Microporous crystalline silicoaluminophosphates: Effect of synthesis conditions on the physicochemical and catalytic properties in the reaction of methanol to C2-C4 olefins conversion

Knyazeva, E. E.; Коннов, С. В.; Shutkina, O. V.; Dobryakova, I. V.; Пономарева, О. А.; Ivanova, I. I.

doi:10.1134/s0965544114040069

Cited by 10 publications

(28 citation statements)

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“…SAPO-18 has been tested as a catalyst in the MTO reaction and was shown to have an improved lifetime as compared to SAPO-34 due to the lower density and lower strength of the Brønsted acid sites. [19,20,21] However, another study showed that when different SAPO-18 catalysts were prepared with different silicon content, the catalysts with higher silicon content showed an improved lifetime. [22] The conversion over SAPO-18 was shown to increase as the silicon content and acid site density increased.…”

Section: Introductionmentioning

confidence: 91%

CHA/AEI intergrowth materials as catalysts for the Methanol-to-Olefins process

Smith

Svelle

Campo

et al. 2015

Applied Catalysis A: General

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Section: Introductionmentioning

confidence: 91%

CHA/AEI intergrowth materials as catalysts for the Methanol-to-Olefins process

Smith

Svelle

Campo

et al. 2015

Applied Catalysis A: General

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“…As it has been shown in [11], the amount of the template in the silicoaluminophosphate structure after synthesis can serve as a quantitative characteristic of high crystallinity of these materials. The data pre sented in Table 1 indicate that, independently of the temperature and duration of the synthesis, the amounts of the template in the samples are very close and differ by no more than 4%.…”

Section: Resultsmentioning

confidence: 99%

Methanol to olefins conversion over silicoaluminophosphates with AEI structure: Effect of the active site type

et al. 2016

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Effect of the type of active site on the catalytic properties of microporous crystalline silicoalumi nophosphates with AEI structure synthesized at 150, 170, and 190°C has been investigated. The state of the active site was changed by varying the catalyst synthesis conditions. It has been established that during the synthesis of silicoaluminophosphates with the AEI structure from the reaction mixture of the same composi tion, an increase in the temperature and crystallization time leads to an increase of the silicon content and crystal size growth. The observed changes in the physicochemical properties are accompanied by the change of the silicon state in the structure of silicoaluminophosphates with the predominant formation of silicon "islands" via the SM3 mechanism. According to 29 Si NMR data, the formation of active sites of silicoalumi nophosphates via the SM2 mechanism in the form of isolated silicon atoms in the structure is also observed for these materials. The presence of such sites, along with the morphological features of the crystals, deter mines the unusual catalytic properties of silicoaluminophosphate with AEI structure in MTO process, which are a high ethylene yield up to 41 wt % at an ethylene : propylene molar ratio of 1 : 6.

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“…Silicoaluminophosphate SAPO-34 was prepared by the hydrothermal synthesis in an autoclave, rotated at a speed of 5 rpm, from the reaction mixture of Al 2 O 3 /2 P 2 O 5 /0.6 SiO 2 /4 TEAOH/70 H 2 O molar composition for 25 h at 190 °C. 31 The reactants were aluminum isopropoxide, silica sol (40 wt %), phosphoric acid (85 wt %), and tetraethylammonium hydroxide (35% aqueous solution). After crystallization, the product was separated from the liquid phase by centrifugation, washed, dried at 70 °C for 12 h, and calcined at 600 °C for 6 h in a dry-air stream.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of Zeolite Acidity by ³¹P MAS NMR Spectroscopy of Adsorbed Phosphine Oxides: Quantitative or Not?

et al. 2022

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31 P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy of adsorbed alkyl-substituted phosphine oxides has witnessed tremendous progress during the last years and has become one of the most informative and sensitive methods of zeolite acidity investigation. However, quantitative evaluation of the number of sites is still a challenge. This study clarifies the main origin of errors occurring during NMR experiments, introduces the appropriate standards (both internal and external), and determines the relaxation parameters and the conditions for the acquisition and integration of spectra. As a result, a methodology for the quantitative measurement of the content of Brønsted and Lewis sites and the amount of internal and external silanol groups is established. The application of probe molecules of different sizes (namely, trimethylphosphine oxide (TMPO), tri- n -butylphosphine oxide (TBPO), and tri- n -octylphosphine oxide (TOPO)) is shown to be a good tool for distinguishing between the active sites inside the zeolite pores, mesopores, and on the outer crystal surface. The methodology proposed is verified on BEA zeolites different in composition, texture, and morphology.

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Microporous crystalline silicoaluminophosphates: Effect of synthesis conditions on the physicochemical and catalytic properties in the reaction of methanol to C2-C4 olefins conversion

Cited by 10 publications

References 11 publications

CHA/AEI intergrowth materials as catalysts for the Methanol-to-Olefins process

CHA/AEI intergrowth materials as catalysts for the Methanol-to-Olefins process

Methanol to olefins conversion over silicoaluminophosphates with AEI structure: Effect of the active site type

Evaluation of Zeolite Acidity by ³¹P MAS NMR Spectroscopy of Adsorbed Phosphine Oxides: Quantitative or Not?

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Microporous crystalline silicoaluminophosphates: Effect of synthesis conditions on the physicochemical and catalytic properties in the reaction of methanol to C2-C4 olefins conversion

Cited by 10 publications

References 11 publications

CHA/AEI intergrowth materials as catalysts for the Methanol-to-Olefins process

CHA/AEI intergrowth materials as catalysts for the Methanol-to-Olefins process

Methanol to olefins conversion over silicoaluminophosphates with AEI structure: Effect of the active site type

Evaluation of Zeolite Acidity by 31P MAS NMR Spectroscopy of Adsorbed Phosphine Oxides: Quantitative or Not?

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Evaluation of Zeolite Acidity by ³¹P MAS NMR Spectroscopy of Adsorbed Phosphine Oxides: Quantitative or Not?