Xiao Zhang

Graduation Semester and Year

2016

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Mechanical Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Brian Dennis

Abstract

Over the decades, seeking for an alternative energy source has been more and more significant because of increasing demand with rapid industry expansion. Liquid hydrocarbon from Fischer-Tropsch process is considered as an alternative fuel source because the product is considered as subtle for petroleum-derived. Syngas as feedstock for F-T process plays a crucial role in liquid hydrocarbon production. Among several commercial and experiment technologies, the most common technology for syngas production is natural gas reforming. The product from reforming process has proper carbon monoxide/hydrogen ratio for direct application in F-T synthesis. Meanwhile, combined carbon dioxide into reforming reaction has attracted more and more attention in recent studies, which has great potential to help reduce emission of greenhouse gas. However, the main challenge for reforming process is to maintain reaction for a long period running. In this study, a lab-scale reactor is designed and evaluated to achieve high efficiency for 2 types of reforming reaction, steam reforming and dry reforming.For this reactor, methane, the main content of natural gas, was used as reactant gas in the reactor for progressive understanding of reforming. The Nickel based catalyst supported by SiO₂ is preloaded and fixed in the catalyst zone of reactor. The selection and preparation for catalyst and support has been discussed in this study. For Steam Methane Reforming reaction, experimental work is conducted under Steam/Carbon ratio from 1 to 4, temperature range from 700 ̊C to 800 ̊C. Methane is fed to the reactor at flow rate 55 sccm at 1 atm pressure, where experimental conversion data were obtained. The conversion rate of methane is calculated as a standard for evaluation of reactor efficiency. As part of Fischer-Tropsch process, the quality of gas production is evaluated by H₂/CO ratio. The catalyst is examined by XRD and EDAX spectrum for carbon formation test. For Dry Methane Reforming reaction, experiment is conducted under a temperature range from 500 ̊ C to 700 ̊ C with molar ratio of CH₄/CO₂ 1. The total flow rate for mixture gas is 65 sccm. The conversion rates for both methane and carbon dioxide are calculated. The product quality is examined by H₂/CO ratio. The catalyst stability test is conducted in a high carbon intensity with a CO₂/CH₄ ratio 4 at 700 ̊ C and total flow rate 65 sccm. The catalyst is separately characterized in 3 different phases by SEM and XRD technology to identify carbon deposition. The results from experiments state that the reactor is able to convert methane to syngas with high efficiency and high tolerance for carbon deposition at high temperature environment. COMSOL software is applied for reforming reaction process simulation, and the results from simulation support the statement from experiment.

Keywords

Methane reforming experiment, Syn-Gas, Steam reforming, Dry reforming, XRD analysis

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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