Zhang Suojiang

Simultaneous desulfurization and denitrogen of liquid fuels using two functionalized group ionic liquids

Deep desulfurization of liquid fuels is an important and challenging issue in worldwide petroleum refining industry. Extraction and catalytic oxidative desulfurization (ECODS) of liquid fuels using a series of ionic liquids (ILs) with two functionalized groups, such as [(CH2)2COOHmim]Cl/nFeCl3, [(CH2)2COOHmim]Cl/nZnCl2, and [Amim]Cl/nFeCl3, was studied. In the ECODS, the ILs were used as both extractant and catalyst and 30 wt% hydrogen peroxide (H2O2) solution as oxidant. The effects of molar ratios of [(CH2)2COOHmim]Cl (or [Amim]Cl) to FeCl3 (or ZnCl2) in ILs, H2O2/sulfur (O/S) molar ratio, reaction temperature, and the nature of sulfur compounds on sulfur removal were investigated. The natures of the functional groups (-COOH, -CH2-CH=CH2) in cations and the acid strength of anions play important roles in the ECODS and affect the reaction time, temperature, and desulfurization efficiency of different substrates. Also, nitrogen-containing compounds (pyridine, pyrrole, and quinoline) could be removed simultaneously in the ECODS and had different effects on dibenzothiophene removal.

Study on the recovery of ionic liquids from dilute effluent by electrodialysis method and the fouling of cation-exchange membrane

With the wide application of ionic liquids (ILs) in various fields, developing efficient techniques to recover ILs from effluent is an urgent demand for the cost reduction and the environmental protection. In this study, an electrodialysis (ED) method was used to recover 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) IL from aqueous solution as model effluent. The influences of initial IL concentration and applied voltage on the current efficiency, removal ratio, desalination ratio, membrane flux and specific energy consumption during the ED process were investigated. It was found that the removal ratio and desalination ratio increases with the increasing of initial IL concentration and applied voltage. The current efficiency decreases with the increasing of initial IL concentration and the current efficiency reached the maximum value of 94.3% at 25 V. Besides, as the applied voltage increases, the membrane flux increases and the specific energy consumption decreases. Moreover, the fouling of cation-exchange membrane was also discovered after the desalination of IL. The deposits on the surface or into the membrane which is probably caused by [Bmim]+ was characterized by scanning electron microscopy, elemental analysis and Fourier transform infrared.

Computational studies of the structure and cation-anion interactions in 1-ethyl-3-methylimidazolium lactate ionic liquid

Quantum chemical calculations of the structures and cation-anion interaction of 1-ethyl-3-methylimidazolium lactate ([Emim][ LAC]) ion pair at the B3LYP/6-31++G** theoretical level were performed. The relevant geometrical characteristics, energy properties, intermolecular H-bonds (H-bonds), and calculated IR vibrations with respect to isolated ions were systematically discussed. The natural bond orbital (NBO) and atoms in molecule (AIM) analyses were also employed to understand the nature of the interactions between cation and anion. The five most stable geometries were verified by analyzing the relative energies and interaction energies. It was found that the most of the C-H…O intermolecular H-bonds interactions in five stable conformers have some covalent character in nature. The elongation and red shift in IR spectrum of C-H bonds which involve in H-bonds is proved by electron transfers from the lone pairs of the carbonyl O atom of [LAC]− to the C-H antibonding orbital of the [Emim]+. The interaction modes are more favorable when the carbonyl O atoms of [LAC]− interact with the C2-H of the imidazolium ring and the C-H of the ethyl group through the formation of triple H-bonds.

All-atom and united-atom simulations of guanidinium-based ionic liquids

Ionic liquids (ILs) have been widely used in separation, catalysis, electrochemistry, etc., and one of the most outstanding characteristics is that ILs can be tailored and tuned for specific tasks. In order to design and make better use of ionic liquids, the structures and properties relationship is indispensable. Both molecular dynamics and Monte Carlo simulations have been proved useful to understand the behavior of molecules at the microscale and the properties of the system. However, the quality of such simulations depends on force field parameters describing the interactions between atoms. All-atom (AA) or the united-atom (UA) force fields will be chosen because of the demand for more exact results or the lower computational cost, respectively. In order to make a systematic comparison of the two force fields, molecular simulations for four kinds of acyclic guanidinium-based ionic liquids (cations: (R2N)2C=N+<, anion: nitric or perchloric acid) were performed based on the AA and the UA force fields in this work. AA force field parameters were derived from our previous work (Fluid Phase Equilib., 2008, 272: 1–7), and the UA parameters were proposed in this work. Molecular dynamics simulation results for the AA and UA force fields were compared. Simulation densities are very similar to each other. Center of mass radial distribution functions (RDFs), site to site RDFs and spatial distribution functions (SDFs) were also investigated to depict the microscopic structures of the ILs.

Extraction of coal-tar pitch using NMP/ILs mixed solvents

Coal-tar pitch (CP) is a promising carbon raw material for producing needle coke, carbon fiber etc. During processing, the H/C ratio, ash content, and quinoline insoluble (QI) in the CP are the key factors that influence the material preparation. In this study, NMP was selected to extract CP first; then [BMIM]Cl/NMP mixed solvent was used; and finally a series of ionic liquids (ILs) mixtures with NMP were developed for the extraction of CP to obtain the refined pitch. The extracts were analyzed via elemental analysis, TGA, FT-IR, and 13C-NMR. Results indicate that different NMP/IL mass ratios or different kinds of ILs have impact on the extraction yield. The relationship of the hydrogen to carbon (H/C) ratio changed with different solvents and QI extracts were obtained. Results showed that the H/C ratios changed little between NMP extracts and could be adjusted by changing the NMP/ILs mass ratio or using different ILs. The extracts are suitable for preparation mesophase pitch because of no ash content, low QI, and appropriate H/C ratios. As a result, NMP can be used to refine pitch. In addition, [BMIM]Cl is good mixed with NMP for CP extraction, because it can obtain a relatively high yield under the same extraction conditions.

The density and viscosity of aqueous solutions of quaternary ammonium-amino acid ionic liquids

Three quaternary ammonium-amino acid ionic liquids ([N2222][AA]) tetraethylammonium L-a-aminopro- pionic acid salt ([N2222][Ala]), tetraethylammonium L-amino-3-hydroxypropionic acid salt ([N2222][Ser]), and tetraethylammonium L-aminosuccinic acid salt ([N2222][Asp]) were prepared by the neutralization method and characterized by 1H NMR, 13C NMR, IR and elemental analysis. The density and viscosity of binary mixtures ([N2222][AA] + water) with different compositions were determined at T = 293.15-343.15 K by using an Anton Paar DMA 5000 densimeter and an Anton Paar AMVn measuring assembly systematically. The temperature dependence of density and viscosity for [N2222][AA] and water mixtures can be described by an empirical linear equation and by the Vogel-Tammann-Fucher (VTF) equation, respectively. The excess volume ( V E) and viscosity deviation (Δ η ) were calculated and correlated by Redlich-Kister polynomial equation, respectively. Based on the measured and derived properties, the influence of the interaction between ILs and water and hydrogen bonds formed between amino acid ionic liquids (AAILs) and water on density and viscosity were analyzed.

Ionic liquids catalyzed green processes

Fundamental research on ionic liquids has promoted their wide applications including catalysis, organic synthesis and materials, which provides new method for developing green catalysis processes. This article reviews some representative ionic liquid-based catalytic reactions, such as CO2 cycloaddition, alkylation, hydroformylation, transesterification, oxidation, CO2 hydrogenation, cross-polymerization and depolymerization, with the aiming of highlighting the roles of ionic liquids on reaction efficiency, the reduction of emissions and separation. Furthermore, the prospective to the development in this field is discussed.