US3455813A - Light naphtha conversion process - Google Patents

Light naphtha conversion process Download PDF

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Publication number
US3455813A
US3455813A US567940A US3455813DA US3455813A US 3455813 A US3455813 A US 3455813A US 567940 A US567940 A US 567940A US 3455813D A US3455813D A US 3455813DA US 3455813 A US3455813 A US 3455813A
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hydrocarbons
naphtha
hydrogen
fraction
aromatics
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Expired - Lifetime
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US567940A
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English (en)
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Gerrit Hovestreydt
Johan D Logemann
Kees Delcour
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Stamicarbon BV
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Stamicarbon BV
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    • 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
    • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
    • C10G45/58—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins
    • C10G45/68—Aromatisation of hydrocarbon oil fractions
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C9/00—Aliphatic saturated hydrocarbons
    • C07C9/14—Aliphatic saturated hydrocarbons with five to fifteen carbon atoms
    • 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
    • C10G47/00—Cracking of hydrocarbon oils, in the presence of hydrogen or hydrogen- generating compounds, to obtain lower boiling fractions

Definitions

  • the present invention relates to a process for preparation of saturated aliphatic hydrocarbons containing 1-4 C atoms, in combination with aromatic hydrocarbons (benzene and its homologues), from light naphtha having a Vboiling range of 40 to 11G-180 C.
  • hydrocarbons present in light naphtha having a yboiling range of 40 to 11G-180 C. in particular those hydrocarbons containing from 5 to 7-9 carbon atoms, can, by thermal cracking at temperatures of 'ZOO-900 C., be principally converted into a major proportion of gaseous unsaturated hydrocarbons having 2-4 C atoms, along with a minor amount of methane and hydrogen,
  • such a cracking process converts, for instance, -'25 percent of the naphtha into ethylene, -55 percent into methane, propylene, and unsaturated C., hydrocarbons, and, in addition, 20-30 percent into liquid hydrocarbons.
  • the latter fraction is the so-called cracked naphtha, which in most cases has a higher aromatic content than the original naphtha (all gures referring to parts by weight).
  • liquid hydrocarbons obtained in rsuch a process have considerable value as fuel for petrol engines, due to their higher aromatic content.
  • this liquid fraction is not well suited as a starting material for the commercial recovery ⁇ of pure aromatics as ultimate products, because of its relatively low aromatic content and the presence of unsaturated hydrocarbons.
  • the light naphtha feed material is first cracked by heating, whereby a large portion of it is converted into methane, ethylene, gaseous unsaturated 3-4 carbon hydrocarbons and an aromatic-containing liquid fraction (cracked naphtha).
  • the latter fraction after the gases are separated from it, is subjected to a catalytic treatment with hydrogen, carried out under pressure and under relative mild conditions of temperature, so as to convert the olefines content thereof into saturated alkanes.
  • V The resulting naphtha is then suitable to use as a starting material for the extraction of armomatics therefrom, while subsequently, after the aromatics have been recovered, the remaining alkane-containing liquid is recycled to the thermal racking step.
  • the starting material is an oil distillate containing naphthenes.
  • This material is subjected, in the vapor phase, to a catalytic treatment whereby the naphthenes are converted to aromatics, the reaction mixture being subsequently subjected to a noncatalytic cracking process in order that the parallins having a higher boiling point than the aromatics and any remaining naphthenes as well, may be converted to olefines and parans of lower boiling point.
  • the reaction mixture is thereafter separated, by rectification, into a tar fraction, a fraction of aromatics, fractions consisting of parans and olenes, and gaseous hydrocarbons.
  • the aromatic fraction obtained must again be subjected to an extraction treatment, to effect a separation between the nou-aromaics still present in the aromatic fractionwhich do not dissolve in the extraction agent-and the aromatic properwhich form a solution with the extraction agent.
  • the present invention provides as the principal object a process in which the light naphtha is so treated as to yield (l) a liquid fraction having a high aromatic content, this content being so high that the aromatics can Ibe recovered from the fraction by a simple separatory process such as rectication, which is much cheaper than extraction, and (2) a gaseous saturated hydrocarbon fraction containing for the greater part 2-4 carbon atoms.
  • This gaseous hydrocarbons fraction is extraordinarily wellsuited for use as a starting material for the preparation of ethylene by thermal cracking, with the by-product formation of only a small amount of less valuable material, such as propylene, in addition to the ethylene.
  • the process according to the invention has the added advantage of flexibility as regards the products to be recovered. That is, by change of the reaction conditions, the relative amount of the aromatics and gaseous hydrocarbons fractions may be singly altered, as desired GENERAL DESCRIPTION OF THE INVENTION
  • the starting material light naphtha with a boiling range of 40 to 180 C.
  • the starting material is subjected to a treatment with hydrogen at certain elevated temperature and pressure and in the presence of a dehydrogenation catalyst, so that the aromatics originally present in the naphtha are preserved, While also a considerable amount of additional aromatics and, simultaneously, some 1-4 C atom saturated hydrocarbons are formed.
  • a liquid fraction rich in aromatics at least 70 percent by weight
  • the catalytic hydrogen reaction, under pressure, as provided and practiced according to this invention, essentially involves two reactions that are separately known in themselves.
  • the conditions under which the hydrogen treatment of the light naphtha takes place according to the invention are different from those under which the hydroforming of naphtha is generally performed, so that the iinal result is also different.
  • the object of the hydroforming process is the formation of aromatics, in particular toluene and xylene, and isomerization of the liquid hydrocarbons.
  • the process thus gives rises to release of free hydrogen, but is so controlled that the amount of gaseous hydrocarbons formed is as small as possible.
  • aromatics are also formed, but, in addition, a large proportion of the liquid non-aromatic hydrocarbons present in the starting material is converted into gaseous saturated 1-4 C atom hydrocarbon material, with no release of hydrogen.
  • the hydrogen treatment in general involves the consumption of a little hydrogen, c g. -3 percent by weight, calculated to the amount of naphtha treated, depending on the composition of the original naphtha and the ratio between the aromatics and the gaseous products formed.
  • the ratio of benzene to its homologs in the resulting liquid containing aromatics can be influenced in favor of benzene.
  • the desired conversions are effected with the use of normal dehydrogenation catalysts, i.e. of such metal catalysts as Cr, Mo, Pt, Pd, or other noble metals, applied to a carrier.
  • normal dehydrogenation catalysts i.e. of such metal catalysts as Cr, Mo, Pt, Pd, or other noble metals
  • platinum catalysts are used, with the platinum applied, in an amount of bet-Ween 0.1 and 2 percent by weight, to a carrier material consisting mainly of alumina or silica or a mixture of alumina and silica.
  • the conditions of temperature and pressure, and the hydrogen-to-naphtha ratio in the hydrogen treatment, are so chosen that the aromatic content in the resulting liquid fraction will be at least 70 percent by weight, this fraction otherwise consisting mainly of saturated C hydrocarbons.
  • this fraction otherwise consisting mainly of saturated C hydrocarbons.
  • half or more of the original starting material is converted into gaseous saturated C1-C4 hydrocarbons.
  • the pressures needed to achieve this end may vary, for instance, from about to 90 atm., preferably from about 25 to 60 atm.
  • the molar hydrogen-to-naphtha ratio may be from about 4 to 20, while final temperatures of, for instance, about 550 to 600 C. can be used.
  • the light naphtha may be passed over the catalyst at the rate of, say, about 0.5-10 volumes (liquid) per volume of catalyst and per hour.
  • the temperature may be lower, as the formation of aromatics will proceed at temperatures of about 450 to 525 C., but in order to effect the equally desirable conversion of the greater part of the paratiins that cannot be converted to aromatics to the desired gaseous saturated C1-C4 hydrocarbons, it is then necessary to raise the temperature by about 10D-50 C. towards the end of the hydrogen treatment.
  • the hydrogen treatment may be carried out with the catalyst mass present either as a fluid bed or as a xed bed.
  • the process according to the invention has the advantage of yielding a liquid with a high content of valuable aromatics and doing away with the necessity of recovering these aromatics by extraction, since a simpler, less costly separation, viz. by rectification, will suflice.
  • a separation process of this kind in which use is made of distillation, may be carried out, e.g. in a iirst stage, yielding a top product consisting of benzene and nonaromatic hydrocarbons and a bottom product, which in a following rectication can be separated into toluene as the top product and xylene contaminated with ethyl benzene as the bottom product.
  • the mixture obtained as the top product in the first rectication can be used for the recovery of pure benzene in a known way by subjecting it to azeotropic distillation with, for instance, acetone as an auxiliary liquid.
  • the saturated gaseous hydrocarbons obtained in the hydrogen treatment are subjected to thermal cracking. Prior t0 the cracking proper, methane and hydrogen, which do not contribute to the formation of ethylene, can be separated from these gases.
  • the starting material used in the hydrogen treatment according to the invention need not be largely freed of sulphur compounds.
  • Light naphtha having a sulphur content of, say, 1000 p.p.m. may be processed as such. Although slightly less aromatics will then be formed, the amount of gaseous hydrocarbons that can be cracked to produce ethylene will be higher.
  • naphtha is supplied through conduit 1 to reactor R, in which the hydrogen treatment under pressure is effected.
  • the liquid fraction is passed into a stripper column D, the top product from which consists of the still-dissolved gases, and the bottom liquid product is then passed to a ⁇ following rectifying column D2 through a conduit 4.
  • a separation is made between benzene and non-aromatic, mainly C5, hydrocarbonsdischarged through conduit 6-on the one hand, and the higher-boiling toluene xylene on the other hand.
  • the toluene-xylene mixture is sent, through conduit 5, to a rectifying column D3, the top product from which, owing oft through conduit 7, is toluene, and the bottom product, removed through conduit 8, the xylene, which always also contains some ethyl-benzene.
  • the mixture of benzene and parains removed as the top product from column D2 can be separated in the usual way, by distillation, with e.g., acetone as an auxiliary liquid to recover pure benzene.
  • the gaseosu mixture of hydrogen and saturated C1-C4 hydrocarbons to be discharged from separator S1 is sent,
  • hydrocarbons to be discharged from separator S2, and also the hydrocarbons recovered at the top product in distillation column D1, are passed, through conduits and 11, respectively, to cracker K1, Where the ethane, propane, and butane are subjected to an non-catalytic thermal cracking process in which ethylene is formed; the resulting reaction mixture is sent to a gas separator S3 through conduit 12.
  • the ethylene produced is discharged through conduit 13, and ethane not converted to ethylene is sent to ethane cracker K2 through conduit 14.
  • the gas mixture obtained in this crackng is again sent to gas separator S2, through conduit 16.
  • discharge conduits 15, of which only one is shown residual gases (a mixture of, chiefly, methane, propylene, and propane) are removed from the system. If desired, these residual gases can be returned to a thermal cracker, either before or after they have been separated into their constituents.
  • the process according to FIGURE II differs from that according to FIGURE I in that hydrogen treatment is carried out in several reactors arranged in series, which are designated as R1 and R2, and in that the gaseous mixture of saturated C1-C4 hydrocarbons discharged from separator S2 and stripper D1 through conduit 11 is rst sent to a gas separator S4 for the removal of methane, so that the load on the crackers will be lighter.
  • the methane fraction which always contains some components that can be cracked to produce ethylene, is then sent to gas separator S3 through conduit 18; the C2-C4 fraction to be discharged from separator S4 is fed to cracker K1 through conduit 17.
  • Reactor R1 may contain a catalyst more specifically suited for the formation of aromatics, for instance Pt on A1203, Whether or not promoted by a small amount of a halogen (Cl, F), whereas reactor R2 may contain a catalyst more specically adapted to the destructive hydrogenation of the paraflins, for instance Pt on A1203, promoted by a small amount of alkali or alkaline earth metals, or Pt on SiO2. It is also possible to raise the temperature in reactor R2 slightly above the level maintained in reactor R1, for instance 50 C. above this level.
  • reaction temperature or the temperature variation in reactor Rl can be controlled as desired by the supply of heat, Whereas in reactor R2 generally cooling will have to be applied, to remove heat generated in the destructive hydrogenation of the parains and oleines.
  • FIGURES I and II show only theprincipals of operation. Of course, in practice use is made in the hydrogen treatment of several reactors, these being taken out of operation periodically in order to regenerate the catalyst which Will have become inactive in the reactor, e.g. owing to the deposition of carbon.
  • Example I In apparatus as represented in FIGURE I a light naphtha feed material with a boiling range of 40-160 C. was rst led over a platinum-on-alumina catalyst (0.6 percent by weight of Pt, 0.66 percent by weight of Cl), at a space velocity of l litre of naphtha per litre of catalyst and per hour, together with a vefold amount of hydrogen (calculated as grammolecules), at a temperature of 656 C. and at 30 atm.
  • a platinum-on-alumina catalyst 0.6 percent by weight of Pt, 0.66 percent by weight of Cl
  • Non-aromatic mainly consisting of saturated C5 and a small amount of (l5- ⁇ - hydrocarbons 4.2
  • Example II In the same way as described in Example I a naphtha with a boiling range of 40-116 C. was processed.
  • Non-aromatics ymainly consisting of C5, and for the remaining part of C5+hydrocarbons 4.1
  • said rst stage being carried out in the presence of a catalyst composed of from about 0.1 to about 2 percent by weight of platinum metal on a carrier of A1203 promoted by halogen
  • the said second stage being carried out in the presence of a catalyst containing Pt on a carrier of A1203 promoted by alkali or alkaline earth metals, or Pt on a carrier of SiO2, wherein the temperature at the end of said treatment is between about S50-600 C., while maintaining a molar ratio of hydrogen to naphtha at a value between about 4-20, and while passing said naphtha over the catalysts at the rate of about 0.5-10 liquid volumes per volume of catalyst per hour,

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  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
US567940A 1965-07-26 1966-07-26 Light naphtha conversion process Expired - Lifetime US3455813A (en)

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NL6509667A NL6509667A (fr) 1965-07-26 1965-07-26

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US (1) US3455813A (fr)
AT (1) AT269321B (fr)
BE (1) BE684601A (fr)
CH (1) CH473071A (fr)
DE (1) DE1276265B (fr)
DK (1) DK132399C (fr)
ES (1) ES329427A1 (fr)
GB (1) GB1133263A (fr)
IL (1) IL26181A (fr)
NL (2) NL6509667A (fr)
NO (1) NO118557B (fr)
SE (1) SE341390B (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3926779A (en) * 1974-01-21 1975-12-16 Texaco Inc Upgrading of paraffinic gasoline blending components by cyclization with a platinum/magnesium oxide alumina matrix catalyst

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NZ211005A (en) * 1984-02-02 1988-03-30 Terje Rosenlund Impregnating wood
DE102004011553A1 (de) * 2004-03-08 2005-10-06 Betriebsforschungsinstitut VDEh - Institut für angewandte Forschung GmbH Messvorrichtung und Messverfahren zur Zustandsbestimmung eines Metallschmelzenstroms

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2908628A (en) * 1956-06-28 1959-10-13 Sun Oil Co Hydrocarbon conversion
US3198728A (en) * 1962-06-20 1965-08-03 Socony Mobil Oil Co Inc Method of improving front end octane rating and increasing "lpg" production

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2143472A (en) * 1936-07-20 1939-01-10 Shell Dev Process for treating hydrocarbons
DE1470593A1 (de) * 1961-02-03 1969-02-13 Metallgesellschaft Ag Verfahren zur Erzeugung von Aromaten und olefinischen Kohlenwasserstoffen

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2908628A (en) * 1956-06-28 1959-10-13 Sun Oil Co Hydrocarbon conversion
US3198728A (en) * 1962-06-20 1965-08-03 Socony Mobil Oil Co Inc Method of improving front end octane rating and increasing "lpg" production

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3926779A (en) * 1974-01-21 1975-12-16 Texaco Inc Upgrading of paraffinic gasoline blending components by cyclization with a platinum/magnesium oxide alumina matrix catalyst

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DK132399B (da) 1975-12-01
NO118557B (fr) 1970-01-12
CH473071A (de) 1969-05-31
NL128679C (fr)
DE1276265B (de) 1968-08-29
GB1133263A (en) 1968-11-13
DK132399C (da) 1976-05-03
IL26181A (en) 1970-06-17
NL6509667A (fr) 1967-01-27
SE341390B (fr) 1971-12-27
AT269321B (de) 1969-03-10
BE684601A (fr) 1967-01-26
ES329427A1 (es) 1967-09-01

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