CN1005149B - Manufacture of tetra-chloro-m-phthalonitrile by chlorination of m-phthalonitrile - Google Patents

Abstract

The present invention relates to a composite bed reactor for connecting a fixed bed with a fluidized bed in series. M-phthalodinitrile is vaporized, mixed with chlorine and hydrogen chloride or nitrogen, supplied into a fluidized-bed reactor and primarily chlorinated by a technological method for preparing tetra-chloro-m-phthalonitrile by chlorination of m-phthalonitrile; the mixed gas reaching certain conversion rate is then supplied into a fixed-bed reactor and finally chlorinated. The produced tetra-chloro-m-phthalonitrile is condensed and collected. The hydrogen chloride or the nitrogen as diluent gas can be partially recycled after tail gas is separated and treated, the total yield of the tetra-chloro-m-phthalonitrile is more than 95 %, and the present invention can stably operate for a long term.

Description

Manufacture of tetra-chloro-m-phthalonitrile by chlorination of m-phthalonitrile

The invention belongs to the production method of sterilant termil.

The present invention adopts novel reactor-multiple-hearth to be made the production method of sterilant termil by the Isophthalodinitrile gas phase catalysis.

The chlorination of Isophthalodinitrile gas phase catalysis is the irreversible cascade reaction of a kind of heat effect big (generating hot 103 kcal/mol), and reaction is particularly fierce early stage, thermal discharge concentrate (when reacting 2～3 seconds, with emit net quantity of heat 70～80%).Therefore, for this reaction, if only adopt single fixed-bed reactor.As: U.S. patent 3652637, day special permission 43-22298 and special permission 43-22589.Because the inherent shortcoming of fixed bed own is that heat conductive efficiency is low, local heating will appear in bed, i.e. focus, even cause temperature runaway, out of control, final sintered catalyst layer, cause shut-down.Day special permission 43-22298 is connected in Primary Catalysts layer front with spent catalyst, and the way of two-stage reaction prolongs the work-ing life of Primary Catalysts.But, all be the fixed-bed reactor of usefulness, the limited time of first section used spent catalyst, the very fast also entail dangers to of the load of chlorination reaction be to the work-ing life as second section Primary Catalysts, brought caused drawback when only adopting one section fixed-bed reactor equally.And it is unlikely excessive that the Primary Catalysts layer is loaded, and prolongs life certainly will frequently be changed the catalyzer that gives that had lost efficacy.As everyone knows, removing stage makeup and costume of fixed bed catalyst is the thing of the very heavy trouble of part, and frequent replacing also can reduce on-stream time.United States Patent (USP) 3839401 reports adopt single fluidized-bed reactor to finish this reaction.Because fluidized-bed, the concentration of the back-mixing of bed inner catalyst particle and air-flow, the material concentration of reactor exit and inside reactor is suitable, reach higher transformation efficiency, and catalyst consumption certainly will increase.For this reason, according to dynamic characteristic research and the short characteristics of catalyst life to this reaction; In conjunction with after fixed bed and fluidized-bed relative merits are separately done to analyze relatively fully, we adopt fluidized-bed and the combined reactor types of fixed bed again, and promptly multiple-hearth is finished this chlorination reaction.It is low that it has avoided fixed-bed heat transfer usefulness, and this chlorination reaction is caused that easily sintering stops up and the shortcoming of catalyst loading and unloading difficulty.Avoided the fluidized-bed transformation efficiency and be not so good as the fixedly shortcoming of the height of bed, and given full play to fluid-bed heat transfer usefulness height, temperature distribution homogeneous in the bed, be difficult for stopping up, catalyst loading and unloading is advantage easily, has brought into play the fixed-bed conversion rate than the fluidisation height of bed, the advantage of good product quality.Reactor types after such combination obviously is better than only adopting the reactor of single type, has adapted to the characteristics and the requirement of this chlorination reaction admirably.

Main points of the present invention: accompanying drawing 1 is a process flow sheet of the present invention.Isophthalodinitrile adds vaporizer (2) by pipeline (1), the hydrogen chloride gas of pipeline (15) or nitrogen carrier gas vaporization Isophthalodinitrile mix with chlorine and circulation carrier gas hydrogenchloride or the nitrogen by pipeline (16) that pipeline (3) comes, the mol ratio of Isophthalodinitrile and chlorine is in 6～12 scopes, enter fluidized-bed (4) under the linear speed self-fluidized type bed grid distributor with 0.18～0.3 meter per second, in the bed catalyzer is housed, 280～360 ℃ of temperature of reaction, in bed, carry out the first step reaction, fluidized-bed (4) outlet transformation efficiency maintains 50～75% scopes, mixed gas after pipeline (5) enters cyclonic separator (6) separating most catalyst dust, through pipeline (7) with 800 o'clock ^-1～400 o'clock ^-1Air speed enter calandria type fixed bed reactor (8), carry out the chlorination of final stage.Catalyzer is housed in the fixed bed, 300～360 ℃ of temperature of reaction, the mixed gas that comes out from fixed-bed reactor (8), enter collector (10) through pipeline (9), behind the condensation collection product termil, take out from pipeline (11), to exhaust treatment system (13), do the Isophthalodinitrile carrier gas and make the fluidized-bed carrier gas through pipeline (16) through pipeline (15) through the circulation of pipeline (14) part again by the nitrogen behind hydrogenchloride behind the separation and recovery of chlorine or separation and recovery of chlorine and the hydrogenchloride through pipeline (12) for remaining gas.Fixed bed outlet transformation efficiency＞98% of pipeline (9).Termil molar yield＞95% that pipeline (11) comes out, tetrachloride content＞98%.

The present invention has following characteristics: owing to adopt fluidized-bed and fixed bed tandem reactor, its turndown ratio is big, fluidized-bed outlet transformation efficiency fluctuates in 42%～90% scope, fixed bed outlet transformation efficiency all can remain on more than 98%, in the early stage that thermal discharge is concentrated, fluidized-bed reactor has been adopted in reaction, thereby the heat conductive efficiency height, good product quality.The U.S.'s 3839401 patent products obtained therefrom termils are 96%, and the present invention is more than 98%, and the U.S. patent of unreacted Isophthalodinitrile is lower than 0.5%, and the present invention does not then have unreacted Isophthalodinitrile at all in product, have only the trichloride of minute quantity.U.S. patent total recovery reaches 94%, and total recovery of the present invention＞95% can the running of long period continous-stable.Because the chlorination of fluidized-bed part is adopted in the front, reduced the load of back fixed bed.The life-span of fixed bed catalyst is very long, the way that fluid catalyst takes regularly part to change, and the cycle of operation of entire equipment is equivalent to the life-span of fixed bed catalyst.

In order to keep fluidized-bed outlet transformation efficiency in 50～75% scopes, regularly (as per 8 hours or 24 hours) carry out exchange to catalyzer, promptly blow out a part of catalyzer, add the raw catalyst of same quantity again.

This composite bed reactor is not only applicable to the chlorination of Isophthalodinitrile, and is suitable for the chlorination of other isomer such as the ortho para benzene dicarbonitrile of benzene dicarbonitrile.Except that above-mentioned chemical manufacturing, it is big mainly to be suitable for thermal discharge, and especially early stage, the exothermic heat of reaction amount was comparatively concentrated.It is few to pay reaction, and the reaction times is longer, and catalyst life is shorter, need the often chemical reaction of replacing, as the production of triphosphazene, by the acetylene preparing chloroethylene, with production, adopt this composite bed reactor form also to suit by acetylene, acetic acid preparing vinyl acetate.

Claims (1)

1, a kind of method that adopts composite bed reactor by Isophthalodinitrile gas phase catalysis chlorination system termil is characterized in that mixing with chlorine and carrier gas after the Isophthalodinitrile gasification.Wherein, the mol ratio of chlorine and Isophthalodinitrile is between 6～12.Linear velocity with 0.18～0.3 meter per second enters fluidized-bed, finishes the part chlorination under 280～360 ℃ temperature, and the transformation efficiency of control fluidized-bed outlet enters fixed-bed reactor then between 50%～75%, 300～360 ℃ temperature, and 800 o'clock ^-1～400 o'clock ^-1Under proceed chlorination reaction, total molar yield of its termil reaches more than 95%, tail gas is through separating to such an extent that hydrogenchloride or nitrogen return as carrier gas and recycles.

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