Access Type

Open Access Dissertation

Date of Award

January 2012

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Chemical Engineering and Materials Science

First Advisor

Simon K. Ng

Second Advisor

Steven O. Salley

Abstract

The focus of this research is to prepare non-sulfided hydrotreating catalysts, supported noble metal and transition metal carbide/ nitride, and evaluate their hydrocracking activities and selectivities by using soybean oil as the feedstock. For comparison study, catalytic cracking of soybean oil over a commercialized ZSM-5 was investigated. However, steady state could not be reached because significant amounts of tar and coke were generated during the reaction though a high yield (21%) of jet fuel was obtained from the process. Compared to the catalytic cracking process, less tar and coke were formed during the hydrocracking process and stable continuous flow reaction was obtained by using the bifunctional Ru/ZSM-5 catalyst. 16% yield of jet fuel, which is comparable to yields over commercialized sulfided NiMo catalysts while at a much lower pressure of 650 psi was produced. A 20 - 29% diesel yield was also obtained during the process. But coke was the issue with this noble metal catalyst.

In the following stage, novel bi-functional catalysts, NiMo carbide or nitride supported on ZSM-5, zeolite â, USY, ã-alumina oxide, and Al-SBA-15 were prepared by the temperature-programmed reaction method and the effects of process parameters on catalytic hydrocracking of soybean oil were investigated. 100% conversion of soybean oil was attained under the 650 psi and 360-450 oC reaction conditions. Among them, three zeolite supported carbide catalysts showed high selectivity to green gasoline (about 15-40%) due to the high cracking activities. ã-alumina and Al-SBA-15 supported catalysts mainly produced green diesel fuels. Especially Al-SBA-15 supported NiMo carbide catalyst gave the highest yield of organic liquid product (96%) and highest selectivity (97%) to hydrocarbons in the boiling range of the diesel fraction. The study of carbide and nitride catalysts provides a promising approach for preparing drop-in fuels from renewable resources under a lower pressure without sulfurization reagents involved in the process. NiMoC/Al-SBA-15 showed the greatest potential for producing green diesel from renewable feedstock.

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