CN102936232A - Technology for improving recycling rate of dimethyl formamide (DMF) in production process of fluorescent brightener CBS - Google Patents

Abstract

The invention discloses a technology for improving a recycling rate of dimethyl formamide in the production process of fluorescent brightener CBS, belongs to the technical field of fluorescent brighteners which are used in industrials of printing and dyeing, detergent and soap and aims at solving problems that production costs are high and CBS product solvent residues are high in prior art. The technology includes the following steps of using N, N-DMF as a condensation system original solvent, cooling the N, N-DMF to the temperature of 0-20 DEG C after the condensation reaction is finished, keeping warm for 1-2 hours, and crystallizing most of the CBS; using a centrifugal machine for separation, and washing and drying centrifugal filter cakes; subjecting a centrifuged organic filtering liquid to simple distillation, and separating a mixed fraction of the reaction solvent DMF and methyl alcohol and precipitated CBS; and subjecting the mixed fraction to rectification, separating and purifying the methyl alcohol and the DMF, and subjecting the CBS to salting out, refining and drying to obtain a semi-finished product of the CBS. According to the technology, the recycling rate is improved, and energy consumption and production costs in the process of simple distillation are reduced.

Description

A kind of technique that improves DMF recovery in the fluorescent brightener CBS production process

Technical field

The invention belongs to the white dyes technical field that the industries such as printing and dyeing, washing composition, soap are used, relate to the synthetic method with solvent recuperation of fluorescent brightener CBS, be specifically related to a kind of technique that DMF reclaims in the fluorescent brightener CBS production process that improves.

Background technology

White dyes 4,4 '-two-(2-sodium sulfonate styryl) biphenyl, be called for short CBS, succeeded in developing at the end of the sixties in last century by former Switzerland vapour bar-Jia Ji (existing Ciba) company at first, original process adopts the biphenyl method, and through improving, reaction system original solvents dimethyl sulfoxide (DMSO) (DMSO) is gradually by N, dinethylformamide (DMF) replaces, and is accepted by large multiple enterprises and use.At present in the CBS biphenyl method synthesis and production process process, in the complete system of condensation reaction, except products C BS, also include a large amount of reaction solvent methyl alcohol and DMF, produce an important part in the synthesis technique so the recycling of solvent also becomes.

For solvent residual in the system, all be extensively to adopt first simple distillation that organic solvent methyl alcohol, DMF and the products C BS that contains in the reaction system separated both at home and abroad at present, then through rectification process methyl alcohol and DMF mixed solution are carried out separating-purifying.In service in actual production, whole methyl alcohol and most of DMF can be from the system fractionation by distillation, when distilling near terminal point, residual solvent can't be separated with products C BS with vacuum tightness by the control distillation temperature, solvent still can be residual can't continue to separate to the 40-45% of CBS quality in the still kettle, causes solvent recovering rate low.Remain in the solvent in the still kettle, a place to go is to remain in the CBS product, and the residual CBS product of high solvent can cause bad impact to product applications such as follow-up printing and dyeing, washing composition; Another place to go is to enter waste water system with the refining step of saltouing, and forms high-COD waste water, brings the difficult problem of wastewater treatment.

The above CBS product solvent recovering rate that reflects is low, the problems such as difficult of dissolvent residual and waste water have all restricted the fast development of CBS manufacturing enterprise to a great extent.Therefore, break through the bottleneck that the development of present CBS manufacturing enterprise runs into, the recovery of setting about improving solvent DMF improves CBS product dissolvent residual and wastewater problem, and the development of CBS product industry is had very important meaning.

Summary of the invention

The present invention is the problem that production cost is high, CBS product dissolvent residual is high that exists in order to solve prior art, and a kind of technique that DMF reclaims in the fluorescent brightener CBS production process that improves is provided.

The present invention is achieved by the following technical solutions:

A kind of technique that improves DMF recovery in the fluorescent brightener CBS production process may further comprise the steps:

,, the condensation body that reacts completely is tied up to be cooled to 0-20 ℃ in the reactor first after condensation reaction is finished as condensation system original solvents with DMF DMF, be incubated 1-2 hour, so that most of CBS in the condensation system is crystallized out;

Then enter whizzer the CBS that crystallization in the condensation system goes out is separated from reaction solvent, isolated centrifugal filter cake directly refining washing is dry, obtains the CBS work in-process;

The centrifugal organic filtrate that goes out is processed through simple distillation first, isolates the mixed fraction of reaction solvent DMF and methyl alcohol and the CBS that separates out;

Mixed fraction, with methyl alcohol and DMF separation and purification and is recycled through further rectification process, and the CBS that distillation is separated out is refining dry through saltouing, and obtains the work in-process of CBS.

Further, described whizzer is the sealing hanging bag type centrifugal machine, the quality of control centrifugal filter cake solid content 〉=80%.

The present invention carries out corresponding improvement on original technique basis, first the condensation body that reacts completely is tied up to and be cooled to 0-20 ℃ in the reactor, be incubated 1-2 hour, so that most of CBS in the system is crystallized out, then entering whizzer separates the CBS that crystallization in the system goes out from reaction solvent, isolated centrifugal filter cake need not saltoutd, directly the dry CBS work in-process that obtain of refining washing; The centrifugal organic filtrate that goes out is then processed through simple distillation first, isolates the mixed fraction of reaction solvent DMF and methyl alcohol and the CBS that separates out; Mixed fraction is through further rectification process, can be with methyl alcohol and DMF separation and purification, and recycling; The CBS that distillation is separated out then needs through saltouing refining dry, obtains at last the work in-process of CBS.Because dissolvent residual reduces greatly in the CBS filter cake that centrifugation obtains, also contain certain proportion methyl alcohol in the simultaneously residual solvent, can directly make with extra care does not need salt adding to saltout, the product dissolvent residual that so not only obtains is low, and the waste water saltiness of follow-up generation and COD value are all well below former processing wastewater.

The organic solvent that the present invention is applicable in the fluorescent brightener CBS production process reclaims, and compared with prior art, under the prerequisite that guarantees quality product and yield, residual solvent DMF rate of loss reduces more than 25%, and the rate of recovery also is significantly improved; And because the CBS that direct centrifugation goes out no longer participates in distillation and saltouts, also just having reduced the energy expenditure in the simple distillation process, the throwing salt amount of production also can decrease more than 45%, greatly reduces production cost.

Description of drawings

Fig. 1 is process flow diagram of the present invention.

Embodiment

Embodiment 1

For the complete system of reaction that contains CBS 660Kg, DMF 2400 Kg, methyl alcohol 600 Kg, use circulating frozen salt solution to cool to 12 ℃, behind the insulation 1.5hr, directly enter sealing gallus-type whizzer and carry out centrifugation, after charging stopped, then the 5min that runs up again stopped discharging.Filtrate enters the still kettle distillation by feed pump, and filter cake directly carries out carrying out washing treatment.Filter cake solid content 84%, weight be 410 Kg altogether, and residual organic solvent 78 Kg(wherein DMF are 58.5), last residual 105 Kg of DMF lose DMF 163.5 Kg altogether in the still kettle, and producing simultaneously high salt high-COD waste water amount is 1.3t.As directly entering distillation tower by original technological reaction system, residual 277 Kg of DMF in the last still kettle, producing high salt high-COD waste water amount is 2.7t.After adopting patent of the present invention, residual minimizing 113.5 Kg of DMF, the Direct Loss rate reduces by 40.97%, thereby has guaranteed the efficient recovery of DMF, and high salt high-COD waste water amount has also reduced 1.4t simultaneously.

Embodiment 2

A kind of technique that improves DMF recovery in the fluorescent brightener CBS production process, step is:

For the complete system of the reaction that contains CBS, DMF, methyl alcohol, after condensation reaction is finished, the condensation body that reacts completely is tied up to be cooled to 0 ℃ in the reactor first, be incubated 1-2 hour, so that most of CBS in the system is crystallized out;

Then enter the sealing hanging bag type centrifugal machine, the CBS that crystallization in the condensation system is gone out separates from reaction solvent, and the quality of control centrifugal filter cake solid content 〉=80%, isolated centrifugal filter cake directly refining washing are dry, obtain the CBS work in-process;

The centrifugal organic filtrate that goes out is processed through simple distillation first, isolates the mixed fraction of reaction solvent DMF and methyl alcohol and the CBS that separates out;

Mixed fraction, with methyl alcohol and DMF separation and purification and is recycled through further rectification process, and the CBS that distillation is separated out is refining dry through saltouing, and obtains the work in-process of CBS.

Claims (2)

1. one kind is improved the technique that DMF reclaims in the fluorescent brightener CBS production process, it is characterized in that may further comprise the steps:

,, the condensation body that reacts completely is tied up to be cooled to 0-20 ℃ in the reactor first after condensation reaction is finished as condensation system original solvents with DMF DMF, be incubated 1-2 hour, so that most of CBS in the condensation system is crystallized out;

Then enter whizzer the CBS that crystallization in the condensation system goes out is separated from reaction solvent, isolated centrifugal filter cake directly refining washing is dry, obtains the CBS work in-process;

The centrifugal organic filtrate that goes out is processed through simple distillation first, isolates the mixed fraction of reaction solvent DMF and methyl alcohol and the CBS that separates out;

Mixed fraction, with methyl alcohol and DMF separation and purification and is recycled through further rectification process, and the CBS that distillation is separated out is refining dry through saltouing, and obtains the work in-process of CBS.

2. the technique that DMF reclaims in the raising fluorescent brightener CBS production process according to claim 1 is characterized in that described whizzer is the sealing hanging bag type centrifugal machine, the quality of control centrifugal filter cake solid content 〉=80%.