Preparation And Catalytic Properties Of Supported Copper Oxide Based Nanocatalysts

In recent years,mutagenesis,carcinogenesis and teratoeenesis caused by the circulation of harmful chemicals in environment have gradually attracted more and more attention.P-nitrophenol?4-NP?is one of these harmful chemicals which is difficult to be degraded,meanwhile,the unavoidable use of it as an intermediate in modern industrial and agricultural brings unbearable pressure to environment.Therefore,it is of great importance to seek an efficient and environmental friendly treatment of 4-NP.It has been found that 4-NP can be converted into an important material of analgesics and antipyretics called p-aminophenol?4-AP?by using metal nanoparticles?NPs?as catalysts in the catalytic hydrogenation process.Traditional metal nanocatalysts for catalytic hydrogenation of 4-NP usually use expensive and rare noble metals?gold,silver,platinum,palladium,etc.?.Although these noble metal nanocatalysts exhibit outstanding performance in catalytic reactions,the high cost and scarcity limit their wide-scale use.Therefore,searching for a suitable non-noble metal nanocatalyst instead of a noble metal one is an urgent issue.In addition,smaller metal NPs have a tendency to aggregate,resulting in a remarkable deactivation in their catalytic activity,and also smaller particles are difficult to be separated from the reaction media and recycled.To solve these problems,metal NPs are needed to be immobilized on to the surface of a series of the supports.Herein,we have synthesized supported copper oxide-based nanocatalysts using three different supports by deposition-precipitation method and calcination method.The obtained products were characterized by a variety of techniques,and their catalytic activities were also evaluated by the hydrogenation reaction of 4-NP.The specific research results are as follows:?1?TiO₂ nanosponge?TiO₂-NSP?support with large specific surface area has been synthesized by a sol-gel process using natural cellulose as a template.The hydroxyl groups on the surface of TiO₂-NSP are beneficial to immobilize Cu²⁺.CuO/TiO₂-NSP composite nanocatalyst?CT-x?was prepared by loading CuO on the surface of TiO₂-NSP through deposition-precipitation method and calcination method.The results show that the CT-x are pure phase and the CuO NPs are well dispersed on the surface of the support TiO₂,CT-12exhibits the highest catalytic activity for 4-NP hydrogenation,CT-12 can also be used to the catalytic hydrogenation of methyl orange?MO?.?2?Holey g-C₃N₄ nanosheet?CNHS?support has been prepared by high temperature polymerization and thermal treating method using melamine as a raw material.The coordination between N in CNHS and Cu²⁺enable the interaction between CuO and CNHS in the CuO/CNHS composite nanocatalysts?CC-x?.The experimental results show that CC-x with uniform morphology contain no impurities and CC-12 shows the highest catalytic activity and good cycle stability for 4-NP hydrogenation.In addition,CC-12 has the ability to catalyze the hydrogenation of MO.?3?Three-dimensional flower-like magnesium silicate?MSNF?support with large specific surface area and porous structure has been prepared by a simple solvothermal method.The adsorption properties and the surface silanol of MSNF can assist the immobilization of Cu²⁺on the surface of MSNF during the deposition-precipitation process.The CuO/MSNF composite nanocatalysts?CM-x?with stability and good dispersion can be successfully prepared through the following calcining process.It has been estimated that the hydrogenation reaction of 4-NP can be completed rapidly with only a small amount of CM-12,and CM-12can catalyze hydrogenation of MO rapidly as well.