Hydroprocessing of Oleic Acid for Production of Jet-Fuel Range Hydrocarbons over Cu and FeCu Catalysts

: In the present study, a series of monometallic Cu / SiO 2 -Al 2 O 3 catalysts exhibited immense potential in the hydroprocessing of oleic acid to produce jet-fuel range hydrocarbons. The synergistic e ﬀ ect of Fe on the monometallic Cu / SiO 2 -Al 2 O 3 catalysts of variable Cu loadings (5–15 wt%) was ascertained by varying Fe contents in the range of 1–5 wt% on the optimized 13% Cu / SiO 2 -Al 2 O 3 catalyst. At 340 ◦ C and 2.07 MPa H 2 pressure, the jet-fuel range hydrocarbons yield and selectivities of 51.8% and 53.8%, respectively, were recorded for the Fe(3)-Cu(13) / SiO 2 -Al 2 O 3 catalyst. To investigate the inﬂuence of acidity of support on the cracking of oleic acid, ZSM-5 (Zeolite Socony Mobil–5) and HZSM-5(Protonated Zeolite Socony Mobil–5)-supported 3% Fe-13% Cu were also evaluated at 300–340 ◦ C and 2.07 MPa H 2 pressure. Extensive techniques including N 2 sorption analysis, pyridine- Fourier Transform Infrared Spectroscopy (Pyridine-FTIR), X-ray Di ﬀ raction (XRD), X-ray Photoelectron Spectroscopy (XPS), and H 2 -Temperature Programmed Reduction (H 2 -TPR) analyses were used to characterize the materials. XPS analysis revealed the existence of Cu 1 + phase in the Fe(3)-Cu(13) / SiO 2 -Al 2 O 3 catalyst, while Cu metal was predominant in both the ZSM-5 and HZSM-5-supported FeCu catalysts. The lowest crystallite size of Fe(3)-Cu(13) / SiO 2 -Al 2 O 3 was conﬁrmed by XRD, indicating high metal dispersion and corroborated by the weakest metal–support interaction revealed from the TPR proﬁle of this catalyst. CO chemisorption also conﬁrmed high metal dispersion (8.4%) for the Fe(3)-Cu(13) / SiO 2 -Al 2 O 3 catalyst. The lowest and mildest Brønsted / Lewis acid sites ratio was recorded from the pyridine–FTIR analysis for this catalyst. The highest jet-fuel range hydrocarbons yield of 59.5% and 73.6% selectivity were recorded for the Fe(3)-Cu(13) / SiO 2 -Al 2 O 3 catalyst evaluated at 300 ◦ C and 2.07 MPa H 2 pressure, which can be attributed to its desirable textural properties, high oxophilic iron content, high metal dispersion and mild Brønsted acid sites present in this catalyst.


Introduction
The aviation sector is a large growing sector which bridges large distances within relatively short time. The total number of international air passengers worldwide in 2018 was 4.4 billion, and this is expected to increase to 7.8 billion in 2036 with Compound Annual Growth Rate (CAGR) of 3.6% according to the prediction made by the International Air Transport Association (IATA). The aviation sector facilitates 35% of world trade by value and it is responsible for transporting 54% of international tourists. In spite of the significance of this sector, it is being faced by challenges over the years. The worldwide aviation industry consumes about 1.7 billion barrels of conventional jet fuel annually [1]. The development of the aviation industry is paralleled with increase in greenhouse gas emissions [2]. 350 • C and 4 MPa H 2 pressure. The catalysts supported by the mixture of silica and alumina gave the highest and the most desirable iso/normal ratio (0. 26). This shows clearly that SiO 2 -Al 2 O 3 -supported catalysts have more preference for hydroprocessing of vegetable oils for bio-jet fuel production as compared to the Al 2 O 3 -and SiO 2 -supported catalysts. Amorphous silica alumina support is viewed as a polymer of Al 2 O 3 on a backbone of SiO 2 , while crystalline ZSM-5 and HZSM materials are viewed as copolymers of Al 2 O 3 and SiO 2 with capacities for ion exchange [14]. These three materials have varying Brønsted acid sites concentrations. Hydroprocessing of vegetable oils for production of jet-fuel range hydrocarbon largely depends on Brønsted acid sites concentrations of the catalysts used [8].
In this work, the catalytic performance on the conversion of model compound of vegetable oils (oleic acid), yield and selectivity of jet-fuel range hydrocarbons were studied over the Cu/SiO 2 -Al 2 O 3, FeCu/SiO 2 -Al 2 O 3 , FeCu/ZSM-5 and FeCu/HZSM-5 catalysts. These catalysts were characterized for determination of their physicochemical properties and their impacts on product selectivity. The influence of reaction temperature, contact time and catalyst acidity were also investigated.

N 2 -Adsorption/Desorption Measurement
The N 2 -adsorption/desorption isotherms of all the silica-alumina-supported catalysts and its support are shown in Figure S1. For all the profiles shown in Figure S1, at relatively low pressure, no significant adsorption was observed for the support and the catalysts showed the formation of monolayer of adsorbed molecules of nitrogen gas. Significant adsorption at high relative pressure as shown in Figure S1 indicates adsorption in mesoporous materials [15]. The profiles of the support (SiO 2 -Al 2 O 3 ) and the monometallic catalysts exhibit type IV isotherms indicating that the support and the catalysts are mesoporous. Despite different loadings of iron, the profiles of all the FeCu/SiO 2 -Al 2 O 3 catalysts exhibit type IV isotherm indicating mesoporosity [15]. The pore diameters of the catalysts as shown in Table 1 for all the silica-alumina-supported catalysts and its support confirmed the type IV isotherm in Figure S1. The pore diameters were 4.4-5.7 nm indicating mesoporous nature of material. Out of all the monometallic catalysts, Cu(13)/SiO 2 -Al 2 O 3 catalyst samples have the largest pore diameter of 5.3 nm. Pore diameter decreases with increase in iron loading (1-5 wt%) as shown in Table 1. This trend can be ascribed to pore blockage.   Unlike Fe(3)-Cu(13)/SiO 2 -Al 2 O 3 catalyst and its respective support, Fe(3)-Cu(13)/HZSM-5 and Fe(3)-Cu(13)/ZSM-5 and their respective supports, show no significant adsorption capacity within the relative pressure of 0-0.8. Low nitrogen adsorption occurs at very high relative pressure (p/p o > 0.8), indicating a mixed type I-type IV isotherm. It shows the presence of both micro-and mesoporosity in the two catalyst samples and their respective supports [15].
The textural properties of the three catalysts, (Fe (3) Table 1. The Fe(3)-Cu(13)/SiO 2 -Al 2 O 3 catalyst and its support have only mesoporous volumes, while other samples have both mesoporous and microporous volumes. The pore volume of all the supports decreases after metals loading due to blockage of the pores. Of all the catalyst samples, Fe(3)-Cu(13)/SiO 2 -Al 2 O 3 has the largest surface area, pore volume and pore diameter.

XRD Analysis
The XRD patterns of the silica-alumina-supported catalysts and its support are shown in Figure 1. The 23 • diffraction peak on the diffuse XRD pattern of silica alumina support coincides with the literature [16][17][18][19][20] and the broadness of the peaks shows the material is amorphous. The two peaks at 36 • and 43 • diffraction angles are ascribed to copper (I) oxide [21]. The intensity of the peaks of copper (I) oxide at a 36 • diffraction angle increases with copper loading. Diffraction peaks of copper (II) oxide, copper metal, iron oxides and iron were not observed due to their high dispersion on the support. The 42.5 • diffraction angle peak attributed to copper (I) oxide [21] in the diffractogram of Fe (3) Table 1). Of all the silica-alumina-supported bimetallic catalysts, Fe(3)-Cu(13)/SiO 2 -Al 2 O 3 catalyst has the lowest Cu 2 O crystallite size of 5.9 nm. This indicates its potential of being active for hydroprocessing of oleic acid for production of jet-fuel range hydrocarbons (C 8 -C 16 Figure 2. The X-ray light incident in a periodically arranged crystalline materials scatters in a specific direction and results in high intensity narrow peaks, while the X-ray light incident in amorphous materials scatters in random directions and gives broad peaks. In Figure 2, the discrete X-ray diffraction patterns of HZSM-5 and ZSM-5 supports are sharp Bragg peaks. This shows that these two materials have high degree of crystallinity with long range order. The X-ray diffraction patterns of HZSM-5 and ZSM-5 coincide with that reported in the literature [22,23]. The broad Bragg peak at 23 • diffraction angle on the diffuse XRD pattern of amorphous silica alumina shows that it is amorphous and it also coincides with that reported in the literature [16]. The X-ray diffraction patterns of Fe(3)-Cu(13)/HZSM-5 and Fe(3)-Cu(13)/ZSM-5 show clearly the phases of Cu nanoparticles with the 23 • sharp peak confirming the supports. In all the XRD patterns of FeCu/HZSM-5 and Fe(3)-Cu(13)/ZSM-5 catalysts, the Bragg peaks at 43 • , 51 • and 74 • diffraction angles, respectively, are ascribed to the presence of Cu nanoparticles [24]. These three characteristic diffraction peaks correspond to the (111), (200) and (220) planes of face-centred cubic structure of copper. The peaks at 36 • and 42.5 • in the diffractogram of Fe(3)-Cu(13)/SiO 2 -Al 2 O 3 catalyst are attributed to the presence of copper (I) oxide [21]. The absence of the diffraction peaks of the reduced and oxidized phases of iron in all the samples can be ascribed to the fact that iron may be either present in its noncrystalline phase or in minute quantities below XRD sensitivity.
From the N 2 -adsorption/desorption measurement, the BET surface area of the silica-alumina support is the highest followed by the ZSM-5 support and HZSM-5 support. The catalyst, Fe(3)-Cu(13)/SiO 2 -Al 2 O 3 with the highest surface area, pore diameter and pore volume has the lowest copper phase crystallite size.  Table 1. The Fe(3)-Cu(13)/SiO2-Al2O3 catalyst and its support have only mesoporous volumes, while other samples have both mesoporous and microporous volumes. The pore volume of all the supports decreases after metals loading due to blockage of the pores. Of all the catalyst samples, Fe(3)-Cu(13)/SiO2-Al2O3 has the largest surface area, pore volume and pore diameter.

XRD Analysis
The XRD patterns of the silica-alumina-supported catalysts and its support are shown in Figure  1. The 23° diffraction peak on the diffuse XRD pattern of silica alumina support coincides with the literature [16][17][18][19][20] and the broadness of the peaks shows the material is amorphous. The two peaks at 36° and 43° diffraction angles are ascribed to copper (I) oxide [21]. The intensity of the peaks of copper (I) oxide at a 36° diffraction angle increases with copper loading. Diffraction peaks of copper (II) oxide, copper metal, iron oxides and iron were not observed due to their high dispersion on the  support. The 42.5° diffraction angle peak attributed to copper (I) oxide [21] in the diffractogram of Fe(3)-Cu(13)/SiO2-Al2O3 catalyst is the most diffuse peak. The decrease in the crystallite size of Cu2O in Fe(1)-Cu(13)/SiO2-Al2O3, Fe(2)-Cu(13)/SiO2-Al2O3 and Fe(3)-Cu(13)/SiO2-Al2O3 with iron loading indicates the promotional effect of iron on the dispersion of copper (see Table 1). Of all the silicaalumina-supported bimetallic catalysts, Fe(3)-Cu(13)/SiO2-Al2O3 catalyst has the lowest Cu2O crystallite size of 5.9 nm. This indicates its potential of being active for hydroprocessing of oleic acid for production of jet-fuel range hydrocarbons (C8-C16).
The XRD patterns of the Fe(3)-Cu(13)/SiO2-Al2O3, Fe(3)-Cu(13)/HZSM-5 and Fe(3)-Cu(13)/ZSM-5 catalyst samples and their respective supports are shown in Figure 2. The X-ray light incident in a periodically arranged crystalline materials scatters in a specific direction and results in high intensity narrow peaks, while the X-ray light incident in amorphous materials scatters in random directions and gives broad peaks. In Figure 2, the discrete X-ray diffraction patterns of HZSM-5 and ZSM-5 supports are sharp Bragg peaks. This shows that these two materials have high degree of crystallinity with long range order. The X-ray diffraction patterns of HZSM-5 and ZSM-5 coincide with that reported in the literature [22,23]. The broad Bragg peak at 23° diffraction angle on the diffuse XRD pattern of amorphous silica alumina shows that it is amorphous and it also coincides with that reported in the literature [16]. The X-ray diffraction patterns of Fe(3)-Cu(13)/HZSM-5 and Fe(3)-Cu(13)/ZSM-5 show clearly the phases of Cu nanoparticles with the 23° sharp peak confirming the supports. In all the XRD patterns of FeCu/HZSM-5 and Fe(3)-Cu(13)/ZSM-5 catalysts, the Bragg peaks at 43°, 51° and 74° diffraction angles, respectively, are ascribed to the presence of Cu nanoparticles [24]. These three characteristic diffraction peaks correspond to the (111), (200) and (220) planes of face-centred cubic structure of copper. The peaks at 36° and 42.5° in the diffractogram of Fe(3)-Cu(13)/SiO2-Al2O3 catalyst are attributed to the presence of copper (I) oxide [21]. The absence of the diffraction peaks of the reduced and oxidized phases of iron in all the samples can be ascribed to the fact that iron may be either present in its noncrystalline phase or in minute quantities below XRD sensitivity.

Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) and CO Chemisorption Analyses
The actual loadings of iron and copper in Fe(3)-Cu(13)/SiO 2 -Al 2 O 3 , Fe(3)-Cu(13)/ZSM-5 and Fe(3)-Cu(13)/HZSM-5 catalyst samples evaluated using the ICP-OES shows that they are approximately the same as the targeted loading, if rounded up to the nearest whole number. The exact actual loadings of iron and copper of these three catalyst samples in terms of their weight percentage were used in their CO chemisorption analysis. The crystallite size and percentage dispersion surface area of Cu and Fe metals were calculated using the CO chemisorption method and tabulated in Table 2 Table 2. Metal dispersion of the three catalysts increases with the surface area of their respective support shown in Table 1. This trend can be attributed to increase in the proportion of catalysts' surface atoms with respect to the bulk catalysts. Fe (3)

Fourier Transform Infra-Red Analysis
The molecular structure of Fe (3) The absorption detected at 791 cm −1 , 1065 cm −1 and 1210 cm −1 wavenumbers can be ascribed to the external symmetric stretch, internal asymmetric stretch and external asymmetric stretch, which are typical for extremely siliceous materials [18,25]. The peaks were more intense in ZSM-5 and HZSM because of their higher silica-alumina ratio as compared to that of the silica-alumina support. There was a slight peak shift to a higher wavenumber at 537 cm −1 after Cu and Fe impregnation on HZSM-5 in the framework vibration ascribed to five membered rings tetrahedron shaped MFI zeolites. There was also slight shift of peaks to a higher wavenumber at 1065 cm −1 after Cu and Fe impregnation on ZSM-5 and HZSM-5 in the absorption band ascribed to internal asymmetric stretch of extremely Catalysts 2019, 9, 1051 7 of 21 siliceous materials. These shifts of FTIR peaks after impregnation of Cu and Fe are due to change in bond length of the aluminosilicate frameworks in the catalyst samples [18,25].
zeolites. The absorption detected at 791 cm −1 , 1065 cm −1 and 1210 cm −1 wavenumbers can be ascribed to the external symmetric stretch, internal asymmetric stretch and external asymmetric stretch, which are typical for extremely siliceous materials [18,25]. The peaks were more intense in ZSM-5 and HZSM because of their higher silica-alumina ratio as compared to that of the silica-alumina support. There was a slight peak shift to a higher wavenumber at 537 cm −1 after Cu and Fe impregnation on HZSM-5 in the framework vibration ascribed to five membered rings tetrahedron shaped MFI zeolites. There was also slight shift of peaks to a higher wavenumber at 1065 cm −1 after Cu and Fe impregnation on ZSM-5 and HZSM-5 in the absorption band ascribed to internal asymmetric stretch of extremely siliceous materials. These shifts of FTIR peaks after impregnation of Cu and Fe are due to change in bond length of the aluminosilicate frameworks in the catalyst samples [18,25].

XPS
The XPS spectra of the Fe (3)

XPS
The XPS spectra of the Fe (3) [31]. The atomic compositions of the metal oxides and reduced metals obtained from the XPS spectra fitting were tabulated in Table 3. All the three catalyst samples consist of significant atomic composition of copper and iron in their oxide state, owing to the passivation of the surface of the catalysts during their synthesis. The results also show that all the catalyst samples consist of Fe 2 O 3 in larger quantities as compared to FeO at the surface. The highest surface atomic composition of oxophilic iron metal was observed in the FeCu/SiO 2 -Al 2 O 3 catalyst as revealed from XPS fitting. The varying composition of metals and their oxides in all the catalysts can be ascribed to their different metal-support interactions. of significant atomic composition of copper and iron in their oxide state, owing to the passivation of the surface of the catalysts during their synthesis. The results also show that all the catalyst samples consist of Fe2O3 in larger quantities as compared to FeO at the surface. The highest surface atomic composition of oxophilic iron metal was observed in the FeCu/SiO2-Al2O3 catalyst as revealed from XPS fitting. The varying composition of metals and their oxides in all the catalysts can be ascribed to their different metal-support interactions.

H 2 -TPR Analysis
The

Pyridine FTIR Analysis
Pyridine, ammonia and acetonitrile can be used to determine the Brønsted and Lewis acid sites of the catalysts. In this work, pyridine was used as molecular probe and it shows a clear distinction between the Brønsted and Lewis acid sites. Moreover, the kinetic diameter of pyridine is 0.57 nm which is lower than the 2.1-5.7 nm pore size of the catalysts [36]. Catalysts of high Brønsted/Lewis acidity ratio favours cracking and is also not selective for dehydrogenation [37]. Cracking is desired for hydroprocessing of oleic acid for production of jet-fuel range hydrocarbons and dehydrogenation is undesirable. Pyridine FTIR spectra and Brønsted/Lewis acid sites ratio of Fe

Pyridine FTIR Analysis
Pyridine, ammonia and acetonitrile can be used to determine the Brønsted and Lewis acid sites of the catalysts. In this work, pyridine was used as molecular probe and it shows a clear distinction between the Brønsted and Lewis acid sites. Moreover, the kinetic diameter of pyridine is 0.57 nm which is lower than the 2.1-5.7 nm pore size of the catalysts [36]. Catalysts of high Brønsted/Lewis acidity ratio favours cracking and is also not selective for dehydrogenation [37]. Cracking is desired for hydroprocessing of oleic acid for production of jet-fuel range hydrocarbons and dehydrogenation is undesirable. Pyridine FTIR spectra and Brønsted/Lewis acid sites ratio of Fe (3)

Catalyst Evaluation
The products obtained from the hydroprocessing reaction were analyzed based on oleic acid conversion, yield and selectivity of jet-fuel range hydrocarbons. The results obtained from the gas chromatography (GC) analysis show that reaction time, temperature and catalysts have significant effects on the conversion of oleic acid, yield and selectivity of the jet-fuel range hydrocarbons. The error % for all the result was within ± 5%. Figure 7 shows the results obtained from the evaluation of Cu(5)/SiO2-Al2O3, Cu(10)/SiO2-Al2O3, Cu(13)/SiO2-Al2O3 and Cu(15)/SiO2-Al2O3 catalysts at 340 °C, 2.07 MPa hydrogen pressure and 5% catalyst/feed ratio. The effects of reaction times (2-10 hours) on the conversion of oleic acid is shown in Figure 7. The conversion of oleic acid increases with time for all the four catalysts. The highest oleic acid conversion obtained was 78.4% at 10 hours from the evaluation of Cu(13)/SiO2-Al2O3 catalyst. The effects of reaction time (2-10 hours) on the selectivity of jet-fuel range hydrocarbons are shown in Figure 7. The highest selectivity of jet-fuel range hydrocarbons obtained was 41.9% respectively at 6 hours. Unlike conversion of oleic acid, which increases with time, the selectivity of jet-fuel range hydrocarbons initially increases and later decreases with reaction time due to subsequent cracking of the jet-fuel range hydrocarbons to lighter hydrocarbons shown in Table S1. Oleic acid consists of macromolecules requiring catalyst of high pore size for easy internal diffusion. Cu(13)/SiO2-Al2O3 performs better than the other three monometallic catalysts due to its high pore diameter (5.3 nm), which implies high accessibility of oleic acid and hydrogen to the active site (copper) of the catalyst.

Catalyst Evaluation
The products obtained from the hydroprocessing reaction were analyzed based on oleic acid conversion, yield and selectivity of jet-fuel range hydrocarbons. The results obtained from the gas chromatography (GC) analysis show that reaction time, temperature and catalysts have significant effects on the conversion of oleic acid, yield and selectivity of the jet-fuel range hydrocarbons. The error % for all the result was within ± 5%. Figure 7 shows the results obtained from the evaluation of Cu (5) Figure 7. The highest selectivity of jet-fuel range hydrocarbons obtained was 41.9% respectively at 6 hours. Unlike conversion of oleic acid, which increases with time, the selectivity of jet-fuel range hydrocarbons initially increases and later decreases with reaction time due to subsequent cracking of the jet-fuel range hydrocarbons to lighter hydrocarbons shown in Table S1. Oleic acid consists of macromolecules requiring catalyst of high pore size for easy internal diffusion. Cu(13)/SiO 2 -Al 2 O 3 performs better than the other three monometallic catalysts due to its high pore diameter (5.3 nm), which implies high accessibility of oleic acid and hydrogen to the active site (copper) of the catalyst. The effects of reaction time (2-10 hours) on oleic acid conversion and selectivity of jet-fuel range hydrocarbons over the FeCu/SiO2-Al2O3 catalysts are shown in Figure 8. The conversion of oleic acid increases with time for all the catalysts. The highest oleic acid conversion obtained was 98% at 10 hours from the evaluation of Fe(3)-Cu(13)/SiO2-Al2O3 catalyst. The highest selectivity of jet-fuel range hydrocarbons obtained was 53.8% at 10 hours. The better performance of Fe(3)-Cu(13)/SiO2-Al2O3 catalyst is due to its smaller crystallite size and high dispersion of copper and iron metals and high reducibility of metals as compared to the other three catalysts.       The highest yield and selectivity of jet fuel hydrocarbons were recorded for Fe(3)-Cu(13)/ SiO 2 -Al 2 O 3 catalyst at 300 • C as shown in Figure 11 and Table 5. The total number of surface atoms of Cu and Fe per the total number of atoms present in the catalyst increases with surface area. Catalysts of high Brønsted/Lewis acid site ratio favours cracking, while oligomerization and dehydrogenation are favoured by catalysts of low Brønsted/Lewis acid sites ratio [37]. The internal diffusion calculation was carried out using the Weisz-Prater criterion [38]. The Weisz-Prater parameter for this reaction was 3.6 × 10 −7 , which is much less than 1 indicating that the internal diffusion in catalyst particles is absent. The experimental data show that with reaction time, more lighter hydrocarbons (C 5 -C 7 ) were produced from jet-fuel range hydrocarbons (C 8 -C 16 ) due to deep and mild cracking. This may be due to acidic nature of the catalysts used in this study. Hydroprocessing reactions of fatty acids, triglycerides and vegetable oils require catalysts of mild Brønsted acid sites to produce jet-fuel range hydrocarbons. Catalysts of high Brønsted sites have higher tendency of producing hydrocarbons that are lighter than the jet-fuel range hydrocarbons [8].  Table S3. The Fe(3)-Cu(13)/SiO 2 -Al 2 O 3 catalyst is the most productive catalyst, with 1.0 g jet fuel/g catalyst/h and 2.6 g jet fuel/m 2 metals surface area/g catalyst. The Fe(3)-Cu(13)/SiO 2 -Al 2 O 3 catalyst is the most promising when the entire temperature range(300-340 • C) is considered. This can be attributed to the relatively low Brønsted/Lewis acid sites ratio [8], high Cu and Fe metals dispersion, high pore volume, specific surface area of the Fe(3)-Cu(13)/SiO 2 -Al 2 O 3 catalyst and high surface composition of oxophilic iron metal observed from XPS fitting.

Support Preparation
HZSM support (SiO 2 /Al 2 O 3 : 23) was prepared by exchanging ZSM-5 with a 1.0 M ammonium nitrate solution at 100 • C for 3 h followed by calcination in air at 550 • C for 4 h [39]. Two commercial supports (amorphous silica alumina and ZSM-5) were used alongside with the synthesized HZSM.

ICP-OES
The mass compositions of copper and iron in Fe(3)-Cu(13)/SiO 2 -Al 2 O 3, Fe(3)-Cu(13)/ZSM-5 and Fe(3)-Cu(13)/HZSM-5 catalysts were evaluated using a concentrated mixture of HF/HNO 3 /HClO 3 to digest 0.125 g of each catalyst samples to dryness in a Teflon tube to analyze copper and also utilizing Ox automated fusion instrument to fuse the combination of Lithium metaborate and Lithium tetraborate mixture with 0.1 g of each catalyst samples in a graphite crucible for analyze iron. Dilute HNO 3 was then used to dissolve the dry residue and fused product obtained respectively from the copper and iron analyses and they were analyzed with Perkin Elmer ICP-OES (Optima 5300 DV) in the geoanalytical laboratory of the Saskatchewan Research Council.

N 2 -Adsorption/Desorption Measurement
Micrometrics ASAP 2020 instrument was used to characterize all the catalyst samples and their respective supports with the BET method. Each catalyst sample was degassed in a sealed tube in vacuum conditions at 250 • C for 5 h and evacuated until a static pressure of less than 1.33 Pa was obtained. Physisorption analysis was then carried out with N 2 at −196 • C. Three high-resolution regional scans were carried out using 0.05 eV steps with 20 eV pass energy. An accelerating voltage of 15,000 eV and an emission current of 0.015 A were used for the analysis.

FTIR Spectroscopy.
A JASCO FT-IR 4100 instrument was used to identify the functional groups of the all the synthesized catalyst samples and their respective supports. For analysis, 3 mg of sample was uniformly mixed with 0.4 g of KBr pellets. Qualitative analysis of the functional groups of the catalyst samples were obtained with 32 scans of 4 cm −1 nominal resolution. The IR spectra of pelletized samples were later recorded in transmission mode in the wavenumber range of 400-1400 cm −1 .

CO Chemisorption
The metal dispersion and crystallite size of Fe(3)-Cu(13)/SiO 2 -Al 2 O 3, Fe(3)-Cu(13)/ZSM-5 and Fe(3)-Cu(13)/HZSM-5 catalyst samples were measured using the Micrometrics ASAP 2020 chemisorption system. The catalyst samples were heated to 350 • C at 10 • C/min ramp rate in the presence of H 2 . They were then held for 2 h and later cooled down to 35 • C and evaluated to a static pressure below 1.3 × 10 −5 N/m 2 . Pulses of CO were passed over the evacuated sample and the total CO uptake was measured at 35 • C. Stoichiometric factor of 0.5 mole of CO per metal atom was used for copper and iron. 3 KPa using Micrometrics Auto Chem II 2920 analyzer. 10% H 2 /Ar was circulated to 0.05 g of each sample in a steel tube at 50 cm 3 /min and the temperature was increased to 850 • C from ambient temperature at 10 • C/min. As the temperature increases, the reaction of the catalyst and hydrogen gas proceeds to produce water vapour, which was trapped through a cold trap by outlet stream circulation. The exit gas stream was channeled via a calibrated thermal conductivity detector (TCD) for the detection of varying H 2 concentrations due to catalyst reduction.

Pyridine FTIR
The FTIR technique was utilized to study the nature of acid sites of Fe(3)-Cu(13)/SiO 2 -Al 2 O 3, Fe(3)-Cu(13)/ZSM-5 and Fe(3)-Cu(13)/HZSM-5 catalyst samples and their respective supports using a wavenumber region of pyridine (1400-1700 cm −1 ). A sample cylindrical cup in a Spectrotech diffuse reflectance in situ cell equipped with a thermocouple and zinc selenide windows was loaded with 0.01 g of each catalyst sample. These three catalyst samples and their respective supports were pretreated at 350 • C in order to remove any adsorbed water on the catalyst surface. Pyridine vapor was then passed over each catalyst sample at 100 • C for 1 hour to obtain pyridine chemisorbed samples. After adsorption of pyridine, nitrogen gas was used for the stabilization of the catalyst samples at 100 • C for 30 min with a ramping rate of 5 • C/min, then allowed to cool to ambient temperature. The samples were analyzed with a JASCO FT-IR 4100 instrument in the wavenumber range of 1400-1700 cm −1 and their respective IR spectra were recorded. Brønsted/Lewis acid sites ratio of all the three catalyst samples were calculated using Equation (5): where, C B C L = ratio of concentration of Bronsted and Lewis acid sites. IMEC(B) and IMEC(L) are integrated molar extinction coefficients (cm/µmol) of Brønsted and Lewis acid sites, respectively. IT(B) and IT(L) are integrated transmittances of Brønsted and Lewis acid sites, respectively [40,41].

Catalyst Evaluation
The catalytic reactions were carried out in a Parr stirred batch reactor. It is made in a bench top with moveable vessel mounting style. The capacity of the reactor vessel is 300 mL, with dimension of 2.5 inches diameter and 4 inches depth and the reactor is connected to a Parr 4848 reactor controller. The catalyst samples were evaluated in this Parr batch reactor. Two g of each of the catalyst samples and 40 g of oleic acid were placed in the reactor and hydrogen gas was used to pressurize the reactor to 2.07 MPa. Cu/SiO 2 -Al 2 O 3 and FeCu/SiO 2 -Al 2 O 3 catalysts were evaluated at 340 • C. The temperatures of the reaction involving support optimization studies were set at 300, 320 and 340 • C. The impeller speed and reaction time were 500 rpm and 10 h, respectively. The liquid product samples were collected at 2 h interval, filtered and diluted using chloroform as the diluent. The solution of liquid product samples was analyzed with GC (Agilent 7890A) equipped with a flame ionization detector (FID). A 30 m long DB-5 capillary column with 0.25 mm inner diameter was used. The temperature of the oven was programmed to start from 40 • C for 2 min and increased to 280 • C at 10 • C/min ramping rate with a 5 min final hold time. One µL of each product sample was injected with a split ratio of 10:1 into the column. C 6 -C 20 aliphatic hydrocarbons were used as external standard to quantify the liquid hydrocarbons produced. The gaseous products were analyzed using an online GC equipped with FID and catalyst performance was evaluated based on oleic acid conversion and jet-fuel range hydrocarbons (C 8 -C 16 ) selectivity as given below.
Oleic acid conversion (%) = amount of oleic acid reacted amount of oleic acid initially taken × 100 Selectivity of jet − fuel range hydrocarbons (%) = amount of jet − fuel range hydrocarbons amount of products formed × 100 (4) Yield of jet − fuel range hydrocarbons (%) = amount of jet − fuel range hydrocarbons amount of oleic acid initially taken × 100 (5)

Conclusions
In summary, copper metal with optimized loading on silica alumina support was suitable for hydroprocessing of oleic acid for production of jet-fuel range hydrocarbons. The best monometallic catalyst performance with 41.9% selectivity of jet-fuel range hydrocarbons (C 8 -C 16 ) was achieved at 340 • C, 2.07 MPa H 2 pressure and 6 hours reaction time over the catalyst with the largest pore size of 5.3 nm (Cu(13)/SiO 2 -Al 2 O 3 ).
Optimization studies of iron promotional effects for hydroprocessing of oleic acid for production of jet-fuel range hydrocarbons on the Cu(13)/SiO 2 -Al 2 O 3 catalyst showed more promising result in comparison with the monometallic copper catalysts due to effect of iron loading in lowering metal crystallite size indicating increase in metal dispersion. The best catalyst performance with 51.8% yield and 53.8% selectivity of jet-fuel range hydrocarbons was achieved over the iron-promoted copper catalyst with the lowest crystallite size (Fe (3) Support optimization studies on HZSM-5, ZSM-5 and SiO 2 -Al 2 O 3 supports reveal that Fe(3)-Cu(13)/ SiO 2 -Al 2 O 3 catalyst gives the best catalyst performance with 59.5% yield and 73.6% selectivity of jet-fuel range hydrocarbons. This promising performance was attributed to its large pore diameter, large pore volume and large surface area; low crystallite size and weak metal-support interaction from H 2 -TPR analysis, indicating, high metal dispersion from CO chemisorption analysis, high oxophilic iron content from XPS fitting and mild Brønsted acid sites from pyridine FTIR analysis.  Table S1: Selectivity of lighter hydrocarbons at t: 8 h; T: 300 • C, and P H2 : 2.07 MPa H 2 pressure. Table S2: Selectivity of C 8 -C 16 hydrocarbons at t: 8 h; T: 300 • C, and P H2 : 2.07 MPa H 2 pressure. Table S3: Catalysts productivity towards C 8 -C 16