Dealumination Effect on ZSM-5 as a Bimetal Fe-Co Support for The Oxidative Desulfurization Process Catalyst

Abstract


INTRODUCTION
The combustion of burning fuel containing sulfur will cause the formation of sulfur oxide (SOx) which is toxic, corrosive, and dangerous for the environment.The European Union issued strict environmental regulations on refinery operations to produce fuel with the lowest sulfur content 1,2 .
Fuel desulfurization is increasingly necessary today, not only because of increasing concerns regarding environmental and legal requirements but also because very low sulfur fuels are a key requirement in fuel cell applications.Currently, fuel sulfur content requirements are increasingly stringent to achieve net zero emissions (NZE), including Indonesia 3,4 .Refineries around the world continue to develop new processes to reduce sulfur levels in fuel.
Nowadays, it is widely known that oxidative desulfurization (ODS) is considered a new technology to achieve ultra-low desulfurization.The biggest advantage of the ODS process is that the process runs at lower reaction temperatures and pressures compared to the hydrodesulfurization process which has been used and is considered a conventional desulfurization process 5,6 .
However, the ODS process has obstacles, namely, (i) the steric barrier of the large organosulfur thiophene molecule and its derivatives, (ii) the resonant nature of organosulfur, (iii) the use of non-polar oxidants which cause biphasic hindrance in the desulfurization process of organosulfur in fuel.which is non-polar (iv) the process of separating sulfone resulting from the organosulfur ODS process in fuel which is polar (v) the use of excess oxidant from stoichiometry which disrupts the reaction balance and quality of the fuel due to the presence of other reaction products besides sulfone 5 .
Zeolite or ZSM-5 has attracted significant attention for the ODS process due to its high selectivity properties and adsorption capabilities.However, the pore size of ZSM-5 is dominated by 5Å, which limits its effectiveness in addressing steric hindrance problems related to large organosulfur molecules.Studies on the exploration aspect of zeolite pore engineering techniques continue to be carried out to enhance the efficiency of ODS processes [6][7][8] .
Wang et al carried out pore engineering by synthesizing amphiphilic hierarchical ZSM-5 using the bottom-up method, namely a synthetic method from the start where the hierarchical pore engineering process with a high Si/Al ratio was carried out during the synthesis process and impregnated with Ti 8 .Jafarinasab et.al impregnated Co into the mesopore imidazolate framework of zeolite-67 to form CoZIF-67, which was then modified again by pore engineering combined with HPMo encapsulation to become CoZIF-67 9,10 .Dashtpeyma et al modified the hierarchical clinoptilolite zeolite pores using a delamination-desilication modification method impregnated with BiVO4-CuO 11 .Yao et.al carried out pore hierarchy engineering on meso-TS-1 zeolite treated with hydrophobization created by sequential pre-treatment, mesoporous-assisted DGC and hydroxyl radical post-treatment by increasing the amount of TIO6 carried by the zeolite 12 .Kargar et.al synthesized the magnetic catalyst Fe3O4/ZIF-8/TiO2 for the ODS process.The Fe catalyst's magnetic properties simplify the separation of ODS results.Nevertheless, the process still necessitates agent mass transfer and takes longer compared to the widely reported ODS process, which only takes 6 hours 13 .Zhang et al synthesized hierarchical pores with the help of amide into TS-1 zeolite and formed the active site Ti (OH2)2(OH)2(OSi)2 6 .However, most still use mass transfer agents such as acetonitrile to overcome the biphasic hindrance and use excess oxidant from stoichiometry resulting in large byproducts.The H2O2 oxidant produces water, thereby increasing the water ratio in the fuel, while the TBHP oxidant, produces tertiary butanol which will reduce the quality of the fuel 5, 14 .
Several studies are concerned with exploring catalysts that can overcome problems in the ODS process and increase its effectiveness in terms of ease of synthesis, selectivity, and performance.The desired catalyst has mesopore-dominated hierarchical pores to facilitate the oxidation reaction of Dibenzothiophene (DBT) which has a large molecular size, around 9Å, and better reaction transport 15,16 .In addition, the hydrophobic nature of the catalyst helps overcome biphasic hindrance 12,17 .From a review of reported ODS research, Fe and Co are currently an attractive combination of transition metals in ODS processes [18][19][20][21] .Nie et.al discovered that combining transition metals Fe and Co in a 5:2 ratio yields the most optimal mixture.This combination generates a potent peroxidase enzyme, which efficiently breaks down H2O2, akin to a Fentonlike reaction.This reaction results in the creation of hydroxyl radicals, which can effectively oxidize organosulfur compounds.It is that this type of reaction is rarely reported 22 .
Therefore, we propose a hierarchical strategy by engineering the ZSM-5 catalyst as a support for the Fe-Co ferromagnetic transition metal in a 2:1 ratio, which can create the Fe-Co/ZSM-5Hierarchy catalyst.This catalyst contains mainly mesopores and is hydrophobic, resulting in enhanced performance.In this study, we also evaluated the catalyst effectiveness on a DBT model diesel fuel in a solution of long-chain hydrocarbon compound, n-hexadecane, a unique approach that has not been previously reported in ODS process catalyst tests.

Catalyst Preparation
NaZSM-5 Activation 500 mL of 1 M NH4Cl solution was added to 40 grams of NaZSM-5, which was then refluxed for 5 h at a temperature of 900 o C. Afterward, NaZSM-5 was washed and filtered with distilled water 4 times until it was free of Cl -, which was tested with AgNO3.Then it was filtered and put in the oven set at 65 o C for 24 h.Next, it was calcined in a furnace at a temperature of 450 o C for 3 h 23,24 .

Synthesis of HZSM-5 Hierarchy
HZSM-5 is the result of activation of NaZSM-5 which is then hierarchical by dealumination with 10 % HF added, then stirred until homogeneous for 30 min.Then filtered and washed with distilled water 3 times.Then steam treated with 1M NH4Cl solution for 5 h at 90 o C.After that, it was filtered and washed three times until it was free of Cl -, which was tested with an AgNO3 solution.Next, it is dried in an oven for 8 h at a temperature of 100 o C, then calcined in a furnace at a temperature of 550 o C for 3 h 25,26 .

Impregnation of ZSM-5
Following the dealumination of ZSM-5, the resultant material was wet impregnated with Fe-Co bimetal, with a 2:1 ratio of Fe to Co, at concentrations of 5% and 15%.The mixture was stirred for a period of three hours with the aid of a magnetic stirrer, after which it was subjected to an oven at a temperature of 50°C for a duration of 12 hours.Subsequently, it was calcined at a temperature of 450 °C for a period of 5 hours 27,28 .

Catalyst Characterization
The resulting catalyst was then characterized using an XRD (X-Ray Diffraction) instrument, Rigaku Miflex on CuKα Monochromatic Radiation Beam (1.5405 Å) to identify the structure and determine crystallinity, with a speed of 10 o /min and a range of 2θ 3-90 o , and a step width 0.02 o .Then the SAA (Surface Area Analyzer Quantacrome Nova 4200e) instrument with the BET (Brunauer Emmett-Teller) and BJH (Barret-Joiner-Halenda) methods to measure the N2 adsorption-desorption isotherm and determine the surface area, pore volume, and pore diameter.Nitrogen adsorption and desorption isotherms were measured at 77 K in the relative pressure range of 0.05-0.99.X-ray fluorescence analysis (ED-XRF type) using Rigaku NexCG to determine the amount of metal in the catalyst.

Catalytic Oxidative Desulfurization of Model Oil
Put the catalyst into a three-neck flask, then add 10 mL of model oil, namely DBT in n-Hexadecane with a concentration of 500 ppm, and add 30 wt% H2O2 oxidant.The process is carried out with varied conditions to find optimum operating conditions.After the ODS process, the results are separated by decantation.The search for the conditions of the desulfurization oxidation process with the Fe-Co(15)/ZSM-5 catalyst was carried out on DBT in n-hexadecane as a model oil at a concentration of 500 ppm for 10ml.This is done by varying the amount of catalyst according to the number of catalysts used in 10 mL of model oil, that is 0.05, 0.1, 0.2, 0.3 g, and varying the ratio of H2O2 as oxidant concentration used to DBT in model oil (O/ S); 1, 2, 4 .7,temperature variations 35, 45, 60 o C, and time variations 30, 45, 60 min.The result that provides optimal DBT conversion is taken as the operating condition.
The amount of converted sulfur was determined using a UV-Vis instrument that had been calibrated for absorbance and a concentration geometric series search was carried out.Measurements were carried out with a Uv-Vis Spectrophotometer -Thermo Scientific Genesys 10 S spectrum at a wavelength of 320 nm.Next, the removal of sulfur compounds is calculated as a DBT conversion with the equation 1 [29][30][31] : Where: C0 = initial concentration of DBT Ci = final concentration of DBT Then the catalyst TOF (Turnover Frequency) is calculated in the oxidative desulfurization catalytic reaction with the equation 2 6 : Where n(sulfide)initial is the initial mole of sulfide, and n(Fe-Co) is the mole of Fe-Co species in the catalyst.

Catalyst Characterization
The XRD pattern characterization confirmed the structural characteristics of Fe-Co/ZSM5-Hierarchy, as shown in Figure 1.Each pattern displays the typical Type MFI zeolite structure peak at the 2θ point at 8 o -25 o 32,33 .Which one, XRD instrument analysis matched the XRD pattern to ICDD (PDF2.DAT), with NaZSM-5, HZSM-5, and HZSM-5Hierarchy matching DB card number 00-037-0361, and Fe-Co(5)/ZSM-5Hierarchy corresponding to DB card number 00-039-0161, phase name ZSM-5(Fe).Additionally, Fe-Co(15)/ZSM-5Hierarchy matched DB card number 00-048-0134 with the phase name ZSM-8.While there was no significant change in peak position, there was a clear change in peak height, indicating the influence of each treatment (activation, dealumination, and impregnation treatments) given.Changes in peak height can be attributed to a decrease in atoms in the crystal structure, which can cause an increase in crystal size, while a decrease in peak height can be caused by an increase in atoms in the crystal structure or a decrease in crystal size 24,28,34 .
It appears that the desired catalyst synthesis was successful as there was a noticeable change in the height of the diffraction peak from Na-ZSM-5 to H-ZSM-5 after the Na atom was removed.At the highest point of 2θ at 23 o , there was a significant increase in 2θ at 8 o .After dealumination, there was a notable increase in the peak, especially visible at the peak height of 2θ at 8 o due to the loss of Al atoms from the dealumination process with hydrofluoric acid (HF).The high peak at 2θ at 8 o suggests the presence of a mesoporous 35,36 .Moreover, when HZSM-5Hierarchy was impregnated with bimetal Fe-Co, there was a decrease in peak height, indicating that the loading of metal impregnated can affect the crystal size and crystallinity 37,38 .Metal impregnation generally decreases crystallinity and crystal size, but the type and amount of metal impregnated affects the strength.The heat given to HZSM-5 which has embedded metal, causes atomic shifts, convergence, or divergence of atoms freely.This can cause the crystal lattice to vibrate and probably phase changes to occur 39,40 .As previously explained, the results of the XRD instrument analysis stated that the Fe-Co(5)/ZSM-5Hierarchy catalyst matches the ZSM-5 (Fe) phase while the Fe-Co(15)/ZSM-5Hierarchy matches the ZSM-8 phase.
The XRD test results shown in Table 1 show that HZSM-5 impregnated with 5% bimetal Fe-Co (Fe-Co(5)/ZSM-5Hierarchy) has the smallest crystal size.A sample with high crystallinity will produce a diffraction pattern with intense and sharp peaks.Conversely, an amorphous material will not have any peaks in its diffraction pattern.Table 1 illustrates the high crystallinity of the HZSM-5 hierarchy, and Figure 1 displays the highest peak at peak 2θ at 23 o .The size of the crystals is determined by examining the main peaks in the diffraction pattern obtained from the XRD instrument test results.Using an approach Debye Scherrer's equation is formulated :

𝐷 = K λ 𝛽 cos 𝜃
Where: D = Crystal size B = FWHM value θ = Bragg angle  = wavelength of X-ray light.K = constant "Shape Factor" (0.8-1) The XRF test results in Table 2 show that more Fe-Co is embedded in the Fe-Co(15)/ZSM-5Hierarchy, but the Fe: Co ratio is greater in the Fe-Co(5)/ZSM-5Hierarchy catalyst.From Table 2, it can also be seen that the Si/Al ratio values are almost the same for the catalysts tested for the bimetal Fe-Co(5) and Fe-Co(15) embedded catalysts.It can be said that the catalyst used is close to homogeneous 41 .The dealumination process causes a high Si/Al ratio which makes the catalyst hydrophobic 7,42 .It is known that the Si species that influence the catalyst properties lead to hydrophobicity 43 .
The BET analysis shows the N2 adsorption and desorption isotherms shown in Figure 2 with its textural properties summarized in Table 3.According to the IUPAC classification, the sample shows that NaZSM-5 is a type I adsorption isotherm, where this type is usually obtained from adsorbents with micropores of less than 2nm and a small surface area 44,45 .As seen from Table 3, NaZSM-5 has the smallest surface area, namely 31.87 m 2 /g.Then HZSM-5 has a pattern that is almost the same as NaZSM-5, with type I isotherm, but HZSM-5 has a hysteresis loop close to type IV.This is due to a shift in the position of Na which is replaced by H upon ZSM-5 activation, so that there is capillary condensation and evaporation at different pressures which causes a hysteresis loop.Meanwhile, for the HZSM-5 Hierarchy, Fe-Co(5)/ZSM-5 Hierarchy, and Fe-Co(15)/ZSM-5 Hierarchy catalysts, the type of catalyst adsorption isotherm is type IV, and the hysteresis loop is type IV 44 .Figure 2 also shows that The catalyst has pores or is a porous material with a relatively high absorption amount at P/Po ~ 0,933.37.N2 adsorption on H-ZSM-5Hierarchy and Fe-Co(15)/ZSM-5Hierarchy is significantly high at P/Po ~0.9 which reflects that the catalyst has a lot of mesopore structure 46 .
Embedded metals to zeolites can increase surface area, increase catalytic active sites, and improve accessibility to reactants.However, the magnitude of this effect depends on several factors, including the type of metal used and the impregnation technique.Even distribution of the impregnated metal on the support is very important because uneven distribution can cause pore blockage and agglomeration.Supports with high porosity or dominated by mesopores are more likely to show an increase in surface area after metal impregnation 39,[47][48][49][50][51] .
Table 3 shows that the NaZSM-5 catalyst activation process can increase the surface area of the catalyst from 31.87 m 2 /g to 150.85 m 2 /g, but does not change the average pore radius.The activation process opens due to ion exchange between NH4 + ions and Na cations in Na-ZSM-5.This activation process is carried out by heating using NH4 + , where on heating it will become NH3 vapor and allow H + to bind to ZSM-5 to form H-ZSM-5.The loss of Na cations produces more templates or pores thereby increasing catalytic activity 23,32 .In contrast to dealumination, the dealumination process not only increases the catalyst surface area to 166 m 2 /g in HZSM-5 Hierarchy but also increases the pore radius to 1,591 and clarifies the micro, meso, and macro pore levels with a high number of mesopores, so it can be said to be a hierarchical process succeed.The dealumination process to form a pore hierarchy is said to be successful when there are several levels of pores, signs of eliminating micropores 25,52 .The dealumination process collapses the structure of ZSM-5 and extracts Al species from the framework, thereby opening the pores.Dealumination is carried out by steam treatment using NH4Cl to keep the main structure from collapsing but can open the pores with HF which extracts Al, this steam process helps form hydroxyl so that Si can replace Al's position in the framework optimally.Extracted Al from the skeleton 25,26 .Table 3 also shows that the surface area of the catalyst is maintained and even tends to increase after impregnation, namely to 191.18 m 2 /g on Fe-Co(5)/HZSM-5Hierarchy, and 168.94 on Fe-Co(15)/HZSM-5Hierarchy, while maintaining the Pore hierarchy.The reduced surface area in the Fe-Co(15)/HZSM-5 Hierarchy is probably caused by the impregnation process, most of the surface is covered or pore blockage by the high bimetal concentration, thereby reducing the pore surface area.The catalyst pore size distribution in Figure 3 shows that it is in the range of 1.4 to 60 nm with larger mesopores, namely r > 1 nm or d > 2 nm.
The results of the analysis of catalyst characteristics can be said to have succeeded in designing the mesopore-dominated Fe-Co/HZSM-5Hierarchy catalyst, which is expected to overcome the steric barrier of problems in the desulfurization process so far, because the size of the organosulfur molecules in the fuel is large, especially the DBT 10,53 .Then the hydrophobic nature of this catalyst can overcome the biphasic hindrance of the difference in polar poles of the ODS reaction 7,46 .The overcoming of steric barrier and biphasic hindrances causes the use of oxidant as O/S following the stoichiometric amount of 2 mol so that it does not cause interference from the formation of large amounts of aqueous from the decomposition of oxidant, thus increasing the effectiveness of the catalyst 5,54.Pore radius average, micro, meso, and macro pore volume were determined by the BJH adsorption-desorption curve.

Catalytic Oxidative Desulfurization of Model Oil Looking for ODS operating conditions
Looking for ODS operating conditions on model oil with the Fe-Co(15)/ZSM-5Hierarchy catalyst because it is considered to have a larger amount of Fe-Co, so it can produce enough hydroxyl to oxidize organosulfur properly so that large conversions can be obtained.look for operating conditions with a 10 ml oil model with variations in the amount of catalyst, oxidant ratio with DBT concentration in fuel [O/S], temperature variations, and time variations.Then the results of the optimum operating conditions obtained were applied to the Fe-Co(5)/ZSM-5Hierarchy, HZSM-5Hierarchy, HZSM-5, and NaZSM-5 catalysts.

Effect the amount of catalyst
The amount of catalysts here is the amount of catalysts used in the ODS process.Figure 4 shows a trend of significantly increasing conversion at a catalyst amount of 0.2 g and decreasing when the amount exceeds 0.2 g.This shows that catalysts play an important role in the ODS process.This means that at that dose, the catalyst offers a sufficient amount of active sites for high catalytic reactivity.If there are excess active sites, collisions with reactants will not be effective, resulting in a decrease in reaction yield.In addition, excess catalyst causes competing reactions to occur with active species and affects the reaction equilibrium, resulting in reduced catalyst activity 55,56 .

Effect of Oxidants (O/S)
The oxidant ratio refers to the proportion of oxidant utilized to the sulfur concentration present in the fuel.As illustrated in Figure 5, the highest conversion can be achieved when the O/S ratio is at 2. This indicates that the optimum conditions for the O/S ratio, as per stoichiometry, have been attained.Any addition of oxidant beyond stoichiometry has a negative effect since it significantly reduces conversions.The oxidant H2O2, used to oxidize DBT, produces water as a by-product.However, excess water can make it challenging for oxidant reactions to occur with species at the active site of the catalyst 6,7,55 .The type of catalyst has a significant impact on the ability of oxidants to oxidize.Impregnated Fe-Co aims to enhance the decomposition of H2O2 oxidants, thereby generating abundant molecular oxygen to ensure optimal organosulfur oxidation in fuel.Figure 5 demonstrates that the objective of Fe-Co impregnation is achieved by utilizing oxidants at stoichiometry O/S 2. Scheme 1 depicts the mechanism of bimetal Fe-Co decomposition of H2O2.

Effect of Temperature
The ODS process offers several appealing advantages, notably its ability to function under mild operating conditions that are considerably lower than traditional HDS processes 57 .During this process, temperature aids polar oxidants in penetrating the pores of the hydrophobic catalyst, which has been effectively dispersed within the non-polar model oil.This allows for reactions to take place effectively on the pore surface 7,8 .As depicted in Figure 6, DBT conversion rates steadily rise with increased temperature but begin to decline gradually beyond 45°C.This may be because H2O2 is prone to decomposition at high temperatures, leading to premature oxidant breakdown and subsequent disruption in the reaction equilibrium caused by the presence of excess oxidants.The outcome of the H2O2 decomposition reaction is determined by contact with the active site, which can generate other reactions that interfere with the oxidation reaction, ultimately resulting in a decreased DBT conversion 56 .

Effect of Time
Reaction time follows the reaction pattern and the nature of the reaction to factors that influence the reaction such as temperature, amount of reactant, and catalyst 6,58 .In this study, reaction times varied at 30, 45, and 60 min, and Figure 7 shows that the optimum reaction occurred at 45 min, which means the reaction rate was large at this time and decreased after passing the reaction equilibrium.Figure 7 shows that as time increases, the conversion decreases and it can be seen that the trend of the time-influence phenomenon is close to the temperature-influence trend.

ODS Catalytic Process
The Fe-Co/ZSM-5Hierarchy catalyst effectiveness test was carried out with model oil, namely DBT in Hexadecane with a concentration of 500 ppm.The ODS process was carried out under optimum conditions, namely at a temperature of 45 o C, with the amount of catalyst used in the process being 0.2 g, O/S 2, and a reaction time of 45 min.Figure 8 shows that engineering the pores into a hierarchy has a big influence on the ODS process, where it can be seen that the DBT conversion increases significantly.Then the increase continued to occur on the catalyst that had been embedded with bimetal Fe-Co, with the highest DBT conversion on the Fe-Co(5)/ZSM-5Hierarchy catalyst, with a TOF value of 205 h -1 (equation 2).Decreased DBT conversion on the Fe-Co(15)/ZSM-5Hierarchy catalyst with a TOF value of 157 h -1 .This means that Fe-Co(5)/ZSM-5Hierarchy is a promising catalyst and provides high reactivity for the ODS process with a sufficient number of active sites.It can also be said that high catalyst reactivity occurs in catalysts that have a higher Fe: Co active site ratio.
Measuring the TOF (turnover frequency) value is a determining parameter for catalyst performance.TOF is the number of moles of reactant converted to the desired product by each active site per hour.This is calculated from the reaction rate and the amount of active site metal (equation 2), which can be said to directly measure the reaction productivity and active site reactivity of the catalyst 6, 59 .TOF is a measure of the intrinsic activity of a catalyst which is an important parameter in catalyst science that functions to measure the number of reactions that can be carried out by one active site in a catalyst per certain unit of time.The TOF value is used to determine the efficiency and performance of catalysts in various reactions by providing an overview of the reaction speed at the molecular level at the active site of the catalyst.This is important to understand because TOF can provide insight into how quickly a catalyst can catalyze a particular reaction, which in turn can influence the efficiency of the overall catalysis process 6, 60 .This means that the Fe-Co/ZSM-5Hierarchy catalyst has great potential in the ODS process so it is interesting to continue to explore it to produce higher catalyst activity so that ultra-low desulfurization can be achieved.

This work
Table 4 shows the comparison of TOF values using similar ODS methods.It can be seen that the Fe-Co/ZSM-5Hierarchy catalyst has a higher TOF value in the DBT process on long-chain model oil, with the use of an oxidant according to its stoichiometry, without the addition of mass transfer agents or extractants.This means that the Fe-Co/ZSM-5 Hierarchy catalyst is a promising catalyst for the ODS process and is interesting to continue to explore.

Proposed Reaction mechanism
The proposed ODS mechanism presented in Figure 9 will demonstrate the catalytic role of Fe-Co/ZSM-5Hierarchy in the Dibenzothiophene ODS process.The ferromagnetic nature of Fe-Co bimetal will stop the organosulfur resonance in the fuel, thereby facilitating the electron transfer process in the ODS process 17,61 .The hydrophobic nature of the catalyst overcomes the biphasic barrier, thus facilitating the dispersion of the catalyst in the fuel and the entry of organosulfur into the catalyst pores to react with oxidants at their optimum temperature 7,8 .*OH radicals are real oxidants that oxidize S compounds to sulfoxides, and finally sulfones 56,62 .*OH radicals are produced from the decomposition of H2O2 as an oxidant which is produced in three ways in the decomposition process with bimetal Fe-Co which is shown in scheme 1.Firstly, bimetal Fe-Co donates electrons to H2O2 so that decomposition occurs which produces *OH radicals.Then hydrolysis occurs of the Fe 3+ and Co 3+ to become Fe 2+ and Co 2+ and *OOH radicals are produced at the same time.Next, the *OOH radical forms the *OH radical through a bimolecular self-reaction by releasing oxygen 20,63 .The redox cycles of Fe 3+ /Fe 2+ and Co 3+ /Co 2+ promote the In the end, the Fe-Co/HZSM-5Hierarchy returns to its original form, where the framework is porous and hydrophobic, causing the sulfones and water produced to be trapped by the framework so that the model oil is very easily separated by decantation 8 .This shows that the reaction easily occurs on the active site of Fe-Co/ZSM-5Hierarchy.In theory, it is known that the ODS reaction occurs in two stages, namely the sulfoxide formation stage followed by the formation of sulfone 64 .This is one of the reasons why sulfone oxidation is often less successful because the sulfoxide formation step is a nucleophilic event that requires electron transfer facilities from nucleophilic species 64,65 .In fact, in theory, the oxidation reaction of organosulfur compounds is an electrophilic substitution reaction that requires electrophile species.Here, Co 2+ /Co 3+ is responsible for facilitating the formation of sulfoxide very quickly by removing the hydrogen atom from the organosulfur group and replacing it with oxygen from the hydroxyl radical as a nucleophile species so that the sulfoxide formation reaction is easily passed 18,54,66 .
Then electrophilic substitution to form products occurs easily because of the presence of reactive oxygen as an electrophile species from the breakdown of *OOH which results from the decomposition of H2O2 by Fe-Co.HOO* is a hydroxyl peroxide radical, i.e. a molecule with one unpaired electron, so it is very reactive and the presence of Fe-Co allows it to participate in reactions that produce electrophilic oxygen 20,63,67,68 .

CONCLUSIONS
The Fe-Co/ZSM-5Hierarchy catalyst has been successfully obtained which is dominated by mesopores and has hydrophobic and environmentally friendly properties.The characteristics of the catalyst show that the hierarchical process using a top-down dealumination method with steam treatment under reflux conditions on the HZSM-5 catalyst support causes the catalyst to have multimodal pores dominated by mesopores with a high surface area so that it can overcome steric barrier in the Dibenzothiophene ODS process.Catalyst reactivity is characterized by the TOF value, where Fe-Co(5)/ZSM-5Hierarchy has the highest TOF value of 205 h -1 under mild operating conditions, namely 45 o C, for 45 min with oxidant at an O/S ratio according to stoichiometry, namely 2 and the amount of catalyst used is 0.2 g.Apart from that, the catalyst has a high Si/Al ratio, causing the catalyst to be hydrophobic, where this hydrophobic property can overcome the biphasic hindrance in the ODS DBT process on fuel, thereby increasing the effectiveness of the catalyst.

Figure 7 .Figure 8 .
Figure 7. Effect of time on the ODS of the process with the Fe-Co(15)/ZSM-5Hierarchy catalyst

1 .Figure 9 .
Scheme 1. Reaction mechanism of H2O2 decomposition by the active site of the Fe-Co/ZSM-5Hierarchy catalyst

Table 1 .
The

Table 2 .
Elemental composition in catalysts based on XRF analysis

Table 3 .
Physicochemical properties of the catalyst a Surface area and was determined by BET analysis.b,c,d,e

Table 4 .
Comparison of TOF dari proses ODS DBT from recent reports with various catalysts