EP4204386A1

EP4204386A1 - Process and plant for producing one or more hydrocarbons

Info

Publication number: EP4204386A1
Application number: EP21806224.8A
Authority: EP
Inventors: Andreas Meiswinkel; Hans-Jörg ZANDER
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2020-11-06
Filing date: 2021-11-04
Publication date: 2023-07-05
Also published as: DE102020129303A1; WO2022096592A1; US20230406786A1; CN116507600A

Abstract

The invention relates to a process (100) for producing one or more hydrocarbons, in which process carbon dioxide and/or carbon monoxide is at least partially reacted in a first reaction step with hydrogen in a process gas flow (1), which is fed to a reactor assembly, to give one or more oxygenates which pass(es) into the process gas flow (1), and in which process the one or more oxygenates in the process gas flow (1) is or are at least partially reacted in a second reaction step to give one or more hydrocarbons which pass(es) into the process gas flow (1). The process gas flow (1) is guided in a flow direction through the reactor assembly and the reactor assembly has one or more reactor(s) (10) which has or have a first reaction zone (11) and a second reaction zone (12). The second reaction zone (12) is situated downstream of the first reaction zone (11) in the flow direction, and the first reaction zone (11) and the second reaction zone (12) are equipped with catalysts so that: the first and the second reaction steps are catalysed in the first reaction zone (11); the second reaction step is catalysed in the second reaction zone; and the first reaction step is not catalysed in the second reaction zone (12), or is catalysed to a lesser extent than in the first reaction zone (11). The present invention also relates to a corresponding plant.

Description

description

Process and plant for the production of one or more hydrocarbons

The present invention relates to a method for producing one or more hydrocarbons, in particular ethylene and/or propylene, and a corresponding plant according to the preambles of the independent patent claims.

The project that led to the present patent application was funded under grant agreement No. 837733 of the European Union's Horizon 2020 research and innovation programme.

Background of the Invention

Ethylene and propylene are essential building blocks in petrochemistry. Further continuous growth is expected for both products. Annual demand in 2016 was 150 million t/a for ethylene (capacity 170 million t/a) and 100 million t/a for propylene (capacity 120 million t/a). In particular, an increasing demand for propylene ("propylene gap") is forecast, which requires the provision of corresponding selective processes.

Changes in the supply of raw materials fundamentally affect the petrochemical value chain and cause increased demand for new production methods for the olefins and other hydrocarbons mentioned. At the same time, it is important to reduce the carbon dioxide footprint of corresponding processes and to reduce or, if possible, eliminate carbon dioxide emissions. It is therefore the aim of academic and industrial research work, and also of the present invention, to show alternative production routes for hydrocarbons which also take into account energy and environmental aspects.

The invention therefore aims at an improved process for the production of hydrocarbons from carbon dioxide. In addition to the general configuration, the aim of the invention is in particular the production of paraffins and particularly preferably of olefins. The invention is particularly on the production of Paraffins and olefins having two to eight carbon atoms, but especially two and three carbon atoms, directed. Accordingly, the following explanations are in part strongly geared towards the production of ethylene and propylene. Aromatics can also be formed as by-products. However, the present invention is not limited to these hydrocarbons.

Existing processes for the selective production of olefins are discussed in more detail below. In these processes, significant amounts of carbon dioxide are usually released, either from firing or energy supply in endothermic processes, or as a by-product in oxidative processes. Other by-products are often carbon monoxide and hydrogen, which have also only been used to a limited extent to date and are often used, for example, for firing.

Current research directions, which are also explained in more detail below, are aimed at converting carbon dioxide with hydrogen (possibly also in the presence of carbon monoxide) to form hydrocarbons. The focus is particularly on products with two to four carbon atoms (both paraffins and olefins), especially propylene.

The present invention applies in particular to processes which currently lead to hydrocarbons via methanol and/or dimethyl ether as an (isolated) intermediate stage. This relates to the synthesis of methanol and/or dimethyl ether from synthesis gas, which is explained in more detail below, followed by the methanol-to-olefins or methanol-to-propylene processes, which are also explained in more detail below. According to the prior art, these processes are carried out in two stages, i.e. sequentially in separate reaction steps and over different catalysts.

The object of the present invention is to improve corresponding methods and in particular to design them more advantageously with regard to their energy consumption and/or carbon dioxide footprint. Disclosure of Invention

Against this background, the present invention proposes a method for producing one or more hydrocarbons, in particular ethylene and/or propylene, and a corresponding plant with the respective features of the independent patent claims. Preferred embodiments of the present invention are the subject matter of the dependent patent claims and the following description.

As mentioned, the invention begins with processes which currently lead to hydrocarbons via methanol and/or dimethyl ether as an (isolated) intermediate stage and which are explained in detail further below. Before explaining the specific advantages and features of embodiments of the present invention, however, comparative reference should again be made to other methods that can be used in connection with the present invention, in the broader context thereof, and as an alternative to the present invention.

As mentioned, there is a desire in the chemical industry to reduce the carbon dioxide emissions from synthesis processes and corresponding plants. The resulting carbon dioxide should advantageously be used as a material. In this context, reference is made to the relevant specialist literature listed at the end, in particular references [1] to [6], for illustrative purposes only.

Relevant synthesis processes for the production of olefins such as ethylene and propylene include, for example, steam cracking, in which case inputs such as ethane, propane, so-called liquefied petroleum gas (LPG) or naphtha can be used, and, in particular for the production of propylene, fluid catalytic cracking using an appropriate catalyst. Recent trends in olefin production are given, for example, in [7].

Alternative technologies for the production of ethylene include the fundamentally known oxidative dehydrogenation of ethane (ODH-E), in which acetic acid is formed as a by-product, and the also known oxidative coupling of methane. Processes for the production of propylene include, for example, the established propane dehydrogenation and olefin metathesis, which requires 2-butene as an input. Also modified Fischer-Tropsch processes optimized to produce a maximum yield of light olefins ("Fischer-Tropsch-To-Olefins", FTTO) and Fischer-Tropsch processes combined with a reverse water gas shift (RWGS). are, so that carbon dioxide can also be incorporated, can be mentioned here. In particular, reference is made to specialist literature such as [8] and [9] on FTTO and [10] to [12] on the combination of Fischer-Tropsch methods with RWGS.

In addition, there are a large number of other developments and publications which, among other things, are also based on the use of dimethyl ether (again as an isolated intermediate) and/or attempt to achieve a particularly advantageous product distribution. Again, reference can be made to relevant specialist literature such as [13] to [16].

The production of oxygenates such as methanol and dimethyl ether from synthesis gas is already largely established prior art, as is the combination with so-called methanol-to-olefins or methanol-to-propylene processes (MTO, MTP), which regardless of their Designation can also implement other oxygenates such as dimethyl ether in a comparable manner. Corresponding process combinations represent a further way of producing olefins. For the background and the technical implementation, reference is also made here to the relevant technical literature, see for example [17] to [21],

Technologies for providing synthesis gas, as used in such processes, are also extensively described in the technical literature, see for example [22] to [26]. These include, among other things, partial oxidation and various reforming processes. So-called dry reforming (also referred to as carbon dioxide reforming) with a downstream shift to adjust the hydrogen/carbon monoxide ratio is also established.

The methanol-to-olefins or methanol-to-propylene processes mentioned usually start from methanol and/or dimethyl ether as an isolated intermediate stage, which is produced by converting synthesis gas (e.g. generated from methane, but also from coal, naphtha, etc.) can be made. In particular, olefins such as ethylene and propylene are sought as the preferred target product. Lewis acidic materials, in particular zeolites or, are used as catalysts zeolite-like materials used. By choosing the catalyst material and the exact reaction conditions, the product spectrum can be adjusted, especially with regard to the type of products and their relative distribution. In general, zeolites (basic type ZSM-5, medium porosity) and silicoaluminophosphates (SAPO, especially SAPO-34, low porosity) in particular have nowadays turned out to be the most suitable for a technical application.

Methanol-to-olefins or methanol-to-propylene processes are commercially established and are used, for example, in the form of a methanol-to-propylene process based on a zeolite catalyst and a fixed-bed reactor (one or two reactor systems with an additional reserve reactor are common) and in the form of a methanol-to-olefins process with a catalyst based on SAPO-34. In the former, a main advantage is said to be the simple possibility of expanding the fixed-bed reactor (parallelization) and the significantly lower investment costs, the main aim being propylene as the target product, but significant amounts of heavier fractions are also formed. The advantage of the latter is said to be that in SAPO-34 compared to ZSM-5 there are narrower microcrystalline pores and better control of the acidity can be achieved. Crude methanol is typically used in the latter process and the reactor system used comprises two fluidized bed reactors (one for the actual reaction and one for continuous catalyst regeneration), the process being characterized by temperature, at 350 to 525 O (preferably 350 O), pressure at 1 to 3 barg, the residence time and the regeneration cycle is controlled.

Further developments and optimizations include in particular the combination with an additional catalytic cracking step (Olefins Cracking Process, OCP) for a recycle stream in order to increase the olefin selectivity.

For example, a combination of reforming and so-called Fischer-Tropsch-to-olefins processes via methanol to olefins is also described in the technical literature. Furthermore, there are already approaches to combine a methanol synthesis from synthesis gas and a methanol-to-olefin or methanol-to-propylene process in one step. These approaches are essentially based on a combination of Zr-Zn oxides (for methanol synthesis) and H-SAPO-34 as a methanol-to-olefins or methanol-to-propylene catalyst. There are also already developments for the hydrogenation of carbon dioxide via bifunctional catalysts (for example, review article [27]). In principle, however, corresponding systems also appear suitable for the corresponding conversion of carbon monoxide or any mixtures of carbon monoxide and carbon dioxide to hydrocarbons and in particular to olefins such as ethylene and/or propylene.

The bifunctional catalysts catalyze two reaction steps, namely conversion of the components of synthesis gas to one or more oxygenates such as methanol and/or dimethyl ether as intermediate(s) and further conversion of the intermediate(s) to the desired target compound in the form of one or more hydrocarbons . A bifunctional catalyst used here combines typically used methanol catalysts with acidic zeolite structures which catalyze the subsequent reaction.

Alternatively, the two reaction steps can also take place in parallel using a combination of two or more suitable catalysts, each of which preferably catalyzes the corresponding reaction steps, as a physical mixture in a catalyst bed. Appropriate catalysts can be the above-mentioned catalysts for methanol or dimethyl ether synthesis or for further conversion, which are known in principle.

The overall reaction takes place in both variants when viewed externally as a one-stage reaction, which, however, comprises two individual reactions or reaction steps.

For example, for propylene as the target product, the following individual reactions result from methanol:

CO ₊ 2H2CH3OH AH = -91kJ/mol CO2 + ₃ H2 _CH3OH ₊ H2 O AH = -48 kJ/ _mol3 CH3 OH _C3H6 ₊ _3H2O AH = -104 kJ/mol

As a side reaction or "overhydration" to propane can be observed:

₃ _CH3OH ₊ H2 ^ C3 H8 + ₃ H2 O AH = -227 kJ/mol Classic two-stage reaction systems are to be regarded as disadvantageous compared to a one-stage reaction as described here due to thermodynamic conditions. Various olefins such as ethylene and propylene as well as different amounts of paraffins (ethane, propane) and also heavier hydrocarbons are often formed in the corresponding processes. Aromatics can also be formed as by-products.

Examples of bifunctional catalysts used for converting carbon dioxide are given in Table 1 below.

Table 1

The invention proposes a combination of the two reaction steps mentioned in one reactor or in several reactors with a suitable catalyst (where one or both of the reaction steps according to the above equations (1) and (2) as a first reaction step and the reaction step 3 according to the above Equation (3) is interpreted as the second reaction step.

As illustrated by FIGS. 2A and 2B, to which reference is already made at this point, the use of the present invention results in a significantly higher yield than in a sequential implementation.

The reactions involved are basically thermodynamically limited equilibrium reactions. From this it follows that in principle all species involved (educts such as carbon monoxide, carbon dioxide and hydrogen, intermediates such as methanol and/or dimethyl ether and hydrocarbons as products such as in particular ethylene and propylene) are present in the reaction matrix at all times. In addition to the reaction kinetics, the corresponding proportion is determined in particular by the thermodynamic equilibrium position. In particular at the reactor outlet, the composition should increasingly approach this thermodynamic equilibrium.

Considering the conversion of carbon dioxide to propylene starting from a stoichiometric mixture, this includes the reactions according to equations (1) and (3) above. The diagram according to FIG. 2A illustrates the conversion X _eq in percent for the case that the reactions are successively brought to equilibrium, on the vertical axis compared to a pressure p in bar on the horizontal axis shown on the left and a temperature in G on the horizontal axis shown on the right . In the diagram according to FIG. 2B, on the other hand, the conversion X _eq for the case in which both reactions are brought into equilibrium simultaneously is illustrated with identical axes as in FIG. 2A.

By combining both steps (here the methanol synthesis combined with the conversion to propylene) in one reactor with a suitable bifunctional catalyst or a mixture of suitable catalysts for both reaction steps accordingly, there is a significantly higher yield than when the two reactions are carried out sequentially.

Overall, the present invention proposes a method in which carbon dioxide and / or carbon monoxide are reacted with hydrogen in a process gas stream that is fed to a reactor, at least in part in a first reaction step to form one or more oxygenates, the or in the Process gas stream pass over, and in which the one or more oxygenates in the process gas stream is or are converted at least in part in a second reaction step to form the one or more hydrocarbons, which pass into the process gas stream, the process gas stream flowing through in one flow direction a reactor assembly is performed. A “reactor arrangement” is to be understood as an arrangement that has one or more reactors and the components required for their operation as minimum equipment.

In the context of the present invention, the reactor arrangement comprises one or more reactors which has or have a first and a second reaction zone, the second reaction zone being arranged downstream of the first reaction zone in the direction of flow, and the first reaction zone and the second reaction zone being arranged in such a way are equipped with catalysts, that in the first reaction zone the first and the second reaction step are catalyzed, that in the second reaction zone the second reaction step is catalysed, and that in the second reaction zone the first reaction step does not occur or to a lesser extent than in the first reaction zone is catalyzed. A “lesser extent” is understood to mean, for example, a relative conversion of an amount of substance of less than 10%, in particular 5% and in particular 2%, of the amount of substance converted in the first reaction zone in the first reaction step.

In other words, within the scope of the invention, the first and second reaction zones can be located in one reactor of the reactor arrangement, or two reactors can be provided which have the two reaction zones in the arrangement mentioned one behind the other. Merely for reasons of simplification, “one” reactor is mentioned below. In the context of the present invention, there follows, in other words, a second reaction zone in which predominantly or exclusively one or more oxygenates such as methanol and/or dimethyl ether is or are being reacted, but not carbon dioxide, carbon monoxide and hydrogen, but which are further in the Process gas stream are included in a first reaction zone in which, in addition to the implementation of one or more oxygenates, the conversion of carbon dioxide, carbon monoxide and hydrogen to the oxygenates also takes place. In this way, the process gas in the second reaction zone is depleted of the one or more oxygenates, which also facilitates the subsequent processing, as explained in more detail below.

The first reaction zone can, in the present context, be equipped with one or more first catalysts, which catalyzes or catalyze the first reaction step, and with one or more second catalysts, which catalyzes or catalyzes the second reaction step, for example in the form of a physical mixture. Alternatively, it is also possible to equip the first reaction zone with one or more bifunctional catalysts which catalyze or catalyze the first and the second reaction step. In both cases the advantages according to the invention are achieved.

In contrast to the two-stage design, i.e. the sequential sequence of oxygenate synthesis and further conversion to hydrocarbons, a bifunctional catalyst without the use of the measures proposed according to the invention, or even the pure use of two catalysts simultaneously, ie in one catalyst bed, also has a disadvantage for the technical Use on. Since, as mentioned, complete conversion of carbon monoxide and carbon dioxide cannot be achieved in technically relevant systems, one or more oxygenates are continuously formed in accordance with the thermodynamic equilibrium by such a bifunctional catalyst or a corresponding mixture, which or the thus is or are present in significant amounts (at least in the percentage range) in the effluent of a respective reactor. The one or more oxygenates are converted together with the water of reaction into a condensate from which the condensate or condensates, in particular methanol, can only be separated off and put to use with comparatively great effort. So there is inevitably a undesired by-product that is hardly economically separable or usable. As a result, this by-product is usually fed into a wastewater treatment system with the condensate and is thus lost from the value chain. For example, methanol can be broken down by suitable bacteria in biological wastewater treatment, which in turn results in the emission of carbon dioxide. Although this degradation of methanol in biological sewage treatment plants is in principle technically possible without further ado, it means additional effort here (because of the capacity to be provided for the biological treatment). By using the present invention, a separation or subsequent waste water treatment is no longer necessary or a lower capacity is sufficient here, since the one or more oxygenates are reacted in the second reaction zone.

In other words, according to the invention, the content of oxygenate(s) at the reactor outlet can be effectively minimized and thus the process efficiency in the direction of the target products can be significantly increased. Other components such as carbon monoxide, carbon dioxide and hydrogen can then be separated from the target products and recycled relatively easily.

In a further embodiment of the invention, one or more further reaction zones containing suitable catalysts which in particular catalyze a water gas shift reaction and/or the formation of methanol and/or dimethyl ether as an intermediate can also be arranged upstream of the first reaction zone according to the invention. In these zones, the further conversion to hydrocarbons according to the above definition is not catalyzed or only to a “lesser extent” than in the first reaction zone.

In principle, various reactor types are suitable for carrying out the reaction with heterogeneous catalysts. Fixed-bed reactors, as described for example in [40] and [41], are particularly advantageous since they are structurally comparatively easy to implement. In particular, the reactor used in the context of the present invention is therefore designed as a fixed-bed reactor which has fixed catalyst beds in the first reaction zone and in the second reaction zone, which contain the respective catalysts as fixed-bed catalysts. The same applies if several reactors are used or in one corresponding reactor arrangement are included. A "catalyst bed" typically has a supported catalyst in a suitable support structure.

In the context of the present invention, in particular tube bundle reactors with a suitable cooling medium, in particular a molten salt, can be used. The cooling can take place in co-current or counter-current with the process gas flow, and different cooling/heating zones can also be provided within the scope of the invention, if required. The reaction zones provided according to the invention are formed by separate catalyst beds arranged in parallel in the reaction tubes, or such catalyst beds together form the reaction zones in each case. It goes without saying that when, in simplified terms, "a process gas stream" is passed through the reactor or a corresponding reactor arrangement, in the case of a tube bundle reactor this refers to a number of partial streams corresponding to the number of reaction tubes.

Adiabatic fixed-bed reactors are known, which can optionally also be designed in a multi-stage design with intermediate coolers. In addition, heated or cooled reactors, which are typically designed as tube bundle reactors, are known, in particular for strongly endothermic or exothermic reactions. In particular, systems with a phase change (e.g. water/steam or other evaporating liquids), thermal oils or, especially at higher temperatures, molten salts are used as the cooling/heating medium. The temperature control can take place in co-current or counter-current, and in more recent designs different cooling/heating zones are also provided in the design.

The use of multilayer catalyst beds or beds in a fixed bed reactor is also known. In order to increase the overall yield with only a minimal loss of commercial product selectivity, multilayer catalyst beds can be used in conventional processes, optionally with increasing activity along the direction of flow in the reactor.

For example, DE10 2005 004 926 A1 describes a catalyst system for catalytic gas-phase reactions which is characterized by increasing catalyst activity in the direction of flow. However, this one will Activity increase achieved exclusively by mixtures of different active catalysts, but which basically catalyze the same reaction. The production of phthalic anhydride, ethylene dichloride, cyclohexanone, maleic anhydride and acrylic acid is mentioned in particular as a method. A continuous gradient is expressly suggested and not the use of different defined zones.

EP 3 587383 A1, relating to oxidative dehydrogenation, also uses a reactor which has a plurality of reaction zones, each with a catalyst bed. The several reaction zones can be designed in particular as a layered structure made up of several catalyst beds or as reaction zones which are separate from one another and each have one catalyst bed. A configuration of corresponding reaction zones in the form of multilayer catalyst beds, which in this case form several catalyst beds, is also listed. The catalyst loading and/or catalyst activity is adjusted in particular by different degrees of dilution using inert material, but the active catalyst material in the different reaction zones is identical and therefore basically catalyzes the same reactions.

In the context of the present invention, the first reaction zone advantageously has a plurality of catalyst beds which are arranged one behind the other in the direction of flow and have a plurality of different catalysts or one catalyst with different activity. This can also relate to a bifunctional catalyst, as can be provided in the first reaction zone. Mixtures of catalysts in different mixing proportions can also be provided. In the process according to the invention, a plurality of catalyst-free inert zones are advantageously also formed in the direction of flow. These can be, for example, before the first and after the second reaction zone. Further inert beds can also be arranged between the reaction beds and/or individual catalyst beds in order, for example, to achieve better heat dissipation or temperature control.

In the context of the present invention, catalysts which are generally known for the respective reaction system can be considered without restriction. Reference is made to the above explanations, in particular in connection with Table 1. the The invention is characterized less by the types of catalysts used than by the reactions catalyzed by them and the order and specific type of arrangement of the catalysts used.

The process according to the invention can be carried out at a pressure level of 10 to 100 bar, in particular 12 to 50 bar, more particularly 15 to 35 bar, and a temperature level of 150 to 580°, in particular 200 to 450°, more particularly 250 to 400° will.

The process according to the invention is suitable for the reaction of carbon dioxide and carbon monoxide and gas streams with any mixtures of these two components. In this case, hydrogen is to be provided in a suitable stoichiometric amount in the reaction feed.

The index S _N , the so-called stoichiometric modulus, is helpful and common for determining the required proportion of hydrogen in corresponding reactions. It is determined from the mole fractions x of carbon monoxide, carbon dioxide and hydrogen as follows:

S _N = ( _XH2 - _xCO2 ) / (xCO + _xCO2 ) (5)

Equations 6 and 7 below describe the idealized synthesis of ethylene. Here, regardless of the actual ratio of carbon monoxide to carbon dioxide, S _N = 2 always applies.

2CO + _4H2C2H4 ₊ _2H2O ( ₆ )

_2CO2 ₊ _6H2C2H4 ₊ 4H2O ( ₇ )

The following equations 8 and 9 describe the idealized synthesis of propylene, in which S _N = 2 also always applies, regardless of the actual ratio of carbon monoxide to carbon dioxide.

3CO ₊ _6H2C3H6 ₊ _3H2O (8)

_3CO2 ₊ _9H2C3H6 ₊ _6H2O (9) In the case of ethylene and/or propylene as the target product, the proposed process therefore preferably uses a feed composition for which (under idealized consideration and without consideration of side reactions) at least S _N =2 applies. Due to side reactions, an adjustment is necessary in reality, so that the previously mentioned reaction equilibria are advantageous. On the other hand, a positive effect of an excess of hydrogen on the deactivation and coking behavior of the catalyst can also usually be determined.

An upper limit for S _N is also advantageous in order to limit the effort required to separate and recycle hydrogen and, on the other hand, to avoid an overreaction of olefins to form the corresponding paraffins ("hydrogenation").

In the context of the present invention, the process gas stream of the reactor arrangement used in the invention is therefore advantageously fed with a stoichiometric modulus of 1.5 to 10, in particular 2 to 4.

As mentioned several times, in the context of the present invention the one or more oxygenates are in particular methanol and/or dimethyl ether and the one or more hydrocarbons are in particular ethylene and propylene. In principle, however, the present invention is also suitable for other methods of carbon monoxide and/or carbon dioxide hydrogenation, i.e. in particular also the production of higher hydrocarbons having four or more carbon atoms.

In the context of the present invention, the process gas stream can also have other components, in particular methane and/or higher hydrocarbons, in addition to the components mentioned, hydrogen, carbon dioxide and/or carbon monoxide, when it enters the reactor arrangement.

After passing through the reactor arrangement, the hydrocarbons in particular can be separated off, it being possible for at least some of the remainder to be returned to the inlet of the reactor arrangement in order to maximize the overall yield of the process. The plant according to the invention for the production of one or more hydrocarbons, in particular ethylene and/or propylene, is set up to combine carbon dioxide and/or carbon monoxide with hydrogen in a process gas stream which is fed to a reactor arrangement, at least in part in a first reaction step to form one or converting a plurality of oxygenates which pass into the process gas stream, and converting the one or more oxygenates in the process gas stream at least in part in a second reaction step into the one or more hydrocarbons which pass into the process gas stream.

According to the invention, the plant is set up to guide the process gas stream through the reactor arrangement in a direction of flow, the reactor arrangement having one or more reactors which comprise or comprise a first reaction zone and a second reaction zone, the second reaction zone being downstream in the direction of flow first reaction zone is arranged, and wherein the first reaction zone and the second reaction zone are equipped with catalysts in such a way that the first and the second reaction step are catalyzed in the first reaction zone, that the second reaction step is catalyzed in the second reaction zone, and that in the second Reaction zone, the first reaction step is not catalyzed or to a lesser extent than in the first reaction zone.

For features and advantages of a corresponding system and its configurations, which can be set up in particular to carry out a method as explained above in different configurations, reference is expressly made to the above explanations with regard to the method according to the invention and its configurations.

Summarized again, the present invention achieves a particularly efficient conversion of carbon monoxide and/or carbon dioxide with hydrogen to products of value. In this case, the conversion or the yield is maximized compared to conventional processes. An integrated procedure is achieved without isolating the intermediate or the intermediates. Nevertheless, there is a minimization of intermediates such as methanol and/or dimethyl ether as (unused) by-products in the effluent. The process efficiency towards the desired target products (particularly ethylene and/or propylene) increases. No complex methanol recovery is required and the requirements for wastewater treatment (biology) are minimized. Overall, there is a reduction in construction and operating costs.

The invention will be explained below with reference to the accompanying drawings, which illustrate an embodiment of the invention and its advantages.

Brief description of the drawings

FIG. 1 shows a method according to an embodiment of the invention.

FIGS. 2A and 2B illustrate advantages of an embodiment of the invention over the prior art using conversion diagrams.

Detailed description of the drawings

In FIG. 1, a method according to a particularly preferred embodiment of the present invention is illustrated in the form of a schematic flowchart and denoted overall by 100. The following explanations relate to a system according to an embodiment of the invention in the same way.

In the process 100, carbon dioxide and/or carbon monoxide is reacted with hydrogen in a process gas stream 1, which is fed to a reactor 10, at least in part in a first reaction step to form one or more oxygenates, which pass into the process gas stream 1, and the one or more oxygenates in the process gas stream 1 is or are at least partly converted into one or more hydrocarbons in a second reaction step, which or which pass into the process gas stream 1 . As mentioned, instead of one reactor 10, an arrangement with several reactors can also be used within the scope of the invention.

As illustrated by a corresponding arrow, the process gas stream 1 is guided in a flow direction through the reactor 10, the reactor 10 having a first reaction zone 11 and a second reaction zone 12, the second Reaction zone 12 is arranged downstream of the first reaction zone 11 in the direction of flow, with the first reaction zone 11 in the example shown having one or more bifunctional catalysts that catalyze the first and second reaction step, and the second reaction zone 12 having one or more predominantly or exclusively the second reaction step having catalyzing catalysts. For further configurations, reference is made to the above explanations. Instead of the one or more bifunctional catalysts, it is also possible, for example, to use a mixture of a plurality of catalysts, as mentioned. Merely for the sake of simplicity, a “bifunctional” catalyst is described in the first reaction zone and a “monofunctional” catalyst in the second reaction zone in the description of the figures.

A fixed-bed reactor is used as reactor 10, which has a plurality of catalyst beds 11a, 11b, 11c in the first reaction zone 11, which contain the one or more bifunctional catalysts as fixed-bed catalyst or fixed-bed catalysts, and which has a catalyst bed in the second reaction zone 12 12a, which contains the one or more monofunctional catalysts as a fixed bed catalyst or fixed bed catalysts. Further zones 14 can be provided and equipped accordingly with a catalyst. Catalyst-free inert zones 13 are formed upstream of the first and downstream of the second reaction zone.

The diagrams shown in FIGS. 2A and 2B have already been explained above.

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Claims

23

Method (100) for producing one or more hydrocarbons, in which carbon dioxide and/or carbon monoxide is reacted with hydrogen in a process gas stream (1) which is fed to a reactor arrangement, at least in part in a first reaction step to form one or more oxygenates, which or which pass into the process gas stream (1), and in which the one or more oxygenates in the process gas stream (1) is or are at least partly converted into one or more hydrocarbons in a second reaction step, which or which into the process gas stream (1), characterized in that the process gas stream (1) is guided through the reactor arrangement in one direction of flow, the reactor arrangement having one or more reactors (10) which have a first reaction zone (11) and a second reaction zone (12 ) comprises or comprise, wherein the second reaction zone (12) in the flow direction is arranged after the first reaction zone (11), and wherein the first reaction zone (11) and the second reaction zone (12) are equipped with catalysts in such a way that in the first reaction zone (11) the first and the second reaction step are catalyzed, that in in the second reaction zone the second reaction step is catalyzed, and that in the second reaction zone (12) the first reaction step is not catalyzed or is catalyzed to a lesser extent than in the first reaction zone (11). Method (100) according to claim 1, wherein the first reaction zone (11) with one or more first catalysts, which or which catalyzes or catalyze the first reaction step, and with one or more second catalysts, which or which catalyzes or catalyzes the second reaction step , Is provided. Process (100) according to claim 1, in which the first reaction zone (11) is equipped with one or more bifunctional catalysts which catalyze or catalyze the first and the second reaction step.

4. Process (100) according to one of the preceding claims, in which fixed catalyst beds (11a, 11b, 11c, 12a) are used in each case in the first reaction zone (11) and in the second reaction zone (12).

5. The method (100) according to any one of the preceding claims, in which the reactor or reactors (10) is or are designed as a tube bundle reactor, which is or are cooled using a cooling medium that is conducted in cocurrent or countercurrent with the process gas stream will or will.

6. The method (100) according to claim 1, in which the first reaction zone (11) has catalyst beds (11a, 11b, 11c) arranged one behind the other in the flow direction and having a plurality of different catalysts or one catalyst with different activity.

7. The method (100) according to any one of the preceding claims, in which one or more catalyst-free inert zones (13) is or are formed.

8. The method (100) according to any one of the preceding claims, in which upstream of the first reaction zone (11) one or more further reaction zones is or are arranged, which contains or contain one or more catalysts, which or which at least one further reaction, in particular one Water gas shift reaction and/or the formation of methanol and/or dimethyl ether as an intermediate, catalyzes or catalyzes.

9. Method (100) according to one of the preceding claims, which is carried out at a pressure level of 10 to 100 bar and a temperature level of 150 to 580°C.

10. The method (100) as claimed in claim 1, in which the process gas stream (1) is fed to the reactor arrangement with a stoichiometry modulus of 1.5 to 10.

11 . A method (100) according to any one of the preceding claims, wherein the one or more oxygenates comprise methanol and/or dimethyl ether and wherein the one or more hydrocarbons comprise ethylene and/or propylene. Method (100) according to one of the preceding claims, in which the process gas stream (1) has further components, in particular methane and/or higher hydrocarbons. Method (100) according to one of the preceding claims, in which at least the hydrocarbons are at least partially separated from the process gas stream (1) after it has passed through the reactor arrangement, with a remainder of the process gas stream being at least partially returned to the inlet of the reactor arrangement. Plant for the production of a target compound, which is set up to convert hydrogen with carbon dioxide and/or carbon monoxide in a process gas stream (1), which is fed to a reactor arrangement, at least in part in a first reaction step to form one or more oxygenates, which or the pass over into the process gas stream (1), and convert the one or more oxygenates in the process gas stream (1) at least in part in a second reaction step into one or more hydrocarbons, which pass over into the process gas stream (1), characterized in that the plant is set up to guide the process gas stream (1) through the reactor arrangement in one direction of flow, the reactor arrangement having one or more reactors (10) which comprise a first reaction zone (11) and a second reaction zone (12) or comprise, wherein the second reaction zone (12) in the flow direction after the first Rea ction zone (11) is arranged, and wherein the first reaction zone (11) and the second reaction zone (12) are equipped with catalysts such that in the first reaction zone (11) the first and the second reaction step are catalyzed that in the second reaction zone the second reaction step is catalyzed, and that in the second reaction zone (12) the first reaction step is not catalyzed or to a lesser extent than in the first reaction zone (11). 26 Plant according to claim 14, which is set up for carrying out a method according to one of claims 1 to 13.