CN102399154A

CN102399154A - Method for producing methylaniline from nitrotoluene through liquid-phase hydrogenation reduction

Info

Publication number: CN102399154A
Application number: CN201110225430XA
Authority: CN
Inventors: 管政
Original assignee: JIANGSU FIRST CHEMICAL MANUFACTURE CO LTD
Current assignee: JIANGSU FIRST CHEMICAL MANUFACTURE CO LTD
Priority date: 2011-08-08
Filing date: 2011-08-08
Publication date: 2012-04-04

Abstract

The invention discloses a method used for producing methylaniline from nitrotoluene through liquid-phase hydrogenation reduction. The production method of methylaniline comprises steps of feeding reduction and pressure-reducing separation. In the feeding reduction process, methanol, a Raney nickel catalyst, hydrogen and nitrotoluene are added to a reaction vessel; under the existence of both the solvent methanol and the catalyst, a liquid-phase catalyzed hydrogenation reaction is carried out, such that nitrotoluene is produced. According to the invention, the controlling requirements of production indexes such as temperature and pressure are low, and the method is advantaged in easy operation and management, high equipment automatic control level, good product quality, high yield, low energy consumption, recoverable catalyst and methanol, low wastewater generation, low tar, good environmental benefit, low operation cost, and high adaptability. The method can be used in reduction reactions of o-, m- or p-nitrotoluene for producing o-, m- or p-methylaniline.

Description

Nitrotoluene liquid-phase hydrogenatin is the method for original production monomethylaniline also

Technical field

The present invention relates to the working method of monomethylaniline, particularly relate to the also method of original production monomethylaniline of a kind of nitrotoluene liquid-phase hydrogenatin.

Background technology

The technology of reduction of methylaniline from nitro-toluene has the iron powder reducing method that adopts in the prior art, this technology comparative maturity, but it contains a large amount of amine iron mud in process of production and can't handle.Other has a kind of is solvent-free hydrogenating reduction method; Under the condition that catalyzer exists, but do not have any solvent, nitrotoluene gets final product and hydrogen reaction; After reaction is accomplished; Mixed solution and catalyzer filter, leave standstill or dynamic separation, and catalyst recovery is utilized again, and the bullion monomethylaniline can obtain finished product after separation, dehydration, rectifying.The productive capacity of this method such as temperature, pressure etc. require control high, and quality product is good inadequately, and the shelf time is also short partially, and yield is not too high, consume greatlyyer, have problems such as running cost height.By above-mentioned visible, exist many disadvantages in the prior art, the utmost point is necessary to improve.

Summary of the invention

The objective of the invention is to: the also method of original production monomethylaniline of a kind of nitrotoluene liquid-phase hydrogenatin is provided, and the liquid phase catalytic hydrogenation reduction generates monomethylaniline under solvent methanol and the common condition that exists of catalyzer, and the control of productive capacity such as temperature, pressure requires lower, easily operational administrative; Device automatic control level is high, good product quality, and yield is high; Energy consumption is low, and its catalyzer and methyl alcohol are all recyclable to be utilized again, and it is few to produce wastewater flow rate; Tar is few, and environmental benefit is good, and running cost is low; Flexibility is strong, can be used for the neighbour,, the reduction of PNT, produce adjacent,, para-totuidine.

Technical solution of the present invention is: the working method of this monomethylaniline comprises reinforced reduction and release separating step; In reinforced reduction step; In reaction kettle, add methyl alcohol, Raney's nickel catalyst, hydrogen and nitrotoluene; Under solvent methanol and the common condition that exists of catalyzer, the liquid phase catalytic hydrogenation reduction generates monomethylaniline.

Wherein, concrete steps of the present invention are following:

(1) reinforced reduction: the Raney's nickel catalyst after in reaction kettle, adding methyl alcohol and launching; And hydrogen fed in the reaction kettle with the pressure of 1.0～1.2MPa, with the air displacement in the reaction kettle fully after, start agitator motor; Its rotating speed is controlled at 300～345r.p.m; Again to reaction kettle heating, simultaneously with the Raney's nickel catalyst of nitrotoluene with methyl alcohol, after launching in 200:200: the ratio of (4～5) progressively adds in the reaction kettle, begins in the still to react; Reactor temperature is controlled at 80～90 ℃, reacts after 3～4 hours to the reaction end;

(2) release separates: the temperature of reaction kettle is reduced to 50 ± 5 ℃ of releases; When pressure only has 0.3～0.4MPa, analyze nitro thing content qualified after; Open the binder valve, thick monomethylaniline is depressed into the bullion groove, leaves standstill, make it and catalyst separating; Catalyst recovery is utilized again, and reaction kettle is suction again, intensification, driving again;

(3) subsequent step: thick monomethylaniline is obtained the monomethylaniline finished product through eparating methanol tower separating methanol, dehydration tower dehydration, rectifying tower rectifying respectively.

Advantage of the present invention is: 1, the control of productive capacity such as temperature, pressure requirement is lower, and operational administrative installs automatic control level height easily; 2, good product quality, yield is high, and energy consumption is low, and catalyzer and methyl alcohol are all recyclable to be utilized again; 3, the generation wastewater flow rate is few, and tar is few, and environmental benefit is good; 4, running cost is low, and flexibility is strong, can be used for the neighbour,, the reduction of PNT, produce adjacent,, para-totuidine.

Description of drawings

Fig. 1 is a Production Flow Chart block diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing technical solution of the present invention is elaborated as follows, the present invention is an intermittent operation, and these embodiment just are used to understand technical solution of the present invention, rather than to the restriction of technical solution.

Embodiment 1: is 5m through pipeline to volume ³In the reaction kettle, add solvent methanol 2000Kg, add the unfolded Raney's nickel catalyst through pipeline simultaneously; Will add 40Kg when driving first, every still only need be added 2Kg when treating its ordinary production, feeds hydrogen through pipeline; And hydrogen pressure machine top hole pressure reconciled to 1.0MPa; After making the interior air displacement of reaction kettle fully, start agitator motor, the control rotating speed is that 320r.p.m heats up; When temperature of reaction kettle is heated to 55 ℃, with volume pump the purity that is up to the standards is not less than 99% 2000Kg meta-nitrotoluene through pipeline and progressively adds and begin reaction in the still; Close heating steam, open cooling water valve, temperature is controlled at 80～90 ℃, react after 3～4 hours,, when temperature no longer rises, show that reaction finishes basically when reaction kettle pressure rises; At this moment close intake valve pressurize for some time of hydrogen, so that a small amount of unreacted nitro thing continues reaction; When finding that temperature of reaction kettle descends very slowly, do not see variation in 15 minutes, show that reaction finishes; Open cooling water temperature to 50 ± 5 ℃, release, when pressure only has 0.3～0.4MPa, analyze nitro thing content qualified after, open the binder valve; Thick meta-aminotoluene is depressed into the bullion groove, leaves standstill; Make it and catalyst separating, catalyst recovery is utilized again, reaction kettle suction again, intensification, driving; Last thick para-totuidine respectively through eparating methanol tower separating methanol, dehydration tower dehydration, rectifying tower rectifying, gets the meta-aminotoluene finished product again.

Embodiment 2: is 5m through pipeline to volume ³In the reaction kettle, add solvent methanol 2000Kg, add the unfolded Raney's nickel catalyst through pipeline simultaneously; Will add 45Kg when driving first, every still only need be added 2Kg when treating its ordinary production, feeds hydrogen through pipeline; And hydrogen pressure machine top hole pressure reconciled to 1.1MPa; After making the interior air displacement of reaction kettle fully, start agitator motor, the control rotating speed is that 330r.p.m heats up; When temperature of reaction kettle is heated to 55 ℃, with volume pump the purity that is up to the standards is not less than 99% 2000Kg PNT through pipeline and progressively adds and begin reaction in the still; Close heating steam, open cooling water valve, temperature is controlled at 80～90 ℃, react after 3～4 hours,, when temperature no longer rises, show that reaction finishes basically when reaction kettle pressure rises; At this moment close intake valve pressurize for some time of hydrogen, so that a small amount of unreacted nitro thing continues reaction; When finding that temperature of reaction kettle descends very slowly, do not see variation in 15 minutes, show that reaction finishes; Open cooling water temperature to 50 ± 5 ℃, release, when pressure only has 0.3～0.4MPa, analyze nitro thing content qualified after, open the binder valve; Thick para-totuidine is depressed into the bullion groove, leaves standstill; Make it and catalyst separating, catalyst recovery is utilized again, reaction kettle suction again, intensification, driving; Last thick para-totuidine respectively through eparating methanol tower separating methanol, dehydration tower dehydration, rectifying tower rectifying, gets the para-totuidine finished product again.

Embodiment 3: is 5m through pipeline to volume ³In the reaction kettle, add solvent methanol 2000Kg, add the unfolded Raney's nickel catalyst through pipeline simultaneously; Will add 50Kg when driving first, every still only need be added 2Kg when treating its ordinary production, feeds hydrogen through pipeline; And hydrogen pressure machine top hole pressure reconciled to 1.2MPa; After making the interior air displacement of reaction kettle fully, start agitator motor, controlling its rotating speed is that 345r.p.m heats up; When temperature of reaction kettle is heated to 55 ℃, with volume pump the purity that is up to the standards is not less than 99% 2000Kg Ortho Nitro Toluene through pipeline and progressively adds and begin reaction in the still; Close heating steam, open cooling water valve, temperature is controlled at 80～90 ℃, react after 3～4 hours,, when temperature no longer rises, show that reaction finishes basically when reaction kettle pressure rises; At this moment close intake valve pressurize for some time of hydrogen, so that a small amount of unreacted nitro thing continues reaction; When finding that temperature of reaction kettle descends very slowly, do not see variation in 15 minutes, show that reaction finishes; Open cooling water temperature to 50 ± 5 ℃, release, when pressure only has 0.3～0.4MPa, analyze nitro thing content qualified after, open the binder valve; Thick Ortho Toluidine is depressed into the bullion groove, leaves standstill; Make it and catalyst separating, catalyst recovery is utilized again, reaction kettle suction again, intensification, driving; Last thick Ortho Toluidine respectively through eparating methanol tower separating methanol, dehydration tower dehydration, rectifying tower rectifying, gets the Ortho Toluidine finished product again.

Claims

1. the nitrotoluene liquid-phase hydrogenatin method of original production monomethylaniline also; It is characterized in that: the working method of this monomethylaniline comprises reinforced reduction and release separating step; In reinforced reduction step; In reaction kettle, add methyl alcohol, Raney's nickel catalyst, hydrogen and nitrotoluene, under solvent methanol and the common condition that exists of catalyzer, the liquid phase catalytic hydrogenation reduction generates monomethylaniline.

2. nitrotoluene liquid-phase hydrogenatin according to claim 1 is the method for original production monomethylaniline also, it is characterized in that: the working method of this monomethylaniline comprises following concrete steps:

(3) postorder is refining: thick monomethylaniline is obtained the monomethylaniline finished product through eparating methanol tower separating methanol, dehydration tower dehydration, rectifying tower rectifying respectively.