Impact of Porous Silica Nanosphere Architectures on the Catalytic Performance of Supported Sulphonic Acid Sites for Fructose Dehydration to 5-Hydroxymethylfurfural

5-hydroxymethylfurfural represents a key chemical in the drive towards a sustainable circular economy within the chemical industry. The final step in 5-hydroxymethylfurfural production is the acid catalysed dehydration of fructose, for which supported organoacids are excellent potential catalyst candidates. Here we report a range of solid acid catalysis based on sulphonic acid grafted onto different porous silica nanosphere architectures, as confirmed by TEM, N2 porosimetry, XPS and ATR-IR. All four catalysts display enhanced active site normalised activity and productivity, relative to alternative silica supported equivalent systems in the literature, with in-pore diffusion of both substrate and product key to both performance and humin formation pathway. An increase in-pore diffusion coefficient of 5-hydroxymethylfurfural within wormlike and stellate structures results in optimal productivity. In contrast, poor diffusion within a raspberry-like morphology decreases rates of 5-hydroxymethylfurfural production and increases its consumption within humin formation.

High-Performance Heterogeneous Thermocatalysis Caused by Catalyst Wettability Regulation

Catalyst wettability regulation has emerged as an attractive approach for high catalytic performance for the past few years. By introducing appropriate wettability, the molecule diffusion of reactants and products can be enhanced, leading to high activity. Besides this, undesired molecules are isolated for high selectivity of target products and long-term stability of catalyst. Herein, we summarize wettability-induced high-performance heterogeneous thermocatalysis in recent years, including hydrophilicity, hydrophobicity, hybrid hydrophilicity-hydrophobicity, amphiphilicity, and superaerophilicity. Relevant reactions are further classified and described according to the reason for the performance improvement. It should be pointed out that studies of utilizing superaerophilicity to improve heterogeneous thermocatalytic performance have been included for the first time, so this is a comparatively comprehensive review in this field as yet.

Biomass-derived chemical substitutes for bisphenol A: recent advancements in catalytic synthesis

Bisphenol A is an oil-derived, large market volume chemical with a wide spectrum of applications in plastics, adhesives and thermal papers. However, bisphenol A is not considered safe due to its endocrine disrupting properties and reproductive toxicity. Several functional substitutes of bisphenol A have been proposed in the literature, produced from plant biomass. Unless otherwise specified, the present review covers the most significant contributions that appeared in the time span January 2015-August 2019, describing the sustainable catalytic synthesis of rigid diols from biomass derivatives. The focus is thereupon on heterogeneous catalysis, use of green solvents and mild conditions, cascade processes in one-pot, and continuous flow setups. More than 500 up-to-date references describe the various substitutes proposed and the catalytic methods for their manufacture, broken down according to the main biomass types from which they originate.

A method for simultaneously crosslinking and functionalizing extracellular matrix-based biomaterials as bioprosthetic heart valves with enhanced endothelialization and reduced inflammation

With the coming of an aging society and the emergence of transcatheter valve technology, the implantation of bioprosthetic heart valves (BHVs) in patients with valvular disease has significantly increased worldwide. Currently, most clinically available BHVs are crosslinked with glutaraldehyde (GLUT). However, the GLUT treated BHV is less durable due to the combined effect of multiple factors such as cytotoxicity, immune responses, and calcification. In this study, the in-situ polymerization of sulfonic monomers with a decellularized extracellular matrix (ECM) was performed to simultaneously achieve the crosslinking and functionalization of ECM. Subsequently, the feasibility of the hybrid ECM used as leaflet material of BHV was evaluated. In in-vitro tests, the results indicated that the hybrid ECM fixed collagen efficiently and the introduction of sulfonic polymer promoted the proliferation and migration of human umbilical vein endothelial cells (HUVECs). In in-vivo tests, after being implanted in SD rats and mice, the hybrid ECM significantly inhibited immune response and calcification compared with the non-hybrid counterpart and GLUT crosslinked tissue. These results indicated that the hybrid ECM exhibited more competitive stability and better biocompatibility compared to these features in GLUT-crosslinked valve. Therefore, the sulfonic polymer hybrid ECM provides a potential material for more durable BHV and the in-situ polymerization strategy can serve as a general treatment method for tissue crosslinking as well as tailoring the biophysical properties of ECM.

Efficient Synthesis of Structured Phospholipids Containing Short-Chain Fatty Acids over a Sulfonated Zn-SBA-15 Catalyst

Catalytic production of structured phospholipids (SPLs) containing short-chain fatty acids (SCFAs) in an efficient heterogeneous manner is of great importance from the standpoint of food engineering. Herein, a bifunctionalized sulfonated Zn-SBA-15 catalyst was studied for SPL synthesis through interesterification of soybean lecithin with ethyl propionate or methyl butyrate. Various characterization techniques such as pyridine Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy were conducted to determine the physicochemical properties, so as to build the possible structure-reactivity relationship of the catalyst. In screening tests with commercial Amberlyst-15 or other SBA-15-type materials, the as-prepared sample showed promising catalytic performance probably owing to its mesoporous structure and cooperative role of Brönsted and Lewis acid sites. Notably, the sample was easily separated and recycled without obvious deactivation. In general, the investigated catalyst was regarded as one of the promising alternatives to otherwise expensive biocatalysts for SCFA-containing SPL production.

Aqueous Room Temperature Mono-Dehydration of Sugar Alcohols Using Functionalized Yttrium Oxide Nanocatalysts

The aqueous room temperature mono-dehydration of sugar alcohols (D-sorbitol and D-mannitol) was conducted using functionalized yttrium oxide nanocatalysts prepared via sol-gel methods. Materials exhibited high selectivity to mono-dehydration products. Solvent and catalyst effects were also investigated and discussed. The introduction of titanium into the yttrium oxide framework would decrease both substrate conversion and mono-dehydration efficiency. In addition, studies of the catalytic mechanism indicate high mono-dehydration efficiency may come from the stability of the formed intermediate during catalysis. This work provides a highly efficient and benign system for catalytic mono-dehydration of sugar alcohols.

Direct conversion of cellulose into isosorbide over Ni doped NbOPO4 catalysts in water

Ni doped NbOPO₄ catalysts were used efficiently for the one-pot conversion of cellulose to isosorbide under aqueous conditions.

Solvent-Free Production of Isosorbide from Sorbitol Catalyzed by a Polymeric Solid Acid

A series of polymeric solid acid catalysts (PDSF-x) is prepared by grafting strong electron-withdrawing groups (-SO₂ CF₃ ) on a sulfonic acid-modified polydivinylbenzene (PDS) precursor synthesized hydrothermally. The effect of acid strength on sorbitol dehydration is investigated. The textural properties, acidity, and hydrophobicity are characterized by using Brunauer-Emmett-Teller analysis, elemental analysis, and contact angle tests. The results of FTIR spectroscopy and X-ray photoelectron spectroscopy show that both -SO₃ H and -SO₂ CF₃ are grafted onto the polymer network. We used solid-state ³¹ P NMR spectroscopy to show that the acid strength of PDSF-x is enhanced significantly compared with that of PDS, especially for PDSF-0.05. As a result, PDSF-0.05 exhibits the highest isosorbide yield up to 80 %, a good turnover frequency of 231.5 h^-1 (compared to other catalysts), and excellent cyclic stability, which is attributed to its large specific surface area, appropriate acid strength, hydrophobicity, and stable framework structure. In addition, a plausible reaction pathway and kinetic analysis are proposed.

Versatile design and synthesis of mesoporous sulfonic acid catalysts

Mesoporous sulfonic acid catalysts (MSAC) are widely used in acid-catalyzed reactions, including biomass conversions with plenty of polar solvents and precursors. The catalytic efficiency of MSAC is greatly affected by the microenvironment around the sulfonic acid sites. In this review, the progress on modification of microenvironment of MSAC is reviewed over the past decade. Hydrophobic modification allows MSAC prevent the adhesion of water molecules onto sulfonic acid sites, to abate the risk of reduced acid strength and catalytic efficiency. In comparison, hydrophilic properties can bring positive effect on acid-catalyzed reactions with the aid of hydrophilic interaction between polar functional groups on MSAC and hydrophilic groups of specific substrates. Amphiphilic MSAC with tunable wettability for specific substrates and solvents tend to improve the efficiency in certain reactions with mixed solvents or reactants of different polarity, especially for biphasic systems of immiscible liquids. Furthermore, much attention has been attracted on modification of surface to simulate the microenvironment of homogeneous solvents and enzyme biocatalysts in recent research. New trends of this field are also highlighted.

Isosorbide and dimethyl carbonate: a green match

In this review the reactivity of the bio-based platform compounds D-sorbitol and isosorbide with green reagents and solvent dimethyl carbonate (DMC) is reported. Dehydration of D-sorbitol via DMC in the presence of catalytic amounts of base is an efficient and viable process for the preparation of the industrially relevant anhydro sugar isosorbide. This procedure is "chlorine-free", one-pot, environmental friendly and high yielding. The reactivity of isosorbide with DMC is equally interesting as it can lead to the formation of dicarboxymethyl isosorbide, a potential monomer for isosorbide-based polycarbonate, and dimethyl isosorbide, a high boiling green solvent. The peculiar reactivity of isosorbide and the non-toxic properties of DMC represent indeed a green match leading to several industrial appealing potential applications.

Sorbitol dehydration into isosorbide over a cellulose-derived solid acid catalyst

The dehydration of sorbitol to isosorbide over an environmentally benign cellulose-derived solid acid catalyst (CCS) has been investigated in order to develop a sustainable process for isosorbide production.