Benzoylation of substituted arenes using Zn-and Fe-exchanged zeolites as catalysts

Fly Ash-Based Geopolymers as Sustainable Bifunctional Heterogeneous Catalysts and Their Reactivity in Friedel-Crafts Acylation Reactions

This study presents the synthesis, characteristics and catalytic reactivity of sustainable bifunctional heterogeneous catalysts derived from coal fly ash-based geopolymer, particularly those with a high Ca content (C-class) fly ash. The developed catalysts were synthesized at room temperature and pressure in a simple ecologically-benign procedure and their reactivity was evaluated in the Friedel-Crafts acylation of various arenes. These catalysts can be produced with multilevel porous architecture, and a combination of acidic and redox active sites allowing their use as bifunctional catalysts. The acidic sites (Lewis and Brønsted acidic sites) were generated within the catalyst framework by ion-exchange followed by thermal treatment, and redox sites that originated from the catalytically reactive fly ash components. The developed catalysts demonstrated higher reactivity than other commonly used solid catalysts such as Metal-zeolite and Metal-mesoporous silicate, heteropolyacids and zeolite imidazole frameworks (ZIF).

An efficient Fe2O3/HY catalyst for Friedel–Crafts acylation of m-xylene with benzoyl chloride

Iron oxide supported on HY zeolite was prepared and exhibited excellent catalytic performance in the acylation of m-xylene with benzoyl chloride. It was characterized by XRD, BET, XPS, NH₃-TPD and Py-IR. The catalytic activity of Fe₂O₃/HY is enhanced with the increase of Lewis acidic sites. Furthermore, the reaction parameters were optimized. Finally, the catalyst was easily separated reused for five runs without appreciable loss of catalytic activity.

Catalytic wet peroxide oxidation of azo dye (Congo red) using modified Y zeolite as catalyst

The present study explores the degradation of azo dye (Congo red) by catalytic wet peroxide oxidation using Fe exchanged commercial Y zeolite as a catalyst. The effects of various operating parameters like temperature, initial pH, hydrogen peroxide concentration and catalyst loading on the removal of dye, color and COD from an aqueous solution were studied at atmospheric pressure. The percent removals of dye, color and COD at optimum pH(0) 7, 90 degrees C using 0.6 ml H(2)O(2)/350 ml solution and 1g/l catalyst was 97% (in 4h), 100% (in 45 min) and 58% (in 4h), respectively. The % dye removal has been found to be less in comparison to % color removal at all conditions, e.g. dye removal in 45 min and at above conditions was 82%, whereas the color removal was 100%. The results indicate that the Fe exchanged Y zeolite is a promising catalyst for dye removal. Fe exchanged catalyst is characterized using XRD, SEM/EDAX, surface area analyzer and FTIR. Though the dye, color and COD removals were maximum at pH(0) 2 but as the leaching of Fe from the catalyst was more in acidic pH range, pH(0) 7 was taken as operating pH due to almost comparable removals as of pH(0) 2 and no leaching of Fe ions.