EP2158187A2 - Procédé de fabrication de mélamine - Google Patents

Procédé de fabrication de mélamine

Info

Publication number
EP2158187A2
EP2158187A2 EP08759828A EP08759828A EP2158187A2 EP 2158187 A2 EP2158187 A2 EP 2158187A2 EP 08759828 A EP08759828 A EP 08759828A EP 08759828 A EP08759828 A EP 08759828A EP 2158187 A2 EP2158187 A2 EP 2158187A2
Authority
EP
European Patent Office
Prior art keywords
catalyst
melamine
zeolite
weight
ppm
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08759828A
Other languages
German (de)
English (en)
Inventor
Christian Kuhrs
Andreas Kern
Tilo John
Wolfgang Steiner
Heiko Maas
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF SE
Original Assignee
BASF SE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BASF SE filed Critical BASF SE
Priority to EP08759828A priority Critical patent/EP2158187A2/fr
Publication of EP2158187A2 publication Critical patent/EP2158187A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
    • C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
    • C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
    • C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
    • C07D251/40—Nitrogen atoms
    • C07D251/54—Three nitrogen atoms
    • C07D251/56—Preparation of melamine
    • C07D251/60—Preparation of melamine from urea or from carbon dioxide and ammonia

Definitions

  • the invention relates to a process for the preparation of melamine by thermal decomposition of urea and catalytic reaction of the resulting isocyanic acid and the use of a specific catalyst in such a process.
  • melamine resins by reaction with carbonyl-containing compounds.
  • the resins are used, inter alia, as plastics and in paints and varnishes.
  • the production of melamine by decomposition of urea is a known reaction used by the chemical industry in several variants. In principle, a distinction is made between the high-pressure and the low-pressure method.
  • the high pressure process is carried out at pressures of> about 80 bar (abs.) And temperatures> 370 0 C, wherein the melamine synthesis takes place in a non-catalytic manner.
  • the low pressure process is carried out at pressures of about 1 to 10 bar (abs.) And temperatures of 370 to 430 0 C with catalysis.
  • the reaction takes place in two steps. In the first, endothermic step, urea decomposes into ammonia and isocyanic acid, which in the second, exothermic step trimerizes to melamine with the release of CO 2 .
  • the following equations reflect the individual reactions.
  • the DSM Stamicarbon process is a one-step process that is carried out at about 7 bar (abs.).
  • the catalysts used are aluminum silicates or zeolite-containing catalysts which are used in a fluidized bed.
  • the fluidizing gas is pure ammonia, which is recovered from the workup stage.
  • the fluidized bed is also used, alumina or alumina / silica catalysts being used.
  • the gas used for the fluidized bed is the cycle-derived circulating gas containing NH 3 and CO 2 , which has previously been freed of impurities.
  • active catalysts for melamine synthesis can be obtained by mixing Al 2 O 3 with zeolites or zeolites with metal cations.
  • Zeolite-containing catalysts for melamine synthesis are also available from Albemarle Corporation (USA) under the designation CAMEL 25®.
  • the object of the invention is to provide a process with which high conversions and melamine yields can be achieved, in particular when using a mixture of ammonia and CO 2 as fluidizing gas.
  • the object is achieved by a process for the catalytic production of melamine by decomposition of urea on zeolite-containing catalysts which contain a low content of nickel and vanadium.
  • the invention therefore provides a process for the preparation of melamine by decomposition of urea using a catalyst, wherein the catalyst
  • zeolite a) 10 to 90% by weight of zeolite, b) 10 to 90% by weight of a matrix containing silica, alumina, silicon-aluminum oxides and / or clay minerals, and c) 0 to 10% by weight of additives
  • Another object of the invention is the use of said catalyst for the production of melamine.
  • the catalyst used according to the invention contains as main components zeolite, a matrix of silicon and / or aluminum oxide and / or clay minerals, and optionally additives.
  • the zeolite component (a) preferably contains synthetic zeolites of the faujasite type, more preferably Y and silicon-rich Y zeolites, optionally also in a mixture.
  • zeolites are used which have been subjected to ion exchange, ie the original sodium atoms are replaced by hydrogen and / or rare earth metals (SE) (H, SE or H, SE-Y zeolites).
  • SE rare earth metals
  • the sodium content (as Na 2 O) is generally ⁇ 1% by weight.
  • ammonium sulfate or rare earth chloride solutions are generally used for the H and SE form.
  • the NH 4 form generally obtainable via ion exchange with ammonium sulfate solutions, is heated to convert to the H form, whereby NH 3 escapes.
  • the proportion of rare earth metals is generally 0-20, preferably 0-15 wt .-%.
  • rare earth metals lanthanum (La), cerium (Ce), neodymium (Nd) and praseodymium (Pr) are preferable. Particularly preferred is a mixture of lanthanum and cerium with lower levels of neodymium and praseodymium.
  • the Si / Al ratio of the zeolite is generally between 2 and 8, preferably 3 and 6, more preferably about 5 for conventional Y zeolite and between 10 and 15, preferably 11 and 12 for silicon-rich Y zeolites (SR-Y).
  • the size of the unit cell is generally between 2.460 nm and 2.465 nm for the Y zeolites, and about 2.450 for silicon-rich Y zeolites.
  • the size of the zeolite crystals is generally 0.5 to 5 ⁇ m.
  • the zeolite component of the catalyst may also contain mixtures of different zeolites, for example a mixture of Y zeolite and silicon-rich Y zeolite or additions of ZSM-5 zeolite, mordenite, offretite or silicalite.
  • the proportion of zeolite in the catalyst is generally from 10 to 90 wt .-%, preferably 10 to 60 wt .-%, particularly preferably 12.5 to 50 wt .-%, most preferably 15 to 40 wt .-%.
  • the preparation of the zeolite component is carried out by known methods known to the person skilled in the art, as described, for example, in Atlas of Zeolite Structure Types, W.H. Meier and D.H. Olson, 3rd Ed. Butterworth-Heineman, 1992.
  • the zeolite component can also be formed in situ together with the matrix component.
  • the matrix component (b) contains silica, alumina, aluminosilicates and / or clay minerals. It is a porous, inorganic oxide matrix that bonds the other components, provides abrasion resistance and may even contribute to catalytic activity.
  • the matrix component (b) usually contains a synthetic fraction, such as amorphous silica, alumina or aluminosilicate, and a natural portion, usually one or more clay minerals. If the zeolite component is prepared in situ from calcined clay, the matrix component also usually contains calcined clay.
  • a synthetic fraction such as amorphous silica, alumina or aluminosilicate
  • a natural portion usually one or more clay minerals. If the zeolite component is prepared in situ from calcined clay, the matrix component also usually contains calcined clay.
  • the matrix optionally contains boehmite, pseudo-boehmite, diaspore, ⁇ , ⁇ , ⁇ , ⁇ , ⁇ and p alumina or aluminum hydroxides, such as gibbsite, bayerite, nordstrandite and doilite.
  • the matrix component optionally contains one or more optionally modified clay minerals, such as kaolin, bentonite, attactogen, montmorillonite, hectorite and pyrophyllite.
  • the clay minerals are optionally subjected to mild base or acid treatment prior to use in the matrix to remove contaminants and interfering metal ions.
  • a calcination of the clay minerals for example, a conversion of kaolin into a spinel / mullite mixture by calcination at about 1000 0 C and subsequent leaching with base.
  • the catalysts according to the invention generally have a BET surface area of 50-800, preferably 100-600, particularly preferably 150-400 m 2 / g
  • amorphous silica containing matrix components usually additionally contain one or more natural clay minerals, and matrix components of modified, preferably calcined clay minerals.
  • the proportion of the matrix in the catalyst used according to the invention is generally from 10 to 90, preferably 40 to 90, particularly preferably 50 to 85 wt .-%.
  • the catalyst used according to the invention typically contains from 0 to 10% by weight of additives.
  • additives examples include inorganic oxides, such as magnesium oxide, mixed oxides of rare earth metals and spinels, for example cerium-doped spinels.
  • the catalysts used according to the invention are characterized by a low content of Ni and V.
  • the total content of these metals is ⁇ 500 ppm, preferably ⁇ 200 ppm, more preferably ⁇ 100 ppm, most preferably 0 to 50 ppm.
  • the catalyst is substantially free of Ni and V.
  • the preparation of the catalyst is carried out by known, familiar to those skilled in the process.
  • the catalyst can be produced in a known manner from an inorganic sol mixed with the zeolite component and further additives by drying, ion exchange, calcination and subsequent steam treatment.
  • the matrix and zeolite components of the catalyst generally have a different average pore size.
  • the mean pore size of the matrix is generally 0.4 to 500 nm, preferably 0.5 to 250 nm, more preferably 5 to 50 nm.
  • the average particle size d 50 of the catalyst is generally below 300 .mu.m, preferably between 10 and 200 .mu.m, more preferably between 40 and 100 .mu.m, wherein the fines (d ⁇ 10 microns) is preferably as low as possible.
  • catalysts may be subjected to the abrasion test described below. As a result, it provides an abrasion rate which describes the strength of the particles.
  • a precisely weighed sample of the catalyst (m 0 , catalyst), which is prescreened with a 45 micron sieve, placed on a 32 micron sieve with 192 mm diameter.
  • a slot nozzle (0.5 mm slit width) rotates at a distance of 10 mm at 32 rpm "1 , from which 100 m 3 -h " 1 nitrogen escapes at the speed of sound.
  • the catalyst which has been accelerated by the jet, bounces against a Plexiglas lid, which is 8 mm above the screen.
  • the sample material is subjected to intensive mechanical stress. The trial period is 3 hours.
  • the resulting abrasion comes out with the gas through the mesh.
  • the mass of the remaining particles is determined quantitatively at intervals of about 15 minutes by weighing.
  • the abrasion rate AR expressed in g-kg "1 -h " 1 , is calculated as the quotient of the mass loss within the last hour of the test m A b ⁇ eb [gh "1 ] and the mass of the catalyst remaining after the experiment m Ka taiysator trial end [kg]:
  • Suitable catalysts for fluidized bed processes have an abrasion rate of less than 60 g-kg "1 -h " 1 , preferably less than 30 g-kg "1 -h " 1 .
  • the abrasion rate of the catalyst is generally ⁇ 20 g / kgh, preferably ⁇ 15 g / kgh, more preferably ⁇ 10 g / kgh, especially 1-7 g / kgh
  • the catalyst belongs to the so-called Geldard group A (D. Kunii, A. Levenspiel, Fluidization Engineering, 2nd edition, Butterworth-Heinemann, 1991).
  • urea is thermally decomposed in a first step to form isocyanic acid and ammonia, and the isocyanic acid formed is subsequently trimerized catalytically with the release of CO 2 to form melamine.
  • Both reaction steps are preferably carried out in one reactor, but they can also be carried out in two separate reactors.
  • the process is preferably carried out as a fluidized bed process. It is in general at temperatures of 350 to 450 0 C, preferably 380 to 420 0 C, an absolute pressure of generally 1 to 15 bar, preferably 1 to 10 bar, in particular 1, 5 to 8 bar, a residence time over the Fluidized bed of 1 to 50 s, preferably 2 to 30 s and a catalyst loading of 20 to 700 kg urea / t (cat) • h, preferably 50 to 500 kg urea / t (cat) • h operated.
  • the fluidizing gas used is pure NH 3 or an NH 3 / CO 2 mixture, the mixture used in the latter case predominantly being the mixture formed during the synthesis.
  • the educt urea is preferably introduced into the reactor as a melt.
  • heat is supplied to the reaction mixture, preferably via heating coils in which a molten salt circulates.
  • Catalyst particles can be retained in the reactor by cyclone separators.
  • the formed in the synthesis, gaseous melamine is isolated from the fluidizing gas by quenching with aqueous mother liquor ("washing with water”) and subsequent crystallization or by cooling the reaction gases with cold reaction gas (sublimation).
  • the gas mixture can be cooled from the reactor into a first gas cooler to a temperature at which by-products (eg Meiern) crystallize and the precipitated by-products are deposited together with the catalyst dust contained in the gas stream in gas filters. Then the filtered gas stream in a crystallizer with process gas having a temperature of about 140 0 C, are mixed, wherein the melamine crystallized in a purity of at least 99.9%.
  • by-products eg Meiern
  • the melamine prepared in this way can generally be reacted directly without further purification steps, for example for the preparation of melamine resins by reaction with carbonyl compounds.
  • urea was converted to melamine at a temperature of about 400 ° C.
  • the amount of fluidizing gas (NH 3 / CO 2 ) was about 110 Nm 3 / h.
  • Catalyst 1 (Comparative Example 1) is a zeolite-containing, commercially available for melamine synthesis catalyst with a Ni / V content of 3900 ppm in the batch tested.
  • Catalyst 2 (Comparative Example 2) is a zeolite-free catalyst based on Si (VAI 2 Os having a Ni / V content below the detection limit which was 100 ppm (measurement method: X-ray fluorescence).
  • Catalyst 3 (Example 1) is a zeolite-containing catalyst according to the invention with a Ni / V content of ⁇ 100 ppm.
  • the zeolite-free catalyst shows a similar conversion as the catalyst of the invention, but has other disadvantages such as grain (“Geldart B” leads to poorer heat transfer coefficients and thus poorer heat transfer into the fluidized bed) and an unfavorable Abriebsindex.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Catalysts (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention concerne un procédé de fabrication de mélamine par décomposition d'urée au moyen d'un catalyseur, le catalyseur contenant a) 10 à 90 % en poids de zéolithes, b) 10 à 90 % en poids d'une matrice renfermant du dioxyde de silicium, de l'oxyde d'aluminium, des oxydes de silicium-aluminium et/ou des minérais argileux, et c) 0 à 10 % en poids d'additifs, la teneur totale en nickel et vanadium dans le catalyseur étant inférieure à 500 ppm.
EP08759828A 2007-06-14 2008-05-21 Procédé de fabrication de mélamine Withdrawn EP2158187A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP08759828A EP2158187A2 (fr) 2007-06-14 2008-05-21 Procédé de fabrication de mélamine

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP07110305 2007-06-14
EP08759828A EP2158187A2 (fr) 2007-06-14 2008-05-21 Procédé de fabrication de mélamine
PCT/EP2008/056223 WO2008151907A2 (fr) 2007-06-14 2008-05-21 Procédé de fabrication de mélamine

Publications (1)

Publication Number Publication Date
EP2158187A2 true EP2158187A2 (fr) 2010-03-03

Family

ID=39967208

Family Applications (1)

Application Number Title Priority Date Filing Date
EP08759828A Withdrawn EP2158187A2 (fr) 2007-06-14 2008-05-21 Procédé de fabrication de mélamine

Country Status (7)

Country Link
US (1) US8415265B2 (fr)
EP (1) EP2158187A2 (fr)
AR (1) AR067019A1 (fr)
CL (1) CL2008001772A1 (fr)
RU (1) RU2535350C2 (fr)
UA (1) UA102521C2 (fr)
WO (1) WO2008151907A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106902799A (zh) * 2017-02-17 2017-06-30 鲁西催化剂有限公司 一种合成高铝硅胶的制备方法

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2832887A1 (fr) 2011-04-11 2012-10-18 ADA-ES, Inc. Methode par lit fluidise et systeme de capture de composant gazeux
WO2014047354A1 (fr) 2012-09-20 2014-03-27 ADA-ES, Inc. Procédé et système de récupération de sites fonctionnels sur un sorbant contaminé par des sels thermostables
CN114887657B (zh) * 2022-06-10 2024-01-26 宁波中科远东催化工程技术有限公司 一种合成三聚氰胺的催化剂及其制备方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL9002606A (nl) * 1990-11-29 1992-06-16 Stamicarbon Proces voor de bereiding van melamine uit ureum.
KR20010070002A (ko) * 1999-07-29 2001-07-25 고오사이 아끼오 내산성 촉매 시트 및 이의 제조방법
ATE477247T1 (de) * 2003-01-17 2010-08-15 Basf Se Zweistufiger reaktor für die melaminsynthese
EP2072504A1 (fr) * 2007-12-20 2009-06-24 DSMIP Assets B.V. Procédé de préparation de mélamine
RU2361669C1 (ru) * 2007-12-26 2009-07-20 Открытое акционерное общество "Новомосковский институт азотной промышленности" Способ получения катализатора для синтеза меламина из карбамида

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2008151907A2 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106902799A (zh) * 2017-02-17 2017-06-30 鲁西催化剂有限公司 一种合成高铝硅胶的制备方法
CN106902799B (zh) * 2017-02-17 2020-03-27 鲁西催化剂有限公司 一种合成高铝硅胶的制备方法

Also Published As

Publication number Publication date
CL2008001772A1 (es) 2009-09-25
US20100184976A1 (en) 2010-07-22
WO2008151907A3 (fr) 2009-04-09
WO2008151907A2 (fr) 2008-12-18
US8415265B2 (en) 2013-04-09
AR067019A1 (es) 2009-09-30
RU2535350C2 (ru) 2014-12-10
UA102521C2 (ru) 2013-07-25
RU2010100912A (ru) 2011-07-20

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