Effects of DTAB on Performance of Nano Pd/C Catalyst for Purification of Terephthalic Acid

The 0.5 wt.% Pd/C catalysts used for purification of terephthalic acid(TA) were prepared, and the effects of dodecyltrimethylammonium bromide(DTAB) concentration on activity and microstructure of catalysts were investigated by means of SEM, TEM, XRD,HPLC,specific surface area(BET) and porosity test. The results show that DTAB can increase the activity of Pd/C catalysts, and the catalytic activity increases with the increase in DTAB concentration and nearly remains constant with further increase after it exceeds 0.5 wt.%.. DTAB can clean the surface of activated carbon and diminish the palladium size of Pd/C catalysts. The addition of DTAB has effects in crystal structure of nano Pd/C catalysts, and the Pd crystal planes of (111) and (200) was replaced by a broad reflections after DTAB added. DTAB tends to form various meta-stable structures(spherical or cylindrical)at the solid-liquid interface that helps finer grain for mation and hinders subsequent coarsening of the palladium particles.