Microporous Humins Synthesized in Concentrated Sulfuric Acid Using 5-Hydroxymethyl Furfural

Abstract

A new class of highly porous organic sorbents called microporous humins is presented. These microporous humins are derived from sustainable and industrially abundant resources, have high heat of CO 2 sorption, and could potentially be useful for the separation of carbon dioxide from gas mixtures. Their synthesis involves the polymerization of 5-hydroxymethyl furfural (HMF) in concentrated sulfuric acid and treatment with diethyl ether and heat. In particular, the porosities were tuned by the heat treatment. HMF is a potential platform chemical from biorefineries and a common intermediate in carbohydrate chemistry. A high uptake of CO 2 (up to 5.27 mmol/g at 0 °C and 1 bar) and high CO 2 -over-N 2 and CO 2 -over-CH 4 selectivities were observed. The microporous humins were aromatic and structurally amorphous, which was shown in a multipronged approach using 13 C nuclear magnetic resonance and Fourier transform infrared spectroscopies, elemental analysis, and wide-angle X-ray scattering.

Selective Adsorption of CO2 on Zeolites NaK-ZK-4 with Si/Al of 1.8–2.8

“…Commonly used ideal adsorbed solution theory (IAST) has complications for zeolites and gas pairs with significantly different adsorption affinities, such as CO 2 and N 2 . In addition, it is seldom recognized that the IAST model is not physically self-consistent when for adsorbents with negligible N 2 adsorption as the N 2 adsorption has to be estimated for unphysical high pressures . The Henry’s law model used in this study (the CO 2 -over-N 2 selectivity listed in Table ) is more robust than IAST but has obvious limitations in the pressure range, and the results should be treated with care when being extrapolated to the pressures relevant for real adsorption separation processes.…”

“… 39 In addition, it is seldom recognized that the IAST model is not physically self-consistent when for adsorbents with negligible N 2 adsorption as the N 2 adsorption has to be estimated for unphysical high pressures. 40 The Henry’s law model used in this study (the CO 2 -over-N 2 selectivity listed in Table 1 ) is more robust than IAST but has obvious limitations in the pressure range, and the results should be treated with care when being extrapolated to the pressures relevant for real adsorption separation processes. The highest CO 2 selectivity was observed for zeolite NaK-ZK-4 with an intermediate number of K + cations, irrespectively to the Si/Al ratio.…”

Humins from Biorefineries as Thermoreactive Macromolecular Systems

“…Valorization toward materials applications has been suggested, and it was demonstrated that humins improve the mechanical properties of thermosetting composites. Recently, other products, such as humins‐derived porous materials and active carbon, have also emerged, with possible applications such as sorbents and electrode materials. Several humins treatment processes have also been proposed, such as hydrotreatment, oxidation, and pyrolysis .…”

Microporous Humins Prepared from Sugars and Bio-Based Polymers in Concentrated Sulfuric Acid

“…or polymer, no clear pattern was revealed. The sulfur content was higher than for other microporous humins synthesized under similar conditions 59 and was likely introduced through the use of concentrated H 2 SO 4 . However, no sulfur content was detected for MHC.…”

“…58 Very recently, we showed that aerosols of liquid HMF that reacted with H 2 SO 4 could form microporous solids called microporous humins after a subsequent washing step with diethyl ether. 59 As HMF is a quite valuable product, we present another method here that can be used to derive microporous humins by reacting less valuable and more readily available sugars and bio-based polymers using a similar procedure.…”