A Control over Hydrogenation Selectivity of Furfural via Tuning

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A Control over Hydrogenation Selectivity of Furfural via Tuning Exposed Facet of Ni Catalysts Xiaoyu Meng, Yusen Yang, Lifang Chen, Ming Xu, Xin Zhang, and Min Wei ACS Catal., Just Accepted Manuscript • DOI: 10.1021/acscatal.9b00238 • Publication Date (Web): 02 Apr 2019 Downloaded from http://pubs.acs.org on April 2, 2019

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ACS Catalysis

A Control over Hydrogenation Selectivity of Furfural via Tuning Exposed Facet of Ni Catalysts Xiaoyu Meng,†1 Yusen Yang,†1 Lifang Chen,1 Ming Xu,2 Xin Zhang,*1 Min Wei*1

1

State Key Laboratory of Chemical Resource Engineering, Beijing Advanced Innovation

Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, P. R. China 2

College of Chemistry and Molecular Engineering and College of Engineering, BIC-ESAT,

Peking University, Beijing 100871, P. R. China

* Corresponding

authors. Tel: +86-10-64412131; Fax: +86-10-64425385.

E-mail addresses: [email protected] (X. Zhang); [email protected] (M. Wei).

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ABSTRACT: Selective hydrogenation of biomass to value-added products plays a crucial role in the development of renewable energy resources. Herein, two heterogonous Ni catalysts supported on mixed metal oxides (MMO) were prepared via structural topological transformation from hydrotalcites (LDHs) precursors with carbonate or nitrate in interlayer region (denoted as Ni/MMO-CO3 and Ni/MMO-NO3), which were featured by highly-exposed Ni(111) facet as well as multi-facets with abundant steps/vacancies, respectively. Interestingly, the selectivity of furfural hydrogenation can be switched by using these two catalysts: Ni/MMO-NO3 exhibits a high selectivity (97%) to furfural alcohol (FOL) (hydrogenation product of C=O bond); whereas Ni/MMO-CO3 shows an exclusive selectivity (99%) toward tetrahydrofurfuryl alcohol (THFOL, hydrogenation product of both C=O and furan ring). A combination study including HRTEM, EXAFS and in situ CO-IR confirms a large proportion of steps/edges of Ni nanoparticles in Ni/MMO-NO3 catalyst, which suppresses the adsorption of furan ring and only facilitates activated adsorption of C=O group. In contrast, a high exposure of Ni(111) plane in Ni/MMO-CO3 promotes activated adsorption of both furan ring and C=O group, resulting in the production of THFOL. In situ FT-IR measurements and DFT calculations reveal that the adsorption configuration of substrate plays a key role in determining the hydrogenation pathway and selectivity. This work provides a feasible approach for a control over hydrogenation selectivity of biomass molecules by tuning surface microstructure of metal catalysts. KEYWORDS: Ni catalysts, layered double hydroxides, surface structure, selective hydrogenation, furfural

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1. INTRODUCTION Under the circumstances of exhaustion of fossil resources and environmental pollution, renewable resources become highly desirable to meet requirements of energy consumption and chemical production, among which biomass energy and biomass platform molecules have received considerable attention in recent years.14 Furfural is one of the most important biomass-derived chemical owing to its various highly-valued derivatives.58 For instance, furfural alcohol (FOL), half-hydrogenation product of furfural, has been widely used in manufacture of resin, lysine, vitamins and lubricating oils.911 Tetrahydrofurfuryl alcohol (THFOL), deep-hydrogenation product of furfural, is an important green solvent used in agriculture and printing industry.1215 However, the reaction pathway of furfural hydrogenation is rather complicated and how to obtain a high selectively toward a target product remains a conundrum. Although a great number of noble metal-based catalysts have been developed (e.g., control over particle size16 and surface modification17,18), they normally suffer from high cost or laborious preparation process; and a clear fundamental understanding on reaction pathway and parameters governing its selectivity is still lacking. Therefore, rational design and preparation of new catalysts for furfural hydrogenation, so as to achieve a tunable selectivity toward a variety of high value-added downstream products within one catalytic system, still remains a great challenge. In a structure-sensitive reaction such as furfural hydrogenation, surface structure of catalysts imposes a crucial influence on reactant activation, reaction pathway and selectivity.1921 For example, it has been reported that the furan ring of furfural is prone to hydrogenation and decarbonylation at terraces, and carbonyl hydrogenation is likely to occur at 3


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step sites of noble metal catalysts.22 The relative proportion of surface active sites (edges, corners, terraces) is a key factor to control hydrogenation selectivity (FOL vs. THFOL).16 However, an exclusive selectivity toward each single target product, which is highly desirable in practical application, has rarely been reported. Furthermore, fundamental insights on active site-dependent reaction mechanism based on direct experimental studies are rather lacking, which restricts the development of highly-efficient catalysts. Hydrotalcites (LDHs), as a type of 2D anionic clays, consist of positively-charged brucite-like host matrix and exchangeable interlayer guest anions.23,24 One of the most unique properties of LDHs is the so-called in situ structure topological transformation effect: a reduction treatment of LDHs precursors would give rise to supported metal nanoparticles on a mixed metal oxide.25,26 A number of heterogeneous metal catalysts with satisfactory activity and stability have been prepared via the LDHs approach;27,28 and the control over metal type, particle size, and metal-support interactions has been demonstrated.29,30 In addition to the tunability of cations in LDHs host matrix, the interlayer anions would also impose influence on the transformation process and resulting structure of supported metal catalysts, which has unfortunately never been studied. This inspires us to develop a new method for the control over surface fine structure of supported metal catalysts through LDHs precursor with various interlayer anions, for the purpose of largely improving hydrogenation selectivity of furfural. In this work, two NiAl-LDH precursors, with NO3 and CO32 as interlayer anion respectively, were prepared firstly. Followed by a subsequent topological transformation process, we obtained two supported Ni nanocatalysts on MMO substrate (denoted as Ni/MMONO3 and Ni/MMO-CO3), which were used in the selectivity hydrogenation reaction of furfural. 4


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Notably, Ni/MMO-NO3 shows a high selectivity toward FOL (97%) while Ni/MMO-CO3 exhibits selectivity toward THFOL (99%) (Scheme 1). Structural characterizations based on XRD, HRTEM, EXAFS and in situ CO-DRIFTS show multi-facets exposure with abundant steps/edges for Ni/MMO-NO3 sample while a highly-exposed Ni (111) facet for Ni/MMO-CO3 sample. In situ FT-IR measurements and DFT calculations prove that activated adsorption of both C=O group and furan ring occurs on Ni(111) terrace of Ni/MMO-CO3, accounting for the overall hydrogenation of furfural and thus the production of THFOL. In contrast, furan ring has a rather weak interaction with the surface of Ni/MMO-NO3, and only C=O group undergoes linear activated adsorption on Ni surface, which results in a high selectivity to FOL. The surface fine structure of Ni nanoparticles tuned by LDHs precursors with different interlayer anions, imposes an extremely significant influence on adsorption configuration of furfural molecule and the resulting hydrogenation selectivity, which establishes a facile switch between two target products.

Scheme 1. Selective hydrogenation of FAL in the presence of two types of Ni nanoparticles with different surface fine structure. 5


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2. RESULTS AND DISCUSSION 2.1 Structural and morphological studies on supported Ni catalysts Two LDHs precursors (NiAl-LDH-CO3 and NiAl-LDH-NO3) were prepared via in situ growth method by using Al2O3 sphere as Al resource and Ni (NO3)2 as Ni resource, which was developed by our group.31 As shown in Figure 1A1, NiAl-LDH-NO3 displays a series of diffraction peaks at 2 10.0°, 20.0°, 34.3° and 61.3°; while NiAl-LDH-CO3 gives reflections at 2 11.9°, 24.5°, 34.5° and 61.3°, corresponding to (003), (006), (012) and (111) plane of an LDH crystalline phase.21 Their SEM images show a hierarchical flower-like microsphere consisting of NiAl-LDH shell and Al2O3 as a core (Figure 1A2 and A3). Afterwards, a structural transformation process was triggered over these two NiAl-LDHs precursors via calcination treatment in a H2 flow, to obtain two kinds of supported Ni nanoparticle catalysts (represented as Ni/MMO-NO3 and Ni/MMO-CO3). Their XRD patterns (Figure 1B1) display the disappearance of LDH precursors, accompanied with three reflections at 44.5°, 51.8° and 76.4° indexed to a fcc Ni phase and two reflections at 37.2° and 62.8° ascribed to a NiO phase. The particle size was calculated via Scherrer equation based on the average value of these three reflections, i.e., 10.2 nm for Ni/MMO-NO3 and 9.8 nm for Ni/MMO-CO3 sample. SEM images show that the hierarchical morphology is maintained after the reduction treatment (Figure 1B2 and B3), and EDS mapping gives a homogeneous distribution of Ni, Al and O (Figure 1C and D). According to the FT-IR spectra (Figure S1), a sharp band at 1380 cm1 (curve a) and naother one at 1360 cm1 (curve b) are identified as the symmetric stretch of NO3 and CO32 in the samples of NiAl-LDH-NO3 and NiAl-LDH-CO3, respectively. In order to study the effect of interlayer anions on structure transformation process, H2-TPR measurements were 6


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performed over these two NiAl-LDH precursors (Figure S2). NiAl-LDH-CO3 sample shows two reduction peaks at 305 °C and 480 °C; while NiAl-LDH-NO3 displays two higher reduction peaks at 385 °C and 505 °C, indicating the presence of interlayer carbonate accelerates the reduction of LDH precursor. As confirmed by DTG profile (Figure S3), NO3-LDH is more thermally stable than CO3-LDH, which is consistent with previous studies.32,33

Figure 1. XRD patterns of (A1) NiAl-LDH precursors: (a) NiAl-NO3-LDH, (b) NiAl-CO3LDH. (B1) XRD patterns of reduction samples: (a) Ni/MMO-NO3, (b) Ni/MMO-CO3. SEM images of (A2) NiAl-NO3-LDH, (A3) NiAl-CO3-LDH, (B2) Ni/MMO-NO3, (B3) Ni/MMOCO3. EDS element mapping of (C) Ni/MMO-NO3 and (D) Ni/MMO-CO3: Ni (red), O (yellow), Al (green). TEM measurements were carried out to probe the catalyst particle size and surface crystal facet exposure. For these two samples, a high dispersion of Ni nanoparticles is observed within nanoflakes, with a mean particle size of ~10 nm (Figure 2A1 and B1), which is consistent with the results obtained by XRD. Although the particle size distribution is close, their surface 7


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microstructure is quite different (Figure S4). The Ni/MMO-CO3 sample shows lattice fringe of 0.204 nm that is assigned to (111) plane of Ni0. In the case of Ni/MMO-NO3 sample, several crystal planes are observed, including Ni0 (111), Ni0 (010), and Ni0 (211). A multi-facet exposure characteristic of this sample leads to abundant edges and steps between different planes.34 The structural transformation process of hydrotalcites is rather complicated, and several parameters would influence the resulting material (e.g., metal cations, interlayer anions, atmosphere, temperature, etc.). In our previous work,35 we studied the structural transformation of MgAl-CO32-LDH based on DFT calculations, and found that metal cations migrate substantially along the c-axis direction whilst maintain their original arrangement within the (001) facet. The decomposition and release of interlayer anions could impose influence on the nucleation and growth of Ni nanoparticles in a reductive atmosphere. This deserves an in-depth investigation and further study is under investigation in our lab. In addition, the specific surface area values from a BET measurement (Table S1) of these two samples are close: 223.04 m2 g1 for Ni/MMO-NO3 and 243.97 m2 g1 for Ni/MMO-CO3. However, two kinds of pore diameter distributions of Ni/MMO-NO3 are found (2.5 nm and 10 nm); while only one pore size of 4.7 nm is present in Ni/MMO-CO3 (Figure S5).

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Figure 2. TEM and corresponding HRTEM lattice fringe images of (A) Ni/MMO-NO3 and (B) Ni/MMO-CO3. Insets in A1 and B1: size distribution for these two samples. Optimal exposed surfaces of Ni nanoparticles are displayed in (A4) and (B4), respectively. In situ EXAFS spectroscopy was applied to explore fine structure of Ni species in these two samples. As shown in Figure 3A, the normalized Ni K-edge XANES spectra of Ni/MMONO3 and Ni/MMO-CO3 display a significant decline in the white line intensity, in comparison with NiO reference; and the edge features of metallic Ni are obviously present. This indicates the co-existence of both metallic Ni phase and NiO-like phase, which is a typical structural composition of supported metal nanoparticles from a transformation process of LDHs precursors. In order to study the difference in surface microstructure of these two Ni-based samples and to evaluate relative contribution of each Ni species, we carried out linear combination fitting of XANES by using Ni foil (Ni0) and NiO (Ni2+) as reference samples. It is found that metallic Ni0 is dominant in these two samples (78.2% for Ni/MMO-NO3 and 84.0% for Ni/MMO-CO3, respectively). Moreover, the Ni/MMO-NO3 sample gives a NiNi coordination number of 6.2±0.2, much lower than that of Ni/MMO-CO3 (7.8±0.1). This indicates a higher level of unsaturation of NiNi coordination for the former sample ascribed to its multi-facet exposure, in accordance with the results of HRTEM. In addition, according to the curve-fitting data (Table S2), the coordination numbers of Ni–O are 3.1(±0.2) and 2.6(±0.2) for Ni/MMO-NO3 and Ni/MMO-CO3, respectively. CO diffuse reflectance infrared Fourier transform (CO-DRIFT) technique was employed to further explore the electronic structure of surface Ni species. Typically, the characteristic adsorption peaks of CO include liner (20402080 cm1), bridge (~1980 cm1) and hollow adsorption (18501940 cm1);36 and it is reported that CO molecule undergoes liner adsorption 9


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on edge sites while bridge and hollow adsorption normally occur on terrace sites.18 As it shown in Figure 3C, the sample of Ni/MMO-NO3 displays one strong peak at 2051cm1, which is ascribed to the liner CO adsorption. In contrast, Ni/MMO-CO3 shows a rather weak liner adsorption (2060 cm1) and strong bridge adsorption (1950 cm1) and hollow adsorption (1875 cm1). This is ascribed to the variation of surface microstructure of Ni species. Ni/MMO-NO3 sample provides a high exposure of edge/step sites with low NiNi coordination, accounting for the strong liner adsorption of CO. In contrast, on the surface of Ni/MMO-CO3 with terrace Ni sites, liner adsorption is largely depressed whilst bridge and hollow adsorption are predominant. In addition, the liner adsorption band exhibits a significant red-shift from Ni/MMO-NO3 (2060 cm1) to Ni/MMO-CO3 (2051 cm1), which is related to the increased electron feedback from Ni (d orbital) to adsorbed CO (antibonding orbital π*) in the former sample, consistent with the results of XAFS. The different surface microstructure of Ni species would determine the adsorption mode of substrate and hydrogenation pathway/selectivity, which will be further discussed in next section.

Figure 3. (A) Normalized XANES spectra at Ni K-edge for Ni/MMO-NO3, Ni/MMO-CO3, NiO reference and Ni foil, respectively. (B) In situ Fourier-transform EXAFS spectra at Ni Kedge for Ni/MMO-NO3, Ni/MMO-CO3, NiO reference and Ni foil, respectively. (C) In situ Fourier-transformed infrared spectra of CO adsorption on Ni/MMO-NO3 and Ni/MMO-CO3. 10


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2.2 Selective hydrogenation reaction of furfural on Ni/MMO-NO3 and Ni/MMO-CO3 Catalytic performances of as-prepared catalysts were evaluated in selective hydrogenation of furfural (FAL), and the results were illustrated in Figure 4. Reaction conversion of FAL over these two samples is close 100% at 3 h, indicating a similar catalytic activity. However, the selectivity toward final product shows a significant switching between furfural alcohol (FOL) and tetrahydrofurfuryl alcohol (THFOL). In the presence of Ni/MMO-NO3 catalyst (Figure 4A), a selectivity of 97% toward FOL is obtained at 3 h, which almost keeps unchanged within 6 h. This indicates that the further hydrogenation of furan ring in FOL is effectively suppressed on the surface of Ni/MMO-NO3, resulting in a high selectivity toward FOL. In contrast, on the surface of Ni/MMO-CO3 (Figure 4B), the main product is FOL in the beginning of the reaction (02 h), whose selectivity decreases gradually from 97% (at 0.5 h) to 1.0% (at 3 h). Simultaneously, the selectivity of THFOL shows an opposite trend: it gradually increases from 3% (at 0.5 h) to 99% (at 3 h) and then keeps 100% within 46 h. The results above confirm the further hydrogenation of furan ring in FOL occurs on the surface of Ni/MMO-CO3 catalyst, exhibiting a continuous hydrogenation reaction process. It’s quite interesting that an exclusive selectivity toward two different hydrogenation products can be switched facilely via tuning surface microstructure of catalysts, which holds significant promise toward selective hydrogenation in industrial manufacturing. A linear relationship between ln(1  C) and reaction time is obtained over Ni/MMO-NO3 or Ni/MMO-CO3 toward two different products (Figure S6), indicating a first-order reaction. As shown in Table S3, the product formation rate constant of FOL on Ni/MMO-CO3 sample (0.42 h−1) is close to that on Ni/MMO-NO3 (0.53 h−1). However, the formation rate constant of THFOL on Ni/MMO-CO3 sample (0.54 h−1) is 11


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much larger than that on Ni/MMO-NO3 (0.06 h−1). The results indicate that the Ni/MMO-CO3 catalyst is quite active for both FOL formation and furan ring hydrogenation; whilst the Ni/MMO-NO3 catalyst is only active toward the formation of FOL. Moreover, a linear relationship between ln(1  C) and reaction time is obtained over Ni/MMO-NO3 and Ni/MMO-CO3 samples toward FOL hydrogenation (Figure S7), with rate constants of 0.03 and 0.58 h−1, respectively (Table S4), indicating an obvious suppression of this reaction on the surface of Ni/MMO-NO3. In addition, Table S5 shows that the calcined metal mixed oxides derived from two different precursors (without reduction) do not give significant contribution toward this catalytic reaction. As shown in Table S6 (Entries 1 and 2), without the participation of hydrogen molecules (isopropanol as solvent), the reactivity declines sharply (a conversion below 5%). In another case, a substitution of isopropanol with 1,4-dioxane leads to somewhat decrease in catalytic activity and selectivity (Entries 3 and 4). The results above indicate that hydrogen is necessary to provide hydrogen source; and a polar solvent (isopropanol) is better than a non-polar solvent (1,4-dioxane), which is possibly related to the activation of carbonyl group in FAL. In order to investigate the stability of catalysts, recycling experiments of these two catalysts were performed under identical reaction conditions (110 C, 3 MPa, 3 h). As shown in Figure 4, both conversion and seletivitity show a slight decrease and maintain at a high level after 5-time recycles. For the catalyst of Ni/MMO-NO3 (Figure 4C), FAL conversion reamains 95% and FOL selectivity keeps 95% at the 5th test; while for Ni/MMO-CO3 (Figure 4D), FAL conversion of 96% and THFOL selectivity of 97% are obtained at the 5th evalution.

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Figure 4. Catalytic performance for hydrogenation reaction of furfural: conversion and selectivity in the presence of (A) Ni/MMO-NO3 and (B) Ni/MMO-CO3. Reusability tests on (C) Ni/MMO-NO3 and (D) Ni/MMO-CO3 for a 5-time recycles. Reaction conditions: FAL (0.5 mL), catalyst (0.1 g), iso-PrOH (30 mL), temperature (110 °C), H2 pressure (3 MPa). 2.3. Investigations on structure-property correlation of Ni/MMO catalysts In situ FT-IR measurements were carried out to study FAL adsorption on the surface of Ni/MMO-NO3 and Ni/MMO-CO3 samples. As shown in Figure 5A, for the gas phase FAL (curve a), a strong band at 1673 cm1 assigned to ν(C=O) is found.37 An obvious red-shift of ν(C=O) is observed for the adsorbed FAL on catalyst surface: it moves to 1659 cm1 on Ni/MMO-CO3 and 1653 cm1 on Ni/MMO-NO3. This red-shift indicates a pronounced activation adsorption of C=O group, with increased d-π* electron feedback from Ni to adsorbed C=O group, which is more significant on Ni/MMO-NO3 sample with lowly-coordinated Ni (edges/steps). Moreover, two bands at 1578 cm1 and 1474 cm1 are observed for the gas phase 13


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FAL, which are attributed to the aromatic ring breath and ν(C=C).37 It has been reported that chemical adsorption of furan ring on catalyst surface would give rise to disappearance of aromatic ring breath and ν(C=C);38 whereas a free, unconstrained state of furan ring without adsorption produces corresponding IR signals. As for Ni/MMO-CO3, both furan ring breath and ν(C=C) are absent, indicating a strong chemical adsorption of furan ring on catalyst surface. In contrast, these two bands can be observed over Ni/MMO-NO3, implying no adsorption or physical adsorption of furan ring. The results above verify that FAL molecule experiences activation adsorption of both C=O bond and furan ring on Ni/MMO-CO3; whilst only activation adsorption of C=O group occurs on Ni/MMO-NO3, which will be further discussed in the following DFT section. In situ FT-IR spectroscopy was performed to study the hydrogenation reaction of FAL as well as to probe the formation of intermediates/products, by flushing H2 into the reactor at 110 °C (the reaction temperature). A comparative study was implemented between these two catalysts, and detailed knowledge on catalytic reaction pathway can be acquired based on the accumulation and decline of various surface species. Figure 5B and 5C display in situ FT-IR spectra of reaction process of FAL hydrogenation on Ni/MMO-NO3 and Ni/MMO-CO3, respectively, with purging H2 at time point 0 s, 30 s, 90 s, 180 s. For Ni/MMO-NO3 sample (Figure 5B1 and B2), the band at 1653 cm1 (characteristic band of C=O) declines gradually along with continuous flushing of H2, accompanied with observation of a new band at 1105 cm1 (alcohol C−O group),39 which illustrates the hydrogenation process of C=O bond. Moreover, the characteristic signals of ring breath (1578 cm1) and C=C (1474 cm1) do not display marked variation from t=0 to t=90 s, excluding hydrogenation progress on furan ring. 14


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At t=180 s, the FT-IR signals completely disappear, indicating desorption of FOL molecule from catalyst surface. In contrast, in the case of Ni/MMO-CO3 system (Figure 5C1 and C2), FT-IR band of C=O (1659 cm1) decreases progressively companied with the rise of CO signal (1105 cm1) upon H2 flushing. Since furan ring experiences chemical adsorption on Ni/MMOCO3 surface, no characteristic signals can be found during this process. The free FAL molecule in gas phase gives bond lengths of 1.229 Å and 1.381 Å for C=O and C=C, respectively (Table S7, entry 1). They increase to 1.309 Å (C=O) and 1.456 Å (C=C) on the surface of Ni(111) (Table S7, entry 2), due to the adsorption of both C=O and C=C bond, which is consistent with the FT-IR spectra of FAL adsorption on Ni/MMO-CO3. In contrast, on the surface of Ni(211), the bond length of C=O is prolonged to 1.323 Å whilst C=C bond (1.394 Å) do not show obvious change relative to its free state (Table S7, entry 3). This indicates only C=O (not C=C) undergoes activation adsorption on the surface of Ni/MMO-NO3, in agreement with the experimental studies.

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Figure 5. (A1) In situ FT-IR spectra of (a) gas phase of FAL by using -Al2O3 as a blank sample, adsorbed FAL on (b) Ni/MMO-NO3 and (c) Ni/MMO-CO3, respectively, recorded after flowing FAL for 30 min at 25 °C and subsequently He flushing for 30 min. (A2) Molecular structure of furfural. In situ FT-IR spectra for hydrogenation process of FAL on (B) Ni/MMO-NO3 and (C) Ni/MMO-CO3 via flowing H2 as a reaction gas. From curve a to d in each panel: 0 s, 30 s, 90 s, 180 s, respectively. As mentioned above, FAL hydrogenation is a continuous reaction and FOL is an 16


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intermediate of hydrogenation process. If the intermediate FOL is easy to detach from the catalyst surface, over-hydrogenation is less likely to occur. So in situ IR measurements of FOL desorption were carried out via continuous flushing FOL into the reactor for 30 min for a saturated adsorption followed by He purging (30 min) to remove gaseous and physicallyadsorbed FOL. On the surface of Ni/MMO-NO3 (Figure 6A), the two bands ascribed to (CO) and (CH2) at 1105 cm1 and 1030 cm1, respectively, were chosen for study. The peak intensity drops sharply upon increasing temperature from 20 to 80 °C, and vanishes completely at 110 °C. However, in the case of Ni/MMO-CO3 (Figure 6B), the peak intensity shows a relatively slow decline and remains a rather strong signal of FOL at 110 °C. In addition, the normalized desorption rate curves (Figure S8) verify a much faster detachment of FOL from Ni/MMO-NO3 than that from Ni/MMO-CO3, consistent with their catalytic behavior. In order to further confirm the different impact of these two catalysts on furan ring hydrogenation, we evaluated the performance of FOL as a reaction substrate, which is a traditional way to obtain THFOL (Figure S9).40 As expected, almost no conversion of FOL is found on Ni/MMO-NO3 whilst FOL complete converts to THFOL on the surface of Ni/MMO-CO3. In addition, in situ FT-IR spectra of adsorbed FOL and THFOL over Ni/MMO-NO3 and Ni/MMO-CO3 samples were performed. As shown in Figure S10A, the bands at 1560 cm1 and 1503 cm1 are ascribed to the ring breath and C=C stretching of FOL, respectively, which show the same trend compared with Figure 5. On the sample of Ni/MMO-NO3, the two bands at 1560 cm1 and 1503 cm1 almost have no change compared with the gas phase of FOL, but they disappear on the sample of Ni/MMO-CO3. The results further confirm that the furan ring tends to adsorb on the surface of Ni/MMO-CO3 rather than on Ni/MMO-NO3. Figure S10B shows FT-IR spectra 17


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of adsorbed THFOL on these two catalysts. After flushing He for 30 min, only a small amount of residue was detected on the catalyst surface, indicating a weak adsorption of THFOL.

Figure 6. In situ FT-IR spectra of FOL desorption from (A) Ni/MMO-NO3 and (B) Ni/MMOCO3 within a temperature range 20110 °C. As the most important intermediate, the direction of FOL (hydrogenation vs. desorption) plays an essential role in determining catalytic selectivity of Ni/MMO-NO3 and Ni/MMO-CO3. Therefore, DFT calculations were carried out to understand the relationship between adsorption configuration of FOL, hydrogenation pathway and reaction selectivity on these two samples. According to the results of XRD and HRTEM, optimal exposed surfaces, Ni(211) described as Ni [3(111) × (010)] for Ni/MMO-NO3 and Ni(111) for Ni/MMO-CO3 which can represent the surface characteristic, are selected for subsequent calculations (Figure S11). Based on the in situ FT-IR observations, in the case of Ni/MMO-NO3 system, the most reasonable adsorption state (Table S8) of FOL is that the O1 is chemically adsorbed on the step site of Ni(211), with the NiO1 bond length of 2.065 Å. The C3=C4 in furan ring is physically adsorbed on terrace site with a distance between Ni and C3(C4) of 3.557 Å (3.322 Å), implying a rather weak interaction between furan ring and catalyst surface (Figure S12: Configuration e). This is in 18


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agreement with the observation of ring breath peak at 1578 cm1, in in situ FT-IR measurements (Figure 5), which provides a reliable model for the study of follow-up reaction pathway. In the presence of Ni/MMO-CO3 sample however, the most favorable adsorption mode of FOL on Ni(111) is that hydroxyl oxygen is adsorbed on top site of Ni and furan ring plane is located parallel to the surface across two three-fold hollow sites (Figure S13), in which ring plane is effectively activated. According to the adsorption configurations discussed above, the hydrogenation process of FOL on Ni(211) (Table S9) and Ni(111) (Table S10)surface were investigated, and the free energies profiles (eV) were depicted in Figure 6A. For Ni(211) surface (Figure 6A, right), desorption free energy of adsorbed FOL to the gas phase is 1.18 eV, and the unique adsorption mode of FOL inhibits hydrogenation of C=C in furan ring, resulting in a facile desorption of FOL from the surface of Ni/MMO-NO3 catalyst (Figure S14). In contrast, on Ni(111) surface, FOL molecule gives a desorption free energy of 1.72 eV while a hydrogenation energy barrier of 0.88 eV, giving rise to further hydrogenation of furan ring to produce THFOL on the surface of Ni/MMO-CO3 (Figure 6A, left). Therefore, an effective activation as well as desorption free energy vs. hydrogenation energy barrier are two key factors which determine hydrogenation selectivity (Figure S15). To further reveal electron effect derived from Ni/MMO-NO3 and Ni/MMO-CO3 sample, the projected density of states were calculated and depicted in Figure 6B. The d band center position of Ni-3d is located at 1.65 eV in Ni(111) and at 1.21 eV in Ni(211), accounting for the high catalytic activity for these two sample. Furthermore, geometric effect (coordination number of surface reactive atoms) also imposes a crucial influence on catalytic performance of 19


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Ni/MMO-NO3 and Ni/MMO-CO3 samples. On the one hand, the interaction between O1 and Ni in a low coordination (step site, Ni (211), bond length: 2.065 Å) is stronger than that in a high coordination (terrace, Ni(111), bond length: 2.290 Å) (Figure 7C). On the other hand, FOL molecule adsorbed on the step sites prefers to desorption than on the terrace site (desorption energy: 1.18 eV vs. 1.72 eV), due to the strong interaction between C2, C3 and O2 in furan ring and surface terrace site. Therefore, the existence of specific active sites on catalyst surface would induce unique adsorption configuration of substrate, which imposes an essential impact on hydrogenation pathway and product selectivity.

Figure 7. (A) Free energies profiles (unit: eV) for FOL hydrogenation on Ni(111) and Ni(211) surface. Numbers in the parentheses represent free energy barriers of elementary step. (FOLH)* stands for FOL hydrogenated by one hydrogen atom. (B) Projected density of states of Ni-3d in Ni(111) and Ni(211). Corresponding blue and red dash lines represent the position of d band 20


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center. (C) Bond length of NiO1 or adsorption energy as a function of coordination number (CN) of Ni. The solid triangle denotes adsorption energy and the hollow star represents bond length.

3. CONCLUSION Two types of Ni catalysts were synthesized on the basis of LDHs precursors with different interlayer anions (nitrate or carbonate), which showed completely different catalytic selectivity toward furfural hydrogenation. The resulting Ni/MMO-NO3 exhibits a high selectivity for FOL (97%) while Ni/MMO-CO3 is exclusively selective toward THFOL (99%). A selectivity switching can be facilely achieved via tuning interlayer anion of LDHs precursors, which is highly desirable for industrial applications. The Ni/MMO-NO3 catalyst is characterized by a low coordination of surface Ni with abundant step sites, confirmed by HRTEM, XAFS, and CO-IR, which accelerates the linear activation adsorption of C=O group in furfural and thus the production of FOL. In contrast, terrace sites are predominant on Ni/MMO-CO3 surface, which are conducive to the activation adsorption of both C=O group and C=C bond in furan ring (flat adsorption configuration). This leads to the full hydrogenation of furfural to produce THFOL. Both experimental studies (catalytic evaluations, in situ FT-IR spectroscopy) and PDT calculations reveals the correlation between adsorption configuration of substrate and hydrogenation pathway/selectivity. This work provides a successful paradigm for a facile control over hydrogenation reaction selectivity via tuning surface microstructure of heterogeneous catalysts.

4. EXPERIMENTAL SECTION 4.1 Materials Chemical reagents, including Ni(NO3)2·6H2O, Al(NO3)3·9H2O, NH4NO3·xH2O, C4H4Na2O6, NH3·H2O, 21


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Na2CO3 and urea were bought from Sigma Aldrich and used without further purification. Deionized water was used in all experimental processes. 4.2 Preparation of Ni/MMO-NO3 and Ni/MMO-CO3 Synthesis of Al2O3 microspheres: urea (6.72 g), Al(NO3)3·9H2O (18.64 g), C4H4Na2O6 (0.64 g) were dissolved in water (280 mL), which was then sealed in a Teflon lined autoclave at 150 °C for 3 h. The resulting precipitate was separated, washed thoroughly and dried at 60 °C, followed by a calcination treatment at 500 °C for 4 h. Synthesis of NiAl-NO3-LDH and NiAl-CO3-LDH: NiAl-NO3-LDH was prepared by an in situ growth method. Al2O3 microspheres (1.00 g) were dispersed in 1000 mL of deionized and decarbonated water (purged with N2 to remove carbonate); Ni(NO3)2·6H2O (34.89 g) and NH4NO3·xH2O (57.60 g) were added into the solution and NH3·H2O was used to keep the pH value at ~6.5. The solution was stirred in a flask at 90 C for 48 h to obtain NiAl-NO3-LDH. NiAl-CO3-LDH sample was synthesized by using anion-exchange method as follows: 0.2 g of NiAl-NO3-LDH was dispersed into a Na2CO3 solution (0.1 g, 100 mL) and was stirred in a flask at 25 C for 6 h, followed by centrifugation and dried at 60 °C. Synthesis of Ni/MMO-NO3 and Ni/MMO-CO3: the precursors (NiAl-NO3-LDH or NiAl-CO3-LDH) were calcined in a reduction atmosphere (H2/N2=1/9, v/v) at 450 C for 4 h, at a heating rate of 5 C min1, to obtain Ni/MMO-NO3 or Ni/MMO-CO3 sample. Then these two samples were stored in N2 for subsequent catalytic evaluation. 4.3 Catalytic evaluations Furfural (0.5 mL), iso-PrOH (30 mL) and 0.10 g of catalyst were loaded into a stainless-steel reactor. Air inside was displaced by pure H2 (3.0 Mpa) three times, followed by flowing pure H2 with a pressure of 3 MPa. The reactor temperature was raised to 110 C to trigger the catalytic reaction. Products analysis was 22


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performed on a GC (Shimadzu GC-2014C) equipped with a flame ionization detector, by using n-butanol as an internal standard. The conversion of furfural was calculated by the equation: 1―

Con. =

𝐴𝑆 × 𝑀𝑆𝑖 𝐴𝑆𝑖

𝑀𝑆

×100%

(1)

where AS and ASi denote peak area of furfural and internal standard; MS and MSi are the number of moles of initial furfural and internal standard, respectively. The selectivity of FOL or THFOL was calculated by formulas: 𝐴𝑆𝑒 × 𝑀𝑆𝑖

Sel. =

𝐴𝑆𝑖

𝑀𝑆

×100%

(2)

where ASe and ASi denote peak area of final product and internal standard, respectively. 4.4 Computational details Spin-polarized periodic DFT calculations were performed using the Vienna ab initio simulation package (VASP 5.4.1).41,42 The projector augmented wave (PAW)43,44 method and the generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhoff (PBE) functional45 were used to solve the KohnSham equations. The Grimme’s DFT-D346 was added so as to study the impact of van der Waals interaction on reaction energies. The fcc Ni bulk phase was optimized as 3.478 Å of lattice constant, for the construction of slab models of terrace Ni(111) and step Ni(211). The Ni(211) can be delegated as Ni [3(111) × (100)] step surface. The Ni(111) surface and Ni(211) surface were modeled with a four-layer-slab in a p(4 × 4) and p(1 × 2) surface unit cell and a vacuum space of 16 Å to avoid interactions between slabs, in which the bottom two layers were fixed whilst the top two layers were fully relaxed. DFT calculations were carried out with a cutoff energy of 400 eV and 4 × 4 × 1 k-point Monkhorst-Pack grid. The convergence criteria for the electronic self-consistent iteration and force were respectively set to 104 eV and 0.05 eV/Å. The climbing 23


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image nudged elastic band (CI-NEB) method47 was used to find transition states. The adsorption energies (Eads) of reactants/products were obtained based on the equation Eads= Etotal – (Esurf + Eadsorbate)

(3)

where Etotal is the system energy after adsorption; Esurf is the energy of clean surface, and Eadsorbate denotes the energy of free adsorbate (gas phase). The reaction barrier Ea was calculated by: Ea = E(TS) - E(IS)

(4)

where E(IS), E(FS), and E(TS) are the energies of initial state (IS), final state (FS), and transition state (TS), respectively. Vibrational frequencies were used to calculate zero-point energies (ZPE) and free energies (G) by G = EDFT + ZPE – TS

(5)

where EDFT represents the total energy and TS is the entropy term. S is calculated based on the following formula

S

v m

  hcv   hcv  R   hcv  ln 1  e  1  e





 

(6)

Where β is the Boltzman constant; h is the Planck constant; c is the light speed, and ν is the wave number. 4.5 Characterizations X-ray diffraction (XRD) patterns were collected on a Rigaku XRD-6000 diffractometer by using Cu Ka radiation (λ = 0.15418 nm, 40 kV, 40 mA). A Zeiss Supra 55 scanning electron microscope (SEM) and a JEOL JEM-2010 high-resolution transmission electron microscope were employed to acquire morphological and structural information. Hydrogen temperature programmed reduction (H2-TPR) measurements were carried out on a Micromeritics Chemi-Sorb 2720 equipped with a thermal conductivity detector (TCD). Typically, the sample (100 mg) was sealed into a quartz tube reactor, followed by flowing a mixed gas of H2 24


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and Ar (1:9, v/v) at a heating rate of 5 C min1 from 50 C to 800 C. XAFS measurements were carried out at beam line 1W1B of the Beijing Synchrotron Radiation Facility (BSRF), Institute of High Energy Physics (IHEP), Chinese Academy of Sciences (CAS). In situ FT-IR measurements of CO adsorption and furfural adsorption were performed by using a Bruker infrared spectrometer in an in situ transmission cell on a VERTEX 70 spectrometer equipped with KBr window. In a typical procedure, the sample installed in the cell was treated by a mixture gas of H2 and N2 (H2/N2=1/9, v/v) at 450 C for 1 h and then cooled down to room temperature, followed by purging He for 1 h (flow rate: 100 cm3 min−1). Subsequently, CO (or furfural) was introduced into the cell for 30 min, followed by flowing helium (rate: 100 cm3 min−1) for another 30 min to remove physically-adsorbed species. Then FT-IR spectra were recorded at 25C at 0 s, 30 s, 90 s, 180 s, respectively.

AUTHOR INFORMATION Corresponding Authors [email protected] (X. Zhang); [email protected] (M. Wei) Author contributions †(X.

Meng, Y. Yang) These authors contributed equally to this work.

ORCID 0000-0003-3559-2096 (X. Zhang); 0000-0001-5257-790X (M. Wei) Notes The authors declare no competing financial interest.

ASSOCIATED CONTENT Supporting Information. Figures S1−S15 and Tables S1−S10. This material is available free of charge via the Internet at http://pubs.acs.org. Acknowledgment 25


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This work was supported by the National Natural Science Foundation of China (NSFC: 21871021 and 21521005), the National Key Research and Development Program (Grant No. 2017YFA0206804), and the Fundamental Research Funds for the Central Universities (buctylkxj01 and XK1802-6).

REFERENCES (1) Liu, W. J.; Li, W. W.; Jiang, H.; Yu, H. Q. Fates of Chemical Elements in Biomass During Its Pyrolysis. Chem. Rev. 2017, 117, 6367−6398. (2) Besson, M.; Gallezot, P.; Pinel, C. Conversion of Biomass into Chemicals over Metal Catalysts. Chem. Rev. 2014, 114, 1827−1870. (3) Sun, D.; Sato, S.; Ueda, W.; Primo, A.; Garcia, H.; Corma, A. Production of C4 and C5 Alcohols from Biomass-Derived Materials. Green. Chem. 2016, 18, 2579−2597. (4) Nakagawa, Y.; Tamura, M.; Tomishige, K. Catalytic Reduction of Biomass-Derived Furanic Compounds with Hydrogen. ACS Catal. 2013, 3, 2655−2668. (5) Zhang, X.; Wilson, K.; Lee, A. F. Heterogeneously Catalyzed Hydrothermal Processing of C5−C6 Sugars. Chem. Rev. 2016, 116, 12328−12368. (6) Zhang, Z.; Song, J.; Han, B. Catalytic Transformation of Lignocellulose into Chemicals and Fuel Products in Ionic Liquids. Chem. Rev. 2017, 117, 6834−6880. (7) Li, X.; Jia, P.; Wang, T. Furfural: A Promising Platform Compound for Sustainable Production of C4 and C5 Chemicals. ACS Catal. 2016, 6, 7621−7640. (8) Deng, Y.; Gao, R.; Lin, L.; Liu, T.; Wen, X.; Wang, S.; Ma, D. Solvent Tunes the Selectivity of Hydrogenation Reaction over α‑MoC Catalyst. J. Am. Chem. Soc. 2018, 140, 14481−14489. (9) Mandalika, A.; Li, Q.; Sato, T. K.; Runge, T. Integrated Biorefinery Model Based on Production of Furans Using Open-Ended High Yield Processes. Green. Chem. 2014, 16, 2480−2489. (10) Sharma, R. V.; Das, U.; Sammynaiken, R.; Dalai, A. K. Liquid Phase Chemo-Selective Catalytic Hydrogenation of Furfural to Furfuryl Alcohol. Appl. Catal., A 2013, 454, 127−136. (11) Guo, H.; Zhang, H.; Zhang, L.; Wang, C.; Peng, F.; Huang, Q.; Xiong, L.; Huang, C.; Ouyang, X.; Chen, X.; Qiu, X. Selective Hydrogenation of Furfural to Furfuryl Alcohol over Acid-Activated AttapulgiteSupported NiCoB Amorphous Alloy Catalyst. Ind. Eng. Chem. Res. 2018, 57, 498−511. (12) Koso, S.; Furikado, I.; Shimao, A.; Miyazawa, T.; Kunimori, K.; Tomishige, K. Chemoselective 26


Page 26 of 39

Page 27 of 39 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

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Hydrogenolysis of Tetrahydrofurfuryl Alcohol to 1,5-Pentanediol. Chem. Commun. 2009, 51, 2035−2037. (13) Koso, S.; Ueda, N.; Shinmi, Y.; Okumura, K.; Tomishige, K. Promoting Effect of Mo on the Hydrogenolysis of Tetrahydrofurfuryl Alcohol to 1,5-Pentanediol over Rh/SiO2. J. Catal. 2009, 267, 89−92. (14) Wang, H.; Li, X.; Lan, X.; Wang, T. Supported Ultrafine NiCo Bimetallic Alloy Nanoparticles Derived from Bimetal–Organic Frameworks: A Highly Active Catalyst for Furfuryl Alcohol Hydrogenation. ACS Catal. 2018, 8, 2121−2128. (15) Seemala, B.; Cai, C. M.; Wyman, C. E.; Christopher, P. Support Induced Control of Surface Composition in Cu–Ni/TiO2 Catalysts Enables High Yield Co-Conversion of HMF and Furfural to Methylated Furans. ACS Catal. 2017, 7, 4070−4082. (16) Rogers, S. M.; Catlow, C. R. A.; Chan-Thaw, C. E.; Chutia, A.; Jian, N.; Palmer, R. E.; Perdjon, M.; Thetford, A.; Dimitratos, N.; Villa, A. Tandem Site and Size Controlled Pd Nanoparticles for the Directed Hydrogenation of Furfural. ACS Catal. 2017, 7, 2266−2274. (17) Jeong, H.; Kim, C.; Yang, S.; Lee, H. Selective Hydrogenation of Furanic Aldehydes Using Ni Nanoparticle Catalysts Capped with Organic Molecules. J. Catal. 2016, 344, 609−615. (18) Pang, S. H.; Schoenbaum, C. A.; Schwartz, D. K.; Medlin, J. W. Effects of Thiol Modifiers on the Kinetics of Furfural Hydrogenation over Pd Catalysts. ACS Catal. 2014, 4, 3123−3131. (19) Bhogeswararao, S.; Srinivas, D. Catalytic Conversion of Furfural to Industrial Chemicals over Supported Pt and Pd Catalysts. J. Catal. 2015, 327, 65−77. (20) Serrano-Ruiz, J. C.; López-Cudero, A.; Solla-Gullón, J.; Sepúlveda-Escribano, A.; Aldaz, A.; Rodríguez-Reinoso, F. Hydrogenation of Α , Β Unsaturated Aldehydes over Polycrystalline, (111) and (100) Preferentially Oriented Pt Nanoparticles Supported on Carbon. J. Catal. 2008, 253, 159−166. (21) Wang, C.; Wang, L.; Zhang, J.; Wang, H.; Lewis, J. P.; Xiao, F. S. Product Selectivity Controlled by Zeolite Crystals in Biomass Hydrogenation over a Palladium Catalyst. J. Am. Chem. Soc. 2016, 138, 7880−7883. (22) Wang, S.; Vorotnikov, V.; Vlachos, D. G. Coverage-Induced Conformational Effects on Activity and Selectivity: Hydrogenation and Decarbonylation of Furfural on Pd(111). ACS Catal. 2015, 5, 104−112. (23) Kumar, G.; Lien, C. H.; Janik, M. J.; Medlin, J. W. Catalyst Site Selection via Control over NonCovalent Interactions in Self-Assembled Monolayers. ACS Catal. 2016, 6, 5086−5094. (24) Qiang, W.; Dermot, O. H. Recent Advances in the Synthesis and Application of Layered Double Hydroxide (LDH) Nanosheets. Chem. Rev. 2012, 112, 4124−4155. 27


ACS Catalysis 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

(25) Eugenio, C.; Galán-Mascarós, J. R.; Carlos, M. G.; Antonio, R.; Elías, P.; Miguel, C.; Ramón, B. Spontaneous Magnetization in Ni−Al and Ni−Fe Layered Double Hydroxides. Inorg. Chem. 2008, 47, 9103−9110. (26) Fan, Q.; Li, X.; Yang, Z.; Han, J.; Xu, S.; Zhang, F. Double-Confined Nickel Nanocatalyst Derived from Layered Double Hydroxide Precursor: Atomic Scale Insight into Microstructure Evolution. Chem. Mater. 2016, 28, 6296−6304. (27) Meng-Qiang, Z.; Qiang, Z.; Wei, Z.; Jia-Qi, H.; Yinghao, Z.; Dang Sheng, S.; Fei, W. Embedded High Density Metal Nanoparticles with Extraordinary Thermal Stability Derived from Guest-Host Mediated Layered Double Hydroxides. J. Am. Chem. Soc. 2010, 132, 14739−14741. (28) Li, M. J.; Chen, C.; Ayvali, T.; Suo, H.; Zheng, J.; Teixeira, I.; Ye, L.; Zou, H.; O'Hare, D.; Tsang, S. C. E. CO2 Hydrogenation to Methanol over Catalysts Derived from Single Cationic Layer CuZnGa LDH Precursors. ACS Catal. 2018, 8, 4390−4401. (29) Xu, M.; He, S.; Chen, H.; Cui, G.; Zheng, L.; Wang, B.; Wei, M. Tio2–X-Modified Ni Nanocatalyst with Tunable Metal–Support Interaction for Water–Gas Shift Reaction. ACS Catal. 2017, 7, 7600−7609. (30) Fan, G.; Li, F.; Evans, D. G.; Duan, X. Catalytic Applications of Layered Double Hydroxides: Recent Advances and Perspectives. Chem. Soc. Rev. 2015, 45, 7040−7066. (31) He, S.; Li, C.; Chen, H.; Su, D.; Zhang, B.; Cao, X.; Wang, B.; Wei, M.; Evans, D. G.; Duan, X. A Surface Defect-Promoted Ni Nanocatalyst with Simultaneously Enhanced Activity and Stability. Chem. Mater. 2013, 25, 1040−1046. (32) Tichit, D.; Medina, F.; Coq, B.; Dutartre, R.; Activation Under Oxidizing and Reducing Atmospheres of Ni-Containing Layered Double Hydroxides. Appl. Catal. A Gen. 1997. 159, 241258. (33) Wu, X., Du, Y., An, X., Xie, X. Fabrication of NiFe Layered Double Hydroxides Using Urea HydrolysisControl of Interlayer Anion and Investigation on Their Catalytic Performance. Catal. Commun. 2014, 50, 4448. (34) Wang, H.; Xu, K.; Yao, X.; Ye, D.; Pei, Y.; Hu, H.; Qiao, M.; Li, Z. H.; Zhang, X.; Zong, B. Undercoordinated Site-Abundant and Tensile-Strained Nickel for Low-Temperature COx Methanation. ACS Catal. 2018, 8, 1207−1211. (35) Zhang, S.; Dou, Y.; Zhou, J.; Pu, M.; Yan, H.; Wei, M.; Evans, D. G.; Duan, X. DFT-Based Simulation and Experimental Validation of the Topotactic Transformation of MgAl Layered Double Hydroxides. ChemPhysChem. 2016. 17, 27542766. 28


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(36) Layman, K. A.; Bussell, M. E. Infrared Spectroscopic Investigation of CO Adsorption on SilicaSupported Nickel Phosphide Catalysts. J. Phys. Chem. B 2004, 108, 10930−10941. (37) Shi, D.; Vohs, J. M. Deoxygenation of Biomass-Derived Oxygenates: Reaction of Furfural on ZnModified Pt(111). ACS Catal. 2015, 5, 2177−2183. (38) Yu, W.; Xiong, K.; Ji, N.; Porosoff, M. D.; Chen, J. G. Theoretical and Experimental Studies of the Adsorption Geometry and Reaction Pathways of Furfural over FeNi Bimetallic Model Surfaces and Supported Catalysts. J. Catal. 2014, 317, 253−262. (39) Daly, H.; Manyar, H. G.; Morgan, R.; Thompson, J. M.; Delgado, J. J.; Burch, R.; Hardacre, C. Use of Short Time-on-Stream Attenuated Total Internal Reflection Infrared Spectroscopy to Probe Changes in Adsorption Geometry for Determination of Selectivity in the Hydrogenation of Citral. ACS Catal. 2014, 4, 2470−2478. (40) Biradar, N. S.; Hengne, A. M.; Birajdar, S. N.; Niphadkar, P. S.; Joshi, P. N.; Rode, C. V. Single-Pot Formation of THFAL via Catalytic Hydrogenation of FFR over Pd/MFI Catalyst. ACS Sustainable Chem. Eng. 2013, 2, 272−281. (41) Kresse, G.; Furthmüller, J. Efficiency of Ab-Initio Total Energy Calculations for Metals and Semiconductors Using a Plane-Wave Basis Set. Comput. Mater. Sci. 1996, 6, 15−50. (42) Kresse, G.; Furthmüller, J. Efficient Iterative Schemes for Ab Initio Total-Energy Calculations Using A Plane-Wave Basis Set. Phys. Rev. B 1996, 54, 11169−11186. (43) Blöchl, P. E. Projector Augmented-Wave Method. Phys. Rev. B 1994, 50, 17953−17979. (44) Kresse, G.; Joubert, D. From Ultrasoft Pseudopotentials to the Projector Augmented-Wave Method. Phys. Rev. B 1999, 59, 1758−1775. (45) Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865−3868. (46) Grimme, S.; Antony, J.; Ehrlich, S.; Krieg, H. A Consistent and Accurate Ab Initio Parametrization of Density Functional Dispersion Correction (DFT-D) for the 94 Elements H-Pu. J. Chem. Phys. 2010, 132, 154104. (47) Henkelman, G.; Uberuaga, B. P.; Jónsson, H. A Climbing Image Nudged Elastic Band Method for Finding Saddle Points and Minimum Energy Paths. J. Chem. Phys. 2000, 113, 9901−9904.

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ACS Catalysis

Scheme 1. Selective hydrogenation of FAL in the presence of two types of Ni nanoparticles with different surface fine structure. 50x32mm (300 x 300 DPI)


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Figure 1. XRD patterns of (A1) NiAl-LDH precursors: (a) NiAl-NO3-LDH, (b) NiAl-CO3-LDH. (B1) XRD patterns of reduction samples: (a) Ni/MMO-NO3, (b) Ni/MMO-CO3. SEM images of (A2) NiAl-NO3-LDH, (A3) NiAl-CO3-LDH, (B2) Ni/MMO-NO3, (B3) Ni/MMO-CO3. EDS element mapping of (C) Ni/MMO-NO3 and (D) Ni/MMO-CO3: Ni (red), O (yellow), Al (green). 50x43mm (300 x 300 DPI)


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ACS Catalysis

Figure 2. TEM and corresponding HRTEM lattice fringe images of (A) Ni/MMO-NO3 and (B) Ni/MMO-CO3. Insets in A1 and B1: size distribution for these two samples. Optimal exposed surfaces of Ni nanoparticles are displayed in (A4) and (B4), respectively. 50x21mm (300 x 300 DPI)


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Figure 3. (A) Normalized XANES spectra at Ni K-edge for Ni/MMO-NO3, Ni/MMO-CO3, NiO reference and Ni foil, respectively. (B) In situ Fourier-transform EXAFS spectra at Ni K-edge for Ni/MMO-NO3, Ni/MMO-CO3, NiO reference and Ni foil, respectively. (C) In situ Fourier-transformed infrared spectra of CO adsorption on Ni/MMO-NO3 and Ni/MMO-CO3. 50x17mm (300 x 300 DPI)


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ACS Catalysis

Figure 4. Catalytic performance for hydrogenation reaction of furfural: conversion and selectivity in the presence of (A) Ni/MMO-NO3 and (B) Ni/MMO-CO3. Reusability tests on (C) Ni/MMO-NO3 and (D) Ni/MMOCO3 for a 5-time recycles. Reaction conditions: FAL (0.5 mL), catalyst (0.1 g), iso-PrOH (30 mL), temperature (110 °C), H2 pressure (3 MPa). 50x37mm (300 x 300 DPI)


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Figure 5. (A1) In situ FT-IR spectra of (a) gas phase of FAL by using -Al2O3 as a blank sample, adsorbed FAL on (b) Ni/MMO-NO3 and (c) Ni/MMO-CO3, respectively, recorded after flowing FAL for 30 min at 25 °C and subsequently He flushing for 30 min. (A2) Molecular structure of furfural. In situ FT-IR spectra for hydrogenation process of FAL on (B) Ni/MMO-NO3 and (C) Ni/MMO-CO3 via flowing H2 as a reaction gas. From curve a to d in each panel: 0 s, 30 s, 90 s, 180 s, respectively. 50x65mm (300 x 300 DPI)


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ACS Catalysis

Figure 6. In situ FT-IR spectra of FOL desorption from (A) Ni/MMO-NO3 and (B) Ni/MMO-CO3 within a temperature range 20-110 °C. 50x19mm (300 x 300 DPI)


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Figure 7. (A) Free energies profiles (unit: eV) for FOL hydrogenation on Ni(111) and Ni(211) surface. Numbers in the parentheses represent free energy barriers of elementary step. (FOLH)* stands for FOL hydrogenated by one hydrogen atom. (B) Projected density of states of Ni-3d in Ni(111) and Ni(211). Corresponding blue and red dash lines represent the position of d band center. (C) Bond length of Ni-O1 or adsorption energy as a function of coordination number (CN) of Ni. The solid triangle denotes adsorption energy and the hollow star represents bond length. 50x48mm (300 x 300 DPI)


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ACS Catalysis

TOC 50x22mm (300 x 300 DPI)


A Control over Hydrogenation Selectivity of Furfural via Tuning

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