RU2081151C1 - Method of catalytic reforming of gasoline fractions - Google Patents

Abstract

FIELD: gasoline production. SUBSTANCE: process is conducted on highly sulfur- sensitive platinum-rhenium catalyst at 460-540 C using preliminary adsorption purification of raw material by way of passing it with hydrogen through a bed of platinum-containing catalyst and then through bed of manganese oxide adsorbent at 340-460 C, said platinum- containing catalyst being arranged in purification zone in two or more layers and additional catalyst layers being located in the bed or after the bed of manganese oxide adsorbent. Advantageously, additional layer of platinum-containing catalyst is placed after at least 1/3 volume of manganese oxide adsorbent. EFFECT: enhanced efficiency of catalytic reforming even with elevated content of sulfur and naphtene compounds in raw material. 2 cl, 1 tbl

Description

 The invention relates to oil refining, and in particular to a process for the catalytic reforming of gasoline fractions in order to produce high-octane gasolines, and can be used in refineries and petrochemicals.

Platinum reforming catalysts are susceptible to sulfur poisoning from raw materials. For platinorenievyh catalysts in which the rhenium content is higher than that of platinum, the sulfur content in the raw material is limited to 0.5 million ^-1 and a maximum stability is achieved when the sulfur content is 0.1 million ^-1 and less than [1] for reforming catalysts, containing platinum deposited on an alkaline or alkaline earth zeolite L, the sulfur content is limited to 0.02-0.05 ppm ^-1 [2-4]
The usual way to clean sulfur reforming feedstocks is to hydrotreat them using alumina-nickel (cobalt) molybdenum catalysts. It provides a reduction in the sulfur content in gasoline to 0.5-10 million ^-1 [5] further reduction of residual sulfur can be achieved only by adsorption methods, and the best one is the adsorbent of sulfur compounds oksidnomargantsevy adsorbent.

A known method [6] in which pre-hydrotreated raw materials are passed through an oxide-manganese adsorbent in a mixture with a hydrogen-containing reforming gas containing hydrogen sulfide at a temperature of 340-460 ^o C, a pressure of 1-5 MPa, a molar ratio of hydrogen / hydrocarbons equal to 1-30 . Under these conditions, the adsorbent absorbs sulfur compounds from raw materials and hydrogen sulfides from a hydrogen-containing gas. Additionally purified raw materials are subjected to reforming under normal conditions. There is also known a method which provides for additional purification by passing raw materials with hydrogen at 340-460 ^o C, first through a layer of a low-sensitivity platinum-containing catalyst, and then through a layer of potassium alumina [2] or zinc oxide [3] adsorbent. The purified stream is then directed to the reforming zone.

 A disadvantage of the known methods is the unsatisfactory octane characteristics of reforming products (not more than 96.3 points according to the research method).

The closest in technical essence and results to the claimed method is a method of catalytic reforming on a highly sensitive to sulfur catalyst [4-prototype] according to which raw materials with hydrogen are preliminarily passed through a sulfur removal zone, including a layer of platinum-containing catalyst, and then a layer of manganese oxide adsorbent. Catalytic reforming is carried out under ordinary conditions: temperature 460-560 ^o C and pressure up to 5 MPa, preferably up to 2 MPa. Purification of sulfur is carried out by passing the raw material through a layer of a platinum-containing catalyst and manganese oxide adsorbent at lower temperatures, at which the reforming reactions proceed to a small extent.

Example 1 [4] as a platinum-containing catalyst used alyumoplatinoolovyanny catalyst in the purification zone the temperature is 370 ^o C. The sulfur content in the purified liquid product is less than 0.1 million ^-1, which allows the use of highly sensitive reforming catalyst as catalysts and catalyst vysokorenievye containing platinum on zeolite L in alkaline and alkaline earth form.

The known method is not effective enough, since it is limited by the quality of the raw materials in terms of sulfur content and hydrocarbon composition. Essentially, the known method is intended for the reforming process with the purification of raw materials from small (0.5-1 mln ^-1 ) to very small (less than 0.1 mln ^-1 ) containing sulfur. From example 1 it follows that when working on raw materials containing 2-4.3 million ^-1 sulfur, a breakthrough of sulfur occurs, and the unloaded adsorbent in the upper layer contains 11.4 wt. sulfur, and in the lower layer of 4.64 wt. sulfur. Thus, under these conditions, the adsorbent must be unloaded, far from having exhausted its full sulfur intensity. The known method is also intended for reforming preferably paraffinic feedstocks, for example gasoline raffinates or gasoline fractions in which paraffin hydrocarbons predominate. When reforming the same raw materials containing from 40 to 60 wt. naphthenic hydrocarbons, for example gas condensates, the effectiveness of the known method is unsatisfactory.

The present invention allows to increase the octane number of the reformate, especially when reforming naphthenic raw materials. The high efficiency of the process is stored by increasing the sulfur content of the feedstock to 20-30 million ^-1.

This result is achieved by the proposed method, in accordance with which the catalytic reforming of gasoline fractions is carried out on a highly sensitive to sulfur platinum-rhenium catalyst at 460-540 ^o C and pressure up to 5 MPa with preliminary adsorption purification of raw materials by passing it with hydrogen through a layer of platinum-containing catalyst and then a layer of manganese oxide adsorbent at 340-460 ^o C, wherein the platinum-catalyst in a zone of clearing layers to locate one of them over a bed of adsorbent, the remaining or layer after layer oksidnomargantsevogo adsorbent.

 Preferably, an additional layer of platinum-containing catalyst is placed in the layer of manganese oxide adsorbent after at least 1/3 of the volume of the latter.

Technically, the proposed method is as follows. The platinum-containing catalyst and the manganese oxide adsorbent are loaded into the purification reactor or reactors in the sequence: the first layer along the raw material (as in example 1 of the known method) is the platinum-containing catalyst, the next layer is the manganese-oxide adsorbent, then the platinum-containing catalyst is an manganese oxide adsorbent. The platinum-containing catalyst can also be loaded after the layer of manganese oxide adsorbent, in which case it is not necessary to load between the layers of the adsorbent. The number of catalyst layers may be more than two, while one of them should always be the first along the cleaned mixture. Preferably, the second platinum-containing catalyst layer is located after at least 1/3 of the volume of the manganese oxide adsorbent. Reforming feed with a circulating hydrogen-containing gas is passed through the treatment zone at a pressure of up to 5 MPa and a temperature normal for purification of 370-460 ^° C. The purified stream in the gas phase is heated in the furnace to a reforming temperature of 460-560 ^° C and is contacted with a sulfur-sensitive catalyst.

 In the cleaning zone, platinum-containing catalysts, which are generally insensitive to sulfur, are used, for example, fluorinated or chlorinated alumina-platinum reforming catalysts, platinum catalysts such as pentasil, beta zeolite, with the addition of alkali or alkaline earth metals, known for their low sensitivity to sulfur [7] Platinum-rhenium catalysts may also be used in which the rhenium content does not exceed the platinum content. In the reforming zone, as a rule, highly effective and sulfur-sensitive catalysts are used, especially platinum-rhenium, in which the rhenium content is higher or equal to the platinum content. The compositions of the catalysts in the purification zone and the reforming zone are not the subject of the invention, a wide range of known catalysts can be used in the claimed method. As oxide manganese adsorbent, as in the known method, use compositions containing over 50 wt. manganese oxide based on MnO (the rest is a binder).

The salient features of the claimed method are:
distribution of a platinum-containing catalyst in the treatment zone in two or more layers;
placing an additional layer of platinum-containing catalyst in the layer or after the layer of manganese oxide adsorbent.

 A preferred feature is the placement of an additional layer of a platinum-containing catalyst after at least 1/3 of the volume of the oxide-manganese adsorbent.

 The absence among the known technical solutions in the field of catalytic reforming of gasoline fractions of the essential distinguishing features of the claimed invention allows us to conclude that the claimed technical solution meets the requirement of novelty.

Using the proposed method can improve the efficiency of reforming processes, and the octane number of catalysis is increased by 165-2 points. These results are achieved even at feed containing a significant amount of sulfur (10-30 mn ^-1) and naphthenes (40-60 wt.). When working on such raw materials, it is possible to eliminate the need to build a preliminary hydrotreating unit on an aluminum-nickel-molybdenum or aluminum-cobalt-molybdenum catalyst and significantly improve the economic performance of the processes. Adsorption purification provides the necessary depth of purification of raw materials for operation on sulfur-sensitive reforming catalysts.

 The obtained effect takes place without increasing the amount of platinum-containing catalyst and manganese oxide adsorbent in the purification zone. The same amount of platinum-containing catalyst must be distributed in two or more layers, placing the underlying catalyst layer in the adsorbent layer, or after it, the efficiency of the reforming process increases.

 This fact indicates the non-obviousness of the proposed technical solution.

 The effectiveness of the method is illustrated by the following examples.

EXAMPLE 1. For the experiment using the gasoline fraction of the Surgut gas condensate with the following characteristics:
Density at 20 ^o C, g / cm ³ 0.739
Fractional composition, ^o C:
start of boil 85
10% 93
50% 101
90% 114
95% 120
end of boil 134
Hydrocarbon composition, wt.

Paraffin 39.4
Naphthenic 54.7
Aromatic 5.9
Sulfur content, ppm ^-1 20
The experiments are carried out on a two-jet installation with the circulation of hydrogen-containing gas reforming. The first reactor serves as an adsorber, where a platinum-containing catalyst and manganese oxide adsorbent are loaded in layers, the second is actually a reforming reactor. Hydrogen-containing feed gas is passed sequentially through an adsorber reactor and a reforming reactor.

Test conditions:
The pressure in the system is 2 MPa, the volumetric transmission rate of the feedstock relative to the total volume of the platinum-containing catalyst and adsorbent in the first reactor is 2.5 h ^-1 , which is relatively highly sensitive to sulfur in the reforming catalyst in the second reactor is 1.5 h ^-1 . The multiplicity of the circulation of hydrogen-containing gas is 1000 vol / vol of raw materials. The temperature at the inlet to the adsorber reactor is 390 ^o C, and to the reforming reactor 485 ^o C. As a low-sensitivity platinum-containing catalyst, the AP-56 catalyst (TU 38.101486-77 from conv. 1) containing 0.55 wt. platinum and 0.35 wt. fluorine on alumina. Designation Pt-F. As the oxide-manganese adsorbent, the adsorbent KAS-50 is used according to TU 21-138-04749189-95. The manganese oxide content of about 70 wt. the rest is a binder. Designation MnO. The ratio of the volumes of the AP-56 catalyst and the KAS-50 adsorbent in the cleaning zone is 1: 3. Half of the PtF volume is loaded in the first upper layer along the feed, the second half of the PtF volume in the middle of the manganese oxide adsorbent layer. The sequence of distribution of the volumes of the layers in the treatment zone is 0.5 PtF 1.5 MnO 0.5 PtF 1.5 MnO. RB-11 (TU 301-03-003-90), highly sensitive to sulfur, is loaded into the reforming zone, containing 0.26 wt. platinum, 0.60% wt., rhenium, 1 wt. chlorine, aluminum oxide the rest. The reforming process is carried out first at a temperature in the second reactor of 510 ^o C for two days, then it is reduced to 480 ^o C and carry out a 10-day run under these conditions. At the end of the run, the yield of stable catalyst is 86.8 wt. and its octane number is 98 points for the study. method. The sulfur content of the liquid product after purification zone 0.09 million ^-1, and the hydrogen sulfide concentration in the recycle gas below the measurement limit (less than 0.1 mg / m ^3).

 EXAMPLE 2. The experiment is carried out under conditions similar to example 1, with the difference that the sequence of distribution of the volumes of the layers in the adsorber reactor along the feedstock is 0.4 PtF 3 MnO 0.6 PtF.

The amount of platinum-containing catalyst and manganese oxide adsorbent is the same as in example 1. The yield of stable catalysis was 86.9 wt. and the octane number is 97.6 points in the study. method. The sulfur content of the liquid product after 0.1 million adsorber less than ^-1, the hydrogen sulfide content in the recycle gas of 064 mg / m ^3.

 The reforming results are similar to those obtained in Example 1, despite the fact that a small amount of hydrogen sulfide is present in the circulating gas.

 EXAMPLE 3. The experiment is carried out under the conditions of example 2 with the only difference that the platinum-containing catalyst, placed after the manganese oxide adsorbent, is a platinum-rhenium catalyst KP-108 (TU 38.101769-85 with reference 4). The content of platinum and rhenium in the catalyst of 0.36 wt. Designation Pt-Re. The yield of stable catalyzate based on raw materials is 86.6 wt. and the octane number is 98.3 points in the study. method. The sulfur content in the purified product and the hydrogen sulfide in the circulating gas is the same as in example 2. This example illustrates the possibility of using a platinum-rhenium catalyst in an additional layer of the purification zone.

EXAMPLE 4 (prototype). The experiment is carried out under the conditions of example 1 with the only difference that as a platinum-containing catalyst in the purification zone, a platinum-tin catalyst containing 0.38 wt. Pt, 0.3 wt. Sn and 1 wt. Ci. Designation Pt-Sn. In addition, the entire catalyst is located in the first layer along the feedstock in front of the layer of 1PtSn - 3MnO manganese oxide adsorbent. The yield of stable catalyzate was 87.1 wt. and the octane number is 96.3 points in the study. method. The sulfur content of the liquid product after 0.4 million adsobrera ^-1, the hydrogen sulfide content in the recycle gas of 0.8 mg / m ^3.

 EXAMPLE 5 (prototype). The experimental conditions are similar to those shown in example 4 with the difference that the Pt-F catalyst is used in the first layer along the feed. The yield of stable catalyzate 86.9 wt. and its octane number is 96.1 points in the study. method. The sulfur content in the purified liquid product and hydrogen sulfide in the circulating gas is the same as in example 4.

EXAMPLE 6. The experiment is carried out analogously to example 1 with the difference that the second layer of the platinum-containing catalyst is placed after 1/3 of the volume of the layer of manganese oxide adsorbent in the sequence: 0.5PtF 1MnO 0.5PtF - 2MnO. The yield of stable catalyzate was 87.2 wt. octane number 97.2 points on the study. method. The sulfur content in the purified liquid product 0.12 million ^-1, hydrogen sulfide in a gas of 0.5 mg / m ^3. The results show that, placing the second layer of Pt-F catalyst earlier than after 1/3 of the adsorbent volume slightly reduces the reforming efficiency, however, in general, the octane number remains higher than in the known method. This implies the preference for placing the second layer of a platinum-containing catalyst after at least 1/3 of the volume of the manganese oxide adsorbent.

 EXAMPLE 7. Test conditions analogous to example 1 with the difference that the Pt-F catalyst in the purification zone is arranged in three layers as follows, 0.5PtF 1.3MnO 0.3PtF 1.2MnO 0.2PtF 0.5MnO. The yield of stable catalyzate 87.0 wt. octane number 98.2 points on the study. method. The sulfur content in the purified product and hydrogen sulfide in the circulating gas are below the sensitivity limits of the analysis.

 An example illustrates the possibility of distributing a platinum-containing catalyst in a treatment zone of more than two layers.

 Examples 1-7 are summarized in a comparative table.

 From the above data it follows that the application of the proposed method (examples 1-3, 6, 7) can increase the octane number of the reformate by 1.5-2 points.

 EXAMPLE 8. The AP-56 catalyst and KAS-50 adsorbent are loaded into the adsorber reactor in the following sequence along the feed: 0.4Ptf 3MnO 0.6PtF. The amount of platinum-containing catalyst and manganese oxide adsorbent is the same as in example 1.

The experiment is carried out at a pressure of 0.7 MPa, a purification temperature of 460 ^o C and a reforming temperature of 460 ^o C, while the yield of stable catalysis was 88.2 wt. and the octane number of 95.5 points in the study. method. The sulfur content in the liquid product after the adsorber and hydrogen sulfide in the circulating gas is below the sensitivity limits of the analysis.

 EXAMPLE 9. The AP-56 catalyst and KAS-50 adsorbent are loaded into the adsorber reactor in the following sequence along the feed, 0.4PtF 3MnO 0.6PtF. The amount of platinum-containing catalyst and manganese oxide adsorbent is the same as in example 1.

The experiment is carried out at a pressure of 2.0 MPa, a purification temperature of 340 ^o C and a reforming temperature of 540 ^o C, while the yield of stable catalysis was 85.2 wt. and the octane number of 99.3 points in the study. method. The sulfur content of the liquid product after 0.7 million adsorber ^1, the hydrogen sulfide content in the recycle gas of 262 mg / m ^3.

 Examples 7 and 8 illustrate the temperature range of reforming and purification, which implement the present invention.

 The data in examples 1-7 are shown in the table.

Claims (2)

1. The method of catalytic reforming of gasoline fractions on a highly sensitive to sulfur platinum-rhenium catalyst at 460 540 ^o With preliminary purification of the feed by passing it with hydrogen sequentially through a platinum-containing catalyst and then a layer of oxide-manganese adsorbent at 340 460 ^o С, characterized in that the platinum-containing catalyst have layers with the placement of one of them above the adsorbent layer, the rest in the layer or after the layer of oxide-manganese adsorbent.  2. The method according to claim 1, characterized in that the platinum-containing catalyst layer is placed in the layer of oxide-manganese adsorbent after at least 1/3 of the volume of the latter.

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