Preparation And Oxidation-dehydration Catalytic Properties For Glycerol Of CuO_x/Clay Catalyst

Glycerol,as the major by-product,is normally generated in 10 wt.% for every tonne of biodiesel in the transesterification of plant oil or animal fat with methanol.In recent years,the growth of biodiesel as fuel has led to the surplus production and the saturated market of glycerol,which restricts the commercialization of biodiesel.By far,one-pot glycerol oxidehydration to acrylic acid has attracted researchers' attention markedly to solve the surplus glycerol.However,the great challenge is located in the screening applicable materials with the nature of dehydration and redox.Montmorillonite,as 2:1 layered phyllosilicate clay mineral,naturally possesses high cation exchange capacity,strong adsorption capacities and excellent sol-gel swelling capacity.And it is also a kind of solid acidity material with Br?nsted and Lewis acid sites.The acid-activated and salt-treated montmorillonites are usual used as catalyst supports and materials in dehydration reactions because of its low price and nontoxicity.The copper in Cu-based materials shows different valence states(such as 0,+1,+2)and usually remarkable redox activity.And it,which is regarded as the auxiliary or substitution of noble metals,has be applied successfully in organic reactions.In the work,we combined Cu-based materials with montmorillonite and explored cheap and eco-friendly bifunctional nanocomposites characterized by acidity and redox.Then the experiment investigated the influence of phosphoric acid,preparation methods(including NaBH4 reductionglucose reduction and calcine)and loading content of CuO_x.Lastly,we optimized the reaction conditions covering reaction temperature,feed rate and oxygen concentration and discussed the mechanism of glycerol oxidehydration to acrylic acid.With the characterization of apparatus,CuO_x/clay nanocomposites had been successfully synthesized.When the CuO_x/clay was used to catalyze glycerol oxidehydration reaction under the optimum reaction conditions,gycerol conversion reached around 100% and the most yield of acrolein was up to 20%,but only a 3.5% selectivity to acrylic acid.In the experiment,the CuO_x/clay catalyst may serve as model systems to explore synthesis of the cheap and eco-friendly bifunctional nanocomposites and applications for other oxidehydration sequential reactions.