Direct 2,3-Butanediol Conversion to Butene-Rich C₃₊ Olefins over Copper-Modified 2D Pillared MFI: Consequence of Reduced Diffusion Length

Abstract

2,3-Butanediol (2,3-BDO), a critical C 4 platform chemical derived from biomass, syngas, or CO 2 , can be converted to C 3+ olefins, serving as important renewable feedstocks for producing sustainable aviation fuels to decarbonize the hard-toelectrify air transportation sector. Herein, we report a bifunctional Cu-modified diffusion-free 2D pillared MFI catalyst (Cu/PMFI) which can selectively catalyze 2,3-BDO conversion to butene-rich C 3+ olefins (95% selectivity at 97% conversion, 523 K). 2,3-BDO conversion to butenes over Cu/PMFI primarily occurs via methyl ethyl ketone intermediate while 2-methyl propanal is also observed as another minor dehydration product that leads to butene formation. In comparison with a control mesoporous Cu/ZSM-5 sample prepared by the postsynthetic approach, Cu/PMFI shows favorable C 3+ olefin selectivity (95% over Cu/PMFI vs 80% over Cu/ZSM-5 at ∼5.1 h TOS). The coke formation over Cu/PMFI is dramatically suppressed by >50% in contrast to Cu/ZSM-5 in 90 h 2,3-BDO conversion due to the reduced diffusion length. Cu/PMFI also favors butene formation and minimizes nonbutene C 3+ olefins by inhibiting the downstream oligomerization and cracking reactions. This study highlights the usefulness of the diffusion-free 2D PMFI materials in catalytic conversion of biomass-derived platform molecules and the significance of diffusion impact on catalyst coke formation and product distributions.

Two-Dimensional Zeolites–Potential Catalysts for Biomass Valorization

“…The conversion of 2,3-BDO involves hydrogenation and dehydration steps, and different products are possible as shown in Scheme . The cascade reactions involved were catalyzed by different Cu species and Lewis & Bronsted acidic sites present on the multifunctional Cu/PMFI zeolite …”

“…The mesoporous channels present in pillared MFI zeolites facilitate the diffusion of butenes from the micropores, thereby eliminating further oligomerization, hydrogenation, or cracking reactions that produce nonbutene olefins. The reduced diffusion length also limits the coke formation in the pores …”

“…The cascade reactions involved were catalyzed by different Cu species and Lewis & Bronsted acidic sites present on the multifunctional Cu/PMFI zeolite. 30 The reaction was performed in a hydrogen environment at 573 K and Cu/PMFI showed notable activity with 38% selectivity to butenes at >96% conversion, along with various other products like C 2 −C 4 alkanes, ethylene, propene, and methyl ethyl ketone. The mesoporous channels present in pillared MFI zeolites facilitate the diffusion of butenes from the micropores, thereby eliminating further oligomerization, hydrogenation, or cracking reactions that produce nonbutene olefins.…”

Sustainable Production of Emerging Diesel Additive from Butene by Palladium-Catalyzed Alkoxycarbonylation

“…On the other hand, butenes are one of the byproducts of the stream cracking of naphtha. − With the development of coal to olefin, as well as the petroleum refining and chemical integration process, the productivity of butenes has been greatly improved, which is approximately 132 million tons per year by 2017 and grows at approximately 4% annually . Besides, butenes can be produced from the catalytic pyrolysis of biomass. − In view of the potential of pentanoic esters fuel and the rich source of butenes, we herein proposed a direct and 100% atom-economic route to produce linear and branched pentanoic esters via one-step alkoxycarbonylation of 1-butene (route b, Figure ), under considerable mild reaction conditions (lower temperature and gas pressure) if compared with the route a. Carbonylation is an effective strategy for the preparation of oxygenated compounds and carbon chain growth. − Some active Pd/phosphine catalysts for alkoxycarbonylation of olefins has been developed using phosphines as the ligands, − however, these ligands are highly expensive; e.g., the price of the best 1,2-bis(di- t -butylphosphino)- o -xylene is $5600/25 g . Moreover, these alkyl phosphine ligands are highly sensitive to oxygen, which greatly increases the cost during the preparation and preservation processes and thus limits their application potential.…”

Recovery of 2,3-Butanediol from Fermentation Broth by Zeolitic Imidazolate Frameworks

“…Among such intermediates, 2,3-butanediol (2,3-BDO) has emerged as one of the most important. Its C 4 size confers advantages over C 1 and C 2 intermediates during catalytic conversion to liquid hydrocarbon mixtures, and it also has many other applications as a platform chemical. − The biological (fermentative) production of 2,3-BDO has made considerable progress with a particularly attractive route starting from lignocellulosic wastes (e.g., corn stover). , However, the high boiling point (180 °C), high affinity with water, and low concentration (∼10 wt %) in typical fermentation product broths create a significant challenge in 2,3-BDO separation from the complex fermentation broths that also contain residual sugars, fermentation byproducts, and biological macromolecules. This issue becomes a significant bottleneck for the development of economical processes for biofuel production via the 2,3-BDO route …”