Oxidative and Extractive Desulfurization of Fuel Oils Catalyzed by N-Carboxymethyl Pyridinium Acetate and N-Carboxyethyl Pyridinium Acetate Acidic Ionic Liquids: Experimental and Computational DFT Study

This study reports on the synthesis, characterization, and application of two acidic ionic liquids, namely, N-carboxymethylpyridinium acetate ([HO2CCH2Py][CH3CO2] or AIL1) and N-carboxyethylpyridinium acetate ([HO2C(CH2)2Py][CH3CO2] or AIL2), as both extractants and catalysts for the oxidative and extractive desulfurization (OEDS) of model fuel oils containing heteroaromatic sulfur compounds. The structural properties of the synthesized acidic ionic liquids (ILs) were confirmed by 1H NMR, 13C NMR, and FT-IR spectroscopic analysis. To optimize the performance of the acidic AILs in the desulfurization process, the effects of different parameters, such as H2O2 dosage, reaction time, and temperatures, were investigated. The experimental results showed that AIL1 has exceptionally high desulfurization-extraction rates, with values of 99.8%, 97.8%, and 95.4%, for DBT, BT, and 4,6-DMDBT, respectively, under the optimum conditions established. Under the same conditions, the desulfurization-extraction rates using AIL2 reached 91.6%, 87.3%, and 82.4%, respectively, for DBT, 4, 6-DMDBT, and BT. Both ionic liquids can be recycled up to 9 times without a significant decrease in their sulfur removal efficiencies. Furthermore, density functional theory (DFT) calculations were conducted to evaluate the electronic interaction energies (ΔIE) between the AILs with each of the sulfur-containing compounds and their putative oxidized products. The computational findings strongly supported the experimental outcomes.

Pyrolysis of Mixed Date Stones and Pistachio Shells: Identification of Bio-Oil and Utilization of Bio-Char as Activated Carbon Precursor

Thermal pyrolysis of mixed date stones and pistachio shells in a semi-batch reactor was addressed in this study. The highest yield of liquids (51.20 %) was produced at 500 °C, 90 min, 20 °C/min heating rate, and 50 mesh particle size. Under these conditions, yield of liquid from date stones and pistachio shells separately was 49.12 % and 47.67 %, respectively. The FT-IR results confirmed the presence of multiple oxygen-containing compounds in the bio-oil. Results from GC-MS declared that it was predominately composed of acids (57.57 %), esters (21.35 %), phenols (4.63 5), and alcohols (3.49 5). The obtained biochar was transformed into activated carbon (AC) by the optimized ZnCl2 activation method. The ideal AC was synthesized at 600 °C for 60 min using a 2 : 1 ZnCl2 : biochar impregnation ratio. FESEM and XRD measurements showed that the AC was amorphous. The prepared AC was effective in eliminating dibenzothiophene (DBT) from model fuel (200 ppm DBT/hexane) with a maximum performance 95.26 % at 40 °C for 1h using 0.35 g of the AC. The exhausted AC was regenerated and reutilized 4 times, and removal efficiency reached 88.23 % in the 4th cycle under ideal working conditions.

Semiconducting nanomaterials for photocatalytic desulfurization of liquid fuel under sunlight irradiation

Nanomaterials have fascinated the interest of researchers due to their unique electronic, optical, magnetic, and several other properties. Tin sulfide (SnS2) and Zinc oxide (ZnO) have emerged as promising materials for pharmaceutical, textile, environmental remediation, energy conversion, and storage device design. These two compounds were widely used in waste-water treatment for photocatalytic destruction of organic contaminants. However, the degradation of organic sulfur compounds in the liquid fuel desulfurization process has rarely been investigated using such materials. We hereby, present a hydrothermal method for developing the hexagonal lattice structure of SnS2 and ZnO for the deep desulfurization of model liquid fuel. These materials were further characterized through powder X-ray diffraction for phase purity and crystalline, FTIR analysis to validate functional groups, N2 adsorption-desorption isotherm to study surface properties, UV–vis diffuse reflectance spectroscopy for band gap analysis, scanning and transmission electron microscopy for morphology analysis. The optical behavior reveals that the energy gap for SnS2 and ZnO is 2.09 and 3.21 eV, respectively which corresponds to the visible light absorption range. The photocatalysis experiment was carried out in direct sunlight to degrade 10 ppm DBT in iso-octane. The obtained results show that 60% of the DBT degrade with SnS2 and 15% of the DBT degraded with ZnO in 120 min, with a first-order kinetics rate constant of 0.009 and 0.001 min−1 respectively.