National Institute of Clean-and-Low-Carbon Energy (NICE), 102211, Beijing, China.
Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, 100871, Beijing, China.
Nat Commun. 2019 Sep 25;10(1):4348. doi: 10.1038/s41467-019-12285-4.
The shape-selective catalysis enabled by zeolite micropore's molecular-sized sieving is an efficient way to reduce the cost of chemical separation in the chemical industry. Although well studied since its discovery, HZSM-5's shape-selective capability has never been fully exploited due to the co-existence of its different-sized straight channels and sinusoidal channels, which makes the shape-selective p-xylene production from toluene alkylation with the least m-xylene and o-xylene continue to be one of the few industrial challenges in the chemical industry. Rather than modifications which promote zeolite shape-selectivity at the cost of stability and reactivity loss, here inverse Al zoned HZSM-5 with sinusoidal channels predominantly opened to their external surfaces is constructed to maximize the shape-selectivity of HZSM-5 sinusoidal channels and reach > 99 % p-xylene selectivity, while keeping a very high activity and good stability ( > 220 h) in toluene methylation reactions. The strategy shows good prospects for shape-selective control of molecules with tiny differences in size.
沸石微孔的分子筛分所实现的择形催化是降低化工分离成本的有效方法。尽管自发现以来已经进行了充分的研究，但由于其不同大小的直通道和正弦通道共存，HZSM-5 的择形能力从未得到充分利用，这使得从甲苯烷基化反应中以最小的间二甲苯和邻二甲苯生产对二甲苯仍然是化工行业的少数工业挑战之一。这里构建了反位 Al 分区 HZSM-5，其正弦通道主要通向外部表面，以最大化 HZSM-5 正弦通道的择形能力，并达到对二甲苯选择性>99%，同时在甲苯甲基化反应中保持非常高的活性和良好的稳定性（>220 h），而不是以稳定性和反应性损失为代价来促进沸石择形性的修饰。该策略为具有微小尺寸差异的分子的择形控制展示了良好的前景。
