Catalytic combustion of toluene over mesoporous Cr2O3-supported platinum catalysts prepared by in situ pyrolysis of MOFs

Three-dimensional penetrating Pt-loaded mesoporous Cr2O3 catalysts (Pt@M-Cr2O3) were synthesized by pyrolysis of MIL-101-Cr containing pre-impregnated Pt NPs. Physicochemical properties of the samples were characterized by means of various techniques including XRD, Raman, BET, SEM, TEM, XPS and H-2-TPR, and their catalytic activities were evaluated by toluene combustion compared with commercial Cr2O3 (C-Cr2O3). It is found that mesoporous Cr2O3 (M-Cr2O3) support with a high surface area of 77.40 m(2)/g is composed of vast Cr2O3 nanocrystallites. With pre-impregnated Pt loading in MIL-101-Cr, it partly restrains the aggregation of Pt NPs during the pyrolysis of MOFs to M-Cr2O3 and strengthens the interaction between Pt NPs and Cr2O3 nanocrystallites. The obtained 0.82Pt@M-Cr2O3 exhibits the best catalytic performance of toluene combustion, giving 120, 140 and 144 degrees C of T-10%, T-50% and T-90% under 1000 ppm of toluene at space velocity of 20,000 mL/(g h), respectively. The investigation of the different space velocity, the catalytic stability and the effect of water vapor on catalytic activity over 0.82Pt@M-Cr2O3 have confirmed the good catalytic performance. Furthermore, the studies of in situ DRIFTS indicate toluene degradation over 0.82Pt@M-Cr2O3 is via benzoate species by rapidly transforming of benzylic and aldehydic species, and then oxidized to maleic anhydride in an aromaticring opening reaction, finally is decayed to CO2 and H2O.