Regulation of sulfur doping on carbon-supported Pd particles and abnormal relationship between Pd particle size and catalytic performance in selective hydrogenation of o-chloronitrobenzene

S was successfully doped into carbon via calcination and Pd size was modulated by adjusting the S content. Sulfur species were considered to be anchor sites, contributing to the highly dispersion of Pd nanoparticles. In addition, Pd/CS4 achieved 99.9% sel. With complete conversion in hydrogenation of o-chloronitrobenzene compared to Pd/AC (99.9% con., 61.6% sel.). Interestingly, catalysts with smaller metal size exhibited higher selectivity and lower activity, which was contrary to previous studies. It was suggested that electronic effects between S and Pd played an important role in this reaction, contributing to the excellent performance of the catalysts.