Tailoring Multiple Porosities of Hierarchical ZSM‐5 Zeolites by Carbon Dots for High‐Performance Catalytic Transformation

Abstract

A simple and high‐efficiency method is proposed to synthesize hierarchical ZSM‐5 zeolites with micropore and multistage mesopores by adopting water‐soluble carbon dots (CDots) with various size distributions, such as 1‐stage size distribution of CDots‐1 of around 23 nm, 2‐stage size distribution of CDots‐2 of 6 and 9 nm, 3‐stage size distribution of CDots‐3 of 5, 8, and 18 nm. The abundant OH and COOH groups on the surface of CDots provide high solubility in water. The characterization techniques confirmed that the dual‐porous h‐ZSM‐5 (MIcro–mEsopores) and multi‐porous h‐ZSM‐5 (MIcro–mEso–mEsopores), h‐ZSM‐5 (MIcro–mEso–mEso–mEsopores, M‐IEEE) catalysts are obtained. Notably, the hierarchical ZSM‐5(M‐IEEE) catalyst with micropore of 0.55 nm, two small mesopores of 4.8 and 7.4 nm, and one large mesopore of 17.5 nm show excellent catalytic performance with the highest 1,3,5‐triisopropylbenzene (TIPB) cracking conversion (97.3%) and high stability. Similarly, the h‐ZSM‐5(M‐IEEE) shows the high ethanol to olefins conversion (100%). The improved catalytic activity can be attributed to the more efficient diffusion of reactants and products in the crystals with the help of multistage mesopores, improved anti‐coking stability, combined with the effect of suitable acidity, and the increased accessibility of the acid sites.

Synergy of Extraframework Al3+ Cations and Brønsted Acid Sites on Hierarchical ZSM-5 Zeolites for Butanol-to-Olefin Conversion

“…The h-ZSM-5 (50) and Al/h-ZSM-5 (50) zeolites have a hysteresis loop that can provide evidence for additional mesoporous structure. 20,35,36 The pore size distributions of h-ZSM-5 (50) and Al/h-ZSM-5 (50) zeolites have been further analyzed by using BJH methods. As presented in Figure S2b, both the h-ZSM-5 (50) and Al/h-ZSM-5 (50) zeolites have an average mesopore size of around 4−6 nm.…”

“…The nitrogen adsorption–desorption isotherms of as-prepared hierarchical h-ZSM-5(50) zeolites with SiO 2 /Al 2 O 3 of 50 and Al 3+ -exchange Al/h-ZSM-5­(50) zeolites are shown in Figure S2a. The h-ZSM-5(50) and Al/h-ZSM-5(50) zeolites have a hysteresis loop that can provide evidence for additional mesoporous structure. ,, The pore size distributions of h-ZSM-5(50) and Al/h-ZSM-5(50) zeolites have been further analyzed by using BJH methods. As presented in Figure S2b, both the h-ZSM-5(50) and Al/h-ZSM-5(50) zeolites have an average mesopore size of around 4–6 nm.…”

“…N 2 adsorption−desorption isotherms measurements were performed at 77 K on an Autosorb IQ-C system after outgassing the sample under vacuum at 573 K for 10 h. The specific surface area was calculated with the Brunauer−Emmett−Teller (BET) equation. 35,36 The 27 Al and 31 P MAS NMR spectra were recorded by using a Bruker Avance III 400WB spectrometer at room temperature operated at a B 0 field of 9.4 T with Larmor frequencies of 104.3 and 161.9 MHz, respectively. A sample spinning rate of 12 kHz with 4 mm rotors was used for all experiments.…”

“…It was collected with a PANalytical XPert Pro powder diffractometer using Cu Kα radiation (λ = 1.5405 Å, 45 kV, and 40 mA). N 2 adsorption–desorption isotherms measurements were performed at 77 K on an Autosorb IQ-C system after outgassing the sample under vacuum at 573 K for 10 h. The specific surface area was calculated with the Brunauer–Emmett–Teller (BET) equation. , …”

Viscoelastic polyacrylate with hierarchical hollow zeolite for sound insulation

“…Microporous Zeolite Socony Mobil #5 are a class of microporous aluminosilicate compounds which have been used extensively as catalysts and adsorbents in the chemical industry. [23][24][25][26][27][28] Postprocessing to obtain hierarchical pores of ZSM-5 has been widely used. 29,30 In particular, alkali etching provides a hollow structure of ZSM-5.…”