RU2529997C1 - Method of activating platinum-mordenite catalyst for hydroisomerisation of benzene-containing fractions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: described is a method of activating platinum-mordenite catalysts for hydroisomerisation of benzene-containing fractions and which is carried out at high temperature and pressure, successive treatment thereof in a current of dry air and reduction with hydrogen, wherein reduction is carried out in two steps.

EFFECT: high catalyst activity.

2 cl, 2 tbl, 8 ex

Description

The invention relates to methods for the activation of catalysts, in particular to the activation of platinum-mordenite catalysts for the hydroisomerization of benzene-containing fractions, and can be used in refineries and petrochemicals in the production of high-octane gasoline components.

Modern automobile gasolines have restrictions on the content of benzene, the proportion of which should not exceed 1% vol.

When using reformate as a basic component of motor gasoline, the task of reducing the benzene content is solved, for example, by separating the reformate into two fractions: heavy reformate and light reformate, in which all benzene is concentrated, after which the light reformate fraction is subjected to hydrogenation, and then isomerization separately or in a mixture with a straight-run fraction of C ₅ -C ₆ (RF patent 2091440, 2130962). The catalyst contains at least one metal from the group consisting of platinum, palladium and nickel on a support from a chlorinated mixture of eta-alumina and gamma-alumina in certain proportions or on a mordenite-containing support.

There is also known a method in which light reformate is immediately mixed with straight-run fraction C ₅ -C ₆ for the same purpose isomerized in the presence of a catalyst containing platinum and modernite with a Si / Al ratio of 5-50 (RF patent 2091441) .

A disadvantage of the known methods is the low octane number of the target product (78.1-81.5 points by the research method). In addition, the conversion of cyclic hydrocarbons contained in the light fraction of the reformate under severe conditions leads to increased opening of the cycles and enhanced cracking, resulting in a yield of hydroisomerizate of only 94.0-95.9 wt.%.

It is known that platinum-containing hydrogenation and hydroisomerization catalysts are pre-activated at elevated temperatures in air or an inert gas containing oxygen, and then in a hydrogen or hydrogen-containing gas (reduction of the catalyst). The activation of the catalysts in the known methods is carried out in such a way that after reduction at least 50 wt.% Of the total amount of metal must be in reduced form. In addition, when using a carrier from a chlorinated mixture of etha- and gamma-alumina after reduction with hydrogen, the catalyst is chlorinated.

A known method of hydroisomerization of light gasoline fractions on a solid acid catalyst containing a Group VIII metal, in which the catalyst is activated with a dry inert gas containing 0.1-3.0 vol.% Oxygen, at a pressure of 0.5-2.5 MPa, when heated to temperature 450-520 ° С with holdings for 3-24 hours every 50 ° С, cooled in a stream of inert gas without oxygen to a temperature of 100-120 ° С, replace inert gas with hydrogen, raise the pressure to 1.0-3.5 MPa and restore in a stream of hydrogen when the temperature rises to the temperature of the process (RF patent No. 2394804). The pressure at which the catalyst is reduced in the known methods is either lower or corresponds to the pressure at which the catalyst is subsequently operated.

The known method has limitations on the content of benzene in the feed (1.2 wt.%) And when the light reformate fraction is involved in the feed, the catalyst activity and the octane number of the motor fuel component are significantly reduced.

A known method of removing benzene from a light fraction of the reformate by hydroisomerization to methylcyclopentane (Maryshev VB, Mozhaiko VN Oil refining and petrochemicals, 9, 2005, p.9-10). The process is carried out in a medium of hydrogen-containing gas (HSG) at a temperature of 250-330 ° C and a pressure of 2.5-3.5 MPa, in the presence of a platinum-mordenite catalyst. The process is characterized by the almost complete removal of benzene along with the preservation of the octane number of the liquid product at its output - 96-98 wt.%. The catalyst is prepared and activated by the method (RF patent 2287369 - prototype), which includes the synthesis of a mordenite-containing carrier and the deposition of the active component - platinum, as well as heat treatment of the catalyst in air at temperatures up to 300 ° C and in dry hydrogen at a temperature of at least 500 ° C (500-600 ° C) for 2-3 hours.

A common feature of the known methods is carrying out catalyst reduction (activation of the catalyst in a hydrogen medium) in one stage by high-temperature processing of the catalyst at a constant pressure of hydrogen or VSG.

The disadvantage of activating the catalyst according to the method in accordance with the prototype is its insufficiently high activity. So, when hydroisomerization of the light fraction of reformate n.k. - 85 ° C at a temperature of 260 ° C, a pressure of 3.0 MPa, a volumetric feed rate of 3.0 h ^-1 and a molar ratio of hydrogen: feed 3: 1 after activation under the conditions of a prototype catalyst containing platinum in an amount of 0.3 wt. .% and mordenite with a silicate module M 20 in an amount of 30 wt.%, the octane number of hydroisomerizate is 75.9 points according to the research method (IOI).

The basis of the invention is the task of developing a method for activating a catalyst for hydroisomerization of benzene-containing fractions, which provides an increase in the octane number of the hydroisomerizate by choosing the conditions for its recovery.

To solve this problem, a method for the activation of a platinum-mordenite catalyst for hydroisomerization of benzene-containing fractions by sequential treatment in a stream of dry air at a temperature of up to 300 ° C and reduction with hydrogen or Hash at elevated temperature and pressure is proposed, the restoration is carried out in two stages: at the first stage, the restoration is carried out at a pressure of 1.0-1.5 MPa and a temperature increase at a speed of 10-15 ° C per hour to 280-300 ° C, in the second stage, the pressure is raised to 3.0-3.5 MPa, the temperature at a speed of 15-20 ° C in h As raise to 440-460 ° C and maintain the catalyst in these conditions for 4-6 hours.

To restore the platinum-mordenite catalyst, it is preferable to use the WASH reforming with a hydrogen concentration of at least 90 vol.%.

The salient features of the method are the reduction of the platinum-mordenite catalyst in two stages at different pressures of the circulating Hash; recovery initially at a pressure of 1.0-1.5 MPa and a temperature increase at a rate of 10-15 ° C per hour to 280-300 ° C, then at a pressure of 3.0-3.5 MPa and a temperature increase at a speed of 15- 20 ° C per hour to 440-460 ° C with exposure at this temperature for 4-6 hours.

A preferred feature is the use of a hydrogen-containing gas with a hydrogen concentration of at least 90 vol.%.

The authors found that the activation mode with two-stage reduction affects the change in the adsorption properties of the catalyst and the selectivity of the conversion of benzene to methylcyclopentane, which is reflected in an increase in the octane characteristic of the hydroisomerization products of benzene-containing fractions. In addition, the method allows you to remove adsorption water from the catalyst without reducing its mechanical strength. It was found that the implementation of activation at a pressure at both stages above the claimed interval does not lead to an increase in the positive effect, and at a lower one to a decrease in the activity of the catalyst. The performance of the catalyst is also deteriorating when changing the claimed temperature recovery intervals.

The activation of the catalyst for hydroisomerization of benzene-containing fractions is as follows. Freshly prepared or reactivated catalyst is placed in a reactor and dried in a stream of dry air at a temperature of 100-300 ° C. Then the reactor is cooled, purged with inert gas until there is no oxygen at the outlet of the reactor, and VGF reforming with a hydrogen concentration of at least 90 vol.% Or electrolytic hydrogen is obtained until a pressure of 1.0-1.5 MPa is reached. After that, they begin to restore the catalyst in a stream of dry Wash or hydrogen in two stages; in the first stage, the temperature is gradually increased at a speed of 10-15 ° C per hour to 280-300 ° C, in the second stage, the pressure is raised to 3.0-3.5 MPa and at this pressure the temperature is increased at a speed of 15-20 ° C hour to 440-460 ° C. At a temperature of 440-460 ° C produce exposure for 4-6 hours. The catalyst is tested in a typical pilot installation “on the duct”, where the light fraction of the NK-85 reformate containing almost all reformate benzene is used as raw material. Conditions for hydroisomerization: pressure 2.5-3.0 MPa, temperature 250-320 ° C, bulk feed rate 2.0-3.0 h ^-1 and the molar ratio of hydrogen: feedstock 3-4: 1.

The obtained hydroisomerizate practically does not contain benzene and has an IOC from 78.0 to 80.5 points; it can be used as a component of gasoline with improved operational and environmental indicators. Activation of the same catalyst, but with the restoration of a constant Wash (3.2 MPa) at a constant pressure, results in a catalyst with lower activity, while the ROS of the target product is only 75.6 points.

The achieved technical results were obtained by varying the activation mode of the hydroisomerization catalyst (table 2).

The activation method of the hydroisomerization catalyst for benzene fractions is illustrated by the following examples.

Example 1

To prepare a catalyst for hydroisomerization of benzene-containing fractions, powdered mordenite in hydrogen form, having a silicate module M = 20, is mixed with Catapal A pseudoboehmite. The mordenite content in the mixture with the binder is 25 wt.%.

The mixture is peptized with a solution of nitric acid, turned into a paste and extruded, and the obtained extrudates of the carrier are calcined in air at a temperature of 450-600 ° C, after which the carrier is impregnated with an aqueous solution of platinum chloride and acetic acids based on the content of platinum in the catalyst of 0.3 wt.%.

The catalyst is loaded into the reactor and dried in a stream of dry air when the temperature rises to 300 ° C. Then the reactor is cooled, purged with an inert gas until there is no oxygen, and VGF reforming with a hydrogen concentration of 90 vol.% Is collected until a pressure of 1.0 MPa is reached. After that, the recovery of the catalyst in a dry stream of VSG is started in two stages: in the first stage, the temperature is gradually increased at a rate of 15 ° C per hour to 300 ° C, in the second stage, the pressure is raised to 3.2 MPa and the temperature is increased at a speed 20 ° C per hour to 450 ° C. At a temperature of 450 ° C produce exposure for 6 hours.

The catalyst is tested in a typical pilot installation "on the duct", where the light fraction of reformate NK-85 is used as raw material, the composition of which is given in table 1. Conditions for the hydroisomerization process: pressure 3.0 MPa, temperature 260 ° C, bulk feed rate 3.0 h ^-1 and a molar ratio of hydrogen: feed 3.

The results of catalytic tests: IOC of stable hydroisomerizate-target product - 80.5 points, the residual content of benzene in it - 0.1 wt.%. Both indicators indicate a high activity of the catalyst activated by the proposed method.

Example 2

The hydroisomerization catalyst prepared according to example 1 is loaded into the reactor and dried in a stream of dry air when the temperature rises to 300 ° C. Then the reactor is cooled, purged with an inert gas until there is no oxygen, and VGF reforming with a hydrogen concentration of 90 vol.% Is collected until a pressure of 1.5 MPa is reached. After that, the recovery of the catalyst in a dry stream of Hash proceeds in two stages: in the first stage, the temperature is gradually increased at a rate of 10 ° C per hour to 280 ° C, in the second stage, the pressure is raised to 3.2 MPa and the temperature is increased at a speed 15 ° C per hour to 440 ° C. At a temperature of 440 ° C produce exposure for 4 hours. The catalyst is tested in a typical pilot installation "on the duct", where the light fraction of reformate NK-85 is used as raw material, the composition of which is shown in table 1. The conditions for the hydroisomerization process are similar to those described in example 1.

The results of catalytic tests: IOC of stable hydroisomerizate - the target product - 78.0 points, the residual content of benzene in it - 0.2 wt.%.

Example 3

The hydroisomerization catalyst prepared according to example 1 is loaded into the reactor and dried in a stream of dry air when the temperature rises to 300 ° C. Then the reactor is cooled, purged with an inert gas until there is no oxygen and electrolytic hydrogen is collected (H ₂ - 100 vol.%) Until a pressure of 1.5 MPa is reached. Further activation of the hydroisomerization catalyst is carried out analogously to example 2.

The catalyst is tested in a typical pilot installation "on the duct", where the light fraction of reformate NK-85 is used as raw material, the composition of which is shown in table 1. The conditions for the hydroisomerization process are similar to those described in example 1.

The results of catalytic tests: IOC of stable hydroisomerizate - the target product - 78.3 points, the residual content of benzene in it - 0.1 wt.%. Thus, the use of SHG with a hydrogen concentration above 90 vol.% Leads to an additional increment of the positive effect of the proposed method.

Example 4

The hydroisomerization catalyst prepared according to example 1 is loaded into the reactor and dried in a stream of dry air when the temperature rises to 300 ° C. Then the reactor is cooled, purged with an inert gas until there is no oxygen, and VGF reforming with a hydrogen concentration of 90 vol.% Is collected until a pressure of 1.2 MPa is reached. After that, the recovery of the catalyst in a dry dry gas stream is started in two stages: in the first stage, the temperature is gradually increased at a rate of 15 ° С per hour to 300 ° С, in the second stage, the pressure is raised to 3.0 MPa and the temperature is increased at a speed 20 ° C per hour to 460 ° C. At a temperature of 460 ° C produce exposure for 6 hours. The catalyst is tested in a typical pilot installation "on the duct", where the light fraction of reformate NK-85 is used as raw material, the composition of which is shown in table 1. The conditions for the hydroisomerization process are similar to those described in example 1.

The results of catalytic tests: IOC of stable hydroisomerizate - the target product - 80.2 points, the residual content of benzene in it - 0.1 wt.%

Example 5

The hydroisomerization catalyst prepared according to example 1 is loaded into the reactor and dried in a stream of dry air when the temperature rises to 300 ° C. Then the reactor is cooled, purged with an inert gas until there is no oxygen, and VGF reforming with a hydrogen concentration of 90 vol.% Is collected until a pressure of 1.2 MPa is reached. After that, the recovery of the catalyst in a dry stream of Hash proceeds in two stages: in the first stage, the temperature is gradually increased at a rate of 10 ° C per hour to 280 ° C, in the second stage, the pressure is raised to 3.5 MPa and at this pressure the temperature is increased at a speed 15 ° C per hour to 440 ° C. At a temperature of 440 ° C produce exposure for 4 hours. The catalyst is tested in a typical pilot installation "on the duct", where the light fraction of reformate NK-85 is used as raw material, the composition of which is shown in table 1. The conditions for the hydroisomerization process are similar to those described in example 1.

The results of catalytic tests: IOC of stable hydroisomerizate - the target product - 79.1 points, the residual content of benzene in it - 0.1 wt.%.

Example 6 (comparative)

The hydroisomerization catalyst prepared according to example 1 is loaded into the reactor and dried in a stream of dry air when the temperature rises to 300 ° C. Then the reactor is cooled, purged with an inert gas until there is no oxygen, and VGF reforming with a hydrogen concentration of 90 vol.% Is collected until a pressure of 3.2 MPa is reached (in contrast to Example 1). After that, they begin to restore the catalyst in a stream of dry HSG in two stages: in the first stage, the temperature is gradually increased at a speed of 15 ° C per hour to 300 ° C, in the second stage at the same pressure of 3.2 MPa, the temperature is increased at a rate of 20 ° C per hour to 450 ° C. At a temperature of 450 ° C produce exposure for 6 hours. The catalyst is tested in a typical pilot installation "on the duct", where the light fraction of reformate NK-85 is used as raw material, the composition of which is shown in table 1. The conditions for the hydroisomerization process are similar to those described in example 1.

The results of catalytic tests: IOC of stable hydroisomerizate - the target product - 75.6 points, the residual content of benzene in it - 0.3 wt.%. Thus, activation of the catalyst with both stages of reduction under constant pressure does not increase the activity of the catalyst for hydroisomerization of benzene fractions.

Example 7 (comparative).

The hydroisomerization catalyst prepared according to example 1 is loaded into the reactor and dried in a stream of dry air when the temperature rises to 300 ° C. Then the reactor is cooled, purged with an inert gas until there is no oxygen, and VGF reforming with a hydrogen concentration of 90 vol.% Is collected until a pressure of 3.2 MPa is reached. After that, they begin to restore the catalyst in a stream of dry WASH in two stages; in the first stage, the temperature is gradually increased at a speed of 15 ° C per hour to 300 ° C, in the second stage, the pressure is reduced to 1.5 MPa and at this pressure the temperature is increased at a speed of 20 ° C per hour to 450 ° C. At a temperature of 450 ° C produce exposure for 6 hours. The catalyst is tested in a typical pilot installation "on the duct", where the light fraction of reformate NK-85 is used as raw material, the composition of which is shown in table 1. The conditions for the hydroisomerization process are similar to those described in example 1.

The results of catalytic tests: IOC of stable hydroisomerizate - the target product - 75.8 points, the residual content of benzene in it - 0.5 wt.%. Thus, the specified sequence of stages of activation of the catalyst is an essential feature of the proposed method.

Example 8 (known)

The hydroisomerization catalyst prepared according to example 1 is loaded into the reactor and dried in a stream of dry air when the temperature rises to 300 ° C. Then the reactor is cooled, purged with an inert gas until there is no oxygen, and VGF reforming is collected with a hydrogen concentration of at least 90 vol.% Until a pressure of 2.5 MPa is reached. After that, they begin to restore the catalyst in a stream of dry VSS, which is carried out in one stage (at constant pressure) by gradually increasing the temperature at a rate of 15 ° C per hour to 500 ° C, followed by exposure at this temperature for 6 hours. The catalyst is tested in a typical pilot installation "on the duct", where the light fraction of reformate NK-85 is used as raw material, the composition of which is shown in table 1. The conditions for the hydroisomerization process are similar to those described in example 1.

The results of catalytic tests: IOC of stable hydroisomerizate - the target product - 75.9 points, the residual content of benzene in it - 0.3 wt.%. The catalyst has a reduced activity.

Table 1 The composition of the reformate fraction NK-85 ° C - the raw material of the hydroisomerization process No. Indicator Value one

Density, $$d_{\mathrm{four}}^{\mathrm{twenty}}$$

0.697 2 Hydrocarbon composition, wt.% 3 isobutane iso-C ₄ 0.2 four n-butane nc ₄ 1,0 5 isopentane iso-C ₅ 9.1 6 n-pentane nc ₅ 7.3 7 2,2-dimethylbutane 2,2 dmb 2.1 8 cyclopentane CPU 0.3 9 2,3-dimethylbutane 2,3-dmb 1.8 10 2-methylpentane 2 megapixel 10.7 eleven 3-methylpentane 3 megapixel 8.1 12 n-hexane nc ₆ 9.9 13 2,2-dimethylpentane 2.2 dmp 1.4 fourteen methylcyclopentane Mcp 3.0 fifteen 2,4-dimethylpentane 2,4 dmp 1.9 16 benzene B 19,4 17 2-methylhexane 2 mg 7.6 eighteen cyclohexane TG 1.8 19 2,3-dimethylpentane 2,3-dmp 3.0 twenty 3-methylhexane 3 mg 7.5 21 dimethylcyclopentanes ∑ dmtsp 0.8 22 n-heptane nc ₇ 2.0 23 toluene T 1,1 24 IOCH (calculated) 74.9 25 Bromine number, g Br _2/100 g 1,1

table 2 Test conditions and results Process conditions: Temperature 260 ° C;
Pressure 3.0 MPa;
Volumetric speed 3.0 h ^-1 ;
The molar ratio of H ₂ : CH is 3: 1. №№ 1st stage of recovery 2nd stage of recovery IOI of the target product The benzene content, wt.% Note R, MPa T, ° C R, MPa T, ° C one 1,0 300 3.2 450 80.5 0.1 2 1,5 280 3.2 440 78.0 0.2 3 1,5 280 3.2 440 78.3 0.1 Electrolytic hydrogen four 1,2 300 3.0 460 80.2 0.1 5 1,2 280 3,5 440 79.1 0.1 6 (comparative) 3.2 290 3.2 450 75.6 0.3 Constant pressure 7 (comparative) 3.2 300 1,5 450 75.8 0.5 Reverse sequence 8 (famous) 2,5 500 - - 75.9 0.3

Claims (2)

1. A method of activating a platinum-mordenite catalyst for hydroisomerization of benzene-containing fractions by sequential treatment in a stream of dry air at a temperature of up to 300 ° C and reduction with hydrogen or a hydrogen-containing gas at elevated temperature and pressure, characterized in that the reduction is carried out in two stages; in the first stage, the recovery is carried out at a pressure of 1.0-1.5 MPa and an increase in temperature at a rate of 10-15 ° C per hour to 280-300 ° C, in the second stage, at a pressure of 3.0-3.5 MPa and an increase temperature at a speed of 15-20 ° C per hour to 440-460 ° C with exposure at this temperature for 4-6 hours. 2. The method according to claim 1, characterized in that the recovery of the platinum-mordenite catalyst is carried out with a hydrogen-containing reforming gas with a hydrogen concentration of at least 90 vol.%.