Yafei Li,Shiqing Wang,Shunxin Fan,Babar Ali,Xiaocheng Lan,Tiefeng Wang
For the ethanolysis of biomass-derived furfuryl alcohol (FA) to value-added ethyl levulinate (EL), the development of an efficient solid acid catalyst is very important for industrial application with high FA concentration. Herein, a H-ZSM-5 catalyst with nano b-axis channels (NB-H-ZSM-5) was synthesized and used for the conversion of FA. Detailed catalyst characterization proved that the NB-H-ZSM-5 catalysts (Si/Al = 25∼125) with ∼70 nm b-axis channels were successfully prepared. The NB-H-ZSM-5 catalyst with Si/Al = 75 showed the highest activity. Its structural characteristics allowed for fast diffusion of reactants and products and full utilization of active sites, which endowed it with higher activity compared to commercial H-ZSM-5 (C-H-ZSM-5). Its moderate acidity effectively inhibited the polymerization of FA even at a high FA concentration of 20 wt %. The spent catalyst was easily regenerated by coke burn-off to give a good recyclability. Furthermore, based on the proposed reaction network, a method of physically mixing the NB-H-ZSM-5 (75) catalyst with a small amount of Amberlyst-15 was proposed to further increase the EL yield from 64.7 to 82.1% at an FA concentration of 6 wt %.
The synthesis of zeolites from natural aluminosilicate minerals is environmentally sustainable. However, the preparation of nano-ZSM-5 zeolite single crystals via the facile “silica–alumina homologation” of natural clay remains challenging. This paper highlights a novel strategy for the synthesis of defect-free, highly crystalline nano-H-ZSM-5 with a uniform morphology through the kinetically controlled in situ reconstruction of the topology of natural clay within a solid-state-like system. Crystal nucleation and growth were decoupled by aging to control the crystal size. The “homogeneous silica–alumina” property of natural clay was found to be directly inherited by nano-H-ZSM-5 to provide uniformly distributed acidic sites for catalysis. This was demonstrated by methanol-to-propylene conversion, wherein the performance of the obtained crystals was superior to that of commercial ZSM-5. This strategy promotes the development of natural silica–aluminate clay resources and allows the scalable production of high-quality nano-H-ZSM-5 single crystals for heterogeneous catalysis .
Song Baodong,Li Yongqiang,Cao Gang,Sun Zhenhai,Han Xu
In the transformation of methanol to gasoline (MTG), the selectivity to gasoline and the aromatic content in the produced gasoline are important factors. The catalytic activities of steam-treated and non-steam-treated nano-scale H-ZSM-5 (NHZ5) catalysts impregnated with Ag(I), Zn(II) or P(V) have been investigated in a continuous flow fixed bed reactor. The NH 3 -TPD results showed that after impregnation, the Ag/NHZ5, Zn/NHZ5 and P/NHZ5 catalysts contained comparatively more strong, medium-strong and weak acid sites, respectively. Treatment with steam decreased the number of acid sites in all the catalysts, but the pore volumes in the catalysts were larger which improved carbon deposition resistance resulting in prolonged lifetimes. After 6 h of MTG reaction, the selectivity to gasoline for the steam-treated catalysts,
\(Ag_{H_2 O} /NHZ5\) , \(Zn_{H_2 O} /NHZ5\) and \(P_{H_2 O} /NHZ5\) were 70.5, 68.4 and 68.7 wt-%, respectively, whereas their respective aromatic contents in the produced gasoline were 61.9, 55.4 and 39.0 wt-%. Thus \(P_{H_2 O} /NHZ5\) is the most promising catalyst for MTG applications which can meet the China IV gasoline standard that the amount of aromatics in gasoline should be less than 48 wt-%.
危险品化学品经营许可证（带存储）