Effect of surface Ti3+ on the sol–gel derived TiO2 in the selective acetylene hydrogenation on Pd/TiO2 catalysts

• Calcination under N2 atmosphere led to more surface Ti3+ defective sites on TiO2.
• The presence of surface Ti3+ increased Pd dispersion and hydrogenation activity.
• Electroless deposition (ED) provided higher Pd dispersion than impregnation.
• The catalyst performances were improved on Pd/TiO2–N2 prepared by ED.

The effects of calcination atmospheres (O2 and N2) and the preparation methods (impregnation and electroless deposition) on the physiochemical and catalytic properties of Pd/TiO2 catalysts were investigated in the selective hydrogenation of acetylene. The TiO2 supports calcined under O2 or N2 had similar crystalline phase, average crystallite size, and BET surface area, however, the amount of surface Ti3+ was significantly higher on the TiO2 calcined under N2. The dispersion of Pd metal and the metal–support interaction were influenced by the presence of Ti3+ on the TiO2 surface, resulting in modification of their catalytic performances in the selective hydrogenation of acetylene. In the present study, high ethylene selectivity (∼92%) can be obtained at complete acetylene conversion (100%) over the 1% Pd/TiO2–N2 prepared by electroless deposition method.

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