Study On The Production Of 2,6-diisopropylnaphthalene By Shape-selective Alkylation Of Naphthalene And Isopropanol On Zeolite

2,6-naphthalene dicarboxylic acid is an important monomer of a variety of high-performance plastics,liquid crystal polymer（LCP）and polyurethane resin.In recent years,with the rapid development of the 5G industry,the demand for high-performance LCP has sharply increased.Therefore,the large-scale preparation of 2,6-naphthalene dicarboxylic acid is crucial for the development of the 5G industry.Using abundant naphthalene as raw material,2,6-dialkylnaphthalene is prepared through alkylation reaction,and the oxidation reaction to prepare 2,6-naphthalene dicarboxylic acid is a highly promising production route.The key to achieving this route is the selective preparation of 2,6-dialkylnaphthalene through naphthalene alkylation.Therefore,this thesis focus on the alkylation reaction of naphthalene and isopropanol,attempting to explore the influence of pore structure and acid properties of molecular sieves on the alkylation reaction of naphthalene and isopropanol,and preparing high-performance molecular sieve catalysts for naphthalene shape selective isopropylation reaction.The research content is as follows:Explore the characteristics of ZSM-5,MOR,Beta,and Y molecular sieves in catalyzing the isopropylation of naphthalene under suitable conditions,and study the catalytic performance of molecular sieves in the alkylation process of naphthalene through gas chromatography.ZSM-5 molecular sieve has the lowest reaction activity,and the increase in temperature and time can significantly affect its conversion rate of alkylated naphthalene and the 2,6-/2,7-DIPN ratio.After the temperature of MOR molecular sieve increased to 250^oC,the conversion rate of naphthalene showed a significant improvement.Although the 2,6-/2,7-DIPN ratio decreased,it still maintained a high ratio above 2.2.After adjusting the appropriate reaction conditions on Beta molecular sieve,the conversion rate of naphthalene is higher at over 80%,and the selectivity of 2,6-DIPN and the 2,6-/2,7-DIPN ratio are slightly improved.Y molecular sieve has the highest degree of catalytic alkylation of naphthalene,with tertiary isopropyl naphthalene and higher isopropyl naphthalene as the main product.The selectivity of 2,6-DIPN is relatively low.We select MOR molecular sieves with excellent comprehensive reaction performance as the focus of subsequent research,and explore the impact of changes in silicon aluminum ratio on MOR catalyzed naphthalene isopropylation reaction.The reaction activity increases with the increase of silicon aluminum ratio.Increasing the temperature can reduce the difference in conversion rates between different silicon aluminum ratios.However,excessive temperature is not conducive to MOR shape selective catalysis.In addition,the effect of time on the reaction is relatively small.A suitable raw material composition is conducive to the alkylation reaction..Based on the study of the characteristics of MOR molecular sieve catalytic naphthalene isopropylation reaction,a simple and feasible method for morphology control of MOR molecular sieve was proposed.During the preparation of MOR,different amounts of hexadecyltrimethylammonium bromide（CTAB）were added to regulate the crystallization process,and MOR molecular sieves with rod-shaped aggregate morphology were successfully prepared.Scanning electron microscopy（SEM）,X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FT-IR）,chemical adsorption analyzer（NH₃-TPD）,and physical adsorption analyzer（BET）were used to analyze the micro morphology,structural composition,and physical and chemical properties of the molecular sieve,demonstrating the mechanism of CTAB addition on MOR molecular sieve morphology regulation.The appropriate amount of CTAB addition improves the catalytic performance of MOR molecular sieves by regulating their morphology.