All chemicals and solvents were commercially available and used as received. Thiophene (Th), benzothiophene (BT), dibenzothiophene (DBT), n-heptane, hydrogen peroxide (H2O2, 30 vol.%), acetic acid (CH3COOH), acetonitrile (MeCN), chitosan (low molecular weight with a deacetylation degree of 75–85%), imidazole (C3H4N2), phosphotungstic acid (H3PW12O40.nH2O), and hydrochloric acid (HCl) were purchased from Sigma–Aldrich. Typical gasoline with the following specifications was used: density of 0.7989 g mL-1 at 15 °C and total sulfur content of 0.4980 wt%. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essaySynthesis of IMID-PTAThe organic-inorganic hybrid [C3H4N2]3[PW12O40] was synthesized according to the method reported by Zonoz et al.24 0.03 g of PTA was dissolved in 1 mL of distilled water. Then, a solution of 0.08 g of IMID in 5 mL of HCl (1 M) was slowly added to the stirred PTA solution. The solution was stirred for 2 hours at room temperature. The obtained product (called IMID-PTA) was filtered, washed with hot distilled water and then dried in an oven at 80 °C for 2 hours. Immobilization of IMID-PTA on CSIn a typical synthesis, 0.50 g of CS was dissolved in a 2% CH3COOH solution to obtain a clear solution. Then, 0.10 g of dried IMID-PTA powder was added to the CS solution and sonicated using ultrasonic bath for 10 min at room temperature. The fully dispersed solution was precipitated by centrifugation (2000 rpm, 40 minutes). Finally, the formed precipitate (IMID-PTA@CS) was separated by filtration, washed several times with distilled water, and dried in an oven at 80 °C for 2 h. ODS process of model fuel In a typical experimental procedure, a certain amount of heterocyclic sulfur compounds (HSCs) such as Th, BT and DBT were dissolved in n-heptane as model fuel to evaluate the catalytic performance of IMID-PTA@ nanocatalyst CS in the ODS Process. The sulfur concentration of each HSC was 500 ppmw. The water bath was initially heated to a temperature between 25 and 40 °C. Then, 50 mL of model fuel sample in a closed round-bottom flask equipped with magnetic stirrer was heated to the reaction temperature. Next, 3 mL of CH3COOH:H2O2 in a volume ratio of 1:2 and various amounts of prepared nanocatalyst from 0.02 to 0.12 g were slowly added into the reaction vessel. The ODS process was continued under stirring conditions (500 rpm). After 1 hour, the above mixture was cooled to room temperature and 10 mL of MeCN was added to extract the oxidized HSCs. The formed immiscible liquids (n-heptane and aqueous phases) were separated using a separating funnel and decantation technique. The synthesized nanocatalyst (IMID-PTA@CS) was regenerated from the reaction system using simple filtration and reused in the next run. The total sulfur concentration after oxidation treatment was determined using X-ray fluorescence spectrometer according to ASTM D4294 and D3227. ODS Process of Gasoline Fuel In the same way as the ODS of HSCs, after heating the water bath, 50 mL of gasoline fuel was added to the round-bottom flask and its temperature maintained at 35 °C throughout the experiment. Subsequently, 3 mL of CH3COOH:H2O2 and 0.1 g of IMID-PTA@CS were added to the vessel. The mixture was stirred vigorously using a magnetic stirrer for 1 hour. Once the oxidation process was complete, the flask was cooled to room temperature and then 10 mL ofMeCN polar organic extraction solvent to extract polar oxidized sulfur compounds. In the separation phase the oily phase was separated by decantation. The total contents of sulfur and mercaptans in gasoline before and after the ODS test were determined using X-ray fluorescence. The ODS efficiency was expressed by the following eq. 1, where C0 and C correspond respectively to the initial concentration and the final concentration of the total sulfur content in the gasoline: Fourier characterization methodsTransformed infrared spectroscopy (FTIR) studies were performed by Thermo-Nicolet-iS 10 spectrometer, using KBr disks in the range 400–4000 cm−1. X-ray powder diffraction (XRD) analysis was collected between 2θ of 10 and 80° at room temperature on a Bruker D8 advanced powder X-ray diffractometer with a Cu Kα radiation source (λ = 0.154 nm) . Surface morphologies were examined by scanning electron microscopy (SEM) using LEO 1455 VP. 31P nuclear magnetic resonance (NMR) spectra were recorded on Bruker Ultra Shield 250 MHz. The sonication process was realized by Bandelin Sonorex Digitec ultrasonic bath. The total sulfur and mercaptan contents in gasoline before and after treatment were determined using X-ray fluorescence with a TANAKA RX-360 SH X-ray fluorescence spectrometer. Results and discussion Material characterizations To confirm the incorporation of materials, FT-IR spectra were recorded on the PTA, IMID, CS, modified IMID-PTA and pure IMID-PTA@CS hybrid nanocatalyst. As shown in Figure 1a, the unique characteristic peaks at 776, 895, 955, and 1080 cm-1 are caused by Keggin-type [PW12O40] 3- anion stretching modes involving W–Oc–W edge sharing, corner - they share W–Ob–W, terminal W=Ot and P−O bond respectively.25 The absorption bands in the IMID spectrum are present at 619 cm-1 and 657 cm-1 assigned to C2–N1–C5 bending vibrations (Figure 1b). Furthermore, the peaks around 1447 cm-1 are attributed to the stretching vibrations of C–N, while the vibration modes of the imidazole ring can be observed in the spectral areas of 1540-1573 cm-1.24 As shown in the spectrum of As the synthesized IMID-PTA ring, the intense absorption bands from 767 cm−1 to 1081 cm−1 are clearly observed due to the characteristic vibrations of polyoxo anions (Figure 1c). According to Figure 2b, the appearance of peaks at 987, 1592, and 1670 cm-1 indicated the vibrations of C–O–C, H–N–H, and C=O in the glycosidic structure of CS polymer, respectively. The investigation spectrum of the IMID-PTA@CS composite is shown in Figure 2c. Compared to bulk materials, the observed shifts of the nanocatalyst peak positions are observed. The existence peaks in the region of 700–1100 cm-1 demonstrated that PTA retained its Keggin structure after immobilization on CS. The characteristic peaks of CS from 987 to 1670 cm-1 cannot be found in Figure 2c, which are superimposed on the absorption bands of IMID. Meanwhile, the peaks at 2850, 2926 and 3331 cm-1 are revealed by the stretching vibrations of alkyl, amine and hydroxyl groups of CS. It should also be emphasized that the branched P–O vibration at 1064 cm-1 confirmed the strong interactions between the anionic PTA and the cationic IMID. The materials were characterized by XRD technique in the scanning range 10° ≤ 2θ ≤ 80°. As shown in Figure 3a, the XRD pattern of the bulk PTA shows the sharp and narrow unique diffraction peaks at the 2θ values ​​of 17–23° and 26–30°. CS with semicrystalline nature shows refraction at 19.9˚ (Figure 3c).26 The diffraction peaks of IMID-PTA are shown in Figure 3d, which shows the presence of characteristic peaks.