CN1087970C

CN1087970C - Preparation and use method of catalyst for synthesis of 2,6-dimethylaniline

Info

Publication number: CN1087970C
Application number: CN97108179A
Authority: CN
Inventors: 刘智凌; 廖文文; 王宇; 谭卫宁; 陈平; 邹德元
Original assignee: Hunan Research Institute of Chemical Industry
Current assignee: Hunan Research Institute of Chemical Industry
Priority date: 1997-08-06
Filing date: 1997-08-06
Publication date: 2002-07-24
Anticipated expiration: 2017-08-06
Also published as: CN1207329A

Abstract

The present invention discloses the preparation and a use method of a catalyst for synthesizing 2, 6-dimethylaniline. The preparation comprises: r-Al2O3 is used as a carrier skeleton and leached in a solution of Mg(NO3)2.6H2O and Al(NO3)3 to obtain a spinel type Al2O3-MgO carrier, and the spinel type Al2O3-MgO carrier is immersed in a solution of PdCl2 and hydrochloric acid to prepare the catalyst Pd/Al2O3-MgO/Al2O3. The prepared catalyst is loaded into a stainless steel pipe, and both ends of the stainless steel pipe are filled with ceramic rings; the stainless steel pipe is heated with resistance wires, and 2, 6-xylenol, hydrogen and ammonia are introduced into the stainless steel pipe under normal pressure so as to prepare 2, 6-dimethylaniline. The use method has the advantages of simple preparation process and convenient operation; during the catalytic synthesis of 2, 6-dimethylaniline, the catalyst has high activity, good intensity and long service life, and the product has good selectivity and high yield.

Description

Synthetic 2, the Preparation of catalysts of 6-dimethylaniline and application process

The present invention relates to a kind of Preparation of catalysts method that is used for Synthetic 2 .6-dimethylaniline and be used for Synthetic 2, the method for 6-dimethylaniline.

2.6-dimethylaniline is important meticulous organic chemical industry's intermediate, is mainly used in to produce agricultural chemicals, dyestuff and medicine, wherein commercial have bactericide, herbicide, an anesthetic etc.2.6-the early stage production method of dimethylaniline is a meta-xylene restore nitrification method, with the concentrated sulfuric acid, nitric acid nitrating and iron powder reducing, has a large amount of three wastes to produce; After be improved to hydrogenating reduction or electrochemical reduction, but principal product 2, the 4-dimethylaniline has restricted development (United States Patent (USP) U.S.P.3,965,182 of this process route; U.S.P.3,960,962; U.S.P.3,931298 etc.), adopt 2,6-xylenol liquid-phase catalysis amination Synthetic 2,6-dimethylaniline, and industrialization.European patent E.P.68 in 282 and Deutsche Bundespatent D.E.3,147,734, adopts Al ₂O ₃Be catalyst, 400 ℃ of 90 crust descends 2,6-xylenol gas phase catalysis amination preparation 2,6-dimethylaniline.Europe another piece patent E.P.53,817; E.P.53,819 adopt spinelle Al ₂O ₃-MgO is a carrier, and load 0.5% Metal Palladium is a catalyst, at 180 ℃-200 ℃, normal pressure, and by 2,6-xylenol gas phase catalysis preparation 2,6-dimethylaniline, product selectivity about 70%, but above all unexposed Preparation of catalysts method.

The purpose of this invention is to provide a kind of Synthetic 2 that is used for, gas phase Study on Catalytic Amination of Alcohols preparation 2 under the Preparation of catalysts method of 6-dimethylaniline and the normal pressure, the method for 6-dimethylaniline.

Task of the present invention is finished like this: take by weighing r-Al earlier ₂O ₃,,, take by weighing Mg (NO again as carrier framework 200 ℃ of dehydrations down ₃) ₂6H ₂O joins Al (NO ₃) ₃Dissolve in the solution, pour this solution into dress r-Al ₂O ₃In the burning of the carrier framework bosom, incipient impregnation, then 120 ℃ dry down, 800-1300 ℃ of roasting 6 hours obtains sharp crystal Al after the cooling ₂O ₃-MgO carrier; Take by weighing NaHCO again ₃Wiring solution-forming, impregnated carrier again, 120 ℃ of following dried overnight; Take by weighing PdCl at last ₂, to dissolve by 1+10 with watery hydrochloric acid, dissolving back and above-mentioned carrier incipient impregnation, the drying that makes obtain catalyst P d (0.5% weight)/Al ₂O ₃-MgO (4: 1 weight)/Al ₂O ₃With the catalyst that the makes internal diameter of packing into is in the stainless steel tube of φ 19mm, uses the resistance wire heating, and managing built-in external diameter is the thermocouple temperature measurement sleeve pipe of 6mm, catalyst loads the porcelain ring up and down, and normal pressure feeds 2 down, 6-xylenol, hydrogen, ammonia, catalyst loading is a 0.1-0.15 gram 2,6-xylenol/gram catalyst hour, reaction temperature 180-200 ℃, 2,6-xylenol conversion ratio reaches 97.9%, 2.6-dimethylaniline selectivity 74.3%, 2,6-dimethyl cyclohexyl amine selectivity is 2.52%.

Preparation technology of the present invention is simple, and raw material is easy to get, and is easy to operate, is being used for Synthetic 2, when the 6-dimethylaniline synthesizes, and the catalyst activity height, intensity is good, and the life-span is long, reaction condition gentleness, selectivity of product height.

The invention will be further described below in conjunction with embodiment:

Embodiment 1:

Take by weighing 25 gram φ 3mm * 5mmr-Al ₂O ₃, at 200 ℃ of following drying and dehydratings, be placed on as carrier framework and burn in the bosom standbyly, take by weighing 3.205 gram Mg (NO ₃) ₂6H ₂O joins 25.18 gram Al (NO ₃) ₃(contain Al in the solution ³⁺Be 4.1%) dissolving.Solution poured into r-Al is housed ₂O ₃Burning cherish medium volume dipping, 120 ℃ of following dried overnight reduce nitrate under 300 ℃, then 900 ℃ of following roastings 6 hours, after the cooling spinelle Al ₂O ₃-MgO carrier 27g takes by weighing 1.25 gram NaHCO then ₃Be made into 10ml solution, dipping, 120 ℃ of following dried overnight.Take by weighing PdCl again ₂0.209 gram adds watery hydrochloric acid 10ml, dissolves, dissolving back and the 27 gram carrier impregnation that obtain earlier are washed with distilled water to no chlorion and sodium ion then, and be dry again, thereby make catalyst 20g, carries palladium amount 0.5% (weight), surfaces A l ₂O ₃: MgO=4: 1 (weight), surfaces A l ₂O ₃+ MgO pickup is 10%.

With the catalyst 20g that makes, in the internal diameter φ 19mm stainless steel tube of packing into, with the resistance wire heating, managing built-in external diameter is the thermocouple temperature measurement sleeve pipe of 6mm, and catalyst loads the porcelain ring up and down.Under the normal pressure, 2, the 6-xylenol carries out being 3.0g/hr, ammonia and hydrogen flow rate all are 80ml/min, 195 ℃ of reaction temperatures, 2,6-xylenol conversion ratio 97.9%, 2,6-dimethylaniline selectivity 74.3%, 2,6-dimethyl cyclohexyl amine selectivity is 25.2%.

Embodiment 2

Catalyst preparation process is with embodiment 1, Al ₂O ₃The total pickup of+MgO is 8%, and 180 ℃ of reaction temperatures, in 2.0 gram/times of charging, other reaction condition is constant, 2, and 6-xylenol conversion ratio 96.39%, 2,6-dimethylaniline selectivity 24.91%, 2,6-dimethyl cyclohexyl amine selectivity 74.85%.

Embodiment 3

Catalyst is with embodiment 2,180 ℃ of reaction temperatures, charging 2.0 gram 2.6-xylenols/hour, hydrogen flowing quantity is 80 ml/min, ammonia flow is 40 ml/min, 2,6-xylenol conversion ratio 99.07%, 2,6-dimethylaniline selectivity 32.70%, 2,6-dimethyl cyclohexyl amine selectivity 66.20%.Embodiment 4:

Preparation of Catalyst is with embodiment 1, but 1050 ℃ of carrier sintering temperatures, loading catalyst 20 grams, 180 ℃ of reaction temperatures, 2,6-xylenol inlet amount 3.0 Grams Per Hours, ammonia and hydrogen flowing quantity are respectively 60 ml/min and 80 ml/min, 2,6-xylenol conversion ratio 96.72%, 2,6-dimethylaniline selectivity 40.20%, 2,6-dimethyl cyclohexyl amine selectivity 59.30%.

Embodiment 5:

The same embodiment of Preparation of Catalyst, but 1300 ℃ of carrier sintering temperatures, the aminating reaction condition is with embodiment 4,2,6-xylenol conversion ratio 65.72%, 2,6-dimethylaniline selectivity 20.3%, 2,6-dimethyl cyclohexyl amine selectivity 78.50%.

Claims

1, a kind of Synthetic 2 that is used for, the Preparation of catalysts method of 6-dimethylaniline is characterized in that: take by weighing r-Al ₂O ₃At 200 ℃ of following drying and dehydratings,, take by weighing Mg (NO again as carrier framework ₃) ₂6H ₂O and Al (NO ₃) ₃Wiring solution-forming is with solution and r-Al ₂O ₃Incipient impregnation, then 120 ℃ down dry, 800 ℃～1300 ℃ roastings 6 hours obtain spinelle Al after the cooling ₂O ₃-MgO carrier takes by weighing NaHCO again ₃Wiring solution-forming, impregnated carrier again, 120 ℃ of following dried overnight take by weighing PdCl at last ₂, to dissolve by 1+10 with watery hydrochloric acid, dissolving back and the above-mentioned carrier incipient impregnation that makes are washed with distilled water to no chlorion and sodium ion then, and be dry again, obtains catalyst P d (0.5% weight)/Al ₂O ₃-MgO (4: 1 weight)/Al ₂O ₃

2, a kind of catalyst Synthetic 2 that utilizes according to claim 1 preparation, the method of 6-dimethylaniline, it is characterized in that: the catalyst that makes is packed in the stainless steel tube, the heating of use resistance wire, pipe built-in thermoelectric idol temperature-measuring casing, catalyst loads the porcelain ring up and down, normal pressure feeds 2 down, 6-xylenol, ammonia and hydrogen, catalytic reaction Synthetic 2,6-dimethylaniline, 180～200 ℃ of reaction temperatures, hydrogen and ammonia flow velocity are 40ml/min-80ml/min, 2, and the inlet amount of 6-xylenol is 2～3g/hr.