Liquid-phase cascade acylation/dehydration over various zeolite catalysts to synthesize 2-methylanthraquinone through an efficient one-pot strategy

Liquid-phase cascade acylation/dehydration reactions over various zeolite catalysts were performed to synthesize 2-methylanthraquinone (2-MAQ). Many characterization techniques such as NH3-TPD, pyridine-IR, BET, XRD, SEM, TEM, XRF, and TGA have been employed to study the relationship between the catalytic behavior and the nature of catalysts. The present work provides evidence that the acidity, pore size, particle size, and surface area of zeolites strongly affect both the catalytic properties and the coke formation. Moreover, it is discovered that the reaction activity of phthalic acid (PA) is higher than that of phthalic anhydride, and the yield of 2-MAQ reached 82.2% when PA was used, which opened a new avenue for one-pot synthesizing 2-MAQ by using PA as an acylation reagent. The catalyst can be recycled four times only with a slight decrease in activity. The nano-sized H-beta zeolite could be a promising liquid-phase cascade acylation/dehydration catalyst for clean one-pot synthesis of 2-MAQ.