6 H5OH 6nC6 H5OH  8nC6 H5OH 14nC6 H5OH 14nC6 H5OH  6nC6 H5OH

(4)

 42.86%

(5)

 70.00%

(6)

3. Results and discussion

3.1 Catalyst characterization Fig. 1 shows the XRD patterns of all catalysts. Three major peaks at 37.0o, 45.0o, 65.5o (Fig. 1a-h) were observed for NiAl2O4 species (JCPDS 10-0339). With the decrease of Ni content in prepared catalysts, the intensity for NiAl2O4 species decreased as well while it still keeps dominant in XRD patterns of all Ni contained samples, which illustrates that adding Fe changed 8


Page 9 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


the particle size and crystal distortion of NiAl2O4. Obviously, the main crystal structure containing Ni in these catalysts is NiAl2O4, which was considered to be the key composition that enhanced the activity and stability in gasification/reforming peak at 2θ=37.2 o, 43.3

o

57, 58.

Meanwhile, No clear

and 62.8 o for NiO (JCPDS 78-0423) was observed in all prepared

catalysts. The peaks at 37.5 o, 45.7 o, 66.6 o were assigned to Al2O3 (JCPDS 50-0741) while there is a certain degree of overlap between the character peaks of NiAl2O4 and Al2O3 as shown in Fig.1, notably at 2θ=35-40 o and 65-70 o. The diffraction peak summit slight shift to large 2θ value at 2θ=35-40 o and 65-70 o from Fig.1a to Fig.1i. The possible reason is the NiAl2O4 diffraction peak area decreasing with the Ni loading, while the content of Al2O3 unchanged. The diffraction peaks corresponding to Fe2O3 (JCPDS 84-0310) at 24.3 o, 33.4 o, 35.8 o, 54.5 o were very hard to be observed in Fig.1, which indicates no iron oxides crystal has formed that iron was existed as amorphous iron oxide, very fine iron oxide nanoparticles or homogenous dispersed in NiAl2O4 structure. Based on Scherrer equation and the peak at 37.2 o, particle size of Ni/Fe-catalyst/1 to Ni/Fe-catalyst/9 was 7.8 nm, 7.6 nm, 7.3 nm, 6.8 nm, 6.6 nm, 6.7 nm, 6.4 nm, 3.6 nm and 3.3 nm, respectively under the assumption that composition of particles is uniform.

9



NiAl2O4

Al2O3

Fe2O3

NiAl2O4

（a）

（a）

（b）（c）

（b）（c）

Intensity (a.u.)

Intensity (a.u.)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

（d）（e）（f）（g）

（h）

（i）

（i）

20

30

40

50



60

70

80

90

Al2O3

（d）（e）（f）（g）

（h）

10

Page 10 of 31

62 63 64 65 66 67 68 69 70

o

（）



（o）

Fig. 1 XRD patterns: (a) Ni/Fe-catalyst/1 (nNi:nFe=10:0), (b) Ni/Fe-catalyst/2 (nNi:nFe=9:1), (c) Ni/Fe-catalyst/3 (nNi:nFe=8:2), (d) Ni/Fe-catalyst/4 (nNi:nFe=6:4), (e) Ni/Fe-catalyst/5 (nNi:nFe=5:5), (f) Ni/Fe-catalyst/6 (nNi:nFe=4:6), (g) Ni/Fe-catalyst/7 (nNi:nFe=2:8), (h) Ni/Fecatalyst/8 (nNi:nFe=1:9) and (i) Ni/Fe-catalyst/9 (nNi:nFe=0:10). As shown in TEM images of the nine prepared catalysts (Fig. 2), the very fine particles withuniform size of ca. 3-5 nm were homogeneously dispersed on the surface of supports (2050nm big particles). These nano-particles were aggregated into big groups with the size between 200 and 400 nm as observed in SEM images in Fig. S1(supporting information). From both TEM (Fig. 2) and SEM (Fig. S1) images, no NiO crystal was detected on all samples, which is consistent with the observation from XRD research. There was no obvious Ni and Fe particle aggregation for either catalyst, indicating the good dispersion of Ni and Fe on the Al2O3 support. A large number of roughly spherical and 10


Page 11 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


strip shaped particles were observed, which was possibly caused by the existence of Al2O3 or NiAl2O4 nano-particles 56, 58-61.

Fig. 2 TEM images: (a) Ni/Fe-catalyst/1 (nNi:nFe=10:0), (b) Ni/Fe-catalyst/2 (nNi:nFe=9:1), (c) Ni/Fe-catalyst/3 (nNi:nFe=8:2), (d) Ni/Fe-catalyst/4 (nNi:nFe=6:4), (e) Ni/Fe-catalyst/5 (nNi:nFe=5:5), (f) Ni/Fe-catalyst/6 (nNi:nFe=4:6), (g) Ni/Fe-catalyst/7 (nNi:nFe=2:8), (h) Ni/Fe-

11



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 31

catalyst/8 (nNi:nFe=1:9), (i) Ni/Fe-catalyst/9 (nNi:nFe=0:10). TPR under hydrogen has been used to investigate the reduction properties of surface metal particles on all Ni/Fe-catalyst/x as shown in Fig. 3. On the Ni/Fe-catalyst/1 (without Fe in the composition), one strong reduction peak at 700-1000 oC was detected, which is corresponding to the dominant NiAl2O4 species 62, 63. No typical H2-TPR traces of NiO crystal (300-400 oC) was observed on the surface of this catalyst 64. This finding is consistent with the XRD analysis (Fig. 1) that no crystal NiO was observed and NiAl2O4 was the dominated one in the catalyst. Even introducing Fe precursor during the synthesis, NiAl2O4 species still kept dominant in the catalysts induced by the strong reduction peak at 820 oC (Ni/Fe-catalyst/x, x=1-8), similar as results detected by XRD. On the Ni/Fe-catalyst/9 (without Ni in the composition), two reduction peaks at 410 oC and 435 oC were caused by two types of surface Fe2O3 particles based on the different particle size or locations 65, 66. However, the XRD patterns of Ni/Fe-catalyst/x do not present clear peaks assigned to Fe2O3, which are very small nanoparticles (3 nm, based on the Scherrer equation) and XRD patterns only showed broad and very weak peaks. Nearly all Fe contained catalysts have surface Fe2O3 particles as shown in Fig. 3b-i. It was reported that the hydrogen reduction of Fe2O3 requires two or three steps via Fe3O4 or Fe1-xO 67, 68. On Fe/SiO2, the H2-TPR traces exhibited two peaks at 412 and 644 oC, corresponding to two steps of Fe2O3 reduction 69. Therefore, the reduction peaks at 580-700 oC was assigned to the second step reduction of Fe2O3 particles (reduced at 410 oC and 435 oC in the first step) 70. The twostep reduction was obviously observed for high Fe contained catalysts (Fig. 3g-i) and hard to be found on catalysts with relatively low Fe amount (Fig. 3b-h). A broad shoulder at the temperature higher than 800 oC in high Fe contained catalysts (Fig. 3g-i) was possibly due to 12


Page 13 of 31

the reduction of Fe in the alumina lattice as reported elsewhere

71.

As discussed above, no

obvious reducing peak related to Fe has been detected in TPR results for Ni-rich bimetallic catalysts as shown in Fig. 3 while XRD results showed some peak shifting of NiAl2O4, which might due to the dispersion of Fe atoms into NiAl2O4 or Al2O3 lattice instead of iron oxides.

（i）（h） H2 Consumption (a.u.)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


（g）（f）（e）（d）（c）（b）（a） 200

400

600

800

1000

o

Temperature （ C）

Fig 3. TPR profiles of the samples: (a) Ni/Fe-catalyst/1 (nNi:nFe=10:0), (b) Ni/Fe-catalyst/2 (nNi:nFe=9:1), (c) Ni/Fe-catalyst/3 (nNi:nFe=8:2), (d) Ni/Fe-catalyst/4 (nNi:nFe=6:4), (e) Ni/Fecatalyst/5 (nNi:nFe=5:5), (f) Ni/Fe-catalyst/6 (nNi:nFe=4:6), (g) Ni/Fe-catalyst/7 (nNi:nFe=2:8), (h) Ni/Fe-catalyst/8 (nNi:nFe=1:9) and (i) Ni/Fe-catalyst/9 (nNi:nFe=0:10).

The main purpose of XPS was to obtain information on the surface state of the Ni/Fe13



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 31

catalysts. All the catalysts were reduced in a 20 ml/min 10% H2/He gas flow at 800 oC for 2 h before they are measured by XPS while exposed to air cannot be avoided during the operation of XPS. Fig. 4 shows the Ni 2p and Fe 2p spectra for tested catalysts. Monometallic catalysts of Ni/Fe-catalyst/1 and Ni/Fe-catalyst/9 have been tested as comparison. As presented in Fig. 4A, the minor peak (852.1 eV) corresponding to Ni0 and the larger peak (856.3 eV) assigned to Ni2+ were observed on Ni/Fe-catalyst/1, Ni/Fe-catalyst/2, Ni/Fe-catalyst/5 and Ni/Fecatalyst/6 while the intensity of these two peaks decreased with the Ni content decreasing. Even the samples have been reduced before measurement, Ni2+ still counted for majority of Ni due the fact that NiAl2O4 is hard to be reduced below 800 oC, which is consistent with TPR results. In Fig. 4B, it can be seen that the intensity of peaks corresponding to Fe2+ (709.5 eV) and Fe3+ (711.4 eV) increased with Ni/Fe ratio from 9:1 to 0:10 while Fe3+ is dominant in these samples. As discussed before in TPR results, Fe reduction will require several steps but the reducibility of Fe is much lower than Ni in prepared catalysts while comparing the H 2 consumption. It can be concluded that only a small part of Fe is existing as iron oxides in prepared samples while most of them are participating in the lattice of other particle like NiAl2O4 or Al2O3.

14


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(B)

Ni 2p

(A) 856

d

711.4

852.1

Fe 2p 709.5

Page 15 of 31

e c b

d

a c

b

880

872

864

856

736

848

728

720

712

704

B. E. (eV)

B. E. (eV)

Fig. 4 The XPS spectra in the Ni 2p (A) and Fe 2p (B) regions of the surface of several reduced catalysts. (a) Ni/Fe-catalyst/1 (nNi:nFe=10:0), (b) Ni/Fe-catalyst/2 (nNi:nFe=9:1), (c) Ni/Fecatalyst/5 (nNi:nFe=5:5), (d) Ni/Fe-catalyst/6 (nNi:nFe=4:6), (e) Ni/Fe-catalyst/9 (nNi:nFe=0:10).

3.2 Steam reforming of phenol All prepared catalysts were evaluated by the phenol reforming and their catalytic performance is summarized in Fig. 5. The primary reaction conditions such as the temperature at 700 oC and the molar ratio of water steam to amount carbon atoms of phenol S/C=13.3(0.5% C6H5OH/40% H2O/59.5% N2) were referred from previous reports as the optimal parameters for the same process

72, 73.

This work also confirmed that the optimal reaction temperature is

700 oC in the temperature range of 600 – 750 oC for the phenol reforming as shown in Fig. S2 15



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 31

in supporting information. As expected, supported Ni catalyst (Ni/Fe-catalyst/1, 85% conversion) showed much better catalytic activity than supported Fe catalyst (Ni/Fe-catalyst/9, 9.5% conversion) during the reforming. Also, Ni/Fe bimetallic catalysts with dominant amount of Fe performed much lower activity (under 10.1% phenol conversion and 9.5% H2 yield on catalysts with Ni/Fe from 4:6 to 1:9) than the catalysts containing more Ni fraction (above 77.4% phenol conversion and 55.0% H2 yield on catalysts with Ni/Fe from 5:5 to 9:1) in phenol steam reforming. This observation is consistent with previous reported work that Ni is more active than Fe in catalytic reforming process

74, 75.

However, the phenol conversion and H2 yield did

not increase continuously with Ni content in Ni/Fe-catalysts, and pure Ni catalyst was not the best catalyst in this research. H2 yield and phenol conversion reached 81.5% and 88.3% on Ni/Fe-catalyst/2 (Ni/Fe=9:1) at 700 oC, which was the best performance results among all prepared catalysts. Obviously, adding small amount of low-cost Fe for the synthesis of bimetallic catalyst could enhance the catalytic performance of metal catalysts during the catalytic reactions. It is well known that Ni-based only catalysts is easily deactivated due to serious carbon deposition in hydrocarbon steam reforming reaction, while some bimetallic Ni catalysts can dramatically improve catalysts’ resistance to carbon deposition

76, 77.

Montané

et.al. mentioned that Fe remarkably improve catalytic activity in bimetallic Ni-Fe catalysts due to the enhanced nickel dispersion and the high surface area

78, 79.

In this study, adding proper

amount of Fe into Ni-based catalysts has reduced the Ni containing particle size as well as improved Ni dispersion, which further performed higher catalytic activity in phenol steam reforming reaction. After the evaluation of prepared catalysts, Ni/Fe-catalyst/2 showed the best catalytic performance in the research and was selected for the further research. 16


Page 17 of 31

（a） 100

H2 Yield%

Phenol Conversion

(b)

H2

CO

CO2

CH4

0:10

Ni/Fe ratio of Ni/Fe-Al2O3/x catalysts

90

Conversion and H2 yield （%）

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


80 70 60 50 40 30 20 10

1:9 2:8 4:6 5:5 6:4 8:2 9:1 10:0

0

10:0 9:1

8:2

6:4

5:5

4:6

2:8

0

1:9 0:10

10

20

30

40

50

60

70

80

90

100

Outlet gas composition (mol%)

Ni/Fe ratio

Fig. 5 Influence of various catalysts on H2 yield and phenol conversion (Fig. 8a) and outlet gas composition of phenol reforming (Fig. 8b). (A) Ni/Fe-catalyst/1 (nNi:nFe=10:0), (B) Ni/Fecatalyst/2 (nNi:nFe=9:1), (C) Ni/Fe-catalyst/3 (nNi:nFe=8:2), (D) Ni/Fe-catalyst/4 (nNi:nFe=6:4), (E) Ni/Fe-catalyst/5 (nNi:nFe=5:5), (F) Ni/Fe-catalyst/6 (nNi:nFe=4:6), (G) Ni/Fe-catalyst/7 (nNi:nFe=2:8), (H) Ni/Fe-catalyst/8 (nNi:nFe=1:9) and (I) Ni/Fe-catalyst/9 (nNi:nFe=10:0), Reaction condition: T =700 oC, GHSV=60,000h-1, p=1 atm, and S/C=13.3. Catalyst loading: 0.15g.

Normally, increasing the amount of water can enhance the hydrocarbon conversion during steam reforming, such as the conversion of ethylene glycol, acetone, m-Xylene and acetol 80, 81.

In addition, excess steam in the reforming reactor could result in water gas shift reaction

(WGS) (Eq.(4)), which will further improve the hydrogen production

82-85.

The steam

reforming of phenol is an endothermic reaction while WGS is an exothermic reaction 82. The thermal energy requirement for steam reforming could be partially balanced by WGS after overloading the water amount. In this research, we adjusted the steam to carbon molar ratio (S/C) from 0.3 to 13.3 during the catalytic reforming of phenol. Moreover, we calculated the theoretical steam to carbon molar ratio (S/C) based on the reaction stoichiometry for the highest 17



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 31

CO production (S/C = 0.8(7.0% C6H5OH/33.5% H2O/59.5% N2)) and the highest H2 yield (S/C = 1.8(3.4% C6H5OH/37.1% H2O/59.5% N2)). Then the experimental results could be compared with the stoichiometric values for the deep understanding of the reforming process on catalysts. As shown in Fig 6a, the phenol conversion was significantly enhanced from 57.1-60.8% to 78.8-85.8% when the S/C increased from 0.3-0.8 to 1.3-1.8. As expected, increasing the water amount could enhance the hydrocarbon conversion during the reforming as the reaction rate should be raised simultaneously with the higher reactant concentration. Under the lower S/C ratios (0.3-1.3), H2 yield barely changed, which indicates that the reaction process was mainly based on phenol reforming. The methanation reaction from CO and H2 occurred as sidereaction and CH4 was formed as shown in Fig. 6b. Enhanced the S/C ratio higher than 0.3, steam reforming of CH4 started and CH4 fraction in the gas products was decreased. However, phenol conversion kept stable in the range of 74.1-88.3% with further increasing the S/C ratios (even 10 times higher). No strong enhancement was observed for phenol conversion, but H 2 yield increased dramatically from 30.9% to 81.5% when the S/C ratio increased from 1.8 to 13.3, which might due to the fact that phenol conversion is hard to be further improved as it is very close to completely conversion. However, increasing the water amount at this stage can still strongly enhance the WGS reaction. As shown in Fig. 6b, CO fraction was decreased with the generation of H2 and CO2 when the WGS reaction was dominated in the process. When set the S/C value to 0.8, CO concentration should theoretically reach the maximum value, our experiment result agreed with the theoretical analysis. The increase of carbon monoxide and the decrease of methane content were mainly attributed to the reaction (7) that has high reaction activity when S/C value increases from 0.3 to 0.8. When the S/C was 1.8, the 18


Page 19 of 31

H2 content should reach the maximum in theory, however the experimental result showed that H2 content became higher and CO content dropped sharply with increasing the S/C ratio. CH 4 + H 2O  CO +3H 2 H 298K = +206 kJ mol 1 （a）

H2 Yield%

100

（b）

Phenol Conversion

H2

(7)

CO

CO2

CH4

13.3 90

10.8 80

9.0

70

7.2

60

5.4

S/C


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


50

3.6

40

2.3

30

1.8 1.3

20

0.8

10

0.3

0

0.3

0.8 1.3 1.8

2.3

3.6 5.4

7.2

9.0 10.8 13.3

0

S/C

10

20

30

40

50

60

70

80

90

100


Fig. 6 Influence of steam to carbon ratio on the catalytic performance of phenol. S/C=0.8, the theoretical maximum of CO concentration. S/C=1.8, the theoretical maximum of H 2 concentration. Reaction condition: GHSV=60,000 h-1, T=700 oC, p=1 atm, t=5 h（for S/C=0.3， t=1.5 h）. Catalyst loading: Ni/Fe-catalyst/2, 0.15 g. At 700 oC and S/C=13.3, the prepared low-cost Ni/Fe-catalyst in this research (phenol conversion 88.3% and H2 yield 81.5%) showed better catalytic performance than that on highcost catalysts based on rare-earth and noble metals, such as reported Fe/50Mg-50Ce-O (63.3% conversion, 34.4% H2 yield)

72.

In addition, this catalyst showed very good stability in the

reforming as shown in Fig. 7 that phenol conversion was quite stable and H2 yield only decreased slightly in 200 h during the reaction at temperature of 700 oC and water loading of S/C=13.3. No catalyst deactivation was observed in 200 hours, which indicates the extremely good hydrothermal stability of the prepared catalysts and the high potential for industrial application. The fraction of CO was slightly increased after the first 10 h during the reaction. It might be a revised water gas shift reaction of adsorbed surface CO 2 and H2 to CO due to the 19



accumulation of CO2 and H2 products inside the reactor.

CO

CO2

H2 Yield

100

CH4

Phenol Conversion 100

90

90

80

80

70

70

60

60

50

50

40

40

30

30

20

20

10

10

0

0 0

50

100

150


H2


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 31

200

o

Time on stream (h), T=700 C

Fig. 7 The stability test of Ni/Fe-catalyst/2 for phenol steam reforming. Reaction condition: T =700 oC, GHSV=60,000 h-1, p=1 atm, and S/C=13.3. Catalyst loading: 0.15 g.

Normally, deposited coke on the surface of catalysts would also deactivate catalysts during the reforming process. In previous reports

56, 72, 73, 86 ,

the residual carbonaceous species were

observed on the catalyst bed, which were accumulated on the surface as coke and blocked the surface active sites for the reactants. The best performance catalyst in this study did not show any deactivation at 700 oC as shown in Fig. 7 and the result confirmed no carbon deposit on surface after reaction under the condition of S/C=13.3 as shown in Table 1. It was observed

20


Page 21 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


that slightly reducing the amount of water (S/C from 2.0 to 1.3) could promote the coke generation 87, 88. However, the Ni/Fe-catalyst/2 (nNi:nFe=9:1) prepared in this research showed the excellent resistance property for coke formation. After decreasing the water amount about 10 times (S/C from 13.3 to 1.3), then the coke could be obvisouly observed with 2 wt% of feed phenol as shown in Table 1. As discribed before, the hydrogen production would be decreased from 2483 to 808 Nm3/Kg phenol with the decrease of water amount. Further decrease the amount of water, more and more carbon was produced as shown in Table 1. Interestingly, TEM images indicated that the formed coke on surface were valuable carbon nanotube (CNTs) on the reacted Ni/Fe-catalyst/2. Obviously, the prepared catalyst had the unique catalytic property, which was able to swith off the formation of filamentous carbons and tune it to the fomration of valuable CNTs. CNTs have many widespride promising applications, including hydrogen storage 89-91, sensors 92, 93, and electrochemical capacitors 96.

94-

As shown in TEM, highly-purified multi-wall CNTs were obtained with diameters around

30nm. For the confirmation, Raman spectroscopy was used for the characterization of CNTs as shown in Fig.9. The peak around 1345 cm -1 (D band) corresponds to disordered carbonaceous species while the peak at about 1582 cm-1 (G band) is ascribed to tangential vibrations of the graphite carbons 97, 98. For the peak at around 2628.3 (G’ band), it should be attribute to the two-photon elastic scattering process

98, 99.

The degree of graphitization of

carbon nanotubes can be evaluated by the intensity of the D band divided by the G band (ID/IG). The ID/IG ratio of the CNTs in this research is 0.91, which was lower than the reported CNTs of 1.0 100 and the commercial CNTs of 1.25 101. The ratio of IG’/IG for CNTs produced in this research was 0.69, which is higher than the commercial one of 0.64. It indicates the phenol 21



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 31

reforming on the prepared catalyst could produce the high purity CNTs (better than commercial CNTs) as by products from useless cokes. The yield of hydrogen and CNTs can be well adjusted according to the S/C ratio as shown in Table 1. It will be very promising for industrial applications. Without changing the catalysts and other operation parameters, the production of hydrogen and CNTs can be controlled according to the energy and materials end-markets only by tuning the water amount for the reforming.

Fig. 8 the TEM of deposited carbons over Ni/Fe-catalyst/2 (nNi:nFe=9:1) after reacted 2 h at 22


Page 23 of 31

S/C=0.3 and 700 oC. Table.1 the production of carbon nanotube and hydrogen with different S/C ratio over Ni/Fecatalyst/2 at 700 oC. Carbon Nanotube

Hydrogen production

Kg/Kg phenol

Nm3/Kg phenol

0.3

0.31

247

0.8

0.12

581

1.3

0.02

808

13.3

0.00

2483

500

1000

The carbon nanotube The reacted Ni/Fe-catalyst/2

1500

2628.3/G'

1582.1/G

1344.5/D

S/C

Raman Intensity (a.u.)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


2000

2500

ID/IG

IG'/IG

0.91

0.69

1.31

0.55

3000

3500

4000

-1

Wavenumber (cm )

Fig. 9 Raman analysis of the carbon nanotube and the reacted Ni/Fe-catalyst/2

23



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 31

4. Conclusion A series of Ni/Fe-based nanocatalysts with different Ni/Fe ratio were prepared, characterized and tested on the steam reforming of phenol reaction. 700 oC has been tested as the best reaction temperature with the highest reforming activity in this study that phenol conversion and hydrogen yield reached 87% and 81%, respectively. The study of influence of S/C ratio exhibited that a lower S/C ratio tends to increase carbon monoxide yield, while a higher ratio improves hydrogen yield. In addition, CNTs has been found as the major deposited carbon at lower S/C ratio (0.3 and 0.8) after phenol reforming reaction. The maximum production of CNTs was 0.31 Kg/Kg phenol corresponded to the hydrogen production was about 247 Nm3/Kg phenol over the Ni/Fe-catalyst/2 at S/C=0.3. While at a higher S/C ratio (S/C=13.3), there was barely carbon nanotubes or other kinds of deposited carbon observed on the reacted catalysts and the hydrogen production reached the maximum value of about 2483 Nm3/Kg phenol. Considering the influence of Ni/Fe ratio of catalysts in phenol reforming reaction, adding a small amount of Fe has improved the Ni dispersion and modified catalyst reducibility, which expressed that Ni/Fe-catalyst/2 and Ni/Fe-catalyst/3 showed excellent hydrogen yield and carbon monoxide selectivity, 81% and 50%, at S/C=13.3 and 0.8, respectively. In terms of catalysts stability test, the Ni/Fe-catalyst/1 and Ni/Fe-catalyst/2 presented exceedingly high activity and hydrothermal stability after continuous run for 200 h at S/C=13.3 and 700 oC.

ASSOCIATED CONTENT Supporting Information 24


Page 25 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


The Supporting Information is available free of charge on the ACS Publications website at DOI: SEM images; Influence of reaction temperature, catalysts and steam to carbon ratio on the steam reforming of phenol AUTHOR INFORMATION Corresponding Author *Jun Huang

Email: [email protected];

*Rongli Jiang

Email: : [email protected].

Notes The authors declare no competing financial interest. ACKNOWLEDGMENTS The authors are grateful to the Natural Science Foundation of China(51674262) for their financial support.

References (1) BP. Statistical Review of World Energy June 2014. 2014, P42 (2) Zhao, C.; Kou, Y.; Lemonidou, A.A.; Li, X.B.;Lercher, J.A. Highly Selective Catalytic Conversion of Phenolic BioOil to Alkanes. Angewandte Chemie-International Edition. 2009, 48, 3987-3990. (3) Czernik, S.;Bridgwater, A. Overview of applications of biomass fast pyrolysis oil. Energy & Fuels. 2004, 18, 590598. (4) Wang, Y.; Yao, J.; Li, H.; Su, D.;Antonietti, M. Highly selective hydrogenation of phenol and derivatives over a Pd@ carbon nitride catalyst in aqueous media. J Am Chem Soc. 2011, 133, 2362-2365. (5) Liu, H.; Jiang, T.; Han, B.; Liang, S.;Zhou, Y. Selective phenol hydrogenation to cyclohexanone over a dual supported Pd-Lewis acid catalyst. Science. 2009, 326, 1250-1252. (6) Zhao, C.; He, J.Y.; Lemonidou, A.A.; Li, X.B.;Lercher, J.A. Aqueous-phase hydrodeoxygenation of bio-derived phenols to cycloalkanes. Journal of Catalysis. 2011, 280, 8-16. (7) Mohan, D.; Pittman, C.U.;Steele, P.H. Pyrolysis of Wood/Biomass for Bio-Oil: A Critical Review. Energy & Fuels. 2006, 20, 848-889. (8) Morf, P.; Hasler, P.;Nussbaumer, T. Mechanisms and kinetics of homogeneous secondary reactions of tar from continuous pyrolysis of wood chips. Fuel. 2002, 81, 843-853. (9) Constantinou, D.A.; Álvarez-Galván, M.C.; Fierro, J.L.G.;Efstathiou, A.M. Low-temperature conversion of phenol into CO, CO2 and H2 by steam reforming over La-containing supported Rh catalysts. Applied Catalysis B: Environmental. 2012, 117–118, 81-95. 25



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 31

(10) Sprynskyy, M.; Lebedynets, M.; Namiesnik, J.;Buszewski, B. Phenolics occurrence in surface water of the Dniester river basin (West Ukraine): natural background and industrial pollution. Environmental Geology. 2007, 53, 67-75. (11) Karpova, E.A.;Khramova, E.P. Phenolic composition and content of representatives of genus Spiraea L. under industrial pollution in Novosibirsk. Contemporary Problems of Ecology. 2014, 7, 228-236. (12) Shiber, J.G. Plastic particle and tar pollution on beaches of Kuwait. Environmental pollution (Barking, Essex : 1987). 1989, 57, 341-351. (13) Oostalam, B.L. Tar pollution of beaches in the Indian Ocean, the South China Sea and the South Pacific Ocean. Marine Pollution Bulletin. 1984, 15, 267-270. (14) Valenzuela, M.B.; Jones, C.W.;Agrawal, P.K. Batch aqueous-phase reforming of woody biomass. Energy & Fuels. 2006, 20, 1744-1752. (15) Huber, G.W.; Cortright, R.D.;Dumesic, J.A. Renewable Alkanes by Aqueous-Phase Reforming of BiomassDerived Oxygenates. Angewandte Chemie International Edition. 2004, 43, 1549-1551. (16) Cortright, R.; Davda, R.;Dumesic, J. Hydrogen from catalytic reforming of biomass-derived hydrocarbons in liquid water. Nature. 2002, 418, 964-967. (17) Zhao, C.; He, J.; Lemonidou, A.A.; Li, X.;Lercher, J.A. Aqueous-phase hydrodeoxygenation of bio-derived phenols to cycloalkanes. Journal of Catalysis. 2011, 280, 8-16. (18) Kim, Y.T.; Dumesic, J.A.;Huber, G.W. Aqueous-phase hydrodeoxygenation of sorbitol: A comparative study of Pt/Zr phosphate and PtReOx/C. Journal of Catalysis. 2013, 304, 72-85. (19) Hong, D.Y.; Miller, S.J.; Agrawal, P.K.;Jones, C.W. Hydrodeoxygenation and coupling of aqueous phenolics over bifunctional zeolite-supported metal catalysts. Chem. Commun. 2010, 46, 1038-1040. (20) He, J.; Zhao, C.;Lercher, J.A. Impact of solvent for individual steps of phenol hydrodeoxygenation with Pd/C and HZSM-5 as catalysts. Journal of Catalysis. 2014, 309, 362-375. (21) Fatsikostas, A.N.;Verykios, X.E. Reaction network of steam reforming of ethanol over Ni-based catalysts. Journal of Catalysis. 2004, 225, 439-452. (22) Llorca, J.; Homs, N.s.; Sales, J.;de la Piscina, P.R. Efficient production of hydrogen over supported cobalt catalysts from ethanol steam reforming. Journal of Catalysis. 2002, 209, 306-317. (23) Huber, G.W.; Iborra, S.;Corma, A. Synthesis of transportation fuels from biomass: chemistry, catalysts, and engineering. Chemical Reviews. 2006, 106, 4044-4098. (24) Trane, R.; Dahl, S.; Skjøth-Rasmussen, M.;Jensen, A. Catalytic steam reforming of bio-oil. International Journal of Hydrogen Energy. 2012, 37, 6447-6472. (25) Mortensen, P.M.; Grunwaldt, J.D.; Jensen, P.A.; Knudsen, K.;Jensen, A.D. A review of catalytic upgrading of bio-oil to engine fuels. Applied Catalysis A: General. 2011, 407, 1-19. (26) Rostrup-Nielsen, J.R. New aspects of syngas production and use. Catalysis Today. 2000, 63, 159-164. (27) Goyal, H.B.; Seal, D.;Saxena, R.C. Bio-fuels from thermochemical conversion of renewable resources: A review. Renewable and Sustainable Energy Reviews. 2008, 12, 504-517. (28) Goula, M.A.; Kontou, S.K.;Tsiakaras, P.E. Hydrogen production by ethanol steam reforming over a commercial Pd/γ-Al2O3 catalyst. Applied Catalysis B: Environmental. 2004, 49, 135-144. (29) Luo, N.; Fu, X.; Cao, F.; Xiao, T.;Edwards, P.P. Glycerol aqueous phase reforming for hydrogen generation over Pt catalyst–effect of catalyst composition and reaction conditions. Fuel. 2008, 87, 3483-3489. (30) Domine, M.E.; Iojoiu, E.E.; Davidian, T.; Guilhaume, N.;Mirodatos, C. Hydrogen production from biomassderived oil over monolithic Pt-and Rh-based catalysts using steam reforming and sequential cracking processes. Catalysis Today. 2008, 133, 565-573. (31) Graf, P.O.; Mojet, B.L.; van Ommen, J.G.;Lefferts, L. Comparative study of steam reforming of methane, 26


Page 27 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


ethane and ethylene on Pt, Rh and Pd supported on yttrium-stabilized zirconia. Applied Catalysis A: General. 2007, 332, 310-317. (32) Luo, S.; Xiao, B.; Hu, Z.; Liu, S.; Guo, X.;He, M. Hydrogen-rich gas from catalytic steam gasification of biomass in a fixed bed reactor: Influence of temperature and steam on gasification performance. International Journal of Hydrogen Energy. 2009, 34, 2191-2194. (33) Wu, H.W.; Yip, K.; Tian, F.J.; Xie, Z.L.;Li, C.Z. Evolution of Char Structure during the Steam Gasification of Biochars Produced from the Pyrolysis of Various Mallee Biomass Components. Industrial & Engineering Chemistry Research. 2009, 48, 10431-10438. (34) Wu, C.; Wang, L.; Williams, P.T.; Shi, J.;Huang, J. Hydrogen production from biomass gasification with Ni/MCM-41 catalysts: Influence of Ni content. Applied Catalysis B-Environmental. 2011, 108, 6-13. (35) Wu, C.;Williams, P.T. Hydrogen production by steam gasification of polypropylene with various nickel catalysts. Applied Catalysis B: Environmental. 2009, 87, 152-161. (36) Pirez, C.; Capron, M.; Jobic, H.; Dumeignil, F.;Jalowiecki-Duhamel, L. Highly Efficient and Stable CeNiHZOY Nano-Oxyhydride Catalyst for H2 Production from Ethanol at Room Temperature. Angewandte Chemie International Edition. 2011, 50, 10193-10197. (37) Fang, W.; Pirez, C.; Capron, M.; Paul, S.; Raja, T.; Dhepe, P.L.; Dumeignil, F.;Jalowiecki-Duhamel, L. Ce–Ni mixed oxide as efficient catalyst for H2 production and nanofibrous carbon material from ethanol in the presence of water. Rsc Advances. 2012, 2, 9626-9634. (38) Christensen, K.O.; Chen, D.; Lødeng, R.;Holmen, A. Effect of supports and Ni crystal size on carbon formation and sintering during steam methane reforming. Applied Catalysis A: General. 2006, 314, 9-22. (39) Das, S.; Thakur, S.; Bag, A.; Gupta, M.S.; Mondal, P.;Bordoloi, A. Support interaction of Ni nanocluster based catalysts applied in CO2 reforming. Journal of Catalysis. 2015, 330, 46-60. (40) Zhou, L.; Li, L.; Wei, N.; Li, J.;Basset, J.M. Effect of NiAl2O4 Formation on Ni/Al2O3 Stability during Dry Reforming of Methane. ChemCatChem. 2015, 7, 2508-2516. (41) Matas Güell, B.; Babich, I.V.; Lefferts, L.;Seshan, K. Steam reforming of phenol over Ni-based catalysts-A comparative study. Applied Catalysis B: Environmental. 2011, 106, 280-286. (42) Wu, C.; Dong, L.; Onwudili, J.; Williams, P.T.;Huang, J. Effect of Ni particle location within the mesoporous MCM-41 support for hydrogen production from the catalytic gasification of biomass. Acs Sustainable Chemistry & Engineering. 2013, 1, 1083-1091. (43) Lovell, E.; Jiang, Y.; Scott, J.; Wang, F.; Suhardja, Y.; Chen, M.; Huang, J.;Amal, R. CO 2 reforming of methane over MCM-41-supported nickel catalysts: altering support acidity by one-pot synthesis at room temperature. Applied Catalysis A: General. 2014, 473, 51-58. (44) Broda, M.; Kierzkowska, A.M.; Baudouin, D.; Imtiaz, Q.; Copéret, C.;Müller, C.R. Sorbent-Enhanced Methane Reforming over a Ni-Ca-Based, Bifunctional Catalyst Sorbent. ACS Catalysis. 2012, 2, 1635-1646. (45) Bimbela, F.; Chen, D.; Ruiz, J.; García, L.;Arauzo, J. Ni/Al coprecipitated catalysts modified with magnesium and copper for the catalytic steam reforming of model compounds from biomass pyrolysis liquids. Applied Catalysis B: Environmental. 2012, 119, 1-12. (46) Ashok, J.;Kawi, S. Nickel-Iron Alloy Supported over Iron-Alumina Catalysts for Steam Reforming of Biomass Tar Model Compound. ACS Catalysis. 2013, 4, 289-301. (47) Rodriguez, J. Physical and chemical properties of bimetallic surfaces. Surface Science Reports. 1996, 24, 223287. (48) Zhang, J.; Wang, Y.; Ma, R.;Wu, D. Characterization of alumina-supported Ni and Ni-Pd catalysts for partial oxidation and steam reforming of hydrocarbons. Applied Catalysis A: General. 2003, 243, 251-259. (49) Choudhary, V.R.; Prabhakar, B.;Rajput, A.M. Beneficial Effects of Noble Metal Addition to Ni/Al 2O3 Catalyst 27



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 31

for Oxidative Methane-to-Syngas Conversion. Journal of Catalysis. 1995, 157, 752-754. (50) Cruz Sanchez-Sanchez, M.; Navarro Yerga, R.M.; Kondarides, D.I.; Verykios, X.E.;Fierro, J.L.G. Mechanistic Aspects of the Ethanol Steam Reforming Reaction for Hydrogen Production on Pt, Ni, and PtNi Catalysts Supported on gamma-Al2O3. Journal of Physical Chemistry A. 2010, 114, 3873-3882. (51) Narayanan, S.;Unnikrishnan, R. Acetone hydrogenation over co-precipitated Ni/Al2O3, Co/Al2O3 and Fe/Al2O3 catalysts. J. Chem. Soc., Faraday Trans. 1998, 94, 1123-1128. (52) Wang, G.; Jin, Y.; Liu, G.;Li, Y. Production of hydrogen and nanocarbon from catalytic decomposition of methane over a Ni–Fe/Al2O3 catalyst. Energy & Fuels. 2013, 27, 4448-4456. (53) Taboada, C.D.; Batista, J.; Pintar, A.;Levec, J. Preparation, characterization and catalytic properties of carbon nanofiber-supported Pt, Pd, Ru monometallic particles in aqueous-phase reactions. Applied Catalysis BEnvironmental. 2009, 89, 375-382. (54) Wu, C.F.; Huang, J.;Williams, P.T. Carbon nanotubes and hydrogen production from the reforming of toluene. International Journal of Hydrogen Energy. 2013, 38, 8790-8797. (55) Wu, C.F.; Nahil, M.A.; Miskolczi, N.; Huang, J.;Williams, P.T. Processing Real-World Waste Plastics by PyrolysisReforming for Hydrogen and High-Value Carbon Nanotubes. Environ Sci Technol. 2014, 48, 819-826. (56) Wang, S.; Cai, Q.; Zhang, F.; Li, X.; Zhang, L.;Luo, Z. Hydrogen production via catalytic reforming of the biooil model compounds: Acetic acid, phenol and hydroxyacetone. International Journal of Hydrogen Energy. 2014, 39, 18675-18687. (57) Xu, Z.; Li, Y.; Zhang, J.; Chang, L.; Zhou, R.;Duan, Z. Bound-state Ni species—a superior form in Ni-based catalyst for CH4/CO2 reforming. Applied Catalysis A: General. 2001, 210, 45-53. (58) Salhi, N.; Boulahouache, A.; Petit, C.; Kiennemann, A.;Rabia, C. Steam reforming of methane to syngas over NiAl2O4 spinel catalysts. International Journal of Hydrogen Energy. 2011, 36, 11433-11439. (59) Lee, J.H.; Hwang, K.S.; Jang, S.P.; Lee, B.H.; Kim, J.H.; Choi, S.U.S.;Choi, C.J. Effective viscosities and thermal conductivities of aqueous nanofluids containing low volume concentrations of Al2O3 nanoparticles. International Journal of Heat and Mass Transfer. 2008, 51, 2651-2656. (60) Centeno, M.A.; Paulis, M.; Montes, M.;Odriozola, J.A. Catalytic combustion of volatile organic compounds on Au/CeO2/Al2O3 and Au/Al2O3 catalysts. Applied Catalysis A: General. 2002, 234, 65-78. (61) Sahli, N.; Petit, C.; Roger, A.C.; Kiennemann, A.; Libs, S.;Bettahar, M.M. Ni catalysts from NiAl 2O4 spinel for CO2 reforming of methane. Catalysis Today. 2006, 113, 187-193. (62) Roh, H.S.; Jun, K.W.;Park, S.E. Methane-reforming reactions over Ni/Ce-ZrO2/θ-Al2O3 catalysts. Applied Catalysis A: General. 2003, 251, 275-283. (63) Li, G.; Hu, L.;Hill, J.M. Comparison of reducibility and stability of alumina-supported Ni catalysts prepared by impregnation and co-precipitation. Applied Catalysis A: General. 2006, 301, 16-24. (64) Boukha, Z.; Jiménez-González, C.; de Rivas, B.; González-Velasco, J.R.; Gutiérrez-Ortiz, J.I.;López-Fonseca, R. Synthesis, characterisation and performance evaluation of spinel-derived Ni/Al2O3 catalysts for various methane reforming reactions. Applied Catalysis B: Environmental. 2014, 158–159, 190-201. (65) Lin, H.Y.; Chen, Y.W.;Li, C. The mechanism of reduction of iron oxide by hydrogen. Thermochimica Acta. 2003, 400, 61-67. (66) Gillot, B.; Tyranowicz, J.;Rousset, A. Study of the oxidation kinetics of finely divided magnetites. I. Influence of substitution by aluminium. Materials Research Bulletin. 1975, 10, 775-782. (67) Pineau, A.; Kanari, N.;Gaballah, I. Kinetics of reduction of iron oxides by H 2: Part I: Low temperature reduction of hematite. Thermochimica Acta. 2006, 447, 89-100. (68) Pineau, A.; Kanari, N.;Gaballah, I. Kinetics of reduction of iron oxides by H 2: Part II. Low temperature reduction of magnetite. Thermochimica Acta. 2007, 456, 75-88. 28


Page 29 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(69) Zhang, C.H.; Wan, H.J.; Yang, Y.; Xiang, H.W.;Li, Y.W. Study on the iron–silica interaction of a co-precipitated Fe/SiO2 Fischer–Tropsch synthesis catalyst. Catalysis Communications. 2006, 7, 733-738. (70) Lingaiah, N.; Sai Prasad, P.S.; Rao, P.K.; Smart, L.E.;Berry, F.J. Studies on magnesia supported mono- and bimetallic Pd-Fe catalysts prepared by microwave irradiation method. Applied Catalysis A: General. 2001, 213, 189-196. (71) Park, J.Y.; Lee, Y.J.; Khanna, P.K.; Jun, K.W.; Bae, J.W.;Kim, Y.H. Alumina-supported iron oxide nanoparticles as Fischer-Tropsch catalysts: Effect of particle size of iron oxide. Journal of Molecular Catalysis a-Chemical. 2010, 323, 84-90. (72) Polychronopoulou, K.; Bakandritsos, A.; Tzitzios, V.; Fierro, J.L.G.;Efstathiou, A.M. Absorption-enhanced reforming of phenol by steam over supported Fe catalysts. Journal of Catalysis. 2006, 241, 132-148. (73) Polychronopoulou, K.; Costa, C.N.;Efstathiou, A.M. The steam reforming of phenol reaction over supportedRh catalysts. Applied Catalysis A: General. 2004, 272, 37-52. (74) Hegarty, M.E.S.; O'Connor, A.M.;Ross, J.R.H. Syngas production from natural gas using ZrO2-supported metals. Catalysis Today. 1998, 42, 225-232. (75) Murata, K.; Wang, L.; Saito, M.; Inaba, M.; Takahara, I.;Mimura, N. Hydrogen Production from Steam Reforming of Hydrocarbons over Alkaline-Earth Metal-Modified Fe- or Ni-Based Catalysts. Energy & Fuels. 2004, 18, 122-126. (76) Liu, D.; Xian, Y.Q.; Wei, N.E.C.; Lau, R.; Borgna, A.;Yang, Y. MCM-41 supported nickel-based bimetallic catalysts with superior stability during carbon dioxide reforming of methane: Effect of strong metal-support interaction. Journal of Catalysis. 2009, 266, 380-390. (77) Chin, Y.H.; King, D.L.; Roh, H.S.; Wang, Y.;Heald, S.M. Structure and reactivity investigations on supported bimetallic Au Ni catalysts used for hydrocarbon steam reforming. Journal of Catalysis. 2006, 244, 153-162. (78) Bolshak, E.; Abelló, S.;Montané, D. Ethanol steam reforming over Ni–Fe-based hydrotalcites: Effect of iron content and reaction temperature. International Journal of Hydrogen Energy. 2013, 38, 5594-5604. (79) Abelló, S.; Bolshak, E.;Montané, D. Ni-Fe catalysts derived from hydrotalcite-like precursors for hydrogen production by ethanol steam reforming. Applied Catalysis A General. 2013, 450, 261-274. (80) Ramos, M.C.; Navascues, A.I.; Garcia, L.;Bilbao, R. Hydrogen production by catalytic steam reforming of acetol, a model compound of bio-oil. Industrial & Engineering Chemistry Research. 2007, 46, 2399-2406. (81) Hu, X.;Lu, G. Investigation of the steam reforming of a series of model compounds derived from bio-oil for hydrogen production. Applied Catalysis B-Environmental. 2009, 88, 376-385. (82) Ertl G., Knoezinger H., Schueth F., Weitkamp J, Eds. Handbook of Heterogeneous Catalysis; Wiley-VCH Verlag GmbH: Weinheim, Germany, 2008. (83) Trane, R.; Dahl, S.; Skjøth-Rasmussen, M.S.;Jensen, A.D. Catalytic steam reforming of bio-oil. International Journal of Hydrogen Energy. 2012, 37, 6447-6472. (84) Rostrup-Nielsen, J.R.; Sehested, J.;Nørskov, J.K. Hydrogen and synthesis gas by steam- and C02 reforming. In: Advances in Catalysis, Academic Press, 2002, 47, 65-139. (85) Palo, D.R.; Dagle, R.A.;Holladay, J.D. Methanol Steam Reforming for Hydrogen Production. Chemical Reviews. 2007, 38, 3992-4021. (86) Polychronopoulou, K.; Fierro, J.L.G.;Efstathiou, A.M. The phenol steam reforming reaction over MgO-based supported Rh catalysts. Journal of Catalysis. 2004, 228, 417-432. (87) Coll, R.; Salvado, J.; Farriol, X.;Montane, D. Steam reforming model compounds of biomass gasification tars: conversion at different operating conditions and tendency towards coke formation. Fuel Processing Technology. 2001, 74, 19-31. (88) Bartholomew, C.H. Carbon deposition in steam reforming and methanation. Catalysis Reviews Science and 29



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 30 of 31

Engineering. 1982, 24, 67-112. (89) Liu, C.; Fan, Y.Y.; Liu, M.; Cong, H.T.; Cheng, H.M.;Dresselhaus, M.S. Hydrogen storage in single-walled carbon nanotubes at room temperature. Science. 1999, 286, 1127-1129. (90) Dillon, A.C.; Jones, K.M.; Bekkedahl, T.A.; Kiang, C.H.; Bethune, D.S.;Heben, M.J. Storage of hydrogen in single-walled carbon nanotubes. Nature. 1997, 386, 377-379. (91) Arico, A.S.; Bruce, P.; Scrosati, B.; Tarascon, J.M.;Van Schalkwijk, W. Nanostructured materials for advanced energy conversion and storage devices. Nature Materials. 2005, 4, 366-377. (92) Zhao, Q.; Gan, Z.H.;Zhuang, Q.K. Electrochemical sensors based on carbon nanotubes. Electroanalysis. 2002, 14, 1609-1613. (93) Barone, P.W.; Baik, S.; Heller, D.A.;Strano, M.S. Near-infrared optical sensors based on single-walled carbon nanotubes. Nature Materials. 2005, 4, 86-U16. (94) Zhu, Y.; Murali, S.; Stoller, M.D.; Ganesh, K.J.; Cai, W.; Ferreira, P.J.; Pirkle, A.; Wallace, R.M.; Cychosz, K.A.; Thommes, M.; Su, D.; Stach, E.A.;Ruoff, R.S. Carbon-Based Supercapacitors Produced by Activation of Graphene. Science. 2011, 332, 1537-1541. (95) Frackowiak, E.;Beguin, F. Carbon materials for the electrochemical storage of energy in capacitors. Carbon. 2001, 39, 937-950. (96) Baughman, R.H.; Zakhidov, A.A.;de Heer, W.A. Carbon nanotubes - the route toward applications. Science. 2002, 297, 787-792. (97) DiLeo, R.A.; Landi, B.J.;Raffaelle, R.P. Purity assessment of multiwalled carbon nanotubes by Raman spectroscopy. Journal of Applied Physics. 2007, 101, 064307. (98) Wu, C.; Wang, Z.; Williams, P.T.;Huang, J. Renewable hydrogen and carbon nanotubes from biodiesel waste glycerol. Sci Rep. 2013, 3. (99) Saito, R.; Gruneis, A.; Samsonidze, G.G.; Brar, V.W.; Dresselhaus, G.; Dresselhaus, M.S.; Jorio, A.; Cancado, L.G.; Fantini, C.; Pimenta, M.A.;Souza, A.G. Double resonance Raman spectroscopy of single-wall carbon nanotubes. New Journal of Physics. 2003, 5, 157. (100) Cui, S.; Canet, R.; Derre, A.; Couzi, M.;Delhaes, P. Characterization of multiwall carbon nanotubes and influence of surfactant in the nanocomposite processing. Carbon. 2003, 41, 797-809. (101) Stefov, V.; Najdoski, M.; Bogoeva-Gaceva, G.;Buzarovska, A. Properties assessment of multiwalled carbon nanotubes: A comparative study. Synthetic Metals. 2014, 197, 159-167.

30


Page 31 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Table of Contents Tuning hydrogen and carbon nanotube production from phenol steam reforming on Ni/Fe-based nanocatalysts Qingqing Peng, Yongwen Tao, Huajuan Ling, Zhenyuan Wu, Zhanglei Zhu, Rongli Jiang*, Yuemin Zhao, Yuelun Wang, Chen Ji, Xiaozhou Liao, Anthony Vassallo, Jun Huang*

SYNOPSIS: Phenol and steam reacted on Ni/Fe-based nanocatalysts(phenol steam reforming reaction) and produced a large amount of hydrogen and carbon nanotubes by tuning the steam to carbon ratio(S/C)

31


Tuning Hydrogen and Carbon Nanotube Production from Phenol

Recommend Documents