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ATN‐type FeAPO‐39 molecular sieves with high iron content has been successfully synthesized under non‐solvent conditions, which is the first example of iron‐incorporated aluminophosphate with the ATN‐zeotype structure. The optimum synthetic conditions of this material were refined. It was found that the following synthetic conditions, i.e. a low P2O5/Al2O3 ratio, a high DPA/Al2O3 ratio (DPA: di‐n‐propylamine) and an elevated crystallization temperature, seemed to be more favorable for the non‐solvent synthesis of ATN phase. The composition and structural characteristics of resultant relatively pure FeAPO‐39 molecular sieves were intensively studied by XRD, FT‐IR, TG‐DTA, CHN elemental analysis, ICP‐AES, SEM, TEM, N2 physisorption, UV/Vis diffuse reflectance spectroscopy and Mössbauer spectroscopy analyses. The iron content and zeolite yield of FeAPO‐39 material were found to be as high as 5.56 wt.‐% and 82.6 %, respectively. The results of FT‐IR, TG‐DTA and CHN elemental analysis indicate that DPA molecules may co‐direct the synthesis of ATN zeolites along with additional structure‐directing agent NH4+ ions resulting from iron source. Owing to the specific structure‐directing role provided by iron source, the synthetic strategy presented here may find a potential application in the non‐solvent synthesis of other aluminosilicate and aluminophosphate zeolites with novel frameworks. The incorporation of iron into the framework of ATN‐zeotype structure was achieved in non‐solvent system. DPA molecules and additional NH4+ ions resulting from iron compound act as the SDA. [ABSTRACT FROM AUTHOR]

Three iron-containing AlPO-5 molecular sieve catalysts (i.e. FeAlPO-5-Iono, FeAlPO-5-Hydro and FeAlPO-5-Imp) were prepared by ionothermal synthesis, direct hydrothermal synthesis and impregnation method, and characterized by various techniques. N adsorption/desorption measurements, together with the results of SEM and TEM, showed that FeAlPO-5-Iono was a new type of aluminophosphate molecular sieve with hierarchical micro- and meso-porous structure, whereas both FeAlPO-5-Hydro and FeAlPO-5-Imp were typical microporous materials. DR UV-Vis analysis suggested that the order of the amounts of isolated Fe species in these three samples was as follows: FeAlPO-5-Hydro > FeAlPO-5-Iono > FeAlPO-5-Imp. However, the order of their catalytic performances towards phenol hydroxylation was in opposition to that of the amounts of isolated Fe species. Detailed analysis revealed that it was textural properties of these catalysts that determined phenol conversion and dihydroxylbenzene selectivity. The catalyst-recycling tests suggested that extra-framework iron clusters were readily leached into the reaction system and had great influence on the hydroxylation of phenol. Due to the sole presence of isolated Fe species and enhanced mass transport of reactants and products to/from these active sites, FeAlPO-5-Hydro was found to have the best reusability among these catalysts. Graphical Abstract: [Figure not available: see fulltext.]. [ABSTRACT FROM AUTHOR]

HZSM-5 is a widely used catalyst for the conversion of methanol to aromatics (MTA), but its single micropore system often results in severe diffusion limitations, leading to the decrease of reaction rate and the change of selectivity to aromatics, as well as affecting the carbon deposition and catalyst deactivation. Thus, an ingenious protective desiliconization method with a mixed solution of sodium hydroxide and tetrapropylammonium hydroxide as a desiliconization agent was developed to create hierarchical porous systems without destruction of the main structure of the molecular sieve. Such modification leads to the greatly increased mesoporous volume from 0.12 to 0.38 cm3 g−1, and only slightly decreased microporous volume from 0.12 to 0.09 cm3 g−1. However, the desiliconization sharply increases the acidity of the catalyst (from 0.248 to 0.341 mmol g−1 for the strong acid sites), which may significantly affect the distribution of aromatics and accelerate the carbon deposition rate. Thus, the deposition of inert SiO 2 on the catalyst surface is subsequently carried out to passivate the surface acidity and adjust the orifice of the catalyst. Accordingly, a hierarchical porous HZSM-5 molecular sieve catalyst (Si@Z5-Na + TP) with suitable acidity is precisely prepared, which exhibits the high selectivity to benzene, toluene and xylenes (BTX) with the excellent anticoking ability in the MTA reaction. The selectivity to BTX in aromatics (63.32%) and the carbon deposition rate (0.91 mg g cat −1 h−1) over the Si@Z5-Na + TP catalyst are both much more superior than those over the parent HZSM-5 catalyst (47.5% and 2.23 mg g cat −1 h−1, respectively). A composite catalyst Si@Z5-Na + TP amalgamating with hierarchical porous system and suitable acidity was successfully fabricated by protective desiliconization and subsequent silanization modification, which exhibited high selectivity for benzene, toluene and xylenes (BTX) and excellent anticoking ability in the transformation reaction of methanol to aromatics (MTA). Image 1 • The hierarchical porous HZSM-5 with suitable acid content is designed precisely. • The mixed solution of NaOH and TPAOH was used as protective desiliconization agent. • The deposition of inert SiO 2 is then done to modify the surface acid density. • The designed catalyst exhibits high selectivity for BTX in the MTA reaction. • The catalyst also exhibits excellent anticoking ability in the MTA reaction. [ABSTRACT FROM AUTHOR]

AlPO 4 -5 aluminophosphate molecular sieve with AFI topology has been successfully synthesized by microwave irradiation under solvent-free conditions. The key influential factors controlling the crystallization of AFI structure were thoroughly investigated. The optimum synthetic conditions of this material are as follows: the initial composition is 1.0Al 2 O 3 : 3.0P 2 O 5 : 2.0HF: 8.0TEABr(tetraethylammonium bromide): 125C, aluminum isopropoxide is the best aluminum source, and activated carbon needs to be pretreated before used as the reaction medium and hard template. The resultant AlPO 4 -5 molecular sieves were characterized by X-ray diffraction (XRD), N 2 physisorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results reveal that the obtained samples exhibit hierarchically porous characteristic. [ABSTRACT FROM AUTHOR]

Abstract: SAPO-5 molecular sieve with AFI topology has been ionothermally synthesized by microwave irradiation and using eutectic mixture based on pentaerythritol and choline chloride as reaction medium. The resultant SAPO-5 molecular sieve was characterized by X-ray diffraction (XRD), 29Si magic-angle spinning nuclear magnetic resonance (29Si MAS-NMR), N2 physisorption, scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), and thermogravimetry–differential thermal analysis (TG–DTA). 29Si MAS-NMR showed that the incorporation of Si in the calcined sample was mainly by the SM3 mechanism. N2 physisorption measurements confirmed that the resulting SAPO-5 molecular sieve contained mesopores with a pore radius of about 3–30nm. CHN and TG–DTA analysis revealed that it was choline that directed the synthesis of SAPO-5. Moreover, the factors affecting the crystallization of SAPO-5 molecular sieve were investigated in detail. The results showed that P2O5/Al2O3 ratios, HF/Al2O3 ratios and reaction temperature had great impact on the crystallization of SAPO-5. [Copyright &y& Elsevier]

Abstract: FeAlPO-5 molecular sieve with AFI topology was ionothermally prepared under microwave irradiation in a three-component eutectic mixture and characterized by various techniques. N2 adsorption/desorption measurements implied that the resultant samples exhibited a mesopore characteristic. Electron spin resonance (ESR) and diffuse reflectance UV–Visible spectra (DR UV–Vis) results revealed that various iron species coexisted on the mesoporous FeAlPO-5 molecular sieve. CHN elemental analysis, thermogravimetry–differential thermal analysis (TG–DTA) and the results of Fourier transform infrared spectra (FT-IR) suggested that tetraethylammonium bromide acted as the structure-directing agent in the synthetic process of FeAlPO-5 molecular sieve. In addition, the factors affecting the crystallization of FeAlPO-5 molecular sieve were investigated in detail. Contrary to the effect of the composition of the eutectic mixture, the types of iron and aluminum sources, as well as the addition of water, did not have major influences on the phase selectivity of the crystallization reaction. Relatively low P2O5/Al2O3 ratio, the addition of appropriate amount of HF, a longer time and higher temperature favored the crystallization of FeAlPO-5 molecular sieve. [Copyright &y& Elsevier]

Although HZSM-5 zeolite is more and more widely used in petrochemical industry and other fields, its single narrow micropore system often leads to mass transfer issues during some types of catalytic reactions. In addition, dealumination in the presence of steam and coking due to the presence of strong acids sites are issues of aluminosilicate catalysts in general. In this work, a simple post-treatment method based on the traditional prepared HZSM-5 catalyst was proposed and an outlayer SiO 2 encapsulated Gd/HZSM-5 catalyst with hollow and hierarchical porous systems (Si@Gd/Z5-T) was obtained. This catalyst can overcome those defects for the traditional HZSM-5 mentioned above, such as, the outermost SiO 2 layer can protect the aluminum species in the framework of Gd/HZSM-5 and cover part of strong acid sites, and the hollow and hierarchical porous systems can minimize the mass transfer resistance, etc. The Si@Gd/Z5-T catalyst exhibited high selectivity of BTX (65.7%), especially xylene (39.7%), in the methanol to aromatics reaction (MTA) owing to the suitable acidity and optimized porous system. In addition, the Si@Gd/Z5-T catalyst possessed much better hydrothermal stability and the excellent anticoking ability in the MTA reaction as expected. Thus, this should be a general method for the modification of silica alumina molecular sieve catalysts to obtain the novel catalyst with hollow and hierarchical porous systems, adjustable acidity and high hydrothermal stability. An outlayer SiO 2 encapsulated Gd/HZSM-5 catalyst with hollow and hierarchical porous systems (Si@Gd/Z5-T) was prepared through a simple post-treatment method, which exhibited the high selectivity of BTX (65.7%) especially xylene (39.7%) in the methanol to aromatics reaction. [Display omitted] • An outlayer SiO 2 encapsulated Gd/HZSM-5 with hollow structure was prepared. • This catalyst can overcome the defects for the traditional HZSM-5 catalyst. • The catalyst exhibited high selectivity of BTX (65.7%) in the MTA reaction. • The catalyst possessed excellent hydrothermal stability and anticoking ability. [ABSTRACT FROM AUTHOR]

The FeAPO-44 molecular sieve with CHA-type structure has been synthesized under solvent-free conditions. This is the first case that this material was successfully prepared by this novel solvent-free method. Its optimal synthesis conditions were refined. The results show that proper P 2 O 5 /Al 2 O 3 ratio, a lower SDA/Al 2 O 3 ratio (SDA: cyclohexylamine) and relatively mild crystallization temperature are more beneficial to the synthesis of pure CHA phase. The structural and compositional characteristics of the relatively pure FeAPO-44 zeolite were studied in depth by XRD, TG-DSC, CHN element analysis, EDS, SEM and N 2 physisorption. According to the CHN element analysis, EDS and TG-DSC measurements, the approximate chemical formula of the synthesized sample SDA/Al-1.4 was determined. The catalytic performances of selected samples were investigated in the methanol-to-olefins reaction. The present results imply that many other zeolite topologies may be conveniently prepared by this solvent-free route. [Display omitted] • FeAPO-44 molecular sieve with CHA topology was firstly prepared by a novel solvent-free method. • The ideal chemical composition of the FeAPO-44 molecular sieve was determined. • A facile preparation procedure was developed to synthesize CHA-type material. [ABSTRACT FROM AUTHOR]