Hydrogenation of fatty acid methyl esters to fatty alcohols at supercritical conditions

Abstract

Extremely rapid hydrogenation of fatty acid methyl esters (FAME) to fatty alcohols (FOH) occurs when the reaction is conducted in a substantially homogeneous supercritical phase, using propane as a solvent, over a solid catalyst. At these conditions, the limitations of hydrogen transport are eliminated. At temperatures above 240°C, complete conversion of the starting material was reached at residence times of 2 to 3 s, which is several orders of magnitude shorter than reported in the literature. Furthermore, formation of by-products, i.e., hydrocarbons, could be prevented by choosing the right process settings. Hydrogen concentration turned out to be the key parameter for achieving the above two goals. As a result of the supercritical conditions, we could control the hydrogen concentration at the catalyst surface independently of the other process parameters. When methylated rapeseed oil was used as a substrate, the hydrogenation catalyst was deactivated rapidly. However, by using methylated sunflower oil, a catalyst life similar to that obtained in industrial processes was achieved. Our results showed that the hydrogenation of FAME to FOH at supercritical conditions is a much more efficient method than any other published process.

Highly efficient Cu–Zn–Al catalyst for the hydrogenation of dimethyl adipate to 1,6-hexanediol: influence of calcination temperature

“…Typical conditions are: hydrogen pressures between 25 and 35 MPa, temperatures ranging from 250 to 350°C [8,9]. When applied in fixed-bed reactors, the throughput under such conditions is only about 0.2-0.3 m product 3 /m reactor 3 h -1 , high H 2 /substrate ratios are usually indispensable [10]. However, the use of toxic Cr and severe reaction conditions are problematic from environmental and energetic viewpoints.…”

Selective hydrogenation of fatty acids and methyl esters of fatty acids to obtain fatty alcohols–a review

“…The use of supercritical operation conditions were studied by Van den Hark et al They found that an extremely rapid hydrogenation of fatty acid methyl esters to fatty alcohols occurs when the reaction is conducted in a substantially homogeneous supercritical phase, using propane as a solvent, over a solid catalyst (chromium‐free, copper‐based catalyst, Davy Process Technology, Cleveland, England). In these conditions, the limitations of hydrogen transport are eliminated .…”

Electrochemical reduction of benzoic acid esters using water as a H/D source

“…For example, millions of tons of fatty alcohols are produced annually by reducing the corresponding fatty acid esters. 1 The most commonly used reductants for this purpose are hydrides such as lithium aluminum hydride (Scheme 1a). 2 However, because hydrides are usually water sensitive (and thus require special care during use) and produce at least stoichiometric by-products, the search for alternative, green methods for ester reduction has become an important research task in academia and industry.…”