A hydrothermal route was exploited to prepare high-silica H-ZSM-5 as well as H-[B]-ZSM-5 zeolites, and the boron-modified type was then desilicated with alkaline treatment. The properties of catalysts were investigated by different techniques, and the catalytic performance was evaluated in the methanol to propylene reaction. The effects of three critical desilication parameters, including the alkali concentration, temperature, and treatment time were evaluated on propylene selectivity and mesopore volume. The results of characterizations evinced that the incorporation of B in the H-ZSM-5 zeolite reduced the total surface area as well as the pore volume of the H-[B]-ZSM-5 sample and increased the external surface area. Furthermore, a significant increase in the weak acid site density for the boron-containing specimen was observed. Also, the external surface area and mesopore volume of the desilicated specimens underwent an increment, while the micropore volume was almost constant. As opposed to the H-[B]-ZSM-5 catalyst, the optimum desilicated catalyst exhibited higher selectivity to propylene (48.8 vs. 40.7%) and total light olefins (76.9 vs. 71.2%), and a higher ratio of propylene to ethylene (5.66 vs. 4.15). The optimum catalyst had a higher lifetime in the MTP reaction (867 h) as opposed to the microporous H-[B]-ZSM-5 catalyst (498 h).

中文翻译：

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通过脱硅法制备分级 H-[B]-ZSM-5 沸石作为甲醇转化丙烯的高选择性催化剂

采用水热法制备高硅H-ZSM-5和H-[B]-ZSM-5沸石，硼改性型经碱处理脱硅。通过不同的技术研究了催化剂的性能，并评估了其在甲醇制丙烯反应中的催化性能。评估了三个关键脱硅参数（包括碱浓度、温度和处理时间）对丙烯选择性和中孔体积的影响。表征结果表明，在 H-ZSM-5 沸石中加入 B 减少了 H-[B]-ZSM-5 样品的总表面积和孔体积，并增加了外表面积。此外，观察到含硼样品的弱酸位点密度显着增加。还，脱硅试样的外表面积和中孔体积增加，而微孔体积几乎不变。与 H-[B]-ZSM-5 催化剂相比，最佳脱硅催化剂对丙烯（48.8% vs. 40.7%）和总轻烯烃（76.9% vs. 71.2%）表现出更高的选择性，以及更高的丙烯与乙烯（5.66 对 4.15）。与微孔 H-[B]-ZSM-5 催化剂（498 小时）相比，最佳催化剂在 MTP 反应（867 小时）中具有更高的寿命。丙烯与乙烯的比例更高（5.66 对 4.15）。与微孔 H-[B]-ZSM-5 催化剂（498 小时）相比，最佳催化剂在 MTP 反应（867 小时）中具有更高的寿命。丙烯与乙烯的比例更高（5.66 对 4.15）。与微孔 H-[B]-ZSM-5 催化剂（498 小时）相比，最佳催化剂在 MTP 反应（867 小时）中具有更高的寿命。