The US Department of Energy (DOE) has issued a funding opportunity announcement (FOA) (DE-FOA-0000342) for up to $11 million over three years, seeking applications to develop integrated upgrading processes of bio-oils (biomass fast pyrolysis oils) at the bench scale. The proposed upgrading process must demonstrate the ability to produce a final liquid hydrocarbon transportation fuel that can be blended at up to 30% by weight with ASTM petroleum fuels or produce an upgraded bio-oil compatible with existing petroleum refining unit operations.
A recent FOA conducted by the Office of Biomass Programs directed the development of technology for the stabilization of bio-oils. (Earlier post.) This stabilization effort was focused on reducing solids content and the initial oxygen content of raw bio-oil while also selectively targeting carbonyl and carboxylic oxygen moieties amongst the molecular fragments making up bio-oil.
|Pyrolysis is the thermal decomposition of large molecules by heating in the absence of oxygen at more than 500 °C. One of the products of this process is pyrolysis oil.|
|Under appropriate pyrolysis operating conditions, biomass can be converted to relatively high yields (~70 wt %) of liquids—a mixture of organic compounds (pyrolysis oil) and water. The liquid organics are oxygenated hydrocarbon compounds resulting from the thermal breakdown of lignin, cellulose, and hemicellulose.|
|Collectively, pyrolysis oil comprises a complex mixture of acids, alcohols, aldehydes, esters, ketones, sugars, phenols, furans, and multifunctional compounds such as hydroxyacetaldehyde. The relative amounts of each compound class can vary depending on the biomass feedstock used and the operating conditions employed during pyrolysis.|
This prior R&D was intended to develop practical, cost-effective methods for stabilizing bio-oil for a minimum of six months of storage under ambient conditions. It was further intended to improve the chemical properties of bio-oil such that the bio-oil could be integrated into existing petroleum refinery operations.
However, the stabilized bio-oil is not considered to be suitable for drop-in use in a petroleum refinery primarily due to corrosive properties of the stabilized bio-oil.
This new FOA is requesting applications to develop integrated upgrading processes at the bench scale that will be capable of long term processing to address the corrosivity issues associated with stabilized bio-oil. It is expected that the upgrading technologies will involve the catalytic de-oxygenation of the many molecular fragments that collectively comprise bio-oil.
The upgrading/de-oxygenation of bio-oil can be incorporated into the pyrolysis process itself or as a subsequent upgrading step to raw or stabilized bio-oils. For the purpose of this FOA, stabilized bio-oil is assumed to have total acid numbers of <10 and char fines content of <0.5 wt%. Before stabilization, crude bio-oil should be consistent with the properties of Chemical Abstracts Registry Number 1207435-39-9 that has high initial oxygen levels, total acid numbers of 100-200, and typical solids content of 1-2 wt%.
DOE anticipates that the process will be catalytic based and the selected catalyst(s) will be able to direct the chemistry of oxygen rejection. The oxygen rejection is expected to take the form of CO2 or H2O as co-products of the upgrading reactions. This will be an important aspect of the process development because the nature of the oxygen rejection will impact both the final product yields and operating costs of the upgrading process.
Because of the importance of long term catalyst lifetime and performance in any catalytic process, this is an issue of particular importance to the objectives of this FOA. Additionally, the appropriate materials of construction for the process must be a consideration for commercial viability for both longevity and capital costs.
Applicants must also submit an analysis of greenhouse gas (GHG) reductions when compared to petroleum fuels.