二氧化氮为硝化剂的苯硝化反应

以溶胶-凝胶法制备的负载型磷钨杂多酸为催化剂,分别在常压和加压条件下,优化了NO_2代替硝酸作为硝化剂的苯液相硝化反应条件。对于常压反应,在m(催化剂):m(苯)=1:12、NO_2气体流速为10 mL/min、O_2流速为5 mL/min、反应时间为8 h、反应温度为60℃的件下,硝基苯收率为29.5%。对于加压反应,适宜的反应条件为:n(NO_2)n(苯)=2.5:1,w(催化剂)=3.5%,O_2初始压力1.0 MPa,反应温度90℃,反应时间6 h。在此条件下,硝基苯收率为41.8%。

STUDY ON BENZENE NITRATION BY NO2

The nitration of benzene by NO_2 instead of nitric acid over H_3 PW_(12) O_(40) / SiO_2 catalyst prepared by a sol-gel technique was conducted separately in an atmosphere reactor and in an autoclave.The experimental results indicated that under the atmospheric conditions,the weight ratio of the catalyst to benzene of 1:12, flowrate of NO_2 10 mL/min,flowrate of O_2 5 mL/min,reaction temperature 60 °C and reaction time 8 h,the yield of nitrobenzene achieved 29.5%,while the yield of nitrobenzene was 41.8% in an autoclave under the conditions of molar ratio of NO_2 to benzene 2.5:1,weight percentage of the catalyst 3.5% ,initial pressure of O_2 1 MPa,reaction temperature 90 ℃ ,and reaction time 6 h.