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
  • C10G69/00—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one other conversion process
  • C10G69/02—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one other conversion process plural serial stages only
  • C10G69/06—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one other conversion process plural serial stages only including at least one step of thermal cracking in the absence of hydrogen
• • 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
  • C10G2400/30—Aromatics

Definitions

• the present invention relates to a combined steam cracking and hydrodealkylation process for economically producing both the ordinary olefins and diolefins obtained conventionally from high conversion steam cracking, and pure aromatic materials, e.g. naphthalene. More particularly, this invention relates to steam cracking heavy virgin crude oils or selected fractions of the products from catalytic cracking e.g.
• this invention relates in such a process to severely steam cracking such feeds boiling in the range of 400 to 650 F. under conditions to obtain 25 to 45 wt. percent conversions to C materials.
• Process for the hydrodealkylation of alkyl substituted aromatic compounds are well-known and widely used at the present time. These processes are both of the thermal non-catalytic type and of the catalytic type, e.g. utilizing a chromia on alumina catalyst. A preferred method for carrying out the thermal non-catalytic hydrodealkylation is described in S.N. 91,832, filed February 27, 1961. In all of these processes hydrodealkylation is obtained with a consumption of at least 1 mole of hydrogen per alkyl group due to the breaking off of the alkyl side chain to form the aromatic compound and a saturated aliphatic parafiin. Feed stocks for these processes are, of course, conventionally obtained from crude oil, catalytic reformate, catalytic cycle oils, etc.
• An additional advantage of the present process is that desulfurization prior to steam cracking may be used without detriment since the tetralins so formed are dehydrogenated back to alkyl naphthalenes in the steam cracking step.
• alkyl naphthalenes give considerably higher selectivities to the desired naphthalene in hydrodealkylation.
• Preferred feed stocks to be fed to steam cracking according to this invention boil in the range of 300 to 800 F. These feed stocks contain alkyl naphthalene, naphthalene, alkyl tetralins, alkyl benzenes, paraflins and small amounts of olefins.
• Preferred aromatic hydrocarbon feeds are suitably obtained from crude petroleum from catalytic cracking and less preferably from catalytic reforming.
• Preferred feed stocks from catalytic cracking boil in the range of 400 to 850 F., preferably 430 to 590 F., e.g. 430 to 560 F.; and contain 15 to 30 wt. percent, preferably 20 to 30 wt. percent, e.g. 30 wt. percent naphthalenes and alkyl naphthalenes; 2 to 6 wt. percent, preferably 4 to 6 wt. percent, e.g. 6 wt. percent alkyl tetralins; 3 to 24 wt. percent, preferably 10 to 24 wt. percent, e.g. 24 wt. percent, alkyl benzenes; and 40 to 80 wt.
• From crude oil preferred fractions boil in the range of 300 to 850 F., preferably 400 to 800 F., e.g. 500 to 750 F.; and contain 8 to 30 wt. percent, preferably 20 to 30 wt. percent, e.g. 30 wt. percent, naphthalenes and alkyl naphthalenes; 4 to 20 wt. percent, preferably 8 to 20 wt. percent, e.g. 20 wt. percent alkyl tetralins; 2 to 15 wt. percent, preferably 5 to 15 wt. percent, e.g. 15 wt. percent alkyl benzenes; and 35 to 70 wt. percent, preferably 35 to wt.
• Preferred crude oils are those having a high aromatic content obtained for example from San Joaquin (Venezuelan) or Tia Juana (Venezuelan) crude or Aramco (Near East) crude.
• a less preferred feed stock is obtained from hydroforming, preferably platinum hydroforming.
• These feeds boil in the range of 300 to 700 F., preferably 400 to 650 F., e.g. 430 to 560 F.; and contain 20 to 40 wt. percent naphthalenes and alkyl naphthalenes; 2 to 6 wt. percent, preferably 4 to 6 wt. percent, e.g. 6 wt. percent, alkyl tetralins; 20 to 40 wt. percent, preferably 30 to 40 wt.
• Steam cracking is conducted at temperatures in the range of 1100 to 1500 F., preferably 1200 to 1490 F., e.g. 1400 F., pressures of 1 to 20 p.s.i.g., preferably 1 to 10 p.s.i.g., e.g. 5 p.s.i.; for residence times of .1 to 1.0 second, preferably .1 to .4 second, e.g. .2 second, and utilizing amounts of steam in the range of50 to moles, preferably 60 to 80 moles, e.g. 75 moles per moles of feed.
• Preferred conversions to C are controlled in the range of 20 to 60 Wt. percent, preferably 25 to 55 wt. percent,
• the products from the steam cracking zone are immediately quenched and are separated by fractionation to remove the desired fraction to be fed to the hydrodealkylation reactor.
• This fraction may be a broad cut boiling in the range of 160 to 600 F., preferably 200 to 590 F., e.g. 220 to 560 F. (used to prepare both e.g. naphthalene and benzene) or alternatively may be a narrow cut containing only the naphthalene precursors boiling in the range of 400 to 600 F preferably 420 to 590 F., e.g. 430 to 560 F.
• alkyl benzene material boiling at a lower temperature than the naphthalene precursors will be valuable either for the separation of pure components, e.g. ethyl benzene from this fraction or for feeding it separately or with the naphthalene precursors to hydrodealkylation to produce benzene.
• Hydrodealkylation is conducted at temperatures in the reaction zone controlled in the range of 1100 to 1600 F., preferably 1150 to 1400 F., e.g. 1150 to 1375 F., pressures of 500 to 1000 p.s.i.g., preferably 400 to 700 p.s.i.g., e.g. 600 p.s.i.g., and for reaction times of 2 to 120 seconds, preferably 2 to 100 seconds, e.g. 50 seconds.
• the reaction is carried out in a reaction zone having a high L/ D ratio, preferably 40:1 to 150:1, e.g. 65.1, and utilizing a hydrogen quench to control the temperature of the reactants, all as described in S.N.
• the amount of hydrogen-containing gas initially supplied is 1 to 6 moles, preferably 2 to 4 moles, e.g. 3 moles per mole of the alkyl aromatic material contained in the feed.
• the hydrogen-containing gas according to the present invention should contain above 50% hydrogen, preferably above 80%, more preferably above 90%, e.g. 92% hydrogen.
• the amounts of hydrogen above described are initially supplied and additional amounts of hydrogen are supplied at quench points to control the reaction temperature in the reaction zone below 1300 F.
• the amount of additional hydrogen added in this embodiment is 2 to moles, preferably 3 to 10 moles, e.g. 7 moles per mole of aromatic material in the feed.
• all the preferred procedures described in S.N. 91,832, filed February 27, 1961 may be used in the present process. Reaction products from the hydrodealkylation reaction are immediately quenched and the desired pure naphthalene and other aromatic compounds are separated by distillation.
• Example 1 A feed stock boiling in the range of 430 to 600 F. obtained from the catalytic cracking of a 500 to 990 F. gas oil from South Louisiana crude is fed to a steam cracker operated under the following conditions.
• Product gases from the steam cracker after quenching and separation of water are fractionated to separate an aromatic concentrate boiling in the range of 430 to 590 F.
• This feed is fed to the hydrodealkylation process and contains 17 wt. percent parafiins, 13 wt. percent alkyl benzenes, 19 wt. percent indanes, wt. percent alkyl naphthalenes, 3 wt. percent tetralins and 14 wt. percent other aromatics such as acenaphthene and phenanthrene boiling in this range.
• This feed is supplied with 3.1 moles per mole of feed of a 92% hydrogen stream (the remainder being essentially methane) to a furnace at a temperature of 850 F. In this furnace the combined stream is heated to a temperature of 1100 F. in approximately 3 seconds.
• the 1100 F. stream is supplied to an internally lined 65:1 L/D reactor operating at 600 p.s.i.g.
• This quench gas is supplied at F., and the amount of the gas is 1.5 moles per mole of feed.
• the temperature is 1260 F. and 2.2 moles of the hydrogen-containing gas per mole of hydrocarbon feed (introduced at the same temperature as above) is utilized to cool the reactants to 1160 F.
• the temperature is 1310 F. and 3.5 moles of the same hydrogencontaining gas per mole of hydrocarbon feed, again at the same temperature, is used to cool the reactants to a temperature of 1160 F.
• the final quench is with recycle gas from the process without hydrogen enrichment containing 60 mole percent hydrogen, the remainder being light hydrocarbons and principally methane.
• This gas is supplied at a temperature of 100 F. and the amount of the final quench gas is 4.4 moles per mole of reactants.
• This quench rapidly cools the gases to a temperature of 1150 F.
• the approximate vapor velocity in the reactor varies from 1.5 at the inlet to 4.5 feet/second at the outlet and the contact time is about 50 seconds. For these conditions, about 95% of the alkyl aromatics are dealkylated into the desired product of benzene and naphthalene.
• Example 2 A feed stock boiling from 420 to 589 F. obtained from the catalytic cracking of a 490 to 1050 F. gas oil from a mixture of South Louisiana, North Louisiana and Louisiana-Mississippi crudes was fed to a steam cracker operating under the following conditions.
• the combined steam cracking and hydrodealkylation process which comprises steam cracking at high conversions a product stream from catalytic cracking boiling in the range of 300 to 850 F., distilling the reaction products from the said steam cracking to separate an aromatic concentrate fraction boiling within the range of to 600 F., hydrodealkylating the said aromatic concentrate fraction at temperatures in the range of 1100 to 1600 F., and separating a dealkylated aromatic from the reaction products from the said hydrodealkylation.
• the combined steam cracking and hydrodealkylation 3,145,238 5 5 process which comprises steam cracking at high converin a reaction zone having an L/D ratio in the range of sions to C in the range of 25 to 55 Wt. percent a 40:1 to 150:1 and separating adealkylated aromatic from Product Stream from l/ Cracking boiling Within the the reaction products from the said hydrodealkylation.

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)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22374943

Family Applications (1)

Country Status (4)

Cited By (15)

Citations (2)

• 0
  • NL NL279655D patent/NL279655A/xx unknown
• 1961
  • 1961-06-19 US US117808A patent/US3145238A/en not_active Expired - Lifetime
• 1962
  • 1962-05-30 DE DE19621443763 patent/DE1443763A1/de active Pending
  • 1962-05-30 GB GB20864/62A patent/GB945629A/en not_active Expired

Patent Citations (2)

Also Published As

Similar Documents