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，分别采用浸渍法和离子交换法制备了Cu负载MCM-41（浸渍法，Cu/MCM-41 ;离子交换法; Cu-NaMCM-41，Cu-HMCM-41）。以MCM-41分子筛为载体，以分子筛和非晶态氧化物为载体，制备了Cu/MCM-41分子筛催化剂，并将其用于苯的液相氧化反应。在本研究的催化剂中，Cu离子交换的HMCM-41（Cu-HMCM-41）具有最高的苯酚生成催化活性。结果表明，Cu/MCM-41催化苯氧化反应中存在过氧化氢的积累，V/MCM-41催化苯液相氧化制苯酚反应中，以O2为氧化剂，抗坏血酸为还原剂。在所研究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浸渍量、抗坏血酸用量、溶剂中乙酸浓度对苯酚收率的影响。在V/SiO_2催化苯氧化过程中，观察到H_2O_2的生成，发现H_2O_2的生成量与苯酚的产率密切相关。V/SiO_2催化剂在含抗坏血酸的醋酸水溶液中浸出后，得到的含V物种的均相滤液的电子吸收光谱证实了滤液中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.