Method and equipment for separating cyclohexanecarboxylic acid slurry

Abstract

The invention discloses a method and equipment for separating cyclohexanecarboxylic acid (CCA) slurry. The equipment mainly comprises a metal film penetrating separator; and a film pipe is arranged in the separator, and is provided with a stainless steel metal film with the aperture of 0.50 to 50 mu m. The method comprises the following steps of: introducing palladium-carbon catalyst-containing reaction mixed solution into an enclosed separator for separation through a buffer tank; and directly discharging the separated light phase into the next production procedure, concentrating the heavy phase in the separator, stopping feeding when the catalyst concentration reaches 10-30 weight percent, performing nitrogen stirring and clear liquid backwashing, and returning to a reactor. The separated light phase CCA product has the purity of 98-99 percent, and the catalyst content of zero. The separating process is automatically continuously carried out, power equipment is not required, the catalyst is not worn, the consumption of the catalyst is low, and the service life of the catalyst is long. The separating equipment is easy to operate, convenient to maintain, safe, environment-friendly and pollution-free.

Description

technical field [0001] The invention belongs to the technical field of chemical industry separation, and in particular relates to a method and equipment for separating cyclohexane carboxylic acid, a hydrogenation product of benzoic acid, and a Pd / C catalyst in the production process of caprolactam by using metal membrane separation technology. Background technique [0002] The hydrogenation of benzoic acid is an intermediate process in the production of caprolactam by the SNIA method. The reaction process uses benzoic acid and hydrogen as raw materials and uses Pd / C as a catalyst. The main product is cyclohexane carboxylic acid, and the by-products are CO and CO 2 , Cyclohexanecarboxylic acid (CCA for short) provides raw materials for the subsequent amidation process as an intermediate product. The production process of benzoic acid hydrogenation mainly includes reaction, catalyst separation, CCA distillation, gas treatment, etc. Among them, catalyst separation and CCA disti...

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Problems solved by technology

[0003] The catalyst separation and CCA distillation parts mainly have the following problems: (1) The content of palladium carbon catalyst in the CCA slurry is about 3%, and it is easy to wear and deposit during centrifugation, and the pipeline is blocked

(2) Since the carrier of the palladium-carbon catalyst is activated carbon, the mechanical strength is poor, and frequent collisions with the wall of the centrifuge by centrifugal force will cause the carrier to be broken and pulverized, resulting in the loss of the catalyst

(3) During the centrifugation of CCA slurry, the mechanical force will cause the separation of metal palladium and activated carbon carrier, which will reduce the catalyst activity.

(4) The light phase must be distilled to obtain high-purity CCA products, which requires increased equipment investment and operating costs. For a benzoic acid hydrogenation unit with an annual output of about 100,000 tons of CCA products, the centrifuge maintenance cost and distillation energy consumption are about 450 per year. around 10,000 yuan

[0004] A method for separating catalysts is disclosed in the invention patent with the authorized announcement number CN1224605C and the invention name "in the method of hydrogenation of benzoic acid". It is separated from the mixture and circulated back to the reactor, wherein the turbid liquid after hydrocyclone separation is circulated back to the reactor, the clear liquid enters the centrifugal separator, and after separation, the catalyst in the lower part is circulated back to the reactor, and the upper clear liquid is subjected to magnetic separation to separate out The catalyst of nickel-based auxiliary agent is circulated back to the reactor", this method can effectively separate nickel-based auxiliary agent and palladium-carbon catalyst, but it cannot solve the problems of the above-mentioned prior art

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