Mesoscopically structured ZSM-5 nanosheets were prepared as highly active catalysts for the alkylation between toluene with methanol. The results showed that the Brønsted acid sites of ZSM-5 nanosheets were mainly distributed on the external surface in aluminum-rich zeolites owing to the charge-balance between positive quaternary ammonium cation (N + ) in C ph-10-6-6 , Na + ions and negative aluminosilicate species. In addition, it revealed that high alkalinity was easier to depolymerize the Si O Si species in Aluminum-rich synthesis gel, and the high alkalinity was required for silica-rich systems to dissolve silica species in order to finish the selfassemble process, leading to ZSM-5 nanosheets with high alkalinity presenting enhanced catalytic performance. Moreover, the optimized ZSM-5-50-2.5 was effective for the alkylation between toluene and methanol with toluene conversion of up to 50%, and it was stably operated for 48 h under the harsh conditions of WHSV = 32.5 h À1 with a desired stability.
A dual-template strategy with poly(ethylene glycol) (PEG) and cetyltrimethylammonium bromide (CTAB) was employed to synthesize the β-zeolite nanocrystal aggregates with ultrafine and hierarchical structure (micropores combined with intra-mesopores and inter-mesopores), and the particle size of aggregates and the nanocrystal size of β-zeolites can be systematically tailored by tuning the molar ratios of CTAB/PEG. In the alkylation between benzene and cyclohexene, the β-zeolite nanocrystal aggregates synthesized in the presence of PEG exhibited outstanding activity and resistance to deactivation under harsh reaction conditions, and the lifetime of β-5C4P was extended by 4.3 times compared with the commercial nanosized βzeolite, indicating that the additional PEG played the role of crystal growth inhibitors to reduce the size of nanocrystals, which increased the amount of accessible external Brønsted acid sites and effectively enhanced the diffusion properties. The experimental data for the spent β-zeolites revealed that the deactivation of zeolites was attributed to the blocking of channels and the loss of active sites occurred due to the inevitable side reactions. In addition, the resultant β-zeolite nanocrystal aggregates also presented robust regeneration performance, which identified a facile and effective route to directly prepare β-zeolite nanocrystal aggregates with excellent catalytic properties in the alkylation of aromatics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.