Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
  • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
  • C07C5/373—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen with simultaneous isomerisation
  • C07C5/393—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen with simultaneous isomerisation with cyclisation to an aromatic six-membered ring, e.g. dehydrogenation of n-hexane to benzene
  • C07C5/41—Catalytic processes
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
  • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
  • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
  • C07C5/333—Catalytic processes
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
  • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
  • C07C5/373—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen with simultaneous isomerisation
  • C07C5/393—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen with simultaneous isomerisation with cyclisation to an aromatic six-membered ring, e.g. dehydrogenation of n-hexane to benzene
  • C07C5/41—Catalytic processes
  • C07C5/415—Catalytic processes with metals

Definitions

• the invention relates to a process for the dehydrogenation of alkanes with homogenization of the product composition, wherein an alkane is passed over a suitable catalyst, whereby a gas stream is formed, which is an alkene, hydrogen and contains an unreacted alkane. Since the dehydrogenation of alkanes belongs to the group of reversible equilibrium reactions, the chemical equilibrium sets in under ideal catalyst conditions during the reaction after a certain residence time. The homogenization of the product composition or a constant proportion of alkene, alkane and hydrogen in the product gas is achieved by influencing the chemical equilibrium by means of process parameters in the desired direction. The dehydrogenation of alkanes takes place on a suitable catalyst. Over time, the activity of the catalyst decreases under the same reaction conditions. This causes the product composition at the reactor outlet to change permanently over a production cycle if the process parameters remain unchanged. Due to the constantly changing product composition, there may be disruptions in subsequent system components. For example, the rectification columns are sensitive to concentration variations in the feedstream.
• US 5243122 A describes a process for an allothermal reformer for the dehydrogenation of light alkanes, wherein the temperature of the catalyst bed is controlled during the reaction and slowly raised so that the composition of the reactor effluent remains the same during the reaction. By doing so, the slowing down of the activity of the catalyst is retarded, so that the composition of the product stream and in particular the alkene / alkane ratio contained therein remain the same during operation.
• the thermal control of the reaction is controlled by a special valve control of the fuel gas supply.
• the reformers are arranged in parallel, except the temperature, the other factors were not treated.
• BESTATIGUNGSKOPIE can be passed over the catalyst. This gas oxidizes the carbonaceous deposits so that the catalyst is exposed and the reaction can begin anew.
• the invention is therefore based on the problem of developing a process for the dehydrogenation of alkanes, with which the product composition at the reactor outlet remains constant over the entire operating time.
• a gaseous alkane-containing stream is passed in a continuous mode through a catalyst bed in several reactors of adiabatic, allothermic or isothermal type or combinations thereof, thereby creating a gas stream, which is an alkene, hydrogen and unreacted Contains alkane, and that
• At least one of the process parameters temperature, pressure or steam-hydrocarbon ratio is detected at one or more points on at least one of the reactors in the form of measured values
• At least one of the process parameters is specifically influenced, so that the composition of the product gas at the output of at least one reactor remains constant over the service life.
• Measured values of temperature, pressure or steam / hydrocarbon ratio can be determined at one or more points of a reactor, then the process parameters can be purposefully controlled and influenced by means of control devices so that the composition of the product gas at the end of the reactor system can be monitored. remains constant over the service life.
• the process parameters temperature, pressure and steam-hydrocarbon ratio can be influenced in a targeted manner.
• the temperature in at least one of the reactors can be regulated.
• the pressure in the reactor via the removal of the product gas can be controlled by means of a control valve.
• the steam Hydrocarbon ratio in the reactor is determined by the addition amounts of steam and gaseous hydrocarbon, this action being preferred in the first of the reactors.
• an analyzer for measuring the composition of the product gas is used.
• the analyzer may be, for example, a gas chromatograph.
• the composition of the product gas is determined with the aid of the analyzer.
• the process parameters both individually and in combination, can be influenced in such a way that the desired homogenization of the composition of the product gas can be achieved.
• the same can also be obtained by specifying a time-varying function, for example a ramp function, by a process control system.
• the use of the inventive method for the production of alkenes from alkanes is claimed, in particular the use of the method for the dehydrogenation of propane to propene, of n-butane to / i-butenes and butadiene, from / so Butane to / so-butene, or mixtures thereof and the dehydrocyclization of alkanes to aromatics.
• any alkane or hydrocarbon that is dehydrogenatable by a prior art dehydrogenation process can be dehydrogenated.
• an allothermal reactor for the dehydrogenation of propane to propene is considered as an embodiment in order to represent the process according to the invention.
• the reactor is operated with the following process-technical values: inlet temperature: 510 ° C., temperature difference between inlet and outlet ⁇ T: 75K, outlet pressure p: 6.0 bar, molar steam-hydrocarbon ratio STHC: 3.5.
• Example 1 As shown in Fig. 1, the yield of propene decreases from 26.7% to 26.1% without adjusting the process parameters.
• Example 2 As shown in Fig. 2, by raising the temperature difference ⁇ T over the cycle, the yield of propene is kept constant at 26.7%. All other parameters remain unchanged compared to example 1.
• Example 3 As shown in Fig. 3, by lowering the discharge pressure p over the cycle, the yield of propene is kept constant at 26.7%. All other parameters remain unchanged compared to example 1.
• Example 4 As shown in Fig. 4, by raising the steam-hydrocarbon ratio (STHC) over the cycle, the yield of propene is kept constant at 26.7%. All other parameters remain unchanged compared to example 1.
• STHC steam-hydrocarbon ratio
• Example 5 As shown in FIG. 5, in this example the pressure is lowered constantly over the cycle time by 0.05 bar / h, and at the same time the temperature difference ⁇ T is slightly increased in order to obtain a uniform yield of propene.
• a one-sided reduction of the outlet pressure p over time (as in example 3) is often not possible at will, because the subsequent process step e.g. Raw gas compression requires a certain inlet pressure. Therefore, it makes sense to simultaneously influence several process parameters in order to achieve the desired homogenization of the composition of the product gas.
• Fig. 6 A device with allothermic and adiabatic reactor connected in series with a temperature control system.
• Fig. 7 A device with allothermal and adiabatic reactor connected in series with a temperature control system and a pressure control system.
• Fig. 8 A device with adiabatic reactors connected in series with temperature and pressure control system by means of a process control system.
• FIG. 6 shows a device comprising two reactors connected in series almuth (1) and adiabatic (2) with oxygen supply (3).
• the reaction gas (4) is fed into the allothermal reactor (1).
• the heating takes place via the burners (5) which are operated with a fuel gas (6) and an oxygen-containing gas (7).
• a closed pipe system (8) is provided, in which a catalyst is located and the reaction takes place.
• a temperature measuring device (10) and an analyzer (11) are connected.
• the fuel gas supply is controlled via the temperature measuring device (10) and the electrical control lines (10a) so that the measured values on the analyzer (11) always indicate the desired same proportion of alkene in the product gas (9).
• the product gas (9) from the reactor system (1) is then mixed with an oxygen-containing gas (3) and fed into the adiabatic reactor (2).
• this reactor there is also a closed dehydrogenation and hydrogen oxidation (12) piping system which contains a catalyst and where the hydrogen oxidation and further dehydrogenation takes place.
• a temperature measuring device (13) and an analyzer (14) At the output of the second reactor is also a temperature measuring device (13) and an analyzer (14).
• the oxygen supply is controlled via the temperature measuring device (13) and the electrical control lines (13a) so that the measured values on the analyzer (14) always indicate the desired same proportion of alkene in the product gas (15).
• Fig. 7 shows a device which also consists of a first allothermally operated reactor (1) and a second adiabatically operated reactor (2) with oxygen supply (3).
• the temperature is measured at the outlet of the first reaction system (9) by a temperature measuring device (10), and controlled in dependence on the fuel gas and oxygen supply (6,7) via electrical measuring signals (10a). In this way, a constant temperature can be set in the first reaction system.
• the product composition is controlled only at the outlet of the second reaction system (15). This is done via an analyzer (17) at the output of the second reaction system, which measures the pressure via a pressure-holding valve (16) on the reactor of the second reaction system (2) and forwards them via electrical control lines (16a, 17a) to a process control system (18).
• the temperature of the reactor (2) is controlled via the electrical control line (13a) and the oxygen addition (3).
• the process control system (18) calculates the required settings for the pressure and regulates via the electrical measuring signals (17a) and the pressure-maintaining valve (16) at the outlet of the reactor system so that always the same composition of the product gas (15) at the outlet of the second reactor (2) is obtained.
• Fig. 8 shows an apparatus of 3 series-connected adiabatic reactors (19, 2a, 2b) with oxygen supply (3a, 3b).
• the reaction in the first reactor (19) is adiabatic, so as to obtain a constantly changing product composition at the outlet of the reaction system (9).
• a selective hydrogen oxidation is carried out.
• a temperature measuring device (20) is mounted, this controls the reactor (2a) via the electrical measuring lines (20a) and the oxygen addition (3a).
• the electrical control lines (18a) the measured values of the temperature measuring device (20) are forwarded to a process control system (18).
• a homogenization of the composition of the product gas takes place at the outlet of the reactor (2a).
• a temperature measuring device (21) is likewise arranged, which regulates the attached reactor via the electrical control lines (21b) and the oxygen addition (3a).
• the temperature device (21) transmits the measured values to the process control system (18) via the electrical control line (21a). This results in a desired uniform composition of the product gas at the outlet of the third reaction system (22).

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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• 2009
  • 2009-07-22 DE DE102009034464A patent/DE102009034464A1/de not_active Ceased
• 2010
  • 2010-07-16 WO PCT/EP2010/004348 patent/WO2011009570A1/de active Application Filing
  • 2010-07-16 MY MYPI2012000246A patent/MY172617A/en unknown
  • 2010-07-16 US US13/386,588 patent/US20120197054A1/en not_active Abandoned
  • 2010-07-16 BR BR112012001215A patent/BR112012001215A2/pt not_active IP Right Cessation
  • 2010-07-16 EP EP10754857A patent/EP2456739A1/de not_active Withdrawn
  • 2010-07-16 KR KR20127004433A patent/KR20120099368A/ko not_active Application Discontinuation
  • 2010-07-16 MX MX2012000935A patent/MX2012000935A/es not_active Application Discontinuation
  • 2010-07-16 JP JP2012520940A patent/JP2012533583A/ja active Pending
  • 2010-07-16 RU RU2012105068/04A patent/RU2556010C2/ru not_active IP Right Cessation
  • 2010-07-16 CA CA2768874A patent/CA2768874A1/en not_active Abandoned
  • 2010-07-16 IN IN1598DEN2012 patent/IN2012DN01598A/en unknown
  • 2010-07-16 CN CN201080032742.2A patent/CN102471187B/zh not_active Expired - Fee Related
  • 2010-07-20 AR ARP100102643 patent/AR080272A1/es unknown
• 2012
  • 2012-01-18 EG EG2012010102A patent/EG27148A/xx active
  • 2012-02-21 ZA ZA2012/01280A patent/ZA201201280B/en unknown

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