Mesoporous Sulfonated Carbon Materials Prepared by Spray Pyrolysis

Abstract

A one‐step approach was developed for the production of mesoporous sulfonated carbon materials by means of an aerosol synthesis. Nebulizing a clear aqueous solution of sucrose and sulfuric acid through a heated oven leads to subsequent dehydration, carbonization and sulfonation of the carbohydrate structure, in less than two seconds residence time. Acid site concentrations ranging from 0.1 to 0.6 mmol g−1 can be obtained. Porosity can easily be introduced via salt templating, and can be adjusted by varying the loading and type of salt used. The highest surface area was obtained with Li2SO4, giving a BET surface area of 506 m2 g−1 and a mesopore size distribution between 2 and 8 nm. Fructose dehydration and inulin hydrolysis showed that the porous materials synthesized by salt templating are more active than the bulk ones, especially for inulin hydrolysis, for which the initial activity is enhanced by a factor of seven, making these materials competitive with the most active commercial resins.

SO3H-Containing Functional Carbon Materials: Synthesis, Structure, and Acid Catalysis

“…Nonconventional, in-situ sulfonation techniques have also been developed, some of which are discussed below. For example, Konwar et al , obtained SO 3 H-functionalized (0.32–1.24 mmol/g) meso–macroporous acidic carbons via mild pyrolysis (350–450 °C) and ion/H + -exchanging ice-templated, water-soluble polyelectrolyte polymers, i.e., Na–lignosulfonate/Na–polystyrenesulfonate (or their mixtures). , In a related work, Duyckaerts and co-workers produced mesoporous sulfonated carbons materials by one-step spray pyrolysis of an aqueous solution of sucrose as a carbon source, sulfuric acid as a sulfur source, and Li 2 SO 4 /Na 2 SO 4 as a structure-directing agent at 400–800 °C . In their work, carbon materials with a specific surface area of 506 m 2 /g and mesopore size distribution between 2 and 8 nm were produced using Li 2 SO 4 as the structure-directing agent …”

“…In fact, these materials are superior in terms of textural properties (pore size, surface area, etc.) and surface SO 3 H acidity. ,, …”

Hollow Nano- and Microstructures as Catalysts

“…Nevertheless, production rates of 30 g/h are reported, which substantially exceeds the amounts accessible by solution-based methods. However, for most of the protocols only the synthesis of hollow shells is described, − being the single-step encapsulation of nanoparticulate cargos more challenging in this case.…”

“…200 °C up to 1500 °C, spanning temperatures typical of spray drying and flame spray pyrolysis. Therefore, thermal stress is a main concern for the production of high-quality hollow spheres . Even though the synthesis of hollow spheres via spray pyrolysis from neat precursor solutions has been reported, additives, such as surfactants or carbohydrates like sucrose, which play a dual role of viscosity modulators and template (precursors), are often required to obtain hollow morphologies.…”

Aerosol‐Spray Pyrolysis toward Preparation of Nanostructured Materials for Batteries and Supercapacitors

“…Various materials, such as metals, metal alloys, oxides, carbon materials, etc., have been prepared through the aerosol‐spray technique. For instance, mesoporous carbon nanocapsules and particles, iron oxide nanoparticles within silica microspheres, nanoscale zerovalent iron–silica composites, carbon/silica composites or crystalline silicon carbide hollow spheres, porous TiO 2 nanoparticles and single crystalline TiOF 2 , Bi 2 Ti 2 O 7 , hollow spheres, and Ni and/or Ni x Pt 1− x alloy particles . In addition, various structures can be realized through the design and adjustment of the aerosol precursor solution (e.g., concentration, templates, components) ( Figure ) .…”