One-pot Synthesis Of 2-ethylanthraquinone Over A Modified Hβ Zeolite

2-Ethylanthraquinone occupies a very critical position in the synthesis of fine chemicals and in the storage and conduction of energy.In the traditional synthesis process,the large amount of Al Cl₃ and concentrated H₂SO₄ is used,which not only causes the process cost to increase,but also the waste acid and wastewater produced in the production process corrode the equipment and pollute the environment.Therefore,it is urgent to develop a green and effective heterogeneous catalyst under the double pressure of the rapid growth of 2-ethylanthraquinone demand and environmental protection demand.In recent years,Hβzeolite has been widely studied because of its three-dimensional cage-free twelve-element ring channels,pore size matching with 2-ethylanthraquinone and acidity adjustable.In this thesis,Hβzeolite was used as a support to further improve the activity and stability of the zeolite by modifying the pore structure and acid properties through metal modification.The specific studies are as follows.（1）In this thesis,five metals,Sc,Zr,Zn,Ce and Fe,were selected for the modification of Hβzeolite by isovolumetric impregnation method and used for the synthesis of 2-ethylanthraquinone by the one-pot method of phthalic anhydride and ethylbenzene.The results show that the catalyst modified with rare earth metal Sc has the best catalytic performance for Sc-Hβ.The optimum reaction conditions for the synthesis of 2-ethylanthraquinone were determined,namely:Sc loading of 5wt%,molar ratio of ethylbenzene to phthalic anhydride of 8:1（ethylbenzene 2.1 g,phthalic anhydride0.4 g）,catalyst dosage of 0.5 g,reaction temperature of 250°C,and reaction time of 5h.Under these conditions,the conversion of phthalic anhydride was 58.8%and the selectivity of 2-ethylanthraquinone was 78.5%.Sc is highly dispersed on Hβzeolite,and the introduced Sc can generate strong Lewis（L）acid center,increase the acid amount,adjust the Lewis/Br?nsted（L/B）acid ratio,and the two acidic active sites have a synergistic effect in the synthesis of 2-ethylanthraquinone to promote the reaction.Both strong L and weak L acids are favorable for the conversion of phthalic anhydride to 2-ethylanthraquinone,especially strong L acids,while only strong B and strong L acids are favorable for the dehydration of the intermediate 2-（4’-ethylbenzoyl）benzoic acid for the closed-loop synthesis of 2-ethylanthraquinone.In addition,the reusability of the catalyst was evaluated,and the catalyst was regenerated and reused four times,and the conversion of phthalic anhydride and the selectivity of 2-ethylanthraquinone were maintained at 40.7%and 60.7%,respectively.（2）To further improve the catalytic performance and reusability of the catalysts,bimetallic M（Y,Zr,Ni,Ce）-Sc-Hβcatalysts were prepared using yttrium nitrate,zirconium nitrate,nickel nitrate and ceric ammonium nitrate as the second metal precursors by equal volume impregnation.The characterization results showed that the catalysts prepared by co-impregnation were more uniformly dispersed with Sc and Ce,more acidic;the Sc and Ce species were highly dispersed on the Hβzeolite and their interactions increased the acid strength and adjusted the L/B acid ratio,so that the Hβzeolite had a suitable L acid and more B acid.The modified catalysts were used for catalytic synthesis of 2-ethylanthraquinone by the one-pot method of phthalic anhydride and ethylbenzene.The results showed that the catalytic performance of the catalytic synthesis of 2-ethylanthraquinone was best when the loading of both Ce and Sc was2.5wt%,and the molar ratio of ethylbenzene to phthalic anhydride was 8:1（ethylbenzene2.1 g,phthalic anhydride 0.4 g）,the catalyst dosage was 0.5 g,the reaction temperature was 250°C,and the reaction time was under the better reaction conditions of 5 h,the conversion of phthalic anhydride was 78.9%and the selectivity of 2-ethylanthraquinone was 71.1%,which was more favorable for the synthesis of 2-ethylanthraquinone.The enhanced acid strength of the synthesized catalyst,the introduced L-acid active center,supplemented with an appropriate B-acid active center facilitated the conversion of phthalic anhydride to 2-ethylanthraquinone with an optimum L/B of 2.06.In addition,the isolated and recovered catalyst maintained high activity after regeneration and reuse for six times.In this thesis,one pot synthesis 2-ethylanthraquinone from ethylbenzene and phthalic anhydride over metal-modified Hβzeolites was investigated.The higher conversion of phthalic anhydride and selectivity of 2-ethylanthraquinone were got by modified and regulated the structure and acidity of the zeolite,which provided a green and simple method for the synthesis of 2-ethylanthraquinone.