RU2096085C1 - Method of restoring activity of platinum-containing reforming catalyst - Google Patents

Abstract

FIELD: catalyst regeneration. SUBSTANCE: full restoration of catalytic activity is achieved when treatment with hydrogen- containing gas following treatment with organochlorine compound is performed by way of periodically (not less than twice) raising pressure from 0.5-0.7 to 2.2-2.5 MPa, aging for 5-6 h, and consequently lowering pressure to 0.5-0.7 MPa. EFFECT: improved catalyst regeneration efficiency.

Description

 The invention relates to methods for restoring the activity of platinum-containing reforming catalysts and can be used in the refining and petrochemical industries.

 During operation, coke is deposited on the surface of alumina-platinum reforming catalysts and there is a need for their regeneration, which consists of the stages of coke burning, calcination in an oxidizing medium and reduction with a hydrogen-containing gas (VGS).

 When processing gasoline fractions containing more than 1 ppm sulfur at reformers, it accumulates on the surface of alumina-platinum catalysts. Excess sulfur interferes with the efficient regeneration of the catalysts.

A known method of restoring the activity of platinum-containing catalysts poisoned with sulfur [1] by its oxidation at a temperature above 454 ^o C and an oxygen concentration of not more than 0.1 mol. followed by oxidative burning of coke at a lower temperature and higher oxygen concentration.

 The disadvantage of this method is the formation in the presence of a catalyst and oxygen sulfur trioxide, irreversibly deactivating the catalyst.

A known method of reactivation of reforming catalysts poisoned with sulfur [2] by treating the catalyst with hydrogen-containing gases (WASH) with a hydrogen sulfide content of less than 2 mg / m ³ for 2-100 hours at a temperature of 480-530 ^o C, burning coke at 400-520 ^o C , a pressure of 0.1-4.0 MPa, the content in the circulating VSG 1-10 mol. oxygen and 1-10 m ³ water per 1000 m ³ gas, adding chlorine, for example dichloroethane or trichlorethylene, in an amount of 0.05-1.2% by weight of the catalyst, calcining in air at a temperature of 480-530 ^o C and 0.1 4.0 MPa. VSG is used with a hydrogen sulfide content of less than 2 mg / m ³ .

 Removal of sulfur compounds occurs not due to oxidation, but due to their reduction to hydrogen sulphide in the medium of the WASH.

 The disadvantage of this method is the small sulfur content in the deactivated catalyst (not more than 0.2% wt.), In which it is possible to restore its activity.

The closest to the invention in technical essence and the achieved effect is a method of reactivation of a platinum-containing catalyst for reforming gasoline fractions [3 prototype] according to which sulfur-poisoned catalyst is initially treated with HSG at 480-530 ^o C, then oxidative regeneration is carried out at 400-520 ^o C, after which the coke-free catalyst is subjected to VHS with a hydrogen sulfide concentration of less than 2 mg / m ³ at 500-520 ^o C, again create an oxygen-containing medium and at 480-530 ^o C, the oxygen content of 5-10 mol. treat the catalyst with an organochlorine compound in an amount of 0.5-1.2% of chlorine based on the weight of the catalyst, then restore it with dry HSG at 350-500 ^o C.

 The disadvantage of the method adopted for the prototype is the insufficiently complete restoration of the activity of the catalyst.

 The aim of the invention is the complete restoration of the activity of sulfur-deactivated reforming catalysts.

 This goal is achieved by a method of restoring the activity of a platinum-containing reforming catalyst poisoned with sulfur, according to which the treatment with a hydrogen-containing gas after treatment with an organochlorine compound is carried out by periodically, at least 2 times, increasing the pressure from 0.5 to 2.5 MPa, holding for 5-6 hours followed by a decrease in pressure to 0.5-0.7 MPa.

 Conducting desulfation of poisoned platinum-containing catalysts by the proposed method allows you to fully restore its activity.

 An essential distinguishing feature of the proposed method compared to the method adopted for the prototype is the hydrogen activation of the catalyst by periodically, at least two times, increasing the pressure of the WAG from 0.5-0.7 to 2.2-2.5 MPa and its subsequent reduction.

With a decrease in pressure, the sulfur-containing VSG is blown out of the system, and with a subsequent increase, the system is filled with fresh VSG with an H ₂ S concentration of less than 2 mg / m ³ .

 Thus, the claimed method meets the criterion of "novelty."

The method is as follows. The platinum-containing reforming catalyst deactivated under industrial conditions is reduced. After stopping the supply of raw materials, it is subjected to the processing of WASH at a temperature of 480-530 ^o C, then in order to burn coke, oxidative regeneration is carried out in a stream of nitrogen containing 1-3 vol. oxygen, when the temperature rises from 250 to 520 ^o C, the catalyst is further processed in the VGS medium with a hydrogen sulfide concentration of less than 2 mg / m ³ at a temperature of 480-530 ^o C and a pressure of 2.0-2.2 MPa for 24-48 hours . In this case, partial removal of sulfur from the catalyst in the form of hydrogen sulfide occurs.

The recovered catalyst is subjected to oxychlorination treatment with dichloroethane supplied in an amount of 0.5-0.8% chlorine by weight of the catalyst in a stream of nitrogen containing 3-5 vol. oxygen. Oxychlorination is carried out at a temperature of 480-520 ^o C for 2 hours, followed by exposure for 6 hours at a temperature of 500-510 ^o C without feeding dichloroethane, then create a reducing environment and carry out hydrogen activation of the catalyst at a temperature of 480-530 ^o C and pressure 0.5-0.7 MPa for 2-3 hours.

Further, the pressure is increased to 2.2-2.5 MPa and the system is kept at this pressure for 5-6 hours, followed by a decrease in pressure to 0.5-0.7 MPa with simultaneous blowing off of sulfur-containing VSG and filling of the reactor system with fresh VSG containing no more than 2 mg / m ^{3 of} hydrogen sulfide. The increase in pressure and the discharge of the WASH is carried out at least 2 times.

The reforming of the gasoline fraction 85-180 ^o C is carried out in the presence of an AP-56 plating catalyst, reactivated according to the above method, at a temperature of 495 ^o C, a pressure of 3.0 MPa, a feed volumetric feed rate of 1.5 h ^-1 and a VSH circulation rate of 1200 nm ³ / m ³ raw materials. Under these conditions, a stable catalyst is obtained with an octane rating of more than 77 points (m.m.) and a yield of 87.5 wt.

 The positive effect when using the proposed method is associated with operations following oxychlorination, which possibly contribute to the exhaustive removal of sulfate sulfur from the catalyst. In addition, oxychlorination of the catalyst before reduction, apparently, contributes to the activation of platinum.

 Analysis of the known technical solutions for the reactivation of platinum-containing reforming catalysts allows us to conclude that the proposed method meets the requirements of an inventive step.

 Examples of specific uses of the method are given below.

Example 1
The catalyst AP-56 was deactivated, deactivated by prolonged use on non-hydrotreated raw materials, after 7 months of operation, containing in wt. platinum 0.55; fluorine 0.26; Y-alumina rest. After the feed was cut off, it was subjected to WASH treatment at a temperature of 500 ^o C for 12 hours, then oxidative regeneration was carried out in order to burn coke in a stream of nitrogen containing 3 vol. O ₂ , when the temperature rises from 250 to 500 ^o C.

Further, the catalyst containing 2.9 wt. sulfur, re-processed in a stream of Hash at a temperature of 530 ^o C and a pressure of 2.2 MPa for 24 hours. In this case, the analysis of the SHG before and after the reactors (1.5 and 3 mg / m ^3, respectively) showed a slight removal of sulfur from the catalyst in the form of hydrogen sulfide.

After hydrogen treatment, the catalyst was oxychlorinated by feeding dichloroethane in an amount of 0.8% by weight of the catalyst in a stream of nitrogen containing 3 vol. oxygen. Oxychlorination was carried out at a temperature of 520 ^o C for 2 hours, followed by exposure without supply of dichloroethane for 6 hours at a temperature of 510 ^o sC.

Hydrogen activation after oxychlorination was carried out in a stream of SHG containing 1.5 mg / m ³ H ₂ S at a temperature of 480 ^o C and a pressure of 0.7 MPa for 3 hours. Further, the pressure was increased to 2.2 MPa and held for 5 hours, followed by a decrease in pressure to 0.7 MPa with simultaneous blowing off of sulfur-containing VSG and filling the system with fresh VSG. The content of H ₂ S in the blown off WASH was 104 mg / m ³ .

The increase in pressure and the discharge of sulfur-containing WASH according to the above method was carried out repeatedly, while the content of H ₂ S in the deflated WASH was 81 msg / m ³ .

Hydrotreated fraction reforming 85-180 ^o C was carried out on an industrial plant at a temperature of 495 ^o C, a pressure of 3.0 MPa, a volumetric feed rate of 1.5 h ^-1 and a circulation rate of VSG 1200
nm ³ / m ³ raw materials. Under these conditions, stable catalysis was obtained with an octane rating of 77 points (m.m.) and a yield of 87.5 wt.

Example 2
The deactivated catalyst AP-56 was loaded into the reactor of the pilot plant, the composition of which is shown in Example 1. The catalyst was preliminarily subjected to the processing of SHG and oxidative regeneration under the conditions of Example 1 under industrial conditions.

The regenerated catalyst was treated in a stream of SHG at a temperature of 480 ^o C and a pressure of 2.0 MPa for 48 hours.

Analysis of the WASH for the content of hydrogen sulfide before and after the reactors: less than 1 and 3 mg / m ^3, respectively.

The oxychlorination of the catalyst was carried out in a stream of nitrogen containing 5 vol. oxygen and 0.5 wt. chlorine (by weight of the catalyst) at a temperature of 480 ^o C for 2 hours, followed by exposure without supply of dichloethane for 6 hours at a temperature of 500 ^o C.

Hydrogen activation of the catalyst was carried out in a stream of SHG containing less than 1 mg / m ^{3 of} hydrogen sulfide, at a temperature of 530 ^o C and a pressure of 0.5 MPa for 2 hours. Then, the pressure was increased to 2.5 MPa and held for 6 hours, followed by a decrease in pressure to 0.5 MPa with simultaneous blowing off of the contaminated VSH (H ₂ S content of 93 mg / m ³ ) and filling the system with fresh VSG.

The increase in pressure and the discharge of sulfur-containing WASH was performed 3 times, the hydrogen sulfide content after 2 and 3 of the discharge of WASH was 74 and 67 mg / m ^3, respectively. The reforming of the gasoline fraction 85-180 ^o C was carried out under the conditions of example 1.

 Stable catalysis was obtained with an octane number of 771 points (m.m.) and a yield of 87.5 wt.

Example 3 (comparative)
The activity of the deactivated catalyst AP-56 was restored according to example 2.

At the stage of hydrogen activation of the catalyst after oxychlorination at a temperature of 500 ^o C, a single increase in the pressure of the SHG was carried out from 0.5 to 2 MPa and its subsequent decrease to 0.5 MPa with a blow-off of the used SHG with a content of H ₂ S 96 mg / m ³ and filling the system fresh WASH and reforming in the conditions of example 1.

 A stable catalyst was obtained with an octane rating of 76.1 points (m.m.) and a yield of 87.5 wt.

 When reforming under the same conditions of Example 1 a fresh AP-56 catalyst, stable catalysis was obtained with an octane rating of 76.8 (m.m.) and a yield of 88 wt.

Example 4 (according to the prototype)
The deactivated catalyst AP-56, the composition of which is shown in example 1, was unloaded from the industrial reforming reactor, processed by the WASH at a temperature of 500 ^o C for 12 hours and subjected to oxidative regeneration at a temperature of 520 ^o C in a stream of nitrogen containing 5 vol. O ₂ .

The regenerated catalyst was loaded into the reactor of the pilot plant and re-treated with a concentration of H ₂ S 1 mg / m ³ at a temperature of 500 ^o C for 20 hours.

The reduced catalyst was subjected to oxychlorination with carbon tetrachloride fed to nitrogen containing 5 vol. O ₂ in an amount equivalent to 0.8% by weight of the catalyst. After oxychlorination, the catalyst was treated with SHG at a temperature rise of 350 to 500 ^o C, at a pressure of 0.7 MPa for 4 hours.

The hydrotreated gasoline fraction 85-180 ^° C. was subjected to reforming under the conditions of Example 1. A stable catalysis was obtained with an OC (76 m) of 87 points and a yield of 87.5 wt.

 Thus, the reactivation of sulfur-poisoned platinum-containing reforming catalysts by the proposed method (examples 1 and 2) can completely restore the activity of the catalysts to the level of activity of a fresh catalyst (see example 3).

 The effect obtained is associated with hydrogen reactivation after oxychlorination under conditions of periodic (at least 2 times) increase in the pressure of the second-harmless layer from 0.5-0.7 MPa to 2.2-2.5 MPa, followed by a decrease to 0.5-0.7 MPa with simultaneous blowing off of sulfur-containing WASH and filling of the reactor system with fresh WASH.

 A single recovery cycle (example 3) did not allow to restore the activity of the catalyst AP-56, as well as carrying out the method according to the prototype (example 4).

Claims (1)

A method of restoring the activity of a sulfur-poisoned platinum reforming catalyst, comprising treating the catalyst with a hydrogen-containing gas with an H ₂ S concentration of less than 2 mg / m ³ at 480 530 ^{° C.} , burning coke, re-purging with a hydrogen-containing gas, treatment with an organochlorine compound in an oxygen-containing medium and again with a hydrogen-containing gas , characterized in that the treatment with a hydrogen-containing gas after treatment with an organochlorine compound is carried out by periodic, at least 2 times, increasing the pressure from 0.5 0.7 to 2.2 2 , 5 MPa, holding for 5 6 hours, followed by a decrease in pressure to 0.5 0.7 MPa.