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NOVEL WAYS OF SYNTHESIZING ZEOLITE A

Brar, Tenjinder
http://rave.ohiolink.edu/etdc/view?acc_num=ucin973702236

Abstract Details

2000, MS, University of Cincinnati, Engineering : Chemical Engineering.
In the present work, we have explored numerous ways to reduce the mean particle size of zeolite A, keeping the economic imperatives in mind. In addition to this, efforts were directed towards reducing the crystallization time and having a more narrow particle size distribution. Besides the study of more conventional parameters such as temperature, alkalinity, water content etc., the effect of using microwaves, centrifuge and ultrasonication was also explored. It was expected that the highly localized temperatures of thousands of degree Kelvin and pressures of hundreds of atmospheres produced by ultrasonication might disrupt the nucleation process in a manner so as to lead to smaller crystals. Surprisingly, it was found that the application of ultrasonication does not lead to any decrease in the particle size. Both ultrasonication and stirring being different forms of agitation, one expected to find crystals with similar morphology in the aforementioned two cases. However, the crystal morphologies obtained in the two cases are completely different which was rather unexpected. Subjecting the zeolite batch to short periods of microwave radiation leads to a narrow particle size distribution with small crystal size. A direct correlation between the nominal SiO2/Al2O3 ratio and the particle size was observed. Decreasing SiO2/Al2O3 ratios lead to a narrower particle size distribution. Agitation was noticed to have an adverse effect as regards the final objective of obtaining a small particle size. The use of some of these parameters have a synergistic effect and can be coupled to finally obtain a mean crystal size of about 0.5 mm within a very reasonable time frame of 5-6 hours which we believe can be easily tailored for commercial synthesis of zeolite A. Another method to get small zeolite crystals has been the addition of nano-particles of various materials to act as substrates for zeolite A nucleation and growth. Synthesis using Titania Hombikat and Titania Hombifine has given promising results in this regard and zeolite A crystals nucleated on the surface on these substrates in the size range of about 0.3 mm were obtained. No zeolite A crystals were obtained in the case of other nano particles like Titania Ishihara, Titania Kemira, Iron Oxide etc. Contact angles between substrates, zeolite A and the synthesis medium along with the size of the substrate were found to be the important parameters influencing nucleation and growth rates of zeolite A crystals over the substrates. Growth rates of zeolite A over substrates was found to be significantly lower as compared to when there was no substrate even though the energy barrier for nucleation was found to be significantly lower in the former case. This could be attributed to the steric factors and was mathematically indeed proved to be so. Zeta potential measurements have been used to characterize the nano-particle materials used at pH conditions that match closely with that used in actual synthesis. X-Ray Diffraction (XRD), Laser scattering particle size analyzer, Scanning Electron Microscopy (SEM), EDAX, and Energy dispersive XRF have been used to characterize the zeolites synthesized.
Panagiotis Smimiotis (Advisor)
107 p.
sub-micron; heterogeneous; homogeneours; nucleation; growth

Recommended Citations

Citations

  • Brar, T. (2000). NOVEL WAYS OF SYNTHESIZING ZEOLITE A [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin973702236

    APA Style (7th edition)

  • Brar, Tenjinder. NOVEL WAYS OF SYNTHESIZING ZEOLITE A. 2000. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin973702236.

    MLA Style (8th edition)

  • Brar, Tenjinder. "NOVEL WAYS OF SYNTHESIZING ZEOLITE A." Master's thesis, University of Cincinnati, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin973702236

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Cincinnati and OhioLINK.
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