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<p>The alkylation of toluene to <i>p</i>-xylene (PX) was considered a very promising route for synthesizing PX, owing to advantages such as high selectivity and low cost. Modified ZSM-5 zeolites were widely used catalysts, and achieving controlled modification drove significant research efforts. This work employed co-modification of ZSM-5 with B<sub>2</sub>O<sub>3</sub> and MgO, where MgO deposition was designed to exploit both the formation of bulky Mg<sup>2+</sup>-citrate chelates and electrostatic interactions between these anionic chelates and electron-deficient boron sites in surface B<sub>2</sub>O<sub>3</sub>, aiming to preferentially anchor Mg species at external zeolite surfaces. This approach achieved simultaneous acidity regulation and selective elimination of external acid sites while suppressing MgO-induced pore blocking, consequently yielding catalysts with high alkylation activity and PX selectivity. At loadings of 3% B<sub>2</sub>O<sub>3</sub> and 5% MgO, the catalyst delivered optimal performance with 13% toluene conversion and 80% PX selectivity at 400&#xa0;°C.</p>

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Regulating magnesium oxide position in co-modification to promote the alkylation of toluene to p‑xylene over ZSM-5

  • 期刊论文

  • 发表日期：

    2026年7月30日

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  • Bing Yan,
  • Bohui Lu,
  • Xinshuai Li,
  • Guangming Min,
  • Xu Chen,
  • Kun Lu,
  • Zonghui Liu,
  • Bing Xue

摘要

The alkylation of toluene to p-xylene (PX) was considered a very promising route for synthesizing PX, owing to advantages such as high selectivity and low cost. Modified ZSM-5 zeolites were widely used catalysts, and achieving controlled modification drove significant research efforts. This work employed co-modification of ZSM-5 with B2O3 and MgO, where MgO deposition was designed to exploit both the formation of bulky Mg2+-citrate chelates and electrostatic interactions between these anionic chelates and electron-deficient boron sites in surface B2O3, aiming to preferentially anchor Mg species at external zeolite surfaces. This approach achieved simultaneous acidity regulation and selective elimination of external acid sites while suppressing MgO-induced pore blocking, consequently yielding catalysts with high alkylation activity and PX selectivity. At loadings of 3% B2O3 and 5% MgO, the catalyst delivered optimal performance with 13% toluene conversion and 80% PX selectivity at 400 °C.