Synthesis of hierarchical ZSM-5 zeolites with CTAB-containing seed silicalite-1 and its catalytic performance in methanol to propylene

Synthesis of an excellent MTP catalyst: hierarchical ZSM-5 zeolites with great mesoporosity

“…And although the total coke amount of SMZ-3 reached 23.8 wt%, the average coking rate was only 1.32, which was the minimum as calculated in figure 11 f . The reaction times of the samples of TMZ-2 and TMZ-3 were 127 h and 135 h, which were significantly longer than the results in the reported works [54,55] but shorter than that of SMZ-3; and the selectivity of propylene was 36.63% and 40.63%, respectively, further indicating that the hierarchical ZSM-5 zeolites synthesized either in silica sol or TEOS had great catalytic performance in the MTP reaction. Therefore, in comparison to the high average coking rate of sample CZ, the hierarchical zeolites exhibited much lower rates from 1.32 to 1.44, benefiting from the outstanding mesoporosity.…”

“…40 nm) was not detected in the DFT pore size distribution in figure 1 b . This high ‘aggregation’ morphology with micro–meso–macropores was conducive to the reactants' assessing the active acid sites effectively [54] and could improve the catalytic performance of the MTP process [55]. The clear lattice fringes in (F) have also been assumed to imply the microporous zeolite structure of SMZ samples.…”

“…The peak located around the low-temperature region could be ascribed to the interaction between the hydrogen bond and silicon-oxygen bond, and the peak around the high-temperature position was relevant to the framework aluminium [61,62]. Although these samples had the same SiO 2 /Al 2 O 3 molar ratios (SiO 2 /Al 2 O 3 = 200) as CZ, the nanosized primary crystals of the SMZ and TMZ samples caused a slight decrease in the amounts of the weak or strong acid sites [54]. And as to the strong acid sites, the SMZ samples showed lower amounts than the TMZ samples, which might be ascribed to the smaller nanocrystals domains of SMZ, indicating that the nanosized extent of hierarchical samples had a direct impact on the strong acid sites.…”

Synthesis and Characterization of Hierarchical ZSM-5 Zeolites with Outstanding Mesoporosity and Excellent Catalytic Properties

“…The optimal amount of ST is 3.1 g of the sample of MZ-3 in this work, and the continuing increase of ST can cause the decrease of S ext on the contrary. The optimal value of S ext in MZ-3 reaches to 300 m 2 /g, much higher than those of almost the ever reported works in synthesizing hierarchical ZSM-5 zeolites employing different mesoporogens and methods [ 26 , 27 , 30 , 36 – 38 ]. What is the most important is that the S mic of MZ-3 can still maintain at a very high level to 316 m 2 /g, slightly lower than that of 330 m 2 /g of TZ.…”

“…Sergio Fernandez et al have synthesized hierarchical beta zeolites with rational selection of pore-directing agents, and a top-down base leaching method has been demonstrated by the feasibility of tailoring the mesopore structures [ 26 ]. Hengbao Chen et al produced hierarchical ZSM-5 zeolites with cetyltrimethylammonium bromide (CTAB) containing silicalite-1 as seed, and the methanol to propylene (MTP) reaction was employed to investigate the catalytic performance of the as-obtained zeolite samples, which exhibited a comparable activity with the samples reported in literature [ 27 ]. Saros Salakhum et al have greenly synthesized hierarchical faujasite nanosheets from renewable resources of corn cob ash-derived nanosilica and as efficient catalysts for hydrogenation of lignin-derived alkylphenols, and the high yield of 4-propylcyclohexanol over this novel designed catalysts was about 2.14 times compared with the conventional faujasite [ 28 ].…”