Rapid Synthesis of Diesel Precursors from Biomass-Derived Furanics Over Aluminum-Doped Mesoporous Silica Sphere Catalysts

The condensation of biomass-derived molecules has been increasingly utilized as a sustainable strategy for the preparation of high-carbon precursors for high-density fuels, thus stimulating the demand for more efficient catalysts. This study concerns the synthesis of an aluminum-doped mesoporous silica sphere (Al-MSS) catalyst for the conversion of biobased furfural and 2-methylfuran into a C₁₅ diesel precursor through a hydroxyalkylation/alkylation (HAA) reaction. A series of Al-MSS catalysts with different Si/Al ratios and calcination temperatures is prepared and extensively characterized, among which Al-MSS20-450 (Si/Al=20 : 1, calcined at 450 °C) exhibits unprecedentedly high reaction efficiency in catalyzing HAA reaction, offering a 94 % product yield at 140 °C in 20 min. The catalyst also gives high product yields across a broad temperature range from 80 °C to 140 °C with varied reaction time. Reaction kinetics reveal that both competitive substrate adsorption and temperature-dependent system viscosity affect the reaction efficiencies. Correlations between the catalytic activity and surface acid sites disclose that moderate and strong acid sites are primarily responsible for catalysis. Brønsted and Lewis acid sites are found by poisoning assays to work synergistically to catalyze the reaction, with the former being the primary sites. Finally, the catalyst displays good recycling performance, which further highlights its potential for industrial application.

Synthesis of Hollow Mesoporous Silica Nanospheroids with O/W Emulsion and Al(III) Incorporation and Its Catalytic Activity for the Synthesis of 5-HMF from Carbohydrates

Controlling the particle size as well as porosity and shape of silica nanoparticles is always a big challenge while tuning their properties. Here, we designed a cost-effective, novel, green synthetic method for the preparation of perforated hollow mesoporous silica nanoparticles (PHMS-1) using a very minute amount of cationic surfactant in o/w-type (castor oil in water) emulsion at room temperature. The grafting of Al(III) through post-synthetic modification onto this silica framework (PHMS-2, Si/Al ~20 atomic percentage) makes this a very efficient solid acid catalyst for the conversion of monosaccharides to 5-HMF. Brunauer–Emmett–Teller (BET) surface area for the pure silica and Al-doped mesoporous silica nanoparticles (MSNs) were found to be 866 and 660 m2g−1, respectively. Powder XRD, BET and TEM images confirm the mesoporosity of these materials. Again, the perforated hollow morphology was investigated using scanning electron microscopic analysis. Al-doped hollow MSNs were tested for acid catalytic-biomass conversion reactions. Our results show that PHMS-2 has much higher catalytic efficiency than contemporary aluminosilicate frameworks (83.7% of 5-HMF yield in 25 min at 160 °C for fructose under microwave irradiation).

Sol–Gel Synthesis of Microporous Carbon Using Resorcinol and Formaldehyde

Microporous carbon materials were prepared by thermal decomposition of a xerogel. The xerogel was synthesised through polycondensation of resorcinol and formaldehyde using an acid-catalysed sol–gel method. Acetic acid (1 M) was used as a catalyst. The effect of the molar ratio of resorcinol/catalyst (10/3, 5, 10, 20) on the obtained hydrogel was studied. The temperature range 25–110 °C was used to convert the hydrogel into a solid resorcinol/formaldehyde xerogel. The optimum molar ratio of resorcinol/catalyst was found to be 10/3. The dried xerogels were pyrolysed under an argon atmosphere at 800 °C to obtain microporous carbon materials with a uniform structure consisting of hollow particles and a specific surface area of 650 m2 g−1.

Synthesis, decoration, and cellular effects of magnetic mesoporous silica nanoparticles

Synthesis of magnetic core@shell nanoparticles with different coatings and the study of their uptake by cells.