RO108679B1 - Process for therm catalytic decomposition of phenolic residues - Google Patents

Abstract

The invention relates to decomposition phenolic residues, to a conversion thereof of 88-96%, in recoverable liquid products, using a YH + aluminosilicate synthetic catalyst ultrasound immersed in liquid at temperatures 2,000 ... 300 ° C and residual pressure of 50 ... 100 mm Hg, which ensures a superior capitalization of a them.

Description

The present invention relates to a process for the thermocatalytic decomposition of phenolic residues, which, in general, are used as fuel, in order to recover useful products, which can be recirculated in the process of phenol manufacture by the cumene process.

The processes known so far refer to the recovery of phenolic residues by: fractional distillation, thermal cracking, catalytic hydrogenation or catalytic decomposition (RO 89865; 99518).

These processes present as disadvantages an exaggerated corrosion, low conversions and selectivity, the need for regeneration after a small number of uses of the catalyst or obtaining large quantities of wastewater.

Also known is the decomposition of phenolic residues using an aluminosilicate containing catalyst

10 .. .13% silimanite, 5 ... 8% zeolite NaY and aluminosilicate. The decomposition process starts at 250 ... 400 ° C and is carried out in the presence of steam, passing the residue over a fixed layer of catalyst. This solution presents as disadvantages the obtaining of large quantities of phenolic water, with implications in their subsequent purification, as well as small conversions and selectivities (US 583996).

The process according to the invention removes the disadvantages shown by using an ultrastable YH ⁺ aluminosilicate of chemical composition in moles 4.6 ... 5.3 SiO ₂ x A1 ₂ O ₃ x 0.004 Na ^ x 6H ₂ O, at temperature 200 ... 300 ° C and remaining pressure of

50 .. .100 mmHg, at a volumetric ratio of catalyst: 5: 1 phenolic residue, the catalyst being immersed in the liquid.

The process according to the invention has the following advantages:

- exaggerated corrosion (acid catalysis) is eliminated;

- increased conversions and selectivity (88 ... 96%);

- elimination of the phenolic waters resulting from the process, to which is added the simplicity of the adopted technology.

The following is an example of carrying out the process, in relation to FIGS. 2 and 2, which represents:

-fig.l, the diagram of a laboratory installation for the thermocatalytic decomposition of phenolic residues;

- fig.2, the diagram of an industrial installation on which the decomposition of these residues can be realized.

The laboratory installation is composed of a distillation plate 1 of V ₂ A, filled with catalyst, which has; a thermometer for measuring the temperature in the distillation a, feed mouth b, a thermometer for measuring the temperature of the vapor c and the socket d for measuring the pressure in the system, a descending refrigerant 2, a collecting flask 3, a vacuum pump 4, an electric motor 5 and a gas bulb 6.

The industrial plant where such a decomposition can be carried out is composed of a distillation plate 7 of V ₂ A, filled with YH ⁺ catalyst, centrifugal pumps 8 and 9, a water-cooled condenser 10, a soil-cooled condenser 11, a distilled collection vessel 12, a vacuum pump 13, a solver 14, a cyclone 15 and a blower 16.

Decomposition of phenolic residues containing α-methylstyrene 1 ... 2%, phenol

2 .. .5%, dimethylphenylcarbinol 8-12%, acetophenone 20-30%, alphamethylstyrene dimer 22-35%, p-cumyl phenol 10-22%, heavy products

15 .. .20% aluminosilicate is carried out in the presence of YH ⁺ of a particular composition, explained below, at temperatures

200 .. .300 ° C and pressures 50 ... 100 mmHg with a conversion into useful products of 88 ... 96%.

The aluminosilicate used has the following properties:

- appearance: cylindrical granules of white color;

- dimensions: diameter 2 ... 3 mm length 5 ... 8 mm;

- chemical composition in moles: 4.6 ... 5.3 SiO ₂ x A1 ₂ O ₃ x 0.004 Na ₂ O x 6H ₂ O;

- absorption capacity for benzene, g / 100 g catalyst, minimum 16;

- mechanical compressive strength, kgf / mm ² , minimum 1,2;

- thermal stability, minimum 850 ° C;

- Na content,% gr., maximum

0.635;

- cumene cracking index, IO ' ⁷ mx mole / sec. g, minimum 1000;

- conversion,%, minimum 100;

- selectivity, minimum 94%.

In a 1.5 l vessel without stirring, constructed of stainless steel, catalyst was inserted until filling and 300 ml of phenolic residue.

During the experiments, the temperature of the distilled vapors was measured and 5 were left over from the laboratory installation.

A total of 35 experiments were performed. Prior to the first catalyst regeneration test, examples of compositions are given in 5 of the experiments (Table L).

Table 1 :

Chromatographic analysis of the fractions obtained at the decomposition of phenolic residues

Nr. crt. FRACTION ANALYSIS,% Pear- end Ace- ton dia- ketone One cool Oxide of mezi- iso pro- pil- necessarily the zen butyl necessarily the zen Alpha- methyl styrene Ace- tofe- canrenone Phenol a resident, duu 1 0.80 0.10 0.40 0.20 4.10 0.60 39,00 18,20 36.6 lack 2 0.30 1.00 1.20 1.80 8.00 - 35.10 20.20 32.4 lack 3 0.40 2.70 1.90 2.20 10.70 - 26.00 19,20 36.9 lack 4 0.24 2.39 1.20 1.35 9.85 - 33:11 17.97 33.89 lack 5 0.22 1.96 1.13 1.10 9.94 - 29.59 23.89 33.17 lack

In order to obtain a maximum conversion of the phenolic residues, several working variants were tried, with the aim of establishing the optimum working conditions, as well as the installation able to achieve this.

The optimal solution to achieve this goal is to work with catalyst immersed in liquid, at volumetric ratios of catalyst / phenolic residue of 5/1 with temperatures up to 300 ° C and pressures of

50 ... 100 mmHg. The reaction time is reduced by half, compared to the reaction time achieved under working conditions at atmospheric pressure.

What is extremely important is that there are no untransformed residues, the difference between the quantity introduced and the resulting liquid quantity constituting the gases in the form of paraffins and non-condensable olefins going up to C ₅ , products resulting from the cracking processes.

The catalyst used had a ratio of SiO ₂ / Al ₂ O ₃ = 3; SiO ₂ / Na ₂ O = 5; SiO ₂ / 5H ₂ O = 3; Al ₂ O ₃ / Na ₂ O = 1.64;

A1 ₂ O ₃ / 5H ₂ O = 1.13 and Na ₂ O / 5H ₂ O = 0.68.

The phenolic residues are fed into the distillation pad 7 filled with YH ⁺ catalyst, with pump 8.

The ratio between the catalyst introduced and the residue is 5: 1. The temperature in the hearth of the distillation plate is ensured by combustion of the methane gas or other energy source capable of reaching a temperature of up to 300 ° C inside the reactor. The reactor is subjected to vacuum by the vacuum pump 13, which produces in the reactor 50-100 mmHg remaining pressure. The vapors resulting from the decomposition are condensed in capacitors 10 and 11, the first cooled by water, the second with soil, and the distillate collected in the vessel 12 is sent with the centrifugal pump 9 in the manufacturing flow, in order to separate the components. In order to recover non-condensable gases after condenser 11 (paraffins, olefins), they can be sent to a container and then to a compressor, in order to separate the components or use them as combustible gas. In the event that, for one reason or another, residues that remain in the blast remain untransformed, they can be trapped on a solver for use as solid fuel.

Experiments in laboratory conditions have shown that the results are similar or very close to a number of 35 decomposition operations without any intervention.

If the conversion falls below 65% and the residue is transformed, the regeneration of the catalyst is required by the introduction of steam for the desorption of hydrocarbons from the pores of the catalyst and then the introduction of air at 400 ... 450 ° C, in order to burn the deposited coke. The temperature regulation in the catalytic layer is made by introducing steam under conditions in which the temperature exceeds 500 ° C. Although it is known that this catalyst is ultrastable and resistant to temperatures above 850 ° C, temperatures above 500 ° C are not recommended for regeneration.

Under the conditions in which the catalyst is used, the discharge is made after the desorption of steam gases, by pneumatic transport, using cyclone 15 and blower 16.

Claims (1)

Claim Process for thermocatalytic decomposition of phenolic residues, characterized in that it uses an ultrastable YH ⁺ aluminosilicate, of chemical composition in moles 4.6 ... 5.3 SiO ₂ x A1 ₂ O ₃ x 0.004 NajO x 6H ₂ O, at temperature at 200 ... 300 ° C and a remaining pressure of 50 ... 100 mmHg, at a volumetric ratio of catalyst: 5: 1 phenolic residue, the catalyst being immersed in the liquid.