Glycerol aerobic oxidation to glyceric acid over Pt/hydrotalcite catalysts at room temperature  

作　　者：Junbo Zhang Xiaolin Li Ming Xu Yusen Yang Yinwen Li Ning Liu Xiaoyu Meng Lifang Chen Shuxian Shi Min Wei 

机构地区：[1]State Key Laboratory of Chemical Resource Engineering,Beijing Advanced Innovation Center for Soft Matter Science and Engineering,Beijing University of Chemical Technology,Beijing 100029,China [2]College of Chemistry and Molecular Engineering and College of Engineering,BIC-ESAT,Peking University,Beijing 100871,China

出　　处：《Science Bulletin》2019年第23期1764-1772,共9页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China (21871021 and 21521005);the National Key Research and Development Program (2017YFA0206804);the Fundamental Research Funds for the Central Universities (buctylkxj01 and XK1802-6)

摘　　要：Glycerol(GLY) aerobic oxidation in an aqueous solution is one of the most prospective pathways in biomass transformation, where the supported catalysts based on noble metals(mainly Au, Pd, Pt) are most commonly employed. Herein, Pt nanoparticles supported on rehydrated MgxAl1-hydrotalcite(denoted as re-MgxAl1-LDH-Pt) were prepared via impregnation-reduction method followed by an in situ rehydration process, which showed high activity and selectivity towards GLY oxidation to produce glyceric acid(GLYA) at room temperature. The metal-support interfacial structure and catalyst basicity were modulated by changing the Mg/Al molar ratio of the hydrotalcite precursor, and the optimal performance was achieved on re-Mg6Al1-LDH-Pt with a GLY conversion of 87.6% and a GLYA yield of 58.6%, which exceeded the traditional activated carbon and oxide supports. A combinative study on structural characterizations(XANES, CO-FTIR spectra, and benzoic acid titration) proves that a higher Mg/Al molar ratio promotes the formation of positively charged Ptd+species at metal-support interface, which accelerates bond cleavage of a-C–H and improves catalytic activity. Moreover, a higher Mg/Al molar ratio provides a stronger basicity of support that contributes to the oxidation of terminal-hydroxyl and thus enhances the selectivity of GLYA. This catalyst with tunable metal-support interaction shows prospective applications toward transformation of biomass-based polyols.Glycerol（GLY） aerobic oxidation in an aqueous solution is one of the most prospective pathways in biomass transformation, where the supported catalysts based on noble metals（mainly Au, Pd, Pt） are most commonly employed. Herein, Pt nanoparticles supported on rehydrated MgxAl1-hydrotalcite（denoted as re-MgxAl1-LDH-Pt） were prepared via impregnation-reduction method followed by an in situ rehydration process, which showed high activity and selectivity towards GLY oxidation to produce glyceric acid（GLYA） at room temperature. The metal-support interfacial structure and catalyst basicity were modulated by changing the Mg/Al molar ratio of the hydrotalcite precursor, and the optimal performance was achieved on re-Mg6Al1-LDH-Pt with a GLY conversion of 87.6% and a GLYA yield of 58.6%, which exceeded the traditional activated carbon and oxide supports. A combinative study on structural characterizations（XANES, CO-FTIR spectra, and benzoic acid titration） proves that a higher Mg/Al molar ratio promotes the formation of positively charged Ptd+species at metal-support interface, which accelerates bond cleavage of a-C–H and improves catalytic activity. Moreover, a higher Mg/Al molar ratio provides a stronger basicity of support that contributes to the oxidation of terminal-hydroxyl and thus enhances the selectivity of GLYA. This catalyst with tunable metal-support interaction shows prospective applications toward transformation of biomass-based polyols.

关 键 词：Rehydrated hydrotalcites Interfacial structure Support basicity Active sites Rate-determining step 

分 类 号：O64[理学—物理化学]