Palladium-chitosan Complex Supported On Molecular Sieve For Kinetic Study On Hydrogenation Of Aromatic Aldehyde And Ketone

With the development of economy and the demand of environmental protection, a kind of catalyst, which both protects environment and improves economic efficiency, needs to be applied in the practically modern chemical industry. The wide use of synthetic polymeric materials brings about tremendous changes for social production and human life. However, their difficult biodegradability causes great destruction to our survival environment. As a kind of natural polymer material, chitosan's merits of good environmental compatibility, rich resources, safe, non-toxic, multi-functional response and low cost make it be used in various fields.Chitosan extracted by deacetylation of chitin, a component of crab shells, insects, and plant cell walls is one of the most abundant natural polysaccharides. Chitosan is also a versatile material which can be easily modified by grafting new specific functional groups on the backbone of the polymer:transformations occur on several functional groups of chitosan but more specifically on-CH2OH and-NH2 groups depending on the substitution mechanism. Thus, chitosan could be considered as a promising carrier for the immobilization of metal complexes and heterogenized metal complexes fixed on the surface of chitosan have high stability and small corrosion resistance.Chitosan-noble metal catalysts have been most used in the catalytic hydrogenation reaction. In order to reduce the loss of effective components and enhance their catalytic properties, chitosan-noble metal catalysts are usually immobilized in inert carriers.A hydrogenated catalyst, palladium-chitosan (Pd-CS) complex supported on molecular sieve was prepared. The palladium-chitosan complex supported on molecular sieve was used to catalyze the hydrogenation of simple aromatic aldehyde and ketone at normal temperature and atmospheric pressure, and GC was used to test the reaction course. Such catalyst could effectively catalyze the hydrogenation of aromatic aldehyde and ketone at room temperature and under atmospheric pressure. Moreover, kinetic behaviors of hydrogenation of aromatic aldehyde and ketone were investigated. The catalyst carrier had an important impact on the catalytic activity. We inspected the influence of the granularity of the catalyst support, the pace, pH and the time of the deposition and the pH after being washed with water to the activity.In the hydrogenation reaction of aromatic aldehyde and ketone, several factors including the N:Pd mole ratio, the selection of solvent, catalyst's amount, the concentration of substrates and the reaction temperature were investigated through single-factor approach and the optimum reaction condition was obtained. In addition, the catalyst is characterized by SEM.The result revealed that ethanol was the best solvent. With the increase of the amount of catalyst, the catalytic activity of the catalyst had been greatly improved and the reaction rate was speeded up. Enhancing reaction temperature was in favor of the conversion of reaction. The catalyst could be recycled and had good stability. The conversion of the reaction was high, and the activation energy was figured out. The reactions were found to be zero order with respect to simple aromatic aldehyde and ketone. A probable reaction mechanism was proposed based on the experiment result.