Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
  • C10G2400/20—C2-C4 olefins

Definitions

• This invention relates to an improvement in the cracking of naphtha.
• One means for obtaining such lower alkenes is by cracking naphtha derived from petroleum. Any improvement in such a cracking process whereby the yield of alkenes is improved or whereby the relative selectivity of propylene to ethylene is improved is of considerable benefit to the industry and constitutes a significant advance in the art.
• One object of the invention is to provide an improvement in the process for cracking naphtha to produce alkenes whereby the selectivity to the alkene product or the alkene product having the greater number of carbon atoms is increased.
• Another object of this invention is to provide an improvement in the process for cracking naphtha whereby the conversion to alkenes is improved.
• this invention discloses an improvement in a process for cracking naphtha having a boiling range of 90 to 400 F. and a specific gravity of 0.65 to 0.78 to alkenes and alkenes; wherein the improvement comprises United States Patent 0 admixing about 1.0 to 35 parts by weight of H S (or an amount of a compound which yields SH radicals in the cracking environment sufiicient to yield that amount of H S) per 100 parts by weight of H 8 (or the precursor thereto) with the naphtha to be cracked to form a mixture comprising H 8 (or a precursor thereof) and the naphtha, and then passing the mixture through a reactor maintained at a temperature of 1100 F. to about 2000 F. with a residence time of about 0.25 to about 2.0 seconds, and a pressure of about 0 to about 65 p.s.i.g.
• the naphtha which is cracked according to the process of this invention can include any naphtha product having the following properties:
• the mixture comprising naphtha and H 8 (or a precursor thereof) is passed to the cracking environment at a pressure of about 0 to about 65 p.s.i.g. for a residence time of about 0.25 to 2.0 seconds. If the residence time is too long, particularly at relatively low pressure, undesirable side reactions occur which militate against the beneficial effect of adding H S (or a precursor thereto) to the naphtha to be cracked.
• the cracking conversion is conducted continuously.
• a gas hourly space velocity of about 400 to about 22,000 cc. of gaseous feed volume per cc. of reactor volume per hour at STP (standard temperature pressure) is most preferably employed.
• STP standard temperature pressure
• the reaction environment is often preferably maintained at a temperature of about 1300 to about 1800" F. Below 1100 F., insufficient conversion occurs, and above 2000 F, undesirable side reactions occur.
• the range between 1300 and 1800 F. is the most commercially feasible region wherein side reactions are minimal but adequate conversion is yet obtained.
• the improved cracking conversion is optimumly conducted at a temperature of about 1400 to 1700 F. when the preferred naphthas are employed as feedstock.
• H 5 More preferably, about 2.0 to 20 parts by weight of H 5 (or an amount of a compound which yields H 5 in the cracking environment sufficient to yield that amount of H 8) per 100 parts by weight of H S (or a precursor thereof) plus the naphtha to be cracked are employed. Such levels are most commercially feasible.
• materials which yields H 8 in the cracking environment include: mercaptans, mercaptides, thioethers, carbon disulfide, ammonium sulfide, polysulfides such as disulfide oils, sulfur, and the like. Essentially any substance which will yield H 8 under the reaction conditions specified otherwise can be employed in lieu of any proportion of the H 8 specified. Which compounds will yield H 8 under the cracking environment specified are well known to the art or can readily be determined by simple experiment not amounting to invention. Mixtures of H 8 and an in situ H 8 precursor can be employed if desired.
• Gaseous diluents which are substantially entirely inert to the reaction environment can be employed if desired.
• Some examples of such diluents include: nitrogen, helium, neon, steam, methane, ethylene, and the like.
• a purpose of the diluent is to lower the partial pressure of the hydrocarbon and to minimize coking. Generally less than 1 part of diluent per part of feed is suitable.
• the H 8 (or precursor thereof) can be admixed with the naphtha and with the other components of the feedstock, if any, by any means heretofore known to the art for admixing fluids. Often, a conventional proportionator is advantageously employed.
• a suitable particulate packing material which can be, but is not limited to, a heterogeneous catalytic material.
• suitable particulate packing materials include: alumina, kaolin, magnesium oxide, silicates, and the like.
• Suitable packing material for a packed bed often has the greatest dimension of particles in the range of inch to inch.
• the H 8 (or precursor thereof) of the instant invention is believed to function as a reaction directing agent or catalyst.
• the eifect noted differs from mere metal or catalyst passivation.
• the system of the instant invention is a homogeneous system wherein reaction is efiected upon contact of the gaseous H 8 molecules plus generated radicals and the gaseous naphtha molecules plus generated radicals.
• a cracking feedstock was prepared by admixing 50 weight percent Kuwait light distillate and Kuwait natural gasoline. Chemical analysis of the mixture indicated that the molecular weight ranged from C to C hydrocarbons. Results of ASTM distillation and gas chromatog raphy of the mixture are given in the following Table I. As indicated in the table, the feedstock has a boiling point range which is representative of naphthas.
• Norn.Reaction gas temperature is approximately 80 0. lower than furnace temperature.
• Example 2 The runs of Example 1 are repeated except that an equivalent amount of hydrogen sulfide is employed in lieu of the hydrogen sulfide precursor, ammonium sulfide. Similar results are obtained.
• Example 3 The runs of Example 1 are repeated except that no steam is employed, a pressure of 65 p.s.i.g. is employed, a residence time of 0.25 second is employed, a temperature of 2000 F. is employed, and 35 parts by weight of H 8 per 100 parts by weight of naphtha are employed. Similar results are obtained to those of Example 1.

Landscapes

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

Priority Applications (9)

Applications Claiming Priority (1)

Publications (1)

Family

ID=23062091

Family Applications (1)

Country Status (9)

Cited By (11)

Families Citing this family (2)

• 1972
  • 1972-08-03 US US00277723A patent/US3803259A/en not_active Expired - Lifetime
• 1973
  • 1973-05-02 ES ES414293A patent/ES414293A1/es not_active Expired
  • 1973-05-07 DK DK249373AA patent/DK129722B/da unknown
  • 1973-05-22 DE DE2326026A patent/DE2326026A1/de active Pending
  • 1973-05-24 FR FR7318890A patent/FR2194765A1/fr not_active Withdrawn
  • 1973-06-12 JP JP48066307A patent/JPS4969602A/ja active Pending
  • 1973-08-02 NL NL7310728A patent/NL7310728A/xx unknown
  • 1973-08-03 GB GB3701373A patent/GB1408509A/en not_active Expired
• 1974
  • 1974-08-09 BE BE147467A patent/BE818687A/xx unknown

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