[M]-CAL-2: MeAPSO-34-like molecular sieves using a lamellar aluminophosphate as precursor

Comparison of the structure-directing effect of ephedrine and pseudoephedrine during crystallization of nanoporous aluminophosphates

“…Our combined experimental and computational study has shown a notably different structure-directing behavior of the two isomers, ephedrine and pseudoephedrine, during crystallization of AFI-based nanoporous aluminophosphates. Our previous work [22] showed a higher supramolecular aggregation of ephedrine compared to that of dimensionalities is very common [28]; indeed, in occasions some of these materials can be transformed into 3D nanoporous aluminophosphates [29,30]; however, calcination of our layered material gives trydimite as a result, and hence has no major interest. Certain layered materials prepared with aromatic molecules have in fact an organic bilayer in the interlaminar space [31,32] similar to that proposed for our layered material.…”

Incorporation of mixed metals into SAPO-34 frameworks by the dry-gel conversion method using mixed templates: investigating catalysts characterisation and performance

“…The substitution of transition metal ions (TMI) into the structure of the SAPO-34, because the MÀO (M D Mn or Ni) bond lengths (1.9À2.0 A ) are longer than the typical TÀO (T D Si, Al or P) bond of SAPO (1.5À1.7 A ), affects the crystallinity of particles. [15] Furthermore, the lower crystallinity was observed for the NiAPSO-34 samples. The crystallinity of S-5 (which Ni and Mn are incorporated into SAPO-34 simultaneously) is higher than the crystallinity of S-1 and S-2 samples.…”

Physicochemical characterization to assess Ni and Zn incorporation into zeotype SAPO-34 nanoparticles synthesized with different mixing methods through ultrasound-promoted crystallization

“…5(a)), but leads to the formation of smaller aggregates with sizes ranging between 0.9 and 1.6 mm, presumably due to an increase in the number of nuclei. 28,55 As depicted in Fig. 5(b), when the nickel content in the synthesis gel increases from 0.05 to 0.1, the smaller agglomerated particles with less uniform morphology compared with sample Ni-4 are obtained.…”

“…It is expected that lattice expansions should be observed when metal ions substitute for Al 3+ and/or P 5+ , which is plausibly related to the reason that the radii of T (T ¼ Si, Al, or P) and T-O bond lengths of silicoaluminophosphates (1.5-1.7Å) are typically smaller than the radii of M (M ¼ metal ions such as Ni or Zn) and M-O bond lengths (1.9-2.0Å). 27,55 Compared with SAPO-34 samples, the XRD patterns of Niand Zn-containing SAPO-34 crystals illustrate a slight shi towards the lower angle in the peak positions. As mentioned by Zhang et al, 27 such shi supports the occurrence of true isomorphous substitution of metal ions, due to the increase in the interplanar spacing and thus lattice parameters.…”

“…Furthermore, distortions in the crystalline network can be explained by taking into account the isomorphous substitution of the metals into the SAPO-34 framework, because the difference between the bond lengths of the M-O (M ¼ Zn or Ni) and the typical T-O (T ¼ Si, Al or P) impresses the bond angles between the tetrahedral construction units (MO 4 and TO 4 ), creating distortions along the crystalline network and thus, lowering the crystallinity of materials. 21,28,55 The effect of the applied crystallization methods was evaluated by comparing the samples S-1, Ni-4, and Zn-4 synthesized sonochemically and samples S-2, Ni-8, and Zn-8 obtained by conventional hydrothermal crystallization. Although the XRD patterns of samples S-2, Ni-8, and Zn-8 (depicted in Fig.…”