Catalytic Decomposition Of N₂O And Selective Oxidation Of Benzyl Alcohol Over Transition Metal Catalysts

N₂O is one of the green-house gases limited by Kyoto Protocol,whose emission is increasing year by year.Catalytic decomposition of N₂ O into N₂ and O₂ is an effective method for N₂ O destruction.In this thesis,Co-Al and Mn-Co-Al composite oxides were prepared by sol-gel method and applied for N₂ O catalytic decomposition.The effect of catalyst preparation parameters such as compositions,pH values of mother liquid,amount of complexing agent and dosage of K additives on catalytic activity was investigated.These catalysts were characterized by means of techniques such as XRD,BET,SEM,H₂-TPR,O₂-TPD and XPS.The results show that:?1?The optimal catalyst of K/Co-Al catalyst was prepared with Co2.5Al0.5O4 with mother liquid pH value of 2,molar ratio of citric acid to metal ion of 1,and K/Co molar ratio of0.02.?2?The optimal catalyst of K/Mn-Co-Al catalyst was prepared with Mn_0.2Co_2.3Al_0.5O₄ with mother liquid value of 2,and K/?Co+Mn?molar ratio of 0.02.?3?In contrast to bare oxide,the addition of appropriate amount of K weakened the metal-oxygen bond on the catalyst surface,accelerated the removal of oxygen species,and enhanced the catalytic activity and stability.Benzaldehyde is an important intermediate for organic synthesis,widely used in medicine,dyes,spices and other industries.Selective oxidation of benzyl alcohol is an effective method for benzaldehyde preparation.In this thesis,Mn-Al and Cu-Mn-Al composite oxides were prepared by sol-gel method.The metal-organic-framework?MOF?of Cu₃?BTC?₂ was synthesized by hydrothermal method and calcined to form its derivatives.They were used as catalysts for selective oxidation of benzyl alcohol,with O₂ or H₂O₂ as the oxidant.The effect of catalyst preparation parameters and reaction conditions on catalytic activity was investigated.The following results are obtained:?1?When toluene was used as solvent and O₂ as oxidant at 80 °C for 5 h,the conversion of benzyl alcohol over Mn2 Al and Cu0.3Mn0.7Al2 catalysts was 36.6% and 40.9%,respectively.The selectivity of benzaldehyde was 100%.?2?When water as solvent was 10 ml,benzyl alcohol 1ml,H₂O₂ 4 ml,catalyst 50 mg,75.4% conversion of benzyl alcohol and 83.5% selectivity of benzaldehyde can be reachedat 70 °C for 1 h over Cu₃?BTC?₂ prepared by using an autoclave rotated at 110 °C for 24 h.?3?When Cu₃?BTC?₂ calcined under N₂ at 700 °C?labeled as N₂-700 °C?was used as catalyst,water as solvent?10 ml?,benzyl alcohol 1ml,H₂O₂ 4 ml,catalyst 50 mg,benzyl alcohol conversion was 57.8% and benzaldehyde selectivity 86.3% at 70 ° C for 1 h.Unforturenately,the selectivity of benzaldehyde reduced to 68.6% after 5 times of repeated running?reaction for 3 h each time?.