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Middle Distillate Fuels From Ethanol

ChemCatBio 2022 Technology Brief

This ChemCatBio study bridges biomass and carbon dioxide (CO2) utilization for the production of middle distillate fuels and longer-chain products with ethanol as a critical intermediate.

This study demonstrates a cost-competitive approach to make middle distillate fuels from renewable ethanol via innovations in catalysis. A market-responsive biorefinery was conceptualized around this C2 platform, where gasoline, jet, diesel, and chemical coproducts can be produced simultaneously. Researchers employed an integrated approach of combining experiments, techno-economic analysis, and life-cycle analysis.

Key Findings

Challenges and Next Steps

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Key Findings

Lewis Acid Zeolite Catalysts Enable Enhanced C3+ Selectivity

When catalyzed by Lewis acid zeolites, the pathway for forming carbon-carbon bonds exhibits much higher C3+ olefin selectivity compared to other direct ethanol-to-butene-rich olefin approaches. This is possible because such catalysts minimize ethanol dehydration to ethelyne through a unique active site combination. These catalysts also avoid significant carbon-carbon cleavage and over-hydrogenation of olefins, thereby preventing the formation of CO2 and light paraffins, respectively.

[CHART]
Ethanol conversion and C3+ olefin selectivity over different pathways and catalyst types.

C3+ Olefins Can Be Upgraded to Longer-Chain Hydrocarbons Over Several Solid Acid Catalysts

C3+ olefins obtained from this one-step ethanol conversion process are further oligomerized to longer-chain hydrocarbons over several solid acid catalysts, including Amberlyst-15, Amberlyst-36, and CT275. Findings suggest that gasoline, jet, and diesel cuts can be adjusted by using different oligomerization catalysts.

[CHART]
Liquid hydrocarbon distributions following oligomerization using Amberlyst-36, Amberlyst-15, and CT275.

The Approach for Making Middle Distillate Fuels From Renewable Ethanol Could Have Cost Advantages

Compared to two-step ethanol to butene-rich olefin processes, this one-step approach can reduce ethanol upgrading costs by as much as 42% ($0.60/gasoline gallon equivalent (GGE) vs $1.04/GGE). When using a pure ethanol feed, the baseline ethanol upgrading cost is $0.60/GGE, with capital expenses contributing 27% and operations 73% of the total cost.

[CHART]
Ethanol upgrading cost distributions for three cases with different ethanol concentrations.
[CHART]
Well-to-wake (WTWa) GHG emissions (gCO2e/MJ) of nine ethanol to jet (EtOH) cases compared with petroleum jet. GGE equals gasoline gallon equivalent.