钨酸铋担载钯纳米粒子光催化甲苯及其衍生物到醛的氧化反应（英文）

发布时间：2018-05-19 16:13

本文选题：花状钨酸铋 + 甲苯氧化　；参考：《催化学报》2017年03期

【摘要】：甲苯及其衍生物的选择性氧化是化学工业中重要的一环.氧化产物醛、酮和酸类化合物是各种农药、染料、防腐剂、阻燃剂、香料、塑料的合成中间体.在传统的化工过程中,通常在苛刻的条件下,如高温、高压以及酸性溶剂中进行甲苯的选择性氧化.光催化有机合成作为一种"绿色"的合成方法受到越来越多的关注.我们发现钨酸铋作为可见光响应的光催化剂,可以利用氧气作为氧化剂,对甲苯及其衍生物进行催化氧化反应.通过调节水热法合成钨酸铋的酸碱条件,控制其成核生长过程,改变其形貌,发现在pH值为0.49时,得到花状钨酸铋粉末活性最高.X射线衍射、扫描电镜、紫外可见吸收光谱和比表面测定结果发现,花状钨酸铋粉末表现出最佳的甲苯氧化活性很可能是与它最大的比表面积有关系.为了进一步提高催化的活性,我们将助催化剂担载在钨酸铋粉末上,发现Pd的担载量为0.1wt%时甲苯氧化反应活性最高.将邻、间、对位甲基取代以及对位甲氧基和氯取代的甲苯衍生物进行反应,发现均可高选择性地得到目标产物.在加入电子牺牲剂硝酸银和空穴牺牲剂草酸铵到反应体系后,发现反应被完全禁阻,说明在甲苯氧化反应过程中电子和空穴都起到了相应的作用.通过电化学测试发现,钯作为助催化剂担载在钨酸铋表面后,产生更强的氧化和还原信号,说明其在电子和空穴发生反应的过程中都起到了相应的促进作用.由此推测,在甲苯的氧化反应中,钨酸铋材料表面吸收可见光,产生光生电子和空穴,而钯的担载则促进了电子和空穴进行氧气还原和甲苯氧化的过程.
[Abstract]:Selective oxidation of toluene and its derivatives is an important part of the chemical industry. Oxidation products aldehydes, ketones and acids are synthetic intermediates of pesticides, dyes, preservatives, flame retardants, spices and plastics. The selective oxidation of toluene in traditional chemical processes is usually carried out under harsh conditions, such as high temperature, high pressure and acid solvents. As a green synthetic method, photocatalytic organic synthesis has attracted more and more attention. It is found that bismuth tungstate can be used as a visible photocatalyst to catalyze the oxidation of toluene and its derivatives using oxygen as oxidant. By adjusting the acid-base conditions of hydrothermal synthesis of bismuth tungstate, the nucleation and growth process of bismuth tungstate was controlled and its morphology was changed. It was found that the highest activity of bismuth tungstate powder was obtained at pH 0.49. UV-Vis absorption spectra and specific surface measurements showed that the best toluene oxidation activity of bismuth tungstate powder was probably related to its largest specific surface area. In order to further improve the catalytic activity, the catalyst was supported on bismuth tungstate powder. It was found that the activity of toluene oxidation was the highest when the loading of PD was 0.1 wt%. The reaction of o-, m-, p-methyl-substituted, p-methoxy and chlorinated toluene derivatives shows that the target products can be obtained with high selectivity. After adding electron sacrificial silver nitrate and hole sacrificial ammonium oxalate to the reaction system, it was found that the reaction was completely blocked, indicating that both electrons and holes played a corresponding role in the oxidation of toluene. It was found by electrochemical measurement that palladium as a catalyst supported on the surface of bismuth tungstate produced stronger redox and reduction signals, which indicated that palladium played a corresponding role in the reaction between electrons and holes. It is inferred that in the oxidation of toluene the surface of bismuth tungstate absorbs visible light to produce photogenerated electrons and holes while the loading of palladium promotes the oxygen reduction of electrons and holes and the oxidation of toluene.
【作者单位】：中国科学院大连化学物理研究所;中国科学院大学;
【基金】：supported by the National Natural Science Foundation of China(21322202,21472187) the National Basic Research Program of China(2010CB833300)~~
【分类号】：O643.36

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