As the process of methanol to hydrocarbons (MTH) is catalyzed by acid sites, the regulation of framework aluminum siting and acid distribution in a zeolite catalyst to enhance its performance in MTH is an important and challenging task. In this work, the regulation of framework aluminum siting in H-MCM-22 was achieved through boron incorporation; the relation between catalytic performance and acid distribution was investigated. The results illustrate that the distribution of framework aluminum and Brönsted acid sites among three types of pores in H-MCM-22 can be regulated through adjusting the content of boron incorporated during synthesis, due to the competitive occupancy of various framework T sites between boron and aluminum, whereas the textural properties and overall acid types and amounts are less influenced by boron incorporation. Incorporating a proper content of boron can concentrate the Brönsted acid sites in the sinusoidal channels rather than in the surface pockets and supercages. The acid sites located in the surface pockets and supercages are prone to carbonaceous deposition, whereas those acid sites in the sinusoidal channels are crucial for MTH in the steady reaction stage. Moreover, the acid sites in the sinusoidal channels are favorable to the olefin-based cycle that produces preferentially higher olefins. As a result, the incorporation of proper content of boron delivers the H-MCM-22 zeolite much greater stability and higher selectivity to higher olefins such as propene and butene in MTH than previously reported. These results help to clarify the relation between the catalytic performance of H-MCM-22 in MTH and its acid distribution and then bring forward an effective approach to develop better MTH catalysts by regulating the acid distribution.

中文翻译：

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硼的掺入对H-MCM-22中骨架铝的选择和酸分布的调节及其对甲醇催化碳氢化合物催化性能的影响

由于酸性位点催化了甲醇转化为碳氢化合物（MTH）的过程，因此调节骨架铝的位置和沸石催化剂中的酸分布以增强其在MTH中的性能是一项重要且具有挑战性的任务。在这项工作中，通过掺入硼来控制H-MCM-22中框架铝的位置。研究了催化性能与酸分布之间的关系。结果表明，通过调节合成过程中掺入的硼含量，可以调节H-MCM-22中三种类型的孔中骨架铝和布朗斯台德酸位的分布，这是由于硼和铁之间的各种骨架T位具有竞争性。铝，而组织性质和整体酸的种类和含量受硼掺入的影响较小。掺入适量的硼可以使布朗斯台德酸性位点集中在正弦形通道中，而不是表面凹坑和超笼中。位于表面囊和超笼中的酸位易于碳质沉积，而在正弦通道中的那些酸位对于稳定反应阶段中的MTH至关重要。此外，正弦通道中的酸位点有利于优先产生更高烯烃的基于烯烃的循环。结果，掺入适当含量的硼使H-MCM-22沸石在MTH中比以前报道的具有更高的稳定性和对较高烯烃如丙烯和丁烯的更高选择性。