Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C4/00—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms
  • C07C4/08—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by splitting-off an aliphatic or cycloaliphatic part from the molecule
  • C07C4/10—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by splitting-off an aliphatic or cycloaliphatic part from the molecule from acyclic hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C2531/00—Catalysts comprising hydrides, coordination complexes or organic compounds
  • C07C2531/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides

Definitions

• This invention relates to a promoted cracking process for certain olefins. More specifically it relates to a method of improving the cracking of certain olefins. Most specifically it relates to methods of improving the efliciency of cracking of certain olefin to form specific diolefins and parafiinic hydrocarbons or to form certain other specific olefins.
• olefins may be thermally decomposed or cracked by subjecting them to elevated temperatures, for instance olefins which have in their molecular make-up a carbon-carbon bond which is in a position beta to the double bond will under proper conditions of heat, time and pressure undergo a scission of the carbon-carbon bond in the position beta to the double bond.
• cracking, decomposing, cracked, or decomposed as employed throughout this specification and claims is meant that the olefin molecule splits into two or more fragments at the carbon-carbon bond which is in a position beta to the double bond. This will be explained in more detail later.
• the thermal decomposition or cracking of olefins is usually conducted in a closed zone or reactor and is usually conducted in the absence of oxygen.
• the temperatures employed usually vary from about 300 to about 1,000 C.
• this thermal cracking process is conducted while the olefins are in a gaseous state.
• the olefins may be cracked in relatively pure form or a diluent may be employed.
• a methyl group attached to the second carbonatom of the main or straight portion of the chain, and the double bond is in the 2 position such as olefin being Z-methyl pentane-2
• the predominant products obtained are Z-methyl butadiene-l,3 (isoprene) which is a diolefin, and methane, a paraifin.
• Z-methyl butadiene-l,3 isoprene
• methane a paraifin.
• a 6 carbon olefin such. as Z-methyl pentane-l which has the double bond in the 1 position and the methyl group in the 2 position is.
• olefins which do not contain in their molecular make-up a carbon-carbon bond in the position beta to the double bond and, therefore, do not undergo the same reactions when subjected to thermal decomposition conditions.
• These olefins are ethylene, propylene, butene-2, isobutene, 2-methyl butene-2, and 2,3-dimethyl butene-Z, and are usually referred to as refractory olefins.
• these refractory olefins are not considered to be within the scope of the olefins which are to be cracked in accordance with this invention.
• olefins which have in their molecule a carbon-carbon bond which is in a position beta to the double bond, to conditions of temperature and time suitable or sufiicient to cleave the carbon-carbon bond which is in a position beta to the double bond, while said olefin is in the presence of an olefin cracking promoter comprising methylene chloride.
• the conditions which may be employed in the practice of this invention may vary widely, for instance the cracking temperature may vary broadly from about 400 C. to about 900 C. However, more preferred cracking temperatures are from about 600 C. to about 750 C.
• the time in which the olefins are in the cracking zone may range broadly from about 0.001 to about 3.0 seconds. However, it is more preferable to employ times varying from about 0.05 to about 0.5 second. These times which are referred to are usually called residence times and are defined as the time required for one mol of gas whether it be pure olefin or in mixture with the diluents to pass through the cracking zone.
• olefins are cracked either as pure hydrocarbons or as mixtures with other a diluent gases.
• diluent gases may be such materials as steam, carbon dioxide, hydrogen, parafiins, the refac tory olefins, or any other inert gaseous substance which does not materially affect the cracking process or react with either the feed stock or products other than to act generally as a diluent.
• the ratio of this diluent gas may be widely varied depending on conditions, but it is usually employed in mol ratios of from about 0.5/1 to about 15/1 moles of diluent per mol of olefin. If more than about 15/1 mol ratio is employed, the process tends to become uneconomical. Therefore, it is preferred to usea diluent to olefin mol ratio ranging from about 2/1 to about 4/1.
• the pressure employed in the cracking zone may be varied from a low of 10 milliliters of mercury to 500 pounds per square inch gauge or even higher. However, it is usually preferred that the pressure range from about atmospheric to about 100 p.s.i. with about 1-2 atmospheres being preferred.
• the olefin cracking promoter employed in this invention is methylene chloride.
• the amount of methylene chloride employed in the practice of this invention has not been found to be too critical. Of course, sufficient promoter should be employed to obtain some beneficial effect, on the other hand, for the sake of economy, no more promoter should be employed than is necessary. Generally it has been the practice to employ from about 0.5 to about 50 mole percent of methylene chloride based on the total moles of olefin desired to be cracked, with about 5 to mol percent being preferred.
• Example in this example 3-methyl pentene-2 was the olefin cracked. Steam was used as a diluent at a mole ratio of water to hydrocarbon of approximately 3/ 1.
• olefins which will decompose to form predominantly Z-ethyl butadiene-l,3 when cracked in accordance with the practice of this invention are 3-ethyl pentene-2; 2-ethyl pentene-2; 3-ethyl hexene-Z; 3-meth- :rl-Z-ethyl pentene-l.
• olefins which will decompose to form predominantly 2,3-dimethyl butadiene-1,3 rwhen cracked in accordance with the practice of this invention are 2,3-dimethyl pentene-2; 3-methyl-2-ethyl butene-l; 2, 3,3-trirnetl1yl butene-l; 2-isopropyl pentene-l; 2,3,3-trimethyl pentene-l; and 2,3-dimethyl heptene-2.
• 3-methyl hexeue-3; 3-methyl heptene-3; 3,4-dimethyl hexene-2; 3,6-dimethyl heptene-3.
• olefins which will decompose to form predominantly 2-methyl pentadiene-l,3 and 4- methyl pentadiene-l,3 when cracked according to the practice of this invention are 2,4-dimethyl pentene-Z; 2- methyl heptene-3; 4,4-dimethyl hexene-Z; Z-propyl pentene-Z; 2-methyl-3-ethyl pentene-l; 2,6-dimethyl heptene- 3 and 2-propyl hexene-l.
• olefins which will decompose to form predominantly piperylenes when cracked in accordance with the practice of this invention are hexene-3; 4-methyl pentene-Z; heptene-3; 4-methyl hexene-Z; octene- 3; 4-methyl heptene-2; 6-methyl heptene-3; 3-ethyl hexene-1; 4-methyl-3-ethyl pentene-Z; 4,5-dimethy-l heptene- 2; and 4,5,5-trimethyl hexene-Z.
• An isoprene producing process which comprises providing a mixture of (a) at least one olefin from the group of 2-methyl pentene-2; 3-methyl pentene-2; 2-ethy-l butene-l; 2,3-dimethyl butene-l; Z-methyl hexene-Z and S-methyl hexene-2 and (b) at least 0.5 mol percent, based on the total mols of said olefin, of methylene chloride, subjecting said mixture to temperatures ranging from about 400 C. to about 900 C.
• the method of preparing isoprene which comprises subjecting 3-methyl pentene-Z in the presence of steam at a mole ratio of water to hydrocarbon of approximately 3/1 and methylene chloride in the amount of from about 5 to 10 mole percent based on the total moles of said 3- methyl pentene-Z to temperatures varying from about 600 to about 750 C. for times varying from about 0.05 to about 0.5 second, thereby cleaving the carbon-to-carbon bond in the position beta to the double bond to form isoprene.
• the method of preparing isoprene which comprises subjecting 2-methyl pentene-2 in the presence of steam at a mole ratio of water to hydrocarbon of approximately 3/1 and methylene chloride in the amount of from about 5 to 10 mole percent based on the total moles of said 2- methyl pentene-2 to temperatures varying from about 600 to about 750 C. for times varying from about 0.05 to about 0.5 second, thereby cleaving the carbon-to-carbon bond in the position beta to the double bond to form isoprene.
• a butadiene-1,3 producing process which comprises providing a mixture of (a) at least one olefin from the group of pentene-Z and hexene-2; and (b) at least 0.5 mol percent, based on the total mols of said olefin, of methylene chloride, subjecting said mixture to temperatures ranging from about 400 C. to about 900 C. for periods of time ranging from about 0.05 to about 0.5 second at pressures not exceeding about 100 p.s.i., to cleave the carbon-to-carbon single bond which is in the position beta to the double bond of said olefin, thereby forming butadiene-1,3 and recovering said butadiene-1,3.
• a 2-ethy1 butadiene-l,3 producing process which comprises providing a mixture of (a) at least one olefin from the group of S-ethyl pentene-Z; 2-ethyl pentene-Z and 3-ethyl hexene-Z and (b) at least 0.5 mol percent, based on the total mols of said olefin, of methylene chloride, subjecting said mixture to temperatures ranging from about 400 C. to about 900 C.
• a piperylene producing process which comprises providing a mixture of (a) at least one olefin from the group of hexene-3; 4-methyl pentene-2; heptene-3 and 4- methyl hexene-2 and (b) at least 0.5 mol percent, based on the total mols of said olefin, of methylene chloride, subjecting said mixture to temperatures ranging from about 400 C. to about 900 C. for periods of time ranging from about 0.05 to about 0.5 second at pressures not exceeding about 100 p.s.i., to cleave the carbon-tocarbon single bond which is in the position beta to the double bond of said olefin, thereby forming piperylene and recovering said piperylene.
• a 2,3-dimethyl butadiene- 1,3 producing process which comprises providing a mixture of (a) at least one olefin from the group of 2,3-dimethyl pentene-2; S-methyl-2-ethyl butene-l and 2,-3-dimethyl heptene-Z and (b) at least 0.5 mol percent, based on the total mols of said olefin, of methylene chloride, subjecting said mixture to temperatures ranging from about 400 C. to about 900 C.
• a S-methyl pentadiene-1,3 producing process which comprises providing a mixture of (a) at least one olefin from the group of 3-methyl hexene-3; 3,4-dimethyl hexene-2 and 3-methyl heptene-3 and -(b) at least 0.5 mol percent, based on the total mols of said olefin, of methylene chloride, subjecting said mixture to temperatures ranging from about400" C. to about 900 C.
• a 2-methyl pentadiene-l,3 producing process which comprises providing a mixture of (a) at least one olefin from the group of 2,4-di-methyl pentene-2; 2-methyl heptene-3 and 2-propyl pentene-Z and (b) at least 0.5 mol percent, based on the total mols of said olefin, of methylene chloride, subjecting said mixture to temperatures ranging from about 400 C. to about 900 C.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

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  • BE BE636789D patent/BE636789A/xx unknown
  • NL NL297566D patent/NL297566A/xx unknown
• 1962
  • 1962-09-07 US US222177A patent/US3296327A/en not_active Expired - Lifetime
• 1963
  • 1963-08-09 GB GB31505/63A patent/GB970469A/en not_active Expired
  • 1963-09-03 CH CH1089663A patent/CH439257A/de unknown
  • 1963-09-06 DE DEG38620A patent/DE1296620B/de active Pending

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