In this work, the hierarchical pore HZSM-5 zeolite was synthesized by the method of alkali treatment, and the bimetallic loading of Mo and Cu was investigated for the hydrothermal aromatization of stearic acid. After alkali treatment, the pore size of HZSM-5 increased, but the acid sites decreased. The metal loading reintroduced the Lewis acid sites, greatly increasing the ratio to Brönsted acid sites. Therefore, the treated catalyst achieved higher hydrothermal stability while maintaining the high activity of hydrothermal aromatization of stearic acid. Mo0.02Cu0.01/Z-0.2M achieved excellent activity in the stearic acid hydrothermal aromatization with a high overall TEX (toluene, ethylbenzene, and xylenes) yield of 50.19 wt %, including 10.30 wt % toluene, 3.82 wt % ethylbenzene, and 36.07 wt % xylene. In addition, Mo0.02Cu0.01/Z-0.2M still showed excellent catalytic activity while applied in the system of the simulated microalgal bio-oil. As the reactant changed to the mixture of stearic acid and hexadecanamide, an overall TEX yield of 34.11 wt % was obtained at 450 °C. These results demonstrate the excellent hydrothermal aromatization ability of the MoCu-supported hierarchical pore ZSM-5 zeolite, which provides the potential to produce value-added chemicals from algal biomass.
Jingce Bi,Qingfeng Zhan,Yujing Chen,Zhiqiang Liang,Ningning Liu,Xia Zhang,Zhuopeng Wang,Yide Han
At present, the construction of hierarchically porous ZSM-5 molecular sieves using only cetyltrimethylammonium bromide (CTAB) as the template represents a major challenge in the field of molecular sieve synthesis. In this work, hierarchically porous ZSM-5 zeolite was synthesized via a straightforward conventional static hydrothermal method, employing CTAB as the sole template agent derived from CTAB-encapsulated silica sphere precursors. By controlling the dissolution rate of silica spheres, the release rate of CTAB is regulated, enabling the synthesis of pure-phase hierarchical porous ZSM-5 zeolite. The influences of alkalinity, aging time, Si/Al ratio, CTAB content and addition method, and crystallization time on the construction of hierarchically porous ZSM-5 molecular sieves were examined. The experimental results indicate that the crystallization process in this system proceeds in the order: MFI → MFI + kenyaite → MFI + quartz. Additionally, by managing the crystallization process, we systematically examined the formation process of impurities and established the optimal conditions for synthesizing pure-phase hierarchically porous ZSM-5 molecular sieves in this system. Moreover, the as-prepared hierarchically porous ZSM-5 molecular sieves demonstrated enhanced selectivity towards light olefins in the MTP reaction.
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