Graduation Year

2017

Document Type

Thesis

Degree

M.S.C.H.

Degree Name

MS in Chemical Engineering (M.S.C.H.)

Degree Granting Department

Chemical Engineering

Major Professor

John N. Kuhn, Ph.D.

Co-Major Professor

George Philippidis, Ph.D.

Committee Member

Scott W. Campbell, Ph.D.

Keywords

Algae, Light Alkenes, Petrochemicals, Renewable Technology, Sustainability

Abstract

The global demand and sustainability concerns for producing light olefins encouraged researchers to look for an alternative and sustainable feedstock. Alkenes, such as ethene, propene and butene, are known as light olefins. Olefins are the backbone of the chemical industry because they serve as the chemical building blocks for the manufacture of polymers, fibers, and numerous organic chemicals. Feedstocks such as naphtha, natural gas and liquefied petroleum gas (LPG) are currently used for producing light olefins, but they are non-renewable and hence unsustainable. In contrast, biomass as a potential feedstock for the production of fuels and chemicals is renewable. Microalgae, in particular, are a promising resource due to their fast growth rate and ability to act as a CO2 sink.

The objective of my research was to assess the potential of thermochemical production of the light olefins ethene, propene, and butene from the marine microalga Nannochloris oculata in the absence and presence of catalysts and study the effect of catalyst to cell mass ratio on the production of these chemicals. Thermal cracking was conducted using two catalysts, aluminosilicate (Si/Al) and H-ß zeolite at 400-650 °C in a semi-batch reactor system and gas analysis was performed using mass spectrometry. Cracking of N. oculata by the aluminosilicate catalyst was studied in more detail at catalyst-to-algae mass ratios of zero, 5:1, 10:1 and 20:1 using (Si/Al) catalyst and a comparative study was performed at catalyst-to-algae mass ratio of 10:1 using (Si/Al) and H-ß zeolite catalyst. The formation of light olefins ethene, propene, and butene was quantified. Higher temperature and catalyst to algae ratio led to an increase in the yield of all olefins, although a diminishing effect was observed above 600 °C and a ratio of 5:1. Although ethene was the most significant product, the concentration of all olefins increased significantly, when catalysts were employed in the cracking reaction. Moreover, the comparative study revealed that ethene was the most significant product when (Si/Al) was used and propene was the most significant product when H-ß zeolite was used.

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