JPS58104685A - Method for separating and recovering waste liquid used for preparation of phenol resin - Google Patents

Abstract

PURPOSE:To recover methanol and phenol at a low cost, by separating and recovering methanol of purity above 95% at the initial stage of distillation, and shifting phasic equlibrium by lowering the concentration of methanol and cooling methanol. CONSTITUTION:A column 2 packed with cotton, glass wool or the like is connected to a reacting caldron 1, and a condenser 3 and a circulating pipe 11 are connected to the packed column 2. To a change-over valve 5, a methanol recovering vessel 6 and a phenol recovering vessel 7 are connected by a branched pipe. A cooler 8 is provided between the change-over valve 5 and the phenol recovering vessel 7, and a coolant is circulated through the cooler 8. The condensation product of phenol resin and condensed water formed in the preparation of phenol resin are accumulated in the reacting caldron 1, and the condensed water is treated as a waste liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for separating and recovering phenol and methanol from a waste liquid generated during the production of phenolic resin. A method for producing phenolic resin manufacturing waste liquid, which is characterized by separating the lower phase liquid from the M armpit by cooling a ζO distillation vessel to lower the liquid temperature, and then separating the liquid from the lower phase of the M armpit. This relates to separation and recovery methods.

In producing phenolic resin, waste liquid is generated by dehydrating phenolic resin wire hardware. This waste liquid contains 6% by weight of unreacted free phenol, about 4% by weight of methanol, and about 1% by weight of formalin, and the residue is poured with water. Conventionally, this waste liquid has generally been disposed of by oxidation methods, combustion methods, activated sludge methods, etc., which have been very rare. However, in recent years, it has been desired to reuse waste liquids due to issues such as resource conservation and distribution, and various methods for recovering phenol and methanol from waste liquids have been studied. One method is to extract the diphenol from the waste liquid with ether, phase separate it, and then purify it by distillation, but this method involves a large loss of ether and is disadvantageous in terms of cost, as well as being complicated and requiring large equipment. There is a problem with becoming stale. 1
+ Also consider a method of adsorbing phenol onto it using an ion exchange resin, desorbing it with methanol, and distilling it.''l)h In this method, the cost of the ion exchange resin is high, making it disadvantageous in terms of cost, and the accuracy of adsorption and separation is low. There is a problem that the separation and recovery rate is low.Furthermore, a method is being considered in which the waste liquid is adjusted to acidic and formalin is added to convert the waste liquid phenol into a resin and then recovered, but this method has a low reaction rate. It is rarely practical because the reaction time is low and the viscosity of the resulting resin is high and it is difficult to discharge it from the straw.

The present invention has been made in view of the above points, and is a separation and recovery method for phenol resin manufacturing waste liquid that can efficiently recover phenol and methanol, is simple to operate, and is inexpensive. The purpose is to provide the following information.

The present invention will be explained in detail below with reference to Examples. A packed tower (2) filled with cotton, glass wool, etc. is connected to the reaction island (1), and a condenser (3) and a reflux pipe (+r) are connected to this packed tower (2). (4) is the reflux ratio adjustment valve, (6) is the switching valve,
A methanol recovery container (6) is connected to the switching valve (6) by a branch pipe.
) and the refrigerant is passed through the cooler (8). - Therefore, the phenolic resin condensate and condensed water produced during the production of phenolic resin are stored in the reaction ≦ (1), and this condensed water is treated as waste liquid, and from this waste liquid In order to separate and recover phenol and methanol, after the -combination reaction is completed, the reaction vessel +1
The packed column (2) is heated under reduced pressure (or by using the residual heat from the condensation reaction) to operate the R flow ratio adjusting pulp (4).
, a condenser (3), and a reflux tube (+1) to first separate methanol while refluxing it in a cycle and collect it in a methanol recovery container (6). At the beginning of the distillation, methanol is mainly recovered, but then methanol, phenol, and water are distilled individually in an azeotropic mixture with methanol reduced and sent to the phenol recovery vessel (7).

Here, as shown in the mutual solubility curve in the water-phenol-methanol system in Figure 2, when the amount of methanol is 4.7% as shown at point a in Figure 2, the island in the phenol recovery container (7) The phenol concentration of the lower phase (9) of the molasses is 7.91, but the concentration of phenol in the lower phase (9) in Figure 2 is 7.91. .

As shown in point b, when the methanol concentration is reduced to 1.6% by weight, the phenol concentration in the lower phase (9) is 66.7% by weight, and there is a clear tendency that phenol llf increases as the methanol concentration decreases. It appears in In addition, as seen in the phenol-water mutual solubility curve in Figure 3, when the solution temperature is 50°C as at points a and a' in Figure 3, the upper phase of Am& in the phenol recovery container (7) - The phenol concentration in the lower phase (9) is 12% by weight, and the phenol concentration in the lower phase (9) is 6%.
However, when the solution temperature was lowered to 20°C, the upper phase (phenol II of 101) f became 8.12% by weight and 1% by weight.
The phenol concentration of phase (9) is 71.8 g,
There is a clear tendency that when the solution temperature is lowered, the phenol concentration in the upper phase tto+ decreases and the phenol af in the lower phase (9) increases. Therefore, if the liquid is cooled to ## in the phenol recovery container (7) with the methanol concentration lowered, the phenol IIk & of the lower phase (9) of the vapor in the phenol recovery container (7) will be increased. will be possible.

Most of the methanol is already recovered in the methanol recovery container (6) at the initial stage of distillation, and the concentration of methanol in the koji liquid recovered in the phenol recovery container (6) is small. Thereupon, the phenol recovered in the phenol recovery tank (6) is further cooled down by a cooler (8). It is preferable to cool the steam tank liquid to 5 to 20 tons.

As described above, pure methanol (more than 95%) is first separated and recovered in the initial stage of distillation, and then the concentration is reduced to about 65-75@IL% by lowering the methanol concentration and shifting the phase equilibrium by cooling. Highly concentrated phenol is recovered by removing the lower phase of the shimakoji paste in the phenol recovery container. According to the invention, therefore:
There is no need to use additives or ion exchange resins, and simply by adding cooling operations and equipment, high concentrations of methanol and phenol can be recovered at low cost with the same simple operations and equipment as normal distillation operations. It is possible. The recovered methanol and phenol are reused.

[Brief explanation of the drawing]

Figure 1 is a peak diagram of the apparatus used in the present invention, Figure 2 is a graph showing the mutual solubility of the water-phenol-methanol system (at 25°C), and Figure 3 is a graph showing the mutual solubility of the phenol-water system. . (1) is a straw straw, (3) is a condenser, (6) is a methanol recovery container, (7) is a phenol container, and f81 is a cooler. Agent Patent Attorney Ishi 1) Chief 7 Figure 1 Figure 2, E-phase Lower J
li (wt%) Figure 3

Claims (1)

[Claims] (1) Methanol is first distilled and separated from the waste liquid containing free phenol, methanol, and water, and then the remaining amount is distilled and the sagging vapor is cooled to lower the liquid temperature. A method for separating and recovering phenolic resin manufacturing waste liquid, which is characterized by separating the liquid.