Selective oxidation of glycerol with oxygen in a base-free aqueous solution over MWNTs supported Pt catalysts

Abstract

Selective oxidation of glycerol with molecular oxygen was studied over different functionalized MWNTs supported Pt catalysts in base-free aqueous solution. N2 adsorption, IR, Raman and SEM–EDS analysis confirmed that the tubular structure of MWNTs is stable during HNO3 and H2O2 pretreatment and the surface of MWNTs was successfully functionalized by HNO3, H2O2 and NH2–CH2–CH2–SH. XRD, SEM and TEM analysis demonstrated that unique sized Pt particles formed on S-pretreated MWNTs. Pt/S-MWNTs catalyst with small Pt particles was more active than Pt/MWNTs, Pt/HNO3-MWNTs and Pt/H2O2-MWNTs for glycerol oxidation in base-free aqueous solution. Free glyceric acid formed (with 68.3% selectivity and 90.4% conversion of glycerol) on Pt/S-MWNTs in base-free solution. While dihydroxyacetone formed firstly in an aqueous solution of NaOH/glycerol=2:1 and the cleavage C–C bonds (catalyzed by alkali) arise severely.