Study on catalytic synthesis of xylene using methyl bromide as methylation agent

• 1、College of Chemistry and Chemical Engineering,Hunan University
• 2、College of Chemistry and Chemical Engineering,Hunan University,Changsha 410082
• 3、College of Chemistry and Chemical Engineering,Hun University,Changsha 410082
• 4、College of Chemisrty and Chemical Engineering,Hunan University,Changsha 410082

Abstract：In order to achieve an effective use of natural gas resources to get higher value-added aromatics products, we examined the catalytic synthesis of xylene by methylation of toluene using methyl bromide as methylation agent in the presence of ZSM-5 zeolite on a fixed-bed reactor. The effects of SiO2/Al2O3 ratio, reaction temperature, weight hourly space velocity of toluene and toluene/CH3Br molar ratio on toluene conversion and xylene yield were systematically investigated. The yield of xylene is up to 29.3% under the optimal reaction condition (SiO2/Al2O3 ratio, reaction temperature, weight hourly space velocity and toluene/CH3Br molar ratio are 100, 400oC, 0.46h-1 and 1, respectively). CH3Br as methylation agent is more effective than methanol for the methylation of toluene into xylene. Furthermore, p-xylene selectivity in xylene is higher than the thermodynamic equilibrium value after the HZSM-5 molecular sieve catalysts are modified by Mg, B or P compound.

Keywords： industral catalysis CH3Br toluene HZSM-5 methylation xylene