HPAs and POM‐based ILs Catalyzed Effective Conversion of Furfuryl Alcohol to Alkyl Levulinate

Abstract

Here we represented the heteropoly acids (HPAs) and polyoxometalate (POM)‐based ionic liquids (ILs) catalyzed the effective alcoholysis of furfural alcohol (FAL) to alkyl levulinate. H5AlW12O40 exhibited the highest catalytic activity among HPAs, furnishing > 99 % FAL conversion and 80 % yield of butyl levulinate (BL). The incorporation of IL framework containing sulfate group into HPAs resulted in the enhanced catalytic performance. [MIMBS]5[AlW12O40] achieved the highest BL yield of 94 % and maintained a good catalytic activity after 6 times of recycle and reuse experiments. The effect of the Hammett acidity and structure of catalyst on the catalytic performance of HPAs and POM‐based ILs was also investigated.

ZnCl2: A Green Brønsted Acid for Selectively Recovering Rare Earth Elements from Spent NdFeB Permanent Magnets

“…Various methods have been applied to measure the acidity of ZnCl 2 solution, such as Hammett acidity, , 13 C nuclear magnetic resonance (NMR), and infrared spectroscopy . Hammett acidity has been widely used to determine the acidity of inorganic acid, organic acid, aqueous solution, and non-aqueous solvent.…”

“…After thoroughly mixing, all of the solutions were placed in the dark at room temperature for 2 h, and then the absorbance of 4-nitroaniline was recorded by UV–vis spectroscopy. In the solution, indicator base type B and its conjugated acid (proton type BH + ) have a proton transfer reaction According to ion balance, Hammett acidity is defined as where K BH + is the ion equilibrium constant of the indicator and C BH + / C B is the proton-type concentration of the indicator to the base-type concentration of the indicator.…”

“…Ultraviolet−visible (UV−vis) spectroscopy was used to analyze the Hammett acidity of five ZnCl 2 solutions. The indicator 4-nitroaniline (pK BH + = 0.99, with a peak wavelength at 377.5 nm 36 ) was dissolved in ethanol (to prepare an all-alkali-type solution), 98% H 2 SO 4 (to prepare an all-proton-type solution), and five ZnCl 2 solutions, respectively, with a concentration of 8.5 mg/ L. After thoroughly mixing, all of the solutions were placed in the dark at room temperature for 2 h, and then the absorbance of 4-nitroaniline was recorded by UV−vis spectroscopy. In the solution, indicator base type B and its conjugated acid (proton type BH + ) have a proton transfer reaction.…”

“…In the solution, indicator base type B and its conjugated acid (proton type BH + ) have a proton transfer reaction. 36…”

Alcoholysis of Furfuryl Alcohol to Ethyl Levulinate Catalyzed by a Deep Eutectic Solvent

“…The application of supported heteropoly acid catalyst is limited due to its small specific surface area, poor adsorption capacity, and easy loss of active sites in the catalytic process . Alcoholysis can be catalyzed using a heteropoly ionic liquid (IL) containing a heteropoly acid and an IL using imidazole sulfonate and phosphotungstic acid as the cation and anion, respectively . This catalyst exhibits a good self-separation effect.…”