Synthesis Of 2-ethylanthraquinone Catalyzed By Modified β Molecular Sieve

As an extremely significant chemical and intermediate in fine chemical industry,2-ethylanthraquinone is widely used in the production process of dyestuff,coating,resin,organic photocatalyst,food,medicine,pesticide and other areas.Nowadays,the most common method for synthesizing 2-ethylanthraquinone is phthalic anhydride method,but this method uses a large amount of AlCl₃ and concentrated H₂SO₄ as catalysts,which produces a lot of waste acid and other wastes,making the pressure of"three wastes"management extremely.In recent years,zeolite molecular sieve,as a new type of green solid acid catalyst,has been applied in various chemical reactions with excellent catalytic effect because of its adjustable texture and acidity,easy separation from the reaction system and environmental friendliness.Therefore,this study from several different structure and acid molecular sieve to determine the synthesis of 2-ethylanthraquinone reaction catalytic effect of the best carrier,modified to replace the traditional liquid catalyst,in order to achieve the one-step synthesis of 2-ethylanthraquinone by PHA high-performance green catalysis.Firstly,several H-type zeolites with different structures（HUSY,HZSM-5,HMOR and Hβ）were used as catalysts to catalyze the one-step synthesis of 2-ethylanthraquinone reaction by phthalic anhydride method,and the results showed that Hβzeolite have the best catalytic performance due to its suitable texture and acidity.Then the optimum conditions for the catalytic synthesis of 2-ethylanthraquinone by Hβmolecular sieve were determined:the reactants with material ratio of n（ethylbenzene）:n（phthalic anhydride）=8:1（2.45 m L ethylbenzene and 0.37 g PHA）and 0.5 g of Hβzeolites with silica-alumina ratio of 30 were reacted at 250℃ for 5 h.The conversion of PHA and the selectivity of 2-EAQ were 37.1%and 42.8%,respectively.The optimum regeneration of the zeolites was determined by SEM and experiments.After the reacted zeolites was washed with organic solvent and dried thoroughly,the Hβzeolites obtained by calcination in a chamber resistance furnace at 550℃ for 5 h showed no significant decrease in catalytic activity after four times of reuse,and the conversion of PHA and the selectivity of 2-EAQ only decreased to 30.4%and 34.7%.In order to further improve the catalytic activity of the catalyst,four rare earth metals,including light rare earth La,Ce,medium rare earth Sm and heavy rare earth Y,were choose to modify the Hβmolecular sieve as a carrier and used in the reaction study of catalytic synthesis of 2-ethylanthraquinone by phthalic anhydride method.The data displayed that the catalytic effect of Hβzeolite modified with Y element was the best,and the conversion of PHA was enhanced to 43.6%and the selectivity of 2-EAQ was enhanced to 65.3%under the same reaction conditions as in the previous chapter.By varying the loading of Y species on the Hβzeolites and optimizing the reaction conditions,the influences of different Y loading on the structure,weave and acid properties of Hβzeolites were investigated by XRD,TEM,SEM,N₂ physical adsorption-desorption,NH₃-TPD,Pyridine-IR and other characterization means.The results showed that the material ratio of n（ethylbenzene）:n（phthalic anhydride）=10:1and 0.75 g of 10Y-Hβcatalyst reacted with stirring at 250℃ for 5 h.The conversion of PHA and the selectivity of 2-EAQ were enhanced to 81.6%and 82.7%,respectively;the Y species in a highly dispersed state on the Hβmolecular sieve did not change the BEA characteristic structure of the zeolite itself,but instead interacted with the Hβmolecular sieve,and enhanced the amount and acid strength of the zeolites,especially the amount of medium and strong acid,strong acid and L acid,and the synergistic catalytic effect produced by L acid and B acid greatly promoted the synthesis of 2-ethyl anthraquinone reaction.Finally,when the recycling performance of Y-Hβmolecular sieve was investigated,it was found that the catalytic activity decreased after five times of repeated use,and the conversion of PHA and the selectivity of 2-EAQ decreased to 72.5%and70.4%,respectively.The characterization results of ICP,TG and SEM showed that the loss of Y species and coking carbon accumulation on Y-Hβmolecular sieve were the main reasons for the decrease of catalytic performance,in addition,the repeated use of zeolites particles appear agglomeration or even fragmentation phenomenon.In order to further improve recyclability of Hβzeolites,three non-metallic silicon（Si）,boron（B）,phosphorus（P）and rare earth metal Y composite modified Hβzeolites were prepared using a co-impregnation method and used in the catalytic synthesis of 2-ethylanthraquinone,the results showed that the B species modified Y-Hβzeolites exhibited the best catalytic performance,which was attributed to the fact that the B species modified Y-Hβzeolites with weak acid,strong acid amount and B acid to be greatly improved.By varying the content of B and Y species on the zeolites and performing single-factor experiments,it was found that the material ratio of n（ethylbenzene）:n（phthalic anhydride）=10:1（3.05 m L ethylbenzene and 0.37 g PHA）and 0.75 g of 1B-10Y-Hβcatalyst reacted at 250℃ for 5 h.The conversion of PHA was79.2%and the selectivity of 2-EAQ was enhanced to 88.4%.Additional characterization results showed that the interaction between B and Y species favorably affected the zeolite structure and acidity:1B-10Y-Hβzeolites had the largest specific surface area and pore volume and more balanced acid strength and acid amount.When the recyclability of the 1B-10Y-Hβzeolites was examined,it was found that the catalyst showed only a slight decrease in PHA conversion and 2-EAQ selectivity after five uses,72.5%and 83.1%,respectively,which were superior to the 10Y-Hβmolecular sieve.The characterization results indicated that the leaching of B and Y species on the catalyst was greatly reduced due to the interaction between B and Y species on the Hβzeolites.In summary,the carrier molecular sieve with the best catalytic activity for the synthesis of 2-ethylanthraquinone reaction and the best regeneration method of deactivated catalyst were first screened,then the pore structure and acid properties of the catalyst were adjusted by modifying the carrier molecular sieve with single metal and double active sites.It can catalyze the synthesis of 2-ethylanthraquinone with high performance and good recycling performance,and provides an important reference for the research of new green catalysts for the reaction of 2-ethylanthraquinone.