Ortho-selective Methylation Of Phenol With Methnol

With nitrogen as the carrier gas,ortho-selective vapour phase methylation of phenol with methanol has been continuously carried out in this thesis over self-developed Fe-Mg-O catalyst in a fixed-bed,down flow reactor.Catalytic preparation and its modification,the reaction art and separation process have been studied systematically in the lab-scale experiments of phenol methylation.The research mainly focus on the effect of the reaction temperature,the ratio of feedbacks as well as liquid hourly space velocity.In addition,the reaction and separation technology have also been optimized.It is should be mentioned is that 8 ml,80 ml and 1000 ml gradual enlargement test results are in agreement each other.At the optimal conditions,i.e.,temperature between 350 and 380 ?,the ratio of raw materials for phenol:methanol:water = 1:2:2(molar ratio)and liquid hourly space velocity 0.8-1.0 h"1 at atmospheric pressure,phenol conversion reach as high as 40%with the 90%selectivity of head product o-cresol and 99%total selectivity of o-cresol and dimethyl phenol.This catalyst exerts good replicability and can be regenerated easily;long duration(800 h)continuous operation indicates that no significant deactivation of this catalyst occurred during the reaction.Pilot-scale(5 L)tests further validate the previous results of lab-scale tests,and provide the basis data and theoretical foundation for this project industrialization.Results show that:(1)this catalyst performs excellent stability,obtains 99%selectivity of o-cresol;(2)this catalyst has excellent stability without carbon deposition;(3)this catalysts could tolerate a broader range of reaction temperature,occasional over-temperature has margin affect for catalytic activity and stability;(4)the optimized reaction temperature is between 350 and 365 ?,when reaction temperature for a long time is over 365 ?,the selectivity of o-cresol would decline and methanol decomposition would be enhanced,at certain degree also accelerate catalyst deactivation;(5)compared with the results of available literatures,the performance of this catalyst came up to,even surpass advanced world standard in activity and stability.