Bio-oil Upgrading

Stabilization of bio-oils using low temperature, low pressure hydrogenation

Marjorie R. Rover, Patrick H. Hall, Patrick A. Johnston, Ryan G. Smith, and Robert C. Brown

The superficial similarities between petroleum and bio-oil have encouraged efforts to employ petroleum hydroprocessing in the upgrading of bio-oil. Any facile comparison is overshadowed by the fact that petroleum consists of non-polar hydrocarbons that are relatively stable, requiring elevated temperatures and pressures to encourage chemical transformations, whereas bio-oil consists of oxygenated organic compounds whose high degree of functionality makes them chemically reactive even at low temperatures and pressures.

[PHOTO]LTLP visualVisual appearance of cornstover-derived phenolics (stage fraction 1) dissolved in DMSO before hydrogenation and after 8 and 16 h of low-temperature, low-pressure (LTLP) hydrogenation.

Lignin-derived phenolic compounds readily polymerize and dehydrate to coke when hydroprocessed, resulting in low carbon yields of fuel range molecules and catalyst deactivation. In light of the limitations of conventional hydroprocessing, we explore low-temperature, low-pressure (LTLP) hydrogenation of pyrolysis-derived phenolics over 10% palladium on activated carbon (Pd/C) at 21°C and 1 bar pressure as a way to produce stabilized bio-oil at high yields.

[CHART]Changes in concentration, figure 4

Changes in concentrations of various functionalities after low-temperature, low-pressure hydrogenation of phenolic fractions 1 and 2 obtained from corn stover (CS) and red oak (RO).

 



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