Electrooxidative Desulfurization of a Thiophene-Containing Model Fuel Using a Square Wave Potentiometry Technique

Abstract

A dynamic electrochemical technique was used for desulfurization of thiophene-containing solutions. First, adsorption of thiophene from an aqueous solution onto a platinum electrode surface and electrooxidative behavior of thiophene were studied using a cyclic voltammetry technique, and then, a square wave potentiometry method was utilized to electrochemically desulfurize the aqueous thiophene solution and a thiophene-containing model fuel. Results indicated that, for thiophene molecules, the best adsorption potential is 0.2 V and the maximum electrooxidation rate occurs at 1.1 V. Also, the optimal square wave frequency was found as 50 Hz. Ion chromatographic measurement of sulfate ion concentration revealed that reaction conversion was 100% in the electrooxidative desulfurization of aqueous thiophene solution. The high desulfurization efficiency can be attributed to excellent electrocatalytic activity of the platinum electrode and performing experiments at the best operating conditions. On the basis of gas chromatographically quantitated thiophene concentration in the hydrocarbon phase, desulfurization reactions reached a conversion of about 88% during electrooxidative desulfurization of a model fuel/aqueous electrolyte emulsion. The lower desulfurization efficiency can be attributed to addition of a mass transfer (from hydrocarbon to aqueous phase) resistance and lessening the overall thiophene concentration. Ion chromatographic analysis of the aqueous phase revealed that only 38% of thiophene molecules were completely oxidized to sulfate ions. Fourier transform infrared spectroscopy studies of the hydrocarbon and the aqueous phases showed that the remaining part of converted thiophene molecules were partially oxidized to a sulfone and an organic sulfate compound. Due to polarity of these components, which results in their aqueous phase solubility, no more steps were required to separate the products of desulfurization from the hydrocarbon phase. On the basis of the obtained results, electrochemical desulfurization can be proposed as an effective alternative for the commercial hydrodesulfurization processes.

“Sweet” ionic liquid gels: materials for sweetening of fuels

“…DSC measurements were carried out using a Q20 instrument calibrated using indium as standard and TA Instruments Modulated DSC Q 2000 V24. 4 Build 116 with a refrigerated cooling system RCS 90 capable of controlling the temperature down to 220 K. Samples were weighed and hermetically sealed in aluminum pans. Heating and cooling rates were 10 °C min -1 for the salts samples and 5…”

“…Please do not adjust margins collected, induces us to carry out investigation at 20 °C, also to limit the energy demand of the process. The next evaluation was the determination of the optimum time needed to obtain the highest AE value for [P 4…”

“…This is the reason why different methods like oxidative, biological, adsorptive and extractive desulfurisation have been taken into account. [4][5][6][7] Obviously, regardless of methodology, the materials used in this process should possess low toxicity, efficient reusability and low costs. As far as adsorption methods are concerned, different solid sorbents such as carbon beads, 8 graphene oxides, 9 functionalised polymers, 10, 11 metal oxides 12 etc.…”

Electrochemical oxidation of dibenzothiophene compounds on BDD electrode in acetonitrile–water medium

“…approach to liquid fuel desulfurization [15][16][17][18][19][20]. The ECDS method is advantageous compared to HDS since it is carried out at low reaction temperatures and pressures, in the absence of hydrogen.…”

Model Fuel Deep Desulfurization Using Modified 3D Graphenic Adsorbents: Isotherm, Kinetic, and Thermodynamic Study

“…As the fuels used in different types of fuel cells need to have ultralow amounts of sulfur pollutants, preparation of a clean fuel source for hydrogen production is required . Hydrodesulfurization (HDS) is the most common strategy for removing organic sulfur contents from diesel fuels. , HDS usually operates at a hydrogen pressure of 20–100 bar and a temperature range of 300–400 °C. , On the other hand, HDS is not efficient in removing aromatic sulfur compounds like benzothiophene (BT) and its derivatives. ,, Different alternatives such as oxidative desulfurization (ODS), electro-oxidation, use of membranes, biodesulfurization (BDS), extractive desulfurization (EDS), use of ionic liquids, and adsorptive desulfurization are used for desulfurization of fuels. ,,− Adsorptive desulfurization is an outstanding and promising approach for sulfur removal in order to reach ultralow concentrations because of its mild process conditions, selective removal possibility, various adsorbent availability, and relatively economically viable adsorption process. ,− Carbon materials are well- known adsorbents for various applications because of their appropriate porous structures and compatibility. , Activated carbon, mesoporous carbon materials (CMK), carbon nanotubes, carbon aerogels, graphenic materials, and their modified forms are mostly used for energy applications. − Nanostructured carbons are known as promising materials because of their green and sustainable nature, high surface area, high resistance under different conditions, and tunable surface properties. Graphene is a significant material because of its two-dimensional (2D) structure formed by a honeycomb lattice.…”