摘要
传统的ZSM-5沸石受其特有微孔孔径的限制,不但影响大分子进入微孔孔道内进行反应,而且也使得大分子反应物和生成物在孔道内的扩散受阻。将ZSM-5沸石纳米化后,通过XRD、SEM和BET等手段对其进行表征,发现纳米ZSM-5沸石具有更小的晶粒和更大的外比表面积;对不同硅铝物质的量比的纳米ZSM-5沸石进行NH3-TPD和Py-IR表征,结果发现低硅铝物质的量比的ZSM-5沸石具有更高的B酸量和L酸量,且强酸量在ZSM-5沸石上占有很高的比例。随后在温度为75℃、时间为30 min、甲缩醛与三聚甲醛的摩尔比为2、催化剂加入量为2%(质量分数)的条件下,考察不同催化剂对反应活性的影响,发现外比表面积大且酸量大的纳米ZSM-5具有更优的催化活性。
Application of traditional ZSM-5 zeolites is limited by their characteristic micropore size,which not only affects the entrance of macromolecules into micropore channels for reaction,but also hinders the diffusion of reactants and products in the pores.A series of nanocrystal and larger crystal ZSM-5 zeolites were characterized by XRD,SEM,and BET.It was found that the nano-ZSM-5 zeolites had smaller size and larger external specific surface area.At the same time,NH3-TPD and Py-IR characterization of nano-ZSM-5 zeolites with different silica to aluminum ratios were carried out.The results showed that ZSM-5 zeolite with low silicon-aluminum ratio had higher B acid content and L acid content,the amount of strong acid sites on zeolite accounted for a high proportion.The catalysts were tested in an autoclave reaction system under the condition of temperature 75℃,time 30 min,dimethoxymethane to trioxane molar ratio 2,catalyst loading 2%(wt).It was found that nano-ZSM-5 with large external specific surface area and amount of acid sites had better catalytic activity.
作者
杨义
付超超
赵葛新
姜艳
YANG Yi;FU Chao-chao;ZHAO Ge-xin;JIANG Yan(SINOPEC Catalyst Dalian Co.,Ltd.,Dalian 116043,China;Fushun Division of SINOPEC Catalyst Co.,Ltd.,Fushun 113122,China)
出处
《当代化工》
CAS
2020年第11期2495-2498,共4页
Contemporary Chemical Industry
