One‐Pot Selective Synthesis of Renewable p‐Xylene by Completely Biomass‐Based Ethanol and Dimethylfuran with Functionalized Mesoporous MCM‐41

Abstract

One‐pot direct synthesis of renewable p‐xylene (PX) via Diels‐Alder cycloaddition of completely bio‐based ethanol and 2,5‐dimethylfuran (DMF) was studied comparatively over dealuminated HBeta zeolite and functionalized mesoporous MCM‐41. The sulfonic group‐functionalized MCM‐41 had better catalytic performances. Under the optimized conditions, an ethanol conversion of ∼100 %, 2,5‐DMF conversion of 79 % and PX selectivity of 80 % were obtained over NH3‐Silylated‐MCM‐41‐10 %SO3H catalyst with 0.8 wt % N content, which is much better than HBeta zeolite catalyst. X‐ray diffraction (XRD), thermogravimetric analysis (TGA), 29Si cross‐polarization magic‐angle spinning (CP/MAS) NMR and infared (IR) characterizations showed that sulfonic and silylated groups have been successfully grafted onto MCM‐41. Quantitative 1H MAS NMR with d5‐pyridine adsorption unambiguously demonstrated that silylated MCM‐41‐SO3H with NH3 pre‐treatment has much higher amount and stronger strength of Brönsted acid than zeolite catalyst. This is the vital factor to catalyze the dehydration of ethanol to ethylene and speed up the Diels‐Alder cycloaddition reaction, ultimately increase PX selectivity and reduce much less soft‐coke deposit on MCM‐41‐SO3H (∼4 wt %) than on HBeta zeolite (∼12 wt %). This work demonstrates a simple and economical strategy to further improve the potential for the production of sustainable chemicals from complete biomass.

Sulfonic Acid-Functionalized Inorganic Materials as Efficient Catalysts in Various Applications: A Minireview

“…In addition to the changes in proportion between these peaks, when functionalized, a new set of peaks in the range {−45;−80} ppm appears giving evidence for the covalent incorporation of the functional groups. The peaks correspond to three different environments for the siloxanes groups: T 1 , T 2 , and T 3 assigned respectively to [T m = RSi(OSi) m (OMe) 3-m ] [11,13,[81][82][83][84][85]. Khrisna et al [86], for example, attribute the presence of more T 3 species in RSO 3 H-MCM-41 compared to RSO 3 H-SBA-15 to a higher number of Q 3 in the bare MCM-41 precursor indicating a more efficient condensation.…”

Enhancement of p-xylene selectivity in the reaction between 2,5-dimethylfuran and ethanol over an ammonium fluoride-modified ZSM-5 zeolite

“…For the reaction between 2,5-DMF and ethanol, acid features and pore size (accessibility of active sites) play a leading role in Diels–Alder cycloaddition and dehydration reactions. 39 Therefore, FZ5 zeolites may be a promising catalyst for the reaction. However, the catalytic performance and mechanism of HZSM-5 modified by NH 4 F on the conversion of biomass have not been systematically studied by now.…”