The crystal quality and structure of AM6

Rumeysa Tekin, Juliusz Warzywoda, Albert Sacco

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Microporous vanadosilicate AM-6, isostructural with titanosilicate ETS-10, is a novel promising material in the traditional zeolite applications such as catalysis, photocatalysis, gas separation, sorption and the monatomic –O-V-O-V-O chains have shown potential for use in quantum wire application. High purity vanadosilicate AM-6 products with different crystal quality (disorder, or average length of the V-O-V chains in the AM-6 framework) and sizes in the range of ~50 nm to ~6 μm were hydrothermally synthesized at 448-503 K using tetramethylammonium (TMA+) ions. The combined SEM, EDX, XRD, Raman, TGA, XPS, and nitrogen adsorption isotherm data showed that by treating these as-synthesized materials in gaseous ammonia at 673 K it is possible to completely remove TMA+ ions from the AM-6 pores without adversely affecting product crystallinity and the micropore structure of AM-6, and with only minimal degradation of crystal quality of the resulting products. However, the success in a complete removal of TMA+ ions without affecting other crystalochemical characteristics of the product depended on its initial crystal quality. TMA+ ions could not be completely removed from the lowest crystal quality product (FWHM=20.3 cm-1) without completely decomposing the V-O-V chains. The intermediate crystal quality product (FWHM=15.0 cm-1) could be successfully ammonia-treated only at 673 K to remove TMA+ ions, but higher temperatures resulted in a complete decomposition of the V-O-V chains. The highest crystal quality product (FWHM=12.7 cm-1) retained the integrity of V-O-V chains as well as the long range order and the micropore structure when ammonia-treated up to 748 K.

Original languageEnglish
Title of host publicationMaterials Engineering and Sciences Division 2017 - Core Programming Area at the 2017 AIChE Annual Meeting
PublisherAIChE
Pages107-148
Number of pages42
ISBN (Electronic)9781510857971
StatePublished - 2017
EventMaterials Engineering and Sciences Division 2017 - Core Programming Area at the 2017 AIChE Annual Meeting - Minneapolis, United States
Duration: Oct 29 2017Nov 3 2017

Publication series

NameMaterials Engineering and Sciences Division 2017 - Core Programming Area at the 2017 AIChE Annual Meeting
Volume1

Conference

ConferenceMaterials Engineering and Sciences Division 2017 - Core Programming Area at the 2017 AIChE Annual Meeting
CountryUnited States
CityMinneapolis
Period10/29/1711/3/17

Keywords

  • AM-6
  • Crystal quality
  • Gaseous ammonia treatment
  • Hydrothermal synthesis
  • Nanocrystals
  • Vanadosilicates

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