Liquid-phase chloroform hydrodechlorination catalyzed by Pd/TiO2-Na

Chloroform (CLF) liquid-phase catalytic hydrodechlorination (HDC) using isopropanol as solvent and hydrogen source has been studied over Na-promoted and unpromoted titania-supported Pd catalysts, which were synthetized by wet-impregnation. The effect of the addition of NaOH on the catalytic activity and properties has been analyzed. The modification of the TiO2 with NaOH improves the catalytic activity of the final palladium catalyst. Thus, a high final conversion for chloroform was obtained over Pd/TiO2-Na (85.7%), in comparison to that over Pd/TiO2 (14.7%) or Pd/TiO2 + NaOH (37.0%). When NaOH was directly added to the reaction mixture, a negative effect was observed on the textural and metallic properties of the Pd/TiO2 catalyst, decreasing the specific area BET from 73 to 61 m(2)/g and Pd dispersion from 16.4 to 10.5%. On the contrary, the same physicochemical properties remained almost identical within experimental error, in the recycled Pd/TiO2-Na catalyst (around 68 m(2)/g and 24% for specific area BET and Pd dispersion, respectively), nonetheless, close to 40% of the sodium in the catalyst leaches during the reaction, but interestingly, the residual Na in the catalyst after its first use ("2.6 wt%) was stable and enough to attain significant CLF conversion ("79.8%), which suggest an acceptable stability for this material. (C) 2015 Published by Elsevier B.V.