Purification of 2-Pyrrolidone by Falling Film Melt Crystallization

Abstract

Industrial grade 2-pyrrolidone with a purity of 99.5% is produced by aminolysis of γ-butyrolactone and subsequent fractional distillation, but it still contains trace amounts of γ-butyrolactone and other impurities. Falling film melt crystallization was applied for further purification of 2-pyrrolidone from 99.5% to a very high purity. The effects of the precooling temperature, feed rate, cooling rate, final crystallization temperature, heating rate, and final sweating temperature on the purity and yield of 2-pyrrolidone were studied. 2-Pyrrolidone was purified by falling film melt crystallization to a purity and yield of more than 99.9 and 73.3%, respectively. The mathematical model of falling film crystallization was applied for simulation of the crystal layer growth of 2-pyrrolidone. The simulated average thickness of the crystal layer was in good agreement with the experimental values, demonstrating the applicability of the model to falling film crystallization of 2-pyrrolidone.

Purity-Targeted Prediction of the Cooling Profile in Layer Melt Crystallization via Thermal Approximation

“…Melt crystallization is widely used in the chemical separation process because of its low energy consumption and solvent-free process . Layer melt crystallization is a simple and practical technique that has been used in separation processes for many high-purity chemicals. − Modeling studies can help to explore the crystal layer growth mechanism and design the crystallization process. − …”

Purification of p-Cresol, o-Cresol, m-Cresol, and 2,6-Xylenol from the Quaternary Mixture by Three-Phase Crystallization

“…Three-phase crystallization (TPC), also known as stripping crystallization, was initially introduced by Shiau and his co-workers to separate mixed xylenes with close boiling temperatures. − Later, they applied TPC to separate chiral mixtures with the same boiling temperatures. − Basically, TPC combines melt crystallization and vaporization. Melt crystallization has long been adopted to obtain the desired crystalline solid from a liquid mixture via the solid–liquid transformation due to cooling at normal pressure. − TPC resembles melt crystallization operated at reduced pressure during the cooling process, leading to the formation of a crystalline product along with a vapor mixture from the liquid mixture via a series of three-phase transformations. If nearly all the liquid mixture is removed at the end of TPC, the final product only consists of the desired crystalline solid while the produced vapor can be collected and recycled.…”

Chiral Purification of S‐Methyl‐2‐chloropropionate from Enantiomer Mixtures by Three‐Phase Crystallization

“…Basically, TPC is a new separation technology, which combines melt crystallization and vaporization. For melt crystallization, the desired crystalline solid is formed from a liquid mixture via the solid-liquid transformation occurred at normal pressure during the cooling process [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. TPC resembles melt crystallization operated at reduced pressure during the cooling process, leading to the formation of desired crystalline solid along with vapor mixture from a liquid mixture via a series of three-phase transformations [1][2][3][4][5][6][7][8].…”