The heterogeneous heteropolyacid-catalyzed acetalization of glycerol with acetone was investigated under solvent-free conditions. In this work, the calcined Ta/W mixed addenda heteropolyacid catalyst ({H 20 }-355) was employed as a solid acid catalyst and showed much higher activity than these soluble Keggin-type catalysts in the acetalization of glycerol with acetone due to its superacidity ( H 0 = −12.95). Meanwhile, it showed high stability in catalytic recycles and extended for acetalization of glycerol with the other aldehydes and ketones . Based on the catalyst characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), 31 P NMR spectra, FT-IR spectra, pyridine-absorbed FT-IR, and Hammett acidity functions ( H 0 ) by UV–vis spectroscopy, it was found that the acidic strength of the Ta/W mixed addenda heteropolyacid was highly dependent on the contents of crystalline water that could be tuned by calcination temperature. Notably, the solid superacid catalyst {H 20 }-355 was swollen by acetone, exhibiting an interesting “pseudo-liquid” behavior, which served as a microreactor and facilitated the reaction. Furthermore, after the acetalization reaction of glycerol with furfural (98% yield of acetal) on {H 20 }-355 catalyst, the furan ring of the acetal products can be hydrogenated sequentially into dioxolane or dioxane with Pd/C catalyst under room temperature condition without the need of any isolation procedure.
Rational design of catalytic packing is crucial in developing reactive distillation (RD) processes as efficient in-situ coupling of reaction and separation is required. Structured catalytic packings are advantageous than the conventional packings (e.g., inert packing + catalyst ‘tea bags’), due to the integration of the catalysis and separation function in one unit, mitigating mass/heat transfer limits. Herein, we present one of the latest developments in the field of structured catalytic packings, which was applied to a pilot-scale RD process of ethyl lactate (EL) synthesis via acid-catalyzed esterification and showed the advantages. The tungstophosphoric acid and hierarchical Y zeolite were uniformly decorated on corrugated silicon carbide (SiC) foam sheets via new preparation method (of ultrasound-assisted impregnation and microwave-assisted drying). The activity of the resulting materials was first assessed in a batch reactor, then the best candidate was employed by the pilot process. Findings from the pilot-scale RD experiments show that the developed structured SiC foam catalytic packing (SSFCP) exhibited an excellent performance (with the normalized conversion of 0.155 mol/g catalyst ), outperforming the conventional seepage catalytic packing internal (0.002 mol/g catalyst ). The influence of various variables (including molar feed ratio, feed position and reflux ratio) on the process performance of the pilot RD rig was also investigated and optimized, achieving a lactic acid conversion of 46.9 % and EL purity of 44.9 % (bottom). The good performance was attributed to the improved mass transfer thanks to SiC foam corrugated sheet (which encourage the vortex formation), thereby enabling more efficient coupling with the reaction. The SSFCP demonstrated reasonable stability, making it a promising candidate for relevant practical RD applications.
危险品化学品经营许可证（带存储）