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
  • C10G29/00—Refining of hydrocarbon oils, in the absence of hydrogen, with other chemicals
  • C10G29/06—Metal salts, or metal salts deposited on a carrier

Definitions

• the present invention is directed to a method for reducing the Total Acid Number (TAN) of crude oils, a number that is based on the amount of carboxylic acids, especially naphthenic acids, that are present in the oil.
• TAN Total Acid Number
• naphthenic acid removal by conversion or absorption.
• many aqueous materials can be added to crudes or crude fractions to convert the naphthenic acids to some other material, e.g., salts, that can either be removed or are less corrosive.
• Other methods for naphthenic acid removal are also well known including absorption, on zeolites, for example.
• one common practice for overcoming naphthenic acid problems is the use of expensive corrosion resistant alloy materials in refinery or producer equipment that will encounter relatively high naphthenic acid concentrations.
• Another common practice involves blending of crudes with high TAN with crudes of lower TAN, the latter, however being significantly more costly than the former.
• Lazar, et al (US 1,953,353) teaches naphthenic acid decomposition of topped crudes or distillates, effected at atmospheric pressure between 600 and 750°F (315.6 to 398.9°C). However, it only recognizes C0 2 as the sole gaseous non-hydrocarbon, naphthenic acid decomposition product and makes no provision for avoiding buildup of reaction inhibitors.
• U.S. Patent No. 2,921,023 describes removal of naphthenic acids from heavy petroleum fractions by hydrogenation with a molybdenum oxide-on-silica/alumina catalyst. More specifically, the process preferentially hydrogenates oxo-compounds and/or olefinic compounds, for example, naphthenic acids, in the presence of sulfur compounds contained in organic mixtures without affecting the sulfur compounds. This is accomplished by subjecting the organic mixture to the action of hydrogen at temperatures between about 450 and 600°F (232.2 to 315.6°C), in the presence of a molybdenum oxide containing catalyst having a reversible water content of less than about 1.0 wt%. Catalyst life is prolonged by regeneration.
• WO 96/06899 describes a process for removing essentially naphthenic acids from a hydrocarbon oil.
• the process includes hydrogenation at 1 to 50 bar (100 to 5000 kPa) and at 100 to 300°C (212 to 572°F) of a crude that has not been previously distilled or from which a naphtha fraction has been distilled using a catalyst consisting of Ni-Mo or Co-Mo on an alumina carrier.
• the specification describes the pumping of hydrogen into the reaction zone. No mention is made of controlling water and carbon dioxide partial pressure.
• U.S. Patent No. 3,617,501 describes an integrated process for refining whole crude but does not discuss TAN reduction.
• the first step of the process includes hydrotreating a feed, which can be a whole crude oil fraction, using a catalyst comprising one or more metals supported on a carrier material.
• the metals are metal oxides or sulfides, such as molybdenum, tungsten, cobalt, nickel and iron supported on a suitable carrier material such as alumina or alumina that contains a small amount of silica.
• the catalyst can be employed in the form of fixed bed, a slurry or fluidized bed reactor. With regard to slurry operation, no mention is made of catalyst particle size, catalyst concentration in feed or the use of unsupported catalysts (i.e., no carrier).
• British Patent 1,236,230 describes a process for the removal of naphthenic acids from petroleum distillate fractions by processing over supported hydrotreating catalysts without the addition of gaseous hydrogen. No mention is made of controlling water and carbon dioxide partial pressure.
• Another method for removal of such acids includes treatment at temperatures of at least about 400°F (204.44°C), preferably at least about 600°F (315.56°C) while sweeping the reaction zone with an inert gas to remove inhibitors indigenous to or formed during the treatment.
• this approach is debited by the volatilization of some of the naphthenic acids, which are found in distillate and light oil fractions that flash during the thermal treatment.
• treatment temperatures may be too high for this method to be used in downstream applications where it is desirable to destroy the acids prior to pipestill furnaces, i.e., at temperatures of about 550°F (287.78°C) or below.
• TAN determined by ASTM method D-664, is milligrams of KOH required to neutralize the organic acids contained in 1.0 gram of oil.
• the instant invention is directed to a method for destroying carboxylic acids in whole crudes and crude fractions.
• the invention comprises a method for reducing the amount of carboxylic acids in petroleum feeds comprising the steps of (a) adding to said petroleum feed a catalytic agent comprising an oil soluble or oil dispersible compound of a metal selected from the group consisting of Group VB, VIB, VIIB and VIII metals, wherein the amount of metal in said petroleum feed is at least about 5 wppm, (b) heating said petroleum feed with said catalytic agent in a reactor at a temperature of about 400 to about 800°F (about 204.44 to about 426.67°C), and a pressure of about atmospheric to about 1000 psig (about 6996.33 kPa) in the substantial absence of hydrogen, and (c) sweeping the reactor containing said petroleum feed and said catalytic agent with an inert gas to maintain the combined water and carbon dioxide partial pressure below about 50 psia (about 344.75 kPa).
• TAN is defined as the weight in milligrams of base required to neutralize all acidic constituents in the oil.
• Vacuum bottoms conversion is defined as the conversion of material boiling above 1025°F (551.67°C) to material boiling below 1025°F (551.67°C).
• Figure 1 is the calculated partial pressure for water as a function of reactor pressure and rate of inert gas sweep for the process of the instant invention.
• the instant invention removes or destroys carboxylic acids (e.g., naphthenic acids) from petroleum feeds such as whole crude oils (including heavy crudes) and fractions thereof such as vacuum gas oil fractions, topped crudes, atmospheric resids, vacuum resids, and vacuum gas oil.
• carboxylic acids e.g., naphthenic acids
• the instant method reduces TAN by at least about 40% in the petroleum feed.
• the process is run at temperatures from about 400 to about 800°F (about 204.44 to about 426.67°C), more preferably about 450 to about 750°F (about 232.22 to about 398.89°C), and most preferably about 500 to about 650°F (about 260.00 to about 343.33°C).
• Pressures range from about atmospheric to about 1000 psig (about atmospheric to 6996.33 kPa), preferably about 15 to about 500 psig (about 204.75 to about 3548.83 kPa), and most preferably about 30 to about 300 psig (about 308.18 to about 2169.83 kPa).
• the amount of catalyst, calculated as catalyst metal or metals, used in the process ranges from at least about 5, preferably about 10 to about 1000 parts per million weight (wppm) of the petroleum feed being treated.
• Catalyst particle size ranges from about 0.5 to about 10 microns, preferably about 0.5 to 5 microns, and most preferably about 0.5 to 2.0 microns.
• Catalysts are prepared from precursors, also referred to herein as catalytic agents, such as oil soluble or oil dispersible compounds of Group VB, VIB, VIIB, or VIII metals and mixtures thereof. Suitable catalyst metals and metal compounds are disclosed in U.S. Patent No. 4, 134,825 herein incorporated by reference.
• An example of an oil soluble compound is the metal salt of a naphthenic acid such as molybdenum naphthenate.
• oil dispersible compounds are phosphomolybdic acid and ammonium heptamolybdate, materials that are first dissolved in water and then dispersed in the oil as a water- in-oil mixture, wherein droplet size of the water phase is below about 10 microns.
• a catalyst precursor concentrate is first prepared wherein the oil soluble or oil dispersible metal compound(s) is blended with a portion of the process feed to form a concentrate that contains at least about 0.2 wt% of catalyst metal, preferably about 0.2 to 2.0 wt% catalyst metal. See for example U.S. Patent No. 5,039,392 or 4,740,295 herein incorporated by reference.
• the resultant precursor concentrate can be used directly in the process or first converted to a metal sulfide concentrate or an activated catalyst concentrate prior to use.
• Catalyst precursor concentrate can be converted to a metal sulfide concentrate by treating with elemental sulfur (added to the portion of feed used to prepare the concentrate) or with hydrogen sulfide at 300 to 400°F (148.89 to 204.44°C) for 10-15 minutes (e.g. see U.S. Patent Nos. 5,039,392; 4,479,295 and 5,620,591 herein incorporated by reference).
• the metal sulfide concentrate can be converted into catalyst concentrate by heating at 600 to 750°F (315.56 to 398.89°C) for a time sufficient to form the catalyst, (e.g. see U.S. Patent Nos. 5,039,392; 4,740,295; and 5,620,591).
• the catalyst of the concentrate consists of nano-scale metal sulfide sites distributed on a hydrocarbonaceous matrix that is derived from the oil component of the concentrate. Overall particle size can be varied, but falls within the range of 0.5 to 10 microns, preferably in the range of about 0.5 to 5.0 microns, and more preferably 0.5 to 2.0 microns.
• the precursor concentrate the metal sulfide concentrate, or the catalyst concentrate.
• the petroleum feed is mixed with the concentrate to obtain the desired concentration of metal in the feed i.e., at least about 5 wppm, preferably about 10 to 1000 wppm.
• catalyst having a particle size of about 0.5 to 10 microns, preferably 0.5 to 5 microns and most preferably 0.5 to 2.0 microns are formed in the heating step of the process in the TAN conversion reactor.
• Preferred metals include molybdenum, tungsten, vanadium, iron, nickel, cobalt, and chromium.
• heteropolyacids of the metals can be used.
• Molybdenum is particularly well suited to the process of the instant invention.
• Preferred molybdenum compounds are molybdenum naphthenates, dithiocarbamate complexes of molybdenum (e.g. see U.S. Patent No.
• molybdenum e.g., MOLYVAN ® -L, molybdenum di(2- ethylhexyl) phosphorodithioate, supplied by R.T. Vanderbilt Company.
• small particle catalysts that are useful for the practice of the instant process include metals-rich ash from the controlled combustion of petroleum coke (e.g., see U.S. Patent Nos. 4,169,038; 4, 178,227 and 4,204,943 herein incorporated by reference). Finely divided iron based materials, satisfying the particle size constraints noted herein, such as red mud from the processing of alumina can also be used.
• the present process to decrease the amount of organic acids in petroleum feeds, is conducted without the addition of hydrogen.
• water partial pressures as high as 45 psia (310.28 kPa) can be obtained from acid decomposition alone when operating within the range of pressures claimed for this process, thus emphasizing the preference to start the process with a dry feed and to maintain a sweep gas rate to keep water pressure within specified levels.
• the catalyst may be left in the treated crude (depending on the metal type and concentration) or removed by conventional means such as filtration.
• the feedstock that was used in this study was a blend of Kome and Bolobo crudes from CHAD.
• the blend was desalted and heated to 230°F (110°C) with nitrogen purge to remove bulk water. Properties are given in Table 1.
• This example was carried out in a 300 cc (300 ml) stirred autoclave reactor.
• the reactor was operated in a batch mode with respect to the crude that was charged. Gas was flowed through the autoclave to control the concentration of inhibitors in the reaction zone.
• the reactor was charged with 100 g of the Kome/Bolobo blend, flushed with helium and then heated to 625°F (329.44°C) with stirring for 60 minute treatment at 625°F (329.44°C).
• Helium was flowed through the reactor at a rate of 0.1 liters per minute during the run.
• Example 1 was repeated except that the reactor was charged with 100 g of Kome/Bolobo blend and 0.62 g. of MOLYVAN ® -L (an amount sufficient to give 500 wppm Mo in the reactor feed).
• This compound supplied by R.T. Vanderbilt Company, is molybdenum di(2-ethylhexyl) phosphorodithioate that contains 8.1% Mo.
• Example 3 is molybdenum di(2-ethylhexyl) phosphorodithioate that contains 8.1% Mo.
• Example 2 was repeated except that the reactor product was filtered to recover catalyst solids prior to assay of the liquid.
• Example 2 was repeated except that water was fed to the reactor to reflect operation with feed that contained 1.0 wt% water.
• Table 2 illustrate that the rate of TAN destruction under relatively mild thermal conditions can be accelerated by addition of trace amounts of molybdenum, furnished as an oil soluble molybdenum compound, without addition of hydrogen (Compare Examples 2 and 3 with Example 1). Moreover, water is shown to have an inhibiting effect on TAN conversion (Compare Examples 2 and 3 with Example 4).

Landscapes

• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (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)
• Catalysts (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Priority Applications (8)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26753709

Family Applications (1)

Country Status (11)

Families Citing this family (2)

Citations (6)

• 1998
  • 1998-08-28 WO PCT/US1998/018045 patent/WO1999010451A1/en not_active Application Discontinuation
  • 1998-08-28 AU AU89244/98A patent/AU736920B2/en not_active Ceased
  • 1998-08-28 DK DK98941106T patent/DK1034236T3/da active
  • 1998-08-28 DE DE69816856T patent/DE69816856T2/de not_active Expired - Lifetime
  • 1998-08-28 JP JP2000507761A patent/JP2001514299A/ja active Pending
  • 1998-08-28 CA CA002300173A patent/CA2300173C/en not_active Expired - Fee Related
  • 1998-08-28 RU RU2000104877A patent/RU2192447C2/ru not_active IP Right Cessation
  • 1998-08-28 CN CN 98808724 patent/CN1272869A/zh active Pending
  • 1998-08-28 EP EP98941106A patent/EP1034236B1/en not_active Expired - Lifetime
  • 1998-08-28 BR BRPI9811618-5A patent/BR9811618B1/pt not_active IP Right Cessation
• 2000
  • 2000-02-25 NO NO20000952A patent/NO20000952L/no not_active Application Discontinuation

Patent Citations (6)

Also Published As

Similar Documents

Legal Events