【摘要】 为揭示蜂窝陶瓷催化臭氧化降解水中硝基苯的反应机理,从臭氧与非均相表面的作用方式上推测催化氧化过程中HO.的引发历程.采用XRD、FT-IR和SEM等手段对催化剂进行表征,结果表明,催化剂主晶相为2MgO.2Al2O3.5SiO2,是标准的α-堇青石;催化剂表面存在表面羟基,其含量为9.13×10-6mol/m2,催化剂表面的pHzpc=6.60,本实验条件下(pH=6.87),表面羟基是以游离羟基或氧负离子形式存在.催化剂含有碱性氧化物MgO及酸性氧化物Al2O3和SiO2,其表面存在金属离子Lewis酸位和表面羟基.当催化剂在水溶液中进行催化臭氧化反应时,Lewis酸优先与水配位而使水离解形成表面羟基,而臭氧与金属离子Lewis酸配位作用就会大大降低.臭氧会进一步与表面羟基形成配位键和氢键,而后经由—HO2-、O3·-和HO3·等活性物质生成HO·.更多还原

【Abstract】 In order to investigate the mechanism of ceramic honeycomb catalytic ozonation for the decomposition of nitrobenzene in aqueous solution,we discussed the possible pathway of HO· initiation from the interaction of ozone and heterogeneous surface in the process of catalytic ozonation.The surface characteristics of ceramic honeycomb were determined with XRD,FT-IR and SEM.Results indicate that the main crystal phase of ceramic honeycomb is 2MgO·2Al2O3·5SiO2,which is the standard structure of α-cordierite.Experimental results demonstrate that surface hydroxyl groups exist on the surface of ceramic honeycomb catalyst with density of 9.13×10-6mol/m2.pHzpc of the surface of catalyst is 6.60,which is presented as dissociate hydroxyl and oxygen anion under the present experimental condition(pH=6.87).Lewis acid sites and surface hydroxyl groups form on the surface of catalyst because the ceramic honeycomb is composed of alkaline MgO and acid Al2O3 and SiO2.When ceramic honeycomb catalytic ozonation happens in aqueous solution,Lewis acid coordinates with water molecular in priority to create surface hydroxyl groups.However,the possibility of ozone reacting with Lewis acid sites will decline.Furthermore,ozone will react with the surface hydroxyl groups to form coordinated bond and hydrogen bond,then create HO· via some radical species,such as —HO2-,O·-3,HO·3 and so on.更多还原