Removal of heteroatoms and metals from crude oils by bioconversion processes

摘要

The objective of this Cooperative research and Development Agreement project between Oak Ridge National Laboratory (ORNL) and Baker Performance Chemicals (BPC), Chevron, Energy BioSystems, Exxon, UNOCAL and Texaco is to investigate the biological desulfurization of crude oil. Biological removal of organic sulfur from crude oil offers an attractive alternative to conventional thermochemical treatment due to the mild operating conditions afforded by the biocatalyst. In order for biodesulfurization to realize commercial success, reactors must be designed which allow for sufficient liquid/liquid and gas/liquid mass transfer while simultaneously reducing operating costs. To this end we have been developing advanced bioreactors for biodesulfurization and have been studying their performance using both actual crude oil as well as more easily characterized model systems. This CRADA was originally established to be a 3 year program, but was extended to 5 years due to continuing interest. Because of business restructuring, UNOCAL, whose activities focused upon the supply and analysis of crude oil samples, was unable to continue its participation in the CRADA. Hence this report is designed to cover only LTNOCAL`s contribution to the CRADA as other aspects of the research are not yet complete. Experiments investigating the biological oxidative desulfurization of crude oil demonstrated that while dibenzothiophene like structures were readily degraded (>90% in 48 h) this desulfurization had minimal impact upon the total sulfur in the crude oil. This is because these structures represent less than 1% of the total sulfur found in the crude. Additional research is needed investigating sulfur speciation in crude oil with increased efforts upon broadening the sulfur specificity of the biocatalyst.