Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemical and Biochemical Engineering

Supervisor

Dr. Hugo de Lasa

Abstract

This study reports a new fluidizable La2O3 promoted Ni/γ-Al2O3 catalyst. Prepared catalysts are characterized using BET specific surface area, XRD, TPR, TPO, H2-pulse chemisorptions, Pyridine FTIR, NH3-TPD and CO2-TPD. Catalytic steam gasification of biomass surrogates (glucose and 2-methoxy-4-methylphenol) are conducted in a CREC Riser Simulator under the expected conditions of a twin circulating fludized bed gasifier.

Catalyst structure-property and structure-reactivity relationships are established using characterization and gasification results. Gasification performance of a catalyst is found to be well-correlated as a function of its Ni dispersion and basicity/acidity ratio. It is hypothesized that acid sites of γ-Al2O3 are responsible for coke deposition via hydrocarbon cracking, whereas basic sites facilitated coke reforming. The relative proportion of octahedral and tetrahedral sites in γ-Al2O3, which is a main determinant of metal-support interaction and acid-base properties, is assessed using H2 TPR and NH3-TPD.

A 20% Ni/5% La2O3-γAl2O3 catalyst is developed, in this study, optimizing catalyst formulation and preparation conditions. This catalyst yields a 98.3% carbon conversion of glucose to permanent gases with no tar formation and negligible coke deposition. In the case of 2-methoxy-4-methylphenol gasification, a 89.8% carbon conversion with tar formation reduced to only 5.7% is achieved using this catalyst. The developed catalyst yields a high quality synthesis gas (H2/CO > 2) performing very close of the equilibrium. A mechanistic based kinetic model with statistically significant intrinsic kinetic parameters is also developed and validated using an independent set of experimental results.


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