Preparation of a cobalt-nickel catalyst using an inorganic precursor for the Fischer-Tropsch synthesis

Journal Pre-proofs Preparation of a cobalt-nickel catalyst using an inorganic precursor for the fischer-tropsch Synthesis Sania Saheli, Ali Reza Rezvani, Vaclav Eigner PII: DOI: Reference:

S0277-5387(19)30782-X https://doi.org/10.1016/j.poly.2019.114337 POLY 114337

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Please cite this article as: S. Saheli, A.R. Rezvani, V. Eigner, Preparation of a cobalt-nickel catalyst using an inorganic precursor for the fischer-tropsch Synthesis, Polyhedron (2019), doi: https://doi.org/10.1016/j.poly. 2019.114337

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Preparation of a Cobalt-Nickel Catalyst Using an Inorganic Precursor for the FischerTropsch Synthesis Sania Saheli a, Ali Reza Rezvani a,*, Vaclav Eigner b a

Department of Chemistry, University of Sistan and Baluchestan, P. O. Box 98135-674, Zahedan, Iran

b

Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Prague 8, Czech Republic

*E-mail address: [email protected]

Abstract Catalyst structural features are known to strongly affect the Fischer-Tropsch synthesis (FTS). In this study, in order to improve catalytic activity, novel Co-Ni catalysts are synthesized via a new synthetic route. In doing so, the Co-Ni/SiO2 or Al2O3 catalysts prepared by thermal decomposition of inorganic precursors (synthesized catalyst) are compared to those prepared using impregnation (reference catalyst). Catalytic performances are evaluated in the fixed bed micro reactor. Superior activity by the synthesized catalysts was observed in the FTS which can be attributed to structural properties such as small particle size, high surface area and homogenous dispersion of the active phase. Keywords: Inorganic precursor; Clean fuels; Fischer-Tropsch synthesis; Cobalt-based catalyst; Promoter. 1. Introduction The Fischer-Tropsch synthesis (FTS) represents a tried and true process for the production of clean fuels and chemicals from syngas [1-5]. FTS is a heterogeneous catalytic process that accelerates in the presence of transition metals such as Co, Fe, Ni, and Ru. The carbide mechanism is widely accepted for FTS [6,7]. Initially, CHx monomers are formed on the surface of the metal catalyst while the subsequent coupling of these monomers leads to the production of different intermediates. Various hydrocarbons can be formed via hydrogenation or dehydrogenation of these intermediates, making the selection of appropriate catalysts a nontrivial task. Cobalt is widely used in FTS given its high activity and low price as well as its low tendency to the water–gas shift reaction [8-10]. The addition of promoters to cobalt-based catalysts can improve their catalytic performance [11-17]. For instance, Du et al. [18] reported

that a Zn–Al2O3 supported cobalt catalyst displayed higher activity in the FTS which is caused by the zinc-reduced cobalt-support interaction and increased cobalt reducibility. Furthermore, Ishihara et al. [19] found that, by adding nickel to cobalt-based catalysts, one can promote catalytic performance since nickel affects both reduction and hydrogen adsorption. So far, a number of procedures including impregnation, co-precipitation and Sol-gel [20-23] have been used to prepare mixed metal catalysts. An inorganic precursor can also be utilized since the technique is likely to improve catalytic performance by increasing the surface area as a result of decreased particle size. Moreover, given the close proximity of metals in inorganic complexes, homogenous dispersion becomes more attainable [24-29]. In this paper, a novel inorganic complex [Co0.613Ni1.387(pydc)2(H2O)5].2H2O is synthesized and used to produce mixed metal inorganic precursors. Both Co-Ni/SiO2 or Al2O3 catalysts produced from inorganic precursors (synthesized catalysts) and Co-Ni/SiO2 or Al2O3 catalysts prepared by impregnation method (reference catalysts) were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller method (BET). Both catalysts are evaluated in terms of activity at a fixed-bed micro reactor. 2. Experimental 2.1. Synthesis of [Co0.613Ni1.387(pydc)2(H2O)5]. 2H2O (1) 176 mg pyridine-2,6-dicarboxylic acid (99%,Merck) was dissolved in a 10 ml distilled water and then 5 ml distilled water containing 80 mg NaOH (98%,Sigma) was added to the solution. An aqueous solution of Co(NO3)2 .6H2O (145.5 mg) (99%,Merck) and Ni(NO3)2 .6H2O (145.35 mg) (99%,Merck) were dissolved in 5 ml distilled water and then added to the above-mentioned solution. The resulting solution was refluxed for two days. Following the completion of the reaction, the solution was kept at room temperature and a suitable crystal of 1 for single crystal X-ray diffraction analysis was obtained after a few days. The yield was 78%. Anal. Calc. for C14H20Co0.613N2Ni1.387O15: C, 29.30; H, 3.51; N: 4.88. Found: C, 28.80; H, 3.53; N: 4.86 %.

2.2. Catalysts preparation The catalysts precursors [Co0.613Ni1.387(pydc)2(H2O)5].2H2O/SiO2 or Al2O3 were prepared by mixing 0.5 g of alumina or silica with an aqueous solution including 3.2 g of the complex 1. The suspension was stirred and aged at 60 °C in a rota-evaporator for 5 h. The final mixture was filtrated and dried in an oven at 100°C for 10 hours. The inorganic precursors were calcined at 500 °C in an electric furnace at the atmosphere of static air for 5 h. The reference catalysts were prepared by using an aqueous solution of cobalt nitrate (0.74 g) and nickel nitrate (1.73 g) mixed by 0.5 g of silica or alumina under impregnation condition. The suspension was stirred and heated at 60 °C in a rota-evaporator and kept at this temperature for 4 h. The resulting precipitate was obtained by filtration and then dried in an oven at 100°C for 10 hours. Thereafter, the catalysts precursors were calcined at 500 °C for 5 h. 2.3. Instruments Elemental analysis was performed by using a Leco, CHNS-932 elemental analyzer. The FT-IR spectra were collected on Perkin Elmer (spectrum two) spectrophotometer with KBr pellets in the 4000–400 cm−1 range. The thermal behavior of complex 1 was investigated by using NETZSCH STA 409 PC/PG equipment. The sample (19.494 mg) was placed in an alumina cell and heated from 30 to 700 ℃ at heating rate 10℃ min -1 with air as a flowing gas at a rate of 50 ml min -1. The XRD measurements were carried out on a Bruker D8 ADVANCE by using CuKα radiation (λ = 1.54056 Å) at 2θ range from 10° to 80° at a scan rate of 0.02°. The SEM images were collected on KYKY-EM3900M operating at 25 kV. The TEM micrographs were collected by Philips EM208 S. The BET surface areas of the samples were measured by N2 physisorption using an ASAP 2020 apparatus. Each sample was degassed under nitrogen atmosphere at 350 °C for 4 h. 2.4. X-ray structure determination Crystallographic data of complex 1 were collected on a Rigaku OD SuperNova diffractometer equipped with an Atlas S2CCD detector using mirror collimated Mo-Kα radiation (λ = 0.71073 Å).Data reduction, absorption correction, and scaling were performed using CrysAlis PRO [30]. The crystal structure was solved by charge flipping methods with the Superflip program [31] and

refined by full-matrix least-squares on F2 using the program Jana 2006 [32]. The MCE program [33] was used for visualization of electron density maps. All hydrogen atoms were discernible in difference Fourier maps and could be refined to reasonable geometry. According to common practice, H atoms bonded to C were kept in ideal positions, while positions of H atoms bonded to O were refined with restrained geometry. In both cases Uiso(H) was set to 1.2Ueq(C,O). All nonhydrogen atoms were refined using harmonic refinement. The mixed site disorder was refined with occupancy constrained to full occupancy for each position. The resulting occupancy was 597:403 (Co1:Ni1) and 16:984(Co2:Ni2). The crystallographic data and structure determination are shown in Table 1. 2.5. Catalyst testing FTS was performed in a fixed bed micro reactor. Prior to the reactor test, 0.1 g catalyst was reduced in-situ in a mixture of hydrogen/nitrogen gas (flow rate of each gas was 30 mL min-1) at 400 °C for 8 h under 2 bar pressure. After the reduction, the reactor was cooled to the 260 °C and the reduced catalyst was exposed to the synthesis gas H2/CO (2:1) while the pressure was increased to 5 bar. The catalytic performance of the catalyst was evaluated in the temperature range of 260-340℃. The gas chromatograph (Thermo ONIX UNICAM PROGC+) equipped with sample loop, two Thermal Conductivity Detectors (TCD), and one Flame Ionization Detector (FID) was employed for online analysis of the reactant and product streams. The analysis of H2 and CO was carried out by TCD while the FID was applied for the analysis of hydrocarbons. The contents of the sample loop were automatically injected into a capillary column, and each run of the GC analysis lasted more than 30 min. It should be noted that all the catalytic tests were performed on the two different batches. However, as the results were almost identical, only the superior set is reported here. CO conversion and selectivity of the products were calculated via the following equations: (A) CO conversion % = {[(Mols of COin) - (Mols of COout)] / Mols of COin} × 100 (B) Selectivity of j product (%) = {Mols of j product / [(Mols of COin) - (Mols of COout)]} × 100

3. Results and Discussion 3.1. Characterization of the complex Complex 1was crystallized as a dihydrate in the monoclinic system with the space group P21/c. Two mixed-site metal centers containing cobalt and nickel were found in the complex. Metal center 1was coordinated by five water molecules and one oxygen atom of bridging pydc ligand. Metal center 2 was coordinated by four oxygen and two nitrogen atoms from two pydc ligands (see Fig. 1). Both metal centers were found to be six coordinated in a distorted octahedral geometry. The distortions were more pronounced at metal center 2, with angles O1a–Co2|Ni2–O3a and O1b– Co2|Ni2–O3b deviating by more than 25 ° (see table 2). These distortions are caused by the geometric restrictions of tridentate pydc ligand. This compound has good agreement in terms of bond lengths and bond angles with other cobalt (II) and nickel (II) complexes [34,35]. The presence of intermolecular and intramolecular hydrogen bonds between carboxylate groups, coordinated and uncoordinated water molecules plays a significant role in stabilizing and formation of a three-dimensional structure (Fig. 2.). The hydrogen bonds are listed in Table 3.

Information about the thermal behavior of complex 1 was collected by performing a thermogravimetric analysis (TGA), as shown in Fig. 3. The first step of the thermal decomposition was observed in the temperature region of 60-180 °C. This peak was assigned to the elimination of coordinated and uncoordinated water molecules, respectively. The second step was observed in two stages in the temperature range of 360-480 °C. This peak was assigned to the decomposition of organic parts. The Differential Thermal Analysis (DTA) curve (Fig. 3.) is in good agreement with the results of TGA. As seen, two endothermic and one exothermic peaks were identified in the temperature regions of 60-180 °C and 360-480 °C, respectively. These endothermic peaks are

related to the elimination of coordinated and uncoordinated water molecules whereas the exothermic peak pertains to the decomposition of the organic parts. 3.2. Catalysts characterization The FT-IR spectra of the synthesized catalysts are displayed in Fig. 4. FT-IR spectrums of both catalysts exhibited stretching and bending vibrations (3400 cm‒1and 1600 cm‒1) related to the physically absorbed water molecules. The characteristic bands of silica groups appeared at 1102, 877, 594 and 535 cm‒1 [36]. The stretching vibrations of Ni-O and Co-O for the silica-supported catalyst were observed at 471 and 634 cm‒1 while these bands occurred at 458 and 637 cm‒1 in the spectrum of the alumina-supported catalyst [37,38]. Moreover, the stretching and bending modes of AlO6 emerged at 879, 631 and 561 cm‒1[39]. As shown in Figs 5 and 6, further structural investigation of the catalysts was performed by XRD technique. XRD patterns of the silica- and alumina-synthesized catalysts displayed the same phases including NiO (identified peaks at 2Ɵ= 37.2, 43.2, 62.8, 75.4°),Co3O4 (identified peaks at 2θ= 31.2, 36.8, 59.3, 65.2°), and NiCo2O4 (identified peaks at 2θ= 31.1, 36.7, 59.1, 64.9°).The XRD patterns of the reference catalysts exhibited three phases: NiO (identified peaks at 2Ɵ= 37.2, 43.2, 62.8, 75.3°), CoCo2O4 (identified peaks at 2θ= 31.3, 36.5, 55.1, 59, 64.5°), and NiCo2O4 (identified peaks at 2θ= 31.3, 36.6, 44.5, 55.1, 58.9°). In addition, Scherrer's equation was used to determine crystallite sizes yielding 21 and 28 nm for the Co-Ni/SiO2 or Al2O3 synthesized catalysts and 30 and 31 nm for the reference catalysts, respectively. The morphologies of Co-Ni synthesized and reference catalysts are presented in Fig. 7. Their SEM images are indicative of different morphological features: agglomeration and particle sizes of the synthesized catalysts are smaller in comparison with the reference catalysts. The metal compositions of the synthesized and reference catalysts obtained from EDS data are given in

Table 4. As evident, the synthesized catalysts contain higher percentages of cobalt and nickel, which can be attributed to the application of the synthetic route in their preparation The TEM micrographs of the synthesized and reference catalysts are displayed in Fig. 8. The average crystallite sizes were respectively 14 and 16 nm for the synthesized catalysts with the SiO2 and Al2O3 support, while for the reference catalysts these values were 24 and 27 nm. The TEM results show that preparation of Co-Ni catalysts via thermal decomposition of inorganic precursors yields smaller crystallite sizes. In order to measure the surface area of the catalysts, the BET method was performed (Table. 5). The surface area was detected to be 103 and 98 m2/g for the silica and alumina synthesized catalyst, respectively, while the surface areas of reference catalysts are 45 and 43 m 2/g. The higher surface area of the synthesized catalysts in comparison to that of the reference catalysts suggests that the synthesized catalysts have smaller particle sizes. 3.3. Catalytic test Catalytic measurements were performed at the temperature range of 260-340℃ with H2/CO ratio of 2 and P= 5 bar. The temperature effect on CO conversion of the catalysts is shown in Fig. 9. As observed, the CO conversion of the catalysts increases with rising temperature. This is caused by the fact that carbon monooxide dissociation promotes with increasing temperature. The temperature efficacy on the selectivity of the catalysts is shown in Tables 6 to 9. Based on the obtained results, the synthesized catalysts have maximum C2-C4 selectivity and lower methane selectivity at 320℃. At this temperature, the silica-supported Co-Ni synthesized catalyst has about 19% selectivity to olefins and 40% selectivity to paraffins. The alumina-supported Co-Ni synthesized catalyst shows roughly 24% selectivity to olefins and 41% selectivity to

paraffins at 320℃. Additionally, the total values of C4, C5, and C5+ selectivity are nearly 8% for both synthesized catalysts, which is higher than that of the other temperatures we examined in our work. Therefore, the optimal operating temperature for both synthesized catalysts is 320℃. On the other hand, the reference catalysts have higher methane selectivity as well as lower paraffins and olefins selectivity at all studied temperatures. Methane selectivity increases with rising temperature from 260-340 ℃ . However, the selectivity to other hydrocarbons is not significant. These results suggest that the better catalytic performances of the synthesized catalysts prepared by thermal decomposition of inorganic precursors are due to physicochemical features such as smaller particle sizes, homogenous dispersion of active phases and higher surface area. The thermal decomposition of inorganic complexes creates low-density amorphous solids [40]. However, a key parameter in catalytic activity of cobalt-based catalysts is particle size because it can affect product distribution [41,42]. Moreover, the higher surface area of the synthesized catalysts leads to increased Co and Ni surface exposure. These factors ultimately improve catalyst performance. Conclusion In this paper, the effect of mixed metal catalysts on FT reaction was evaluated at the temperature range of 260-340℃. The application of inorganic precursors for preparing Co-Ni synthesized catalysts led to superior catalytic activity. The synthesized catalysts produced acceptable values of parrafins and olefins while the reference catalysts, which were produced via impregnation, had lower activity in the FT reaction under the same conditions. This is because the synthesized catalysts have lower particle sizes and higher surface area. These results prove the effect of the synthetic route on catalyst activity.

Acknowledgements The financial support from the Iranian National Science Foundation (Grant No. 96009657) is gratefully acknowledged. The crystallographic part was supported by the project 18-10504S of the Czech Science Foundation using instruments of the ASTRA lab established within the Operation program Prague Competitiveness - project CZ.2.16/3.1.00/24510. Appendix A. Supplementary data CCDC

1965375

contains

[Co0.613Ni1.387(pydc)2(H2O)5].2H2O.

the

supplementary

These

data

can

be

crystallographic obtained

free

of

data

for

charge

via

http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: [email protected]. References [1] Steynberg, A.P. and Nel, H.G., 2004. Clean coal conversion options using Fischer–Tropsch technology. Fuel, 83(6), pp.765-770. [2] Schulz, H., 1999. Short history and present trends of Fischer–Tropsch synthesis. Applied Catalysis A: General, 186(1-2), pp.3-12. [3] Anderson, R.B., Kölbel, H. and Ralek, M., 1984. The fischer-tropsch synthesis (Vol. 16). New York: Academic Press. [4] Schulz, H., 1999. Short history and present trends of Fischer–Tropsch synthesis. Applied Catalysis A: General, 186(1-2), pp.3-12. [5] Dry, M.E., 2002. The fischer–tropsch process: 1950–2000. Catalysis today, 71(3-4), pp.227241. [6] Iglesia, E., 1997. Design, synthesis, and use of cobalt-based Fischer-Tropsch synthesis catalysts. Applied Catalysis A: General, 161(1-2), pp.59-78.

[7] Kang, X., Zhenghong, B., Xingzhen, Q., Xinxing, W., ZHONG, L., Kegong, F.A.N.G., Minggui, L.I.N. and Yuhan, S., 2013. Advances in bifunctional catalysis for higher alcohol synthesis from syngas. Chinese journal of catalysis, 34(1), pp.116-129. [8] Khodakov, A.Y., Chu, W. and Fongarland, P., 2007. Advances in the development of novel cobalt Fischer− Tropsch catalysts for synthesis of long-chain hydrocarbons and clean fuels. Chemical reviews, 107(5), pp.1692-1744. [9] Dry, M.E., 2002. High quality diesel via the Fischer–Tropsch process–a review. Journal of Chemical Technology & Biotechnology: International Research in Process, Environmental & Clean Technology, 77(1), pp.43-50. [10] Soled, S.L., Iglesia, E., Fiato, R.A., Baumgartner, J.E., Vroman, H. and Miseo, S., 2003. Control of metal dispersion and structure by changes in the solid-state chemistry of supported cobalt Fischer–Tropsch catalysts. Topics in catalysis, 26(1-4), pp.101-109. [11] Pardo-Tarifa, F., Cabrera, S., Sanchez-Dominguez, M. and Boutonnet, M., 2017. Cepromoted Co/Al2O3 catalysts for Fischer–Tropsch synthesis. International journal of hydrogen energy, 42(15), pp.9754-9765. [12] Hong, J., Chu, W., Chernavskii, P.A. and Khodakov, A.Y., 2010. Effects of zirconia promotion on the structure and performance of smaller and larger pore silica-supported cobalt catalysts for Fischer–Tropsch synthesis. Applied Catalysis A: General, 382(1), pp.28-35. [13] Feyzi, M., Khodaei, M.M. and Shahmoradi, J., 2012. Effect of preparation and operation conditions on the catalytic performance of cobalt-based catalysts for light olefins production. Fuel processing technology, 93(1), pp.90-98. [14] Balonek, C.M., Lillebø, A.H., Rane, S., Rytter, E., Schmidt, L.D. and Holmen, A., 2010. Effect of alkali metal impurities on Co–Re catalysts for Fischer–Tropsch synthesis from biomass-derived syngas. Catalysis letters, 138(1-2), pp.8-13.

[15] Zhang, H., Chu, W., Zou, C., Huang, Z., Ye, Z. and Zhu, L., 2011. Promotion effects of platinum and ruthenium on carbon nanotube supported cobalt catalysts for Fischer–Tropsch synthesis. Catalysis letters, 141(3), pp.438-444. [16] Werner, S., Johnson, G.R. and Bell, A.T., 2014. Synthesis and characterization of supported cobalt–manganese

nanoparticles

as

model

catalysts

for

Fischer–Tropsch

synthesis.

ChemCatChem, 6(10), pp.2881-2888. [17] Madikizela-Mnqanqeni, N.N. and Coville, N.J., 2008. The effect of sulfur addition during the preparation of Co/Zn/TiO2 Fischer–Tropsch catalysts. Applied Catalysis A: General, 340(1), pp.7-15. [18] Du, J., Yan, J., Hong, J., Zhang, Y., Chen, S. and Li, J., 2015. Catalytic performance of Co/Zn–Al 2 O 3 Fischer–Tropsch catalysts: a comparative study of zinc introduction methodologies. RSC Advances, 5(74), pp.60534-60540. [19] Ishihara, T., Horiuchi, N., Inoue, T., Eguchi, K., Takita, Y. and Arai, H., 1992. Effect of alloying on CO hydrogenation activity over SiO 2-supported Co-Ni alloy catalysts. Journal of Catalysis, 136(1), pp.232-241. [20]Mansouri, M., Atashi, H., Tabrizi, F.F., Mansouri, G. and Setareshenas, N., 2014. Fischer– Tropsch synthesis on cobalt–manganese nanocatalyst: studies on rate equations and operation conditions. International Journal of Industrial Chemistry, 5(2), p.14. [21]Fegley Jr, B., White, P. and Bowen, H.K., 1985. Preparation of Zirconia‐Alumina Powders by Zirconium Alkoxide Hydrolysis. Journal of the American Ceramic Society, 68(2), pp.C-60. [22]Trépanier, M., Tavasoli, A., Dalai, A.K. and Abatzoglou, N., 2009. Co, Ru and K loadings effects on the activity and selectivity of carbon nanotubes supported cobalt catalyst in Fischer– Tropsch synthesis. Applied Catalysis A: General, 353(2), pp.193-202. [23] Ma, W., Jacobs, G., Sparks, D.E., Gnanamani, M.K., Pendyala, V.R.R., Yen, C.H., Klettlinger, J.L., Tomsik, T.M. and Davis, B.H., 2011. Fischer–Tropsch synthesis: Support and cobalt cluster size effects on kinetics over Co/Al2O3 and Co/SiO2 catalysts. Fuel, 90(2), pp.756765.

[24] Saheli, S., Rezvani, A.R., Malekzadeh, A., Dusek, M. and Eigner, V., 2018. Novel inorganic precursors [Co4.32Zn1.68(HCO2)18(C2H8N)6]/SiO2 and [Co4.32Zn1.68(HCO2)18(C2H8N)6]/Al2O3 for Fischer–Tropsch synthesis. International Journal of Hydrogen Energy, 43(2), pp.685-694. [25] Saheli, S., Rezvani, A.R., Malekzadeh, A., Dusek, M. and Eigner, V., 2018. Effect of Synthetic Route and Metal Oxide Promoter on Cobalt-Based Catalysts for Fischer–Tropsch Synthesis. Catalysis Letters, 148(11), pp.3557-3569. [26] Saheli, S., Rezvani, A.R. and Malekzadeh, A., 2017. Study of structural and catalytic properties of Ni catalysts prepared from inorganic complex precursor for Fischer-Tropsch synthesis. Journal of Molecular Structure, 1144, pp.166-172. [27] Razmara, Z., Rezvani, A.R. and Saravani, H., 2017. Fischer–Tropsch reaction over a Co2-NiMn/SiO2 nanocatalyst prepared by thermal decomposition of a new precursor. Chemical Papers, 71(4), pp.849-856. [28] Janani, H., Rezvani, A.R., Grivani, G.H. and Mirzaei, A.A., 2016. Preparation and characterization of a new cobalt hydrazone complex and its catalytic activity in the hydrogenation of carbon monoxide (Fischer–Tropsch synthesis). Reaction Kinetics, Mechanisms and Catalysis, 117(1), pp.189-203. [29] Janani, H., Rezvani, A.R., Grivani, G.H. and Mirzaei, A.A., 2015. Fischer–Tropsch Synthesis of Hydrocarbons over New Co/Ce Bimetallic Catalysts Derived from Dipicolinate and Carbonyl Metal Complexes. Journal of Inorganic and Organometallic Polymers and Materials, 25(5), pp.1169-1182. [30] CrysAlis, P.R.O., 2014. Agilent Technologies Ltd. Yarnton, Oxfordshire, England. [31] Palatinus, L. and Chapuis, G., 2007. SUPERFLIP–a computer program for the solution of crystal structures by charge flipping in arbitrary dimensions. Journal of Applied Crystallography, 40(4), pp.786-790. [32] Petříček, V., Dušek, M. and Palatinus, L., 2014. Crystallographic computing system JANA2006: general features. Zeitschrift für Kristallographie-Crystalline Materials, 229(5), pp.345352.

[33] Hušák, M. and Kratochvíl, B., 2003. MCE–program for fast interactive visualization of electron and similar density maps, optimized for small molecules. Journal of Applied Crystallography, 36(4), pp.1104-1104. [34] Derikvand, Z., Dorosti, N., Hassanzadeh, F., Shokrollahi, A., Mohammadpour, Z. and Azadbakht, A., 2012. Three new supramolecular compounds of copper (II), cobalt (II) and zirconium (IV) with pyridine-2, 6-dicarboxylate and 3, 4-diaminopyridine: Solid and solution states studies. Polyhedron, 43(1), pp.140-152. [35] Ghadermazi, M., Manteghi, F., Mehdizadeh, S., Kakaei, N., Shokrollahi, A., Malekhosseini, Z. and Shamsipur, M., 2011. A proton transfer and a nickel (II) compound including pyridine-2, 6dicarboxylate and Phenylhydrazinium ions: Synthesis, characterization, crystal structure and solution study. Journal of the Iranian Chemical Society, 8(4), pp.919-930. [36] Fixman, E.M., Abello, M.C., Gorriz, O.F. and Arrúa, L.A., 2007. Preparation of Cu/SiO 2 catalysts with and without tartaric acid as template via a sol–gel process: Characterization and evaluation in the methanol partial oxidation. Applied Catalysis A: General, 319, pp.111-118. [37] El-Kemary, M., Nagy, N. and El-Mehasseb, I., 2013. Nickel oxide nanoparticles: synthesis and spectral studies of interactions with glucose. Materials Science in Semiconductor Processing, 16(6), pp.1747-1752. [38] Sharifi, S.L., Shakur, H.R., Mirzaei, A. and Hosseini, M.H., 2013. Characterization of cobalt oxide Co3O4 nanoparticles prepared by various methods: effect of calcination temperatures on size, dimension and catalytic decomposition of hydrogen peroxide. International Journal of Nanoscience and Nanotechnology, 9(1), pp.51-58. [39] Ma, M.G. and Zhu, J.F., 2009. A facile solvothermal route to synthesis of γ-alumina with bundle-like and flower-like morphologies. Materials Letters, 63(11), pp.881-883. [40] Soled, S.L., Iglesia, E., Miseo, S., DeRites, B.A. and Fiato, R.A., 1995. Selective synthesis of α-olefins on Fe-Zn Fischer-Tropsch catalysts. Topics in Catalysis, 2(1-4), pp.193-205. [41] Iglesia, E., 1997. Design, synthesis, and use of cobalt-based Fischer-Tropsch synthesis catalysts. Applied Catalysis A: General, 161(1-2), pp.59-78.

[42] Prieto, G., Martínez, A., Concepción, P. and Moreno-Tost, R., 2009. Cobalt particle size effects in Fischer–Tropsch synthesis: structural and in situ spectroscopic characterisation on reverse micelle-synthesised Co/ITQ-2 model catalysts. Journal of Catalysis, 266(1), pp.129-144.

Fig. 1. A labeled view of compound1. Ellipsoids drawn at 50 % probability level.

Fig. 2.The hydrogen bonding in the complex 1. Ellipsoids drawn at 50 % probability level.

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c

d

Fig. 8. TEM images of a) Co-Ni/SiO2 synthesized catalyst, b) Co-Ni/Al2O3 synthesized catalyst c) Co-Ni/SiO2 reference catalyst and d) Co-Ni/Al2O3 reference catalyst.

90

Conversion (%)

80 70

Co-Ni/Al2O3 Synthesized catalyst Co-Ni/SiO2 Synthesized catalyst Co-Ni/SiO2 reference catalyst Co-Ni/Al2O3 reference catalyst

60 50 40 30 20 10

0 260

280

300

320

340

Temperature ℃

Fig. 9. Temperature affect on CO conversion percentage of synthesized and reference catalysts.

Table 1 Crystallography data for[Co0.613Ni1.387(pydc)2(H2O)5]. 2H2O.

Complex Empirical formula Formula Weight Crystal system Space group Crystal size (mm3) a (Å) b (Å) c (Å) 𝛼 (°) β (°) 𝛾(°) V (Å3) Z Dcalcd(g cm–3) T (K) Reflections collected /unique Rint Limiting indices

Tmin, Tmax (sin θ/λ)max (Å−1) R[F2> 3σ(F2)], wR(F2), S Δρmax, Δρmin (e Å−3)

1 C14H20Co0.613N2Ni1.387O15 573.8 Monoclinic P21/c 0.18 × 0.11 × 0.04 8.3348 (1) 26.9839 (5) 9.6408 (2) 90 98.3755 (14) 90 2145.14 (7) 4 1.7768 95 24213/4312 0.027 -7≤h≤10 -33≤k≤33 -12≤l≤11 0.693, 0.901 0.624 0.021, 0.066, 1.28 0.27, −0.24

Table 2 Selected bond lengths (Å) and bond angles (°) for [Co0.613Ni1.387(pydc)2(H2O)5]. 2H2O. Bond Lengths Bond Angles

Co1|Ni1—O2b Co1|Ni1—O1w Co1|Ni1—O2w Co1|Ni1—O3w Co1|Ni1—O4w Co1|Ni1—O5w Co2|Ni2—O1a Co2|Ni2—O3a Co2|Ni2—O1b Co2|Ni2—O3b Co2|Ni2—N1a Co2|Ni2—N1b

2.0619(9) 2.0700(9) 2.1514(11) 2.0513(12) 2.0683(10) 2.0432(10) 2.0998(11) 2.1561(11) 2.1698(9) 2.1647(9) 1.9681(11) 1.9765(11)

O2b—Co1|Ni1—O1w O2b—Co1|Ni1—O5w O1w—Co1|Ni1—O2w O2w—Co1|Ni1—O3w O3w—Co1|Ni1—O4w O4w—Co1|Ni1—O5w O1a—Co2|Ni2—O3a O1a—Co2|Ni2—N1b O3a—Co2|Ni2—O1b O1b—Co2|Ni2—O3b O3b—Co2|Ni2—N1a N1a—Co2|Ni2—N1b

171.69(4) 80.43(4) 85.41(4) 177.02(4) 86.89(4) 171.00(4) 154.96(4) 102.72(4) 93.56(4) 154.56(4) 108.30(4) 174.64(4)

Table 3 Hydrogen bonds data for[Co0.613Ni1.387(pydc)2(H2O)5]. 2H2O(Å,°). D–H···A d(D–H) d(H···A) d(D···A) i

<(DHA)

O1w—H1o1w—O7w 0.820(13) 1.836(13) 2.6459(15) 169.1(14) O1w—H2o1w—O3bii 0.820(13) 1.947(12) 2.7636(13) 174.1(13) iii O2w—H1o2w—O4b 0.820(8) 1.871(9) 2.6847(13) 171.3(18) O2w—H2o2w—O3aiv 0.820(13) 1.992(13) 2.7956(14) 166.5(13) O3w—H1o3w—O6wv 0.820(13) 2.021(13) 2.8179(15) 164.0(17) vi O3w—H2o3w—O2a 0.820(15) 1.889(15) 2.7072(15) 176.2(18) O4w—H1o4w—O4aiv 0.820(14) 1.864(14) 2.6801(15) 173.1(16) O4w—H2o4w—O1b 0.820(11) 2.057(13) 2.8299(13) 157.0(16) O5w—H1o5w—O6w 0.820(11) 2.135(10) 2.9237(14) 161.3(14) ii O5w—H2o5w—O4b 0.820(13) 1.812(13) 2.6309(14) 176.2(17) O6w—H1o6w—O2wvii 0.820(11) 2.116(11) 2.9074(13) 162.1(15) iii O6w—H2o6w—O1a 0.820(10) 2.297(12) 3.0404(13) 151.1(16) O7w—H1o7w—O2ai 0.820(4) 1.986(6) 2.7634(15) 158.0(17) O7w—H2o7w—O4aiv 0.820(12) 1.953(12) 2.7730(15) 177.3(19) Symmetry code: (i) x, 0.5-y, -0.5+z; (ii) -1+x, y, -1+z; (iii) 2-x, 1-y, 1-z; (iv) -1+x, y, z; (v) 2-x, 1-y, -z; (vi) x, y, -1+z; (vii) 1-x, 1-y, -z.

Table 4 EDS data of synthesized and reference catalysts. Catalyst

Element Co(Wt.%) EDS 19.31 20.34 12.23 13.75

Co-Ni/SiO2 synthesized catalyst Co-Ni/Al2O3 synthesized catalyst Co-Ni/SiO2 reference catalyst Co-Ni/Al2O3 reference catalyst

Ni(Wt.%) EDS 25.65 27.17 18.78 19.45

Table 5 BET results of synthesized and reference catalysts. synthesized Sample BET surface area (m2/g) Co-Ni/SiO2 91

reference Sample Co-Ni/SiO2

Co-Ni/Al2O3

Co-Ni/Al2O3

104

BET surface area (m2/g) 40 42

Table 6 Catalytic performances of Co-Ni/SiO2 synthesized catalyst. Temperature (℃)

SCH4(%)

SC2H4(%)

SC2H6(%)

SC3H6(%)

SC3H8(%)

SC4(%)

SC5(%)

SC5+(%)

260

39.03

11.23

12.22

2.86

12.70

1.06

0.087

2.70

280

36.40

13.24

16.73

5.86

13.98

1.07

0.09

3.38

300

28.10

14.45

22.99

7.60

16.50

2.00

0.13

5.88

320

28.20

15.30

23.20

8.01

17.00

2.20

0.06

6.04

340 S: Selectivity

34.01

13.33

21.15

7.24

15.28

2.08

0.01

4.36

Table 7 Catalytic performances of Co-Ni/Al2O3 synthesized catalyst. SCH4(%)

SC2H4(%)

SC2H6(%)

SC3H6(%)

SC3H8(%)

SC4(%)

SC5(%)

SC5+(%)

260

38.12

12.20

11.87

3.65

12.83

1.20

0.08

5.25

280

35.73

14.04

17.59

5.20

14.04

2.28

0.09

6.14

300

27.64

15.69

23.25

7.53

16.16

2.25

0.10

6.22

320

25.30

16.05

24.00

8.00

17.43

2.34

0.07

6.50

340 S: Selectivity

32.07

14.87

21.29

7.54

17.36

2.18

0.04

4.30

Temperature (℃)

Table 8 Catalytic performances of Co-Ni/SiO2 reference catalyst. Temperature (℃)

SCH4(%)

SC2H4(%)

SC2H6(%)

SC3H6(%)

SC3H8(%)

SC4(%)

SC5(%)

260

43.70

6.20

8.96

0.14

6.19

0.64

2.35

280

48.80

7.00

9.29

0.42

7.34

0.58

2.47

300

51.61

7.84

9.30

0.24

9.00

0.45

0.1

320

52.89

7.60

7.09

0.28

7.11

0.47

0.74

340 S: Selectivity

56.30

5.34

6.70

0.27

7.00

0.45

0.73

Table 9 Catalytic performances of Co-Ni/Al2O3 reference catalyst. Temperature (℃)

SCH4(%)

SC2H4(%)

SC2H6(%)

SC3H6(%)

SC3H8(%)

SC4(%)

SC5(%)

260

42.00

7.00

8.72

0.13

7.19

0.54

1.35

280

46.39

7.16

9.50

0.32

7.80

0.48

1.64

300

50.00

8.04

9.14

0.14

8.57

0.35

0.98

320

53.89

7.90

8.85

0.18

8.11

0.37

0.64

340 S: Selectivity

55.3

7.34

0.17

7.54

0.35

0.63

6.24

Author Contributions Section Sania Saheli: Conceptualization, Methodology, Software, Data curation, WritingOriginal draft preparation, Visualization, Investigation. Ali Reza Rezvani : Supervision, Project administration, Reviewing and Editing. Vaclav Eigner: Software, Data curation, Visualization, Investigation, WritingReviewing and Editing.