Liquid-phase hydrogenation of citral for production of citronellol: catalyst selection

The kinetics of citral hydrogenation over Pd supported on clinoptilolite rich natural zeolite

“…The selectivities established by others were 88% over Pd/SiO 2 -AlPO 4 [4], 70% over Pd/SiO 2 [11] and 87.5% over Pd/polymer and 67.5% for Pd/C [8]. The effect of zeolite support was reported by Maki-Arvela et al [9]. A low selectivity to citronellol and citronellal (36%) was obtained over zeolite supported Ni catalysts (Ni/H-Y and Ni/NH 4 -Y) [9].…”

“…The effect of zeolite support was reported by Maki-Arvela et al [9]. A low selectivity to citronellol and citronellal (36%) was obtained over zeolite supported Ni catalysts (Ni/H-Y and Ni/NH 4 -Y) [9]. However, with SiO 2 or Al 2 O 3 supports, Ni catalyst was found to be very selective to citronellol and citronellal (>70%).…”

“…In the present study, the use of Cl precursor was avoided. The impurities in the catalyst support [8], the acid sites in the catalyst [9] and the acidity of the ethanol were also associated with acetal formation [8,26]. Further investigation is needed to determine what caused the acetal formation.…”

“…Therefore, many studies have been pursued to develop a suitable industrial catalyst that would be able to lead to a very high selectivity at total conversion [4,[6][7][8][9][10][11]. However, the effect of reaction parameters on selectivity and the catalyst regeneration for a given catalyst are rarely studied.…”

“…The final selectivity of an active metal can be modified by using an adequate support [2,7,9,12], which interacts with the metal, or by adding a second component as a promoter [13][14][15]. Electronic effects and geometric effects have been suggested as the explanation for the improvement in selectivity to unsaturated alcohols.…”