Reactor system for propane dehydrogenation

Abstract

Reactor system for propane dehydrogenation, characterized in that the reactor system has at least two reactor groups for propane dehydrogenation, of which at least one reactor group (7) has at least one electric reactor for propane dehydrogenation.

Description

[0001] The invention relates to a reactor system for propane dehydrogenation.

[0002] Propylene (propene) is conventionally produced primarily through steam cracking of hydrocarbon feedstocks and other conversion processes during refinery operations. In these cases, propylene is a byproduct obtained in smaller quantities. Due to the increasing demand for propylene, particularly for polypropylene, propane dehydrogenation is also being used.

[0003] Propane dehydrogenation (PDH) is a catalytic process that describes the production of propylene by the elimination of hydrogen from propane. Propane dehydrogenation is an endothermic equilibrium reaction. The maximum possible yield is limited by the chemical equilibrium. Higher temperatures and lower pressures lead to higher propylene yields. Hydrogen is released as a valuable byproduct in this process.

[0004] The present task is to propose a reactor system for propane dehydrogenation that reduces coke formation and the effort required for catalyst regeneration, while also improving economic efficiency.

[0005] The problem is solved by a reactor system with the features of the protection claim, the embodiments of which are explained below.

[0006] A reactor system comprises one or more reactor groups, each of which in turn contains one or more reactors. A reactor group typically operates according to only one reactor technology. A reactor group is characterized by the fact that all reactors within it operate in the same mode during steady-state operation. Thus, a reactor group is either operating in propane dehydrogenation mode or in regeneration mode. However, during start-up or shutdown of the reactor system, different operating modes may prevail within a reactor group.

[0007] According to the invention, the reactor system comprises at least two reactor groups for propane dehydrogenation, wherein at least one reactor group comprises at least one electric reactor for propane dehydrogenation. Preferably, the reactor system comprises at least one electric reactor group for propane dehydrogenation.

[0008] For the dehydrogenation of propane to propylene, reactors are used that have combustion chambers heated by burners, through which several reaction tubes are routed. The reaction tubes, which carry the reaction mixture, are heated externally by the burners. The reaction tubes contain a catalyst on a suitable support. Suitable catalysts are described, for example, in Bölt, H., "Dehydrogenation of Propane / Butane," Linde Reports from Technology and Science 66 / 1991. The propane to be dehydrogenated is passed through the reaction tubes together with steam, so-called process steam. Preheating using waste heat typically takes place beforehand. A gas mixture extracted from the reactor or the corresponding reaction tubes is then fed into a suitable product processing system.

[0009] Propane dehydrogenation is described, for example, in the article “Propene” in Ullmann's Encyclopedia of Industrial Chemistry, online edition 16 September 2013, DOI: 10.1002 / 14356007.a22_211.pub3, in particular section 3.3.1, “Propane Dehydrogenation”.

[0010] The following are mentioned as further publications on propane dehydrogenation: H. Zimmermann and H. Bölt: Linde / BASF Propane Dehydrogenation Process. In Proceedings of the DGMK / SCI Conference “Oxidation and Functionalization: Classical and Alternative Routes and Sources”, 2005. KJ Caspary, H Gehrke, M Heinritz-Adrian, and M Schwefer. Dehydrogenation of alkanes. In Handbook of Heterogeneous Catalysis, volume 7, 2nd ed., 2008, ISBN: 978-3-527-31241-2. JA Moulijn, M. Makkee, and AE van Diepen. Chemical Process Technology. Wiley, 2013, ISBN: 9781299449459. J. J. H. B. Sattler, J. Ruiz-Martinez, E. Santillan-Jimenez, and B. M. Weckhuysen. Catalytic dehydrogenation of light alkanes on metals and metal oxides. Chemical Reviews, 114(20):10613-10653, 2014. J. C. Bricker, Jan D.-Y., and J. M. Foresman. Dehydrogenation Catalyst Composition, United States Patent 4,914,075, assigned to UOP, 1988. D. Sanfilippo, F. Buonomo, G. Fusco, I. Miracca, and G. R Kotelnikov. Paraffins activation through fluidized bed dehydrogenation: the answer to light olefins demand increase. In Natural Gas Conversion V - Proceedings of the 5th International Natural Gas Conversion Symposium, volume 119, pages 919 - 924, 1998. J. Gregor and D. Wei. Uop oleflex process for light olefin production. In Handbook of petroleum refining processes, 2003, ISBN: 0-07-139109-6.

[0011] Typische Reaktionsbedingungen für die Propandehydreirung sind Temperaturen von 500-700°C und Drücke von 1 bis 3 bar(a).

[0012] However, during propane dehydrogenation, coke is deposited on the catalyst material as an undesirable byproduct. Therefore, the catalyst must be regularly cleaned of coke and regenerated in several steps.

[0013] Various reactor technologies are used in propane dehydrogenation, and the regeneration process also differs: In moving-bed reactors (such as the UOP Oleflex), the reaction mixture is passed through several adiabatic fixed beds in series, with heat input via fired intermediate heaters before each reactor bed. The catalyst material is continuously circulated through the reactor beds and, after passing through the last bed, is regenerated in a separate regeneration system.

[0014] In fluidized bed reactors (known, for example, as Snamprogetti-Yarsintez), energy is introduced by the still hot catalyst particles after the coke layer has burned off in the regeneration unit.

[0015] In adiabatic catalyst beds in semi-batch operation (known, for example, as Catofin), energy input occurs through cyclical combustion of the coke layer on the catalyst.

[0016] In a reformer, also called a "direct-fired reactor" (known, for example, as the Uhde STAR), there are reformer tubes filled with PDH catalyst in which the reaction takes place. Several reformer units are operated in parallel. To regenerate the catalyst, one or more reformers are operated in regeneration mode.

[0017] However, the reactor technologies used for propane dehydrogenation have disadvantages. For example, reformers and moving-bed reactors use fossil fuels for their burners, resulting in CO2 emissions. Fluidized-bed reactors and semi-batch adiabatic catalyst beds release CO2 emissions during regeneration through the combustion of coke on the catalyst, which occurs using fossil fuels.

[0018] Another disadvantage is the imprecise reaction control of the PDH reaction: the reactors must be operated within a very narrow temperature range to achieve economical conversions and selectivities. Temperatures that are too low lead to low conversions in the reactor, while temperatures that are too high lead to increased coke formation. Increased coke formation, in turn, leads to a lower propylene yield and requires more extensive catalyst regeneration, with additional CO2 emissions resulting from the combustion of the coke.

[0019] In addition to the complex regeneration process, the spatially and / or temporally disadvantageous temperature conditions of existing technologies are also compensated for by low absolute pressures or low partial pressures achieved through the use of water or hydrogen as a dilution medium, which negatively impacts the economic viability of the process.

[0020] Preferably, the electric reactor used according to the invention for propane dehydrogenation belongs to an electric reactor group for propane dehydrogenation. Ceramic channels with heating wire and a catalyst coating, in which the reaction takes place, are particularly suitable for the electric reactor. For example, reactors from the manufacturer SYPOX are suitable. Such reactors allow for an advantageous, compact design with large surface areas and close proximity of the heat source and catalyst. Furthermore, the temperature control can be optimized particularly effectively in such electric reactors, which reduces coke formation. This results in fewer regeneration cycles being necessary. Since less coke needs to be burned off, CO2 emissions are reduced.

[0021] According to the invention, fired reactors, in particular, can be replaced by electric reactors. Advantageously, an entire reactor group is replaced. This reduces CO2 emissions, provided that renewable electricity is used. The flexible use of electricity for the electric reactor group and fuel for the fired reactor group also enables load adjustment depending on the availability of electricity and fuel, or their current prices. Furthermore, it becomes possible to purchase negative control energy from the power grid to compensate for excess power in the grid.

[0022] Electric reactors increase plant flexibility because they can be started up and shut down quickly. This is also an advantage. Drawings

[0023] Aspects proposed within the scope of this disclosure are explained in more detail with reference to the accompanying drawing. These show Fig. 1 a known reactor system with fired reactor groups and the Fig. 3 to 5 reactor systems according to the invention.

[0024] A well-known reactor system, such as Fig. Figure 1 shows fired reactor groups with fired reactors. A feed stream 101, containing propane, is fed into a feedstock preparation unit 1. From this unit, a processed feed stream containing propane, hydrogen, and process steam is fed into the fired reactor groups 3 and 4. Propane dehydrogenation takes place in reactor groups 3 and 4. The propylene-containing product streams from the propane dehydrogenation are fed into the product preparation unit 2. The following product streams are discharged from product preparation unit 2: the hydrogen product 102, the propylene product 103, and the C4plus product 104. The C2minus product 105 leaves product preparation unit 2 and is fed as fuel gas 106 into reactor groups 3, 4, 5, and 6. Catalyst regeneration takes place in reactor groups 5 and 6, for which the fuel gas 106 is required. From product preparation 2, process steam 107, propane 108 and hydrogen 109 are recycled to the input preparation 1.In the described reactor system, a supply of external heating gas 106 is necessary in order to operate the reactor system.

[0025] The Fig. Figures 2 to 5 show embodiments according to the invention. The reference numerals of the Fig. 2 to 5 correspond to those of the Fig. 1. Further details can also be found in the list of reference symbols at the end of the description.

[0026] Fig. Figure 2 shows an embodiment according to the invention in which the reactor groups are arranged in parallel operation. The propane-containing feedstock 101 is fed into the feedstock preparation unit 1. The processed feedstock, containing propane, hydrogen, and the process mixture, is fed into the electrical reactor group 7 and the fired reactor group 4. The fuel gas 106 is additionally fed into the fired reactor group 4. The propylene-containing product streams from reactor groups 7 and 4 are fed into the product preparation unit 2. The following product streams are discharged from the product preparation unit 2: the hydrogen product 102, the propylene product 103, and the C4plus product 104. Process steam 107, propane 108, and hydrogen 109 are recycled from the product preparation unit 2 into the feedstock preparation unit 1. The C2minus product 105 leaves the product processing unit 2 and is fed as heating gas 106 into reactor groups 4 and 6.Reactor group 6 is undergoing regeneration, and the fuel gas 106 is required for coke combustion. Electrical reactor group 8 is also in regeneration mode. The energy required for regeneration is supplied electrically to electrical reactor group 8, and only the coke combustion releases carbon dioxide. Due to the electrical reactor groups, an external supply of fuel gas is generally not necessary; the C2minus product is sufficient as fuel gas.

[0027] Fig. Figure 3 shows an embodiment according to the invention in which a fired reactor group 4 and an electric reactor group 7 are connected in series. Reactor groups 6 and 8 are in regeneration mode. A hot gas supply 106 is required for the fired reactor group 4 and for the fired reactor group 6, which is in regeneration mode. No hot gas supply is required for the electric reactor groups 7 and 8. For a further description and the advantages of this embodiment, reference is made to the preceding explanations. Fig. Reference is made to Figure 2. Advantageously, in this configuration, the electrical reactor group 7 can be operated at a low temperature to protect the catalyst, since further conversion can take place at a high temperature in the series-connected fired reactor group 4. In a particularly preferred case, the temperature in the electrical reactor group can be selected such that this reactor group only needs to be regenerated very rarely, or that regeneration is not necessary at all during the entire lifetime of the catalyst. Due to the series connection, the fired reactor group 4 can be designed with a significantly lower power output than without this series connection.

[0028] The embodiment according to the invention Fig. 4 differs from that of the Fig. 3. The order of the reactor groups is determined by the arrangement. Here, the fired reactor group 3 is followed by the electric reactor group 7. In many cases, coke formation in an electric reactor group can be significantly reduced compared to fired reactor groups, even at high temperatures, by optimizing temperature control. The fired reactor group 3 operates at low temperatures. This allows for optimal use of the reactor system and minimizes reactor group failures due to regeneration.

[0029] Fig. Figure 5 shows an embodiment according to the invention with four electric reactor groups 7, 9, 8 and 10, wherein electric reactor groups 7 and 9 generate a product stream, while electric reactor groups 8 and 10 are undergoing regeneration. If only electric reactor groups are used, the C₂ minus product 10⁵ is discharged as the product, since no fuel gas is required. Carbon dioxide emissions occur exclusively through the combustion of coke.

[0030] By optimizing the catalyst, it can advantageously be achieved that no regeneration is necessary within the catalyst's lifetime. This is in Fig. Figure 6 shows where the two reactor groups 7 and 9 are in operation while no reactor group is in regeneration.

[0031] In addition to the reactor systems shown in the figures, other reactor arrangements are possible. In particular, reactor systems with series connections of reactor groups are possible, which are not shown.

[0032] The meaning of the reference symbols is as follows: 1. Reprocessing of the active substance 2 Product processing 3 Fired reactor group in propane dehydrogenation operating mode 4 Fired reactor group in propane dehydrogenation operating mode 5 fired reactor group in regeneration operating mode 6 fired reactor group in regeneration operating mode 7 Electrical reactor group in propane dehydrogenation operating mode 8 Electrical reactor group in regeneration operating mode 9 Electrical reactor group in propane dehydrogenation operating mode 10 Electrical reactor group in regeneration operating mode 101 Insert containing propane 102 Hydrogen product 103 Propylene product 104 C4plus product 105 C2minus product 106 Heating gas 107 Recirculated process steam 108 Recycled propane 109 Recycled hydrogen QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 4,914,075

[0010] Cited non-patent literature

[0000] Bölt, H., “Dehydration of propane / butane”, Linde Reports from Technology and Science 66 / 1991

[0008] Propene“ in Ullmann's Encyclopedia of Industrial Chemistry, Onlineausgabe 16. September 2013, DOI: 10.1002 / 14356007.a22_211.pub3

[0009] H. Zimmermann and H. Bölt: Linde / BASF Propane Dehydrogenation Process. In Proceedings of the DGMK / SCI-Conference „Oxidation and Functionalization: Classical and Alternative Routes and Sources“, 2005

[0010] K. J. Caspary, H. Gehrke, M. Heinritz-Adrian, and M. Schwefer. Dehydrogenation of alkanes. In Handbook of Heterogeneous Catalysis, volume 7, 2nd ed., 2008, ISBN: 978-3-527-31241-2

[0010] J. A. Moulijn, M. Makkee, and A. E. van Diepen. Chemical Process Technology. Wiley, 2013, ISBN: 9781299449459

[0010] J. J. H. B. Sattler, J. Ruiz-Martinez, E. Santillan-Jimenez, and B. M. Weckhuysen. Catalytic dehydrogenation of light alkanes on metals and metal oxides. Chemical Reviews, 114(20):10613-10653, 2014

[0010] J. C. Bricker, Jan D.-Y., and J. M. Foresman. Dehydrogenation Catalyst Composition, United States

[0010] D. Sanfilippo, F. Buonomo, G. Fusco, I. Miracca, and G. R Kotelnikov. Paraffins activation through fluidized bed dehydrogenation: the answer to light olefins demand increase. In Natural Gas Conversion V - Proceedings of the 5th International Natural Gas Conversion Symposium, volume 119, pages 919 - 924, 1998

[0010] J. Gregor and D. Wei. Uop oleflex process for light olefin production. In Handbook of petroleum refining processes, 2003, ISBN: 0-07-139109-6

[0010]

Claims

[1] Propane dehydrogenation reactor system, characterized by that the reactor system has at least two reactor groups for propane dehydrogenation, of which at least one reactor group (7) has at least one electric reactor for propane dehydrogenation. [2] Reactor system according to claim 1, characterized by , that at least one of the at least two reactor groups is an electric reactor group (7) for propane dehydrogenation. [3] Reactor system according to claim 2, characterized by , that the reactor system consists exclusively of electrical reactor groups (7, 9). [4] Reactor system according to claim 2, characterized in that the reactor system comprises at least one electrical reactor group (7) and at least one fired reactor group (4).

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