Excellent catalytic performance over hierarchical ZSM-48 zeolite: Cooperative effects of enhanced mesoporosity and highly-accessible acidity

Ultrafast Synthesis and Regulating Al Status of Mesoporous ZSM-48 Zeolite via a Pretreated-Seed-Solution-Assisted Strategy

“…For both HZ48-Al-pre and HZ48-Al-post samples, a predominant resonance signal in 27 Al MAS NMR spectra (Figure a) is shown at 52 ppm, indicating a high content of tetrahedral coordination framework aluminum (Al­(IV), FAl), while a broad response of extra-framework aluminum (Al­(VI), EFAl) appears at 0 ppm . The ratios of EFAl/Al total and FAl/Al total were calculated based on the intensity of resonance peaks, as listed in Table . The EFAl/Al total of HZ48-Al-post (22.7%) was higher than that of HZ48-Al-pre (12.6%).…”

“…The ratio of Si/Al while a broad response of extra-framework aluminum (Al(VI), EFAl) appears at 0 ppm. 31 The ratios of EFAl/Al total and FAl/ Al total were calculated based on the intensity of resonance peaks, 30 as listed in Table 2. The EFAl/Al total of HZ48-Al-post (22.7%) was higher than that of HZ48-Al-pre (12.6%).…”

“…ZSM-48 is a crystalline high-silica aluminosilicate zeolite with an *MRE framework consisting of one-dimensional (1D) 10-membered ring tubular channel with a 0.53 nm × 0.56 nm pore opening . Due to its unique channel structure and acid property, ZSM-48 zeolites are highly desirable supports in long alkane isomerization reactions, − catalytic cracking of light naphtha , and methanol to hydrocarbons (MTH). − In recent years, much efforts have been done for optimizing the synthesis parameters of the *MRE zeolite. , Among which, in the synthesis of ZSM-48 by seed-assisted strategy, the predecessors studied the influence of whether seeds were presented or not, and the effect of feeding amount on the synthesis, achieving a relatively short synthesis time about 24 h . However, the correspondence between the crystallization of ZSM-48, property of ZSM-48 and the pretreated seed solution remains unraveled, in particular, variation of the treatment parameters.…”

Construction of Submicron Spherical ZSM-48 Zeolite: Crystallization Mechanism and Catalytic Application

“…As a porous material with a regular pore network, zeolites have been widely used in petrochemical and fine chemicals, − especially in the fields of catalysis − and separation. , The successful application of zeolite lies in its excellent molecular sieving capacity and tailorable acid properties. However, the mass-transfer problem caused by narrow micropores, especially for one-dimensional zeolite, has always been an unavoidable defect restricting its application. − Shortening the diffusion path of molecules in zeolite micropores is the key to partially circumventing its mass-transfer limitation, , which can be realized through post-treatment and direct synthesis strategies. However, the former usually results in low crystallinity and uncontrollable T-atom leaching, , and the latter mostly needs the assistance of organic growth regulators or complex preparation procedures. , Low-temperature crystallization is an alternative route to effectively reduce the size of zeolite without any organic additives. ,, While higher time consumption and more crystal defects are inevitable when low temperature is adopted, F – ions are the most frequent alternative OH – ions mineralizer in the synthesis of zeolite and allow zeolite to crystallize in a nearly neutral or even acidic environment. − In addition, the introduction of F – ions is more conducive to the growth of all silicon and perfect crystals. , Therefore, in this work, ammonium fluoride (NH 4 F) was introduced and cooperated with low-temperature crystallization to synthesize ZSM-48 zeolite with smaller size and fewer defects.…”

Construction of a One-Dimensional Al-Rich ZSM-48 Zeolite with a Hollow Structure

“…Zeolites are crystalline materials with well-defined micropores and tailorable acidity, and they have been applied in a wide range of catalytic processes and other industrial processes. − As an important branch of zeolite materials, one-dimensional (1D) zeolites exhibit specific applications in the fields of isomerization. − Generally, 1D zeolites are easy to grow into rods or needles along the main channel direction, leading to severe diffusion limitation. − Moreover, such morphologies are harmful to human health as they easily penetrate into the respiratory system . Hence, changing the growth trend of 1D zeolites and overcoming the problem of limited diffusion on the premise of good shape selectivity are of great importance.…”