Process for producing mirbane oil by gas-phase nitration

Abstract

The invention uses benzene and nitric acid as raw materials to prepare nitrobenzene by gas-phase nitration in the presence of a catalyst. The catalyst preparation method is the sol-gel method, and the H2SO4-SiO2 catalyst is prepared with ethyl silicate and sulfuric acid, the sulfuric acid content is 10-75%, the nitration reaction temperature is 140-220 °C, and the molar ratio of the reactant benzene to nitric acid is 1- 4:1, the liquid space velocity is 0.1~10h-1. The H2SO4-SiO2 catalyst has high activity and long service life. During the 1000 hours of catalytic reaction, the catalyst activity remains basically unchanged. The process avoids the use of a large amount of sulfuric acid, has high conversion rate of nitric acid, less free acid in the reaction product, easy separation, less discharge, simple process flow, meets environmental protection requirements, and can realize green production of nitrobenzene.

Description

technical field

[0001] The invention relates to a technology for preparing nitrobenzene by gas-phase nitration of benzene, specifically a method for preparing a solid acid catalyst and carrying out gas-phase catalytic nitration of benzene in a fixed bed to produce nitrobenzene. Background technique

[0002] Nitrobenzene is an important chemical raw material, which can be used as an intermediate for explosives, medicine, pesticides, dyes, etc. The most important use of nitrobenzene is to produce aniline. There are hundreds of downstream products of aniline. At the same time, nitrobenzene itself can also be used as a solvent for chemical reactions. Therefore, nitrobenzene has a huge market demand. At present, the main process of industrial production of nitrobenzene is nitric acid mixed acid method. The mixture of benzene, sulfuric acid and nitric acid reacts under strong stirring to generate nitrobenzene. This process has higher benefits, but this process needs to use a large...

Examples

Embodiment 1

[0019] Weigh 59.67g of ethyl silicate, add 40ml of water, add 12g of 0.05N dilute hydrochloric acid, stir to form a sol, then add 130g of dilute sulfuric acid (30%), stir, leave to stand for two days after 8 hours for aging, and vacuum-dry the obtained gel , to obtain solids, crush and sieve the solids to obtain 40-60 mesh particles, denoted as H 2 SO 4 -SiO 2 . H 2 SO 4 -SiO 2 Put it in an oven at 120°C and keep it for three hours, then raise the temperature to 200°C and keep it for 0.5 hour, take it out and cool it down to get a solid catalyst.

[0020] Get 4ml of the obtained catalyst and put it into the reaction tube, the upper part of the reaction tube is equipped with about 20cm of ceramic discs for the gasification of the raw material, the temperature of the heating furnace is raised to 140 °C, and 65% nitric acid and benzene are pumped in respectively, and the nitric acid feed The flow rate was 2.0 ml / h and the benzene feed flow rate was 5.0 ml / h.

[0021] React...

Embodiment 2

[0027] Same as in Example 1, the temperature of the heating furnace was changed, and the temperature of the heating furnace was raised to 160°C.

[0028] Reaction conditions: Reaction temperature 185°C;

[0029] Liquid space velocity 1.8h -1 ;

[0030] The molar ratio of benzene to nitric acid=2:1;

[0031] Reaction result: nitric acid conversion rate 97.1%;

[0032] The selectivity of nitrobenzene is 98.7%.

Embodiment 3

[0034] As in Example 1, the feed flow rate of benzene was changed, and the feed flow rate of benzene was 2.5ml / h.

[0035] Reaction conditions: Reaction temperature 155°C;

[0036] Liquid space velocity 1.1h -1 ;

[0037] The molar ratio of benzene to nitric acid = 1:1;

[0038] Reaction result: the conversion rate of nitric acid is 87.5%;

[0039] The selectivity of nitrobenzene is 98.5%.

technical field

[0001] The invention relates to a technology for preparing nitrobenzene by gas-phase nitration of benzene, specifically a method for preparing a solid acid catalyst and carrying out gas-phase catalytic nitration of benzene in a fixed bed to produce nitrobenzene. Background technique

[0002] Nitrobenzene is an important chemical raw material, which can be used as an intermediate for explosives, medicine, pesticides, dyes, etc. The most important use of nitrobenzene is to produce aniline. There are hundreds of downstream products of aniline. At the same time, nitrobenzene itself can also be used as a solvent for chemical reactions. Therefore, nitrobenzene has a huge market demand. At present, the main process of industrial production of nitrobenzene is nitric acid mixed acid method. The mixture of benzene, sulfuric acid and nitric acid reacts under strong stirring to generate nitrobenzene. This process has higher benefits, but this process needs to use a large...

Examples

Embodiment 1

[0019] Weigh 59.67g of ethyl silicate, add 40ml of water, add 12g of 0.05N dilute hydrochloric acid, stir to form a sol, then add 130g of dilute sulfuric acid (30%), stir, leave to stand for two days after 8 hours for aging, and vacuum-dry the obtained gel , to obtain solids, crush and sieve the solids to obtain 40-60 mesh particles, denoted as H 2 SO 4 -SiO 2 . H 2 SO 4 -SiO 2 Put it in an oven at 120°C and keep it for three hours, then raise the temperature to 200°C and keep it for 0.5 hour, take it out and cool it down to get a solid catalyst.

[0020] Get 4ml of the obtained catalyst and put it into the reaction tube, the upper part of the reaction tube is equipped with about 20cm of ceramic discs for the gasification of the raw material, the temperature of the heating furnace is raised to 140 °C, and 65% nitric acid and benzene are pumped in respectively, and the nitric acid feed The flow rate was 2.0 ml / h and the benzene feed flow rate was 5.0 ml / h.

[0021] React...

Embodiment 2

[0027] Same as in Example 1, the temperature of the heating furnace was changed, and the temperature of the heating furnace was raised to 160°C.

[0028] Reaction conditions: Reaction temperature 185°C;

[0029] Liquid space velocity 1.8h -1 ;

[0030] The molar ratio of benzene to nitric acid=2:1;

[0031] Reaction result: nitric acid conversion rate 97.1%;

[0032] The selectivity of nitrobenzene is 98.7%.

Embodiment 3

[0034] As in Example 1, the feed flow rate of benzene was changed, and the feed flow rate of benzene was 2.5ml / h.

[0035] Reaction conditions: Reaction temperature 155°C;

[0036] Liquid space velocity 1.1h -1 ;

[0037] The molar ratio of benzene to nitric acid = 1:1;

[0038] Reaction result: the conversion rate of nitric acid is 87.5%;

[0039] The selectivity of nitrobenzene is 98.5%.

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