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Developing Synthesis and Characterization Methods for Enhancing Material Performance

Parulkar, Aamena
http://orcid.org/0000-0001-6700-5461
http://rave.ohiolink.edu/etdc/view?acc_num=osu1542739064703435

Abstract Details

2018, Doctor of Philosophy, Ohio State University, Chemical Engineering.
Design and development of functional nano materials especially, heterogeneous catalysts can directly impact the sustainability of industrial processes. This dissertation focuses on developing novel synthetic strategies and utilizing advanced characterization techniques to synthesize functional nanomaterials with focus on designing well-defined catalysts. The primary focus is on synthesizing and catalytic testing of Lewis acidic nano-zeolites. Lewis acidic zeolites, especially, tin containing zeolites like Sn-Beta and Sn-MFI, have been shown to catalyze a large array of chemical reactions. However, micropores of these zeolites can reduce the catalytic performance because of diffusion limitations. To overcome these limitations, strategies including development of hierarchical structures and reduction in particle size have been investigated. Nonetheless, synthesizing Lewis acidic nano-zeolites still remains a challenge. In this work, the synthesis conditions are modified to achieve a five-fold reduction in particle size for Sn-MFI (nSnMFI) as compared to conventional synthesis (cSnMFI). To demonstrate the benefit of nano-zeolites for catalytic application, epoxide ring opening (ERO) with alcohol is used as a probe reaction. Enhanced diffusion within the nSnMFI improves catalytic performance for bulky reactants, while retaining the inherent activity of the catalytic sites. The advantage of nSnMFI is however limited by the small pore size of MFI structure. To expand the scope, nano-Sn-Beta, a large pore zeolite is also synthesized. The improvement in performance over nSnMFI and conventional Sn-Beta zeolite is demonstrated using ring opening of 1,2-epoxyoctane with ethanol. Designing and modifying the structure of catalytic sites can further tune the catalytic performance. Sn- Beta zeolite has two types of active sites; (1) closed Sn-site (Sn(OSi)4) and (2) open Sn-site (Sn(OH)(OSi)3), that can have different activities for certain reactions. Strategies are employed to design catalysts with a varying distribution of open and closed Sn sites. The effect of open versus closed Sn-site is studied for ERO, demonstrating that both the sites have similar activity for this reaction. Another aspect of nanomaterial development is designing strategies to synthesize nanoparticles with uniform particle size distribution (PSD). This is shown via synthesizing uniform nanoparticles of size 60-80 nm of zeolitic imidazolate framework (ZIF-8) using a novel jet-mixing (JM) reactor. The intense mixing provided by the JM reactor reduces the mixing time scale resulting in uniform reaction conditions in the reaction volume. This chemical uniformity results in improved utilization of precursors in addition to a narrow PSD of product. The effect of different synthesis parameters is studied and it is shown that JM reactor has potential for scalable synthesis of nanomaterials. Finally, ion-mobility mass spectrometry (IMMS) an advanced characterization technique is used to rapidly screen the performance of catalysts for hydrodenitrogenation (HDN) of vacuum gas oil (VGO). The insights obtained from IMMS analysis of VGO samples before and after treatment using different catalysts allowed identifying differences in the type of nitrogen species removed. Using the data, a layered bed catalyst design is tested that shows improved performance for given reactor volume. Overall, synthesis, characterization, and testing methodologies demonstrated in this dissertation demonstrate a diverse toolbox for designing and developing functional nanomaterials.
Nicholas Brunelli, Ph.D (Advisor)
Li-Chiang Lin, Ph.D (Committee Member)
Stuart Cooper, Ph.D (Committee Member)
212 p.
Chemical Engineering
Nano zeolites; Heterogeneous catalysis; Lewis acidic zeolites; epoxide ring opening with alcohols; Jet mixing reactor; Ion mobility mass spectrometry

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Citations

  • Parulkar, A. (2018). Developing Synthesis and Characterization Methods for Enhancing Material Performance [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1542739064703435

    APA Style (7th edition)

  • Parulkar, Aamena. Developing Synthesis and Characterization Methods for Enhancing Material Performance. 2018. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1542739064703435.

    MLA Style (8th edition)

  • Parulkar, Aamena. "Developing Synthesis and Characterization Methods for Enhancing Material Performance." Doctoral dissertation, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1542739064703435

    Chicago Manual of Style (17th edition)

osu1542739064703435
273
© 2018, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.