The kinetics and mechanisms of the crystallisation of microporous materials

Francis, Robin J.; O’Hare, Dermot

doi:10.1039/a802330a

Cited by 157 publications

(127 citation statements)

References 114 publications

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“…influence the product formation. Despite several efforts undertaken by different groups we are far from a deeper understanding of the reaction mechanisms occurring under solvothermal conditions [26]. The following example should illustrate the main problems of the solvothermal approach: syntheses performed with Sb, S, Ni and diethylenetriamine as structure director leads to a couple of compounds like [Ni(dien) 2 ] 2 Sb 4 S 8 [27], [Ni(dien) 2 ] 2 Sb 4 S 9 [28] or [Ni(dien) 2 ] 3 (Sb 3 S 6 ) 2 [29] under almost identical conditions.…”

Section: Introductionmentioning

confidence: 99%

Solvothermal Syntheses of Two New Thiostannates and an In‐Situ Energy Dispersive X‐ray Scattering Study of Their Formation

2009

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Two new thiostannates (DBNH) 2 Sn 3 S 6 (1) and (DBNH) 2 Cu 6 Sn 2 S 8 (2) were synthesized under solvothermal conditions applying Cu, Sn, S and DBN (DBN = 1,5-diazabicyclo[4.3.0]non-7-ene). Compound 1 is a rare example of a mixed-valent thiostannate. The Sn(II) species appears in the rare trigonal-pyramidal environment whereas Sn(IV) is in a tetrahedral coordination. The chain-anion is composed of alternating Sn 3 S 4 semi-cubes and Sn 2 S 2 rings. The structure of 2 consists of undulated anionic layers and amine molecules between the layers. The layers may be viewed as a heteroatom 6 3 graphene layer constructed by condensed CuS 3 triangles and SnS 4 tetrahedra. The two thiostannates coexist which was investigated with in-situ energy dispersive X-ray scattering under real solvothermal conditions. Prior to the formation of 1 and 2 a crystalline intermediate appears which disappears after 60 min.Then reflections of 2 start to grow and reflections of 1 occur some time later. The appearance of a thiostannate(IV) followed by the crystallization of a mixed-valent thiostannate(II,IV) suggests complex redox reactions occurring under the solvothermal conditions. Syntheses without Cu in the reaction slurry lead to the formation of 1 within a very short time. The results of the in-situ studies clearly indicate that the presence of Cu species in solution retards the nucleation and crystallization of 1. The crystalline intermediate was quenched with ex-situ experiments. All syntheses performed with this intermediate do not lead to the crystallization of 1 or 2, i.e., there is no direct relation between these three crystalline compounds. The spectroscopic and thermal properties of 1 and 2 are also discussed.

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Section: Introductionmentioning

confidence: 99%

Solvothermal Syntheses of Two New Thiostannates and an In‐Situ Energy Dispersive X‐ray Scattering Study of Their Formation

2009

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“…[1][2][3][4] This process is a successive process, so it is paramount to study the mechanism under actual synthetic conditions. [7] However, only a few studies on zeolite A have been performed under in situ conditions. [6c,g-i] UV-Raman spectroscopy has been demonstrated to be a powerful tool for the characterization of zeolites with the advantage of avoiding fluorescence, [8] increasing sensitivity, [8] investigating both liquid and solid phases, [6e, 9] and monitoring the evolution of precursors and the formation of zeolite crystal particles.…”

mentioning

confidence: 99%

UV–Raman and NMR Spectroscopic Studies on the Crystallization of Zeolite A and a New Synthetic Route

Ren

Fan

et al. 2011

Chemistry A European J

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Lithiumzirconimidate (siehe Struktur) wurden nach der Deprotonierung von Zirconiummethylamid‐Komplexen oder der Addition von Methyllithium an Imidozirconium‐Komplexe isoliert. Quantitative Untersuchungen zur Säurestärke dieser konjugierten Basen von Zirconiumamidkomplexen ergaben, dass kinetische wie thermodynamische Größen des Protonenaustauschs von den weiteren Liganden am Zirconiumzentrum abhängen.

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“…2,3 Control of pore geometry and diameter are key to many of these applications, especially in the case of those that rely on size or shape selectivity and ready access to pore system. The synthesis of ALPO molecular sieves, as for zeolites, involves the use of organic agents as 'templates'.…”

mentioning

confidence: 99%

Tuning the pore size from micro- to meso-porous in thermally stable aluminophosphates

Cabrera¹,

Haskouri²,

Guillem³

et al. 1999

Chem. Commun.

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Thermally stable porous aluminophosphates (ICMUV-3) with P/Al molar ratios in the range 0.15 @ P/Al @ 0.75 and showing continuously adjustable pore sizes from 13 to 37 Å have been prepared through a surfactant-assisted procedure without changing the surfactant length and/or addition of organic expansors.Since the discovery in 1982 of three-dimensional aluminium phosphates (ALPOs), 1 their chemistry has aroused great interest mainly due to the attainment of microporous structures showing a broad range of physicochemical properties of potential application in fields such as catalysis or molecular sieving. 2,3 Control of pore geometry and diameter are key to many of these applications, especially in the case of those that rely on size or shape selectivity and ready access to pore system. The synthesis of ALPO molecular sieves, as for zeolites, involves the use of organic agents as 'templates'. 4 In this sense, the synthetic strategy developed by Mobil scientists to obtain mesoporous silicas by use of micellar aggregates of surfactants as 'templates', 5 was also seen as very promising for the preparation of aluminophosphates. Thus, Stucky and coworkers 6 were the first to extend the surfactant templating strategy to the synthesis of non-silica-based mesostructures, mainly metal oxides. However, in the case of the ALPO system this method has not been as fruitful as for silica-based materials. Although lamellar 7 and hexagonal MCM-41-type mesostructured ALPOs 8,9 have been prepared through surfactant-assisted synthetic strategies, the preparation of the corresponding mesoporous materials was not possible because their mesostructure collapsed upon calcination during surfactant removal. More recently, the preparation of two thermally stable mesoporous ALPOs using cationic surfactants has been described: Kevan and coworkers 10,11 have reported the synthesis of non-ideal mesoporous aluminophosphates (0.16 @ P/Al @ 0.60) with a constant pore size around 35 Å, and Kuroda and coworkers 12,13 have described the isolation of mesoporous ALPO's showing pore diameters modulated in the range 18-39 Å by changing the chain lengths of the surfactants and using organic cosurfactants as pore expansors.We report here, a novel method to prepare thermally stable mesoporous aluminophosphates, denoted ICMUV-3, allowing a continuous adjustment of the pore sizes simply by regulation of both the P/Al molar ratio and the water content in the mothersolution.Mesoporous ICMUV-3 materials have been prepared using cetyltrimethylammonium bromide (CTABr) as surfactant structural directing agent in an aqueous TEA (triethanolamine) medium with a molar ratio in the starting solution Al : xP : 0.3C-TABr : 3.8TEA : yH 2 O, (x = 0.12-1.5, y = 131-185). In a typical sample preparation, Al(OBu s ) 3 (5.1 ml, 0.02 mol) was slowly added to liquid TEA (10 ml; 0.075 mol) and heated at 160°C. After 30 min, the solution was cooled at 120°C and 2.1 g of CTABr (0.006 mol) added. Then, it was cooled at room temperature and mixed with 43 ml (2.4 mol) of distilled water...

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The kinetics and mechanisms of the crystallisation of microporous materials

Cited by 157 publications

References 114 publications

Solvothermal Syntheses of Two New Thiostannates and an In‐Situ Energy Dispersive X‐ray Scattering Study of Their Formation

Solvothermal Syntheses of Two New Thiostannates and an In‐Situ Energy Dispersive X‐ray Scattering Study of Their Formation

UV–Raman and NMR Spectroscopic Studies on the Crystallization of Zeolite A and a New Synthetic Route

Tuning the pore size from micro- to meso-porous in thermally stable aluminophosphates

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