Hydrodechlorination of 4-chlorophenol in aqueous phase using Pd/AC catalysts prepared with modified active carbon supports

Catalysts based on large size-controlled Pd nanoparticles for aqueous-phase hydrodechlorination

“…Therefore, no formation of NPs took place in the bulk solution or those formed were adsorbed on the support. CB was used as support as received and also after oxidization (CBox) with HNO 3 , as described elsewhere [17].…”

“…Different effects due to support oxidation have been reported for HDC catalyst prepared by incipient wetness impregnation. Calvo et al [17] observed an increase of the activity of Pd/activated carbon catalysts in the HDC of 4-CP that was ascribed to surface oxygen groups, whereas Diaz et al [59] reported lower initial TOF values for Pd supported on oxidized graphites in the HDC of tetrachloroethylene. In the current work, the main cause of the lower activity of the CBox-supported catalysts must be the poor dispersion of Pd on that support during the in-situ synthesis, probably associated to the interaction of the support with the water/methanol mixture, as indicated before.…”

“…Calvo et al [17] reported that the presence of carboxylic acid and lactone surface groups in activated carbons were relevant to obtain Pd-based catalysts with both high conversion and selectivity to the less toxic product, in the HDC of 4-chlorophenol (4-CP). Burgess et al [50] found that Au NPs showed a better dispersion on a graphite surface containing hydroxyl groups than on a ketone-covered graphite surface.…”

“…The most relevant are those related to the active phase, i.e. nanoparticles (NPs) size [5][6][7][8] and shape [9][10][11][12], and to the support, mainly pore size [13][14][15][16] and surface chemistry [17][18][19][20], but also the way of catalysts synthesis can affect the activity and/or selectivity [21,22].…”

Effect of size and oxidation state of size-controlled rhodium nanoparticles on the aqueous-phase hydrodechlorination of 4-chlorophenol

“…This type of xenobiotic compounds are toxic and carcinogenic [3,4] and have no natural ways of remediation, so chlorophenols persist in the environment and can produce both adverse ecological effects and severe impacts on public health [5]. The main advantages of HDC compared to other techniques of potential application have been reported in the literature [6][7][8] and can be summarized in the ability to treat a wide range of concentrations, the operation at mild conditions and the low reagents demand. Moreover, HDC shows a high selectivity towards less toxic by-products that could be recoverable, when waste valorization is possible, or safely delivered to a further biological treatment.…”