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
  • C07C5/42—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with a hydrogen acceptor
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
  • C07C2523/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper
  • C07C2523/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36
  • C07C2523/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • C07C2523/85—Chromium, molybdenum or tungsten
  • C07C2523/88—Molybdenum
  • C07C2523/881—Molybdenum and iron
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
  • C07C2523/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper
  • C07C2523/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36
  • C07C2523/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • C07C2523/85—Chromium, molybdenum or tungsten
  • C07C2523/88—Molybdenum
  • C07C2523/882—Molybdenum and cobalt
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
  • C07C2523/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper
  • C07C2523/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36
  • C07C2523/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • C07C2523/85—Chromium, molybdenum or tungsten
  • C07C2523/88—Molybdenum
  • C07C2523/883—Molybdenum and nickel

Definitions

• ABSTRACT A cyclical process is used to produce an olefinic hydrocarbon from parafiinic hydrocarbons.
• the feed is contacted with a molybdenum-containing metal compound, e. g., iron, cobalt, or nickel molybdate, the step being conducted for a sufficient time to dehydrogenate the paraffinic hydrocarbon and at least partially reduce the molybdate to molybdite.
• a molybdenum-containing metal compound e. g., iron, cobalt, or nickel molybdate
• the molybdenum compound (at least partially reduced to the state of molybdite) is reoxidized to the molybdate form-before it is contacted with additional paraffinic hydrocarbon, this reoxidation step being conducted by contacting the molybdite-containing compound with an oxygen-containing gas, essentially in the absence of paraffinic hydrocarbon.
• the first and second steps are repeated sequentially.
• the most economical way therefor consists of introducing air or oxygen for converting the hydrogen to water by combustion.
• a number of processes has been proposed in the case of preparing diolefins by controlled oxidation of olefins in the presence of catalysts, but the rare examples of production of olefins and diolefins by oxidizing paraffms are generally characterized by poor performances, mainly as the result of the degradation reactions involving a complete combustion due to the simultaneous presence, in the gaseous reaction medium of hydrocarbons and oxygen.
• This process offers, with respect to the known processes for oxidation of paraffins, numerous advantages, mainly a high selectivity and a high yield even at a moderate reaction temperature and relatively high pressure, Moreover, due to the operation in the absence of oxygen it is possible to avoid secondary reactions of degradation which otherwise occur when hydrocarbons and oxygen are present in the reaction medium, said reactions resulting in the formation of the carbon dioxide in non-negligible amounts thereby leading on the one hand to the loss of a portion of the paraffins and on the other hand to temperature increases which are detrimental to the oxidation reaction.
• paraffins which may be used according to the present invention are linear or branched paraffins containing from two to 10 and preferably from four to eight carbon atoms.
• the process may be carried out by means of any apparatus whereby is achieved an alternate contact of the molybdate with the gaseous phase containing the paraffms, either alone or diluted with an inert gas such as nitrogen, carbon dioxide or steam, and thereafter of the reduced molybdate with the oxygen-containing gaseous phase, the process being by no way limited to the use of any particular apparatus.
• an inert gas such as nitrogen, carbon dioxide or steam
• the reaction can be carried out in a reaction vessel operated under dynamic conditions; reactants, injected under a pressure between 0.1 and 2 atmospheres, are successively introduced into the reac tion vessel containing the slid mass in the form of grains, extrudates or powder, having a size elected, in accordance with the type of operation: in a fixed bed for example there can be used particles of a diameter for instance between 0.1 and 50 mm; in a fluid bed, smaller diameters will be preferred in order to obtain a good stability of the bed, for instance diameters between 0.01 and 0.2 mm; in a moving bed, i.e. when the solid catalyst is circulated in the reaction vessel, intermediate sizes of, f.i.,'0.05 to 0.5 mm can be used.
• the successive introduction of the reactants, paraffin and oxygen or air may be regulated by a system of automatically operated valves wherein each valve can be open only after the closure of the other valves.
• an intermediate supplemental injection of an inert gas nitrogen, steam, carbon dioxide, for example.
• the operating cycle will thus include the successive steps of l. Injecting paraffms on the molybdate, resulting in the production of olefins and diolefins and in at least a partial reduction of the molybdate to molybdite.
• the feeding system provides for sequential injections of gaseous reactants, paraffin, inert gas, oxygen or air for durations which are predetermined and adjustable in accordance with the experimental conditions.
• the velocity of the gaseous reactants is such that the flow rate, expressed in terms of the gas volume, under normal conditions of temperature and pressure, per volume of the contact mass and per hour, is, for example between 1,200 and 7,200 and preferably between 1,800 and 3,600 h.
• the time of injection of the paraffins may be, for instance, between and 1,800 seconds and preferably between and 180 seconds.
• the time of injection of oxygen may be for example between 2 and 60 and preferably between 10 and 30 seconds.
• the amount of inert gas to be injected for blowing off the reaction vessel depends on the volume of the installation and may accordingly vary within large limits; the time of injection can be made very short as compared to that of paraffin or oxygen, by use of a higher injection pressure. All the specific values of the pressures, flow rates and injection times are given only for illustrative purposes. 1n fact they are dependent on numerous factors and must generally be such as to provide preferably an equilibrium between the reaction of reduction of the molybdate during the stage of oxidizing paraffins and the reaction of oxidation of the molybdite when the same is contacted with an oxygen containing gas. According to the case, it may be of interest to use different flow rates for the paraffms and the oxygen, for example an oxygen flow rate higher than the paraffins flow rate.
• the temperature of the reactions may be advantageously between 400 and 800 C., preferably between 450 and 550 C., the pressure being between 0.5 and 20 kglcm
• the following non-limitative examples are given for illustrative purposes. In all of the examples there has been used a molybdenum and cobalt compound prepared in the following manner:
• the resulting precipitate is then filtered and dried in an oven at 1 10 C.
• the solid according to its designed conditions of use, is then crushed or extruded to the desired grain size.
• the solid is thereafter calcinated, either under an oxidizing atmosphere (0 air) in order to obtain the solid at its higher oxidation state in the form of cobalt molybdate CoMoO.,, or under a reducing atmosphere (N H C.,H so as to obtain the solid at its lower oxidation state in the form of cobalt molybdite Co Mo O together with C00.
• This calcination is conducted in both cases under identical temperature and pressure conditions, generally at a temperature between 300 and 800 C., preferably between 400 and 600 C., and under a pressure between 0.5 and 20 kg/cm
• EXAMPLE 1 There are used 10 g of the solid prepared as hereabove described with calcination under oxidizing atmosphere, in a tubular reactor operated under dynamic working conditions with successive introduction of the reactants as described before.
• the solid in the form of grains having a diameter of 0.3 to 0.4 mm, is used in a fixed bed.
• the reaction temperature is 500 C., the pressure 2 kg/cm and the spatial velocity 3,000 h".
• EXAMPLE 2 There are used the same conditions as in example 1 except for the injection time of each reactant.
• the injection time is 5 mn for n butane, 10 sec. for nitrogen, 50 sec. for oxygen and 10 sec. for the final nitrogen injection.
• the temperature and pressure conditions are the same as in example 1, the injection time of n-butane being brought to 15 mn.
• the spatial velocity of oxygen is brought to 3, 600 h, the injection time of oxygen being 1 mn.
• the cycle duration is thus 16 nm 20 sec.
• EXAMPLE 5 There are used 10 g of solid prepared as hereabove stated, with calcination under oxidizing atmosphere, the reaction temperature being 550 C., the pressure 2 kg/cm and the spatial velocity 3,000 h for n-butane and oxygen.
• the feed consists of 2-methylbutane which is injected under conditions identical to those of example 1.
• the reaction temperature is 500 C. and the pressure 2 kg/cm
• the spatial velocity is 3,000 h".
• the following results have been obtained C 20 i-nmulene isoprene isoprene hourly yield 0.5 kg/kg of solid.
• Example 6 is repeated but with a feed consisting of 2- methylbutane.
• the results obtained have been as follows C i-amulenc 21 isoprene isoprene hourly yield 1 1.13 kg/kg of solid.
• EXAMPLE 9 Another method of reaction between the solid and the reactants has been used in this example. It consists of circulating the solid between two reactors one of which is fed with n-butane and the other with oxygen, the solid being in the form of a powder with a grain size between 0.05 and 0.15 mm. With a reaction temperature of 500 C., a spatial velocity of 3,000 h and a pressure of 2 kg/cm the following results have been obtained C 25 Sam, 46 S04E15 48 The butadiene hourly yield is 0.65 kg/kg of solid EXAMPLE 10 There has been prepared a solid cobalt molybdate" deposited on an alumina carrier.
• the preparation method is as follows there is prepared a mixture of solutions of ammonium paramolybdate and cobalt nitrate identical to that described above, and to the solution are added alumina grains whose textural features are so selected as to provide absorption of the solution by alumina. This results in a solid wherein cobalt molybdate represents percent by weight of the mixture thereof with alumina.
• the calcination conditions are the same as in example 1.
• EXAMPLE 1 1 This example is given for comparison purpose. There are used 10 g of a solid prepared in the manner described in example 1, in a conventional tubular reactor operated under dynamic working conditions, with the solid in a powder form (grains diameter between 0.1 and0.2 mm) arranged in a fixed bed.
• the feed subjected to oxidation is a mixture containing 10 percent by volume of n-butane, 10 percent by volume of oxygen and ercent b golume of nitrogen,
• the reacion tempera ure 1s 0 C. and the spatial velocity 3,600 h.
• reaction temperature is between 400 and 800 C.
• a process according to claim 1 comprising al ternate injections, on the molybdenum compound in fixed bed, of the paraffinic hydrocarbon feed and the oxygen containing gas.
• a process as defined by claim 4 further comprising the intermediate step of blowing off the catalyst with an inert gas after the first step is completed but before the second step commences.
• a process as defined by claim 4 further comprising the intermediate step of blowing off the oxidized catalyst with an inert gas after the second step is completed but before the first step if repeated.
• a process as defined by claim 10 further comprising the intermediate step of blowing off the oxidized catalyst with an inert gas after the second step is completed but before the first step is repeated.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)

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Cited By (2)

Citations (6)

• 1968
  • 1968-10-28 FR FR171682A patent/FR1600465A/fr not_active Expired
• 1969
  • 1969-10-16 BE BE740349D patent/BE740349A/xx unknown
  • 1969-10-21 US US868205A patent/US3692860A/en not_active Expired - Lifetime
  • 1969-10-22 GB GB51810/69A patent/GB1240217A/en not_active Expired
  • 1969-10-24 DE DE19691953564 patent/DE1953564A1/de active Pending
  • 1969-10-24 ES ES372839A patent/ES372839A1/es not_active Expired
  • 1969-10-28 NL NL6916226A patent/NL6916226A/xx unknown

Patent Citations (6)

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