Abstract
A series of multicyclic hydrocarbons were synthesized in high yield and under mild conditions from 2,5-hexanedione, cyclohexanone and cyclopentanone, on a scale of 200 g. Aldol products were obtained with conversions of 95% (2,5-hexanedione), 80-90% (cyclopentanone) and 75-80% (cyclohexanone), based on the consumption of starting materials. Cyclopentanone and cyclohexanone aldol condensations resulted in mixtures containing mainly bicyclic products (90%) as well as tricyclic analogs (<10%). The 2,5-hexanedione aldol condensation produced 50% methylcyclopentenone (MCP) as expected and about 50% oligomers. Surprisingly, the complex heavy fraction after the removal of MCP contained mainly the products of Michael addition of MCP and only a minor fraction of the self-aldol condensation product of MCP. The hydrogenation-hydrodeoxygenation (HDO) of cyclohexanone- and cyclopentanone-derived reactants with a nickel on alumina (Ni-Al2O3) catalyst at 250 °C and pressures between 800 and 1200 psig produced the expected saturated hydrocarbons with good recovery (80% and 76% respectively), with only small amounts of oxygenated residual starting materials remaining (<2%). However, the HDO of the 2,5-hexanedione aldol mixture produced an equally complex mixture compared to its respective aldol/Michael addition product which contained unreacted oxygenates. All crude mixtures, only treated to remove water after HDO unless stated otherwise, were evaluated for their properties as potential compression-ignition fuels: distillation curve, derived cetane number, sooting tendency, lower heating value, density, flash point and cold flow properties. The results show the utility of these hydrocarbons as viable compression-ignition fuels or blendstocks, particularly the cyclopentanone- or cyclohexanone-derived products.
Original language | English |
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Pages (from-to) | 3143-3159 |
Number of pages | 17 |
Journal | Sustainable Energy and Fuels |
Volume | 5 |
Issue number | 12 |
DOIs | |
State | Published - Jun 21 2021 |
Externally published | Yes |
Funding
The research was supported by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy (EERE), and Bioenergy Technologies Office (BETO). The views expressed in the article do not necessarily represent the views of the U.S. Department of Energy or the United States Government. The authors gratefully acknowledge the support and guidance of Alicia Lindauer, Kevin Stork, DOE, and Dr Daniel Gaspar, PNNL. The authors are also grateful to Dr Michael Lilga (PNNL alumni) for formulating the early concept of HD oligomerization; Dr Henok Yemam (former PNNL) for conducting early Parr reactions with HD starting material; Dr Jonathan Male and Dr Evgueni Polikarpov (both of PNNL) for providing valuable review feedback for the manuscript; Cortland Johnson (PNNL) for improving the TOC image.
Funders | Funder number |
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U.S. Department of Energy | |
Office of Energy Efficiency and Renewable Energy | |
Pacific Northwest National Laboratory | |
Bioenergy Technologies Office |