Bead-Shaped Mesoporous Alumina Adsorbents for Adsorption of Ammonia.

It is of great importance to remove toxic gases by efficient methods for recovering the atmosphere to safe levels. The adsorption of the toxic gas molecules on solid adsorbents is one of the most useful techniques because of its simple operation and economic feasibility. Here, we report the uniform Bead-Shaped Mesoporous Alumina (BSMA) with tunable particle size for use as an adsorbent for removal of toxic ammonia. The BSMA particles with tunable diameters were synthesized by means of a sol-gel reaction of Al(NO3)3∙9H2O as an alumina precursor in the presence of chitosan as a template. When the ammonia solution is added dropwise to the prepared viscose mixture containing chitosan, acetic acid, and the alumina precursor solution, the sol-gel condensation reaction of the alumina precursor occurs in the chitosan polymer metrics, resulting in bead-shaped chitosan-aluminum hydroxide particles. Then, final Bead-Shaped Mesoporous Alumina (BSMA) particles are obtained by calcination at a high temperature. During the synthesis, changing the mole ratio of the chitosan template to the alumina precursor allowed the particle diameter of the final bead sample to be finely controlled. In addition, the prepared BSMA particles have well-developed mesoporous characteristics with relatively large surface areas, which are beneficial for adsorption of gas molecules. In an ammonia adsorption experiment, the BSMA-1.5 sample, which has the smallest particle diameter among the bead samples, was the best in terms of adsorption capacity. In this manuscript, we systemically discuss the relationship between the characteristics of BSMA samples and their adsorption of ammonia.

Amine-Functionalized Covalent Organic Framework for Efficient SO2 Capture with High Reversibility.

Removing sulfur dioxide (SO2) from exhaust flue gases of fossil fuel power plants is an important issue given the toxicity of SO2 and subsequent environmental problems. To address this issue, we successfully developed a new series of imide-linked covalent organic frameworks (COFs) that have high mesoporosity with large surface areas to support gas flowing through channels; furthermore, we incorporated 4-[(dimethylamino)methyl]aniline (DMMA) as the modulator to the imide-linked COF. We observed that the functionalized COFs serving as SO2 adsorbents exhibit outstanding molar SO2 sorption capacity, i.e., PI-COF-m10 record 6.30 mmol SO2 g-1 (40 wt%). To our knowledge, it is firstly reported COF as SO2 sorbent to date. We also observed that the adsorbed SO2 is completely desorbed in a short time period with remarkable reversibility. These results suggest that channel-wall functional engineering could be a facile and powerful strategy for developing mesoporous COFs for high-performance reproducible gas storage and separation.

Hydrolysis of ionic cellulose to glucose.

Hydrolysis of ionic cellulose (IC), 1,3-dimethylimidazolium cellulose phosphite, which could be synthesized from cellulose and dimethylimidazolium methylphosphite ([Dmim][(OCH3)(H)PO2]) ionic liquid, was conducted for the synthesis of glucose. The reaction without catalysts at 150°C for 12h produced glucose with 14.6% yield. To increase the hydrolysis yield, various acid catalysts were used, in which the sulfonated active carbon (AC-SO3H) performed the best catalytic activity in the IC hydrolysis. In the presence of AC-SO3H, the yields of glucose reached 42.4% and 53.9% at the reaction condition of 150°C for 12h and 180°C for 1.5h, respectively; however the yield decreased with longer reaction time due to the degradation of glucose. Consecutive catalyst reuse experiments on the IC hydrolysis demonstrated the catalytic activity of AC-SO3H persisted at least through four successive uses.

Ionic-liquid-derived, water-soluble ionic cellulose.

A new type of water-soluble ionic cellulose was obtained by means of the dissolution of cellulose in dimethylimidazolium methylphosphite at elevated temperatures over 120 °C. FTIR spectroscopy, (1)H and (13)C NMR spectroscopy, and elemental analysis results revealed that the repeating unit of the water-soluble cellulose consists of a dialkylimidazolium cation and a phosphite anion bonded to cellulose. The degree of phosphorylation on the cellulose chain was between 0.4 and 1.3 depending on the reaction temperature and time. With an increasing degree of phosphorylation, water solubility was increased. Scanning electron microscopy and X-ray diffraction analyses revealed that the cellulose crystalline phase in the parent crystalline cellulose changed to an amorphous phase upon transformation into ionic cellulose. Thermogravimetric analysis showed the prepared phosphorylated cellulose was stable over 250 °C and a substantial amount of residue remained at 500 °C.