• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2311-2315
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• 2011

Alumina supported polyphosphoric acid (PPA/$Al_2O_3$) was successfully prepared by impregnation of alumina support by polyphosphoric acid and characterized using FT-IR spectroscopy, the $N_2$ adsorption/desorption analysis (BET), thermal analysis (TG/DTG), and X-ray diffraction (XRD) techniques. The catalytic behavior of this new solid acid supported heterogeneous catalyst was checked in the synthesis of 14-aryl-14H-dibenzo[a, j]xanthenes by cyclocondensation reaction of ${\beta}$-naphthol and aryl aldehydes under solvent-free conditions. The results showed that the novel catalyst has high activity and the desired products were obtained in very short reaction times with high yields. Moreover, the catalyst can be easily recovered by filtration and reused at least three times with only slight reduction in its catalytic activity.

• Bulletin of the Korean Chemical Society
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• v.29 no.7
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• pp.1320-1322
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• 2008

Phosphomolybdic acid supported on silica gel (PMA-$SiO_2$) is an efficient catalyst for the activation of TMSCN for the facile cyanosilylation of various aldehydes. Cyano transfer from TMSCN to aldehyde proceeds smoothly at rt in presence of 0.8 mol % of PMA-$SiO_2$ leading to a range of cyanosilylether in excellent yield (mostly over 93%) within short reaction time (30 min). The catalyst can be recovered and reused several times without loss of activity.

• Bulletin of the Korean Chemical Society
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• v.21 no.10
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• pp.1015-1019
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• 2000

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.65-72
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• 2019

In this study, heterogeneous ion exchange membranes were prepared by casting method with various mixing ratios of PPO ion-selective solution and ion exchange resin. Then heterogeneous bipolar membranes were prepared by using this. The water content of heterogeneous cation and anion exchange membranes were 60~80% respectively, the ion exchange capacity was 2.81~3.26 meq/g, 2.31~2.74 meq/g and electrical resistances were $1.65{\sim}1.45{\Omega}{\cdot}cm^2$ and $1.55{\sim}1.05{\Omega}{\cdot}cm^2$. The tensile strength of heterogeneous bipolar membrane was lower than that of PPO resin before functionalization ($700Kg_f/cm^2$). The tensile strength of heterogeneous bipolar membrane with catalyst layer was lower than that of non-catalytic heterogeneous bipolar membrane. The water splitting voltage of the heterogeneous bipolar membrane with catalyst layer was low and stable at a minimum of 1.7~1.8 V, maximum 3.9~4.0 V, and the water splitting voltage of the non-catalytic heterogeneous bipolar membrane was constant at 3.8~4.0 V.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1741-1744
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• 2013

A new polymeric catalyst was prepared by supporting $GaCl_3$ on cross-linked polyvinylpyrrolidone ($GaCl_3$/PVP). This catalyst was employed for efficient and regioselective ring-opening reaction of epoxides by various alcohols under solvent-free conditions at room temperature. In our procedure, this heterogeneous catalyst was used at neutral and mild reaction conditions to afford high yields of ${\beta}$-alkoxy alcohols. Also, regioselective conversion of epoxides to ${\beta}$-azidohydrines was accomplished by sodium azide in MeOH in the presence of $GaCl_3$/PVP at room temperature. $GaCl_3$/PVP is a non-hygroscopic and recoverable catalyst and is easily separated from reaction mixture by a simple filtration and re-used repeatedly. Also, this catalyst has good handling and can be stored for long time without any reducing of its reactivity.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2973-2979
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• 2010

The newly synthesized homogeneous chiral Co(III) salen complexes were anchored non-covalently on the acidic sites of mesoporous Al-SBA-15. The Bronsted and Lewis acidic sites are attributed to the immobilization of fluorine functionalized chiral salen complexes on the supports. XRD, BET, TEM, FT-IR and ESCA (XPS) analyses were performed to characterize the property of support, and the structure of new homogeneous and heterogeneous chiral Co salen catalyst. The homogeneous and heterogeneous catalysts could be applied in asymmetric ring opening of epichlorohydrine (ECH) by water. They showed very high enantioselectivity and a good yield up to 99% in the catalytic synthesis of optically active products.

• Carbon letters
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• v.27
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• pp.42-49
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• 2018

A citric acid functionalized graphene oxide nanocomposite was successfully synthesized and the structure and morphology of the nanocatalyst were comprehensively characterized by Fourier transform infrared spectroscopy, energy-dispersive X-ray analysis, X-ray diffraction patterns, atomic force microscopy images, scanning electron microscopy images, transmission electron microscopy images, and thermogravimetric analysis. The application of this nanocatalyst was exemplified in an important condensation reaction to give imidazole derivatives in high yields and short reaction times at room temperature. The catalyst shows high catalytic activity and could be reused after simple work up and easy purification for at least six cycles without significant loss of activity, which indicates efficient immobilizing of citrate groups on the surface of graphene oxide sheets.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.56-62
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• 2016

A heterogeneous $Bi_2S_3/TiO_2$ composite catalyst was synthesized via a green ultrasonic-assisted method and characterized by XRD, SEM, EDX, TEM analysis. The results clearly show that the $TiO_2$ particles were homogenously coated with $Bi_2S_3$ particles, indicating that $Bi_2S_3$ particle agglomeration was effectively inhibited after the introduction of anatase $TiO_2$. The Texbrite BA-L (TBA) degradation rate constant for $Bi_2S_3/TiO_2$ composites reached $8.27{\times}10^{-3}min^{-1}$ under visible light, much higher than the corresponding value of $1.04{\times}10^{-3}min^{-1}$ for $TiO_2$. The quantities of generated hydroxyl radicals can be analyzed by DPCI degradation, which shows that under visible light irradiation, more electron-hole pairs can be generated. Finally, the possible mechanism for the generation of reactive oxygen species under visible-light irradiation was proposed as well. Our result shows the significant potential of $Bi_2S_3$-semiconductor-based $TiO_2$ hybrid materials as catalysts under visible light for the degradation of industry dye effluent substances.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2584-2592
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• 2011

Nickel nanoparticle-poly(N-vinyl-2-pyrrolidone)/$TiO_2-ZrO_2$ composite (Ni-PVP/$TiO_2-ZrO_2$) was prepared by in situ polymerization method. The physical and chemical properties of Ni-PVP/$TiO_2-ZrO_2$ were investigated by XRD, FT-IR, BET, TGA, SEM and TEM techniques. The catalytic performance of this novel heterogeneous catalyst was determined for the Suzuki-Miyaura cross-coupling reaction between aryl halides and phenylboronic acid in the presence of methanol-water mixture as solvent. The effects of reaction temperature, the amount of catalyst, amount of support, solvent, and amount of metal for the synthesis of Ni-PVP/$TiO_2-ZrO_2$, were investigated as well as recyclability of the heterogeneous composite. The catalyst used for this synthetically useful transformation showed considerable level of reusability besides very good activity.

• Applied Chemistry for Engineering
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• v.26 no.6
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• pp.743-745
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• 2015

Amorphous cobalt phosphates were synthesized with their distinct morphology by controlling the amount of base in the synthetic condition. The crystallinity and morphology of cobalt phosphates were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The prepared cobalt phosphates were applied as a heterogeneous catalyst for generating hydrogen gas from the hydrolysis reaction of sodium borohydride. We found that the catalyst prepared using the least amount of base condition at room temperature showed a plate shape with less than 10 nm thickness, which resulted in the best catalytic activity among all catalysts due to the large surface area.