DD219396B1 - METHOD FOR THE OXYDATIVE REACTIVATION OF REFORMATING AND AROMATING CATALYSTS - Google Patents

Description

according to the known per se known oxidative removal of carbonaceous deposits in the presence of a halogen-transmitting and / or the formation of elemental halogen-promoting component or a corresponding component combination at oxygen partial pressures greater than 0.02 MPa, temperatures greater than 680K and halogen contents between 20 and 10000VoI. Be treated for at least one hour and then reduced in a conventional manner with hydrogen-containing gases at temperatures greater than 670 K.

Another essential feature of the process according to the invention is that the halogen-transferring and / or the elementary halogen-promoting components are constituents of the catalyst. As particularly effective components in the context of the invention, copper, chromium and manganese or the corresponding compounds in the range of 0.001 to 1.0 wt .-% have been found based on the catalyst composition. The reactant treatment gas used in the process of the present invention has molar ratios between water and hydrogen chloride equivalent to the halogen amount used of 1: 2 to 1: 100. Chlorine-containing hydrocarbons, such as, for example, carbon tetrachloride, chloroform, dichloroethane or hydrogen chloride or other chlorine-containing compounds, are preferably used as halogen-containing compounds. The inventive use of halogen-transferring and / or the formation of elemental chlorine-promoting components in addition to the excellent reactivation effect ensures that the resulting in the reactivation highly active catalyst centers in the supply of hydrocarbons not to the known unselective cleavage reactions and thus already in the initial phase of a catalytic reaction lead to partial damage to the catalyst. The process of the invention ensures virtually complete recovery of catalyst activity with a minimum number of reactivating treatment steps required. The conditions for these reactivating treatment steps can be varied within relatively wide limits and thus are applicable in an inverse manner. The use of the method according to the invention makes a targeted reactivation of the catalyst in individual reaction zones superfluous. For this reason, the method is particularly recommended for those processing processes in which a continuous regeneration of the catalyst is required.

Exemplary embodiments: Example 1

Three different catalysts (identified below as A, B and C) used for hydrocarbon conversion under typical reforming conditions were oxidatively freed from the carbonaceous deposits and subjected to a reactivation treatment. For this purpose, in each case 15 cm ^{3 of} carbon-free catalyst in the air stream containing 1000 ppm by volume of carbon tetrachloride or 1000 ppm by volume of carbon tetrachloride and 750Vol.-ppm water were treated over a period of four hours at the temperatures indicated in Tab.

The catalysts are characterized as follows:

Catalyst A is a commercially available Pt / Re catalyst based on a gamma Al ₂ O ₃ . Catalyst B and Catalyst C contain, in addition to analogous amounts of platinum and rhenium, as the halogen-promoting or elemental halogen-promoting component, 0.015 mass% Cu (Catalyst B) and 0.8 mass% Cr ₂ O ₃ (Catalyst C).

The reactivation effect achieved is by means of the metal dispersity characterized by the CO chemisorption capacity

marked (Table 1).

Tab. 1: CO chemisorption capacities of the catalyst patterns

Reaction temperature CO chemisorption values

in K in μmol / g

Fresh after reactivation

with catalyst

CCI ₄ CCI ₄ / H ₂ O

14.7 11.9 15.6

12.9 10.9 16.3

19.1 14.5 23.5

It can be clearly seen that - especially in the reactivation with carbon tetrachloride and water - higher dispersity plants are achieved on the catalysts B and C compared to the catalyst A.

Example 2:

The catalysts mentioned in Example 1 were used in a small-scale experimental apparatus under the conditions

Pressure 1.0MPa

Load 2.0 v / v-h

Ratio H ₂ / KW 5.5 mol / mol

Temperature 793-798 K

Catalyst volume 250 ml

with a desulphurised hydrocarbon fraction of the following characteristics

Boiling range 343-418 K

Paraffins 64.7Ma .-%

Naphthenes 29.3Ma .-%

Aromatics 6.0% by mass

Catalyst A 723 Catalyst B 723 Catalyst C 783

Comparatively tested. Performance criteria are liquid and aromatics yield. After a test period of about 150 hours, the catalysts are freed of carbonaceous deposits oxidatively and reactivated under the following conditions:

Pressure 1.0MPa

Temperature 753 K

Medium nitrogen with 5% by volume

Oxygen, 500 ppm by volume of carbon tetrachloride and 300 ppm by volume of water Duration 2 hours

Following reactivation, another activity test was performed under analogous conditions. The test results are given in Tab. 2.

Table 2: Result of the catalytic test catalyst B C A 78.3 81.1 Activity of the fresh catalyst (T = 793 K) 77.8 53.1 52.0 Liquid yield in% by mass 53.8 Aromatic yield in% by mass 77.9 80.2 Activity after reactivation (T = 798 K) 78.5 53.5 52.8 Liquid yield in% by mass 52.8 Aromatic yield in% by mass

The reactivation process using catalysts B and C leads to more favorable results.

Claims (2)

1. A process for the oxidative reactivation of reforming and aromatization catalysts - which consist of surface-rich and porous alumina moldings and contain at least two elements of the VII and VIII. Subgroup of the PSE in the concentration range of 0.1 to 1.0Ma .-% -after oxidative removal of carbonaceous deposits, with a reactivation gas containing nitrogen, oxygen, a halogen compound and water, which is reduced after reactivation of hydrogen-containing gases at temperatures greater than 670K, characterized in that the catalysts, in addition, a halogen-transmitting and / or the formation containing elemental halogen-promoting component or a corresponding combination of components are treated for at least one hour at temperatures above 680K with the reactivation gas whose oxygen partial pressure is greater than 0.02 MPa, its halogen concentration between 20 and 100 00 ppm by volume and the molar ratios between water and the halogen compound, based on the forming amount of hydrogen halide, of 1: 2 to 1: 100. 2. The method according to item 1, characterized in that as halogen-transmitting and / or the formation of elemental halogen-promoting components copper and / or chromium and / or manganese or the corresponding compounds in the range of 0.001 to 1.0Ma .-%, based on the composition of the catalyst can be applied. Process for the oxidative reactivation of reforming and aromatization catalysts Field of application of the invention The invention relates to a process for the reactivation of reforming and aromatization catalysts, which are used at elevated temperatures and pressures for hydrocarbon conversion and regenerated periodically or continuously. Characteristic of the known technical solutions Processes for the regeneration or reactivation of catalysts for the reforming or aromatization of hydrocarbon fractions are generally known and are used industrially in various designs. The specifics of the catalysts used for this purpose and the significant changes in the catalyst for the loss of activity necessitate that regeneration processes generally include measures for removing the carbonaceous deposits, for redispersing the active components present, optionally for adjusting the necessary halogen content and for reducing the catalyst. Although these basic operations of a reactivation process are fixed, a number of special process variants are known in which a combination of individual treatment steps, a beneficial effect on the catalyst properties is sought. An essential aspect of all measures is to achieve the most intensive possible interaction between the halogen compounds used and the catalyst or the catalyst components. DD-PS 121 716, for example, proposes a chlorinating treatment both in an oxidizing and in a reducing medium at different temperatures as a reactivation process. Multi-stage and thus simultaneously complex reactivation treatments are also the subject of other methods (DE-OS 2438 131, DD-PS 150 986). The chlorinating treatment of the catalyst can be carried out both before (DE-OS 2010 827, DD-PS 151 556) and after the removal of the carbonaceous deposits. However, the chlorination of carbon-containing catalysts is always associated with the risk that unfavorable metal dispersions can be formed by the formation of platinum carbonyl chlorides. The success of a reactivation is thus bound to the observance of strictly limited conditions. In order to achieve special effects between reactivation medium and catalyst, specific chlorination steps and conditions for the catalyst in the individual reaction zones of a reforming plant are prescribed, both different amounts of halogen (DD-PS 151 556) and different treatment temperatures and various halogen compounds (DD-PS 149 846). However, the reactivation effects which can be achieved with such processes are associated with the disadvantage of increased technical complexity and can not be used advantageously, for example, for reforming processes with continuous regeneration of the catalyst. Object of the invention The object was to improve the oxidative reactivation of reforming and aromatization catalysts in such a way that the use of these catalysts for hydrocarbon conversion, in particular for processes with continuous catalyst regeneration, is made possible in a very expedient manner. Explanation of the essence of the invention It was therefore the object to develop a process for the oxidative reactivation of reforming and aromatization catalysts, in which a virtually complete recovery of the catalyst activity is achieved by a minimum number of necessary treatment steps. This object has been achieved according to the invention by a process for the oxidative reactivation of reforming and aromatization catalysts, which consist of surface-rich and porous alumina moldings, at least two elements of VII. And VIII. Subgroup of the PSE in the concentration range of 0.1 to 1.0Ma. % and a more or less pronounced loss of activity