Production of drop-in biodiesel blendstocks <i>via</i> competitive acid-catalyzed dehydration reactions using ethanol oligomerization products

Canales, Emmanuel; Hower, Samuel C.; Li, Daniel Paul; Tambe, Aditya; Rothamer, David; Huber, George W.

doi:10.1039/d4se00362d

Cited by 3 publications

(2 citation statements)

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“…Phung et al studied the conversion of ethyl acetate over HY zeolites and observed that the acetic acid formed undergoes decomposition reactions on the catalyst to produce methane, CO 2 , and coke precursors, leading to a decrease in ethyl acetate conversion with time on stream. In previous work on dehydration of alcohols, our group also observed increased coke formation in the presence of esters compared to control experiments without esters. , Therefore, approaches to minimize the ester content of the reactant mixture prior to dehydration are needed to prevent a loss of catalyst activity.…”

Section: Introductionmentioning

confidence: 80%

“…We have previously studied ethanol conversion over a Cu catalyst supported on Mg–Al mixed oxides to produce a blend of alcohols, aldehydes, esters, ketones, ethers, and olefins. , We have then studied the dehydration of this mixture with an HY zeolite as shown in Scheme as reactions R1 and R2, where R1 produces diesel-range ethers . The mixture to be dehydrated contains esters that can hydrolyze over acid catalysts to produce carboxylic acids and alcohols (R3) or directly convert into carboxylic acids and alkenes (R4). , Carboxylic acids are known to adsorb strongly on the catalyst surface, causing catalyst deactivation .…”

Section: Introductionmentioning

confidence: 99%

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Catalytic Reduction of Esters over Zirconia-Supported Metal Catalysts

Chavarrio,

Kirkendall-Jones,

Dastidar

et al. 2024

ACS Catal.

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Esters are often produced as unwanted byproducts during the catalytic upgrading of ethanol to diesel fuel precursors through Guerbet coupling. Removal of esters from the product stream is important to prevent the loss of downstream catalyst activity from esterderived carboxylic acids. In this work, we studied ester hydrogenolysis to the parent alcohols as a viable route for enhanced diesel fuel production. Specifically, we investigated the reduction of hexyl acetate in butanol over ZrO 2 -supported Ni, Co, Cu, Rh, Pd, and Pt catalysts, where Cu/ ZrO 2 was the most selective catalyst for the hydrogenolysis of hexyl acetate into hexanol and ethanol. Thermodynamic analysis reveals that a 90% alcohol yield can be obtained at 200 °C, 30 bar, and a relatively high H 2 :hexyl acetate molar ratio of 480:1. Experimentally, an alcohol yield of 88% yield was obtained with a 10 wt % Cu/ZrO 2 catalyst at these conditions with a residence time of 5.4 h kg cat kmol gas −1 . Catalytic tests on the support revealed that ZrO 2 catalyzes the transesterification reaction between hexyl acetate and butanol. However, only the Cu sites can catalyze the hydrogenolysis of the esters into the final alcohols. We developed a kinetic model for our experimental results, which shows that the transesterification and hydrogenolysis reactions run at two different timescales, the former being 10 times faster than the latter. Data regression has been used to develop a model to predict the mole fraction distribution of ester hydrogenolysis products over a wide range of contact times. Cu/ZrO 2 loses half its catalytic activity after 80 h of time on stream. Modeling of deactivation data reveals that the ZrO 2 support conserves a residual activity due to external active sites, while active sites over the Cu surface deactivate at different rates. The catalytic conversion of esters into their parent alcohols is relevant to the production of surrogate liquid fuels since alcohols can be bimolecularly dehydrated to produce a blend of ethers with diesel fuellike properties.

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Section: Introductionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Catalytic Reduction of Esters over Zirconia-Supported Metal Catalysts

Chavarrio,

Kirkendall-Jones,

Dastidar

et al. 2024

ACS Catal.

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Scale-Up Studies for the Dehydration of C₄₊ Alcohols into Drop-In Diesel Fuel

Canales,

Witkowski,

Rothamer

et al. 2024

Energy Fuels

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Herein, we demonstrate the production of liter quantities of dropin diesel-range ethers from biomass-derived alcohols. We report scale-up results for the dehydration of a mixture of C 4+ alcohols using powder and pellet zeolite Y catalyst in continuous flow and batch reactors. The activity of zeolite Y decreases with the introduction of an alumina binder. Large alcohols, as well as branched and secondary alcohols, increase the coke content over the pellet Y catalyst. The pellet formulation had lower carbon balances and selectivity to C 10+ ethers, suggesting that the pellet formulation increases alcohol absorption and coke production. Crushing the pellet Y catalyst to smaller particle sizes does not recover the activity of zeolite Y in its powder form. Cold flow experiments show that particle agglomeration contributes to pressure buildup in the continuous flow reactor. C 10+ ether blends can be produced in batch reactors at high alcohol conversion regimes. One liter of a diesel #2 blend was produced by scaling up this reaction. The final blend consists of a substantial portion of C 10+ ethers (63.7 wt %), followed by heavy unknown products (27.4 wt %). The final alcohol and butyl ether concentration values were 7.3 and 1.5 wt %, respectively. The blendstock reported in this paper can satisfy diesel #2 ASTM standards for density, cloud point, flashpoint, and cetane number.

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Advanced diesel from ethanol: a pathway to produce sustainable and high-quality drop-in biofuels

Restrepo-Flórez,

Chavarrio,

Canales

et al. 2025

Sustainable Energy Fuels

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Production of drop-in biodiesel blendstocks via competitive acid-catalyzed dehydration reactions using ethanol oligomerization products

Abstract: Ethanol can be converted into diesel fuel ethers using a three-step catalytic approach that involves ethanol oligomerization to larger alcohols, hydrogenolysis of the esters followed by dehydration of the C4...

Cited by 3 publications

References 34 publications

Catalytic Reduction of Esters over Zirconia-Supported Metal Catalysts

Catalytic Reduction of Esters over Zirconia-Supported Metal Catalysts

Scale-Up Studies for the Dehydration of C₄₊ Alcohols into Drop-In Diesel Fuel

Advanced diesel from ethanol: a pathway to produce sustainable and high-quality drop-in biofuels

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Production of drop-in biodiesel blendstocks via competitive acid-catalyzed dehydration reactions using ethanol oligomerization products

Abstract: Ethanol can be converted into diesel fuel ethers using a three-step catalytic approach that involves ethanol oligomerization to larger alcohols, hydrogenolysis of the esters followed by dehydration of the C4...

Cited by 3 publications

References 34 publications

Catalytic Reduction of Esters over Zirconia-Supported Metal Catalysts

Catalytic Reduction of Esters over Zirconia-Supported Metal Catalysts

Scale-Up Studies for the Dehydration of C4+ Alcohols into Drop-In Diesel Fuel

Advanced diesel from ethanol: a pathway to produce sustainable and high-quality drop-in biofuels

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Scale-Up Studies for the Dehydration of C₄₊ Alcohols into Drop-In Diesel Fuel