Graduation Year

2019

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Chemical Engineering

Major Professor

Venkat Bhethanabotla, Ph.D.

Co-Major Professor

John Kuhn, Ph.D.

Committee Member

Scott Campbell, Ph.D.

Keywords

catalyst, pellet, perovskite oxide catalyst, SiO2 support

Abstract

In order to solve the increasing greenhouse effect problem, perovskite-type oxides have been used to convert CO2 to CO in a reverse water-gas shift chemical looping (RWGS-CL) process. Currently, the process is at the micro-reactor scale and used catalyst in powder form. However, formed materials are needed if the scale is to be increased.

Our research focus is on increasing the conversion yield of perovskite oxides with SiO2 support and scaling up the powder form perovskite-type oxides to pellet by extrusion. The binder added during the extrusion process must be removed to avoid affecting the performance of the catalyst and to provide porosity, without substantially lowering the mechanical strength. X-ray diffraction was utilized to identify the crystal structure and determine the crystal stability after the conversion. Temperature programmed reduction (TPR) and temperature programmed oxidation (TPO) experiments were performed to identify the conversion temperature and redox properties of the materials.

The extrusion method used in this research uses only organic binder and water to assisted extrusion process, remove binder in the calcination to maintain the activity and conversion properties of the catalyst, while the mechanical strength of the pellet meets industrial requirements. Compared to pure perovskite-type oxides, sample La0.75Sr0.25FeO3 mixed with SiO2 (mass ratio was 50:50) had better conversion performance and stronger mechanical strength after extrusion.

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