Snthesis Of Anthraquinone Catalyzed By Zeolite Molecule Sieves

Anthraquinone(AQ)is an important raw material and intermediate,widely used in the synthesis of liquid crystal materials,dyes,pesticides,and pharmaceuticals.At present,the industry adopts the"two-step"acylation reaction of phthalic anhydride and benzene to prepare AQ,which has the problems of a large amount of catalyst sulfuric acid and aluminum trichloride,equipment corrosion and serious environmental pollution,and difficulty in recycling the catalyst.As a green catalytic material,molecular sieves have been successfully used in alkylation,acylation,esterification and Mannich reactions.They have high thermal stability,high acid site density,adjustable acidity,and unique pore structure.It also has unique advantages in catalyst modification and screening.Therefore,this study intends to prepare a catalyst with a good catalytic performance for the synthesis of AQ by modifying H?molecular sieve.The conventional ammonium exchange method was used to modify the four catalytic materials such as?,Y,ZSM-5 and MOR and used to catalyze the synthesis of anthraquinone.The results showed that:compared with the traditional heating method,microwave-assisted heating significantly shortened the catalyst modification Time(10min)to improve the catalytic performance(compared to the catalytic performance of the catalyst obtained after three exchanges using the traditional heating method).The results showed that the H?modified by microwave at 600 w,80 ~oC has the best catalytic performance.Under the optimal reaction conditions of 1.3 g catalyst,the molar ratio of benzene to phthalic anhydride 4,reaction temperature 250?,reaction time 5 h,stirring rate 500 r/min,the conversion rate of phthalic anhydride and the selectivity of AQ were14.77%and the selectivity of 60.43%,respectively.After the catalyst was regenerated and reused 5 times,its activity was not significantly reduced.Besides,XRD characterization results show that microwave-assisted heating does not destroy the molecular sieve framework.Using microwave-assisted heating,five small molecular organic acids such as malic acid,tartaric acid,malonic acid,oxalic acid,and acetic acid were used to acid-modify the H?molecular sieve and used to catalyze the synthesis of AQ.The results showed that the catalytic performance of H?modified by acetic acid under the microwave 600 w 80 ~oC is the best.Under the optimal reaction conditions of catalyst HAc(0.9)-H?dosage 1.3 g,the molar ratio of benzene to phthalic anhydride 4,reaction temperature 250?,reaction time 5 h,stirring rate 500 r/min,the conversion rate of dicarboxylic anhydride is 54.72%,and the selectivity of AQ is 62.56%;the high catalytic energy of modified H?molecular sieve is due to the suitable acid strength,large specific surface area and pore volume,and the modification of small molecule organic acid While maintaining the topological structure of the H?molecular sieve,the sexual treatment increases the crystallinity of the H?molecular sieve,adjusts its acid strength,changes the specific surface area and pore volume;the repeated use performance of the catalyst shows that the production of carbon deposits causes the catalyst to lose The main reason for liveness,and calcination regeneration can effectively remove carbon deposits and restore the catalytic activity of the catalyst.Using microwave-assisted heating,five metal salts such as nickel nitrate,zirconium nitrate,copper nitrate,iron nitrate,and zinc nitrate were used to modify the H?molecular sieve and used for catalytic synthesis of AQ.The results showed that the catalytic performance of H?modified by nickel nitrate in microwave 600 w,80 ~oC is the best.Under the optimal reaction conditions of catalyst Ni(1.3)-H?dosage 1.1 g,the molar ratio of benzene to phthalic anhydride 4,reaction temperature 250?,reaction time 4 h,stirring rate 500 r/min,the conversion rate of phthalic anhydride is 63.57%,and the selectivity of AQ is 68.48%;the catalytic activity of the modified H?is affected by many factors.The introduction of strong acid sites and the increase of acid density both contribute to the conversion of the reaction The high selectivity depends on the appropriate acid strength;the catalyst's reuse performance research shows that the generation of carbon deposits is the main cause of catalyst deactivation,and calcination regeneration can effectively remove carbon deposits and restore the catalytic activity of the catalyst.This paper studies the application of zeolite in the synthesis of anthraquinone.Through various modification methods,the performance of the zeolite is adjusted to make it have good catalytic activity and high reusability.Replacing the traditional acid catalyst with zeolite not only has a simple process but also realizes the green reaction,which provides an important theoretical basis for the future exploration of the green process of anthraquinone.