Direct microwave energy input on a single cation for outstanding selective catalysis

Abstract

Microwave (MW)–driven catalytic systems are attracting attention not only as an aggressive electrification strategy of the chemical industry but also as creating a unique catalytic reaction field that conventional equilibrium heating cannot achieve. This study unlocked direct and selective heating of single alkali metal cations in the pores of aluminosilicate zeolites under MW. Selectively heated Cs + cations in FAU zeolite exhibited selective CH 4 combustion performance, that is, CO x generation at the heated Cs + cations selectively occurred while side reactions in the low-temperature gas phase were suppressed. The Cs-O pair distribution function revealed by synchrotron-based in situ x-ray total scattering gave us direct evidence of peculiar displacement induced by MW, which was consistent with the results of molecular dynamics simulation mimicking MW heating. The concept of selective monoatomic heating by MW is expected to open a next stage in “microwave catalysis” science by providing physicochemical insights into “microwave effects.”

Microwave Catalytic Co-Upcycling of Polyethylene and Polystyrene

“…HZSM-5 also facilitated BTX production using its 10-membering rings forming a channel that was highly size and shape selective to BTX. , As a result, sufficient heating at these channels can be beneficial towards BTX formation. In another instance, it was found that, under the influence of electromagnetic waves, the metal cation within the ZSM-5 framework exhibited vibrations which led to a temperature gradient within the catalyst channel . Several other works described yields equivalent to higher temperatures in the presence of MW-induced heating in a catalyst. , In our case, whilst plastic was found to be transparent to MW, the only available source of MW energy dissipation was the HZSM-5 channel.…”

“…In another instance, it was found that, under the influence of electromagnetic waves, the metal cation within the ZSM-5 framework exhibited vibrations which led to a temperature gradient within the catalyst channel. 43 Several other works described yields equivalent to higher temperatures in the presence of MW-induced heating in a catalyst. 44,45 In our case, whilst plastic was found to be transparent to MW, the only available source of MW energy dissipation was the HZSM-5 channel.…”

Simultaneous Control of Aluminum Atoms and Defects in the MOR Zeolite Framework by Postsynthetic Treatments

“…Zeolites, a group of crystalline aluminosilicates with microporous structures, are extensively used in various fields as catalysts, adsorbents, and ion exchangers. , Over 250 different zeolite framework structures with various pore sizes, cavities, and channel dimensionalities exist, and these differences significantly influence their performance in various applications. Additionally, factors such as the crystal size and morphology, the type of extra-framework cations, and the state of the crystal surfaces are crucial in determining the performance of zeolites.…”

“…All peaks were observed in the chemical shift range corresponding to Q 4 (Si(−O−Si) 4 ). The peak of Q 4 species was split into four peaks corresponding to T4, T2, T3, and T1, arranged from the high-field to the low-field side. 85 The broadened peak observed around −102 ppm (see Figure S5 for an enlarged graph) was assigned to an overlap of Si sites neighboring Al (Q 4 (1Al)) and ones connected to defective silanol (Q 3 ).…”

Dealumination of RHO zeolite by acid treatment and recrystallization with organic pore filler

“…1) The anionic charge of zeolite framework caused by the substitution of Si with Al is balanced by various cations, which works as active sites in various chemical reactions. 2) Small-pore zeolites, such as CHA, AEI, KFI, and RHO zeolites, are a group of zeolites that is characterized by their 8-rings (8R) as their largest pores. 3),4) These zeolites are gaining much attention due to their remarkable catalytic behavior.…”