Polyethyleneimine (PEI), a potent architecture backbone was explored for the synthesis of novel polymeric ionic liquids (PolyE-ILs) with protagonist properties. The simple quaternization of PEI dendrimer with Bronsted acids (H 2 SO 4 , H 3 PO 4 , CH 3 SO 3 H, CF 3 COOH and TsOH) leads to formation of series of protic PolyE-ILs with corresponding counter anions [HSO 4 ] À , [H 2 PO 4 ] À , [CH 3 SO 3 ] À , [CF 3 COO] À and [TsO] À. The physicochemical properties of synthesized PolyE-ILs were studied by using TGA, Hammett acidity, hydrodynamic radii, solubility, and elemental analysis. PolyE-ILs showed characteristic Hammett acidity (0.94-1.78), good thermal stability (< 250°C) and enhanced hydrodynamic radii. However, use of PolyE-IL can be promoted for their wide applications as an acid catalysts. The reported PolyE-IL-1 with sulfonic acid counter ion was explored as catalyst for esterification of (E)-cinnamic acids and it showed good catalytic activity. The enhanced hydrodynamic radii due to the branched architecture of PEI dendrimers facilities the separation process via Nanofiltration (NF) membrane with no membrane fouling. Thus, PolyE-ILs can be highly active, easily recoverable, and reusable catalyst for esterification reactions with superior sustainability and economics. In addition to this the present one pot PolyE-IL synthesis process is non-complex and simple as compared to conventional post polymerization, ion exchange, and nucleophilic addition etc., strategies for synthesis of PILs.

No abstract

The lignocellulosic biomass has been identified as a potential renewable feedstock for production of levulinic acid (LA). In the present study, the catalytic thermo liquefaction (CTL) process for liquefaction of rice straw into LA was studied by integrating the polyethyleneimine functionalized acidic ionic liquid (PolyE-IL) catalyst. The screening of various PolyE-IL catalysts with variable counter ions showed the remarkable formation of carbohydrates, LA, formic acid, and acetic acid (AA). Among the tested PolyE-IL catalysts, PolyE-IL with a [HSO4]− counter ion showed the maximum conversion efficiency. The process intensification study to evaluate the influence of reaction parameters such as catalyst concentration, reaction temperature, time, and slurry concentrations was conducted to achieve the maximum conversion and yield of organic acids. Moreover, the influence of feedstock pretreatment was also studied. The pretreated rice straw provided maximum yields of LA and FA. The intensified CTL process for untreated rice straw resulted in 49.8% LA, 50.5% FA, and 100% AA, while CTL of pretreated rice straw resulted in 65.5% LA, 75.8% FA, and 26.7% AA of the theoretical maximum at 210 °C for 120 min. The separation of the catalyst and other liquefaction products was achieved using adsorption followed by membrane separation processes. The adsorption process leads to separation of the undesired polymeric side products, while membrane separation provides efficient separation of the catalyst and organic acids with >98% efficiency. The undesired side products separated in the adsorption process were concentrated as CTL-Oil and characterized for physiochemical properties. CTL-Oil is C-, H-, and O-rich feedstock with a caloric value of 24–26 MJ/Kg and thus could be explored for multiple fuel and energy applications. Thus, an efficient valorization of rice straw was achieved using a recyclable, robust, and efficient catalyst.

No abstract

No abstract