Exploration and Production Technologies

Developing Enzyme and Biomimetic Catalysts for Upgrading Heavy Crudes via Biological Hydrogenation and Hydrodesulfurization

FEW49022 

Program

This project was funded through DOE's Natural Gas and Oil Technology Partnership Program. The program establishes alliances that combine the resources and experience of the nation's petroleum industry with the capabilities of the national laboratories to expedite research, development, and demonstration of advanced technologies for improved natural gas and oil recovery.

Project Goal
The project goal was to develop a hydrogenation catalyst capable of operation at moderate or mild conditions.

Performers
Argonne National Laboratory (ANL)
Argonne, IL

Oak Ridge National Laboratory (ORNL)
Oak Ridge, TN

Project Results
Selected enzyme catalysts were subjected to kinetic testing and thermal stability tests. EXAFS technology allowed improvement of the catalysts for operation under moderate conditions. 

Benefits
In order to make biological enzymes work with compounds in crude oil, it is necessary to create favorable binding interactions between the oil substrates and enzymes. The difficulty in coupling enzymes with the hydrophobic substrates in oil can be overcome by reducing the polarity or increasing the hydrophobicity of the enzyme's substrate docking site. This modification was done at ORNL. The approach was based on understanding the enzyme-substrate interaction and then modifying the enzyme to improve its activity.

The improvements are to be partly assessed using EXAFS technology in collaboration with ANL. Selected enzyme catalysts were subjected to kinetic testing and thermal stability tests. Industrial input will be sought in catalyst development as well as in performing preliminary economic analysis.

Ultimately, the work is expected to benefit U.S. refiners by developing an environmentally friendly technology that provides a less-severe method of processing heavy crude oils than conventional upgrading techniques while helping to reduce corrosion in process units.

Background
The processing of heavy oils is currently plagued by two major problems: dealing with the presence of asphaltenes, which increases oil viscosity, and with the heteroatom content, which poses corrosion and complex-refining problems. Technology is needed to process heavy crudes in such a way as to reduce viscosity and heteroatom content under mild conditions. Additions of hydrogen to aromatic and heteroatom molecules via a biological route can be a potentially attractive alternative to upgrading heavy crudes. However, hydrogen addition to molecules existing in petroleum by using natural enzymes is difficult.

Project Summary
The laboratory set-up was updated to carry out anaerobic microbiology and enzymology work for the modification of hydrogenase enzymes to be developed into desulfurization biocatalysts. A collaboration was set up with Dr. Mike Adams at the University of Georgia, Athens, GA, to obtain the thermophilic hydrogenase enzyme and to study its activity against organosulfur compounds.

A Cooperative Research and Development Agreement was developed with Texaco (now part of Chevron) and ANL to facilitate further testing and to allow protection of the resulting proprietary property. 

At ANL, catalyst-testing units were modified for testing of catalyst samples received from ORNL. These units include a plug flow unit that can study supported enzymes and a stirred autoclave for studying unsupported enzymes. The plug flow unit also has a back-mixed reactor cell for studying long-term deactivation patterns for the most promising catalyst systems. In-situ EXAFS cells have been modified and tested for on-stream collectiong of data for promising catalyst leads. With this equipment, researchers hope to be able to tell the coordination sphere and oxidation state of the active metals in time slices as small as one minute under reaction conditions.

Current Status (October 2005)
The project is complete.

Project Start: April 11, 2001
Project End: April 11, 2004

Anticipated DOE Contribution: $259,000 
Performer Contribution: $151,000 (36 % of Total)

Contact Information
NETL - Kathleen Stirling (kathy.stirling@netl.doe.gov or 918-699-2008)
ANL - Richard Baker (richard.baker@anl.doe.gov or 708-252-2647) 

 
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