Co/TUD-1催化1,2-二苯乙烯环氧化反应

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4.0%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/TUD-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%。

Epoxidation of trans-Stilbene over Highly Dispersed Co/TUD-1Catalysts

Co/TUD-1 catalysts with different Co loadings were synthesized by atomic layer deposition(ALD) method using cobalt acetylacetonate(Ⅱ) 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 trans-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 trans-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 trans-stilbene and the selectivity to epoxide were 49.3% and 96.8%,respectively.