Preparation of NiMgAl Layered Double Hydroxides and Hydrogen Production from Aqueous-Phase Reforming of Ethylene Glycol

The NiMgAl layered double hydroxides(LDHs) with different n(Ni~(2+))/n(Mg~(2+))/n(Al~(3+))(mole ratios) were synthesized by a coprecipitation method.The phase composition and catalytic performance of Ni-Mg-Al LDHs were characterized by powder X-ray diffraction,H_2-TPR(temperature programmed reduction) and probe reaction of aqueous-phase reforming of ethylene glycol.The results show that the synthesized materials with unitary hydrotalcite phase can be obtained when(n(Ni~(2+))+n(Mg~(2+)))/n(Al~(3+)) is 1.25-6.50.NiMgAl-LDHs derived catalyst(after reaction) was composed of Ni,MgAl-LDHs and AlO(OH) phases.The reduction process for active content Ni of NiMgAl-LDHs involved two stages.The H_2 production rate from aqueous-phase reforming of ethylene glycol(EG) increased with increasing in the reaction temperature and the feeding rate of EG,and decreased with increasing in the reaction pressure.The selectivity of H_2 production could be improved when Mg modified to Ni/Al hydrotalcite,which was related to the basic of supporters.The H_2 selectivity decreased and the alkanes selectivity increased with increasing the Ni contents.Considering the selectivity and the activity of Ni based catalysts,we found that the catalytic performance of NiMgAl-LDHs derived catalyst could be superior.