Quantitative production of butenes from biomass-derived γ-valerolactone catalysed by hetero-atomic MFI zeolite

Abstract

If citing, it is advised that you check and use the publisher's definitive version. General rights Copyright and moral rights for the publications made accessible in the Research Explorer are retained by the Efficient production of light olefins from renewable biomass is a vital and challenging target to achieve future sustainable chemical processes. Here we report a hetero-atomic MFI-type zeolite (NbAlS-1), over which aqueous solutions of γ-valerolactone (GVL), obtained from biomass-derived carbohydrates, can be quantitatively converted to butenes with a yield of >99% at ambient pressure under continuous flow conditions. NbAlS-1 incorporates simultaneously niobium(V) and aluminium(III) centres into the framework and thus has a desirable distribution of Lewis and Brønsted acid sites with optimal strength. Synchrotron X-ray diffraction and absorption spectroscopy show that there is cooperativity between Nb(V) and Brønsted acid sites on confined adsorption of GVL, while the catalytic mechanism for conversion of confined GVL to butenes is revealed by in situ inelastic neutron scattering, coupled with modelling. This study offers a prospect for the sustainable production of butene as a platform chemical for the manufacture of renewable materials. Approximately 400 million tonnes of light olefins (ethene, propene and butenes) are produced each year for polymer, chemical and pharmaceutical industries 1-6. State-of-the-art processes are based on stream cracking of naphtha and thus critically rely on fossil fuels, possessing significant environmental impacts 1. Catalytic production of light olefins from renewable plant biomass is a highly promising target 7 , and many processes have been developed to bridge future gaps in the supply of commodity chemicals from biomass 8-11. In particular, biomass-derived γ-valerolactone (GVL), obtained from agricultural waste via low-cost, high-yield commercial processes (production scale at 27 tonnes in 2018), has been identified as a sustainable resource to produce butenes 12 , which, through well-established petroleum processes, can be readily transformed to a wide spectrum of petrochemicals, such as propene 2,13 , 1,3-butadiene 14 , aromatics 15 , liquid fuels 2,9 , polyethylene 2,16 and polybutene 2,17. In this respect, development of efficient catalytic processes to convert GVL to butenes is of vital importance. This conversion involves the ring-opening and decarboxylation reactions catalysed over solid acids, and amorphous SiO2/Al2O3, ZSM-5, La/ZSM-5, Ni2P/MCM-41, Zn-AlPO-5 and Pd/Nb2O5 have been studied 9,15,18-24. Using a 30 wt% GVL feedstock at 375 ºC and atmospheric pressure, a butene yield of 75% has been achieved over the SiO2/Al2O3 catalyst 9. Commercial supplies of GVL from biorefineries are aqueous solutions with GVL concentrations between 20-40 wt% 15 ; however, the water in the reaction can partially or completely deactivate solid-acid catalysts by coordinating to the acid sites and forming acid-base adducts 25,26. Thus, the design of an efficient, yet water-tolerant ca...

PtZn intermetallic nanoalloy encapsulated in silicalite‐1 for propane dehydrogenation

“…To further prove that part of Zn atoms were incorporated into the framework of MFI zeolite, the vibrational modes of ZnOSi moieties in PtZn@S‐1 were detected by Fourier transform infrared (FTIR) spectroscopy (970 cm −1 , Figure S11). The results indicated the incorporation of Zn(II) centers were as the framework sites due to the p–d transition of 2p electron from skeleton oxygen to empty d band of heteroatom 56,57 . As shown in the Zn 2p XPS spectra (Figure S12), cationic Zn species in PtZn@S‐1 exhibited a higher binding energy of about 1022.9 eV compared with that of PtZn/S‐1 and K‐PtZn@S‐1.…”

Net Zero and Catalysis: How Neutrons Can Help

“…One compound of particular interest is butene, a key platform chemical. It was shown [84] that a Nb substituted ZSM-5 (Si:Al = 25, Si:Nb = 37) zeolite was capable of 80% selectivity to butene from GVL at 320 • C and 1 bar. This was only possible because the substituted zeolite had both Lewis and Brønsted sites that could chelate the GVL.…”

“…The work discussed here, shows that neutron scattering has an important part to play. Reproduced from [83] with permission of Elsevier (left) and from [84] with permission of Springer Nature (right).…”

“…Catalysts are required for both the anode and the cathode. There are three main types of fuel cell: (i) low Reproduced from [83] with permission of Elsevier (left) and from [84] with permission of Springer Nature (right).…”

Construction of C-C bonds via photoreductive coupling of ketones and aldehydes in the metal-organic-framework MFM-300(Cr)

“…More importantly, the micropore environment offers a unique platform to activate the substrates via confined adsorption arising from the specific host–guest interactions 18 – 20 . The impact of host–guest interactions on the activation of adsorbed substrates and catalytic activity in supramolecular cages 21 – 23 and zeolites 24 , 25 have been widely studied. In contrast, the impact on confined catalysis of host–guest structures in MOFs is less well defined 26 , 27 .…”