Date of Award
Master of Science (MS)
This study builds upon previous research at UND which demonstrated that crop oils are a potential renewable alternative to select petroleum based products. The crop oils investigated for this study include soybean, canola, and jojoba oil. The processing method utilized was a non-catalytic cracking process.
The goal of this work was to build a new bench-scale continuous flow thermal cracking reactor system capable of being operated under high pressure, and also to use this reactor to explore the effects of pressure, temperature, and feed rate during non-catalytic cracking on the yield and composition of the liquid and gas products produced from the three crop oil feedstocks studied.
The reactor developed for this work was a 9.7 L bench scale, continuous stirred tank unit. The continuous flow and scale of this design is significant, as published research into the thermal cracking of crop oils has focused on utilization of batch reactors and lab scale continuous flow reactors.
A split-plot full factorial experimental design was used to study the effects of pressure, temperature and feed rate on soybean oil feedstock. For these experiments, pressures ranged from 1.38 to 2.76 MPa gauge (200 to 400 psig), temperatures ranged from 400 to 420Â°C, and feed rates were 4.0 to 7.0 L/hr (0.41 to 0.72 liquid hourly space velocity (LHSV)). In addition, a side by side comparison among soybean, canola, and jojoba oil feedstocks at thermal cracking conditions of 1.38 MPa gauge (200 psig), 420Â°C, and 4.0 L/hr were conducted.
Design of Experiments (DOE) response measurements included with this work are liquid distillate yields, liquid product acid number, gas product constituent yields, and gas product constituent molar concentrations.
The DOE significant findings showed that soybean oil middle distillate (150 to 250Â°C) product yield was favored at lower pressure (1.38 MPa gauge (200 psig)), higher temperature (420Â°C), and lower feed rate (4L/hr), and that all three variables were significant factors per the DOE. Acid number testing did not correlate with the level of liquid product decarboxylation, and ethylene was the only gas product yield identified with pressure as a significant factor per the DOE. A non-DOE finding suggests that pressure can be used to favor alkane over alkene products
The side by side comparison of soybean, canola, and jojoba oil feedstock showed that the predominate C42 wax esters of jojoba oil proved much less responsive to thermal degradation than the predominant C18:2 polyunsaturated fatty acids of soybean oil and C18:1 mono unsaturated fatty acids of canola oil.
Sander, Blake, "A Study Of Bench Scale, Pressurized, Continuous Flow Thermal Cracking Of Crop Oil" (2014). Theses and Dissertations. 1591.