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RISS 인기검색어
- 검색키워드
- 저자 : Dabbawala, A.A. (검색결과 4 건)
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Dabbawala, Aasif A.,Alhassan, Saeed M.,Mishra, Dinesh K.,Jegal, Jonggeon,Hwang, Jin-Soo Elsevier 2018 Molecular catalysis Vol.454 No.-
<P>Mesoporous sulfated titania (MST), a solid acid catalyst has been prepared in one step by organic template free straightforward hydrolysis of titanium oxysulfate and subsequent calcination at different temperatures. The resultant nano-sized MST catalysts showed remarkable catalytic performances in solvent free cyclodehydration of sorbitol as compared to sulfated TiO2 prepared by conventional method. The catalyst activity of MST catalysts varied with calcination temperature and MST-450 (calcined at 450 degrees C) exhibited highest catalytic activity and isosorbide selectivity. The MST-450 catalyzed this dehydration reaction at comparatively lower reaction temperature and produced isosorbide with high selectivity in short reaction time. The complete conversion of sorbitol with 70% isosorbide selectivity was achieved in 2 h at 180 degrees C. The high catalytic activity of MST catalyst attributes to its high specific surface area, large pore size and hence facile diffusion of reactants into the pores and ease to access acid sites. Moreover, the effects of calcination temperature, sulfur content, catalyst amount, reaction temperature and reaction time on conversion and selectivity were studied and the catalyst was also reused.</P>
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Mishra, Dinesh Kumar,Dabbawala, Aasif A.,Truong, Cong Chien,Alhassan, Saeed M.,Jegal, Jonggeon,Hwang, Jin Soo Elsevier 2018 Journal of industrial and engineering chemistry Vol.68 No.-
<P><B>Abstract</B></P> <P>Lactose is a reducing disaccharide consisting of two different monosaccharides such as galactose and glucose. The hydrogenation of lactose to lactitol is a formidable challenge because it is a complex process and several side products are formed. In this work, we synthesized Ru–Ni bimetallic nanohybrids as efficient catalysts for selective lactose hydrogenation to give selective lactitol. Ru–Ni bimetallic nanohybrids with Ru–NiO<I> <SUB>x</SUB> </I> (<I>x</I> =1, 5, and 10wt%) are prepared by impregnating Ru and Ni salts precursors with TiO<SUB>2</SUB> used as support material. Ru–Ni bimetallic nanohybrids (represented as 5Ru–5NiO/TiO<SUB>2</SUB>) catalyst is found to exhibit the remarkably high selectivity of lactitol (99.4%) and turnover frequency i.e. (374h<SUP>−1</SUP>). In contrast, monometallic Ru/TiO<SUB>2</SUB> catalyst shows poor performance with (TOF=251h<SUP>−1</SUP>). The detailed characterizations confirmed a strong interaction between Ru and NiO species, demonstrating a synergistic effect on the improvement on lactitol selectivity. The impregnation-reduction method for the preparation of bimetallic Ru–NiO/TiO<SUB>2</SUB> catalyst promoted Ru nanoparticles dispersed on NiO and intensified the interaction between Ru and NiO species. Ru–NiO/TiO<SUB>2</SUB> efficiently catalyzed the hydrogenation of lactose to lactitol with high yield/selectivity at almost complete conversion of lactose at 120°C and 55bar of hydrogen (H<SUB>2</SUB>) pressure. Moreover, Ru–NiO/TiO<SUB>2</SUB> catalyst could also be easily recovered and reused up to four runs without notable change in original activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly active supported Ru–Ni bimetallic catalysts with NiO are prepared. </LI> <LI> Bimetallic Ru–5NiO/TiO<SUB>2</SUB> catalyst shows high selectivity to lactitol (99.4%). </LI> <LI> Optimization and kinetics studies of lactose hydrogenation. </LI> <LI> Bimetallic Ru–5NiO/TiO<SUB>2</SUB> catalyst is reused up to several consecutive times. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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Mishra, D.K.,Dabbawala, A.A.,Park, J.J.,Jhung, S.H.,Hwang, J.S. Elsevier Science Publishers 2014 CATALYSIS TODAY - Vol.232 No.-
HY zeolite (HYZ) supported ruthenium (Ru) nanoparticles catalyst (Ru/HYZ) is prepared by simple impregnation method and is characterized by using energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), CO chemisorption and inductively coupled plasma (ICP) mass spectrometry. The catalyst Ru/HYZ is evaluated in hydrogenation of d-glucose and hydrogenation experiments to produce a selective product d-sorbitol were conducted batch wise in a three-phase laboratory scale reactor. The kinetics studies of d-glucose hydrogenation using the catalyst Ru/HYZ were carried out. In the operating regime studied the rate of reaction showed first orders dependency with respect to d-glucose and hydrogen. For affording maximum d-glucose conversion, yield and selectivity to d-sorbitol, the reaction conditions were also optimized.
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Dinesh Kumar Mishra,Aasif A. Dabbawala,Cong Chien Truong,Saeed M. Alhassan,Jonggeon Jegal,황진수 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.68 No.-
Lactose is a reducing disaccharide consisting of two different monosaccharides such as galactose and glucose. The hydrogenation of lactose to lactitol is a formidable challenge because it is a complex process and several side products are formed. In this work, we synthesized Ru–Ni bimetallic nanohybrids as efficient catalysts for selective lactose hydrogenation to give selective lactitol. Ru–Ni bimetallic nanohybrids with Ru–NiOx (x = 1, 5, and 10 wt%) are prepared by impregnating Ru and Ni salts precursors with TiO2 used as support material. Ru–Ni bimetallic nanohybrids (represented as 5Ru–5NiO/TiO2) catalyst is found to exhibit the remarkably high selectivity of lactitol (99.4%) and turnover frequency i.e. (374 h−1). In contrast, monometallic Ru/TiO2 catalyst shows poor performance with (TOF = 251 h−1). The detailed characterizations confirmed a strong interaction between Ru and NiO species, demonstrating a synergistic effect on the improvement on lactitol selectivity. The impregnation-reduction method for the preparation of bimetallic Ru–NiO/TiO2 catalyst promoted Ru nanoparticles dispersed on NiO and intensified the interaction between Ru and NiO species. Ru–NiO/TiO2 efficiently catalyzed the hydrogenation of lactose to lactitol with high yield/selectivity at almost complete conversion of lactose at 120 °C and 55 bar of hydrogen (H2) pressure. Moreover, Ru–NiO/TiO2 catalyst could also be easily recovered and reused up to four runs without notable change in original activity.
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