Co/TUD-1催化1,2-二苯乙烯环氧化反应

摘要

以乙酰丙酮钴(Ⅱ)为前体,采用原子层沉积法合成了Co/TUD-1催化剂,考察了该催化剂在以O2为氧化剂的1,2-二苯乙烯环氧化反应中的性能；并对催化剂进行了XRD、N2吸附-脱附、漫反射光谱和H2-TPR表征.表征结果显示,当Co负载量(w)小于等于4.0％时,TUD-1分子筛中Co主要以高度分散的CoOx形式存在；当Co负载量大于40％时,分子筛的孔道内外均有大量Co3O4形成.高度分散在分子筛中的CoOx是1,2-二苯乙烯环氧化的高活性组分.与采用浸渍法和水热法制备的催化剂相比,原子层沉积法制备的Co/TUD-1催化剂具有更高的活性.以负载量为4.0％的Co/TJD-1为催化剂,在100℃下反应6 h时,1,2-二苯乙烯转化率为49.3％,环氧化物选择性为96.8％.%Co/TUD-1 catalysts with different Co loadings were synthesized by atomic layer deposition(ALD) method using cobalt acetylacetonate( H) as the precursor and were characterized by means of XRD, N2 adsorption-desorption, DRS and H2-TPR. Activity of the prepared catalysts in epoxidation of Svww-stilbene with oxygen was investigated. The results showed that the Co species on TUD-1 molecular sieves existed mainly in the form of highly dispersed CoOx when the Co content was not more than 4.0%(w), whereas higher Co content would lead to formation of a large amount of Co3O4 clusters outside and inside the channels of the TUD-1 molecular sieves. Compared with the catalysts prepared by impregnation or hydrothermal method with the same Co content, Co/TUD-1 catalyst prepared by ALD method exhibited high activity in epoxidation of trwts-stilbene. Under the conditions of reaction temperature 100 ℃, reaction time 6 h and Co/TUD-1 with Co loading 4.0% as the catalyst, the conversion of frans-stilbene and the selectivity to epoxide were 49.3% and 96.8%, respectively.