Synthesis,Characterization Of Supported Metal-catalysts And Investigation Of Their Catalytic Hydrogenation Of Levulinic Acid To Gamma Valerolactone

In this work,various metal based catalysts such as Cu,Ni,Mo,Co and W supported on activated carbon were prepared by using the incipient wetness method.The aim of this synthesis is to find the non noble metal based catalysts with catalytic activity comparable to that of noble metal based catalyst mostly used in catalytic hydrogenation of levulinic acid（LA）toγ-valerolactone（GVL）.GVL serves as a platform for fuels,fuel additives and chemicals.The evaluation of their catalytic activity showed that 10 wt%Ni/AC is the only promising catalyst to produce valuable GVL through LA hydrogenation.BET,XRD and TEM techniques were used for 10 wt%Ni/AC catalyst characterization.BET reveals the interaction between nickel nitrate precursor and support which led to the increase of catalyst dimensions in comparison with those of support.S_BETET is 747.2500 m²/g for 10 wt%Ni/AC catalyst whereas that is 650.1889 m²/g for pure activated carbon.From TEM,the average Nickel particle size is 21.08 nm and 24,39 nm for fresh and spent catalyst respectively.XRD characterization displays the presence of metallic Nickel at 44.509°（111）,51.883°（200）,and76.367°（220）for both fresh and used catalysts after 5 recycling.This result indicates the total conversion of Nickel oxides（NiO）to metallic Nickel and no re-oxidation of catalyst.The study of the effect of calcinations temperature showed that the increase of temperature involves the increase of the pore size and the sample of 10 wt%Ni/AC catalyst must be reduced in hydrogen at 450°C.The catalytic test was conducted for hydrogenation of levulinic acid to gamma valerolactone,in batch autoclave by using molecule H₂ as hydrogen source.Reactions conditions are:LA（2g）,catalyst loading（0.5 g）,T=150°C,Time=3 h,1,4-dioxane as solvent;GC and GC-MS were used to analyze the mixture products.Among all catalysts,10wt%Ni/AC catalyst exhibited the higher catalytic activity.100%conversion of LA and100%selectivity towards GVL were obtained.The study of the effect of reaction temperature,initial hydrogen pressure,reaction time demonstrates a significant influence of these reaction parameters on catalytic activity.Furthermore,the gradual decrease of conversion is observed during reusability of catalyst.It decreases from 100%to 65%after recycling for 5 times.In this Thesis,the results show that 10 wt%Ni/AC is non-precious,inexpensive metals based catalyst which competes with noble metal based catalysts for hydrogenation of LA to GVL.10 wt%Ni/AC catalyst can also be used for industrial applications to produce GVL.However,a supplementary study is recommended in order to improve the 10 wt%Ni/AC catalytic stability.