Catalytic Performance Of Hydrotalcite-derived Catalysts In Transfer Hydrogenation Of Unsaturated Carbonyl Compounds

As a renewable carbon source,biomass is renewable,low-polluting,and widely distributed.Biomass molecules contain a large number of unsaturated functional groups(C=C,C=O,etc.),which can be used to many high value-added products such as fuel,fine chemicals and other high value-added products by catalytic hydrogenation,The hydrogenation methods of biomass molecules are mainly divided into direct hydrogenation and transfer hydrogenation.Direct hydrogenation uses hydrogen as the hydrogen source.The reaction process requires a higher reaction pressure,which is likely to cause excessive hydrogenation and reduce the selectivity of the target product.Following the Meerwein-Ponndorf-Verley(MPV)mechanism,transfer hydrogenation takes formic acid,alcohols and other hydrogen donors as hydrogen sources,compared with direct hydrogenation,which is easier to control hydrogenation process and the product has higher selectivity.A series of CuNiAl catalysts were utilized to catalytic transfer hydrogenation(CTH)of levulinic acid to ?-valerolactone which prepared by direct reduction of CuNiAl-LDH precursors that were obtained by coprecipitation method.XRD,N2 adsorption-desorption,ICP,XPS,TEM,and NH3/CO2-TPD were used to characterize the prepared catalysts.The effects of active components,reduction temperature,hydrogen donor,reaction temperature and reaction time on catalytic transfer hydrogenation were studied.The results show that the addition of Cu to the catalyst can generate Cu Ni alloy,which is due to the interaction between Cu and Ni,significantly improves the catalytic activity.The CuNiAl catalyst with molar ratio of 1:14:5 reduced at 500 oC exhibited the highest CTH activity.In the investigation of hydrogen-donating solvents,it was found that secondary alcohols had higher activity than primary alcohols,and isopropanol had the best activity.The higher the reaction temperature and the longer the reaction time,the more active H provided by the hydrogen-donating solvent,which in turn promotes the formation of ?-valerolactone.After reacting at 190 oC for1 h,levulinic acid was completely reacted,and the selectivity of ?-valerolactone reached86.0%.A series of MgAl-MoO catalysts were utilized to catalytic transfer hydrogenation(CTH)of cinnamaldehyde to cinnamyl alcohol which prepared by calcining Mg Al-Mo LDH precursors that were obtained by coprecipitation method.The effects of active components,Mo source,calcination temperature,reaction temperature,and reaction time on catalytic transfer hydrogenation were studied.The results showed that Mo-was successfully intercalated into Mg Al LDH.By comparing different catalysts,it was found that molybdenum oxide had higher selectivity for cinnamyl alcohol.The Mg Al-MoO catalyst with molar ratio of 3:1:1calcinedat 500 oC exhibited the highest CTH activity,which is prepared with ammonium molybdate as the Mo source.In order to control the transfer hydrogenation of cinnamaldehyde to cinnamyl alcohol,it is necessary to select an appropriate reaction temperature and time.After reacting at 160 oC for 1 h,the conversion of cinnamaldehyde and the selectivity of cinnamyl alcohol reached 97.8% and 96.3%.