Hydrodeoxygenation
{{Short description|Chemical process for removing oxygen from a compound}}
Hydrodeoxygenation (HDO) is a hydrogenolysis process for removing oxygen from oxygen-containing compounds. Typical HDO catalysts commonly are sulfided nickel-molybdenum or cobalt-molybdenum on gamma alumina. An idealized reaction is:Henrik Topsøe, Bjerne S. Clausen, Franklin E. Massoth "Hydrotreating Catalysis" Springer, 1996. {{ISBN|3540603808}}.
:
The first review on HDO was published in 1983.{{Cite journal|title = Catalytic hydrodeoxygenation|journal = Applied Catalysis A: General|date = 2000-06-12|pages = 147–190|volume = 199|issue = 2|doi = 10.1016/S0926-860X(99)00555-4|first = Edward|last = Furimsky| bibcode=2000AppCA.199..147F }} HDO is of interest in producing biofuels, which are derived from oxygen-rich precursors like sugars or lipids. An example of a biomass refining process employing hydrodeoxygenation is the NEXBTL process.
HDO of biomass fast pyrolysis vapors under low hydrogen pressures have recently attracted a lot of attention. Bulk molybdenum trioxide (MoO3) was used as catalyst and found to completely deoxygenate cellulose, corn stover, and lignin pyrolysis vapors and produce a stream of hydrocarbons including aromatics, alkenes, and alkanes.{{Cite journal|last1=Shanks|first1=Brent H.|last2=Zhang|first2=Jing|last3=Nolte|first3=Michael W.|date=2015-12-21|title=Ex situ hydrodeoxygenation in biomass pyrolysis using molybdenum oxide and low pressure hydrogen|journal=Green Chemistry|language=en|volume=18|issue=1|pages=134–138|doi=10.1039/C5GC01614B|issn=1463-9270}}{{Cite journal|last1=Shanks|first1=Brent H.|last2=Saraeian|first2=Alireza|last3=Nolte|first3=Michael W.|date=2017-07-31|title=Hydrodeoxygenation of cellulose pyrolysis model compounds using molybdenum oxide and low pressure hydrogen|journal=Green Chemistry|language=en|volume=19|issue=15|pages=3654–3664|doi=10.1039/C7GC01477E|issn=1463-9270}} From an economic viewpoint, only aromatics and alkenes should ideally be produced to enable product incorporation into the existing infrastructure.