Preparation of biodiesel from tung oil catalyzed by five Brǒnsted acidic ionic liquids (ILs) with propyl sulfonic acid group was investigated. These ILs show good catalytic activity for the transeserification of tung oil. Among these ILs, [C3SO3Hmim]HSO4 showed a highest catalytic activity. In addition, these ionic liquids had a good reusability and could be easily separated from the biodiesel.

A new ionic liquid, N-octyl-2-pyrrolidonium chloride (NOPC), were synthesized and evaluated as inhibitors for mild steel (Q235) corrosion in 1 mol/L HCl. The adsorption behavior and corrosion inhibition mechanism of NOPC for mild steel in HCl solution were investigated by using weight loss measurements, electrochemical techniques, and SEM. The inhibition efficiency increases with the increasing concentration of NOPC in 1 mol/L HCl and decreases as the temperature increases. The results indicate that NOPC is able to function as a mixed type inhibitor.

Transesterification were carried out under microwave irradiation conditions and the effects of imidazolium hydroxide with different branched alkyl side-chains ([Cnmim]OH, n = 2, 3, 4) were investigated. The results showed that less than conventional amount of NaOH, and the alkaline ionic liquids formed clearly biphasic systems immediately after the transesterification of soybean oil with methanol was finished. The method offers significant improvement over conventional techniques in terms of operational simplicity, processing time reduction and excellent yields. Among the imidazolium salts studied, [C2mim]OH proved to be the most efficient catalyst, affording 96 % yield.

An ionic liquid, 2-Pyrrolidonium hydrogen sulfate (IL, [Hnhp]HSO4) together with a rectification column, was applied in continuous preparation of n-butyl acetate (n-BuAc) from n-butanol (n-BuOH) and acetic acid (HAc). [Hnhp]HSO4 was used as a catalyst which showed good activity for the esterification. Optimum conditions were as follows: base fluid n(HAc):n(n-BuOH): n(IL) =6:1:0.3 in reactor at 120 °C, feedstock n(n-BuOH):n(HAc) =1.05:1 by feeding to the reactorat 20 mL·h-1, aqueous reflux 18 mL·h-1 by feeding to the upper segment of the column and reflux ratio 1. During 48 hours of continuous reaction time, n-BuAc content ranged from 97 % to 85 % in the ester phase from overhead liquid-liquid separator and the reactive distillation system could maintain a good balance.

A series of Brönsted acidic ionic liquids based on 2-pyrrolidonium, 1-methylimidazolium, morpholinium and 4-methylmorpholinium cations ([Hnhp]+, [Hmim]+, [Hnhm]+ and [Hnmm]+) with anions HSO4ˉ and BF4ˉ, were synthesized. Their catalytic activities in the esterification of n-butyric acid with ethanol were studied and the relationships between catalysis performance and acidity were discussed. The optimum conditions of the esterification were determined as follows: 80 °C oil bath, n (n-butyric acid): n (ethanol): n ([Hnhp]HSO4) = 1:1.2:0.4 and t = 2 h, the yield of ethyl butyrate could reach 86%. There is no appreciable decrease of catalyst activity of [Hnhp]HSO4 after 5 cyclic repetitions.