Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
  • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
  • B01J29/7034—MTW-type, e.g. ZSM-12, NU-13, TPZ-12 or Theta-3
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
  • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
  • B01J29/72—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing iron group metals, noble metals or copper
  • B01J29/74—Noble metals
  • B01J29/7469—MTW-type, e.g. ZSM-12, NU-13, TPZ-12 or Theta-3
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/40—Catalysts, in general, characterised by their form or physical properties characterised by dimensions, e.g. grain size
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
  • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
  • C01B39/42—Type ZSM-12
• • 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
  • C10G45/60—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 characterised by the catalyst used
  • C10G45/64—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 characterised by the catalyst used containing crystalline alumino-silicates, e.g. molecular sieves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
  • B01J2229/30—After treatment, characterised by the means used
  • B01J2229/42—Addition of matrix or binder particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/61—Surface area
  • B01J35/615—100-500 m2/g
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/63—Pore volume
  • B01J35/633—Pore volume less than 0.5 ml/g

Definitions

• the invention relates to a zeolite of the ZSM-12 type, to a catalyst which is suitable in particular for the hydroisomerization of higher paraffins, to a process for producing such a zeolite of the ZSM-12 type or such a catalyst, and to the use of the catalyst.
• the isomerization of paraffins is one of the most important refinery processes. Very recent legal restrictions in the use of aromatics and methyl tert-butyl ether in automotive gasoline are making the isomerization of higher paraffins (greater than C 5 ) in particular one of the most important alternatives for increasing the octane number in automotive gasoline. This is especially true of the isomerization of C 8 paraffins.
• zeolites were investigated for their surface acidity and their catalytic activity. At temperatures of more than 290° C., n-octane is converted at conversion rates of about 50% with selectivities of from 27 to 41% to isooctanes.
• A. Katovic and G. Giordano (Chemistry Express, Vol. 6, No. 12, 969-972 (1991)) describe the synthesis of ZSM-12 zeolites from the following hydrogel system: x Na 2 O:y TEABr:z Al 2 O 3 :50 SiO 2 :1000 H 2 O (where 2.5 ⁇ x ⁇ 7.5; 3.5 ⁇ y ⁇ 10 and 0 ⁇ z ⁇ 1).
• an Na 2 O/SiO 2 ratio 0.1
• a TEABr/SiO 2 ratio 0.2
• the following conditions are recommended: Si/Al in the region of 50, OH ⁇ /TEA + in the region of 1 and H 2 O/OH ⁇ in the region of 100.
• U.S. Pat. No. 5,800,801 describes an MTW zeolite, a process for its production and its use in the cracking of hydrocarbons.
• the MTW zeolite is also referred to as ZSM-12 zeolite.
• the zeolite has a certain x-ray diffraction pattern, and also a specific surface area of more than 300 m 2 /g.
• an aqueous solution of sodium silicate is prepared, to which a solution of tetraethylammonium hydroxide and an aqueous solution of aluminum nitrate are added, the amounts of the individual components being selected such that: SiO 2 /Al 2 O 3 : >120; TEA + /SiO 2 : 0.2-0.95; H 2 O/SiO 2 : 20-300; OH ⁇ /SiO 2 : 0.4-0.7.
• U.S. Pat. No. 3,970,544 and DE 22 13 109 C2 describe ZSM-12 zeolites, processes for their preparation and their use for converting hydrocarbons.
• the SiO 2 /Al 2 O 3 ratio in the ZSM-12 zeolites described is between 49 and 300.
• the silicon source used is colloidal silicon oxide.
• a zeolite of the ZSM-12 type as claimed in claim 1 .
• Advantageous developments of the zeolite of the ZSM-12 type are the subject matter of the dependent claims.
• the invention provides a catalyst which comprises the inventive zeolite of the ZSM-12 type. Further developments of this catalyst are the subject matter of the claims dependent upon claim 8 .
• the invention therefore first provides a zeolite of the ZSM-12 type, especially for use in catalysts for the hydroisomerization of higher paraffins, which
• the inventive zeolite of the ZSM-12 type features a particularly high porosity. This is manifested clearly in the specific pore volume determined by mercury porosimetry, especially when it is placed in relation to the pore radius. In mercury porosimetry, the inventive zeolite of the ZSM-12 type exhibits, in a pore radius range of 4-10 nm, a specific volume of from about 30 to 200 mm 3 /g, preferably about 80-150 mm 3 /g, especially preferably about 100-130 mm 3 /g. ZSM-12 zeolites which have been produced using colloidal silica have a distinctly smaller specific pore volume in this pore radius range.
• Typical values for a pore radius range of 4-10 nm are in the region of about 3 mm 3 /g.
• the inventive zeolite of the ZSM-12 type has a specific pore volume of about 70-700 mm 3 /g, preferably about 150-550 mm 3 /g, especially preferably about 200-500 mm 3 /g.
• a zeolite of the ZSM-12 type produced using colloidal silica exhibits, in the pore radius range of 10-100 nm, typically a specific pore volume of about 40 mm 3 /g.
• the pore volume is determined by mercury porosimetry to DIN 66133 at a maximum pressure of 4000 bar (cf. Example 11).
• the aforementioned porosimetry values are determined on the zeolites which have been washed, dried and calcined according to Example 1. The above ranges for the specific volume also apply to the washed and dried but uncalcined zeolites.
• the inventive zeolite of the ZSM-12 type has a high proportion of large pores, as obtainable only in the inventive composition according to claim 1 .
• the inventive zeolite of the ZSM-12 type exhibits, in nitrogen porosimetry in the range of 30-200 ⁇ , a specific volume of 0.05-0.40 cm 3 /g, preferably 0.10-0.35 cm 3 /g, especially preferably 0.15-0.30 cm 3 /g. It is assumed, without the invention being restricted to this assumption, that the above porosimetry of the inventive zeolite is also responsible for the high catalytic activity and reflects the numerous cavities between the small primary crystals.
• the specific pore volume is determined by nitrogen porosimetry according to DIN 661134 as specified in Example 12.
• the above porosimetry values may be determined on the dried uncalcined zeolites or preferably on the calcined zeolites.
• the above porosimetry values are determined on zeolites which have been washed, dried and calcined according to Example 1. The above ranges for the specific volume also apply to the washed and dried but uncalcined zeolites.
• the zeolite is synthesized directly with the desired SiO 2 /Al 2 O 3 ratio by appropriately adjusting the amount of silicon source and aluminum source in the primary synthesis of the zeolite (in the synthesis gel composition).
• the SiO 2 /Al 2 O 3 ratio in the synthesis gel composition corresponds approximately to the SiO 2 /Al 2 O 3 ratio in the ZSM-12 zeolite.
• the SiO 2 fraction in the synthesis gel composition deviates, in a manner familiar to those skilled in the art, generally by about ⁇ 10% from the fraction in the finished zeolite. Only in the event of very large or very small fractions of SiO 2 are larger deviations observed.
• the inventive direct synthesis enables a homogeneous structure of the zeolite and prevents what is known as “extra-framework” aluminum, which is formed in the subsequent dealumination after the zeolite synthesis, and can disadvantageously influence the activity and selectivity of the ZSM-12 zeolite.
• the molar TEA + /SiO 2 ratio established in the synthesis gel is preferably selected at a low level.
• the molar TEA + /SiO 2 ratio is preferably selected between about 0.10 and 0.18.
• the molar SiO 2 /Al 2 O 3 ratio is preferably established within the range of from about 50 to about 150.
• the synthesis gel should preferably also have a comparatively low alkali metal and/or alkaline earth metal content, and the molar M 2/n O:SiO 2 ratio may advantageously lie between about 0.01 and 0.045.
• M 2/n O is the oxide of the alkali metal or alkaline earth metal having the valency n.
• a comparatively low molar ratio of H 2 O:SiO 2 of from about 5 to 18, preferably from 5 to 13, in the synthesis gel is used.
• the metal ion M selected is preferably an alkali metal, especially preferably sodium.
• a precipitated silica is used which, in comparison to colloidal silica, has a lower reactivity. This also allows the mean size of the resulting primary crystals, which should be less than 0.1 ⁇ m in accordance with the invention, to be influenced.
• the precipitated silica preferably has a BET surface area of ⁇ 200 m 2 /g.
• the average size of the primary crystals in the inventive catalyst is comparatively low and is less than 0.1 ⁇ m.
• the primary crystal size may be determined from scanning electron micrographs, by analyzing a number of primary crystals with regard to length and width. The measured primary crystal sizes are then used to form the arithmetic mean.
• the primary crystals present in the inventive catalyst generally do not have any significant differences in their lateral elongation in comparison to their longitudinal elongation. Should this occur in the individual case, the largest and the smallest diameter of the crystal are averaged in the determination of the primary crystal size.
• the procedure is to produce scanning electron micrographs of the washed and dried (cf. Example 1) but uncalcined, template-containing ZSM-12 zeolite at a magnification of from 68 000 to 97 676 (instrument: Leo 1530; LEO GmbH, Oberkochen, Germany).
• 30 primary crystals are selected which are clearly delimited from one another, and their longitudinal and lateral elongation is measured (cf. above) and the mean is determined therefrom.
• the diameters determined in this way are then used to form the arithmetic mean, i.e. the mean primary crystal size.
• the primary crystal size is substantially not influenced by calcining.
• the primary crystal size can therefore be determined directly after the synthesis of the zeolite of the ZSM-12 type, and also after the calcination.
• the primary crystals preferably have a size in the range of from about 10 to 80 nm, more preferably in the range of from about 20 to 60 nm.
• the inventive catalyst thus comprises comparatively small primary crystals.
• the primary crystals of the zeolite are combined at least partly to agglomerates.
• the primary crystals have been combined to agglomerates in a proportion of at least 30%, preferably at least 60%, especially preferably at least 90%.
• the percentage data are based on the total number of primary crystals.
• the agglomerates preferably have a large number of cavities on their surface and interstices between the individual primary crystals.
• the agglomerates thus form a loose structure composed of primary crystals with cavities accessible from the agglomerate surface or interstices between the primary crystals.
• the agglomerates appear as a sponge-like structure with a highly fissured surface which is generated by the loose coherence of the primary crystals.
• the micrographs preferably show relatively large spherical agglomerates which have a broccoli-like shape.
• the structured surface is formed from primary crystals which form a loose structure. Between individual crystals, cavities are formed, from which channels lead to the surface, which appear on the micrographs as darkly contrasted points on the surface. Overall, a porous structure is obtained.
• the agglomerates formed from primary crystals are preferably in turn joined to form larger, superordinate agglomerates, between which individual channels with larger diameter are formed.
• conventional zeolites of the ZSM-12 type exhibit, in scanning electron micrographs, a comparatively less structured and apparently smoother surface of the agglomerates. This is probably caused by the substantially lower porosity of the zeolite.
• the inventive zeolite of the ZSM-12 type thus preferably forms an open agglomerate structure, i.e. a structure in which the primary crystals are not combined in such an ordered way that a substantially smooth or continuous surface of the agglomerates is obtained. Instead, the primary crystals form bridges between adjacent primary crystals, so that cavities are formed between adjacent primary crystals.
• the particular agglomerate structure enables efficient access of the molecules to be converted to the active sites of the inventive catalyst and rapid transport of the converted molecules away from the active sites, and also particularly advantageous utilization of the catalytic activity even in the interior of the primary crystal agglomerates.
• the high catalytic activity of the inventive catalysts in the hydroisomerization of paraffins is influenced by the efficient diffusion of the paraffins to the active sites in the primary crystal agglomerates, as a result of which the reaction kinetics and thus also the yield of branched hydrocarbons can be improved. This enables the hydroisomerization to proceed even at comparatively low temperatures with good conversion rates and substantially without side reactions which lead to the degradation of the carbon skeleton to form low molecular weight hydrocarbons.
• the primary crystals of the inventive zeolite of the ZSM-12 type are thus preferably combined to agglomerates, the size of these agglomerates being highly variable, and it is also possible for a plurality of agglomerates to be combined to larger, superordinate agglomerates.
• the primary crystals are predominantly recognizable by scanning electron microscopy as delimited units, but are on the other hand joined over part of their surface with adjacent primary crystals to form agglomerates. Scanning electron micrographs reveal relatively large, broccoli-like structures with a highly structured surface, which have combined to larger, superordinate agglomerates. This structure is not significantly impaired or altered by the processing of the zeolite to the finished catalyst, especially by the calcining, comminution, etc.
• the number of the primary crystals not bonded into agglomerates is minimized in the inventive zeolite of the ZSM-12 type.
• Agglomerates are understood to mean combinations of a plurality of primary crystals.
• the inventive zeolite of the ZSM-12 type exhibits a high catalytic activity, especially in the hydroisomerization of higher paraffins.
• the invention therefore also provides a catalyst, especially for the hydroisomerization of higher paraffins, comprising a zeolite of the ZSM-12 type as described above.
• higher paraffins are understood to mean those having at least 5 carbon atoms.
• the catalyst comprises only the inventive zeolite of the ZSM-12 type.
• the powder obtained in the preparation of the zeolite of the ZSM-12 type which may also initially be further ground and adjusted to a certain particle size distribution, is, for example, pressed to moldings without binders.
• the catalysts may additionally also comprise further components.
• the catalyst may comprise further meso- and/or microporous materials.
• Meso- and microporous materials are understood, for example, to mean molecular sieves, especially aluminophosphates, metalloaluminates, titanosilicates and metallosilicates, for example zeolites.
• the proportion of the meso- and/or microporous materials may be between 1 and 99% by weight based on the weight of the catalyst.
• the catalyst may be processed to moldings with the aid of a binder.
• the catalyst may have a binder content of from about 10 to 90% by weight, preferably from 20 to 70% by weight.
• the binder used may be any binder which is familiar to those skilled in the art and appears to be suitable, especially silicate materials, aluminum oxide, zirconium compounds, titanium oxide, and mixtures thereof, and materials, for example cement, clay, silica/alumina.
• Preferred binders include pseudoboehmite and also silicatic binders such as colloidal silicon oxide.
• the inventive catalyst is suitable generally, but not exclusively, for conversion reactions of hydrocarbons.
• the properties of the catalyst may be modified by covering the catalyst with catalytically active components which influence its catalytic properties or which are themselves catalytically active.
• Suitable for this purpose are, for example, metals of the transition groups, particular preference being given here to the noble metals.
• Suitable examples are gold, silver, rhenium, ruthenium, rhodium, palladium, osmium, iridium and platinum, and mixtures and alloys thereof. Particular preference is given to platinum.
• the catalytically active component is generally present in the catalyst in a proportion of from 0.01 to 40% by weight based on the total face of the catalyst.
• the catalytically active component used is a noble metal, it is preferably present in the catalyst in a proportion of from 0.05 to 2% by weight.
• the particular properties of the inventive catalyst are influenced significantly by the preparation of the catalyst, such as the composition of the synthesis gel, and also the use of precipitated silica.
• the invention therefore also provides a process for producing the above-described catalyst.
• a synthesis gel composition which comprises, in aqueous solution or suspension:
• the solid obtained in the process according to the invention corresponds to the above-described zeolite of the ZSM-12 type. It has primary crystals having a mean primary crystal size of ⁇ 0.1 nm and exhibits, depending on the pore volume, the above-described distribution, determined by mercury porosimetry, of the specific pore volume.
• the silicon source used in the process according to the invention is precipitated silica and the template used is tetraethylammonium ions.
• Suitable examples are activated alumina, ⁇ -alumina, aluminum hydroxide, sodium aluminate, aluminum nitrate, or else aluminum sulfate. Particular preference is given to sodium aluminate, since it functions simultaneously as a source of alkali metal ions.
• the alkali metal ion and/or alkaline earth metal ion source used may be any customary compounds familiar to those skilled in the art.
• the alkali metal used with particular preference is sodium.
• the alkali metal sources used are in particular alkali metal hydroxides, preferably sodium hydroxide.
• the procedure in the synthesis is preferably to initially prepare a solution of tetraethylammonium hydroxide in demineralized water. Subsequently, the aluminum source, for example sodium aluminate, and also a source of alkali metal and/or alkaline earth metal ions M having the valency n, for example sodium hydroxide, is added to this solution, and the mixture is stirred until a solution of the constituents is obtained. Subsequently, the precipitated silica is added in portions to this solution to obtain a highly viscous gel.
• the synthesis of the zeolite is preferably carried out in a small amount of water as a solvent. To this end, the molar H 2 O:SiO 2 ratio is adjusted within the range from 5 to 15.
• the molar ratio of the silicon and aluminum sources in the synthesis gel composition corresponds substantially to the molar composition of the zeolite of the ZSM-12 type to be produced.
• the molar SiO 2 :Al 2 O 3 ratio in the synthesis gel composition is preferably established within the range from 50 to 150.
• the synthesis gel composition is stirred until a homogeneous gel is obtained.
• the crystallization is subsequently carried out under hydrothermal conditions, i.e. at a temperature of more than 100° C. and a pressure of more than 1 bar.
• the synthesis gel is stirred in a suitable pressure vessel.
• the crystallization is carried out preferably at temperatures of from about 120 to 200° C., especially preferably from about 140 to 180° C.
• the crystallization is particularly suitably carried out at a temperature of about 160° C.
• the crystallization time is preferably from about 50 to 500 h, in particular from about 100 to 250 h.
• the crystallization time is influenced, for example, by the crystallization temperature. Under these synthesis conditions, a solid is obtained which has primary crystals having a mean primary crystal size of not more than about 0.1 ⁇ m.
• the crystallized product is subsequently removed from the mother liquor.
• the reaction mixture can be filtered, for example, with the aid of a membrane filter press.
• a removal may, for example, also be effected by centrifugation.
• the removed solid is subsequently washed with demineralized water. The washing operation is preferably carried out until the electrical conductivity of the washing water has fallen below 100 ⁇ S/cm.
• the removed solid is subsequently dried.
• the drying is carried out, for example, under air in customary drying apparatus.
• the drying temperature is selected, for example, within the range from 100° C. to 120° C.
• the drying time is generally in the range from about 10 to 20 h. The drying time is dependent upon the moisture content of the removed solid and on the size of the batch.
• the dried solid may subsequently be comminuted in a customary manner, in particular granulated or ground.
• the solid may be calcined.
• the calcination is carried out with ingress of air, the temperatures selected being within the range from 400 to 700° C., preferably from 500 to 600° C.
• the time for the calcination is generally selected to be between 3 and 12 h, preferably 3 and 6 h.
• the times for the calcination relate to the time for which the zeolite is kept at the maximum temperature. Heating and cooling times are not taken into account.
• the content in the catalyst of exchangeable cations, especially alkali metal ions may be influenced, for example, by treatment with suitable cation sources such as ammonium ions, metal ions, oxonium ions and mixtures thereof, and the exchangeable ions, especially alkali metal ions, present in the inventive zeolite of the ZSM-12 type may be exchanged.
• suitable cation sources such as ammonium ions, metal ions, oxonium ions and mixtures thereof
• the exchangeable ions, especially alkali metal ions, present in the inventive zeolite of the ZSM-12 type may be exchanged.
• the catalyst laden with the corresponding ions may subsequently be washed again and dried. The drying is carried out, for example, at temperatures of from 110 to 130° C. for a time of from 12 to 16 h.
• the catalyst may also be calcined, for which, for example, temperatures in the range of from 460 to 500° C. can be employed for a period of from 6 to 10 h.
• the catalyst may also be ground.
• the catalyst may be used in powder form.
• the catalyst is preferably processed to moldings in order to increase the mechanical stability and for better handling.
• the inventive zeolite of the ZSM-12 type as detailed above, may, for example, be pressed to corresponding moldings with or without addition of binders.
• the shaping may also be effected by other processes, for example by extrusion.
• the resulting powder is shaped after addition of a binder, for example pseudoboehmite, to moldings.
• the moldings may subsequently be dried, for example at temperatures of from 100 to 130° C. optionally, the moldings may also be calcined, for which temperatures in the range from 400 to 600° C. are generally used.
• the catalyst is also covered with suitable activating compounds (active components).
• active components can be added in any way familiar to those skilled in the art, for example by intensive mixing, vapor deposition, saturation or impregnation with a solution, or incorporation into the zeolite.
• the catalyst is impregnated, for example, with a corresponding solution of a transition group metal or of a noble metal.
• a suitable example is an aqueous H 2 PtCl 6 solution.
• the impregnation solution is preferably adjusted in such a way that the impregnation solution is taken up fully by the catalyst.
• the catalysts are subsequently dried, for example, at temperatures of from about 110 to 130° C. for from 12 to 20 h and calcinated, for example, at from 400 to 500° C. for from 3 to 7 h.
• the inventive catalyst is suitable in particular for a modification of hydrocarbons.
• the inventive catalyst is suitable for reforming cuts from mineral oil distillation, for increasing the flowability of gas oils, for isomerizing olefins or aromatic compounds, for catalytic or hydrogenating cracking and also for oligomerization or polymerization of olefinic or acetylenic hydrocarbons.
• the catalyst is also suitable for isomerization and hydroisomerization of naphthenes.
• the invention therefore also provides for the use of the above-described catalyst for the conversion of organic compounds, especially hydrocarbons.
• Higher paraffins are understood to mean saturated linear hydrocarbons having a carbon number of more than 5 carbon atoms, in particular of at least 7 carbon atoms.
• the catalyst is suitable for the hydroisomerization of n-octane.
• the hydroisomerization is preferably carried out in the presence of aromatics, in particular of benzene.
• the hydroisomerization is carried out in the presence of hydrogen, preferably at temperatures below 290° C., preferably at from about 230 to 260° C., in particular at about 250° C.
• the pressure is carried out in the hydroisomerization preferably within a range of from 1 to 50 bar at a liquid hourly space velocity (LHSV) of from about 0.1 to 10 l per hour of hydrocarbon fed or of the hydrocarbon-containing mixture per liter of catalyst.
• LHSV liquid hourly space velocity
• a synthesis gel composition was prepared which had the following composition:
• TEAOH tetraethylammonium hydroxide
• the pressure vessel was cooled to room temperature.
• the solid product was removed from the mother liquor by filtration and subsequently washed with demineralized water until the conductivity of the washing water was below 100 ⁇ S/cm.
• the filtercake was dried at 120° C. with ingress of air over 16 h and subsequently calcined with ingress of air.
• the dried solid was heated initially to 120° C. at a heating rate of 1 K/min and kept at this temperature for 3 h. Subsequently, the solid was heated to 550° C. at a heating rate of 1 K/min and this temperature was maintained for 5 h.
• the analysis by x-ray diffraction showed that ZSM-12 had formed.
• the scanning electron microscopy analysis showed agglomerates having a diameter of about 0.8 ⁇ m which had formed from small primary crystals, and the agglomerates exhibited a broccoli-like structure.
• Example 2 920 g of the zeolite ZSM-12 obtained in Example 1 were suspended in a solution of 349.60 g of NH 4 NO 3 in 4250.40 g of demineralized water and stirred for 2 h.
• the solid was removed by filtration and the filtercake washed four times with 500 ml each time of demineralized water. Subsequently, the washed filtercake was slurried again in a fresh solution of 349.60 g of NH 4 NO 3 in 4250.40 g of demineralized water and stirred for 2 h.
• the solid was again removed by filtration and washed with demineralized water until the conductivity of the washing water had fallen below 100 ⁇ S/cm.
• the filtercake was subsequently dried under air at 120° C. over 14 h and then calcined under air. To this end, the washed and dried filtercake was heated to 480° C. at a heating rate of 1° C./min and then kept at this temperature for 8 h.
• the catalyst had the chemical and physical properties reported in Table 2:
• Example 1 was repeated, except that colloidal silica was used instead of precipitated silica.
• the synthesis gel composition was selected as follows:
• a solid was obtained which, in addition to ZSM-12 zeolite, contained ZSM-5 zeolite in a content of 30%.
• the solid was analyzed by scanning electron microscopy. From the scanning electron micrographs, the average diameter of the ZSM-12 primary crystals was determined to be 50-70 nm.
• the primary crystals formed by combination of tightly packed, continuous agglomerates. The proportion of the continuous agglomerates in the total number of agglomerates was more than 20%.
• a ZSM-12 zeolite as described by S. Ernst, P. A. Jacobs, J. A. Martens, J. Weitkamp; Zeolites, 1987, Vol. 7, 458-62, was produced.
• the zeolite was produced using methyltriethylammonium bromide (MTEABr).
• MTEABr methyltriethylammonium bromide
• the zeolite powder had an SiO 2 /Al 2 O 3 ratio of 108. Scanning electron micrographs under 1980- to 20 000-fold magnification showed rice grain-shaped crystals having an average length of from 0.5 to 13 ⁇ m.
• the zeolite powder was converted to the acidic H + form by ion exchange with NH 4 NO 3 and subsequent calcination.
• the zeolites in the H form obtained in Examples 2 and 6 were each pressed to tablets without further additives with the aid of a Carver laboratory press at a pressure of 18 tonnes. These tablets were crushed and the granules of sieve fraction 0.5-1.0 mm were removed. These granules were covered with 0.5% by weight of platinum by impregnating with 30% H 2 PtCl 6 solution. The granule was subsequently dried at 120° C. for 16 h and then calcined at 450° C. for 5 h. The properties of the granules are compiled in Table 4.
• the platinum catalysts obtained according to Example 7 were tested in a microreactor with pure n-heptane.
• the test conditions were as follows:
• the reactor was started up as follows: First, air was introduced at atmospheric pressure at a rate of 33.33 ml/min, and then the reactor was heated from room temperature to 400° C. This temperature was maintained for 1 h and then the temperature was lowered from 400° C. to 250° C. The air stream was then interrupted and replaced by a nitrogen stream (33.33 ml/min) for 30 min. The nitrogen stream was finally replaced by a hydrogen stream (33.33 ml/min) for 30 min. The pressure was then increased to 20 bar of H 2 , and then pure n-heptane was introduced and the product stream was analyzed by gas chromatography. The peak areas of all C1 to C7 components were measured every 30 min.
• i(so)-heptanes e.g. methylhexanes, dimethylpentanes, etc.
• the inventive catalyst exhibited steady state conversion and yield of 40% at virtually 100% selectivity. Cracking of the n-heptane to smaller molecules only took place in small fractions.
• the comparative catalyst exhibits no significant conversion of n-heptane at 250° C.
• the inventive catalyst exhibits a higher activity and converts n-heptane with very high selectivity even at low temperatures.
• Example 1 was repeated, except that the composition of the synthesis gel was adjusted to the following ratio:
• the crystallization time was increased to 175 hours. Otherwise, the process procedure corresponded to the sequence described in Example 1.
• a crystalline solid was obtained which was composed of ZSM-12.
• the solid was analyzed by scanning electron microscopy.
• the scanning electron micrograph reveals agglomerates which have a broccoli-like structure (open agglomerates).
• the proportion of closed agglomerates in the total number of agglomerates is less than 10%, while the open agglomerates correspond to a proportion of more than 90%.
• the platinum catalysts obtained according to Example 7 were tested in a microreactor with pure n-octane.
• the test conditions were as follows:
• Reactor diameter 8 mm
• Catalyst weight 2.0 g
• Catalyst size sieve fraction of the granulated material of from 0.5 to 1.0 mm Pressure: 20 bar Temperature: 245-250° C.
• WHSV 2.25 h ⁇ 1 Molar H 2 :n-heptane 1.3:1 ratio:
• the reactor was started up as follows: First, air was introduced at atmospheric pressure at a rate of 33.33 ml/min, and then the reactor was heated from room temperature to 400° C. This temperature was maintained for 1 h and then the temperature was lowered from 400° C. to 250° C. The air stream was then interrupted and replaced by a nitrogen stream (33.33 ml/min) for 30 min. The nitrogen stream was subsequently replaced by a hydrogen stream (33.33 ml/min) for 30 min. The pressure was then increased to 20 bar of H 2 , and then pure n-octane was introduced and the product stream was analyzed by gas chromatography.
• the catalyst was tested in the microreactor for 110 hours, in the course of which the activity and the selectivity were determined at 245 and 250° C.
• the inventive catalyst (Example 7 in conjunction with Example 2) showed an extremely high conversion rate of more than 85% and a selectivity after 10 hours of 80% at 250° C. At 245° C., the conversion was 70% and the selectivity 85%.
• Example 7 in conjunction with Example 6
• Example 7 exhibited a considerably lower selectivity and conversion rate.
• the loose structure and thus the high fraction of cavities between the primary crystals is shown in the mercury porosimetry in the range of pore radii of from 1.9 to 100 nm.
• the calcined inventive zeolite from Examples 1 and 9 exhibits a specific volume of from about 110 to 125 mm 3 /g in mercury porosimetry in the range from 4 to 10 nm.
• the calcined comparative example ZSM-12 zeolite, produced using colloidal silica, Example 5
• the inventive zeolites of Examples 1 and 9 have a specific volume of from 300 to 400 mm 3 /g.
• the zeolite from Example 5, employed for comparison exhibits a specific volume of 41 mm 3 /g in the range from 10 to 100 nm.
• the zeolites obtained in Examples 1, 5 and 9 were analyzed for their pore radius distribution by nitrogen porosimetry to DIN 66134.
• the experimental conditions were selected as follows according to the manufacturer's instructions and the evaluation was carried out by the method of “Dollim./Heal”.
• Examples 1 and 9 In agreement with the mercury porosimetry, the differences between the inventive zeolite (Examples 1 and 9) and Example 5 become clear in the pore radius range of 30-200 ⁇ in particular.
• the calcined inventive zeolite In nitrogen porosimetry in the range of 30-200 ⁇ , the calcined inventive zeolite exhibits a specific volume in the range of about 0.18-0.21 cm 3 /g.
• Example 5 employed as a comparison a specific volume of only 0.014 cm 3 /g was found in this range, which means that the zeolite for Example 5 exhibits a distinctly smaller fraction of cavities between the primary crystals.

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