WO2022223332A1

WO2022223332A1 - System and process for the isomerisation of light naphtha

Info

Publication number: WO2022223332A1
Application number: PCT/EP2022/059543
Authority: WO
Inventors: Rainer Albert Rakoczy
Original assignee: Clariant International Ltd
Priority date: 2021-04-21
Filing date: 2022-04-08
Publication date: 2022-10-27
Also published as: DE102021110092A1

Abstract

The invention relates to a light-naphtha isomerisation system, comprising a reactor for carrying out an isomerisation reaction and an auxiliary separator, upstream of the reactor in terms of flow, for separating treatment gas from a reactant fluid flowing in the reactor. The invention also relates to a process for the isomerisation of light naphtha.

Description

Plant and process for light gasoline isomerization

The present invention relates to a light gasoline isomerization plant. The present invention also relates to a process for the isomerization of light gasoline.

Powerful engines require anti-knock fuels. The so-called octane number serves as a measure of the knock resistance of a petrol cut. A distinction is made between the research octane number (RON) and the motor octane number (MON). RON and MON are determined on standardized test engines in accordance with local fuel specifications and standards as described in DIN EN ISO 5164. There are also calculation models that use the chemical composition of the fuel as a basis for calculating the RON. Knock resistance can be achieved, for example, by increasing the proportion of alicyclic and branched aliphatic hydrocarbons by adding alkylate petrol or isomerate petrol.

For the isomerization of light gasoline, i.e. C5 and C6 hydrocarbons, to increase knock resistance, there are currently four main technologies available, which are principally determined by the choice of catalyst. In the very outdated high-temperature isomerization, the reaction takes place at temperatures above 350 °C and almost ambient pressure over simple aluminum oxide catalysts. In high-temperature isomerization (HYSOMER process technology), the reaction takes place at temperatures between 250 °C and 300 °C at pressures of around 20 bar over platinum-containing zeolite catalysts such as HS-10 from UOP, HYSOPAR ^® from Clariant or other comparable commercially available catalysts. In medium-temperature isomerization, the reaction takes place at temperatures between 180 °C and 200 °C at pressures of around 20 bar over platinum-containing mixed oxide catalysts such as IP-100 from UOP (Parlsom™ process technology) or SI-2 from JSC Nefthechim (IsoMalk™ process technology). In low-temperature isomerization, the reaction takes place at temperatures between 80 °C and 180 °C at pressures of around 20 bar over platinum-containing aluminum chloride catalysts such as I-85 from UOP (PENEX ^® process technology) or ATIS-2L from Axens.

The isomerization of light petroleum is an equilibrium reaction in which the equilibrium position favored for iso-paraffins can be reached at low temperatures. As a result, process technologies for low- and medium-temperature isomerization are far more widespread than process technologies for high-temperature isomerization. However, the catalysts for the high-temperature isomerization are characterized by a significantly higher robustness and tolerance, for example, to moisture flowing into the insert. In addition, this technology is used in plant conversions from existing ones aggregates used. Due to the unfavorable equilibrium situation, process variants are offered for high-temperature isomerization in which the result in terms of knock resistance is optimized through a wide variety of separation processes and recycling of the normal paraffins.

One process variant is the total isomerization package (TIP), in which a combination of isomerization in a HYSOMER reactor and separation of iso- and normal paraffins by adsorption on molecular sieves in a so-called ISOSIV module is selected. This combination makes it possible to maximize the proportion of high RON iso-paraffins in the feedstock stream and to maximize the proportion of low RON normal paraffins in the isomerization feedstock stream. In the case of TIP systems, there are again two versions, namely with an upstream or downstream ISOSIV module. Due to the process, the effluent of the normal paraffins from the ISOSIV module is very rich in hydrogen because the adsorbed normal paraffins are desorbed with the aid of a very high flow of hydrogen. Particularly in the embodiment with an upstream ISOSIV module, this leads to a very high hydrogen concentration in the reaction fluid at the inlet of the HYSOMER reactor, which ultimately leads to unfavorable operation.

Isomerization on bifunctional catalysts, such as in the HYSOMER reactor, always takes place in the presence of hydrogen, which is usually circulated in a significant stoichiometric excess at operating pressures of 10 to 30 bar overpressure. In the isomerization over zeolite-based catalysts, molar cycle hydrogen flow-to-feed hydrocarbon flow ratios (MHOV) of about 1.2 to 2.0 allow, which corresponds to a cycle hydrogen-to-feed hydrocarbon volume flow ratio (VHOV) of about 250 Nm ³ /m ³ corresponds, the best results in increasing the RON. An increase in the MHOV or VHOV leads to a strong dilution of the reaction mixture and thus to a massive reduction in the contact probability and contact time on the active catalyst surface. This phenomenon has a direct negative effect on the isomerization activity. In addition, high hydrogen partial pressure adversely affects the rate constant for isomerization of paraffins. In many cases, the MHOV of the normal paraffin stream from the ISOSIV unit is significantly greater than 15.

However, both the HYSOMER reactor and the ISOSIV module are in the same cycle hydrogen stream, also called the cycle treat gas stream. In the case of known TIP plants, it is therefore not possible to reduce the circulating treatment gas stream upstream of the HYSOMER reactor in such a way that optimum isomerization activity can be achieved in the HYSOMER reactor. In addition, many light gasoline isomerizations are also constrained to achieve optimal cycle treat gas flow due to the cycle treat gas compressor selected or available. As a result, the HYSOMER reactor in TIP plants is often operated at an excessively high cycle treatment gas flow to feed oil flow ratio. Even with catalysts with excellent C5/C6 isomerization activity, such as Clariant's HYSOPAR ^® -5000, only a slight increase in knock resistance (RON) is possible via the HYSOMER reactor.

If high-temperature isomerization systems are built from existing units, the flow rate of the circulation compressor is often too high for efficient reaction control in the isomerization reactor and the MHOV is too high by a factor of three to five.

The object of the present invention is therefore to make it possible to increase the octane number or knock resistance (RON) at the outlet of the reactor during light gasoline isomerization by targeted reduction of the MHOV.

This object is achieved by a light gasoline isomerization plant, which has the features according to claim 1, and by a method for light gasoline isomerization, which has the features according to claim 12.

The auxiliary separator for the partial separation of the treatment gas is upstream of the reactor for carrying out an isomerization reaction based on the gas flow through the plant. The auxiliary separator may be located downstream of the reactor and a feed oil inlet of the plant.

The present invention enables optimal adjustment of the recycle treatment gas flow to hydrocarbon flow ratio (VHOV, MHOV) in favor by using a partial recycle treatment gas/hydrocarbon separation before the isomerization reactor, which can be for example a HYSOMER reactor the overall increase in knock resistance (RON) over the reactor. The overall octane yield can preferably be increased by a factor of 3.5 with the procedural measure according to the invention.

The basis for the depletion of the proportion of the treatment gas in the reactant fluid is preferably the establishment of a phase equilibrium. This allows the paraffinic oil to be separated from the hydrogen and light components (methane, ethane, propane and partly butanes), allowing the paraffinic oil to pass into the liquid phase. Structurally, the auxiliary separator used for this consists preferably of a device for adjusting the temperature, such as air coolers or heat exchangers, followed by a device for gas-liquid separation, such as phase separators, condensers or distillation columns. The separation of the treatment gas from the reaction fluid via different permeation at a membrane is also possible. The auxiliary separator for separating recycle treatment gas from a reactant fluid flowing into the reactor may have one or more components selected from a membrane, a product separation column and include a high-pressure separator. In a preferred embodiment, the auxiliary separator comprises a high-pressure separator.

The auxiliary separator is preferably set up to lower the MHOV of the reactant fluid to about 1.2 to 2.0 before it is introduced into the isomerization reactor. Preferably, the auxiliary separator is configured to lower the MHOV of the reactant fluid from about 15 to 25 to about 1.2 to 2.0 prior to introduction into the isomerization reactor.

In light petroleum isomerization, the starting oil is isomerized as paraffinic oil either directly or by separating isomerate oil, since dilution with hydrogen is necessary regardless of the pre-separation. This hydrogen is preferably circulated using a compressor. Due to side reactions such as cracking and hydrogenation reactions, hydrogen is sometimes consumed and contaminated with low-molecular hydrocarbons (methane, ethane, propane) and/or hydrogen sulfide, with the proportion of hydrogen being well over 60 percent by volume. The cycle hydrogen is called treatment gas or cycle treatment gas. The mixture of paraffinate oil and treat gas, or the mixture of feed oil and treat gas if no prior separation of isomerate oil occurs, is called the reactant fluid. The gas stream flowing or directed into the reactor to carry out the isomerization reaction is the reactant fluid. The fluid after leaving the isomerization reactor is called reaction effluent or product oil and finally, after separation of the treat gas, isomerization product oil.

The reactor for carrying out the isomerization reaction can comprise one or more batch reactors with axial flow. The reactor can comprise several batch reactors, with at least one of the reactors being flown through axially and the remaining reactors being flown through radially. The reactor can comprise several set reactors, with at least one of the reactors being flowed through radially and the remaining reactors being flown through axially. The reactor may comprise a membrane reactor. The reactor can include a reactive distillation.

The reactor may comprise a HYSOMER reactor. The HYSOMER reactor preferably represents the realization of a flow tube. The reactor can include internals that are customary in process engineering in order to accommodate a solid catalyst and/or to achieve an almost ideal flow around the catalysts. The reactor is preferably divided into two beds with intermediate cooling in order to mitigate any exotherms that occur due to hydrogenation reactions taking place in parallel. Intermediate cooling can be achieved by feeding in cold treatment gas or fresh hydrogen.

The light gasoline isomerization plant may include a device for the concentration and depletion of normal paraffins. Preferably, the auxiliary separator is between the device for concentrating and depleting normal paraffins and the reactor in terms of flow switched. The device for the concentration and depletion of normal paraffins is preferably designed upstream of the reactor for carrying out the isomerization reaction.

Normal paraffins can be concentrated or depleted by distillation. The device for enriching and depleting normal paraffins can be designed as a device for distillation. The device for enriching and depleting normal paraffins in the hydrocarbon stream can comprise a battery of distillation columns.

Normal paraffins can be enriched or depleted by permeation through a membrane. The device for the concentration and depletion of normal paraffins can include a membrane for carrying out a permeation process. The device for the concentration and depletion of normal paraffins can comprise an arrangement of membranes for carrying out a permeation process. The device for concentrating and depleting normal paraffins can use an adsorption process. The device for the concentration and depletion of normal paraffins can include an ISOSIV module.

The ISOSIV module is preferably an arrangement of three parallel flow tubes. These flow tubes can be filled with a zeolite-based molecular sieve (e.g. Adsorbent N-10 from UOP). During operation, the molecular sieve can be charged in the gas phase with a hydrocarbon mixture to be separated, consisting of normal paraffins, iso-paraffins, alicyclics and aromatics, such as the starting oil. The application is usually only with hydrocarbons without other carrier gases such as hydrogen, nitrogen or helium. Due to the molecular sieve effect, the normal paraffins can be adsorbed on the inner surfaces of the adsorbent. The other components can pass through the flow tube without any interaction and exit the ISOSIV module as isomerate oil or raffinate. After a certain time, the molecular sieve reaches the adsorption capacity for normal paraffins. In order to prevent these species from breaking through into the isomeric oil, it is possible to switch to one of the flow tubes arranged in parallel, which contains an unloaded molecular sieve. For desorption from the sieves, the normal paraffins can be eluted using a very high recycle treat gas flow and the entire mixture fed as reactant fluid to the HYSOMER reactor for hydroisomerization.

The light gasoline isomerization unit may include one or more pumps for conveying the feed oil stream.

The light gasoline isomerization unit may include one or more compressors for conveying the treat gas stream. The light gasoline isomerization unit may include a cycle treat gas compressor located upstream of the normal paraffin concentrator. The light gasoline isomerization unit may include a compressor located downstream between the auxiliary separator and the reactor. The light gasoline isomerization unit may include one or more heat exchangers and/or one or more furnaces. Heat exchangers and/or furnaces may be used at various locations in the plant and may be used to regulate the temperature of various streams, for example feed, intermediate, product and/or treat gas streams. A heat exchanger is preferably connected directly upstream of the auxiliary separator and/or a heat exchanger is connected directly downstream of it.

The light gasoline isomerization system may include one or more components selected from valves, throttles, orifices, flaps and back pressure regulators. These can be used at different points in the plant and can be used to control flow rates and pressures of various streams, for example feed, intermediate, product and/or treat gas streams.

The light gasoline isomerization plant can include one or more further separation devices for adjusting boiling ranges, densities, or separating or stabilizing products.

The light gasoline isomerization unit may include treat gas bypass between the normal paraffins concentrator and the reactor for carrying out the isomerization reaction. The treatment gas bypass can be designed to introduce the treatment gas partially and in a controlled manner at the point at which the isomerization reaction takes place.

In some embodiments, the light gasoline isomerization plant is configured to at least partially reintroduce cycle treatment gas separated by the auxiliary separator into the plant cycle downstream of the reactor.

In a preferred embodiment, part or all of the separated portion of the cycle treatment gas is fed back into the system cycle immediately before the cycle treatment gas compressor in order to achieve the necessary operating conditions for the ISO-SIV MODULE.

The light gasoline isomerization unit may include, in addition to the auxiliary separator, a main separator for separating the treat gas from the reaction effluent. The main separator is installed downstream of the reactor to carry out the isomerization reaction. The main separator is preferably a high-pressure separator. The main separator is preferably provided as a separate component to the auxiliary separator. The main separator is particularly preferably arranged downstream of the reactor and the auxiliary separator is arranged upstream of the reactor.

The light gasoline isomerization plant may be a plant for conducting the high-temperature isomerization process. The light gasoline isomerization unit may be a TIP (Total Isomerization Package) unit. In one embodiment, the light gasoline isomerization plant comprises an ISOSIV module and a HYSOMER reactor, with the auxiliary separator being connected in flow between the ISOSIV module and the HYSOMER reactor. In one embodiment, the light gasoline isomerization plant comprises an ISOSIV module, a HYSOMER reactor and a main separator, with the auxiliary separator being downstream between the ISOSIV module and the HYSOMER reactor, and with the main separator being downstream of the HYSOMER reactor. The light gasoline isomerization unit may include a cycle treat gas compressor located upstream of the ISO SIV module.

The system can include a gas bypass with a three-way metering valve in order to optionally feed at least parts of the treatment gas stream separated by means of the auxiliary separator back to the reactant fluid between the auxiliary separator and the reactor and/or to direct it via a non-return valve directly to the suction side of the cycle treatment gas compressor.

The system can include a gas bypass with a three-way metering valve in order to optionally feed at least parts of the treatment gas flow separated with the aid of the auxiliary separator back to the reactant fluid between the auxiliary separator and the reactor and/or to direct it via a non-return valve to the inlet of the main separator.

The system can include a gas bypass with a three-way metering valve in order to optionally feed at least parts of the treatment gas stream separated with the aid of the auxiliary separator between the auxiliary separator and the reactor back into the reactant fluid via an auxiliary compressor and/or direct it via a check valve to the inlet of the main separator.

The system can include a gas bypass with a three-way metering valve in order to optionally feed at least parts of the treatment gas flow separated with the aid of the auxiliary separator back into the reactant fluid between the auxiliary separator and the reactor and/or direct it via a non-return valve to the outlet of the HYSOMER reactor.

The present invention also relates to a process for the isomerization of light gasoline. For the purposes of the present invention, light petrol is understood by the person skilled in the art to be a mixture of C5-C6 hydrocarbons, ie hydrocarbons having at least 5 carbon atoms or at most 6 carbon atoms. Mineral spirits typically have an initial boiling point of at least 20°C and a final boiling point of no more than 95°C, as measured by ASTM D86. The light gasoline entering the light gasoline isomerization plant can contain impurities and by-products in addition to the hydrocarbons to be isomerized. The sulfur content is up to 10000 ppm, preferably up to 5000 ppm, particularly preferably up to 1000 ppm, more preferably from 50 to 1000 ppm. In one embodiment, the sulfur content is in the range from 100 to 10,000 ppm, preferably im Range from 500 to 5000 ppm, more preferably in the range from 500 to 1000 ppm. The proportion of nitrogen in the hydrocarbon mixture is usually in the range from 1 to 100 ppm, preferably in the range from 5 to 10 ppm. The proportion of C4 hydrocarbons is usually in the range from 0.5 to 4% by mass. The proportion of benzene in the hydrocarbon mixture is usually up to 7% by mass, in particular up to 5% by mass, and is preferably in the range from 1 to 5% by mass. The proportion of C7+ hydrocarbons, ie hydrocarbons having at least 7 carbon atoms, is usually up to 7% by mass, preferably up to 4% by mass and is particularly preferably in the range from 0.5 to 4% by mass. The method includes providing a light gasoline isomerization unit as described herein. The method further includes separating treat gas from a reactant fluid flowing into the reactor using the auxiliary separator and introducing the treat gas-depleted reactant fluid into the reactor. Preferably, the process further comprises isomerizing reactant fluid in the reactor.

Unless otherwise stated, features that are described in connection with individual embodiments can also be used in connection with other embodiments.

Exemplary embodiments of the invention are explained below with reference to the drawing. Show it:

1 process flow diagram of a previously known light gasoline isomerization system of the TIP type;

2 process flow diagram of an exemplary embodiment of a light gasoline isomerization plant;

3 shows a process flow diagram of an exemplary embodiment of a further light petroleum isomerization plant;

4 shows a process flow diagram of an exemplary embodiment of a further light petroleum isomerization plant; and

Fig. 5 process flow diagram of an embodiment of another light gasoline isomerization plant.

1 shows a simplified system flow diagram for describing a conventional prior art TIP system. The input oil stream 10 reaches the ISOSIV module 12 by mechanical cal conveyance by means of an input oil pump and the normal paraffins are primarily adsorbed on the surface of micropores of a molecular sieve bed in an adsorber tower that is in adsorption mode. Most of the iso-paraffins and alicyclic hydrocarbons of feed oil stream 10 bypass the micropores due to the molecular sieve effect. This isomeric oil stream passing through the micropores 14 leaves the adsorber tower and is fed directly to the inlet of a stabilization column 16 .

After reaching a certain level of saturation, the corresponding adsorber tower is switched to desorption operation. For desorption, the circuit treatment gas stream 18, which has been brought to the required desorption temperature using heat exchangers or furnaces, is conducted to the adsorber tower. The circulatory treatment gas stream, enriched in this way with primarily normal paraffins, is fed as a paraffinate oil stream 20 directly into a HYSOMER reactor 24 for catalytic conversion after temperature adjustment with heat exchangers 22a. The paraffinic oil stream 20 is the reactant fluid. The reaction effluent is the HYSOMER product oil stream 26. After temperature adjustment, the HYSOMER product oil stream 26 is passed through a heat exchanger 22b to separate the circulating treatment gas stream or the treatment gas via a main separator in the form of a high-pressure separator 28a. The HYSOMER product oil stream 26 is then combined with the isomerate oil stream 14 and converted into stable products 34, 36, 38 by suitable distillation in the stabilization column 16.

The total pressure of the circuit treatment gas stream 18 separated by means of the high-pressure separator 28a is reduced by a valve device 29 . This serves to deplete the lower hydrocarbons (C1 to C3, little C4) from cracking reactions and thus to lower the density of the circuit treatment gas stream 18.

A circuit treatment gas compressor 30a is used to achieve the necessary system pressure and the necessary flow rate of the circuit treatment gas stream 18.

FIGS. 2 to 5 show different embodiments of plants according to the invention in the form of flow charts. In all examples of FIGS. 2 to 5, the input oil flow 10 reaches the ISOSIV module 12 as in FIG. 1 by mechanical conveyance, for example using an input oil pump . The isomerate oil stream 14 is fed directly to the inlet of a stabilization column 16 as in FIG. In contrast to the embodiment of FIG. 1, the paraffin oil stream 20 enriched by desorption from the adsorber tower with primarily normal paraffins is conducted in the inventive embodiments of FIGS. 2 to 5 after temperature adjustment with heat exchangers 22a into a small auxiliary separator 28b. In the exemplary embodiments of FIGS. 2 to 5, the auxiliary separator 28b is designed as a high-pressure separator or high-pressure separator. With the aid of the auxiliary separator 28b, parts of the treatment gas contained in the paraffinate oil stream 20 are partially or completely separated from it. The circuit treatment gas stream separated by the auxiliary separator 28b is divided by a three-way metering valve 42 or a three-way back pressure regulator. The one Part is fed to the paraffinic oil stream 20 and, after temperature adjustment with heat exchangers 22c, is fed directly into the HYSOMER reactor 24 for catalytic conversion. The other part 40 is passed directly via a non-return valve 44 to the inlet of the Circulation treatment gas compressor 30a. The three-way metering valve 42 is adjusted in such a way that a maximum increase in the conversion of the paraffinate oil 20 via the HYSOMER reactor 24 is achieved. After the temperature has been adjusted, the HYSOMER product oil stream 26 is passed through a heat exchanger 22b to separate the remaining circuit treatment gas stream from the HYSOMER product oil stream 26 via a high-pressure separator 28a. The HYSOMER product oil stream 26 is then combined with the isomerate oil stream 14 and converted into stable products 34, 36, 38 by suitable distillation in the stabilization column 16.

The circulatory treatment gas flow 18 separated off at the high-pressure separator 28a is finally reduced by a valve device 29, as in the embodiment of FIG. 1, also in the embodiments of FIGS. Likewise, a cycle treatment gas compressor 30a is also used in FIGS. 2 to 5, at the inlet of which the depleted treatment gas flow 18 is mixed with fresh gas 32 and the previously separated treatment gas flow 18 and the output flow 18 of which is routed to the ISOSIV module 12.

The exemplary embodiment in Fig. 2 includes a gas bypass with a three-way metering valve 42 in order to feed at least parts of the treatment gas stream separated with the aid of the auxiliary separator 28b between the auxiliary separator 28b and the reactor 24 back into the reactant fluid and/or via the check valve 44 directly to the suction side of the cycle treatment gas compressor 30a.

In contrast to the embodiment of FIG. 2, in the embodiment of FIG. 3 the diverting of the separated portions of the treatment gas stream 40 is routed directly to the inlet of the first high-pressure separator 28a.

In the exemplary embodiment in FIG. 4 , the separated parts of the treatment gas stream 40 are also diverted directly to the inlet of the first high-pressure separator 28a. In contrast to the embodiment of FIG. 3, however, an additional auxiliary compressor 30b is used.

In the exemplary embodiment of FIG. 5, the diverting of the separated portions of the treatment gas stream 40 is routed directly to the outlet of the HYSOMER reactor 24.

With the procedural measure according to the invention, the separation capacity of the ISOSIV module 12 is not changed in the examples mentioned in FIGS. The device can thus be easily realized with commercially available components such as heat exchangers, valves, back-pressure regulators, non-return valves, auxiliary feed pumps and auxiliary compressors. In general, the anti-knock properties of the input and outlet oil flows of the corresponding units are used to assess such TIP systems. A fictitious but realistic feed oil composition 10 and fictitious but realistic compositions of paraffinic oil 20 and isomeric oil 14 from an ISOSIV module operation defined as optimized serve as the basis for calculating the impact of the structural change that is part of this invention.

Theoretical research octane numbers (TRON) can be calculated according to equation (1) below by linearly combining n components of the RON and volume fraction v of the individual component i:

TROZ = S?ni RONi (1 )

The RON of the individual components are listed in "Technical Data Book - Petroleum Refining", 6th edition, API, Washington D.C., USA, April 1997, pages 1-89 to 1-121.

Since the calculation often also requires the densities of the corresponding hydrocarbon mixtures, theoretical normal densities (TSG) were calculated according to equation (2) below by linearly combining n components of the SG and mass fraction x of the individual component i:

TSG = SG i SGi (2)

Mass and volume fractions are usually determined by standardized capillary gas chromatography methods.

The adaptation of the circuit treatment gas flow is helpful in each case upstream of the two parts of the plant, the ISOSIV module 12 and the HYSOMER reactor 24, in order to achieve even greater increases in the knock resistance of the product gasoline.

The mean catalyst bed temperature (WABT) in the isomerization in the presence of hydrogen is calculated using equation (3) below:

WABT — ^T ENTRY+ ^{2 'T} AU STRITT ^

If the HYSOMER reactor 24 is operated with an optimized average WABT and with very high treatment gas stream flow rates, as described for example in the comparative example below, the equilibrium achieved in this way for the conversion of the paraffin oil allows the theoretical knock resistance to be increased by only 6 .9 units. The treatment gas stream flow rates used are about a factor of ten higher than the treatment gas stream flow rates, which lead to an optimal setting of the isomerization equilibrium.

The ratio of the isopentane mass fraction Xi _Pn to the sum of the isopentane mass fraction Xi _Pn and the normal pentane Mass fraction c _prp in the HYSOMER product oil. This ratio, as described in equation (4), is also called isopentane activity.

Even when using feed oils that can be easily converted and highly active catalysts such as Clariant's HYSOPAR® 5000, isopentane activities of at most 0.52 can be achieved at such high treatment gas flow rates due to the massive dilution of the reaction fluid.

The separation and preferably partial diversion of the treatment gas stream according to the invention allows the circulating hydrogen to feed hydrocarbon volume flow ratio to be reduced upstream of the HYSOMER reactor 24 to such an extent that the isomerization equilibrium can be established. As a result, typical isopentane activities of 0.65 can be achieved in the example according to the invention described below. With the converted fictitious paraffinic oil, an increase in the theoretical knock resistance of almost 24 units is achieved by conversion under these improved conditions.

EXAMPLES

DESCRIPTION OF THE C4+ CURRENT FOR THE EXAMPLES USE OIL

Table 1 describes the typical composition and some material properties of a typical starting oil (stream 10 according to the figures) for a light gasoline isomerization plant after separating off the volatile (<−12° C.) components (C4+ cut). Table 1: Typical composition and some material properties of a typical feed oil for a light gasoline isomerization plant after separation of the volatile (<-12°C) components (C4 ₊ cut).

PARAFFINATOL

Table 2 describes the typical composition and some material properties of the C4+ cut of a paraffinate oil obtained by applying an ISOSIV module 12 to an input oil (light petrol) as described in Table 1 (stream 20 according to the figures).

Table 2: Typical composition and some material properties of a PARAFFINATE OIL from an ISOSIV MODULE after separation of the volatile (<-12°C) components (C4 ₊ cut)

ISOMERATOL

Table 3 describes the typical composition and some material properties of the C4+ cut of an isomerate oil obtained by applying an ISOSIV module 12 to an input oil (light petrol) as described in Table 1 (stream 14 according to the figures). Table 3: Typical composition and some material properties of a

Isomer oil from an ISOSIV module according to Comparative Example 4 and Example 2 after separating off the volatile (<−12° C.) components (C ₄₊ cut).

COMPARATIVE EXAMPLE

The comparative example describes the isomerization equilibrium optimized for an ISOSIV MODULE.

By optimizing the operation of the ISOSIV module 12, i.e. with a very high hydrogen mass flow, the subsequent HYSOMER reactor 24 is operated using a commercially available HYSOPAR® 5000 catalyst with the following conditions:

WABT: 250°C

Working pressure: 18 barg LHSV: 1.2 l/h

^VHOV : 3100 ^Nm3 /m3

MHOV: 15 mol/mol

In the reaction, a mass-related yield for the C4+ cut from the HYSOMER product oil (stream 26 according to the figures) of 99.30% by mass is achieved, the composition and some selected properties of which are summarized in Table 4. The conversion via the HYSOMER reactor achieves an absolute increase in the theoretical knock resistance TROZ by only 6.7 units. Table 4: Typical composition and some material properties of the

HYSOMER PRODUCT OIL obtained according to the comparative example by reacting PARAFFINATE OIL, as described in Table 2, after separating off the volatile (<-12°C) components (C4 ₊ cut).

After the treatment gas has been separated off, the HYSOMER product oil (stream 26 according to the figures) is mixed with the isomerate oil stream (stream 14 according to the figures) and distilled again. The composition and some selected properties of the product gasoline obtained (stream 36 according to the figures) are summarized in Table 5. An absolute increase in the theoretical knock resistance TROZ by only 2.5 units is achieved across the entire system.

Table 5: Typical composition and some material properties of the product gasoline after separation of the volatile (<-12°C) components (C4 ₊ cut)

EXAMPLE

The example describes the isomerization equilibrium optimized according to the invention for the HYSOMER reactor. By optimizing the mode of operation of the ISOSIV module 12, i.e. with a very high hydrogen mass flow, and applying the structural change as described in Fig. 2, the subsequent HYSOMER reactor 24 can be operated using a commercially available HYSOPAR® 5000 catalyst with the following optimized conditions ( especially VHOV or MHOV) are operated: WABT: 250°C

Working pressure: 18 barg LHSV: 1.2 l/h

^VHOV : 250 ^Nm3 /m3

MHOV: 1.2 mol/mol In the reaction, a mass-related yield for the C4+ cut at the outlet of the HYSOMER reactor 24 (stream 26 according to the figures) of 97.00% by mass is reached, its composition and some selected properties are summarized in Table 6. The conversion via the HYSOMER reactor 24 achieves an absolute increase in the theoretical knock resistance TROZ by 23.4 units.

Table 6: Typical composition and some material properties of the

HYSOMER product oil obtained by reacting paraffinate oil according to the example according to the invention, as described in Table 2, after separating off the volatile (<-12° C.) components (C4 ₊ cut).

After the treatment gas has been separated off, the HYSOMER product oil (stream 26 according to the figures) is mixed with the isomerate oil stream (stream 14 according to the figures) and distilled again. Composition and some selected properties of the product gasoline obtained (stream 36 according to the figures) are summarized in Table 7. An absolute increase in the theoretical knock resistance TROZ by 8.8 units is achieved across the entire system.

Table 7: Typical composition and some material properties of the product gasoline after separation of the volatile (<-12°C) components (C4 ₊ cut)

The above statements only serve to illustrate the present invention and are not to be interpreted as limiting. Of course, a person skilled in the art will also combine individual or all features that are described in connection with individual embodiments with other embodiments of the present invention. Acronyms, symbols and unit symbols used:

TIP Total Isomerization Package

DIP De-Iso Pentanizer

DIH De-Iso Hexanizer

RON Research octane number

MON engine octane number

TROZ theoretical research octane number

TSG theoretical standard density

Vi volume fraction of component i

Xi mass fraction of component i

EtOHethanol

MTBE methyl tertiary butyl ether nBn normal butane iBn isobutane n-Pn normal pentane m-Pr 2-methylpropane (neo-pentane)

CPn cyclopentane nHx normal hexane

2.2-DMeBn 2.2-dimethyl butane

2.3-DMeBn 2.3-dimethyl butane

2-MePn 2-methylpentane

3-MePn 3-methylpentane CHx cyclohexane MeCPn methyl-cyclopentane nHp+ normal-paraffins higher normal-hexane iHp+ iso-paraffins/cyclo-paraffins with more than six carbon atoms

E.g. benzene

Tol+ aromatic molecules with molecular masses > toluene

S sum sign

C _ö activity Measure for determining the setting of the isomerization equilibrium List of References

Input oil flow 10 ISOSIV module 12

Isomerate oil stream 14

stabilization column 16

Recycle treatment gas stream 18

Paraffinate oil stream 20 heat exchangers 22a, 22b, 22c

HYSOMER reactor 24

HYSOMER product oil stream 26

high pressure separator 28a, 28b

Valve device 29 cycle treatment gas compressor 30a, 30b

fresh gas 32

Products 34, 36, 38 separated treatment gas flow 40 three-way metering valve 42 non-return valve 44

Claims

EXPECTATIONS

1 . Light gasoline isomerization plant comprising a reactor for conducting an isomerization reaction; and an auxiliary separator upstream of the reactor for separating treat gas from a reactant fluid flowing into the reactor.

2. Light gasoline isomerization plant according to claim 1, comprising a device for enriching and depleting normal paraffins, wherein the auxiliary separator is connected in terms of flow between the device for enriching and depleting normal paraffins and the reactor.

3. Light gasoline isomerization plant according to claim 2, wherein the device for enriching and depleting normal paraffins is designed as a distillation device.

4. Light gasoline isomerization plant according to claim 2, wherein the device for enriching and depleting normal paraffins comprises a membrane for carrying out a permeation process.

5. Light gasoline isomerization plant according to claim 2, wherein the device for the concentration and depletion of normal paraffins uses an adsorption process.

6. Light gasoline isomerization plant according to claim 5, wherein the device for the concentration and depletion of normal paraffins comprises an ISOSIV module.

7. Light gasoline isomerization plant according to any one of the preceding claims, wherein the plant is a plant for carrying out the high temperature isomerization process.

8. Light gasoline isomerization plant according to the preceding claims 1, 2 and 6, wherein the plant is a TIP plant (Total Isomerization Package).

9. Light gasoline isomerization plant according to one of the preceding claims, wherein the plant is set up to feed treatment gas which has been separated off by means of the auxiliary separator back into the plant circuit downstream of the reactor.

10. Light gasoline isomerization plant according to any one of claims 1 to 9, wherein the isomerization reactor is designed as a unit for reactive distillation.

11 . Light gasoline isomerization plant according to one of claims 1 to 9, wherein the isomerization reactor is designed as a membrane reactor.

12. A process for the isomerization of light gasoline, comprising: a) providing a light gasoline isomerization plant according to any one of claims 1 to 11; b) separating treat gas from a reactant fluid flowing into the reactor by means of the auxiliary separator; c) introducing the treat gas-depleted reactant fluid into the reactor; and d) isomerizing the reactant fluid in the reactor.

13. The method of claim 12, wherein between step a) and step b) there is a separation of isomeric oil from the reactant fluid.

14. The process of claim 13 wherein the reactant fluid prior to separation of the isomerate oil contains iso- and normal paraffins.