KIT-6

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Catalytic Upgrading of Bio-Oil over Cu/MCM-41 and Cu/KIT-6 Prepared by #-Cyclodextrin-assisted Co-Impregnation Method Surachai Karnjanakom, Guoqing Guan, Bayu Asep, Xiaogang Hao, Suwadee Kongparakul, Chanatip Samart, and Abuliti Abudula J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.5b11840 • Publication Date (Web): 28 Jan 2016 Downloaded from http://pubs.acs.org on January 31, 2016

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The Journal of Physical Chemistry

Catalytic Upgrading of Bio-Oil over Cu/MCM-41 and Cu/KIT-6 Prepared by β-Cyclodextrin-Assisted Co-Impregnation Method

Surachai Karnjanakom,1 Guoqing Guan,*,1,2 Bayu Asep,1 Xiaogang Hao,3 Suwadee Kongparakul,4 Chanatip Samart,4 Abuliti Abudula1,2

1

Graduate School of Science and Technology, Hirosaki University, 1-Bunkyocho, Hirosaki 036-8560, Japan

2

North Japan Research Institute for Sustainable Energy (NJRISE), Hirosaki University, 2-1-3, Matsubara, Aomori 030-0813, Japan

3

Department of Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China 4

Department of Chemistry, Faculty of Science and Technology, Thammasat University, Pathumtani 12120 Thailand

*Corresponding author. Tel.: +81-17-762-7756; Fax: +81-17-735-5411 Email-address: [email protected] (G. Guan)

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ABSTRACT: Cu loaded MCM-41 and KIT-6 are prepared by β-cyclodextrin (CD) assisted co-impregnation method (Cu/MCM-41-CD and Cu/KIT-6-CD) for in situ catalytic upgrading of bio-oil derived from the fast pyrolysis of biomass. It is found that Cu/MCM-41-CD and Cu/KIT-6-CD exhibit higher catalytic activity for promoting the deoxygenation from the biooil when compared with those prepared by conventional impregnation method. 20 wt.% of Cu loaded MCM-41-CD and KIT-6-CD shows the highest catalytic activity, by which the upgraded bio-oil is rich in monocyclic aromatic hydrocarbons such as benzene, toluene and xylene with the total relative maximum hydrocarbon amount of 73.2% and 86.1%. After reuse of the regenerated catalyst for four cycles, no serious reduction of total relative hydrocarbon amount is found. The possible upgrading mechanism is proposed. It is expected to provide a new direction with a green method for development of the catalyst for the upgrading of bio-oil.


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INTRODUCTION Renewable energy is becoming more and more attractive with the rapid decrease of fossil fuels and the increase of environment problems.1,2 Currently, lignocellulosic biomass is one of promising renewable energy resources of low cost.3 The conversion of lignocellulosic biomass into convenient energy fuels via thermochemical technologies such as torrefaction,

gasification and slow or fast pyrolysis is widely utilized.4,5 Fast pyrolysis process is considered as the useful technology for bio-oil production with a high yield. In general, this process is carried out at intermediate temperatures controlled in the range of 300 to 600 °C under atmospheric pressure with a heating rate as high as 1000 °C/min in the absence of oxygen, by which cellulose, hemicellulose and lignin in the lignocellulosic biomass can be converted to bio-oil containing various high value-added chemicals such as benzene, toluene and xylene (BTX).6-8 However, due to the complex and dense structures of the components such as lignin in biomass, the actual yield of bio-oil obtained from fast pyrolysis is still not so high. Thus, pretreatment of biomass before the pyrolysis is considered as one of the best ways to obtain high yield of bio-oil. To date, chemical treatment of biomass by using organic/inorganic acid, base, ionic liquid and ozonolysis have been widely investigated.9,10 However, the used toxic chemicals are difficult to recycle or dispose. Recently, ultrasonic pretreatment of biomass is revealed as a green method to efficiently destroy the biomass structure to “open” structure and as such, the bio-oil yield can be increased by without using any toxic chemicals. Seino et al.11 found that the ultrasound pretreatment can cause the opening up of α-O-4 and β-O-4 linkages in lignin, decrease crystalline structure of cellulose, resulting in that the biomass can be more easily decomposed and thus more bio-oil can be produced. In our previous study, by pretreatment of cedar wood using ultrasound before pyrolysis, the yield of bio-oil was increased about 10 wt%.12 On the other hand, bio-oil derived from the fast pyrolysis of biomass usually contains 3 ACS Paragon Plus Environment


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high oxygen content with high corrosiveness and low heating value.13 Thus, it is necessary to be upgraded prior to using as transportation fuels. The conventional upgrading method is hydro-deoxygenation (HDO) with high pressure hydrogen in the presence of catalysts.14 However, this method is not satisfactory due to its high operation cost together with substantial hydrogen consumption. Zeolites exhibit high catalytic activity for the conversion of oxygenated compounds to hydrocarbons via deoxygenating reactions such as decarboxylation, decarbonylation, dehydration, oligomerization, dehydrogenation, catalytic cracking, aromatization and others.15 Du et al.16 found that HZSM-5 has higher catalytic activity than other kinds of zeolites for promoting the deoxygenation, giving the rich aromatic hydrocarbons. However, pore size of zeolite is limited, so those components with large molecule size in bio-oil cannot enter the zeolite pores.17 To solve this problem, Kaewpengkrow et al.18 developed alumina, zirconia and titania based catalysts with high surface areas and larger pore sizes to reduce the acids, phenols, ketones and sugars and increase hydrocarbons in the bio-oil. Recently, some metals such as Mg, Ni, Cu, Ga, Fe, Co, Pd and Mo are loaded on the porous materials for the deoxygenation reaction.18-21 Among them, Cu shows the similar catalytic activity on deoxygenation as some noble metals such as Pt, Pd and Ru. However, some problems such as coke deposition and pore blockage are usually found in metal-loaded porous supports. It is reported that the sintering of supported metals during the thermal treatment period easily occurs when the support materials have low surface areas and narrow pore sizes.22 In recent years, mesoporous silica materials such as MCM-41, KIT-6, SBA-15 and HMS have been attracted great interests since they have potentials to convert the large molecules in the bio-oils when they are used as catalysts or catalyst supports.23 Among them, MCM-41 and KIT-6 are two most promising mesoporous materials. MCM-41 has onedimensional, homogeneous and hexagonal pore arrays with mesoporous pore diameters


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ranging from about 2 to 4 nm and high specific surface area over 1000 m2/g.24 In contrast, KIT-6 material has a three-dimensional, cubic and Ia3d symmetric structure with interpenetrating bi-continuous network of channels.25 Due to the highly opened spaces as well as unique 3D channel networks, large molecules or metal species can more easily diffuse inside the structure of KIT-6 without blockage. Thus, KIT-6 should be more suitable as the catalyst support for loading high concentration of metal for large molecule conversion. Szegedi et al.26 reported that a concentration as high as 20 wt.% of Co can be well loaded on MCM-41 and SBA-15 without sintering. Higher metal loading on the support with well dispersion as well as small particle size is expected to improve the catalytic activity and stability. Recently, it is found that ethylene glycol (EG) assisted impregnation of metal on MCM-41 can obtain more uniform and smaller metal particles on MCM-41 due to the redistribution of active phase on the support structure and as a result, the coking is effectively resisted during the reaction.27,28 However, EG is a toxic chemical and during the removal of EG, some toxic species are also exhausted. To solve this problem in this study, cyclodextrin (CD), a naturally available green material, was used to replace EG for the assistance of Cu particles to disperse on MCM-41 and KIT-6. The performances of the as-prepared catalysts were tested for the upgrading of bio-oil derived from the fast pyrolysis of ultrasonic-pretreated cedar. The catalysts were characterized by BET surface measurement, X-ray diffractometer (XRD), scanning electron microscope coupled with energy dispersive X-ray detector (SEM-EDX), H2-Temperatureprogrammed reduction (H2-TPR) and NH3-Temperature-programmed desorption (NH3-TPD) in order to investigate their physicochemical properties. Long-term stability of the catalysts after regeneration and without regeneration was also investigated. It is expected that the upgraded bio-oil containing more hydrocarbons in one-step can be obtained by using the presented process with Cu/MCM-41-CD or Cu/KIT-6-CD as the catalyst.



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EXPERIMENTAL Biomass Materials. Cedar wood was collected from Aomori, Japan and used as biomass feedstock in this study. It was crushed and sieved with a size in the range of 0.85-1 mm and dried at 105 °C. Proximate analysis such as moisture, volatile matter, ash and fixed carbon of cedar wood was determined according to ASTM D7582 standard. Ultimate analysis was carried out to determine the elemental compositions, i.e., C, H, N, S and O, by using an elemental analyzer (Vario EL cube elemental analyzer). Ash composition was analyzed using an energy dispersive X-ray spectrometer (EDX-800HS, Shimadzu, Japan). The results of proximate, ultimate and ash composition are shown in Table S1 in supporting information (SI). Ultrasonic Pretreatment of Biomass. 2 g of as-prepared cedar wood was moistened with 50 mL of distilled water and pre-treated in an ultrasonic bath (USD-1R, AS ONE) under a frequency of 40 kHz with a power of 150 W for 200 min, which is the optimum conditions in our preliminary experiments. Thereafter, the mixture solution was evaporated at 80 °C for removal of water and then dried at 105 °C overnight in oven. The ultrasonic pre-treated cedar wood was used as the feedstock for the fast pyrolysis. Catalyst Preparation. MCM-41 was synthesized using the procedure reported by Roik and Belyakova.24 In a typical synthesis process, 7.3 g of cetyltrimethylammonium bromide (CTAB, Wako, Japan) was dissolved in 260 mL of deionized water and mixed with 32.4 mL of ethanol (EtOH, Wako, Japan) under stirring at 35 °C for 30 min. After complete dissolution, 20.9 mL of ammonia (NH4OH, Kanto Chemical, Japan) was added and followed by adding 22.3 mL of tetraethyl orthosilicate (TEOS, Wako, Japan), and remained at 35 °C under stirring for 2 h. Herein, the initial composition in the synthesis is 0.1TEOS: 0.02CTAB: 2.4NH4OH: 5.2EtOH: 14.4H2O. The final gel was transferred to a Teflon-lined stainless steel 6 ACS Paragon Plus Environment

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autoclave and heated at 100 °C for 24 h. Finally, the precipitated white product of MCM-41 was filtered, washed with deionized water, dried at 105 °C in oven and then calcined at 550 °C in air for 4 h. KIT-6 was synthesized by following the published procedure.25 In a typical synthesis process, 6 g of Pluronic P123 (P123, Aldrich, Germany) was dissolved in a solution containing 217 mL of deionized water and 10 mL of hydrochloric acid (37% HCl, Wako, Japan) and then stirred at 35 °C until the solution became clear. After completely dissolved, 6 g of 1-butanol (BuOH, Wako, Japan) was added and the solution was continuously stirred for 1 h. Then, 13.8 mL of TEOS was added and the resulting mixture was kept at 35 °C under stirring for 24 h. Herein, the initial composition in the synthesis is 0.1TEOS: 0.0053P123: 0.184HCl: 0.13BuOH: 19.4H2O. The gel was transferred to a Teflon-lined stainless steel autoclave and heated at 100 °C for 24 h. Finally, the precipitated product of KIT-6 was filtered, washed with deionized water, dried at 105 °C in oven and then calcined at the similar temperature as that for MCM-41. Cu was loaded on MCM-41 or KIT-6 with loading amounts of 5, 10, 20 and 30 wt.% were prepared by CD-assisted co-impregnation method. In short, a certain amount of Cu(NO3)2.3H2O and β-cyclodextrin (Wako, Japan) were dissolved together with a molar ratio of Cu:CD = 50:1 in deionized water. Then MCM-41 or KIT-6 powder was added in the mixture solution and stirred at ambient temperature for 2 h. Thereafter, the slurry was dried at 80 °C and then calcined at 550 °C in air atmosphere for 4 h. The obtained catalysts are named as Cu/MCM-41-CD and Cu/KIT-6-CD. For comparison, Cu/MCM-41 and Cu/KIT-6 (without CD assistance) were also prepared by the conventional impregnation method. Catalyst Characterization. Specific BET surface area, pore volume and pore diameter of catalyst were determined by N2 adsorption-desorption using a Quantachrome instrument (NOVA 4200e, USA). Crystalline structure of catalyst was examined by a X-ray



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diffractometer (XRD, Rigaku Smartlab, Japan) in the 2θ range of 30 to 90° with a scanning step of 0.02° using Cu Kα radiation (λ = 0.1542 nm). The surface morphology of catalyst was observed with a scanning electron microscope (SEM, SU8010, Hitachi, Japan) coupled with energy dispersive X-ray detector (EDX). TEM images were obtained using a JEM-2100F transmission electron microscope (TEM, JEOL, Japan) operating at 200 kV. Reduction behavior and acidity of the catalyst were determined by H2-Temperature-programmed reduction (H2-TPR) and NH3-Temperature-programmed desorption (NH3-TPD), respectively, using a BET-CAT catalyst analyzer (BEL, Japan). The coke deposition amount on catalyst was determined using a thermogravimatric analyzer (TGA, DTG-60H, Shimadzu, Japan) with a heating rate of 10 °C/min until a temperature of 800 ºC under air flow. Catalytic Upgrading of Bio-Oil. All experiments were carried out in a fixed bed reactor using N2 flow (100 cm3/min) as the carrier gas. The schematic diagram of the experimental setup for catalytic upgrading of bio-oil derived from the fast pyrolysis of biomass is shown in Figure S1. At the beginning, N2 gas was flowed into the reactor for about 10 min to move out the inside air. In a typical run, 0.1 g of biomass and 0.6 g of catalyst were separately packed with quartz wool in the reactor. The fast pyrolysis reaction temperature, reaction time and heating rate were fixed at 565 ºC, 4 min and 1000 ºC/min, respectively, which is the optimum conditions to obtain the highest bio-oil yield in our preliminary experiments. The bio-oil product was trapped by acetone in ice-cooling bottle and the noncondensed gas was purified and collected in a gas bag for further analysis. Analysis of Bio-Oil and Gas Products. The collected bio-oil was analyzed with a gas chromatography (GC-2010 Plus, Shimadzu, Japan)/mass spectrometry (GCMS-QP2010 Ultra, Shimadzu, Japan) with Ultra ALLOY+ 5 capillary column. The bio-oil sample was injected into the column using auto injection mode where the temperature was increased from 50 to 300 °C with a ramp rate 10 °C/min and held at 300 °C for 10 min. The ionization


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chamber of MS setup was set at 200 °C. Various peaks in chromatogram corresponding to various compounds such as aromatics, aliphatics, phenols, ketones, aldehydes, furans, sugars, acids and others were identified by comparison with the built-in NIST spectral library. Here, the products with boiling points lower than 300 °C can be detected for further analysis. The water content in bio-oil was measured using Karl-Fisher Titration method (MKS-500, KEM, Japan). The collected non-condensed gas was analyzed off-line using a gas chromatography (Agilent 7890A GC system, USA) equipped with thermal conductivity detector (TCD) and 3 packed columns (1 molecular sieve 5A column + 1 HayeSep Q column + 1 molecular sieve 5A column) for separation of CO, CH4 and CO2 using He as a carrier gas, while a molecular sieve 5 A for H2 detection using Ar as a carrier gas.

RESULTS AND DISCUSSION Characterization of Catalyst. Figure 1 shows the N2 adsorption-desorption isotherms and pore size distributions of various prepared catalysts. Figures 1A and C exhibit the type IV isotherms with a hysteresis loop based on the IUPAC classification for order mesoporous structure, which are the characteristic properties of MCM-41 and KIT-6 materials.24,25 The sharpness of isotherm with the characteristic of capillary condensation in each sample corresponds to the narrow uniform distribution of pore size (Figures 1B and D). In comparison, 5-30 wt.% Cu/MCM-41-CD samples have narrower pore size distributions with an average pore size of about 2.2 nm than 5-30 wt.% Cu/KIT-6-CD samples with an average pore size of about 5.2 nm.



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Figure 1. (A) N2 adsorption-desorption isotherms and (B) pore-size distributions of 5-30 wt.% Cu/MCM-41-CD, (C) N2 adsorption-desorption isotherms and (D) pore-size distributions of 5-30 wt.% Cu/KIT-6-CD. The textural properties of catalysts are summarized in Table 1. It can be seen that 5-30 wt.% Cu/MCM-41 samples possess higher surface areas (780-380 m2/g) than 5-30 wt.% Cu/KIT-6 (about 570-265 m2/g). Moreover, BET surface area and pore volume significantly decrease with the increase in Cu loading amount, suggesting that surface and pore structures of the supports are partly covered and occupied by the dispersed Cu species.


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Table 1. Physicochemical Properties of As-Prepared Catalysts Surface Pore Pore size Acidity Catalyst area volume (nm) (mmol/g) (m2/g) (cm3/g) MCM-41 1020 0.97 2.33 0.22 5 wt.% Cu/MCM-41 779 0.88 2.31 0.57 10 wt.% Cu/MCM-41 651 0.72 2.25 0.73 20 wt.% Cu/MCM-41 509 0.61 2.17 0.66 30 wt.% Cu/MCM-41 384 0.54 2.01 0.24 5 wt.% Cu/MCM-41-CD 783 0.79 2.33 0.58 10 wt.% Cu/MCM-41-CD 660 0.67 2.33 0.73 20 wt.% Cu/MCM-41-CD 500 0.55 2.24 0.65 30 wt.% Cu/MCM-41-CD 399 0.49 2.15 KIT-6 874 1.12 5.34 0.20 5 wt.% Cu/KIT-6 571 0.89 5.33 0.48 10 wt.% Cu/KIT-6 466 0.57 5.20 0.61 20 wt.% Cu/KIT-6 318 0.39 5.09 0.58 30 wt.% Cu/KIT-6 266 0.30 5.08 0.20 5 wt.% Cu/KIT-6-CD 602 0.85 5.30 0.48 10 wt.% Cu/KIT-6-CD 478 0.55 5.25 0.64 20 wt.% Cu/KIT-6-CD 330 0.31 5.20 0.57 30 wt.% Cu/KIT-6-CD 279 0.26 5.16

CuO crystallite diameter (nm) 6.8 12.2 18.7 28.6 benzene > xylenes > indenes > naphthalenes > others. It is found that about 5% more naphthalene can be obtained by using 20wt.%Cu/MCM-41-CD than 20wt.%Cu/KIT-6-CD due to their different porous structures. The possible mechanism for the catalytic upgrading of bio-oil derived from fast pyrolysis of biomass is proposed in Figure 11. The reactions in the reactor should occur (I) within the solid biomass, (II) over the catalyst and (III) in the gas phase. In the case without catalyst, cellulose is pyrolyzed and converted into gases and anhydrosugars such as levoglucosan (LGA), 1,6-anhydro-β-D-glucofuranose (AGF), levoglucosenone (LGO) and 1,4:3,6-dianhydro-α-D-glucopyranose (DGP) via depolymerization at first and then, the anhydrosugars are further converted into furans via dehydration and re-arrangement reactions


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Figure 11. Overall reaction mechanism to produce aromatic hydrocarbons by catalytic upgrading of bio-oil derived from the fast pyrolysis of biomass. in the presence of catalyst or gas phase.36 Simultaneously, hemicellulose is cleaved at the rings between C2–C5 and the bonds between O–C5 during the fast pyrolysis, transforming into the furfural which can be converted into the furan through dehydration and decarbonylation in the presence of catalyst. Some small molecular oxygenated compounds such as acids, aldehydes and ketones are also formed. For lignin, during fast pyrolysis, its structure is depolymerized as C-C and C-O bonds are broken and transformed into the phenols and phenol alkoxy species.37 Herein, char is formed via re-polymerization and secondary pyrolysis of lignocellulose. Thereafter, the produced intermediate oxygenates diffuse into the catalyst layer, and contact with the surfaces and within the pores of catalyst. As such, they are converted into the aromatic hydrocarbons, CO, CO2 and H2O via a series deoxygenation reaction with catalytic cracking. The C2–C4 alkenes or alkynes are formed to cyclic aliphatic hydrocarbons via combination and 23 ACS Paragon Plus Environment


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then further converted aromatic hydrocarbons via Diels–Alder reaction, aromatization, oligomerization, and cyclization.17 Moreover, the presence of metal catalyst can also serve Lewis acid sites or electron pair acceptors and hydride ions release to promote the transformation of olefins to carbenium ions through intermediate dienes. Even in the absence of these sites, free hydrogen ions may attack carbenium and benzenium ions to produce more light olefins and others through β-scission.38 It is why more aromatic hydrocarbons are generated after using Cu loaded MCM-41 and KIT-6 catalysts. PAHs can be formed in the second series reactions such as further aromatization and polymerization of MAHs with other oxygenates. Coke could be formed on the catalyst by decomposition of gas phase and polycondensation of aromatics, furans and phenols.

Figure 12. Reusability of (A) 20 wt.% Cu/MCM-41, (B) 20 wt.% Cu/MCM-41-CD, (C) 20 wt.% Cu/KIT-6 and (D) 20wt.% Cu/KIT-6-CD for the catalytic upgrading of bio-oil derived from fast pyrolysis of ultrasonic pretreated cedar. 24 ACS Paragon Plus Environment

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Catalyst reusability. The reusability of 20wt.%Cu/MCM-41, 20wt.%Cu/MCM-41-CD, 20wt.%Cu/KIT-6 and 20wt.%Cu/KIT-6-CD are tested at the same condition for 4 cycles. As shown in Figure 12, one can see that a significant reduction of catalytic activity occurs for the spent catalyst without regeneration. The relative total hydrocarbon amount in the bio-oil decreases with the increasing of reusable cycle of spent catalyst. Here, the coke formed on the catalyst causes the blockage of pores and active sites, leading to the deactivation of catalyst. To solve this problem, spent catalysts are regenerated by calcination of them at 650 °C for 30 min under air atmosphere. As expected, no serious reduction on relative hydrocarbon amount is observed for the regenerated catalyst. Interestingly, 20wt.%Cu/MCM41-CD and 20wt.%Cu/KIT-6-CD exhibit much better reusability and higher catalytic activity than 20wt.%Cu/MCM-41 and 20wt.%Cu/KIT-6. As stated above, these should be resulted from the smaller Cu species loaded on the supports with better dispersion. The amounts of coke deposited on the spent catalysts (after 4th reuse) are analyzed by TGA and the results are shown in Table S2. One can see that the coke amount on 20wt.%Cu/KIT-6 is 4.2%, is lower than that on 20wt.%Cu/MCM-41 (6.6%). It is possible that MCM-41 has higher acidity and larger surface area than KIT-6. Moreover, the cokes deposited on 20wt.%Cu/MCM-41-CD and 20wt.%Cu/KIT-6-CD are lower than those on 20wt.%Cu/MCM-41 and 20wt.%Cu/KIT-6. The NH3-TPD profiles of spent catalysts of 20wt.%Cu/MCM-41-CD and 20wt.%Cu/KIT-6-CD before and after regeneration are also shown in Figure 6. For the spent catalyst without regeneration, NH3-TPD peak area with acidity decreases, resulting from the covering of coke on the acid site of catalyst. After regeneration, the acidity of catalyst can be perfectly recovered but the temperature range of NH3 desorption is changed slightly. It is probably due to the effect of some impurities such as alkali and alkaline earth metallic (AAEM) species from the biomass on the spent catalyst.28,39 Figure S3 shows element mappings of spent catalysts (4th reuse). It can be clearly seen that



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AAEM species such as Ca and K exist on the surface of catalyst, which could promote some deoxgenation reactions and improve the quality of bio-oil.40,41 In addition, this may be one reason why the activity is remained for the spent catalysts in this study. On the other hand, the XRD patterns of catalysts after reaction (4th reuse) are shown in Figure 13.

Figure 13. XRD patterns of catalysts after reaction (4th reuse). It can be seen that the new diffraction peaks appear at 43.3, 50.4 and 74.1°,29 corresponding to the Cu metal crystalline phase which should be derived from reduction of CuO as follows: CuO + H2  Cu + H2O

(1)

CuO + CO  Cu + CO2

(2)

where H2 and CO are produced from the fast pyrolysis of cedar. One can see that the intensity of Cu diffraction peaks for spent 20wt.%Cu/MCM-41-CD and 20wt.%Cu/KIT-6-CD are weaker and broader than those of spent 20wt.%Cu/MCM-41 and 20wt.%Cu/KIT-6, also indicating that catalyst prepared with CD assistance has more stability with less accumulation


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and sintering occurrences. All in all, the catalyst structure obtained by using CD assistance during the preparation procedure can improve the anti-coke formation ability and stability of catalyst.

CONCLUSIONS CD-assisted co-impregnation is an effective green way for improving the dispersion of Cu species on MCM-41 and KIT-6. When they are applied for in situ catalytic upgrading of bio-oil derived from fast pyrolysis of biomass, higher catalytic activity is achieved for the promoting of the deoxygenation from the bio-oil when compared with those catalysts prepared by conventional impregnation method. It is found that 20wt.% of Cu loaded MCM41-CD and KIT-6-CD catalysts have the highest catalytic activity, by which the upgraded

bio-oil is rich in monocyclic aromatic hydrocarbons such as benzene, toluene and xylene and the total relative maximum hydrocarbon amount of 73.2% and 86.1% are achieved. Furthermore, after four cycles reuse of the regenerated catalysts, no serious reduction of hydrocarbon yield is found. It indicates that the catalyst structure obtained by using CD assistance during the preparation procedure can improve the anti-coke formation ability and stability of catalyst.

ASSOCIATED CONTENT Supporting Information Available: The proximate, ultimate and ash compositions of cedar wood, the schematic diagram of the experimental setup for in situ catalytic upgrading of biooil, the results of mass balance and gas products derived from ultrasonic pretreated cedar and the existence of AAEM and coke amount on spent catalyst which characterized by SEMEDX and TGA can be found in supporting information.

This material is available free of



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charge via the Internet at http://pubs.acs.org.

ACKNOWLEDGEMENTS This study is supported by Strategic International Collaborative Research Program (SICORP), Japan Science and Technology (JST), Aomori city government, Japan, and the International Joint Research Project of Shanxi Province (No.2015081051and 2015081052). S. Karnjanakom and B. Asep greatly acknowledge the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan for the scholarship.


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KIT-6

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