Identifying and controlling the acid site distributions in mordenite zeolite for dimethyl ether carbonylation reaction by means of selective ion-exchange,Catalysis Science & Technology

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Identifying and controlling the acid site distributions in mordenite zeolite for dimethyl ether carbonylation reaction by means of selective ion-exchange
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2020-06-05 , DOI: 10.1039/d0cy00125b
Shiping Liu _{1,

2,

3,

4,

5} , Hongchao Liu _{1,

2,

3,

4,

5} , Xiangang Ma _{1,

2,

3,

4,

5} , Yong Liu _{1,

2,

3,

4,

5} , Wenliang Zhu _{1,

2,

3,

4,

5} , Zhongmin Liu _{1,

2,

3,

4,

5}

Affiliation

As Brønsted acid sites in different types of channels exhibit distinct catalytic behaviors in the dimethyl ether (DME) carbonylation reaction over acidic mordenite (H-MOR) zeolites (e.g. acid sites in 8-membered ring channels for carbonylation reaction, acid sites in 12-membered ring channels for methanol-to-hydrocarbons reactions), the identification and regulation of acid site distribution in mordenite zeolites are of great importance to improve the catalytic performance. In this work, we employ the selective ion-exchange method to identify and control the acid site distribution in mordenite zeolites, and the chemical properties of acid sites in different channels are investigated by NH₃-TPD and CD₃CN FT-IR. Additionally, the effect of selective ion-exchange on the catalytic performance of DME carbonylation reaction is also discussed. The selective ion-exchange is realized by using tetramethylammonium (TMA⁺) ions, which can selectively remove the counter ions in the 12-membered ring channels but are inaccessible to the counter ions in 8-membered ring channels due to the steric hindrance. The selective ion-exchange reveals that the relative amounts of acid sites in 12-membered ring channels and 8-membered ring channels are 68% and 32%, respectively. Interestingly, it is found that introducing TMA⁺ into H-MOR zeolites significantly improves the catalytic activity and stability in DME carbonylation reaction as a result of depressing the methanol-to-hydrocarbons reactions. The 3TMA-H-MOR catalyst shows high stability for 210 hours on stream. The present work opens a new avenue for designing carbonylation catalysts with excellent stability in DME carbonylation reaction.

中文翻译：

通过选择性离子交换识别和控制丝光沸石用于二甲醚羰基化反应的酸位分布

由于不同类型通道中的布朗斯台德酸位点在二甲基醚（DME）羰基化反应中比酸性丝光沸石（H-MOR）沸石表现出不同的催化行为（例如，用于羰基化反应的8元环通道中的酸点，在12-分子环通道用于甲醇与烃的反应），鉴定和调节丝光沸石分子筛中的酸位分布对于提高催化性能具有重要意义。在这项工作中，我们采用选择性离子交换方法来识别和控制丝光沸石中酸位的分布，并通过NH ₃ -TPD和CD ₃研究了不同通道中酸位的化学性质。CN FT-IR。此外，还讨论了选择性离子交换对DME羰基化反应催化性能的影响。选择性离子交换是通过使用四甲基铵（TMA ⁺）离子实现的，该离子可以选择性地除去12元环通道中的抗衡离子，但由于空间位阻而无法接近8元环通道中的抗衡离子。选择性离子交换表明，十二元环通道和八元环通道中酸位的相对量分别为68％和32％。有趣的是，发现引入TMA ⁺H-MOR沸石的加入可显着提高DME羰基化反应的催化活性和稳定性，因为它可降低甲醇与烃类的反应。3TMA-H-MOR催化剂在运行中显示210小时的高稳定性。本工作为设计在DME羰基化反应中具有优异稳定性的羰基化催化剂开辟了一条新途径。

更新日期：2020-07-21

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