Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.720522
Title: Development of a continuous process for direct amide synthesis over titania based magnetic catalysts under RF heating
Author: Liu, Yawen
ISNI:       0000 0004 6349 030X
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2017
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Abstract:
In this work, TiO2 as the catalyst to catalyse the direct amide synthesis was firstly optimized by sulfation. The type and amount of sulfate sources were varied to modify the acid sites on the titania surface, resulting in different catalytic activities. Composite magnetic catalysts (CMCs) having magnetic and catalytic parts with three different structures have been synthesized. In the first method, a series of CMCs containing 33-50 wt.% of sulfated TiO2 onto NiFe2O4 were synthesized by ball milling. Mechanochemical synthesis was found to be a facile route to provide a strong contact between magnetic and catalytic nanoparticles. In the second method, TiO2/NiFe2O4 core-shell CMCs with a titania loading of 9-32 wt.% were synthesized by sol-gel method. The effects of calcination temperature and titania loading on their catalytic activity and stability were studied. The structure of TiO2/NiFe2O4 core-shell CMCs was further improved by synthesizing a middle layer of SiO2 between the core and TiO2 shell in the third method. The obtained CMCs were further sulfated by two methods to promote the activity. The CMCs were characterized by XRD, SEM, TEM, XPS, TGA, VSM, FT-IR of adsorbed pyridine, N2 adsorption/desorption isotherms and measurement of specific absorption rate. The catalytic activity was measured in the reaction between 4-phenylbutyric acid and aniline in the 140-200 oC range at a pressure of 6 bar in both batch and continuous modes. The reaction rate over the optimal sulfated TiO2 was four-fold of that over the initial TiO2. The effect of reaction temperature on deactivation was studied. For CMCs, the reaction rate over titania in an optimised NiFe2O4@SiO2@TiO2 CMC was 1.5 times higher than that over titania in ball milled CMC. The catalytic activity of this CMC could be totally recovered by a regeneration protocol in the RF-heated flow reactor at mild conditions. However, the catalyst deactivation kinetics was substantially reduced after each cycle. Finally, a near-isothermal RF-heated continuous reactor was designed to scale-up the amide synthesis to a larger production scale. The throughput of 4, N-diphenylbutyramide was 0.27 g/h, which was five-fold of that shown in the literature [1].
Supervisor: Not available Sponsor: University of Warwick ; European Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.720522  DOI: Not available
Keywords: QD Chemistry
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