Norihito Hiyoshi

Adsorption of carbon dioxide on modified mesoporous materials in the presence of water vapor

Abstract Aminosilane modified mesoporous silica as novel adsorbent for CO 2 capture and separation from flue gases was prepared by grafting various aminosilanes; i.e., (3-aminopropyl)triethoxysilane (APS), N-(2-aminoethyl)-3-aminopropyltriethoxysilane (AEAPS) and (3-trimethoxysilylpropy l)diemylenetriamine (TA), on mesoporous silica, SBA-15. Pore walls of SBA-15 were modified uniformly with these aminosilanes and relatively high surface area and uniform pore size were retained. Adsorption capacities of CO 2 in the presence of water were compared with that in the absence of water by a flow method. It was found that adsorption capacities of aminosilane modified SBA-15 under wet condition were comparable to that under dry condition. In particular, the adsorption capacity of TA-anchored SBA-15 reached 1.28 mol.kg 1 in the presence of water vapor at 333 K. In addition, these adsorbents were completely regenerated by heating up to 423 K in He flow.

Selective oxidation of n-butane over novel V-P-O/silica-composites prepared through intercalation and exfoliation of layered precursor

Vanadium-phosphorus oxides-silica composites were prepared through intercalation-exfoliation of layered VOPO 4 2H 2 O. Intercalated compounds of VOPO 4 2H 2 O with 4-butylaniline, acrylamide and 2-octanol were formed retaining its morphology and lattice structure. These compounds were exfoliated in polar solvents into delaminated sheets. The composites of silica were obtained by impregnating silica with the solution containing the delaminated layers. It was found that the SiO 2 -composite obtained by exfoliation and reduction only with 2- octanol was highly selective (54%-selectivity), while the SiO 2 -intercalated materials with the N-containing compounds were less selective.

Vapor phase methylation of pyridine with CO−H2 and CO2−H2 over a Ni catalyst

Pyridine was methylated selectively to 2-picoline with CO−H2 and with CO2−H2 over a Ni catalyst. 2,6-lutidine was producedvia the methylation of 2-picoline.

Discovery of a new crystalline phase: BiGeO2(OH)2(NO3)

A new crystalline phase has been discovered in the Bi2O3–GeO2–HNO3–H2O quartet system. The new phase was slowly precipitated at room temperature under atmospheric pressure from a strongly acidic aqueous solution (pH ~0.2) containing dissolved bismuth oxide, germanium oxide, dilute ammonia, and nitric acid. Characterization and crystal structure analyses were carried out by means of powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), thermogravimetry (TG)–mass spectrometric analysis, and solid-state nuclear magnetic resonance (NMR) spectroscopy. The molecular formula was established as BiGeO2(OH)2(NO3). The crystal structure of this new phase was elucidated from PXRD data by a combination of direct and charge-flipping methods. The new phase was found to have the space group Pbca with lattice parameters of a = 1.145510(10) nm, b = 0.495346(5) nm, and c = 1.81676(2) nm. This new phase was observed to possess a layered structure consisting of BiO6 polyhedra, GeO5 trigonal bipyramids and nitrate ions.

Development of novel nano/meso-porous materials for CO2 capture & separation

Publisher Summary This chapter presents a study in which amine-modified mesoporous silica molecular sieve SBA-15 is prepared as a “water-tolerant adsorbents,” which can adsorb CO2 in the presence of water vapor. Moreover, the study also examines the applicability for pressure (and/or temperature) swing adsorption (PTSA) process by CO2 adsorption–desorption measurement in a flow system. In this study, amine-modified mesoporous silica as novel adsorbent is prepared by blending various aminosilanes; i.e., (3-aminopropyl) triethoxysilane (APS), N-(2-aminoethyl)-3-aminopropyltriethoxysilane (AEAPS) and (3-trimethoxysilylpropyl)diethylenetriamine (TA), on mesoporous silica, SBA-15. This mixture is capable for CO2 capture and separation from flue gases. Pore walls of SEA-15 are modified uniformly with these aminosilanes, and relatively high surface area and uniform pore size are retained. Adsorption capacities of CO2 in the presence of water vapor are compared with that in the absence of water by a flow method. It was found that adsorption capacities of amine-modified SBA-15 under the wet condition are comparable to that under the dry condition. In particular, the adsorption capacity of TA anchored SBA-15 reaches 1.28 molkg-1 in presence of water vapor at 333 K. In addition, these adsorbents are completely regenerated by heating up to 423 K in the He flow.

55 A highly selective vanadyl pyrophosphate synthesized by exfoliation-reduction in mixed alcohols for n-butane oxidation

Abstract Intercalation-exfoliation of VOPO 4 -2H 2 O crystallites (10 μm in size) in three kinds of butanol (1-, 2- and iso-butanol) and reduction with the butanol brought about thin layers of precursor, VOHPO 4 0.5H 2 O, with the different shape and size. A small fragment-shape vanadyl pyrophosphate obtained by exfoliation in 2-butanol and the sequent reduction in a mixture of 2-butanol-ethanol was highly selective for the oxidation of n -butane.