WO2011015662A2

WO2011015662A2 - Method for revamping an hf or sulphuric acid alkylation unit

Info

Publication number: WO2011015662A2
Application number: PCT/EP2010/061513
Authority: WO
Inventors: Zhichang Liu; Chunming Xu; Rui Zhang; Xianghai Meng; Ana Cecilia Patroni; Peter Anton August Klusener; Albertus Vincentius Petrus Van Den Bosch
Original assignee: Shell Internationale Research Maatschappij B.V.; China University Of Petroleum
Priority date: 2009-08-06
Filing date: 2010-08-06
Publication date: 2011-02-10
Also published as: WO2011015662A3

Abstract

The present invention provides a method for revamping an HF or sulphuric acid alkylation unit to an ionic liquid alkylation unit, wherein the HF or sulphuric acid alkylation unit comprises at least: - a reactor unit for contacting catalyst and hydrocarbon reactants; - a separator unit for separating a reactor effluent into a catalyst phase and an alkylate-comprising hydrocarbon phase; - a fractionator unit for fractionating the alkylate-comprising hydrocarbon phase into at least one stream comprising alkylate; and which method includes one or more of : i) providing a means for recycling at least part of the reactor effluent to the reactor unit; ii) providing a means for recycling at least part of the alkylate-comprising hydrocarbon phase to the reactor unit; and/or iii) replacing the reactor unit by a loop reactor. The invention further provides 3 further methods for revamping an HF or sulphuric acid alkylation unit.

Description

METHOD FOR REVAMPING AN HF OR SULPHURIC ACID ALKYLATION

UNIT

The present invention provides a method for

revamping an HF or sulphuric acid alkylation unit.

There is an increasing demand for alkylate fuel blending feedstock. As a fuel-bending component alkylate combines a low vapour pressure, no olefin or aromatic content with high octane properties.

Almost all alkylate is produced by reacting

isobutane with butene in the presence of a suitable acidic catalyst. The most used catalysts are HF

(hydrofluoric acid) and sulphuric acid. Although well established, these processes suffer numerous

disadvantages. In case of HF, stringent health and safety measures must be applied requiring significant

investments. In case of sulphuric acid, the large

consumption of catalyst and the need to provide utilities for refrigeration are unfavourable from an economic standpoint .

Recently, the alkylation of isoparaffins with olefins using an ionic liquid catalyst has attracted attention as an alternative to HF and sulphuric acid catalysed alkylation processes.

In for instance US7285698 a process for

manufacturing an alkylate oil is disclosed, which uses a composite ionic liquid catalyst to react isobutane with a butene. In the process of US7285698, isobutane and butene are supplied to a reactor unit and the alkylate is formed by contacting the reactants with a composite ionic liquid under alkylation conditions. The reactor effluent is separated into a hydrocarbon phase and an ionic liquid phase. The ionic liquid phase is recycled to the reactor unit while the hydrocarbon phase is treated to retrieve the alkylate.

Current alkylation units have been specifically designed for either HF or sulphuric acid (also referred to as SA) catalyst and are not optimally suited for use of a different catalyst such as an ionic liquid (also referred to as IL) catalyst. In for instance Liu et al . (Z.Liu, R.Zhang, CXu, R.Xia, Ionic liquid alkylation process produces high-quality gasoline, Oil and Gas

Journal, vol 104, Issue 40, 2006) it is mentioned that it is possible to retrofit a sulphuric acid alkylation unit for use of an IL catalyst. In Liu et al . , it proposed to add a surge tank for IL recycle and to modify the settler internals to enhance separation of the IL. However, it was found by Liu et al . that the performance of the retrofitted alkylation unit was less than optimal.

Therefore, there is a need in the art for an

improved method for revamping HF or SA alkylation unit to an IL alkylation unit.

It has been found that the performance of an HF or SA alkylation unit, which was revamped for use as an IL alkylation unit may be improved by modifying the existing alkylation unit.

Accordingly, the present invention provides a first method for revamping an HF or sulphuric acid alkylation unit to an ionic liquid alkylation unit, wherein the HF or sulphuric acid alkylation unit comprises at least: a reactor unit for contacting catalyst and hydrocarbon reactants;

a separator unit for separating a reactor effluent into a catalyst phase and an alkylate-comprising hydrocarbon phase; a fractionator unit for fractionating the alkylate- comprising hydrocarbon phase into at least one stream comprising alkylate; and

which method includes one or more of:

i) providing a means for recycling at least part of the reactor effluent to the reactor unit; ii) providing a means for recycling at least part of the alkylate-comprising hydrocarbon phase to the reactor unit; and/or

iii) replacing the reactor unit by a loop reactor.

The present invention relates to a first method for revamping an HF or SA alkylation unit to an IL alkylation unit. Reference herein to revamping is to modifying or adapting an existing unit or process line-up designed for operating a specific process, such that it is suitable for operating another process. The obtained IL alkylation unit is used to produce alkylate by reacting an

isoparaffin with an olefin in the presence of an IL catalyst under alkylation conditions. Typical IL

alkylation conditions (or process conditions) are known in the art, whereby it will be appreciated that actual operational process conditions are among others dependent of the exact composition of the reactants and catalyst.

The temperature in the reactor unit is preferably in the range of from -20 to 100⁰C, more preferably in the range of from 0 to 50⁰C, however the temperature must be high enough to ensure that the ionic liquid is in its liquid form.

To suppress vapour formation in the reactor, the process is performed under pressure, preferably the pressure in the reactor is in the range of from 0.1 to 1.6 MPa. - A -

The alkylation process may be a semi-continues or continuous process. Typically, the isoparaffin is an isobutane or an isopentane and the olefin is an olefin comprising in the range of from 2 to 8 carbon atoms, more preferably of from 3 to 6 carbon atoms, even more

preferably 4 or 5 carbon atoms. Examples of suitable olefins include, propene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, 2-methyl-l-butene, 3-methyl-l- butene, 2-methyl-2-butene .

In an IL alkylation process, fresh isoparaffins and olefins are supplied to the process in a molar ratio, which is preferably 1 or higher, and typically in the range of from 1:1 to 40:1, more preferably 1:1 to 20:1. In the case of continuous reaction, the excess

isoparaffin can be recycled to the reactor unit by recycling one or more isoparaffin-comprising streams.

Reference herein below to downstream is to the direction of the fluid flow path from the reactor unit to the fractionator unit. Reference herein upstream is to the opposite direction, i.e. from the fractionator unit to the reactor unit.

Existing HF and SA alkylation units comprise at least a reactor unit for contacting the reactants with the catalyst. The reactor unit preferably comprises at least one reactant inlet and at least one reactor effluent outlet. Preferably, the reactor unit also comprises at least one catalyst inlet. A typical reactor unit provided in sulphuric alkylation unit is a so-called Stratco contactor. In e.g. a Stratco contactor, the hydrocarbon reactants are introduced into an U-shaped reactor fluid flow path together with the catalyst. For HF alkylation typical reactors include e.g. Stratco contactors, gravity circulation reactors and emulsion reactors. Generally, cooling tubes are provided in the reactor fluid flow path to remove the heat generated by the exothermic alkylation reaction. Alternatively, cooling is applied to the acid recycle stream. The effluent of the reactor unit is a mixture of catalyst and a hydrocarbon phase, the latter comprising an alkylate and unreacted reactants, predominantly isoparaffin.

The effluent of the reactor unit is normally provided to a separator unit to separate the reactor effluent into a catalyst phase and an alkylate-comprising hydrocarbon phase. Preferably, the separator unit comprises at least one inlet, typically for the reactor effluent or a stream generated there from, and at least one catalyst phase outlet and at least one alkylate-comprising hydrocarbon phase outlet.

The separator unit serves to separate the effluent of the reactor unit into an alkylate-comprising hydrocarbon phase and a catalyst phase. Preferably, the separator unit used in the HF and SA alkylation units to be

revamped is a settler unit. Due to the low affinity of the HF and SA catalyst for hydrocarbons, the two phases separate readily under the influence of gravity.

Reference herein to a settler unit is to any separator unit that separates two liquid phases under the influence of gravity. Actually, HF, SA and IL catalysts all have a density, which is higher than that of the hydrocarbon phase, therefore the reactor effluent is typically separated in the settler in an upper hydrocarbon phase and a lower catalyst phase.

In case of SA alkylation, catalyst phase recycle means are provided to recycle SA catalyst from the settler unit to the reactor unit. Typically, to maintain catalyst activity, part of the SA catalyst is removed from the process as spent catalyst and fresh SA catalyst is added to keep catalyst levels and activity intact.

In case of HF alkylation, the HF catalyst is

regenerated and recycled to the process for reuse. For this reason, an HF alkylation unit comprises catalyst phase recycle means to recycle the HF catalyst, combined a separate regeneration.

In both SA as HF alkylation, the alkylate-comprising hydrocarbon phase, which was obtained in the settler is, at least in part, provided to a fractionator unit to obtain the retrieve the alkylate. The fractionator unit preferably comprises at least one alkylate-comprising hydrocarbon phase inlet. The fractionator unit,

typically, comprises one or more distillation sub-units, including for instance a main fractionator (also referred to in the art as iso-stripper) , an acid stripper and/or a depropaniser .

Following the fractionation, the obtained alkylate may be used to prepare avgas or as a blending component for gasoline. The hydrocarbon phase may also comprise significant amounts of unreacted isoparaffin. Preferably, such isoparaffin is at least partly recycled back to the reactor unit, via a provided means for recycling

isoparaffin from the fractionator unit to the reactor. Other hydrocarbon streams may also be obtained by

fractionation of the hydrocarbon phase, such a n- paraffin-comprising stream.

In existing HF or SA alkylation units means are provided to allow the reactants and catalyst to enter the reactor and to provide the reactor effluent to the separator unit and subsequently the alkylate-comprising hydrocarbon phase to the fractionator unit. It is not necessary to pass the reactor effluent directly from the reactor unit to the separator unit. The reactor effluent may undergo intermediate treatment such as cooling or heating in a heat exchanger. The same applies for the alkylate-comprising hydrocarbon phase being provided to the fractionator unit. Typically, a fluid flow path for the reactants, products and catalyst is created by providing means to introduce reactants and catalyst to the reactor unit. In addition, means are provided to provide reactor effluent from the reactor effluent outlet of the reactor unit to the reactor effluent inlet of a separator unit located downstream from the reactor unit in the fluid flow path. Also, means are provided to provide an alkylate-comprising hydrocarbon phase from the alkylate-comprising hydrocarbon phase outlet of the separator unit to the alkylate-comprising hydrocarbon phase inlet of a fractionator unit located downstream from the separator unit in the fluid flow path and catalyst phase recycle means are provided to recycle catalyst from the settler unit to the reactor unit.

Ionic liquids are known in the art for their ability to catalyse alkylation reactions. The catalyst used in the present invention is a composite ionic liquid

comprising cations derived from a hydrohalide of an alkyl-containing amine, imidazolium or pyridine.

Preferably, the cations comprise nitrogen atoms, which are saturated with four substituents, among which there is at least one hydrogen atom and one alkyl group. More preferably, the alkyl substituent is at least one

selected from methyl, ethyl, propyl, butyl, amyl, and hexyl groups. Examples of suitable cations include triethyl-ammonium (NEt₃H⁺) and methyl- diethyl-ammonium cations (MeNEt₂H⁺) or

The anions of the composite ionic liquid are

preferably aluminium based Lewis acids, in particular aluminium halides, preferably aluminium (III) chloride. Due the high acidity of the aluminium chloride Lewis acid it is preferred to combine the aluminium chloride, or other aluminium halide, with a second or more metal halide, sulphate or nitrate to form a coordinate anion, in particular a coordinate anion derived from two or more metal halides, wherein at least one metal halide is an aluminium halide. Suitable further metal halides, sulphates or nitrates, may be selected from halides, sulphates or nitrates of metals selected from the group consisting of Group IB elements of the Periodic Table, Group HB elements of the Periodic Table and transition elements of the Periodic Table. Examples or suitable metals include copper, iron, zinc, nickel, cobalt, molybdenum, or platinum. Preferably, the metal halides, sulphates or nitrates, are metal halides, more preferably chlorides or bromides, such as copper (I) chloride, copper (II) chloride, nickel (II) chloride, iron (II) chloride. Preferably, the molar ratio of the aluminium compound to the other metal compounds in the range of from 1:100-100:1, more preferably of from 1:1-100:1, or even more preferably of from 2:1-30:1. By using a

coordinate anion comprising aluminium and another metal, an improved alkylate product may be obtained. A method for preparing such catalyst is for instance described in US7285698. Particularly preferred catalysts are acidic ionic liquid catalysts comprising a coordinate anion derived from aluminium (III) chloride and copper (II) chloride or aluminium (III) chloride and copper (I) chloride.

It has now been found that the less than optimal results reported by Liu et al, are at least in part caused by the different chemical and physical properties of the IL catalyst.

One difference is the activity of the IL catalyst.

Due to the high activity, local depletion of the reaction mixture may occur and undesired side reactions, such as olefin polymerisation, disproportionation reactions or the formation of hydrocarbon halides may occur. Another difference is the desired higher ratio of isoparaffin to olefin inside the reactor. Yet another difference is the higher viscosity of the IL catalyst, which leads to a less effective mixing of the reactants and catalyst in e.g. a Stratco-contactor, again leading to local

depletion of reactant and side-reactions, but which may also lead to the creation of hotspots due to insufficient dissipation of the heat of reaction. Yet another

difference is the optimal reaction temperature, which is typically lower for IL alkylation for instance than for HF alkylation. As a result the reaction mixture must be cooled to lower temperatures, placing a higher cooling requirement on the Stratco contactor.

Therefore, in the first method according to the present invention the reactor unit in the HF or SA alkylation unit to be revamped is adapted by providing a means for recycling at least part of the reactor effluent from the reactor effluent outlet of the reactor unit to the reactant inlet of the reactor unit. Such means allow recycling of at least part of the reactor effluent prior to the separation of the reactor effluent in a catalyst phase and an alkylate-comprising hydrocarbon phase. The HF or SA alkylation unit to be revamped may also be adapted by providing a means for recycling at least part of the alkylate-comprising hydrocarbon phase from the alkylate-comprising hydrocarbon phase outlet of the separator unit to the reactant inlet of the reactor unit. Such means allow recycling of at least part of the alkylate-comprising hydrocarbon phase prior to

fractionation. It will be appreciated that in some cases the original reactor unit is replaced by a new reactor unit rather than adapting the existing reactor.

The HF or SA alkylation unit to be revamped may furthermore be adapted by replacing the original reactor unit by a loop reactor. It will be appreciated that any combination of the above-described methods is also possible. Preferably, at least a means for recycling at least part of the alkylate-comprising hydrocarbon phase from the alkylate-comprising hydrocarbon phase outlet of the separator unit to the reactant inlet of the reactor unit is provided. Preferably, the means for recycling at least part of the alkylate-comprising hydrocarbon phase are provided such that the recycled alkylate-comprising hydrocarbon phase may be mixed with the at least part of the reactants prior to entering the reactor unit through the reactant inlet. Preferably, if there is more than one reactant inlets, the means for recycling at least part of the alkylate-comprising hydrocarbon phase are provided such that the recycled alkylate-comprising hydrocarbon phase may be mixed with the at least part of the

reactants prior to directing the reactants to the

individual reactant inlets. Preferably, at least one static mixer device is provided in the reactor unit or loop reactor. Preferably, the static mixer device is located between the reactant inlet and reactor effluent outlet. Preferably, the static mixer is placed directly after the reactant inlet or even the inlet may be inside or overlap with the static mixer itself. It is also possible and preferred to adapt the reactor unit or a loop reactor by providing two or more reactant inlets each followed by a separate static mixer device located between two subsequent reactant inlets. Alternatively, the reactor unit or loop reactor is adapted to comprise two or more reactant inlets and at least one static mixer device overlaps with at least two inlets .

By adapting the reactor unit as described herein above or replacing the reactor unit with loop reactor, a alkylation unit may be obtained comprising a reactor unit, which combines a large reactant recycle with an operation under plug flow conditions, i.e. back-mixing is minimised. Typically, the adapted reactor or loop reactor is a tube reactor comprising one or more parallel and/or serial aligned tubular passageways. Reference herein to a loop reactor is to a reactor wherein the recycle of the reactor effluent incorporated into the reactor by

circulating a mixture of reactants, products and catalyst continuously, while introducing reactants at one or more inlets and withdrawing part of the circulating mixture at via one or more outlets.

By revamping an HF or SA alkylation unit using the method according to the invention, it is possible to provide a high isoparaffin to olefin molar ratio inside the reactor unit, i.e. isoparaffin to olefin molar ratios of 20 or higher, preferably over 100, which cannot be provided by recycling the hydrocarbons recovered during the fractionation of the hydrocarbon phase using typical fractionator units provided with existing SA or HF alkylation units. Existing SA or HF alkylating units are designed for alkylation processes wherein the isoparaffin to olefin ratio is in the range of 2 to 10 and therefore the typical fractionator units are much to small to provide an isoparaffin recycle stream that is large enough to provided an reactor unit internal isoparaffin to olefin molar ratio above 20 or even 100. By providing means to recycle the alkylate-comprising hydrocarbon phase, a smaller volume needs to be recycled, while the volume of hydrocarbons recycles remains the same compared to recycling part of the reactor effluent.

By providing at least one static mixer device in the reactor, it is possible to create a large interface between the hydrocarbon and catalyst phases, preferably upon entry of fresh reactants into the reactor unit or shortly thereafter. This allows rapid mass transfer of isoparaffin from the hydrocarbon phase, i.e. the

isoparaffin and olefin to the catalyst phase and rapid dissipation of heat of reaction thereby preventing the creation of localised high temperatures areas or volume elements .

The high isoparaffin to olefin ratio and improved mixing efficiency of the loop reactor according to the invention results in high selectivity towards the

formation of alkylate by a reaction of an isoparaffin with an olefin, while reducing the amounts of organic halides and oligomers or polymers formed.

Preferably, the means for recycle of the reactor effluent/alkylate-comprising phase or the loop reactor comprises a means to apply a high shear to a circulating liquid mixture, such as for instance a circulating pump. By applying high shear to a liquid alkylation mixture a large inter-phase surface area may be may be obtained.

The reactor preferably comprises at least one

reactant inlet for introducing olefin and/or isoparaffin. It is preferred that the reactants inlet is provided with individual dispersion devices, e.g. atomizing nozzles, intended to produce a fine disperse phase into a

circulated liquid alkylation mixture, which may comprise unreacted hydrocarbons, alkylate and catalyst.

The reactor preferably also comprises at least one outlet for reactor effluent, which may be used to provide reactor effluent to the settler.

In between an inlet and an outlet a static mixer is located, i.e. the static mixer is located in the fluid flow path downstream from the inlet and upstream from the outlet. Reference herein, to a static mixer is to a device compressing one or more mixer elements and which mixes without an external power source. Preferably, the static mixer is located close to the inlet to ensure that the reactants, which are introduced via the inlet, are rapidly mixed with the circulating alkylation mixture.

More preferably, two or more reactant inlets are provided. Preferably, each reactant inlet is followed by a separate static mixer, wherein the static mixers are provided in between two subsequent reactant inlets and before the reactor effluent outlet, i.e. each static mixer is located in the fluid flow path downstream of a first inlet and upstream of the subsequent inlet or the outlet. Equally preferable, one or more static mixers are provided which extend from a reactants inlet to and beyond one or more subsequent reactant inlets located downstream of the first reactant inlet. The number of inlets is dependent on the size of the reactor and the desired molar ratio of isoparaffins to olefins in the reactor. Preferably, the distance between the reactants inlets in terms of residence time is larger than the residence time required for nearly complete conversion, i.e. 90 mol% or more based on the olefin feed to the reactor unit.

It is also possible to provide the reactor unit or loop reactor with two or more reactor effluent outlets, e.g. to reduce the volume which has to be withdrawn via a single outlet.

It has also been found that the less than optimal results reported by Liu et al, are at least in part caused by the different deactivation/reactivation

behaviour of the IL catalyst.

Therefore, the present invention also provides a second method for revamping an HF or sulphuric acid alkylation unit to an ionic liquid alkylation unit, wherein the HF or sulphuric acid alkylation unit comprise at least:

a reactor unit for contacting catalyst and hydrocarbon reactants;

a separator unit for separating a reactor effluent into a catalyst phase and an alkylate-comprising hydrocarbon phase, ;

a fractionator unit for fractionating the alkylate- comprising hydrocarbon phase into at least one stream comprising alkylate, ; and

a catalyst phase recycle means to recycle at least part of the catalyst phase from the separator unit to the reactor unit;

which method includes: adapting the catalyst phase recycle means by providing a means for acid injection into the catalyst recycle means .

In case of SA alkylation, the spent SA catalyst is discarded or regenerated off-site. Therefore, a

conventional SA alkylation unit will not comprise any catalyst regeneration unit. In HF alkylation, the

catalyst is recycled and regenerated. However, HF

regeneration takes place by removal of water and acid soluble oils (ASO) from the HF. Such regeneration

treatment is not sufficient to regenerate an IL catalyst. In order to restore at least part of the IL catalyst activity it is preferred to introduce a suitable acid to the, at least partly, deactivated catalyst. Preferably, such acid is a halo acid, more preferably hydrochloric acid. For instance, the catalyst may be contacted with hydrogen chloride to rejuvenate the catalyst. This can be done by introducing hydrogen chloride or another suitable acid into the reactor unit or into at least part of the reactor effluent, which comprises at least part of the acidic ionic liquid catalyst. Preferably, hydrogen chloride or another suitable acid is contacted with at least part of the reactor effluent, which comprises at least part of the acidic ionic liquid catalyst. More preferably, the hydrogen chloride or another suitable acid is contacted with the IL catalyst after separation from the hydrocarbons in the settler unit.

In the second method according to the present

invention a catalyst phase recycle means for providing HF or SA catalyst from the separator unit to the reactor unit is adapted, by additionally providing a means for acid injection into the catalyst phase recycle means, i.e. between the separator unit and the reactor unit. Suitable means for acid injection comprise gas and liquid injectors or gas bubblers, preferably combined with a suitable storage vessel for the acid. For instance, in case of a hydrogen chloride injection, the means for injecting an acid may comprise a gas injector or bubbler fluidly connected to a vessel for storing gaseous hydrogen chloride. Suitably circulation means comprising a venturi absorber may be provided to circulate at least part of the catalyst phase recycle and mix it with the gas cap using the venturi absorber.

The hydrogen chloride reacts with the acidic ionic liquid catalyst. Hydrogen chloride is added until no hydrogen chloride is consumed any longer, i.e. until saturation. Hydrogen chloride consumption can be followed by measuring the pressure decrease. Preferably, the addition of hydrogen chloride is done in regular steps, while measuring the pressure in between each addition step. By adding the hydrogen chloride in small steps the creation of an undesired hydrogen chloride gas cap upon saturation is reduced. To follow the hydrogen chloride pressure it is preferred that a means for measuring the pressure is provided in the catalyst recycle or the reactor unit.

Although some gaseous hydrogen chloride in the reactor unit may be tolerated, it is undesired to accumulate unreacted gaseous hydrogen chloride in the reaction system as a result of over-saturation of the acidic ionic liquid with hydrogen chloride. Residual gaseous hydrogen chloride may be purged from the reaction system by providing for instance a means for flushing with an inert gas such as nitrogen. However, this would require additional means for providing nitrogen gas and subsequent storage and treatment of hydrogen chloride- contaminated nitrogen gas. In addition, part of the hydrogen chloride is provided for rejuvenation is lost. Preferably, such hydrogen chloride accumulation is reduced by mixing additional spent acidic ionic liquid catalyst, e.g. in the form of a spent catalyst-comprising stream, into the rejuvenated and recycled acidic ionic liquid catalyst phase effluent, i.e. the recycled

catalyst phase comprising added hydrogen chloride.

Reference, herein to spent acidic ionic liquid catalyst is to an acidic ionic liquid catalyst, which has been used as a catalyst in a chemical reaction and has not yet been rejuvenated with hydrogen chloride. By allowing the spent acidic ionic liquid to react with the gaseous hydrogen chloride present due to initial over-saturation, at least part of the remaining hydrogen chloride may be consumed. The spent ionic liquid catalyst may be

introduced from an external source, however, preferably means are provided in the catalyst phase recycle means allow part of the ionic liquid catalyst to bypass the rejuvenation and subsequently mix the rejuvenated and bypassed streams.

It has also been found that the less than optimal results reported by Liu et al, are at least in part caused by the formation of solids during the alkylation process.

During the operation of an IL alkylation process, solids may be formed. As the reaction progresses, these solids may accumulate in the reaction mixture in the reactor unit.

Therefore the present invention also provides a third method for revamping an HF or sulphuric acid alkylation unit to an ionic liquid alkylation unit, wherein the HF or sulphuric acid alkylation unit comprise at least:

a reactor unit for contacting catalyst and hydrocarbon reactants;

- a separator unit for separating a reactor effluent

into a catalyst phase and an alkylate-comprising hydrocarbon phase;

a fractionator unit for fractionating the alkylate- comprising hydrocarbon phase into at least one stream comprising alkylate; and

which method includes:

providing a second separator unit suitable for the separation of solids from liquids downstream of the reactor unit suitable to reduce the solids content in at least part of the reactor effluent.

By removing at least part of the solids formed during the alkylation reaction, the accumulation of solids in the reaction mixture may be prevented.

Reference, herein to solids is to non-dissolved solid particles. In HF or SA alkylation processes, no

significant amounts, if any, of solids are produced.

Therefore, no means are provided to remove these solids.

The solids predominantly consist out of metals, metal compounds and/or metal salts, which were originally comprised in the acidic liquid catalyst. Additionally, the solids may comprise compounds, which were formed by a chemical reaction including any of the above-mentioned compounds. Typically, the solids comprise at least 10wt% metal, i.e. either in metallic, covalently bound or ionic form, based the total weight of the solids, wherein the metal is a metal that was introduced to the process as part of the acidic ionic liquid catalyst. The solids may also comprise components, which were introduced into the reaction mixture as contaminants in the hydrocarbon mixture or the acidic ionic liquid.

The solids may have any size, however it was found that the solids typically have an average size of in the range of from 0.1 to lOμm. In particular, at least 50% of the solids have a particle size below 5μm, more

particular 80% of the solids have a particle size below 5μm based on the total number of solid particles.

Although, during the alkylation reaction in the reactor unit, the solids may be dispersed, upon

separation of the reactor effluent in the settler unit it has been found that the solids, i.e. to a large extent, accumulate in the IL catalyst. This is due to the high density of the solids. The IL catalyst is subsequently recycled to the reactor unit together with the solids. As a result, the solids accumulate in the reactor unit, resulting in undesirable solids content in the reactor unit, but also in the reactor effluent. A high solids content in the reaction mixture may for instance result in blockage of pathways or valves in the reactor unit and pipes to and from the separator unit, due to

precipitation of solids. In addition, at high solids content the solids may agglomerate to from large

aggregates, resulting in increased blockage risk.

In the third method according to the present

invention a second separator unit, suitable for the separation of solids from liquids is provided. Such a second separator unit may be any separator unit suitable for the separation of a solid from a liquid, including but not limited to filtration, precipitation and

centrifugation units. Such processes are well known in the art. It will be appreciated that the second separator unit may be comprised of two or more similar or different separation sub-units suitable for the separation of a solid from a liquid. Preferably, the second separator unit comprises one or more centrifugal separator units.

Due to the specific nature of the IL catalyst it is preferred that the removal of the solids is performed at such a temperature that the IL catalyst is liquid.

Preferably, the second separator unit can be operated at a temperature in the range of from 5 to 80⁰C, more preferably of from 20 to 60⁰C. By removing the solids at elevated temperatures, the viscosity of the IL is lower while the density of the IL is reduced, which may be beneficial in view of the decreased time and power input required to obtained separation of the solids from the liquid.

The second separator unit may be provided at any suitable place in the HF or SA alkylation unit, which is revamped. The second separator unit may be integrated with the reactor unit to remove the solids directly from the reaction mixture inside the reactor. However, preferably, the second separator unit is provided

downstream of the reactor unit. For instance, upstream of the first separator unit, i.e. the settler unit for separation the hydrocarbon phase from the catalyst. In this way at least part of the reactor effluent may be treated to remove the solids. However, as mentioned herein above, the solids accumulate in the catalyst phase in the settler unit. Therefore, it is more preferred to remove the solids from the catalyst prior to

reintroducing the catalyst into the reactor unit, i.e. downstream from the settler unit in the catalyst phase recycle means. In case of a revamp of an HF or SA

alkylation unit this can be done by adapting the catalyst phase recycle means by providing a second separator unit suitable for separating solids from a liquid.

It is not required to remove all solids. Preferably, solids are removed to an extent that the reactor unit comprises at most 5wt%, preferably in the range of from 0.05 to 5wt%, more preferably of from 0.1 to 2wt% of solids based on the total weight of the ionic liquid catalyst in the reactor unit.

Although, it is believed that part of the catalyst is lost when forming the solids, the catalyst alkylation performance is not significantly affected. Loss of the catalyst due to solids formation merely means that a small fraction of the total catalyst inventory is

inactivated, while the remainder of the catalyst remains unaffected.

The solids may be removed from the process in any form, typically the solids will be removed in the form of a slurry of solids. Such a slurry may comprise next to the solids for instance some residual acidic ionic liquid. Preferably, means are provided to further treat the slurry by extracting the residual acidic ionic liquid. This is preferably done using a liquid-liquid extraction process with a suitable solvent. Due to the virtual absence of an ionic liquid vapour pressure, the solvent can be easily recovered by for instance

evaporation and subsequent condensation. The recovered solvent can be reused.

The solids, which are removed from the process may be discarded, however it is preferred to reuse the

components in the solids, for example in the preparation of fresh IL catalyst.

It has also been found that the less than optimal results reported by Liu et al, are at least in part caused incomplete separation of the hydrocarbon phase and the catalyst phase in the separator unit, i.e. the settler unit.

Due to the different properties of an IL catalyst compared to SA or HF the separation of an IL catalyst from a hydrocarbon phase is different from the separation of either SA or HF from a hydrocarbon phase. As a

consequence, the settler design of the HF or SA

alkylation unit may not provide sufficient separation capacity for separation the hydrocarbon and catalyst phases. As a result catalyst remains in the hydrocarbon phase and vice versa. As a result, catalyst consumption increases and additionally, the hydrocarbon phase is contaminated with catalyst. In addition, the hydrocarbon recycle volumes may increase due to the higher

isoparaffin to olefin molar ratios used in an IL

alkylation process. In a typical HF and SA alkylation processes, the isoparaffin to olefin molar ratios used is in the range of 1 to 10. For an IL alkylation process the isoparaffin to olefin molar ratios used are preferably above 20 or even above 100.

Therefore the present invention also provides a fourth method for revamping an HF or sulphuric acid alkylation unit to an ionic liquid alkylation unit, wherein the HF or sulphuric acid alkylation unit comprise at least:

a reactor unit for contacting catalyst and hydrocarbon reactants;

which method includes:

- providing one or more cyclone units downstream of the reactor unit to separate at least part of the reactor effluent in a catalyst phase and a alkylate-comprising hydrocarbon phase.

In current HF or SA alkylation units, settler units are provided to separate the HF or SA catalyst and the hydrocarbon phase from the reactor effluent. Using the existing settlers, designed to separate HF or SA from hydrocarbons, for separating IL catalyst and the

alkylate-comprising hydrocarbon phase from the reactor effluent after the HF or SA alkylation unit has been revamped to and IL alkylation unit may result in several undesired effects, including:

large settler volumes and undesirable large

inventories of liquefied light hydrocarbons due to high hydrocarbon recycle;

carry over of catalyst to downstream hydrocarbon treating equipment;

contamination of alkylate-comprising hydrocarbon phase, resulting in off-spec products;

- formation of hydrocarbon-catalyst emulsions in the

settler, resulting in operational problems for settler level control;

decreased catalyst rejuvenation regeneration

effectiveness, both in terms of capital cost (larger equipment) and effectiveness of catalyst activity recovery due to the inclusion of a larger fraction of alkylate-comprising hydrocarbon phase in the catalyst. Therefore, in the fourth method according to the invention HF or SA alkylation unit to be revamped

preferably comprises as the separator unit, a settler unit .

In the fourth method according to the present invention a cyclone unit is provided downstream of the reactor unit and means are provided to provide at least part of the reactor effluent to the cyclone unit to enhance separation of the catalyst phase and hydrocarbon phase. Using a cyclone unit it is possible to separate the reactor effluent into a lower density effluent comprising predominantly an alkylate-comprising

hydrocarbon phase and a higher density effluent

predominantly comprising an acidic ionic liquid catalyst phase. The cyclone unit may comprise one or more cyclone sub-units in series. Preferably, the cyclone unit

comprises one or more hydro-cyclones. Reference herein to a hydro-cyclone is to a cyclone designed for the

separation of water-hydrocarbon mixtures. More

preferably, the cyclone unit comprises two or more cyclones or hydro-cyclones in series, wherein the low density predominantly alkylate-comprising hydrocarbon phase effluent of the first (hydro-) cyclone is provided to the next (hydro-) cyclone . This allows a further enhancement of the separation between the IL catalyst phase and the hydrocarbon phase. Preferably, the one or more cyclone units are provided in addition to the existing settler unit. Preferably, the one or more cyclone units are provided upstream of the settler unit and means are provided to pass the lower density, predominantly alkylate-comprising hydrocarbon phase effluent from the cyclone unit to the settler unit.

Equally preferable, the separator unit of the HF or SA alkylation unit to be revamped is replaced by one or more cyclone units.

The higher density effluent of the cyclone unit, which comprises predominantly catalyst phase, can be recycled to the reactor unit, optionally after being combined with catalyst phase obtained in the settler unit, if present.

Optionally, two or more cyclones units can be applied in parallel to increase the capacity. These parallel cyclones units can be combined in series with one or more settlers. By combining one or cyclones with one or more settlers located downstream from at least one of the cyclones, the ionic liquid fraction in lower density, predominantly alkylate-comprising hydrocarbon, effluent may be lowered even further by subjecting the lower density, predominantly alkylate-comprising hydrocarbon phase effluent to a further physical separation

treatment. Although, a settler unit may be relatively large in volume compared to e.g. a cyclone, if a settler unit is used downstream of a cyclone unit, the invention still provides an advantage as the settler unit will be much smaller than a settler unit in a conventional process, which is used to separate the reactor effluent.

The method according to the present invention may also include a combination of the first method with the second, third and/or fourth method according to the invention and described herein above.

Alternatively, the method according to the present invention may also include combinations of the second method with the third and/or fourth method according to the invention and described herein above. For instance, by combining the second and third method according to the invention , means are provided to, during operation of an IL alkylation process, replace any chlorine that is lost with the formation and removal of the solids by the addition of hydrogen chloride during rejuvenation. It is a particular advantage that both the second separator unit for removing solids and the means for acid injection can be provided in the same catalyst recycle means.

In another alternative, method according to the present invention may also include a combination of the third method with the fourth method according to the invention and described herein above.

By combining the methods as described herein above a synergistic effect may be obtained, which may further increase the suitability of the revamped alkylation unit for IL alkylation. For instance, by combining the first and fourth method it is possible to revamp the existing SA or HF alkylation unit by providing a recycle of hydrocarbons from the separator unit back to the reactor unit to allow for a high isoparaffin to olefin molar ratios in the reactor during operation of a IL alkylation process, while providing a cyclone unit as the separator unit to allow continuous fast separation of hydrocarbons and IL catalyst during operation of the IL alkylation process. By doing so the need to maintain a large

hydrocarbon inventory in the separator (settler) unit is removed.

In addition, by combining for instance the second and third method according to the invention , means are provided to, during operation of an IL alkylation

process, replace any chlorine that is lost with the formation and removal of the solids by the addition of hydrogen chloride during rejuvenation. It is a particular advantage that both the second separator unit for removing solids and the means for acid injection can be provided in the same catalyst recycle means.

In Figure 1 a schematic representation is given of a typical SA alkylation unit not according to the

invention.

In Figure 1, a hydrocarbon mixture, comprising olefin and isoparaffin is provided to reactor unit 100, e.g. a Stratco contactor, via conduit (e.g. a pipe) 105, through reactant inlet 107. Catalyst, SA or IL, is also provided to reactor unit 100 through conduit 110 and catalyst inlet 113. In reactor unit 100, the hydrocarbon mixture and catalyst are contacted under alkylation conditions. Through reactor effluent outlet 114, a reactor effluent comprising catalyst and hydrocarbons is withdrawn from reactor unit 100 and supplied via conduit 115 to settler unit 120 through reactor effluent inlet 122. In settler unit 120, an alkylate-comprising hydrocarbon phase and a catalyst phase separate under influence of gravity. The hydrocarbon phase is withdrawn from separator unit 120 via alkylate-comprising hydrocarbon phase outlet 123 and provided to fractionator unit 125 through conduit 130 and alkylate-comprising hydrocarbon phase inlet 133. From the bottom of fractionator unit 125, an alkylate-comprising product is retrieved through conduit 135. The alkylate product can for instance be used for fuel blending purposes. Additionally, an isoparaffin product is retrieved from fractionator unit 125, which is recycled via conduit 140 to become part of the hydrocarbon mixture in conduit 105. Other hydrocarbon-comprising streams (not shown) may also be retrieved from fractionator 125.

The catalyst phase is withdrawn from separator unit 120 through catalyst phase outlet 143 and can be recycled via catalyst phase recycle conduit 145 to reactor unit 100. A spent catalyst fraction may be withdrawn from the process via conduit 150. Additional fresh catalyst can be provided to reactor unit 100 via conduit 155

In Figure 2A a schematic representation is given of a SA alkylation unit as described in Figure 1, which was revamped using the method according to the invention, wherein the reactor effluent is recycled to the inlet for reactants of reactor unit 100. The arrow indicates the flow direction in reactor unit 100. In Figure 2A, conduit 105 for providing the reactants to reactor unit 100 is split to provide reactants to both first reactant inlet 205 via conduit 207 and via conduit 210 to second

reactant inlet 212, located downstream of first reactant inlet 205. Overlapping with and extending downstream of reactant inlet 205, first static mixer 215 is placed and overlapping with and extending downstream of reactant inlet 210, second static mixer 220 is placed.

A reactor effluent is withdrawn from reactor unit 100 via reactor effluent outlet 114. A part of the reactor effluent is provided to separator unit 120 via conduit

115. Another part of the reactor effluent is recycled to reactor inlet 205 via reactor effluent recycle conduit 225. In figure 2A, the recycled reactor effluent is combined with the reactants in reactant conduit 207, however it is also possible to supply the recycled reactor effluent directly to reactant inlet 205 or a separate recycled reactor effluent inlet (not shown) Circulation pump 230 has been provided in reactor

effluent recycle conduit 225 to assist the recycling of reactor effluent to reactor unit 100.

In Figure 2B, reactor effluent recycle conduit 225 has been replaced by alkylate-comprising hydrocarbon phase recycle conduit 240. In Figure 2B, an alkylate- comprising hydrocarbon phase is withdrawn from separator unit 120 via alkylate-comprising hydrocarbon phase outlet 123. A part of the alkylate-comprising hydrocarbon phase is provided to fractionator unit 125 via conduit 130. Another part of the alkylate-comprising hydrocarbon phase is recycled to reactor inlet 205 via alkylate-comprising hydrocarbon phase recycle conduit 240. In Figure 2B, the recycled alkylate-comprising hydrocarbon phase is

combined with the reactants in reactant conduit 105, however it is also possible to supply the recycled alkylate-comprising hydrocarbon phase to reactant conduit 207 or directly to reactant inlet 205 or a separate recycled alkylate-comprising hydrocarbon phase inlet (not shown) . Circulation pump 230 has been provided in reactor effluent recycle conduit 240 to assist the recycling of alkylate-comprising hydrocarbon phase to reactor unit 100.

In Figure 2C a schematic representation is given of a SA alkylation unit as described in Figure 1, which was revamped using the method according to the invention, wherein reactor unit 100 is replaced by loop reactor unit 200. The arrows indicate the flow direction in loop reactor unit 200. In Figure 2, conduit 105 for providing the reactants to reactor unit 100 is split to provide reactants to both first reactant inlet 205 via conduit 207 and via conduit 210 to second reactant inlet 212, located downstream of first reactant inlet 205.

Overlapping with and extending downstream of reactant inlet 205, first static mixer 215 is placed and extending downstream of reactant inlet 210, second static mixer 220 is placed.

A reactor effluent is withdrawn from loop reactor unit 200 via reactor effluent outlet 245 and conduit 115. Circulation pump 230 has been provided to circulate the reactants and catalyst in loop reactor unit 200.

In Figure 3, a schematic representation is given of a SA alkylation unit as described in Figure 1, which was revamped using the method according to the invention, wherein a means for acid injection into the catalyst recycle means acid is provided. In Figure 3, means 305 for injecting an acid, e.g. a gas injector, is provided in catalyst phase recycle conduit 145. Injector means 305 is fluidly connected to storage vessel 310, wherein an acid such as hydrogen chloride is stored. If required, a part of the recycled catalyst phase may bypass means 305 via bypass conduit 315. Bypass conduit 315 recombines with catalyst phase recycle conduit 145 downstream of acid injection means 305.

In figure 4A, a schematic representation is given of a SA alkylation unit as described in Figure 1, which was revamped using the method according to the invention, wherein a second separator unit suitable for the

separation of solids from liquids is provided. In Figure 4A, part or all of the catalyst phase can be diverted from catalyst phase recycle conduit 145 by conduit 405 to centrifuge 410. In centrifuge 410, solids are removed from the IL catalyst phase under influence of the

centrifugal forces, and are retrieved via conduit 415.

The remaining IL catalyst phase exits centrifuge 410 via conduit 420, which is in fluid connection with catalyst phase recycle conduit 145.

In figure 4B, a schematic representation is given of a SA alkylation unit as described in Figure 1, which was revamped using the method according to the invention comparable to that in Figure 4A. However, in Figure 4B, centrifuge 410 was incorporated directly in catalyst phase recycle conduit 145.

In Figure 5A, a schematic representation is given of a SA alkylation unit as described in Figure 1, which was revamped using the method according to the invention, wherein a cyclone unit is provided between the reactor unit and separator unit. In Figure 5A, the reactor effluent is provided via conduit 115 to cyclone unit 505. The lower density, predominantly alkylate-comprising hydrocarbon, phase from the cyclone unit is provided to settler unit 120 via conduit 510. The higher density, predominantly catalyst, phase is provided to catalyst recycle conduit 145 via conduit 515. A more detailed representation of a possible cyclone unit 505 is given in Figure 5B, wherein reactor effluent enters first cyclone sub-unit 550 in cyclone unit 505 via conduit 115. The lower density phase exits first cyclone sub-unit 550 via conduit 555 and is provided to second cyclone sub-unit 560 for further separation of catalyst phase from the alkylate-comprising hydrocarbon phase. A lower density alkylate-comprising hydrocarbon phase exits second cyclone sub-unit 560 via conduit 565 and is provided to settler unit 120. A higher density catalyst phase is obtained from both first cyclone sub-unit 550 and second cyclone sub-unit 560 via respectively conduit 570 and 575 and may be provided to catalyst recycle conduit 145.

In Figure 6, a schematic representation is given of a SA alkylation unit as described in figure 1, which was revamped using the method according to the invention, wherein:

an alkylate-comprising hydrocarbon phase recycle conduit is provided; Static mixing devices are provided in reactor unit 100;

a means for acid injection into the catalyst recycle means acid is provided;

- a second separator unit suitable for the separation of solids from liquids is provided; and

a cyclone unit is provided between the reactor unit and separator unit.

The reference numbers in Figure 6 correspond to units already described for Figures 1 to 5.

Where figures 1 to 6 refer to a SA alkylation unit, it will be appreciated that the same drawings could be used to represent an HF alkylation unit.

Examples

The invention is illustrated by the following non- limiting examples.

Example 1

An alkylation process was performed in three separate runs to mimic regular solids removal. In between each run the acidic ionic liquid catalyst was separated from the hydrocarbon phase and treated by removing solids and adding hydrogen chloride gas. The treated acidic ionic liquid catalyst was subsequently used in the following run .

The catalyst used was an ionic liquid catalyst comprising a coordinate anion derived from aluminium (III) chloride and copper (I) chloride) (ex China University of Petroleum Beijing) .

At start-up, sufficient isobutane was provided to the test unit to allow for a molar ratio of isoparaffin to olefin in the reactor of above 95.

A hydrocarbon mixture of isobutane and butenes was provided together with the acidic ionic liquid catalyst to the alkylation reactor. The reactor had a volume of 0.4 litre.

The effluent of the alkylation reactor was separated in a settler and part of the hydrocarbon phase was sent to a fractionator, while the remainder of the hydrocarbon phase was recirculated to the reactor.

The alkylate was obtained from the bottom of the fractionator and tested to determine the motor RON and MON values.

An isobutane-comprising stream was recycled from the fractionator back to the hydrocarbon mixture.

The acidic ionic liquid catalyst phase obtained from the settler was recycled to the reactor. Periodically, i.e. between the runs, the acidic ionic liquid catalyst phase obtained from the settler was redirected to a disk centrifuge and centrifuged at 20000 rpm for 1 hour at a temperature of 50⁰C. The weight of solids produced was recorded. Following the solids removal, hydrogen chloride gas was added to the treated acidic ionic liquid catalyst at a pressure of approximately 5 bar at a temperature of 35°C, until no hydrogen chloride was consumed any more. The amount of hydrogen chloride consumed was recorded. The reaction condition and obtained results are listed in Table 1.

It will be clear that:

By providing means to recycle part of the hydrocarbon phase from the separator unit to the reaction

recirculation a high isoparaffin to olefin molar ratio in the reactor is achieved. Recycling the isoparaffin from the fractionator alone cannot provide a high ratio of over 95.

By providing a second separator unit suitable for the removal of solids from the ionic liquid catalyst, approximately 1.5 kg of solids could be removed from the process. In case no solids removal would have taken place the 1.5 kg of solids would have

accumulated in the reactor. By removing the solids, solids content is significantly reduced and the alkylate quality remains high.

By providing a means for acid injection into the catalyst recycle, the ionic liquid catalyst was intermittently rejuvenated, by reacting with hydrogen chloride. As a result catalyst activity and the alkylate quality remains high.

The observed differences in the obtained alkylate properties are caused by the differences in the

alkylation temperature and isoparaffin to olefin ratio.

Table 1

* isobutane/butene ratio, i.e. the isobutane/butene ratio in the mixture of fresh feed and the isobutane recycled from the fractionator

**total weight of the solids slurry

Solids analysis

The solids removed from the acidic ionic liquid catalyst phase were analysed. The size distribution was determined using a laser particle size analyser. The results are shown in Table 2.

Table 2

Example 2

In two subsequent runs (4 and 5) the effect of acid injection was tested.

Run 4

Using the same reactor set-up and conditions as in Example 1, a fourth run was performed using an ionic liquid catalyst intake of 52.46 kg. Corrected for the loss of catalyst due to sampling, the average ionic liquid catalyst inventory during run 4 was 47.25 kg. The catalyst consisted of 79wt%% of fresh ionic liquid, see example 1, and 21wt% of used ionic liquid obtained from run 3, following acid injection and solids removal.

An isobutane/butene mixture was introduced at 25 ⁰C with an average molar ratio of 14 based on a mixture of the recycled excess of isobutane from the fractionator and fresh feed of isobutane and butene, as used in

Example 1. The isobutane/butene mixture was introduced at a feed rate between 2 and 4 kg/h. The acidic ionic liquid catalyst phase obtained from the settler was recycled at an average rate of 270kg/h. An average of 80 kg/h of hydrocarbon phase obtained from the settler was recycled to reactor. No solids were removed during the run . A breakthrough of butenes was detected in the reactor outlet after 195 kg of butenes, i.e. 4.13 kg of butenes per kg of ionic liquid catalyst (based on the average catalyst inventory) , had been fed to the

reactor. The detection of butenes in the reactor

effluent indicates incomplete conversion and

deactivation of the catalyst. The run was subsequently stopped.

Following run 4, the ionic liquid inventory was centrifuged to remove the solids. Subsequently 0.42 kg of HCl was dissolved in the remaining ionic liquid.

Run 5

Using the conditions of run 4 a fifth run was conducted. 52.73 kg of ionic liquid were provided.

Corrected for the loss of catalyst due to sampling, the average ionic liquid catalyst inventory during run 4 was 50.28 kg. The ionic liquid catalyst consisted 28wt% of fresh ionic liquid, see example 1, 21wt% of ionic liquid of used ionic liquid obtained from run 3 following acid injection and solids removal and 51wt% of used ionic liquid obtained from run 4 following acid injection and solids removal. Run 5 was conduct over a period of 7 days. Every 24 hours, approximately 10 kg of ionic liquid was separated off from the ionic liquid catalyst phase obtained from the settler. The separated ionic liquid catalyst was treated by dissolving HCl in the ionic liquid and the resulting ionic liquid catalyst was reinjected in the ionic liquid recycle to the reactor. In total 0.48 kg of HCl were added to the catalyst:

day 1: 0.04 kg,

day 2: 0.04 kg,

day 3: 0.08 kg,

day 4: 0.08 kg, day 5 : 0 . 08 kg,

day 6 : 0 . 08 kg,

day 7 : 0 . 08 kg .

During Run 5, 223 kg of butenes, i.e. 4.43 kg of butenes per kg of ionic liquid catalyst (based on the average catalyst inventory), were fed to the reactor. At the end of the run 5, the butene conversion was still complete and no butenes were identified in the reactor effluent. The ionic liquid catalyst remained active.

It will be clear from runs 4 and 5 that the

periodic addition of HCl to the ionic liquid catalyst prevents catalyst deactivation and increased the run time of the reaction. In addition, it has been shown hat deactivated ionic liquid catalyst may be reactivated or rejuvenated by addition of an acid such as HCl.

Example 3

In order to show the effectiveness of using a cyclone to separate the reactor effluent rather than a conventional settler, a sample reactor effluent, comprising a mixture of hydrocarbon reactants and products and ionic liquid catalyst was separated using a cyclone .

The sample reactor effluent comprises hydrocarbons and ionic liquid catalyst in a volume ratio of 1:1.05. The operating temperature was maintained between 30 and 50⁰C and the operating pressure was maintained between 0.1 to 0.5 MPa. The maximum feed rate of sample reactor effluent to the cyclone was 2 m³/hr.

In a first run, 40vol% of the sample reactor effluent was retrieved as lower density, predominantly alkylate-comprising hydrocarbon, phase. The remaining 60 vol% of the sample reactor effluent was retrieved as higher density, predominantly catalyst, phase. The lower density, predominantly alkylate- comprising hydrocarbon, phase comprised:

95.5vol% of hydrocarbons; and

4.5vol% of ionic liquid,

based on the volume of the lower density, predominantly alkylate-comprising hydrocarbon, phase.

The higher density, predominantly catalyst, phase comprised:

17.7vol% of hydrocarbons; and

- 82.3vol% of ionic liquid,

based on the volume of the higher density, predominantly catalyst, phase.

Using one separator approximately 79vol% of the hydrocarbons originally provided in the sample reactor effluent were recovered in the lower density,

predominantly alkylate-comprising hydrocarbon, phase.

In case the lower density, predominantly alkylate- comprising hydrocarbon, phase is further treated in a upstream settler unit, the size of volume of the settler unit is only 40% of a settler unit used to separate the whole reactor effluent.

In a second run, the sample reactor effluent was separated into a lower density, predominantly alkylate- comprising hydrocarbon, phase and a higher density, predominantly catalyst, phase using two separation steps. The obtained separation results are below.

50 vol% of the feed. i.e. sample reactor effluent, to the centrifuge was retrieved as a, lower density, intermediate phase and the remaining 50 vol% as higher density ionic liquid phase effluent.

The intermediate phase comprised:

93.8vol% of hydrocarbons; and

6.2vol% of ionic liquid, based on the volume of the intermediate phase.

The higher density, predominantly catalyst, phase comprised:

90.0vol% of hydrocarbons; and

- 10.0vol% of ionic liquid,

based on the volume of the higher density, predominantly catalyst, phase.

The obtained intermediate phase was retrieved as an intermediate product and subjected to a second cyclone separation step. During the second cyclone separation step, 85vol% of the intermediate phase was retrieved from the cyclone as, lighter density, hydrocarbon phase effluent and the remaining 15 vol% of the intermediate phase was retrieved as a higher density phase effluent, also referred to a (an) other effluent.

The lower density, predominantly alkylate- comprising hydrocarbon, phase comprised:

98.5vol% of hydrocarbons; and

1.5vol% of ionic liquid,

The other effluent comprised:

68.7vol% of hydrocarbons; and

31.3vol% of ionic liquid,

based on the volume of the other effluent.

Using two separators approximately 86 vol% of the hydrocarbons originally provided in the sample reactor effluent were recovered in the lower density,

predominantly alkylate-comprising hydrocarbon, phase.

By using two separators, in this case cyclones, in series to separate the lower density, predominantly alkylate-comprising hydrocarbon, phase from the sample reactor effluent, an increased fraction of the hydrocarbons in the sample reactor effluent can be retrieved and sent to the fractionator . This is due to the fact that a larger fraction of the reactor effluent is obtained as the intermediate phase from the first separator. Although, passing a larger fraction of the sample reactor effluent to the lighter intermediate phase causes the ionic liquid fraction in this multiple phase effluent to increase, the final ionic liquid fraction in the resulting lower density, predominantly alkylate-comprising hydrocarbon, phase is much lower due to the second separator step. As a result a larger fraction of the hydrocarbons in the reactor effluent can be separated from the ionic liquid. Using only one separator, the lower density, predominantly alkylate- comprising hydrocarbon, phase comprises only 79 vol% of the hydrocarbons originally present in the reactor effluent. In Example Ib, however, 86 vol% of the

hydrocarbons in the reactor effluent were retrieved in the hydrocarbon effluent, comprising less ionic liquid.

In addition, the higher density, predominantly catalyst, phase comprised less hydrocarbons compared using only one separator, even in the case it is combined with the (an) other effluent.

In case the lower density, predominantly alkylate- comprising hydrocarbon, phase is further treated in a upstream settler unit, the size of volume of the settler unit is only 42.5% of a settler unit used to separate the whole reactor effluent.

Claims

C L A I M S

1. A method for revamping an HF or sulphuric acid alkylation unit to an ionic liquid alkylation unit, wherein the HF or sulphuric acid alkylation unit

comprises at least:

- a reactor unit for contacting catalyst and hydrocarbon reactants;

a separator unit for separating a reactor effluent into a catalyst phase and an alkylate-comprising hydrocarbon phase;

- a fractionator unit for fractionating the alkylate- comprising hydrocarbon phase into at least one stream comprising alkylate; and

which method includes one or more of:

iii) replacing the reactor unit by a loop reactor.

2. A method according to claim 1, wherein the method includes at least providing the means for recycling at least part of the alkylate-comprising hydrocarbon phase to the reactor unit.

3. A method according to claim 1 or 2, wherein the reactor unit or loop reactor is adapted to comprise two or more reactant inlets each followed by a separate static mixer device located between two subsequent reactant inlets.

4. A method according to claim 1 or 2, wherein the reactor unit or loop reactor is adapted to comprise two or more reactant inlets and at least one static mixer device, which overlaps with at least two inlets.

5. A method according to any one of the preceding claims, wherein the HF or sulphuric acid alkylation unit further comprises:

which method includes:

- adapting the catalyst phase recycle means by providing a means for acid injection into the catalyst recycle means .

6. A method according to claim 5, wherein the catalyst phase recycle means is further adapted by providing a bypass around the means for acid injection to allow part of the catalyst phase to bypass the acid injection.

7. A method according to any one of the preceding claims,

which method furhter includes:

- providing a second separator unit suitable for the

separation of solids from liquids downstream of the reactor unit suitable to reduce the solids content in at least part of the reactor effluent.

8. A method according to claim 7, wherein catalyst phase recycle means are provided to recycle at least part of the catalyst phase from the catalyst phase outlet of the separator unit to the reactor unit and wherein the second separator is integrated in the catalyst recycle means .

9. A method according to any one of the preceding claims, which method includes:

providing one or more cyclone units downstream of the reactor unit to separate at least part of the reactor effluent in a catalyst phase and a alkylate-comprising hydrocarbon phase.

10. A method according to claim 9, wherein the one or more cyclone units are located upstream of the separator unit.

11. A method according to claim 9, wherein the separator unit is replaced by the one or more cyclone units.

12. A method for revamping an HF or sulphuric acid alkylation unit to an ionic liquid alkylation unit, wherein the HF or sulphuric acid alkylation unit

comprises at least:

a reactor unit for contacting catalyst and hydrocarbon reactants;

which method includes one or more of:

providing a second separator unit suitable for the separation of solids from liquids downstream of the reactor unit suitable to reduce the solids content in at least part of the reactor effluent;

- providing one or more cyclone units downstream of the reactor unit to separate at least part of the reactor effluent in a catalyst phase and a alkylate-comprising hydrocarbon phase; and

the HF or sulphuric acid alkylation unit further comprising a catalyst phase recycle means to recycle at least part of the catalyst phase from the separator unit to the reactor unit adapting the catalyst phase recycle means by providing a means for acid injection into the catalyst recycle means.