RU2714677C1 - Method of recovering activity of a zeolite-containing catalyst - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil refining industry, particularly, to recovery of activity of zeolite-containing catalysts of iso-dewaxing of diesel fractions. Invention relates to a method of reducing activity of a deactivated catalyst of a hydroprocessing process, characterized in that the catalyst used is a catalyst for oxidation of diesel fuel, which contains oxides of nickel, molybdenum, copper, boron and / or phosphorus and aluminum, which is subjected to regeneration, including drying catalyst in nitrogen flow at temperature of 200–210 °C for 3 hours, subsequent treatment of catalyst in nitrogen flow at 310–320 °C for at least 8 hours, further treatment of catalyst in nitrogen-air medium with concentration of oxygen 2 % vol. at stepped rise of temperature to 470 °C with holding for not less than 15 hours at each temperature in range of 380–390, 410–420, 465–470 °C, characterized in that after regeneration zeolite-containing catalyst is reactivated by impregnation with aqueous solution of diethylene glycol (DEG), wherein DEG is taken in an amount providing a molar ratio (Ni + Mo) / DEG equal to 1/1, or a mixture of DEG and citric acid (LC) is used, wherein DEG and LC are taken in an amount which provides a molar ratio (Ni + Mo) / (50–70 wt% DEG + 50–30 wt% LC) equal to 1/1, after which the catalyst is held in an impregnating solution, kneaded and dried at temperature of 110 °C for at least 10 hours, followed by treatment of the catalyst at temperature 350 °C for 4 hours in air.

EFFECT: design of a method of recovering activity of a deactivated zeolite-containing catalyst for diesel iso-dewaxing with activity and selectivity at a level corresponding to a similar fresh catalyst.

1 cl, 2 ex

Description

The method of restoring the activity of the catalyst relates to the refining industry, in particular to restoring the activity of zeolite-containing catalysts for isodeparaffinization of diesel fractions.

The oxidative removal of sulfur and coke from the surface of the spent catalyst leads to the restoration of activity to the level of 70-85%, the use of additional processing of oxidatively regenerated catalysts with chemical reagents can increase the degree of recovery of activity to 95% or more. To implement this stage, the catalyst is impregnated with aqueous or organic solutions of various organic or inorganic compounds, kept at a certain temperature, dried and sulfidized. The choice of a method for restoring catalyst activity depends not only on the achieved technical result, but also on the economic feasibility of its implementation at a specific site for the catalyst worked out under specific conditions.

As for zeolite-containing dewaxing / isodeparaffinization catalysts, the principles of their reactivation are similar to the reactivation of hydrotreating catalysts, since reactivation provides the restoration of the active metal phase present in the catalysts of both processes. Despite this, the reactivation of such catalysts requires additional control of the physicochemical characteristics, primarily due to the possibility of changing the structure of the zeolite, the main acid component of the catalyst during treatment with chelating agents.

A known method of regeneration of a deactivated catalyst for hydrotreating hydrocarbon feedstock comprising molybdenum, cobalt or nickel, sulfur and a carrier, by which the deactivated catalyst is calcined at a temperature of not more than 550 ° C in an air stream; then impregnated with a solution of citric acid in water, or at least one organic solvent, or in a mixture of water and organic solvents (alcohols with one or more hydroxyl groups or their methyl or ethyl esters are used as an organic solvent) and then dried in air at a temperature 50-220 ° C for 1-24 hours. Before impregnation, the calcined catalyst is evacuated to a residual pressure of not more than 50 Torr. The method allows to restore the activity of the catalysts by more than 99%. (RF patent No. 2484896, 04/09/2012).

The disadvantage of this method is that the data presented in the patent do not allow you to choose the optimal organic solvent for the preparation of an impregnating solution to restore activity. The estimation of the activity recovery for the catalysts according to the presented examples is from 99.6 to 100.6%, however, it is not indicated for which point of the experiment the calculation was carried out, is this the initial activity, is the activity maintained over time. Accordingly, it is not possible to conclude that the catalyst is stable.

Also known is a method of regenerating a hydrotreatment catalyst for diesel fuel comprising molybdenum, cobalt, sulfur and a carrier in which molybdenum and cobalt are contained in the catalyst in the form of a mixture of complex compounds Co (C ₆ H ₆ O ₇ ), H ₄ [Mo ₄ (C ₆ H ₅ O ₇ ) ₂ O ₁₁ ], H ₃ [Co (OH) ₆ Mo ₆ O ₁₈ ], sulfur is contained in the form of the sulfate anion SO ₄ ^2- . (RF patent No. 2622040, 08/22/2016).

The disadvantages of the method of regeneration of the catalyst in the patent of the Russian Federation No. 2622040 are similar to those indicated in the analysis of the patent of the Russian Federation No. 2484896, 04/09/2012.

Closest to the proposed technical solution is a method of regenerating a deactivated hydrotreating catalyst described in the patent of the Russian Federation No. 2674157, 08/07/2018. According to the described method, the deactivated catalyst is calcined at a temperature of not more than 650 ° C, then contacted with a reactive solution containing 0.55-2.7 mol / l of citric acid in an aqueous solution containing 10-20 mass. % butyldiglycol and 10-20 wt. % diethylene glycol. The catalyst discharged from the impregnator in a continuous stream is fed to a dryer. The result is a catalyst having a pore volume of 0.3-0.8 ml / g, a specific surface area of 150-280 m ² / g, an average pore diameter of 6-15 nm, containing, by weight. %: Co (C ₆ H ₆ O ₇ ) - 6.3-13.0; H ₄ [Mo ₄ (C ₆ H ₅ O ₇ ) ₂ O ₁₁ ] - 8.6-11.2; H ₃ [Co (OH) ₆ Mo ₆ O ₁₈ ] - 6.2-7.7; H ₆ [P ₂ Mo ₅ O ₂₃ ] - 4.0-10.2; SO ₄ ^2- - 0.7-2.6; PO ₄ ^3- - 0.5-4.4; the carrier is the rest. (RF patent 2674157, 08/07/2018).

The disadvantage of this method is the high calcination temperature of the deactivated catalyst, which can reach 650 ° C. At temperatures above 500 ° C, in addition to the removal of coke, partly the evaporation of molybdenum oxide, which is the active component of the catalyst, occurs. In addition, high regeneration temperatures lead to the formation of spinels and sintering of metal particles, which contributes to a decrease in catalyst activity. For calcination at this temperature under industrial conditions, additional energy is required.

A common disadvantage of the prototype and other patents presented is that they describe a method for restoring the activity of hydrotreating catalysts, respectively, their use for restoring the activity of catalysts of other hydroprocesses, in particular isodeparaffinization catalysts, and information on the effect of the operations on zeolites in the composition of isodeparaffinization catalysts are not shown .

The objective of the invention is to develop a method for restoring the activity of a deactivated zeolite-containing catalyst for the isodeparaffinization of diesel fuel by its oxidative regeneration or oxidative regeneration, followed by reactivation by impregnation with chelating agents, which makes it possible to obtain low-curing diesel fuel with activity and selectivity at a level corresponding to a similar fresh catalyst.

To solve this problem, a method is proposed for restoring the activity of a deactivated catalyst for a hydroprocessing process, which is characterized in that the catalyst is a catalyst for the process of isodeparaffinization of diesel fuel containing oxides of nickel, molybdenum, copper, boron and / or phosphorus and aluminum, which is subjected to regeneration, including drying catalyst in a stream of nitrogen at temperatures up to 200-210 ° C for 3 hours, subsequent processing of the catalyst in a stream of nitrogen at 310-320 ° C for at least 8 hours , Further treating the catalyst in a nitrogen-air atmosphere having an oxygen concentration of 2%. with a stepwise rise in temperature to 470 ° C with a holding time of at least 15 hours at each of the temperatures in the range 380-390, 410-420, 465-470 ° C.

If necessary, after regeneration, the zeolite-containing catalyst is reactivated by impregnation with an aqueous solution of diethylene glycol (DEG), whereby DEG is taken in an amount providing a molar ratio of (Ni + Mo) / DEG equal to 1/1, or a mixture of DEG and citric acid (LC) is used, moreover, DEG and LA are taken in an amount that provides a molar ratio (Ni + Mo) / (50-70% by mass. DEG + 50-30% by mass of LC) equal to 1/1, after which the catalyst is kept in an impregnating solution, dried and dried at a temperature of 110 ° C for at least 10 hours, followed by processing mended catalyst at 350 ° C for 4 hours in air.

Thus, a method of restoring the activity of a deactivated zeolite-containing catalyst for diesel isodeparaffinization involves the following steps:

- oxidative regeneration of a deactivated catalyst,

- reactivation of the regenerated catalyst, including the preparation of a solution of organic agents, impregnation and "maturation" of the regenerated catalyst;

- heat treatment of the reactivated catalyst.

1. Oxidative regeneration of a deactivated catalyst

It includes processing steps in a stream of nitrogen at a temperature not exceeding 320 ° C, and 3 processing steps in a nitrogen-air medium with an oxygen concentration of 2% vol. at a final temperature in the range of 450-500 ° C. In the range of 450-500 ° C there is a fairly complete removal of coke, as well as the restoration of the surface to 80% of the surface of the fresh catalyst. This temperature range is optimal for the regeneration of zeolite-containing catalysts.

2. Preparation of a solution of organic agents, impregnation and "maturation" of the regenerated catalyst

For reactivation, an aqueous solution of diethylene glycol (DEG) is prepared, which is taken in an amount providing a molar ratio of (Ni + Mo) / DEG equal to 1/1, or a mixture of DEG and citric acid (LC) in an amount providing a molar ratio of (Ni + Mo) / (50-70% wt. DEG + 50-30% wt. LC), equal to 1/1.

To do this, take a volume of water equal to 70% of the moisture capacity of the regenerated isodeparaffinization catalyst, which must be reactivated. The solution is stirred at a temperature of 70-80 ° C until the citric acid is completely dissolved and its volume is adjusted with distilled water to 100% of the moisture capacity of the regenerated catalyst.

The regenerated isodeparaffinization catalyst is dried and poured with a prepared solution of organic agents and mixed thoroughly without destroying the granules for 5 minutes. Leave the catalyst in a closed vessel, ensuring the absence of evaporation of water until the regenerated catalyst completely absorbs the solution of organic reagents.

3. Heat treatment of reactivated catalyst

The wet catalyst is dried in air at room temperature for 12 hours. Then subjected to drying in the mode of stepwise rise in temperature with exposure at a temperature of 110 ° C with possible subsequent calcination at a temperature of 350 ° C.

The proposed method for restoring the activity of nickel-molybdenum zeolite-containing isodeparaffinization catalyst allows to obtain a catalyst with a surface area of at least 210 square meters. m / g, mesopore volume of not less than 0.19 ml / g, preservation of the catalyst zeolite phase, content of strong acid sites determined by the method of thermoprogrammed ammonia desorption (TPD NH ₃ ), not more than 30%.

The degree of recovery of the activity of such a catalyst is up to 95% of the activity of a similar fresh catalyst with a forecast of stable operation over 2 years. The resulting catalyst provides catalyst selectivity in the target reactions of the conversion of long chain n-alkanes to produce winter or Arctic diesel fuel with a maximum filterability temperature of not higher than minus 38 ° C according to GOST 32511 or GOST R 55475. The method is implemented using inexpensive, commercially available reagents of domestic production on basis of simple technological stages.

The implementation of the proposed method is illustrated by examples.

Example 1

The activity recovery is subjected to a zeolite-containing nickel-molybdenum catalyst prepared by coextrusion according to RU patent No. 2662934, 07/31/2018, which was operated for 6 months in the process of isodeparaffinization of diesel fractions. The catalyst contains a mixture of high silica zeolites, hydrogenating metals - nickel and molybdenum, a boron trioxide promoter and a binder based on aluminum hydroxide.

The oxidative regeneration of the initial deactivated catalyst is carried out according to the following scheme: drying the catalyst in a stream of nitrogen at a temperature of up to 200-210 ° C for 3 hours; regeneration in a stream of nitrogen at 310-320 ° C for at least 8 hours, regeneration in a nitrogen-air medium with an oxygen concentration of 2% vol. with a stepwise rise in temperature to 470 ° C with an exposure of at least 15 hours at each of the temperatures in the range 380-390, 410-420, 465-470 ° C.

The resulting catalyst has a surface area of 211 square meters. m / g, which corresponds to 80% of the surface area of a similar fresh catalyst (263 m ² / g), the mesopore volume is 0.21 square meters. m / g, the proportion of strong acid sites in the NH ₃ TPD is 25%, which is slightly higher than in the fresh catalyst (by 9%), which allows maintaining the selectivity of the catalyst in the target reactions.

During the isodeparaffinization of a diesel fraction 180-350 ° С, having a cloud point of minus 5 ° С, pour point minus 14 ° С, at a pressure of 3.5 MPa, temperature 325 ° С an unstable hydrogenate with a pour point of minus 56 ° С was obtained, from which target diesel fuel with a yield of 90.8% by mass, with a flash point above 55 ° C, a maximum filterability temperature (PTF) of minus 38 ° C, which, according to other indicators, meets the requirements for winter class 3 diesel fuel according to GOST 32511-2013.

The estimated recovery value of the activity of the nickel-molybdenum zeolite-containing catalyst regenerated in accordance with the above example, determined on the basis of a comparison of the observed rate constants of the isodeparaffinization process with a forecast for 720 days of run, is 86.4% of the activity of the fresh catalyst. The regenerated catalyst can be operated at an isodeparaffinization unit with the addition of up to 10-15% of fresh catalyst, or on its own if the isodeparaffinization reactor is bypassed in the summer.

Example 2

The deactivated zeolite-containing nickel-molybdenum catalyst after the oxidative regeneration of Example 1 was reactivated. For this, a solution of citric acid (LC) and diethylene glycol (DEG) in water was prepared. The required volume of water is 70-80% of the moisture capacity of the regenerated catalyst, which must be reactivated. DEG and LC for the preparation of the mixture are taken in equal amounts. DEG + LC is taken in an amount that ensures their molar ratio to metals in the catalyst (Ni + Mo), equal to 1/1.

DEG, citric acid is added to the water, the solution is stirred at a temperature of 70-80 ° C until the citric acid is completely dissolved and its volume is adjusted with distilled water to 100% of the moisture capacity of the regenerated catalyst.

The regenerated isodeparaffinization catalyst is dried, if after regeneration it was not packaged in a sealed package, vacuum to a residual pressure of 5-10 mm Hg and pour the prepared solution of organic agents and mix thoroughly without destroying the granules for 5 minutes. Then the catalyst is periodically mixed in a closed vessel, ensuring the absence of water evaporation, without destroying the granules, in which they leave the solution of organic reagents to be absorbed by the regenerated catalyst for at least 10 hours.

The wet catalyst is dried in air at room temperature for 12 hours. Then subjected to drying in air in the mode of stepwise rise in temperature:

- rise to a temperature of 60 ° C (1 ° C / min), holding for 2 hours;

- rise to a temperature of 80 ° C (1 ° C / min), holding for 2 hours;

- rise to a temperature of 110 ° C (1 ° C / min), holding for 10 hours;

- rise to a temperature of 350 ° C (1 ° C / min), holding for 4 hours.

The resulting catalyst has a surface area of 245 square meters. m / g, which corresponds to 93% of the surface area of a similar fresh catalyst (263 m ² / g), the mesopore volume of 0.19 square meters. m / g, surface area having a pore diameter of 3.4-10 nm, (190 sq. m / g). Reactivated in accordance with the presented example, the isodeparaffinization catalyst contains medium strength acidic centers, similar to a fresh catalyst, the proportion of strong acidic centers according to the NH ₃ TPD is 27%, which is slightly higher than in a fresh catalyst (by 11%), which allows the catalyst selectivity to be maintained in targeted reactions. By the method of X-ray phase analysis, the presence of a phase related to the zeolite was established, which indicates that the zeolites were not destroyed during the reactivation by organic agents.

During the isodeparaffinization of a diesel fraction 180-350 ° С, having a cloud point of minus 5 ° С, pour point minus 14 ° С, at a pressure of 3.5 MPa, temperature 325 ° С, an unstable hydrogenate with a pour point of minus 53 ° С was obtained, from which target diesel fuel with a yield of 92.1% by mass, with a flash point above 55 ° C, a maximum filterability temperature (PTF) of minus 38 ° C, which, according to other indicators, meets the requirements for winter class 3 diesel fuel according to GOST 32511-2013. Arctic diesel fuel with PTF below minus 44 ° C was obtained at a process temperature of 335 ° C. The yield of the target diesel fuel on the reactivated catalyst is higher than on the regenerated one according to Example 1 (90.8% wt.), Close to the yield on the fresh catalyst (92.9% wt.).

The estimated recovery value of the activity of the nickel-molybdenum zeolite-containing catalyst reactivated in accordance with the given example, determined on the basis of a comparison of the observed rate constants of the isodeparaffinization process with a forecast for 720 days of run, is 94.6% of the activity of the fresh catalyst. The activity of the catalyst is restored almost completely, the reactivation method is implemented on the basis of simple technological stages using inexpensive, commercially available reagents of domestic production.

Claims (2)

1. A method of restoring the activity of a deactivated catalyst for a hydroprocessing process, characterized in that the catalyst is a catalyst for the process of isodeparaffinization of diesel fuel containing oxides of nickel, molybdenum, copper, boron and / or phosphorus and aluminum, which is subjected to regeneration, including drying the catalyst in a stream of nitrogen at temperatures up to 200-210 ° C for 3 hours, subsequent processing of the catalyst in a stream of nitrogen at 310-320 ° C for at least 8 hours, further processing of the catalyst in nitrogen-air hydrochloric environment with an oxygen concentration of 2%. with a stepwise rise in temperature to 470 ° C with a holding time of at least 15 hours at each of the temperatures in the range 380-390, 410-420, 465-470 ° C. 2. The method according to p. 1, characterized in that after regeneration, the zeolite-containing catalyst is reactivated by impregnation with an aqueous solution of diethylene glycol (DEG), whereby DEG is taken in an amount providing a molar ratio (Ni + Mo) / DEG equal to 1/1, or use a mixture of DEG and citric acid (LK), wherein DEG and LK are taken in an amount that provides a molar ratio (Ni + Mo) / (50-70% by mass of DEG + 50-30% by mass of LK) equal to 1/1, after whereupon the catalyst is kept in an impregnating solution, dried and dried at a temperature of 110 ° C for at least 10 hours, from the last blowing catalyst by treating at 350 ° C for 4 hours in air.