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
  • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
  • C10G45/44—Hydrogenation of the aromatic hydrocarbons
• • 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
  • C10G47/02—Cracking of hydrocarbon oils, in the presence of hydrogen or hydrogen- generating compounds, to obtain lower boiling fractions characterised by the catalyst used
  • C10G47/10—Cracking of hydrocarbon oils, in the presence of hydrogen or hydrogen- generating compounds, to obtain lower boiling fractions characterised by the catalyst used with catalysts deposited on a carrier
  • C10G47/12—Inorganic carriers
  • C10G47/14—Inorganic carriers the catalyst containing platinum group metals or compounds thereof
• • 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
  • C10G47/02—Cracking of hydrocarbon oils, in the presence of hydrogen or hydrogen- generating compounds, to obtain lower boiling fractions characterised by the catalyst used
  • C10G47/10—Cracking of hydrocarbon oils, in the presence of hydrogen or hydrogen- generating compounds, to obtain lower boiling fractions characterised by the catalyst used with catalysts deposited on a carrier
  • C10G47/12—Inorganic carriers

Definitions

• the invention relates to a new process for the conversion of a heavy oil fraction, especially a heavy oil fraction containing a limited amount of asphaltenic constituents, into lighter components.
• heavy fractions e.g. fractions boiling between 370-520 C
• cracking processes such as fluidized catalytic cracking, hydrocracking and thermal cracking, in order to convert these high boiling fractions into more valuable lighter fractions.
• Kerosene usually has a boiling point between about 150 and about 270 ° C and is mainly used for jet fuel.
• a major quality parameter for kerosene and related to the burning properties thereof is the smoke point.
• Gas oil usually has a boiling point between about 250 and about 370 ° C and is mainly used as fuel for compression-ignition engines.
• Important quality parameters comprise its ignition quality as expressed by the cetane number and its cold flow properties as expressed by the cloud point.
• Fluidized catalytic cracking is usually performed at a relatively low pressure (1.5 to 3 bar), and at relatively high temperatures (480-600 C) in the presence of an acidic catalyst (for instance zeolite containing catalysts).
• the reaction is carried out in the absence of hydrogen and the residence time of the feed is very short (0.1-10 seconds).
• a large amount of carbonaceous materials (coke) is deposited onto the catalyst (3 to 8 %w of the feed).
• Continuous regeneration of the catalyst by burning-off coke is therefore necessary.
• the products obtained in this process contain relatively large quantities of olefins, iso-paraffins and aromatics boiling in the gasoline range.
• a major product obtained by fluidized catalytic cracking is a gasoline component of good quality.
• light cycle oils boiling in the kerosene range and some heavy cycle oils boiling in the gas oil range and above are obtained, both of a moderate to low quality for use as kerosene and gas oil.
• Hydrocracking is usually performed at a relatively high hydrogen pressure (usually 100-140 bar) and a relatively low temperature (usually 300 to 400 C).
• the catalyst used in this reaction has a dual function: acid catalyzed cracking of the hydrocarbon molecules and activation of the hydrogen and hydrogenation.
• a long reaction time is used (usually 0.3 to 2 I/I/h liquid hourly space velocity). Due to the high hydrogen pressure only small amounts of coke are deposited on the catalyst which makes it possible to use the catalyst for 0.5 to 2 years in a fixed bed operation without regeneration.
• the products obtained in this process are dependent on the mode of operation. In one mode of operation, predominantly naphtha and lighter products are obtained.
• the naphtha fraction contains paraffins with a high iso/normal ratio, making it a valuable gasoline blending component.
• kerosene and gas oil are mainly obtained.
• the quality of these products is moderate only, due to the presence of remaining aromatics together with an undesired high iso/normal ratio of the paraffins amongst others.
• Thermal cracking is usually performed at a relatively low or moderate pressure (usually 5 to 30 bar) and at a relatively high temperature (420-520 C) without catalysts and in the absence of hydrogen. A long reaction time is used (residence time normally 2-60 minutes).
• the middle distillates obtained from thermal cracking of high boiling distillates are of good quality as far as the ignition properties are concerned.
• the high content of olefins and heteroatoms especially sulphur and nitrogen), however, requires a hydrofinishing treatment.
• a major problem in thermal cracking is the occurrence of condensation reactions which lead to the forming of polyaromatics.
• the cracked residue from thermal cracking therefore, is of a low quality (high viscosity and high carbon residue after evaporation and pyrolysis, expressed for instance by its Conradson Carbon Residue (CCR) content).
• CCR Conradson Carbon Residue
• HCTC hydrocatalytic thermal cracking
• the present invention thus relates to a process for the conversion of a heavy oil fraction into lighter fractions, comprising passing a heavy oil fraction having a low content of asphaltenic constituents together with a hydrogen containing gas stream through a reaction zone containing a non-acidic, hydrogen activating catalyst at a temperature of 400-550 C, preferably 410-530 C, more preferably 440-510 C, and a hydrogen partial pressure of 10-60 bar, preferably 20-40 bar.
• the molecular weight reduction is essentially effected by thermal cracking of feedstock molecules.
• the novel process does not depend on the presence of acidic sites on the catalyst, which should remain active during the cracking cycle or life of the catalyst. Due to the presence of hydrogen even at relatively moderate pressure, only very small amounts of coke are deposited on the catalyst, thus making it possible to operate in a fixed bed mode (e.g. swing reactor) or a moving bed mode (e.g. bunker flow reactor).
• the middle distillates obtained are of good quality due to the high amount of n-paraffins and the low amount of olefins, in spite of the presence of a certain amount of aromatic compounds.
• the hydrogen consumption of the process is relatively low, as the aromatic compounds are hardly hydrogenated.
• a further advantage is the fact that, dependent on the catalyst, the sulphur present in the feed can be converted for a substantial part into hydrogen sulphide, thus resulting in a product, containing a relatively small amount of sulphur.
• the bottom material i.e. material boiling above the boiling point of the middle distillate products, has excellent properties (viscosity, carbon residue and sulphur content) and can be used as a valuable fuel oil blending component. Further, said heavy material is unexpectedly an excellent feedstock for a fluidized catalytic cracking reaction. When compared with a usual feedstock for a fluidized catalytic cracking reactor, for example a straight run flashed distillate, the gasoline yield and quality are similar. When compared with the bottom material obtained from a distillate thermal cracking reactor as feedstock for a fluidized catalytic cracking process a much higher gasoline yield is obtained.
• the HCTC-process does not depend on the presence of acidic sites on the catalyst.
• the HCTC process can be suitably carried out in the substantial or even complete absence of acidic sites in the catalyst.
• feeds containing a substantial amount of basic nitrogen and/or sulphur containing compounds can be processed without difficulties. Due to the presence of activated hydrogen only very small amounts of coke are deposited on the catalyst, while in fluidized catalytic cracking large amounts of coke are deposited on the catalyst, making continuous regeneration of the catalyst necessary.
• the products obtained by the present process are predominantly middle distillates of good quality together with a heavy, unconverted fraction of relatively good quality.
• the major product obtained by fluid catalytic cracking is a gasoline blending component together with a smaller amount of light cycle oil of moderate to low quality as aromatic compounds form the larger part of this light fraction.
• a gasoline blending component together with a smaller amount of light cycle oil of moderate to low quality as aromatic compounds form the larger part of this light fraction.
• HCTC is relatively insensitive to feedstock impurities, especially (basic) nitrogen and carbon residue (CCR).
• CCR carbon residue
• the process according to the present invention can be carried out during a substantial period at relatively low hydrogen pressure investment costs are considerably lower when compared with a conventional hydrocracking process.
• the hydrogen consumption in the HCTC-process is relatively low.
• iso/normal ratio of the paraffins it may be remarked that due to the radical type of cracking in the HCTC-process the iso/normal ratio of the paraffins is low, which is favourably for the ignition quality of the gas oil.
• the classic hydrocracking process results in a high iso/normal ratio due to the carbonium ion reaction mechanism, thus unfavourably affecting the quality, of the middle distillates, especially the ignition quality of the gas oil.
• a suitable feed for the HCTC-process according to the present invention is a heavy oil fraction having a low content of asphaltenic constituents.
• Vacuum distillates, and/or deasphalted oils of any source and almost limitless as far as the sulphur and nitrogen content is concerned can be used.
• the content of asphaltenic constituents in the feed is less than 3%w, preferably less than 2%w, more preferably less than 1.5%w, and most preferably less than 1.0%w.
• C 7 -asphaltenes are meant, i.e. the asphaltenic fraction removed from the heavy oil fraction by precipitation with heptane.
• the feed may contain a substantial amount of carbon residue (CCR), suitably below 15%w, preferably below 10%w, more preferably below 6%w.
• CCR carbon residue
• the amount of sulphur in the feed is suitably below 10%w, preferably below 6%w, more preferably below 4%w.
• the amount of nitrogen is suitably below 6%w, preferably below 4%w.
• a vacuum distillate or flashed distillate can be used as feed having a boiling range substantially between 350 and 580 C, preferably between 370 and 520 C.
• Another very suitable feed is a deasphaltized residual oil (DAO), for instance a propane, butane or pentane deasphalted long or short residue.
• DAO deasphaltized residual oil
• synthetic distillates and/or synthetic deasphalted oils which are available in for instance complex refineries, are suitable feeds for the present process.
• a very suitable source for producing such synthetic feeds comprises the so-called hydroconversion process of residual oil fractions, for instance short residue.
• Such a hydroconversion process preferably comprises a hydrodemetallization step, followed by a hydrodesulphurization/hydrodenitrogenation step and/or a hydrocracking step.
• usually synthetic flashed distillates or synthetic deasphalted oils are processed in a catalytic cracking process. However, this results mainly in the production of gasoline but no kerosene or gas oil of acceptable quality is obtained.
• Hydrogen conversion processes such as H-oil, LC-fining and Residfining can also be used for the production of the above-indicated synthetic feeds.
• Another very suitable feed for the HCTC-process originates from a visbreaking process of for instance short residue. Upon thermally cracking a heavy residue followed by flashing or distillation of the product, a distillate can be obtained substantially boiling in the range between 350 and 520 ° C which is an excellent feedstock for the process according to the present invention.
• Mixtures of relatively heavy and relatively light feedstocks e.g. a DAO and a flashed distillate, may be used advantageously in view of reduced coke formation.
• the hydrocatalytic thermal cracking process is suitably carried out at a reaction temperature of 400-550 ° C, preferably 410-530 C, more preferably between 440-510 C, most preferably at about 450 C. It will be appreciated that a higher conversion will be obtained when the temperature is higher, as the rate of thermal cracking of hydrocarbons will be faster at higher temperatures. To obtain the same conversion rate a (slightly) higher temperature should be used for a feedstock which is more difficult to crack thermally, for instance a feedstock rich in cyclic compounds, than for a feedstock which cracks more easily.
• the space velocity of the feed in the novel HCTC process is suitably chosen between 0.1 to 10 I/l/h, preferably between 0.5 to 6 I/I/h, more preferably between 1.0 to 5 I/I/h.
• the hydrogen partial pressure under which the HCTC-process is carried out suitably lies between 10-60 bar, preferably 20-40 bar, more preferably about 25 bar.
• the total pressure in the reactor usually will be between 15 and 65 bar, and is preferably between 25 and 45 bar, more preferably about 30 bar.
• the hydrogen partial pressure at the reactor inlet usually will be 3-10 bar higher than at the outlet of the reactor.
• the catalysts to be used in the process according to the present invention should contain a hydrogen activating function.
• Suitable catalysts comprise one or more group IVa, group Vlb or group VIII metals.
• Suitably supports such as silica, alumina, aluminium phosphates, spinel compounds, titania and zirconia can be used.
• Conventional Group Vlb and VIII metal combinations can be employed.
• the term "non-acidic" in this specification relates to the substantial absence of one or more active acidic sites in the catalyst which are able to accelerate the cracking reaction of hydrocarbons via carbonium ion chemistry. Under initial reaction conditions some acidic sites may be present. However, these acidic sites rapidly deactivate due to coke formation and basic nitrogen adsorption whilst the hydrogen activating function remains substantially unchanged.
• the catalyst comprises a group VIII noble metal the use of palladium or platinum is preferred.
• the catalyst comprises a group IVa metal preferably tin is used.
• the catalyst comprises a group Vlb metal, preferably molybdenum, chromium or tungsten is used.
• a group VIII non-noble metal preferably iron, cobalt or nickel is used.
• Preferred catalysts are those catalysts which show a distinct but limited hydrodesulphurization activity. These catalysts show a very low coke formation together with relatively good product properties for the middle distillate fraction.
• the second order rate constant of the hydrodesulphurization reaction under the HCTC conditions lies between 0.1 and 1.0, more preferably between 0.2 and 0.5 1/(h.%S), defined under stationary conditions at 450 ° C and using Kuwait flashed distillate.
• the hydrogen/feed ratio of the process according to the present invention may be varied over a wide range.
• a suitable hydrogen/feed ratio lies between 50 NI/kg and 5000 NI/kg, especially between 100 NI/kg and 2000 NI/kg. It is preferred to use a hydrogen/feed ratio between 100 and 500 NI/kg, more preferably between 200 NI/kg and 400 NI/kg. Using these preferred low hydrogen/feed ratios the coke laydown on the catalyst is surprisingly very low. Furthermore, a high cracking conversion is obtained. When compared with a conventional hydrocracking process the hydrogen/feed ratio is significantly lower for the process of the present invention, which is beneficial for process economics.
• the usual hydrogen/feed ratio in hydrocracking operations lies between 700 and 1500 NI/kg. Generally in hydroprocessing high hydrogen/feed ratios are necessary to suppress coke-formation and to improve the conversion rate. Surprisingly, in the HCTC process a low gas rate is not only possible but also beneficial with respect to both coke formation and conversion.
• the above described preferred hydrogen/feed ratio of 200 to 400 NI/kg is used in combination with a catalyst comprising a group VIII noble metal, preferably palladium and/or platinum.
• a catalyst comprising a group VIII noble metal, preferably palladium and/or platinum.
• the hydrogen containing stream comprises a mixture of hydrogen and hydrogen sulphide.
• Carrying out the HCTC-reaction with a mixture of hydrogen and hydrogen sulphide leads to an increase of both conversion level and the selectivity to middle distillates.
• the amount of hydrogen sulphide in the mixture present in the reactor is suitably up to 50% (v/v) of the amount of hydrogen.
• an amount of hydrogen sulphide is used between 1 and 30%, more preferably between 5 and 25%, and most preferably about 10%.
• the HCTC reaction according to the present invention is suitably carried out in a fixed bed mode, e.g. a trickle bed downflow reactor.
• a fixed bed mode e.g. a trickle bed downflow reactor.
• two or more fixed bed are used, operated in a swing-operation.
• the HCTC reaction is conveniently carried out in an upflow fixed bed reactor, especially when relatively light feedstocks are used.
• Application of an upflow reactor in that case will result in a reduced rate of coke deposition on the catalyst, thereby increasing the possible run lenght between two catalyst regenerations.
• the reduction of the amount of coke on the catalyst in the upflow mode can be 50% or more when compared with the downflow mode.
• Other preferred modes of operation the process according the present invention are moving bed operations, e.g. a bunker flow reactor, and an ebullated bed operation.
• the products produced in the HCTC process can either be used as such or can be subjected to further treatment. It is possible, for instance, to subject part or all of the product(s) obtained to a desulphurization treatment, in particular a hydrodesulphurization treatment, to adjust the sulphur amount of the product to the desired amount.
• a further possibility comprises subjecting part or all of the (hydrodesulphurized) product to a hydrofinishing treatment, optionally before or after distillation of the (hydrodesulphurized) product. It is also possible to recycle at least part of the unconverted material present in the product to the HCTC reactor.
• Catalyst regeneration is suitably carried out by burning off the carbonaceous material deposited on the catalyst using an oxygen and/or steam containing gas.
• the catalyst regeneration may be carried out in the cracking reactor itself.
• the regeneration is typically carried out in a separate regenerator.
• a Kuwait flashed distillate was subjected to the hydrocatalytic thermal cracking process according to the present invention.
• the feed properties are described in Table I.
• the reaction was carried out in an isothermally operated microflow trickle bed downflow reactor.
• the catalysts were prepared by conventional pore volume impregnation techniques, unless stated otherwise.
• Commercial available carriers silica or alumina
• Catalysts 1 to 12 and 19-21 Commercially available catalysts, either as such or slightly modified, were used in experiments 13 to 18.
• the carrier properties are described in Table II.
• Inorganic precursors were used to prepare catalysts 1-12 and 19-21 (e.g. metal nitrates, ammonium molybdate).
• Chloride precursors were omitted.
• Tin was deposited as an organometallic compound (e.g. tin(II)2-ethylhexanoate).
• NiMo/Si0 2 was prepared via a deposition-precipitation technique as described in e.g. British patent specification 2,189,163. Before use, the catalysts were calcined at 350-450 ° C (except for NiMo/SiO 2 catalysts), followed by crushing to smaller particles (30-80 mesh). An overview of the catalyst formulations is given in Table III.
• the reactions were carried out at 450 ° C and a total pressure of 30 bar.
• the space velocity (LHSV) was about 1.0 l/l/h.
• the H 2 /feed ratio was between 850 and 1100 NI/kg.
• the reaction time varied between 170 and 220 hours.
• the liquid product was analyzed for the boiling point distribution using TBP-GLC. Moreover, GLC analysis of the off-gas was carried out. On basis of these analyses conversions and selectivities were calculated. The conversion has been defined as the net removal (%) of material boiling above 370 C.
• the product slate was split up into gas (C1-C4), naphtha (C5-150 C), middle distillates (150-370 C) and coke.
• the selectivities (%) have been calculated as the amount of the product in question, divided by the total amount of products (material boiling below 370 ° C and coke).
• Hydrogen consumptions were calculated on basis of CME (Combustion Mass Spectrometric Element) analyses of both the feedstock and the liquid product and of the gas analyses.
• the hydrodesulphurization (HDS) activity was determined from the sulphur content of liquid product. The results of the experiments are summerized in Table IV.
• Example II Using the same general reaction conditions as described in Example I, three different feedstocks were compared. The feedstock properties are described in Table X.
• the Kuwait flashed distillate is described in more detail in Table I.
• the Kuwait deasphalted oil is a butane-deasphalted short residue.
• the Maya synthetic flashed distillate has been produced by hydrodemetallization and hydroconversion of Maya short residue, followed by flashing. The results of the experiments are summerized in Table XI.
• a Kuwait long residue was used as feed for an HCTC experiment carried out at a temperature of 450 ° C, a pressure of 50 bar, a LHSV of 1.0 l/l/h, a H 2 /feed ratio of 1000 NI/kg and a run length of 50 hours, using catalyst No. 12.
• Feedstock properties specific gravity (d 70/4): 0.9139, sulphur (%w): 3.69, nitrogen (%w): 0.15, metals (ppm): 42, RCT (%w): 5.1, C 7 -asphaltenes (%w): 2.4.
• the net conversion was 45%.

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• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
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Citations (4)

• 1987
  • 1987-11-27 GB GB878727777A patent/GB8727777D0/en active Pending
• 1988
  • 1988-11-09 CA CA000582600A patent/CA1326464C/fr not_active Expired - Fee Related
  • 1988-11-23 CN CN88108102A patent/CN1022043C/zh not_active Expired - Fee Related
  • 1988-11-24 MX MX013917A patent/MX172342B/es unknown
  • 1988-11-24 DK DK655488A patent/DK655488A/da not_active Application Discontinuation
  • 1988-11-24 RU SU884356935A patent/RU1813095C/ru active
  • 1988-11-24 DE DE8888202685T patent/DE3871732T2/de not_active Expired - Fee Related
  • 1988-11-24 FI FI885467A patent/FI885467A/fi not_active Application Discontinuation
  • 1988-11-24 BR BR888806191A patent/BR8806191A/pt not_active Application Discontinuation
  • 1988-11-24 DD DD88322146A patent/DD283643A5/de not_active IP Right Cessation
  • 1988-11-24 ZA ZA888798A patent/ZA888798B/xx unknown
  • 1988-11-24 AR AR88312548A patent/AR244309A1/es active
  • 1988-11-24 PH PH37854A patent/PH25825A/en unknown
  • 1988-11-24 AT AT88202685T patent/ATE76893T1/de not_active IP Right Cessation
  • 1988-11-24 MY MYPI88001349A patent/MY104114A/en unknown
  • 1988-11-24 EP EP88202685A patent/EP0318125B1/fr not_active Expired - Lifetime
  • 1988-11-24 KR KR1019880015525A patent/KR890008302A/ko not_active Application Discontinuation
  • 1988-11-24 AU AU25892/88A patent/AU608389B2/en not_active Ceased
  • 1988-11-24 JP JP63294860A patent/JPH01170689A/ja active Pending
  • 1988-11-24 NO NO885257A patent/NO172898C/no unknown
  • 1988-11-24 IN IN829MA1988 patent/IN173572B/en unknown
  • 1988-11-24 ES ES198888202685T patent/ES2032004T3/es not_active Expired - Lifetime
  • 1988-11-24 NZ NZ227067A patent/NZ227067A/xx unknown
• 1992
  • 1992-06-04 GR GR920401155T patent/GR3004811T3/el unknown
• 1993
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