Abstract: A process for isomerization dewaxing of a hydrocarbon feed which includes contacting the hydrocarbon feed with a large pore size, small crystal size, crystalline molecular sieve and an intermediate pore size, small crystal size, crystalline molecular sieve to produce a dewaxed product with a reduced pour point and a reduced cloud point. In a preferred embodiment, the feed is contacted with the molecular sieves sequentially, first with the large pore sieve followed by the intermediate pore sieve.

Abstract: An atmospheric distillate stream is combined with a calculated amount of lubricant extract stream. This well-mixed stream is then hydrotreated to yield a non-carcinogenic, high aromatic process oil. A desired level of high aromatic lubricant product streams and having the desired solvency properties is achieved by varying the feed stream ratio and hydrotreating conditions.

Abstract: The present invention relates to a new crystalline zeolite SSZ-57 and processes employing SSZ-57 in a catalyst.

Abstract: The invention concerns a process for improving tde pour point of a feed comprising paraffins containing more than 10 carbon atoms, in which process the feed to be treated is brought into contact with a catalyst comprising an EU-1 zeolite and at least one hydro-dehydrogenating element, at a temperature which is in the range 170° C. to 500° C., a pressure in the range 1 to 250 bar and an hourly space velocity in the range 0.05 to 100 h−1, in the presence of hydrogen in a proportion of 50 to 2000 l/l of feed. The oils obtained have good pour points and high viscosity indices (VI). The process is also applicable to gas oils and other feeds requiring a reduction of pour point. The invention also concerns an EU-1 zeolite from which a portion of elements T (Al, Ga, Fe or B) have been removed and which has an Si/T atomic ratio of at least 10.

Abstract: A method for hydrodesulfurization which comprises introducing partially desulfurized oil, which is a light oil fraction containing sulfur, and hydrogen to a reactor packed with a hydrodesulfurization catalyst, wherein the partially desulfurized oil has a sulfur content of 2000 ppm or less and preferably a polycyclic aromatic compound content of 3 wt % or more, wherein the amount of hydrogen sulfide contained in the partially desulfurized oil and hydrogen introduced to the reactor is 1.5 mol % or less with respect to that of the hydrogen introduced, and wherein the hydrodesulfurization catalyst comprises a carrier comprising a porous inorganic oxide and also comprises tungsten and one of nickel and cobalt as a metal component supported on the carrier. The method allows the production of a desulfurized light oil having a sulfur content of 50 ppm or less without the use of a special crude oil, and under operation conditions providing high productivity.

Abstract: The invention pertains to a process for the hydroprocessing of a hydrocarbon feedstock wherein said feedstock is contacted at hydroprocessing conditions with a catalyst composition which comprises bulk catalyst particles which comprise at least one Group VIII non-noble metal and at least two Group VIB metals. The Group VIII and Group VIB metals comprise from about 50 wt. % to about 100 wt. %, calculated as oxides, of the total weight of the bulk catalyst particles. The metals are present in the catalyst composition in their oxidic and/or sulfidic state. The catalyst composition has an X-ray diffraction pattern in which the characteristic full width at half maximum does not exceed 2.5° when the Group VIB metals are molybdenum, tungsten, and, optionally, chromium, or does not exceed 4.0° when the Group VIB metals are molybdenum and chromium or tungsten and chromium.

Abstract: The present invention pertains to a process for regenerating and rejuvenating an additive-based hydrotreating catalyst containing Group VIB and Group VIII hydrogenation metals. The process comprises the steps of regenerating the catalyst by contacting it with an oxygen-containing gas at a maximum temperature of 500° C., followed by rejuvenating the catalyst by contacting it with an organic additive comprising an organic compound, other than a compound that the catalyst is contacted with in the course of its use as a catalyst prior to regeneration and rejuvenation. The organic additive is incorporated into the catalyst. If necessary, the catalyst may then be dried at such a temperature that at least 50% of the additive is maintained in the catalyst. The process according to the invention makes it possible to restore the activity of a used additive-based hydrotreating catalyst to its original level, or even to improve it to above that level.

Abstract: The invention includes a process for converting biomass into C7-C10 alkylbenzenes useful as blending components for petroleum or petroleum derived fuels. The process includes a base catalyzed depolymerization of lignin within the biomass, followed by hydroprocessing of the depolymerized lignin to C7-C10 alkylbenzenes. The C7-C10 alkylbenzenes are useful for enhancing the octane level of petroleum or petroleum-derived fuels, such as gasoline. In addition, the C7-C10 alkylbenzenes are useful as intermediates in the production of numerous organic chemicals.

Abstract: The invention relates to an acidic silicoaluminate solid that has a microporous zeolitic phase that is characterized by at least one infrared band between 400-1600 cm−1, an organized mesoporosity that is characterized by the presence of at least one X-diffraction line between 20-100 Å, a silica/alumina molar ratio of between 5-250 and an acidity that is measured by infrared analysis via an area of the band at about 1545 cm−1 at least equal to 50 g of dry solid. The invention also relates to a process for the preparation of the solid, a substrate that consists of solid and at least one matrix, and a catalyst that comprises said solid. The catalyst can be used for the conversion of hydrocarbons and in particular hydrocracking.

Abstract: A hydrocracking catalyst has a carrier that has particles of a compound oxide and a binder present between these particles, and at least one metal component selected from Group 6, Group 9 or Group 10 of the Periodic Table supported on the carrier. The catalyst has a median pore diameter of 40 to 100 Å and the volume of pores whose pore diameter falls within a range of 40 to 100 Å is at least 0.1 mL/g. Moreover, the volume of pores of the catalyst whose pore diameter falls within a range of 0.05 to 5 &mgr;m is 0.05 to 0.5 mL/g, and the volume of pores whose pore diameter is 0.5 to 10 &mgr;m is less than 0.05 mL/g. This catalyst is mechanically strong enough for practical use and has a high conversion rate and middle distillate selectivity in hydrocracking of hydrocarbon oils, particularly vacuum gas oil.

Abstract: The present invention relates to new crystalline zeolite SSZ-59 and processes employing SSZ-59 as a catalyst.

Abstract: A catalyst assisted upgrading process for treating a hydrocarbon oil feed to reduce total acid number (TAN) and increase API gravity is provided herein which employs a hydroprocessing catalyst based on a catalyst support, e.g., alumina. The process includes blending the supported hydroprocessing catalyst with the hydrocarbon oil feed to form a slurry which is then treated with hydrogen at moderate temperature and pressure in, for example, a tubular reactor. Deposit formation is thus minimized or avoided.

Abstract: The present invention relates to new crystalline zeolite SSZ-59 and processes employing SSZ-59 as a catalyst.

Abstract: Process for the preparation of a middle distillate having good properties at low temperatures, which can be used as fuel, starting from a mixture of substantially linear hidrocarbons, without sulfur and containing at least 20% of a high-boiling fraction having a distillation temperature exceeding 370° C., comprising, as single reactive step, a “hydrocracking” step on said mixture of linear hydrocarbons, at a temperature ranging from 250 to 450° C. and a total pressure of 0.5 to 15 MPa, in the presence of a supported catalyst comprising: (A) a carrier of an acid nature consisting of a calcined gel of silica-alumina amorphous to X-rays having a molar ratio between silica and alumina within the range of 30 and 500, a surface area within the range of 500 and 1000 m2/g, with a porosity within the range of 0.2 and 0.

Abstract: The present invention relates to new crystalline zeolite SSZ-60 and processes employing SSZ-60 as a catalyst.

Abstract: The present invention relates to new crystalline zeolite SSZ-58 and processes employing SSZ-58 as a catalyst.

Abstract: The invention pertains to a cogel comprising oxidic compounds of one or more trivalent metallic elements selected from the group of aluminum, borium, gallium, chromium, iron, cobalt, manganese, vanadium, molybdenum, tungsten, indium, rhodium, scandium, or mixtures thereof, oxidic compounds of one or more tetravalent metallic elements selected from the group of silicon, titanium, germanium, or mixtures thereof and oxidic compounds of one or more divalent metallic elements with at least one divalent metallic element not selected from Group VIII non-noble metallic elements, wherein a) the cogel is essentially X-ray amorphous apart from saponite, if present; b) the saponite content CA of the cogel is less than 60%; c) the cogel has a surface area of at least 400 m2/g; d) the cogel has a cation-exchange capacity of at least 0.5 wt %; and e) the total of sodium and potassium contained in the cogel amounts to less than 0.5 wt %, based on the total weight of the cogel.

Abstract: The present invention relates to stevensite or kerolite type trioctahedral phyllosilicates 2:1 containing fluorine, fluorinated in synthesis in an acid medium and modified post-synthesis to bring about Si/Al and/or Mg/Al substitutions which impart acid properties to the solid. These phyllosilicates may be incorporated in the composition of catalysts used to convert hydrocarbons, in particular for hydrocracking.

Abstract: A catalyst and process is disclosed to selectively upgrade a paraffinic feedstock to obtain an isoparaffin-rich product for blending into gasoline. The catalyst comprises a support of a sulfated oxide or hydroxide of a Group IVB (IUPAC 4) metal, a first component of at least one lanthanide element or yttrium component, which is preferably ytterbium, and at least one platinum-group metal component which is preferably platinum.

Abstract: The invention relates to a catalyst that contains at least one matrix, at least one zeolite and at least one element that is deposited on the catalyst or contained in the matrix and selected from the group that is formed by the elements of groups VIB, VIII and VB, and at least one promoter element (phosphorus, boron, silicon), in which the zeolite contains in its porous network at least one element of group VB. The invention also relates to the use of this catalyst for the transformation of hydrocarbon fractions, in particular hydrorefining and hydrocracking.

Abstract: The invention concerns a catalyst comprising at least one matrix, at least one dioctahedral 2:1 phyllosilicate which is optionally synthesised in a fluorine-containing medium and optionally bridged, at least one metal selected from elements from group VIB and/or group VIII of the periodic table, boron and/or silicon, optionally phosphorous, optionally at least one group VIIA element, and optionally at least one group VIIB element. The invention also concerns the use of the catalyst for hydrocracking hydrocarbon-containing feeds.

Abstract: A catalyst comprising, in weight % with respect to the total catalyst weight 0.1% to 60% (expressed as the % by weight of oxide) of at least one hydro-dehydrogenating metal selected from the group formed by group VIB and VIII metals; 0.1% to 99% of at least one amorphous or low crystallinity porous matrix; 0.1% to 99.7% of beta zeolite; 0.1% to 20% (expressed as the % by weight of oxide) of at least one promoter element selected from the group formed by boron, silicon and phosphorous; 0 to 20% of at least one halogen; 0 to 20% (expressed as the % by weight of oxide) of at least one group VIIB element, the catalyst being especially useful for cracking hydrocarbon feeds.

Abstract: A catalytic hydrocracking process for the production of lube base oil wherein a hydrocarbonaceous feedstock is contacted with hydrogen and a metal promoted hydrocracking catalyst in a hydrocracking reaction zone at elevated temperature and pressure to obtain conversion to higher hydrogen-content hydrocarbons including lube base oil. The resulting hot, uncooled effluent from the hydrocracking reaction zone is hydrogen stripped in a hot, high pressure stripping zone maintained at essentially the same pressure as the hydrocracking zone to produce a first gaseous hydrocarbonaceous stream and a first liquid hydrocarbonaceous stream. At least a portion of the first gaseous hydrocarbonaceous stream is condensed to produce a second liquid hydrocarbonaceous stream and a second hydrogen-rich gaseous stream. The first liquid hydrocarbonaceous stream is preferably separated at a pressure greater than atmospheric pressure to provide at least one lube base oil product stream.

Abstract: The invention relates to a hydrocracking catalyst comprising at least one amorphous or poorly crystallized matrix of the oxide type, at least one element of group VB, preferably niobium, and at least one zeolite Y not globally dealuminized, at least one promoter element chosen from the group consisting of boron, phosphorus and silicon, optionally at least one element chosen from the elements of group VIB and group VIII, optionally at least one element of group VIIA. The invention also relates to the use of this catalyst for hydrocracking hydrocarbon feeds.

Abstract: A two stage process useful for cetane upgrading of diesel fuels. More particularly, the invention relates to a process for selective naphthenic ring-opening utilizing an extremely low acidic distillate selective catalyst having highly dispersed Pt. The process is a two stage process wherein the first stage is a hydrotreating stage for removing sulfur from the feed and the second stage is the selective ring-opening stage.

Abstract: The invention pertains to a carrier composition comprising (a) at least 30 wt % of a synthetic cracking component, based on the total weight of the carrier composition, which comprises oxidic compounds of one or more trivalent metallic elements, tetravalent metallic elements, and divalent metallic elements, said cracking component comprising elemental clay platelets with an average diameter of 1 &mgr;m or less and an average degree of stacking of 20 platelets per stack or less, and/or comprising a cogel with a saponite content CA of less than 60 %, in which the total of sodium and potassium amounts to less than 1 wt %, based on the total weight of the cogel, and (b) 1 −25 wt % of a zeolite Y, based on the total weight of the carrier composition, with a unit cell size below 24.35 å. The invention further pertains to a catalyst comprising said carrier composition and at least a hydrogenation metal, and a process for converting heavy feedstock into middle distillates using said catalyst.

Abstract: A process is described that can limit pressure drops during a catalytic hydrotreatment process carried out in a fixed bed reactor. The liquid feed and gaseous reactant are injected into the reactor either side of the bed and flow as a counter-current. Pressure drops are limited by homogeneously mixing solid catalytic and/or inert particles of different diameters in the bed.

Abstract: A process is provided for upgrading an oligomerization product through catalytic hydrotreating resulting in a synthetic lube base oil with improved pour point and viscosity index. The upgrading process includes contacting the oligomerization product with a catalyst system, under conversion conditions, which include the presence of hydrogen and a temperature sufficient to promote selective/minor cracking, hydrogenation and isomerization. The catalyst system contains a ZSM-5 zeolite and a group VIII metal.

Abstract: Disclosed are a process for producing aromatic hydrocarbon compounds and liquefied petroleum gas (LPG) from a hydrocarbon feedstock having boiling points of 30-250° C. and a catalyst useful therefor. In the presence of said catalyst, aromatic components in the hydrocarbon feedstock are converted to BTX-enriched components of liquid phase through hydrodealkylation and/or transalkylation, and non-aromatic components are converted to LPG-enriched gaseous materials through hydrocracking. The products of liquid phase may be separated as benzene, toluene, xylene, and C9 or higher aromatic compounds, respectively according to their different boiling points, while LPG is separated from the gaseous products, in a distillation tower.

Abstract: The invention relates to a catalyst that contains at least one partially amorphous Y zeolite, at least one metal of group VB, preferably niobium, at least one amorphous or poorly crystallized matrix, optionally at least one metal that is selected from group VIB and group VIII, optionally at least one element that is selected from the group that is formed by P, B, and Si, and optionally at least one element of group VIIA. The invention also relates to the use of this catalyst in hydrocracking and hydrorefining of hydrocarbon feedstocks.

Abstract: The invention relates to a catalyst that contains at least one matrix, a partially amorphous Y zeolite, optionally at least one metal that is selected from the group that is formed by the metals of group VIB and group VIII of the periodic table, optionally at least one element that is selected from the group that is formed by phosphorus, boron and silicon, optionally at least one element of group VIIA, and optionally at least one element of group VIIB. The partially amorphous Y zeolite has a peak rate that is less than 0.4, and a crystalline fraction that is expressed relative to a reference zeolite in sodium form and that is less than 60%. The invention also relates to the use of this catalyst in hydroconversion, in particular hydrocracking and hydrorefining of hydrocarbon feedstocks.

Abstract: A catalytic hydrocracking process wherein a hydrocarbonaceous feedstock and a liquid recycle stream is contacted with hydrogen in a hydrocracking reaction zone at elevated temperature and pressure to obtain conversion to lower boiling hydrocarbons. A liquid hydrocarbonaceous stream produced from the effluent of the hydrocracking reaction zone is fractionated in a first zone of a divided-wall fractionation zone to produce at least one liquid hydrocarbonaceous product stream and a liquid hydrocarbonaceous stream containing hydrocarbons boiling at a temperature in the boiling range of the feedstock and heavy polynuclear aromatic compounds. At least a portion of the liquid hydrocarbonaceous stream containing heavy polynuclear aromatic compounds is introduced into a second zone of the divided-wall fractionation zone to produce a stream rich in polynuclear aromatic compounds.

Abstract: A catalyst comprising 0.1-99.7% by weight of at least one alumina matrix; 0.1-80% by weight of at least one globally non dealuminated Y zeolite with a lattice parameter of more than 2.438 nm, a global SiO2/Al2O3 mole ratio of less than 8, and a framework SiO2/Al2O3 mole ratio of less than 21 and more than the global SiO2/Al2O3 mole ratio; 0.1-30% by weight of at least one group VIII metal and/or 1-40% by weight of at least one group VIB metal (% oxide); 0.1-20% by weight of at least one promoter element selected from the group formed by boron and silicon (% oxide); 0-20% by weight of at least one group VIIA element; 0-20% by weight of phosphorous (% oxide); 0.1-20% by weight of at least one group VIIB element, useful for hydrocracking processes, especially at low pressures of 7.5 to 11 MPa.

Abstract: The invention provides a process for hydrocracking hydrocarbon-containing petroleum feeds in the presence of a catalyst comprising a support containing at least one matrix, and at least one zeolite selected from the group, formed by NU-85, NU-86 and NU-87 zeolites.

Abstract: The present invention relates to a process for improving the pour point of a feed including paraffins containing more than 10 carbon atoms. Desirably, the feed to be treated is brought into contact with a catalyst based on NU-85 zeolite, at least partially in its acid form, and at least one hydro-dehydrogenating element, at a temperature which is in the range 170° C. to 500° C., a pressure in the range 1 to 250 bar and at an hourly space velocity in the range 0.05 to 100 h−1, in the presence of hydrogen in a proportion of 50 to 2000 l/l of feed.

Abstract: A catalyst comprising 0.1-99.7% by weight of at least one alumina matrix; 0.1-80% by weight of at least one globally non dealuminated Y zeolite with a lattice parameter of more than 2.438 nm, a global SiO2/Al2O3 mole ratio of less than 8, and a framework SiO2/Al2O3 mole ratio of less than 21 and more than the global SiO2/Al2O3 mole ratio; 0.1-30% by weight of at least one group VIII metal and/or 1-40% by weight of at least one group VIB metal (% oxide); 0.1-20% by weight of at least one promoter element selected from the group formed by boron and silicon (% oxide); 0-20% by weight of at least one group VIIA element; 0-20% by weight of phosphorous (% oxide); 0.1-20% by weight of at least one group VIIB element, useful for hydrocracking processes, especially at low pressures of 7.5 to 11 MPa.

Abstract: The invention concerns a hydrocracking process using a catalyst comprising at least one matrix, an IM-5 zeolite, at least one metal selected from the group formed by metals from group VIB and group VIII of the periodic table, optionally at least one element selected from the group formed by phosphorous, boron and silicon, and optionally at least one group VIIA and/or at least one group VIIB and/or at least one group VB element (in particular niobium). The invention also concerns a catalyst containing at least one matrix, an IM-5 zeolite, at least one metal from groups VIII and/or VIB and at least one promoter element which is boron and/or silicon. The catalyst can also contain at least one group VIIA element and/or at least one group VIIB element and/or at least one group VB element.

Abstract: An iron-containing crystalline aluminosilicate is provided which befits the incorporation as a component in a hydrocracking catalyst for hydrocarbon oil owing to the feature of exhibiting a highly satisfactory hydrocracking activity at no sacrifice of the yield of an middle distillate.

Abstract: The invention pertains to a catalyst at least comprising a hydrogenation metal component and a swelling synthetic clay consisting of elemental clay platelets, with the average diameter of the clay platelets not exceeding 1 micron and the average degree of stacking of the clay platelets not exceeding 20 platelets per stack. The catalyst is especially suitable for the hydroprocessing of hydrocarbon feeds, the term “hydroprocessing” encompassing all processes in which a hydrocarbon feed is treated with hydrogen. The clays which are suitable for use in the catalyst according to the invention may be prepared as described in Netherlands patent application No. 9401433.

Abstract: The invention relates to an acidic silicoaluminate solid that has a microporous zeolitic phase that is characterized by at least one infrared band between 400-1600 cm-1, an organized mesoporosity that is characterized by the presence of at least one X-diffraction line between 20-100 Å, a silica/alumina molar ratio of between 5-250 and an acidity that is measured by infrared analysis via an area of the band at about 1545 cm-1 at least equal to 50 g of dry solid.

Abstract: A process, preferably in a counter-current configuration, for selectively cracking carbon-carbon bonds of naphthenic species using a low acidic catalyst, preferably having a crystalline molecular sieve component and carrying a Group VIII noble metal. The diesel fuel products are higher in cetane number and diesel yield.

Abstract: Disclosed are silicoaluminophosphates (SAPOs) having unique silicon distributions, a method for their preparation and their use as catalysts for the hydroprocessing of hydrocarbon feedstocks. More particularly, the new SAPOs have a high silica:alumina ratio, and are prepared from microemulsions containing surfactants.

Abstract: The present invention is a process for producing a high viscosity index and low pour point lubricating oil base stock which comprises catalytically converting a hydrotreated hydrocarbon lube oil feedstock containing waxy paraffins in the presence of hydrogen and in the presence of a low acidity ZSM-5 catalyst having a highly dispersed noble metal component. The ZSM-5 catalyst is subjected to controlled acidity reduction to an alpha value below 15 prior to incorporation of the noble metal component.

Abstract: The present invention relates to a hydrotreating catalyst composed of a carrier having a Brønsted acid content of at least 50 &mgr;mol/g such as a silica-alumina carrier or a silica-alumina-third component carrier, in which the silica is dispersed to high degree and a Brønsted acid content is at least 50 &mgr;mol/g, and at least one active component (A) selected from the elements of Group 8 of the Periodic Table and at least one active component (B) selected from the elements of Group 6 of the Periodic Table, supported on said carrier. The present invention also relates to a method for hydrotreating hydrocarbon oils using the same. The hydrotreating catalyst of the present invention provides excellent tolerance to the inhibiting effect of hydrogen sulfide, high desulfurization activity, and exhibits notable effects for deep desulfurization of hydrocarbon oils containing high contents of sulfur, in particular gas oil fractions containing difficult-to-remove sulfur compounds.

Abstract: The invention relates to a hydrocracking catalyst that comprises at least one oxide-type amorphous or poorly crystallized matrix, at least one element of group VB, preferably niobium, and at least one clay that is selected from the group that is formed by the 2:1 dioctahedral phyllosilicates and the 2:1 trioctahedral phyllosilicates, optionally at least one element that is selected from among the elements of group VIB and group VIII, optionally at least one element that is selected from the group that is formed by P, B, Si, and optionally at least one element of group VIIA. The invention also relates to the use of this catalyst in hydrocracking of feedstocks that contain hydrocarbon.

Abstract: A process, preferably in a counter-current configuration, for selectively cracking carbon-carbon bonds of naphthenic species using a low acidic catalyst, preferably having a crystalline molecular sieve component and carrying a Group VIII noble metal. The diesel fuel products are higher in cetane number and diesel yield.

Abstract: Disclosed are silicoaluminophosphates (SAPOs) having unique silicon distributions, a method for their preparation and their use as catalysts for the hydroprocessing of hydrocarbon feedstocks. More particularly, the new SAPOs have a high silica:alumina ratio, and may be prepared from single phase synthesis solutions or from microemulsions containing surfactants.

Abstract: A catalytic process is provided for converting a high boiling point range petroleum stream to distillate range product which includes contacting a petroleum feedstock having a boiling range from about 600° F. to about 1100° F. with a hydrocracking catalyst having a zeolite component with a framework silica to alumina ratio of at least 200:1, preferably 2000:1, and a hydrogenation component. The process is conducted under superatmospheric hydrogen partial pressure to effect at least 20% conversion, with at least 50% of the converted product remaining in the boiling range of about 330 to about 730° F.

Abstract: A process is provided for selectively producing diesel fuel with increased cetane number from a hydrocarbon feedstock. The process includes contacting the feedstock with a catalyst which has a large pore crystalline molecular sieve material component having a faujasite structure and alpha acidity of less than 1, preferably about 0.3 or less. The catalyst also contains a dispersed Group VIII noble metal component which catalyzes the hydrogenation/hydrocracking of the aromatic and naphthenic species in the feedstock.

Abstract: A process for hydrotreating a hydrocarbon feed, comprising subjecting said feed to hydrotreating conditions in the presence of a catalyst comprising an essentially alumina-based extruded support, essentially constituted by a plurality of juxtaposed agglomerates, optionally at least one catalytic metal or a compound of a catalytic metal from group VIB (group 6 of the new periodic table notation) and/or optionally, at least one catalytic metal or a compound of a catalytic metal from group VIII (group 8, 9 and 10 of the new periodic table notation), in which the sum S of the group VIB and VIII metals, expressed as the oxides, is 0% to 50% by weight, and wherein each of these agglomerates is partly in the form of packs of flakes and partly in the form of needles, said needles being uniformly dispersed both about the packs of flakes and between the flakes, in which the alumina agglomerates are obtained by forming a starting alumina originating from rapid dehydration of hydrargillite and in which the amount of alum