Design of Catalyst for Phenol Synthesis by Direct Oxygenation of Benzene

以MCM-41和含铝MCM-41(NaMCM-41，HMCM-41)为载体，采用浸渍和离子交换法制备了铜负载MCM-41(浸渍；离子交换；铜-NaMCM-41，铜-HMCM-41)。将负载铜的MCM-41与负载于沸石和无定形氧化物上的铜催化剂一起用作苯液相氧化催化剂。在所研究的催化剂中，铜离子交换的HMCM-41(Cu-HMCM-41)对苯酚的催化活性最高。发现在铜负载的MCM-41催化苯氧化过程中会产生过氧化氢。以O2为氧化剂，抗坏血酸为还原剂，V负载的氧化物催化苯液相氧化制苯酚。在所考察的各种无机氧化物载体中，以SiO_2为载体的V催化剂(V/SiO_2)对苯酚的生成具有较高的催化活性。考察了V的浸渍用量、抗坏血酸的用量和溶剂中CH3COOH的浓度对苯酚产率的影响。在V/SiO_2催化苯氧化过程中观察到了H_2O_2的生成，H_2O_2的生成量与苯酚的产率密切相关。从V/SiO_2催化剂上浸出的含有V物种的均相滤液在含有抗坏血酸的醋酸水溶液中的电子吸收光谱证实了滤液中有H_2O_2的存在。

The Cu-supported MCM-41 (impregnation, Cu/MCM-41 ; ion-exchange ; Cu-NaMCM-41, Cu-HMCM-41) was prepared using MCM-41 and Al-containing MCM-41 (NaMCM-41, HMCM-41) as supports by both the impregnation and ion-exchange methods. The Cu-supported MCM-41, together with the Cu catalysts supported in zeolites and amorphous oxides, were used as catalysts for the liquid-phase oxidation of benzene. The Cu ion-exchanged HMCM-41 (Cu-HMCM-41) had the highest catalytic activity for phenol formation among the catalysts in this study. Hydrogen peroxide was found to accumulate during the benzene oxidation catalyzed by the Cu-supported MCM-41.The V supported oxides were found to catalyze the liquid-phase oxygenation of benzene to phenol using O2 as an oxidant and ascorbic acid as a reductant. The V catalyst (V/SiO_2) supported on SiO_2, among various inorganic oxides investigated as a support, had a high catalytic activity for phenol formation. The influences of the V amount impregnated, the amount of ascorbic acid, and the concentration of CH_3COOH in the solvent on the yield of phenol were investigated. The formation of H_2O_2 was observed during the benzene oxidation catalyzed by V/SiO_2 and the amount of the formed H_2O_2 was found to be closely related to the yield of phenol. The electronic absorption spectra of the homogeneous filtrate including V species, leached from the V/SiO_2 catalyst in the aqueous acetic acid solvent containing ascorbic acid, confirmed the presence of H_2O_2 formed in the filtrate.