Method of regeneration of reforming catalysts on alumina or sulphonated aluminium oxide

 

(57) Abstract:

The invention relates to the refining and can be used for regeneration of the catalyst for reforming of gasoline fractions. Regeneration of reforming catalysts include hydrogen activation, burning coke, oxidative chlorination, oxidation and calcining the recovery processing catalysts on one of the stages of sulfur-containing compounds to achieve the concentration of sulfate ion before restoring 0.15 to 3 wt.%, later after the burning of coke or after oxidative chlorination process, the catalyst is sulfur-containing compounds in the environment circulating the hydrogen-containing gas at 400 - 200oC. the Proposed method allows you to save the composition of the catalyst required amount of sulfur in the form of sulfate ion, which increases the activity and stability of catalyst. table 2., 2 Il.

The invention relates to the field of oil refining, and in particular to methods of regeneration of catalysts for reforming of gasoline fractions.

As the reforming process is complicated by the catalyst composition by introducing additives governing specific catalytic functions.

Base catalysis is strengthening and regulating the acidity of the carrier in the catalyst composition is injected acid promoter - fluorine or chlorine.

Most currently used catalysts include metal promoter is rhenium, tin, cadmium, zinc and others. The purpose metal promoters - improved stability of catalysts or by hydrogenation of polycyclic structures precursor of coke, or due to the redistribution of coke on the catalyst surface by loosening lock active metal centers and improve the overall koksuemosti catalysts (G. N. Maslansky, R. N. Shapiro Catalytic reforming of gasolines. Ed. Chemistry, 1985, S. 94-104).

On the metal centers of reforming catalysts, particularly catalysts containing rhenium, in addition to the basic reactions of dehydrogenation of naphthenes and dehydrocyclization paraffins are the hydrogenolysis reaction is the decomposition of the hydrocarbon feedstock to methane, accompanied by coke deposits directly on the metal centers with the deactivation of the catalyst. To suppress hydrogenolysis at the start of fresh and regenerated catalysts them is treated with hydrogen sulfide or sulfur compounds, dosing of these agents in a stream of hydrogen containing gas at the stage of recovery ( at the final stage of production of hydrogen sulfide.

Significant widespread industrial reforming catalysts, containing in its composition of sulfate ion (patent USSR N 775880, publ. 07.02.83). When you run such catalysts is the recovery of aluminum sulfate, the resulting sulfide blocks the active metal centers and suppress hydrogenolysis.

The sulfate ion introduced into the catalyst during its manufacture, is fully used at initial start up and should be re-introduced into the catalyst composition. This disadvantage is eliminated in the closest analogue of the proposed method (patent USSR N 1359957, publ. 27.12.96 - prototype).

Method for regenerating catalyst for the prototype is shown in Fig.1. The entire regeneration process is divided into 8 stages, and processing of sulfur-containing catalyst compounds may be produced by any of the first seven stages so that completion of the entire cycle of the regenerated catalyst contained sulfated alumina according to the following reaction scheme:

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So, if the processing of the catalyst organo-sulfur compounds (R1-S-R2) is because at the end of the commodity cycle, either at the stage of hydrogen activation (Fig. 1, POS.the CIO oxidation of sulfide sulfur to form sulfur oxides and fixation of their media.

On oxidation stages (Fig. 1, POS.4-6) possible supply of various sulfur compounds, including oxides, with catalysers of them on the catalyst and direct fixation media. Possible treatment of the catalyst in the intermediate stages for the circulation of nitrogen with a flow of hydrogen sulfide on the stage (Fig.1, POS.3) or sulfur oxides at the stage (Fig.1, POS.7).

Acarnania catalysts on the oxidation stages (Fig.1, POS.4-6) requires distributed feed sulfur compounds and may be exercised during the regeneration of the catalyst out of the reactor in a rotary or belt furnaces.

On the reforming units are treatment options of the catalyst with hydrogen sulfide or sulfur compounds in the raw end of the cycle during hydrogen activation (Fig.1, POS.1-2).

The disadvantages of this method is that during the subsequent oxidation stages of regeneration (burning coke, 300 - 500oC, 60-80 hours; oxidative chlorination, 500-520oC 4-8 hours; oxidative calcination 520oC, 4-8 hours) the sulfur oxides produced by the combustion of adsorbed hydrogen sulfide, not only absorbed by the alumina, but also largely removed from the gases regenerat who offered.

The aim of the invention is to increase the activity and stability of reforming catalysts containing platinum or platinum and metallic promoters, halogen and media - alumina or sulfated alumina.

This goal is achieved through the regeneration of catalysts comprising hydrogen activation, burning coke, oxidative chlorination, oxidation and calcining the recovery processing catalysts on one of the stages of sulfur-containing compounds to achieve the concentration of sulfate ion in the catalyst before recovery of 0.15 to 3.0 wt.% and additional processing catalysts by sulfur-containing compounds in the environment circulating the hydrogen-containing gas at a temperature of 400-200oC after burning coke or after oxidative chlorination.

A distinctive feature of the proposed method is the treatment of the regenerated catalyst after burning coke or oxidative chlorination of hydrogen-containing gas with a sulfur-containing compound at a temperature of 400-200oC.

It should be noted that the procedure for the regeneration of reforming catalysts of the prototype and the proposed method gives the position is revom cycle, in the first stage of reforming collects the products of hydrogen sulfide corrosion, in particular the iron sulfides FeSxthat during regeneration and subsequent commodity cycle are a constant source of poisoning of the catalyst (R. N. Shapiro, B. B. Zharkov, G. A. Listokin, Chem. and technology of fuels and oils, 1984, No. 1, S. 12-14). For complete removal of sulfur from the catalyst reforming the legislators (USSR author's certificate N 1720708, publ. 23.03.92), introduces an additional processing stage catalyst, the hydrogen-containing gas between stages of burning coke and oxychlorination process. Processing is performed by gas with a hydrogen content of 90 to 100 mol.% with hydrogen sulfide content not more than 1.5 mg/nm3at a temperature of 500-520oC, flow 20-50 hours, i.e. in conditions very different from the conditions dosed acarnania catalyst by the proposed method.

Analysis of the known technical solutions in the field of regeneration of reforming catalysts indicates absence of these symptoms that are similar to salient features of the proposed method, i.e. the compliance of the proposed technical solutions to the requirements of inventive step.

Offer sposaitalia gas, lower temperature, turn off the supply of raw materials, free the system reforming of gasoline.

Hydrogen activation (Ref.2) are provided at the circulation of the hydrogen-containing gas with the rise of temperature to 480-500oC. the Purpose of the operation - desorption of hydrocarbons from the catalyst.

At the next stage (Ref.3) remove the hydrogen and gaseous hydrocarbons, the system is filled with nitrogen.

Burning coke (POS.4) are provided at the circulation of nitrogen in the stream which is dosed air. The temperature of the burning coke 300-500oC, the oxygen concentration gradually increases from 0.5 to 5.0 vol.%. Usually after this stage the installation is cooled and conduct internal inspection of reactors, overload and partial replacement of the catalyst, the repair works.

As shown by our studies, treatment of the catalyst sulfur compounds after burning coke gives significantly better results than the method on the prototype.

For this treatment (Ref.4A) the system is washed with nitrogen fill the hydrogen-containing gas and in terms of circulation, the temperature was raised to 400oC. Next to the entrance to the reactor serves the estimated amount of the organo-sulfur compounds and within 2-8 hours spend sulfid-200oC increases the efficiency of processing.

Then the system is washed with nitrogen, served in the air and at a temperature of 500-520oC, the oxygen concentration 3-10 vol.% spend oxidative chlorination of the catalyst with a flow of 0.8-1.0% chlorine by weight of the catalyst (Ref.5). As gloriously reagents used organochlorine compounds (carbon tetrachloride, dichloroethane, and others). Time oxychlorination process 2-8 hours.

If the installation is not carried out maintenance work after the burning of coke, sulfatirovnie catalyst may be carried out after the oxychlorination process (Ref. 5A). Additional operations are the same as in the case of POS.4A. For oxidative chlorination (POS.5) or solifidianism catalyst (Ref.5A) are oxidizing calcination (POS.6), at a temperature of 500-520oC, the oxygen concentration of 5-10 vol.%, the feeding of 0.2% chlorine (in the form of organochlorine compounds). Time oxidative calcination 4-8 hours. Then the system of the reformer is cooled, washed with nitrogen (Ref.7), take everything and pursue recovery of the catalyst in the range of 200-400oC (Ref.8). At a temperature of 400-430oC serves hydrotreated feedstock and installation of output for a given technological regime.

The advantage CLASS="ptx2">

The prototype between the treatment of the catalyst is sulfur-containing compounds and the start catalyst 80-100 hours is in an oxidizing atmosphere at high temperature. In the proposed method the residence time of the catalyst under these conditions is reduced to 4-16 hours. This solution allows you to save the composition of the catalyst required amount of sulfur in the form of sulfate ion, which increases the activity and stability of catalyst.

Examples of industrial applicability of the proposed method are given below (see tab. 2).

Example 1.

Industrial tri-reactor the catalytic reforming unit using a combined loading of the catalysts are given in table.1.

The facility has operated in the mode of providing catalyzate with an average octane rating of 93.2 item on the research method.

The average characteristics of the processed raw materials: the limits of boiling 90-175oC, the content of aromatics 8.0 wt.%, naphthenes of 33.0 wt.%) paraffins of 59.0 wt.%; the octane number of 56 points; a sulfur content of less than 1 mg/kg

Technological mode of reforming: a pressure of 25 kg/cm2consumption of raw materials 160-170 m3/h, the flow rate of the circulating water is equal to 492oC, the concentration of hydrogen in the circulating SIV 82 vol.%, the resultant catalysate equal 85,0 wt.%.

As testing of the catalyst to maintain the octane number of constant temperature at the inlet to the reactor is increased to 505oC, the concentration of hydrogen is reduced to 72%, the resultant catalysate is reduced to 83.0 wt.%.

After 11 months of work at the facility conduct the planned regeneration of the catalyst.

After the termination of the supply of raw materials at 450oC catalyst process of circulating the hydrogen-containing gas with the rise of temperature up to 480oC, then the installation of cool, everything is replaced by nitrogen, the temperature is again increased to 350oC discharge air and spend burning coke with a gradual rise of temperature up to 500oC.

After the burning of coke the catalyst in the reactor is cooled, rinsed with nitrogen and the section of the reformer is stopped for repairs.

After completion of the repairs of the reactor rinsed with nitrogen, filled the hydrogen-containing gas, the temperature of the circulation gas is increased up to 400oC and at this temperature out acarnania catalyst. In the flow of everything for entry into the first reactor for 6 hours serves 460 liters of sulfur reagent - mixture dialky the transportation reagent in terms of sulphur 0.3 wt.% the weight of catalyst in the reactor.

After acarnania and cooling of the catalyst replace everything on the nitrogen at 300oC serves the air and increase the temperature to 500 - 520oC, by setting the oxygen concentration of 10 vol.%. In these conditions hold for the oxidative chlorination of the catalyst. Within 3-4 hours at the entrance to each reactor was dotirovala carbon tetrachloride based feed 1% chlorine by weight of catalyst in each reactor. Then at a temperature of 520oC and oxygen concentration of 10 vol.% spend the oxidative calcination of the catalyst dosage through the first reactor of 0.2% chlorine by weight of the catalyst. The duration of calcination for 6 hours.

After baking, reduce the temperature to 100oC flush the system with nitrogen, substituted nitrogen on everything, restore the catalyst and served raw.

In the commodity cycle unit operated in a mode similar to that described above (with a pressure of 25 kg/cm2, the volumetric feed rate of 1.5 h-1the ratio of circulating SIV - 1200 nm3/m3of catalyst per hour).

The cycle duration was 12 months, with an average octane level 93.5 points.

The inlet temperature in the reactor at the beginning of the cycle 495oC, at the end 510oC, the concentration of water is tx2">

Thus, on a fresh boot catalysts primary activity is the temperature of the receiving catalyzate with an octane rating of 93.5 item amounted to 492oC, and the stability of the catalyst is the rate of rise of temperature of the reformer - was equal to 1.2 deg./months.

The catalyst regenerated by the proposed method had an initial activity of 495oC and stability of 1.25 deg./months.

Example 2.

The regeneration of catalysts in the installation of the reforming is carried out in the same sequence as described in example 1, except that the activation of the catalyst with a mixture of diallyldisulfide are not at a constant temperature of 400oC, and the temperature range of 400-200oC. the Flow of the reagent lead through the first reactor and 6 hours lower the temperature in the first reactor from 400 to 300oC, and the second and third reactors 400oC to 200oC. Total dosage in terms of sulphur is retained, as in example 1, 0.3% by weight of the catalyst.

In the commodity cycle unit operated in a mode of example 1.

The cycle duration was 14 months, with an average octane level 93.5 points. The inlet temperature in the reactor at the beginning of the cycle 490oC, at the end of the cycle 505o

Thus, acarnania catalysts in the proposed temperature range 400-200oC helps lower the initial temperature of the reformer to 490oC and a decrease in the rate of deactivation of the catalyst to 1.1 deg./months.

Example 3.

The regeneration of catalysts in the installation of the reforming is carried out in the same sequence as in example 2, only acarnania catalyst in the medium circulating SIV is carried out after the stage of oxidative chlorination. The setup is cooled to 100oC, flue gases displace nitrogen, accept everything, increase the temperature to 400oC and start acarnania catalyst.

In the flow of circulating SIV with hydrogen concentration 90 - 70% vol. for entry into the first reactor for 4 hours serves 330 litres of technical ethyl mercaptan (TU 6-02-511-80, C2H2S; the sulfur content of 48 wt.% or 0,41 kg/liter). Dosage of ethyl mercaptan in terms of sulphur is 0.2% by weight of the catalyst in all three reactors. As in example 2, the temperature in the first reactor for 4 hours reduced to 300oC, and the second and third reactors 200oC.

Then reduce the temperature to 100oC, washed installation of nitrogen, increase the temperature to all the calcining, as in example 1. Followed by cooling installation, flushing with nitrogen, accepting everything, recovery of the catalyst and the raw material feeding.

The duration of the subsequent commodity cycle was 17 months, with an average octane level 93.5 points.

The inlet temperature in the reactor at the beginning of the cycle 490oC at the end of the cycle 508oC, the concentration of hydrogen in the beginning of the cycle of 84 vol.%, at the end of the cycle 70 vol.%, the resultant catalysate in the beginning of the cycle 86,0 wt.%, at the end of the cycle of 84.0 wt.%.

The stability of the catalyst is the rate of deactivation was 1.05 deg./months.

Example 4 (the prototype).

The regeneration of catalysts in the installation of reforming described in example 1 is made in the manner specified in the prototype - patent N 1359957.

After the termination of the supply of raw materials catalysts for 6 hours are processed the hydrogen-containing gas with a hydrogen content of 50-70 vol.% at a temperature of 480oC. Then the temperature is reduced to 400oC and is activated catalyst gray, what to log in the first reactor is fed 460 liters of diallylsulfide that is 0.3% sulfur by weight of the catalyst in all reactors.

Further regeneration includes replacement of all h is the hydrogen-containing gas to pass to the commodity cycle.

The facility has operated in a mode similar to that described in example 1. The octane number is maintained at the level 93,0-93.5 item on the research method.

In the beginning of the cycle (first 10 days), the inlet temperature in the reactor is 500oC, the concentration of hydrogen 78%. After 10 months the commodity cycle ends when the inlet temperature in the reactor 515oC, the concentration of hydrogen in everything is 68%. The resultant catalysate for 10 months. dropped to 83.0 85.0 wt.%.

The stability of the catalyst in the present cycle was 1.5 degrees. /month.

Method of regeneration of reforming catalyst on aluminum oxide or sulfonated aluminum oxide containing platinum metal promoters and halogen, including stage hydrogen activation, the burning of coke, oxidative chlorination, oxidation calcination and recovery treatment of the catalyst at any stage of sulfur-containing compounds to the concentration of sulfate ion in the catalyst before recovery of 0.15 to 3.0 wt.%, characterized in that between stages of burning coke and oxidative chlorination or between stages of oxidative chlorination and oxidation calcination the catalyst additionally

 

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