JPS61151140A - Hydrochloric acid recovery method from waste gas in the production of bisphenol - Google Patents

Abstract

PURPOSE:In the production of the titled compound from a phenol and a carbonyl compound using hydrogen chloride as a catalyst, the waste gas from the reactor is washed with the phenol and treated with water or diluted hydrochloric acid to enable recovery of hydrochloric acid. CONSTITUTION:When a bisphenol is produced from a phenol 1 and a carbonyl compound 2 using hydrogen chloride as a catalyst, the waste gas from the reactor 4 is washed with the phenol to remove the carbonyl compounds in the waste gas, then the hydrogen chloride included in the washed waste gas is preferably absorbed in wager or dilute hydrochloric acid of 0-25% hydrogen chloride concentration 9, and recovered as hydrochloric acid 11. The process according to the present invention enables the recovery of hydrochloric acid, avoiding the clogging in the hydrochloric acid recovery system caused by formation of bisphenol. Further, the disposition of waste water of strong acidity containing high concentration of organic substance becomes unnecessary, resulting in reduction of costs.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for recovering hydrochloric acid from waste gas discharged from a reaction apparatus during the production of bisphenol compounds from phenols and carbonyl compounds using hydrogen chloride as a catalyst.

[Conventional technology]

Bisphenol compounds are industrially produced from phenols and carbonyl compounds using hydrogen chloride as a catalyst in a batch reactor. The gas phase of this reactor is hydrogen chloride, which must be kept at a high concentration of usually 95% or more in order to shorten the reaction time and suppress the production of by-products.

On the other hand, as the reaction progresses, condensed water is generated and absorbs hydrochloric acid gas, resulting in a shortage of hydrogen chloride in the gas phase. For this reason, hydrogen chloride is replenished, but impurity gases that are not absorbable to water, such as nitrogen and oxygen, accumulate in the gas phase, resulting in a decrease in the hydrogen chloride concentration, resulting in an insufficient concentration.

For this reason, a waste gas cleaning tower was installed to exhaust the gas in the reactor by absorbing hydrochloric acid gas into the cleaning water, and then replenishing with fresh hydrogen chloride to maintain the required purity.

However, in this method, not only hydrogen chloride is lost, but also a large amount of acidic wastewater containing phenols and carbonyl compounds is generated which is exhausted together with the exhaust gas, and the treatment of this wastewater requires a large amount of cost.

On the other hand, as a method for recovering hydrogen chloride, it is absorbed into low-concentration cold hydrochloric acid to increase its concentration, evaporated in a distillation column to obtain hydrogen chloride, and the low-concentration hydrochloric acid, which is the bottoms, is cooled and reused as an absorption liquid. The method used is common.

However, since bisphenol compound manufacturing waste gas contains phenols and carbonyl compounds, it accumulates in the hydrogen chloride recovery system and becomes bisphenol compounds that clog the system and make it virtually inoperable6. In reality, the hydrogen chloride exhausted from this reactor cannot be recovered, resulting in a loss of hydrogen chloride and highly acidic wastewater containing high organic matter, which requires a large amount of processing cost.

[Problem that the invention seeks to solve]

The present invention has been made based on the above-mentioned viewpoint, and an object of the present invention is to provide a good method for recovering hydrochloric acid from waste gas discharged from a reaction device when producing the above-mentioned bisphenol compound.

[Means for Solving the Problems] In order to achieve the above object, the present inventors conducted extensive studies and finally arrived at the present invention.

That is, in the present invention, when producing bisphenol compounds from phenols and carbonyl compounds using hydrogen chloride as a catalyst, the gas discharged from the reaction device is washed with phenols, and then the hydrogen chloride contained in the gas is absorbed into water or dilute hydrochloric acid. This is a method for recovering hydrochloric acid from bisphenol compound production waste gas.

According to the method of the present invention, carbonyl compounds in the gas can be removed by washing the gas discharged from the reactor with phenols, thereby avoiding blockages due to the production of bisphenol compounds in the hydrochloric acid recovery system and making it possible to recover hydrochloric acid. Become. Moreover, when phenols are used in the absorption liquid, not only is the absorption performance good, but also the liquid that has absorbed the carbonyl compound can be used as it is as a raw material for bisphenol compounds. In this case, the most efficient method is to use a portion of the phenol solution as the raw material for the bisphenol compound as an absorption solution.

The amount or concentration of water or dilute hydrochloric acid used to recover hydrogen chloride from cleaned waste gas is determined depending on the gas amount and absorption temperature, but the ease of generation during absorption and recovery is 0. A concentration of about 25% is desirable. The amount used varies depending on the concentration of dilute hydrochloric acid, etc., but it is usually preferably 1 to 50 kg/H per 1 kg/H of hydrochloric acid gas in the waste gas.

Hereinafter, one embodiment of the method of the present invention will be explained with reference to the drawings.

Figure 1 shows that bisphenol A is produced by introducing hydrogen chloride as a catalyst from phenol and acetone according to the method of the present invention.
FIG. 2 is a process flow chart showing one embodiment of a method for recovering hydrogen chloride as hydrochloric acid from waste gas discharged from a reaction device when producing .

1 phenol, 2 acetone, and 3 hydrogen chloride catalysts are charged into a reactor 4 to synthesize bisphenol. The waste gas 5 discharged from the reactor 4 is introduced into a phenol cleaning tower 6. The waste gas 5 is washed in the phenol cleaning tower 6 with phenol 7 taken out from the charged phenol 1 to remove acetone, and the waste gas 8 containing hydrogen chloride is sent to the hydrochloric acid absorption tower 9 to cool the hydrogen chloride. Cold hydrochloric acid 11, which has been absorbed into dilute hydrochloric acid 10 and has an increased concentration, is recovered. The phenol 12 that has absorbed acetone etc. is charged into the reactor 4 by a pump 13. Incidentally, the impurities 14 in the waste gas are washed with water by a conventional method and then released into the atmosphere.

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 In FIG. 1, the flow rate of the waste gas 5 discharged from the reactor 4 of the bisphenol A production facility was 18.08 kg/H, and its component flow rates were as follows.

Hydrogen chloride 16.05 kg/H phenol
0.06 kg/H Acetone 116 kg/H Water o4a kg/H Non-condensable gas 0.57 kg/H (total) 18.08 kg/H This waste gas is led to the phenol cleaning tower 6, and part of it is removed from the charged phenol 1. After washing with 400 kg/h of phenol 7,
The composition of the phenol cleaning bath gas 8 was as follows, and acetone was almost completely removed.

Hydrogen chloride 13.22 kg/H phenol
0.11 kg/ H acetone Trace water Trace non-condensable gas 0.57 kg/ II (total)
13.90 kg/II This phenol cleaning bath gas 8 is led to a hydrochloric acid absorption tower 9, and is heated to 200 kg/II at 15°C.
It was absorbed in 10% of 20% hydrochloric acid.

The composition of gas 14 discharged from the hydrochloric acid absorption column was as follows.

Hydrogen chloride 0.05 kg/H phenol
Trace acetone Trace water 0.19 kg/tl Non-condensable gas 0.57 kg/H (total) 0.81 k
g/H Therefore, according to the present invention, hydrogen chloride is reduced to 16.0 g/H in the waste gas.
0.05k in the gas from the hydrochloric acid absorption tower out of 5 kg/H
Excluding g/u, 16.00 kg/H was recovered, which means that 99.7% of the hydrogen chloride that was previously lost was recovered. Additionally, the hydrogen chloride content, which conventionally required wastewater treatment, was reduced to 16.00 kg/l and phenol to 0.0 kg/l.
6kg/h, acetone 1, 16kg/h no longer requires wastewater treatment, reducing costs.

Example 2 The flow rate of waste gas discharged from the reactor of the same bisphenol A production facility as in Example 1 was 45.89 kg/H, and the component flow rates were as follows.

Hydrogen chloride 40.71 kg/H phenol
0.30kg/H Acetone 2.94kg/L (Water
0.58 kg/H non-condensable gas 1
．． 36 kg/II (total) 45゜89 kg/H This waste gas was led to the phenol cleaning tower and washed with 1000 kg/■ of phenol, which was partially extracted from the charged phenol, and the gas composition coming out of the phenol cleaning bath was as follows. ,
Acetone was almost completely removed.

Hydrogen chloride 33.63 kg/ If phenol 0.35 kg/H acetone Trace water Trace non-condensable gas 1.36 kg/l ((total)
35.34 kg/H This phenol washing bath gas is led to a hydrochloric acid absorption tower, and is heated to 500 kg of added % hydrochloric acid at 15°C.
g/II.

The composition of the gas discharged from the hydrochloric acid absorption tower was as follows.

Hydrogen chloride 0.11 kg/H phenol
Trace acetone Trace water 0.47 kg/Ii Non-condensable gas 1.36 kg/H (total) 1.94 kg/II Therefore, the present invention recovers 40.60 kg/II of hydrogen chloride, which was previously lost. This means that 99.7% of the hydrogen chloride was recovered. Additionally, as a result, hydrogen chloride (40.60 kg/II), phenol (0.30 kg/H), and acetone (2.94 kg/H), which conventionally required wastewater treatment, no longer requires wastewater treatment, resulting in cost savings. .

〔Effect of the invention〕

Since the present invention has the above-described configuration, when producing bisphenol compounds, it is possible to recover hydrochloric acid from waste gas that was conventionally disposed of, and accordingly, it is possible to treat strongly acidic wastewater containing high organic matter, which was previously required. You can save costs.

[Brief explanation of the drawing]

FIG. 1 is a process flow chart showing an example of the hydrochloric acid recovery method according to the present invention.

Claims (1)

[Claims] When producing bisphenol compounds from phenols and carbonyl compounds using hydrogen chloride as a catalyst, the gas discharged from the reaction device is washed with phenols, and then the hydrogen chloride contained in the gas is absorbed into water or dilute hydrochloric acid. A method for recovering hydrochloric acid from bisphenol compound manufacturing waste gas.