Preparation Of Zirconia-fe And Cu Aerogel Catalysts And Catalytic Activity For Phenol Hydroxylation

Zirconium oxide?ZrO₂?aerogel has high specific surface area,high porosity,excellent thermal stability,chemical stability and catalytic performance.It has broad application prospects and development,and can beused as catalyst,efficient insulation materials,fuel cell electrode materials,etc.Many types of catalysts for the hydroxylation of phenol have been prepared and characterized.Research on new catalysts has also been carried out.The development of new environmental friendly catalyst with high conversion and excellent selectivity for benzenediol is the interesting issue for many researchers.In this paper,low-cost zirconium oxychloride is used as precursor.The mixed solution of ethanol and water is used as solvent.Propylene oxide is adding as a gel promoter to capture hydrogen ions in the system,promoting hydrolysis and polymerization of hydrated metal ions to form a metal oxide gel;adding formamide to form a homogeneous polymer with higher polymerization degree of Zr in the system;the surface modifier is used to enhance the structural strength.By designing orthogonal experiments,the optimal preparation conditions were found,and zirconia aerogels with higher specific surface area and uniform pore size distribution were prepared.The zirconia-loaded copper-iron aerogel catalyst were prepared by impregnating zirconia,and the catalytic performance of phenol hydroxylation was studied.The zirconia aerogels were characterized by scanning electron microscopy?SEM?,N₂ adsorption/desorption,X-ray diffraction?XRD?,etc.The conversionof phenol and benzenediol selectivity of phenol hydroxylation reaction were analyzed by liquid chromatography.The main results are as follows:?1?Analyse the orthogonal test results,the optimum process parameters for preparing ZrO₂ aerogel were molar ratio Zr:formamide:propylene oxide=1:1.5:12,and the volume ratio of ethanol to water was 3:1,modified the structure by a mixed solution of 15%volume of ethyl orthosilicate and ethanol.Zirconia aerogelwith pecific surface area 623 m²/g and uniform pore diameter was obtained.?2?The zirconia-loaded copper aerogel catalyst has the best catalytic performance,theconversion of phenol is 71.5%,and The ratio of catechol to hydroquinone is close to 3:2.