Apurba Sinhamahapatra | Daegu Gyeongbuk Institute of Science and Technology (original) (raw)

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Papers by Apurba Sinhamahapatra

Catalysis Communications, 2011

Styrene epoxidation reaction has drawn attention from both academia and industry. After the synth... more Styrene epoxidation reaction has drawn attention from both academia and industry. After the synthesis of SBA-15 the research on mesoporous family has enriched by TUD-1 mesoporous material. Doped and undoped TUD-1, has been exploited for various oxidation reactions either as such or as a support for different active component. In this paper we report the characterization of recently developed Ga-TUD-1 catalyst with three different Ga/Si ratio (1/100, 2/100, 4/100) by BET SA, FTIR, UV–Vis, DRIFT, SEM, TEM, 29Si NMR techniques. A steady activity of the catalyst towards styrene epoxidation without any loss of efficiency up to 48 h of reaction was found.► Styrene epoxidation by using H2O2 over mesoporous catalyst in an atom efficient path. ► Cooperative role of lewis and bronsted acid sites over the catalyst surface. ► Retaining the morphology and structure of mesoporous TUD-1 catalyst after Ga doping. ► Steady activity upto 48 h reaction at mild condition.

Applied Catalysis B-environmental, 2011

Synthesis of various industrially important fine chemicals under microwave irradiation (MWI) in s... more Synthesis of various industrially important fine chemicals under microwave irradiation (MWI) in solvent-free conditions over mesoporous zirconium phosphate (m-ZrP) is reported. m-ZrP is synthesized by MWI in basic medium using a precursor solution of zirconium carbonate complex as zirconium source and CTAB as a pore-directing agent. MWI time and MWI power were found to have significant influence on the textural properties of synthesized m-ZrP. Microscopic analyses of the synthesized m-ZrP indicate the presence of worm like pores with spherical morphology. DRIFT analysis of pyridine adsorbed m-ZrP and NH3-TPD measurements indicate the presence of appreciable amount of Brönsted acid sites. Synthesized m-ZrP exhibits high catalytic activity towards Claisen–Schmidt condensation reaction in solvent-free conditions under microwave irradiation. The m-ZrP showed high activity towards other acid catalyzed reactions such as Friedel–Craft benzylation, Pechmann condensation and carbonyl group protection reaction, and also for the synthesis of benzo-xanthenes in solvent-free conditions under MWI. The catalytic activity of m-ZrP is substantially higher than that of conventional layered ZrP. The synthesized catalysts are re-usable for at least five times after regeneration, without losing their catalytic activity significantly.► Microwave assisted synthesis of mesoporous zirconium phosphate (m-ZrP). ► m-ZrP is an efficient catalyst for fine chemicals under microwave irradiation. ► 98% conversion with 99% selectivity of chalcone was obtained in 10 min. ► The developed procedure is convenient, economical and time efficient.

Materials Chemistry and Physics, 2011

Rectangular hydromagnesite microsheet is prepared by simple solution route through controlled hyd... more Rectangular hydromagnesite microsheet is prepared by simple solution route through controlled hydrolysis-condensation of magnesium chloride in urea solution using ethylene glycol (EG) as a bifunctional cosolvent. Calcination of the hydromagnesite sheets at 450 • C produces MgO without any alteration in the morphology. The MgO sheets were of 2-3 side length and 4-5 nm thickness, and made of highly crystalline MgO nano-particles, which show reasonably high BET surface area of 106 m 2 g −1 .

Applied Catalysis A-general, 2011

The high surface area three-dimensional porous catalyst has been prepared and characterized by TE... more The high surface area three-dimensional porous catalyst has been prepared and characterized by TEM, BET S.A, low angle XRD, 29Si MAS NMR, NH3 TPD techniques. A simple, efficient and rapid method for the green synthesis of α-aminonitriles has been demonstrated over a new mesoporous gallosilicate catalyst Ga-TUD-1. The solventless technique has been applied for the synthesis of a range of compounds with variable functionality with excellent yield and selectivity. The catalyst has been recycled four times with reproducible yield..▶ Ga-TUD-1, a new mesoporous catalyst developed by non hydrothermal sol–gel method. ▶ Characterized by TEM, atom mapping, XRD, NH3 TPD, 29Si NMR, BET SSA method. ▶ Found to be highly acidic having large number of Bronsted and Lewis acid sites. ▶ The catalyst applied in multicomponent organic synthesis of α-aminonitriles. ▶ Reused several times with reproducible activity.

Applied Catalysis A-general, 2010

Mesoporous zirconium phosphate (m-ZrP) having high specific surface area and narrow pore size dis... more Mesoporous zirconium phosphate (m-ZrP) having high specific surface area and narrow pore size distributions is synthesized in basic medium using zirconium carbonate as source of zirconium. The concentration of phosphate in precursor solutions, as well as the calcination temperature, is found to influence the textural properties and acidity of synthesized m-ZrP significantly. Microscopic analysis indicates the presence of worm like

Applied Catalysis A-general, 2011

A novel, convenient, one step synthetic procedure for the synthesis of mesoporous sulfated zircon... more A novel, convenient, one step synthetic procedure for the synthesis of mesoporous sulfated zirconia (m-SZ) using zirconium carbonate complex and its use as solid acid catalyst for the acetalization of different carbonyl compound is reported. The high specific BET surface area (234 m 2 g −1 ) of m-SZ is achieved after the removal of the surfactant (cetyltrymethylammonium bromide, CTAB) through calcination at 550 • C for 6 h. Microscopic analysis indicated the presence of spherical particles with worm like pores. DRIFT (diffuse reflectance FTIR) of pyridine adsorbed m-SZ and NH 3 -TPD (temperature programmed desorption) analysis suggested the presence of appreciable amount of Brönsted acid sites. The synthesized m-SZ showed high catalytic activity towards protection of carbonyl compounds through acetal/ketal formation. For the open ketal (from cyclohexanone and methanol) 97% conversion with 100% selectivity was obtained in 1 h at room temperature under solvent free condition. The catalyst can be easily recycled after separation from the reaction system without considerable loss in catalytic activity.

Materials Research Bulletin, 2011

MgO nano-rods of several microns in length and 50–100 nm in width were prepared by calcining nesq... more MgO nano-rods of several microns in length and 50–100 nm in width were prepared by calcining nesquehonite phase, obtained by simple precipitation using (NH4)2CO3 under ambient condition. The MgO nano-rod with reasonably high surface area (75–120 m2 g−1) exhibits strong activity in solvent-free base catalyzed Claisen-Schmidt condensation giving 99% conversion in 2 h and is easily recyclable with no significant change in catalytic activity. Presence of numerous basic sites of different strengths (surface hydroxyl groups, low coordinate O2− sites) is attributed to the observed effect.► Simple solution route for preparing nesquehonite rods. ► Nano-building block based MgO rods as base catalyst. ► Calcination of nesquehonite in nitrogen gives highly active MgO catalyst. ► Large surface area and active site density is attributed to the strong activity.

Applied Catalysis A-general, 2011

Mesoporous zirconium phosphate (m-ZrP) is used as a solid acid catalyst for the synthesis of coum... more Mesoporous zirconium phosphate (m-ZrP) is used as a solid acid catalyst for the synthesis of coumarins via Pechmann condensation reaction and gave high catalytic activity for the condensation of phenols and ethyl acetoacetate in both conventional heating as well as microwave assisted method. The condensation reaction is studied in detail by varying the reaction parameters like effect of solvent, molar ratio of the reactants, temperature, and catalyst loading. Among the substituted phenols, m-amino phenol is more reactive and 100% yield is obtained in very short time at low temperature due to the presence of ring activating amine group in meta position. The m-ZrP is also active even for simple phenol and 57% yield of 4-methyl coumarin is obtained in conventional heating method. Microwave assisted synthetic method is found to be advantageous over conventional heating for the synthesis of coumarins, as it provides improved yield in very less time.

Catalysis Communications, 2011

Styrene epoxidation reaction has drawn attention from both academia and industry. After the synth... more Styrene epoxidation reaction has drawn attention from both academia and industry. After the synthesis of SBA-15 the research on mesoporous family has enriched by TUD-1 mesoporous material. Doped and undoped TUD-1, has been exploited for various oxidation reactions either as such or as a support for different active component. In this paper we report the characterization of recently developed Ga-TUD-1 catalyst with three different Ga/Si ratio (1/100, 2/100, 4/100) by BET SA, FTIR, UV–Vis, DRIFT, SEM, TEM, 29Si NMR techniques. A steady activity of the catalyst towards styrene epoxidation without any loss of efficiency up to 48 h of reaction was found.► Styrene epoxidation by using H2O2 over mesoporous catalyst in an atom efficient path. ► Cooperative role of lewis and bronsted acid sites over the catalyst surface. ► Retaining the morphology and structure of mesoporous TUD-1 catalyst after Ga doping. ► Steady activity upto 48 h reaction at mild condition.

Applied Catalysis B-environmental, 2011

Synthesis of various industrially important fine chemicals under microwave irradiation (MWI) in s... more Synthesis of various industrially important fine chemicals under microwave irradiation (MWI) in solvent-free conditions over mesoporous zirconium phosphate (m-ZrP) is reported. m-ZrP is synthesized by MWI in basic medium using a precursor solution of zirconium carbonate complex as zirconium source and CTAB as a pore-directing agent. MWI time and MWI power were found to have significant influence on the textural properties of synthesized m-ZrP. Microscopic analyses of the synthesized m-ZrP indicate the presence of worm like pores with spherical morphology. DRIFT analysis of pyridine adsorbed m-ZrP and NH3-TPD measurements indicate the presence of appreciable amount of Brönsted acid sites. Synthesized m-ZrP exhibits high catalytic activity towards Claisen–Schmidt condensation reaction in solvent-free conditions under microwave irradiation. The m-ZrP showed high activity towards other acid catalyzed reactions such as Friedel–Craft benzylation, Pechmann condensation and carbonyl group protection reaction, and also for the synthesis of benzo-xanthenes in solvent-free conditions under MWI. The catalytic activity of m-ZrP is substantially higher than that of conventional layered ZrP. The synthesized catalysts are re-usable for at least five times after regeneration, without losing their catalytic activity significantly.► Microwave assisted synthesis of mesoporous zirconium phosphate (m-ZrP). ► m-ZrP is an efficient catalyst for fine chemicals under microwave irradiation. ► 98% conversion with 99% selectivity of chalcone was obtained in 10 min. ► The developed procedure is convenient, economical and time efficient.

Materials Chemistry and Physics, 2011

Rectangular hydromagnesite microsheet is prepared by simple solution route through controlled hyd... more Rectangular hydromagnesite microsheet is prepared by simple solution route through controlled hydrolysis-condensation of magnesium chloride in urea solution using ethylene glycol (EG) as a bifunctional cosolvent. Calcination of the hydromagnesite sheets at 450 • C produces MgO without any alteration in the morphology. The MgO sheets were of 2-3 side length and 4-5 nm thickness, and made of highly crystalline MgO nano-particles, which show reasonably high BET surface area of 106 m 2 g −1 .

Applied Catalysis A-general, 2011

The high surface area three-dimensional porous catalyst has been prepared and characterized by TE... more The high surface area three-dimensional porous catalyst has been prepared and characterized by TEM, BET S.A, low angle XRD, 29Si MAS NMR, NH3 TPD techniques. A simple, efficient and rapid method for the green synthesis of α-aminonitriles has been demonstrated over a new mesoporous gallosilicate catalyst Ga-TUD-1. The solventless technique has been applied for the synthesis of a range of compounds with variable functionality with excellent yield and selectivity. The catalyst has been recycled four times with reproducible yield..▶ Ga-TUD-1, a new mesoporous catalyst developed by non hydrothermal sol–gel method. ▶ Characterized by TEM, atom mapping, XRD, NH3 TPD, 29Si NMR, BET SSA method. ▶ Found to be highly acidic having large number of Bronsted and Lewis acid sites. ▶ The catalyst applied in multicomponent organic synthesis of α-aminonitriles. ▶ Reused several times with reproducible activity.

Applied Catalysis A-general, 2010

Mesoporous zirconium phosphate (m-ZrP) having high specific surface area and narrow pore size dis... more Mesoporous zirconium phosphate (m-ZrP) having high specific surface area and narrow pore size distributions is synthesized in basic medium using zirconium carbonate as source of zirconium. The concentration of phosphate in precursor solutions, as well as the calcination temperature, is found to influence the textural properties and acidity of synthesized m-ZrP significantly. Microscopic analysis indicates the presence of worm like

Applied Catalysis A-general, 2011

A novel, convenient, one step synthetic procedure for the synthesis of mesoporous sulfated zircon... more A novel, convenient, one step synthetic procedure for the synthesis of mesoporous sulfated zirconia (m-SZ) using zirconium carbonate complex and its use as solid acid catalyst for the acetalization of different carbonyl compound is reported. The high specific BET surface area (234 m 2 g −1 ) of m-SZ is achieved after the removal of the surfactant (cetyltrymethylammonium bromide, CTAB) through calcination at 550 • C for 6 h. Microscopic analysis indicated the presence of spherical particles with worm like pores. DRIFT (diffuse reflectance FTIR) of pyridine adsorbed m-SZ and NH 3 -TPD (temperature programmed desorption) analysis suggested the presence of appreciable amount of Brönsted acid sites. The synthesized m-SZ showed high catalytic activity towards protection of carbonyl compounds through acetal/ketal formation. For the open ketal (from cyclohexanone and methanol) 97% conversion with 100% selectivity was obtained in 1 h at room temperature under solvent free condition. The catalyst can be easily recycled after separation from the reaction system without considerable loss in catalytic activity.

Materials Research Bulletin, 2011

MgO nano-rods of several microns in length and 50–100 nm in width were prepared by calcining nesq... more MgO nano-rods of several microns in length and 50–100 nm in width were prepared by calcining nesquehonite phase, obtained by simple precipitation using (NH4)2CO3 under ambient condition. The MgO nano-rod with reasonably high surface area (75–120 m2 g−1) exhibits strong activity in solvent-free base catalyzed Claisen-Schmidt condensation giving 99% conversion in 2 h and is easily recyclable with no significant change in catalytic activity. Presence of numerous basic sites of different strengths (surface hydroxyl groups, low coordinate O2− sites) is attributed to the observed effect.► Simple solution route for preparing nesquehonite rods. ► Nano-building block based MgO rods as base catalyst. ► Calcination of nesquehonite in nitrogen gives highly active MgO catalyst. ► Large surface area and active site density is attributed to the strong activity.

Applied Catalysis A-general, 2011

Mesoporous zirconium phosphate (m-ZrP) is used as a solid acid catalyst for the synthesis of coum... more Mesoporous zirconium phosphate (m-ZrP) is used as a solid acid catalyst for the synthesis of coumarins via Pechmann condensation reaction and gave high catalytic activity for the condensation of phenols and ethyl acetoacetate in both conventional heating as well as microwave assisted method. The condensation reaction is studied in detail by varying the reaction parameters like effect of solvent, molar ratio of the reactants, temperature, and catalyst loading. Among the substituted phenols, m-amino phenol is more reactive and 100% yield is obtained in very short time at low temperature due to the presence of ring activating amine group in meta position. The m-ZrP is also active even for simple phenol and 57% yield of 4-methyl coumarin is obtained in conventional heating method. Microwave assisted synthetic method is found to be advantageous over conventional heating for the synthesis of coumarins, as it provides improved yield in very less time.