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Process for production of jet-range hydrocarbons from crude Jatropha oil using hydrogen produced in-situ from formic acid

A team at the Korea Institute of Energy Research has developed a catalytic process for the production of jet-range oxygen-free hydrocarbons from crude Jatropha oil, using hydrogen produced in-situ from formic acid.

In a fixed bed reaction using a mixture of crude Jatropha oil and formic acid, normal hydrocarbon in the range of C10–C18 (mostly C15 and C17) was the main product—about 97% in the liquid product—and the degree of deoxygenation was about 99.5%. A paper on their work is published in the journal Fuel.

Generally, bio-jet fuel is produced from non-edible oils via previously mentioned commercial processes, where oils are hydro- deoxygenated and hydro-isomerized/cracked with hydrotreating catalysts and then distillated in sequence. However, a great amount of hydrogen is required to remove the oxygen in the molecules of oils (300–420 m3 of H2/m3 of vegetable oil). For minimization of hydrogen consumption, decarboxylation reaction of oils has been studied to take oxygen out of the oil molecules as CO2 gas, instead of hydro-deoxygenation.

… Recently, the direct formic acid fuel cell has been developed for portable power applications, where formic acid is a promising alternative fuel because it can produce hydrogen at relatively low temperatures over Pd/C catalyst (HCOOH → CO2 + H2). Therefore, in the present study, formic acid was applied for catalytic deoxygenation reaction, as not only a co-reactant but also a hydrogen donor. We conducted the catalytic decarboxylation reaction of crude Jatropha oil (CJO) over Pd/C catalyst to produce oxy-free hydrocarbons, assisted with hydrogen in-situ produced from formic acid solution (30%).

—Hwang et al.

Hwang
Catalytic deoxygenation for the production of n-paraffin from triglyceride: (a) decarboxylation reaction from triglyceride and (b) decarboxylation reaction in assistance with hydrogen in-situ produced from a hydrogen donor (glycerol). Source: Hwang et al. Click to enlarge.

For the study, the team used CJO, a Pd/C catalyst, and a co-reactant: either distilled water or a 30% formic acid solution. Formic acid generates hydrogen via its reforming reaction on Pd/C catalyst even at room temperature.

When no co-reactant was added to the CJO reactant, oxy-free hydrocarbons accounted for around 79% (51% for paraffin, 5% for olefin, and 22% for aromatics) in the liquid-phase product. However, oxygen-containing molecules such as ketone and alcohol and unidentified compounds were found in the liquid product.

When distilled water was used as co-reactant, a little bit higher amount of hydrocarbons (around 88%) was produced than with no co-reactant, but olefin hydrocarbon was not detected in the liquid product. Even though some hydrogen was generated to assist the hydrogenation reaction, FFAs in the liquid product still remained.

When formic acid solution was used as a co-reactant, the liquid product was all paraffinic hydrocarbons (pentadecane and heptadecane) and the percentage of FFAs was near to zero.

As results of continuous reaction in the fixed bed reactor, significantly higher degree of deoxygenation with a high initial resistance to catalyst deactivation was observed on Pd/C catalyst in the presence of formic acid. This means that addition of formic acid solution as the hydrogen donor is favorable [to] the deoxygenation reaction and the initial deactivation of catalyst.

—Hwang et al.

Resources

  • Kyung-Ran Hwang, Il-Ho Choi, Hye-Young Choi, Jeong-Sik Han, Kyong-Hwan Lee, Jin-Suk Lee (2016) “Bio fuel production from crude Jatropha oil; addition effect of formic acid as an in-situ hydrogen source,” Fuel, Volume 174, Pages 107-113 doi: 10.1016/j.fuel.2016.01.080

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