Semester

Spring

Date of Graduation

2022

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Chemical and Biomedical Engineering

Committee Chair

Jianli Hu

Committee Member

Debangsu Bhattacharyya

Committee Member

Jeremy Hardinger

Abstract

Accompanied by the development of modern industry, the demand for light olefins (e.g., ethylene, propylene, butene, butadiene) increases year by year. Light olefins are important intermediates in producing polymers (Polyethylene, Polypropylene, etc.) and rubber (Styrene Butadiene Rubber, Polybutadiene rubber, etc.). The primary process for the production of light olefins is steam cracking of petroleum liquids (naphtha and distillate fuel oil). It is an energy-intensive process, requiring high temperature (750-850℃) and pressure (1.0-4.5 MPa). Meanwhile, due to undesired side reactions, this process has lowered the efficiency of light olefins production and suffers from severe coking issues. Furthermore, as petroleum liquids become lighter, the steam cracking products are shifted to ethylene.

Besides petroleum liquids, ethane is a promising feedstock for ethylene production by steam cracking. Inexpensive ethane derived from natural gas is widely available. Using ethane as a feedstock is far superior in terms of cost to naphtha feedstock. However, steam cracking of ethane is an energy-intensive process too, due to the high reaction temperature (> 800℃). Moreover, the product is limited to ethylene, other light olefins are hard to produce by ethane cracking.

Catalytic ethane dehydrogenation (EDH or ODH) is an attractive alternative to ethane cracking because of relatively low reaction temperatures, and high flexibility for making other light olefins and valuable aromatics. However, rapid coking, catalysts deactivation, low conversion, and low selectivity are still the key challenges in catalytic ethane dehydrogenation. The major hurdle in developing a commercially viable EDH or ODH technology is catalyst deactivation and high energy consumption.

In this study, the ceria-supported Ru/CeO2 and Cs promoted ceria-supported CsRu/CeO2 catalysts were developed for EDH and ODH process and demonstrated higher activity and long-term stability. The effects of process parameters were investigated to optimize the light olefins production from ethane. Meanwhile, the microwave-enhanced EDH and ODH process was conducted at lower temperatures to reduce energy consumption and obtain higher diversity of light olefins. It proved that microwave-enhanced ethane catalytic conversion could reach the equivalent level of performance at temperature 150-200℃ lower than in the conventional thermally heated fixed-bed reactor. Under microwave ODH conditions, ethylene, propylene, butene, and butadiene are formed at a lower temperature (500℃-600℃), whereas they will need a higher temperature (750-800℃) under thermal fixed-bed conditions.

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