Excellent Performances of Dealuminated H‐Beta Zeolites from Organotemplate‐Free Synthesis in Conversion of Biomass‐derived 2,5‐Dimethylfuran to Renewable p‐Xylene

Abstract

Direct synthesis of renewable p-xylene (PX) by cycloaddition of biomass-derived 2,5-dimethylfuran (2,5-DMF) and ethylene was achieved over Al-rich H-beta zeolites synthesized by an organotemplate-free approach and their dealuminated counterparts with different Si/Al ratios. Among them, H-beta zeolite with an Si/Al ratio of 22, obtained from an Al-rich parent by dealumination, was found to be an excellent catalyst for the synthesis of PX. A PX yield of 97 % and 2,5-DMF conversion of 99 % were obtained under optimized conditions. These results are even better than those of a commercial H-beta zeolite prepared using a organotemplate synthesis with a similar Si/Al ratio of 19. The excellent performance of the H-beta zeolite with Si/Al ratio of 22 is closely related to its acidity and porous structure. A moderate Brønsted/Lewis acid ratio can improve the conversion of 2,5-DMF to as high as 99 %. Furthermore, dealuminated H-beta zeolite has a secondary pore system that facilitates product diffusion, which increases the selectivity to PX. In addition, this catalyst shows better regeneration. After five successive regeneration cycles, the yield of PX was still as high as 85 % without obvious dealumination. This work provides a deeper understanding of the more general Diels-Alder cycloaddition of furan-based feedstocks and olefins and significantly improves the potential for the synthesis of chemicals from lignocellulosic biomass.

Production of aromatics from biomass by computer-aided selection of the zeolite catalyst

“…BEA and FAU zeolites have both been described in the literature as the active catalysts for selectively achieving p-xylene from biomass-derived furanes. 4,[13][14][15][16] Thus, the stabilization of the reaction intermediate, oxanorbornene, has been explored at different positions within the FAU and BEA structures, and the best geometrical fitting has been obtained in the middle of the supercavity in the case of FAU (see Fig. 2b) and at the channel intersection in the BEA structure (see Fig.…”

“…9,10 When the recent literature is reviewed, the preferred catalysts reported for the selective transformation of DMF to p-xylene are large-pore zeolites, in particular FAU 4,11,12 and Beta-type zeolites. [13][14][15][16][17] According to different experimental and computational studies, it has been established that the limiting step of the overall reaction is the non-catalyzed DA cycloaddition. 4,17,18 Thus, the ability to design zeolite-based catalysts that allow promotion of the DA reaction should have a direct influence on improving the overall reaction rates.…”

Efficient manganese decorated cobalt based catalysts for hydrogenation of 5‐hydroxymethylfurfural (HMF) to 2,5‐dimethylfuran (DMF) biofuel

“…Moreover, DMF has the potential to be an alternative fuel, and the use of DMF in vehicles with gasoline does not require any changes in the vehicle engine . Besides the possible use of DMF as an alternative fuel or fuel additive, DMF can also be converted to valuable chemicals such as p‐xylene through Diels‐Alder reactions …”

“…[9,10] Besides the possible use of DMF as an alternative fuel or fuel additive, DMF can also be converted to valuable chemicals such as pxylene through Diels-Alder reactions. [11][12][13] DMF is synthesized by the catalytic hydrogenation of HMF. As seen in Scheme 1, according to the possible mechanism, the synthesis of DMF takes place in two steps.…”

Fabrication of Pd3@Beta for catalytic combustion of VOCs by efficient Pd3 cluster and seed-directed hydrothermal syntheses

“…By contrast, supported noble-metal (e.g., palladium and platinum) catalysts display excellent catalytic activity and metal stability for VOCs combustion. Especially, zeolite-supported noble metal catalysts combined with the advantages of the zeolites (particular porous structure, large adsorption capacity and controllable acid sites) [1][2][3][4] and the noble metals (high low-temperature reactivity and stability) were extensively investigated for its selective adsorptive properties, low-temperature activity, hightemperature stability and accessible active sites. Wang et al found that Ru/hierarchical HZSM-5 catalyst could act as both adsorbent and catalyst for aromatic VOCs elimination under low concentration levels.…”