Date of Award

Spring 2021

Project Type

Dissertation

Program or Major

Chemical Engineering

Degree Name

Doctor of Philosophy

First Advisor

Nan Yi

Second Advisor

P T Vasudevan

Third Advisor

Xiaowei Teng

Abstract

Dry reforming of methane (DRM) offers benefit of consuming two important greenhouse gases(CH4 and CO2) in a single reaction to produce syngas. Ni-based catalysts have been studied for DRM. However, monometallic Ni catalysts deactivate mainly because of coking. We were motivated to include earth-abundant promoter metals to suppress coke formation and studied a series of bimetallic nickel-iron catalysts supported over TiO2 and TiO2-CeO2 at 550˚C and atmospheric pressure. This dissertation mainly focuses on various approaches to synthesize Ni-Fe catalysts and examines the effect of oxide support modification over optimum Ni-Fe/TiO2 catalyst. In this context, Ni-Fe catalysts supported over TiO2 were prepared by mainly two approaches – incipient wetness impregnation and co-precipitation methods. The total metal loading of Ni+Fe was maintained at 10 wt% while different ratios of Ni/Fe were investigated. We further explored the effect of oxide support modification by substituting 20 wt% TiO2 with CeO2 over a Ni-Fe/TiO2 catalyst showing high activity and simultaneous minimum coke formation. Bimetallic Ni-Fe catalysts were characterized by various techniques including Temperature Programmed Reactions (TPRs), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetry Analysis-Differential Thermogravimetry (TGA-DTG), Raman Spectroscopy and In-situ DRIFTS analysis. Conclusively, we found that addition of Fe is beneficial to inhibit coke deposition owing to its redox properties during low temperature DRM, while addition of CeO2 adds to coke inhibition property of Ni-Fe/TiO2 catalysts. However, Ni/Fe ratio of 3:1 is essential for better activity performance and simultaneous resistance to coke formation.

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