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Oliver Krocher - One of the best experts on this subject based on the ideXlab platform.
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promotion of Ammonium Formate and formic acid decomposition over au tio2 by support basicity under scr relevant conditions
ACS Catalysis, 2015Co-Authors: Manasa Sridhar, Jeroen A Van Bokhoven, Oliver Krocher, Martin Elsener, Davide FerriAbstract:This work demonstrates the rational design of a dedicated hydrolysis catalyst for application in the selective catalytic reduction (SCR) of NOx. Modification of titania by lanthanum prior to gold deposition entailed highly improved catalytic activities for Ammonium Formate (AmFo) and formic acid decomposition under SCR-relevant conditions stemming from dual phenomena: particle size effect and base effect. Smaller gold particles were stabilized, and there was higher uptake of CO2 and formic acid, as demonstrated by HAADF-STEM and in situ DRIFT analyses, respectively. The difference in the activities between the lanthanum-modified, unmodified, and tungsten-modified catalysts was implicitly dictated by the formic acid coverage, which was in turn greatly increased in the presence of base. In situ DRIFT studies under reaction conditions identified Formate as a relevant reaction intermediate, under reaction conditions. Higher E-a,E-app alongside a higher pre-exponential factor (A), describe an underlying compensation effect originating from the contribution of enthalpy associated with the desorption of the strongly adsorbed Formate, which is consistent with the highly negative formic acid orders observed in the case of the lanthanum-modified catalysts. Gold is essential to achieve selectivity to CO2; its absence yields CO. The introduction of lanthanum to the catalytic system preferentially promoted the CO2 formation mechanism, enabling complete decomposition of formic acid selectively to CO2 at significantly lower gold loading and lower contact times, making it a promising candidate for decomposition of Formate-based ammonia precursors in the SCR process.
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effect of ammonia on the decomposition of Ammonium Formate over au tio2 under oxidizing conditions relevant to scr enhancement of formic acid decomposition rate and co2 production
Applied Catalysis A-general, 2014Co-Authors: Manasa Sridhar, Jeroen A Van Bokhoven, Oliver KrocherAbstract:Ammonium Formate (AmFo) and formic acid decomposition were carried out in the presence of excess O-2 and H2O over 0.5 wt%Au/TiO2 anatase monolithic catalysts using various contact times and temperatures between 160 degrees C and 300 degrees C, under spray conditions in a dedicated setup. A systematic investigation of ammonia influence on formic acid decomposition revealed a highly beneficial influence on the reaction rate and the CO2 yield in the temperature range 160-300 degrees C. Ammonia oxidation did not occur at any of the studied temperatures and space velocities. Both AmFo and a stoichiometric ammonia formic acid mixture exhibited identical homogeneous gas phase as well as heterogeneous catalytic decomposition behavior. With the introduction of ammonia at a concentration of only 0.25 molar equivalents, the pseudo-first-order rate constants for formic acid decomposition experienced close to 110% and 15% increase at 160 degrees C and 260 degrees C, respectively and dosing 12 molar equivalents of ammonia in the gas phase, the rate constants underwent nearly 8-fold increase at 160 degrees C, while at 260 degrees C, only two times increase was achieved. Increasing the ammonia to formic acid molar ratio from 0 to 12 lead to a steep increase in the CO2 yield from 18% to 75% at 160 degrees C, while a relatively smaller rise from 60% to 75% was observed at 260 degrees C. Activity testing of bare titania revealed an inhibitory effect of ammonia on formic acid decomposition to CO. Overall, it can be concluded that the presence of gold is critical for the realization of such an ammonia-induced enhancement of rate and CO2 yield. The obtained results are relevant for the application of Formate-based ammonia precursor compounds in the selective catalytic reduction of NOx in Diesel exhaust gases. (C) 2014 Elsevier B.V. All rights reserved.
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Ammonium Formate decomposition over au tio2 a unique case of preferential selectivity against nh3 oxidation
Chemical Communications, 2014Co-Authors: Manasa Sridhar, Daniel Peitz, Jeroen A Van Bokhoven, Oliver KrocherAbstract:The unique selectivity of Au/TiO2 for converting Ammonium Formate to CO2 in the presence of excess O2 and H2O without oxidising NH3 up to 300 °C is reported. The catalyst is highly stable and selective even after severe hydrothermal aging.
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a model gas study of Ammonium Formate methanamide and guanidinium Formate as alternative ammonia precursor compounds for the selective catalytic reduction of nitrogen oxides in diesel exhaust gas
Applied Catalysis B-environmental, 2009Co-Authors: Oliver Krocher, Martin Elsener, Eberhard JacobAbstract:Abstract Ammonium Formate, methanamide and guanidinium salts were investigated in model gas experiments and found to be suitable ammonia precursor compounds for the selective catalytic reduction (SCR) of nitrogen oxides since they decompose to ammonia over different metal oxide catalysts. The decomposition of Ammonium Formate started with thermolysis to formic acid and ammonia. Formic acid reacted further, mainly to water and CO (decarbonylation), but CO 2 formation (decarboxylation) was also observed. Under unsuitable reaction conditions, methanamide may be formed from ammonia and formic acid in an amidation reaction, and HCN may be formed from methanamide by dehydration. When methanamide was used as a reducing agent, it was emitted undecomposed at temperatures below 250 °C and formed HCN as a side-product at temperatures above 350 °C. Among the tested guanidinium salts, guanidinium Formate best met the requirements for a reducing agent in the SCR process, i.e., it decomposed at moderate temperatures with high selectivity, and it is highly water-soluble and stable when heated to 100 °C. For guanidinium Formate, a similar decomposition mechanism is proposed as that for Ammonium Formate. First, guanidinium Formate thermolyzes to guanidine and formic acid. Then, formic acid is decarbonylated and guanidine is assumed to hydrolyze in three steps, proceeding through urea and isocyanic acid (HNCO) as intermediates to the final product, ammonia. The formation of side-products was avoided for all three reducing agents when the reactor was filled with TiO 2 (anatase) as a catalyst and operated at 275–350 °C at low space velocities.
Channe D Gowda - One of the best experts on this subject based on the ideXlab platform.
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catalytic transfer hydrogenation of imines to secondary amines using inexpensive commercial zinc dust and Ammonium Formate
Journal of Chemical Research-s, 2006Co-Authors: K Abiraj, G R Srinivasa, Bhimareddy Dinesh, Channe D GowdaAbstract:A simple protocol for the chemo-selective reduction of imines to the corresponding secondary amines in good yield using inexpensive commercial zinc dust and Ammonium Formate in methanol at ambient temperature and pressure is described.
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conventional and microwave assisted hydrogenolysis using zinc and Ammonium Formate
ChemInform, 2004Co-Authors: Gejjalagere R. Srinivasa, S. N. Narendra Babu, C Lakshmi, Channe D GowdaAbstract:The selective deprotection of several N-Bzl amino derivatives to the corresponding amines and the removal of S-Bzl and O-Bzl groups from the protected amino acids with Ammonium Formate and commercial zinc dust are reported. Many other reducible or hydrogenolysable substituents such as halogens, methoxy, phenol, ester, acid, ethene, and Boc groups are unaffected.
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magnesium catalyzed proficient reduction of oximes to amines using Ammonium Formate
ChemInform, 2004Co-Authors: K Abiraj, Channe D GowdaAbstract:Abstract Various aldoximes and ketoximes were selectively reduced to the corresponding amines by catalytic transfer hydrogenation employing low cost magnesium powder and Ammonium Formate at room temperature. Many other functionalities such as halogens, –OH, –OCH3, –COOH and –CH3 remained unaffected. The hydrogenation is fast, mild, clean, cost effective and high yielding.
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facile synthesis of symmetrical functionalized biaryls from aryl halides catalyzed by commercial zinc dust using Ammonium Formate
ChemInform, 2004Co-Authors: K Abiraj, G R Srinivasa, Channe D GowdaAbstract:Reductive homocoupling of aryl halides in the presence of commercial zinc dust and Ammonium Formate in methanol produces biaryls in good to excellent yields. Aryl halides having either electron-donating or electron-withdrawing groups underwent smooth coupling to afford the corresponding symmetrical biaryls. Addition of 1 equiv of sodium hydroxide enhanced the coupling reaction rate. Commercial zinc dust is inexpensive, widely available and can be used without any auxiliary catalysts such as Pd(0) and/or Ni(0).
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magnesium Ammonium Formate promoted rapid low cost and selective reduction of nitro compounds
Indian Journal of Chemistry Section B-organic Chemistry Including Medicinal Chemistry, 2003Co-Authors: G R Srinivasa, K Abiraj, Channe D GowdaAbstract:The reduction of nitro compounds, both aliphatic and aromatic into corresponding amines has been achieved at room temperature in good yields by employing Ammonium Formate in the presence of low cost magnesium powder. The hydrogenation is fast and selective in the presence of other sensitive functionalities such as halogens, -OH, -OCH3, -CN, -COOR, -COOH etc. It was observed that, this system is equally compatible with existing methods, which employ expensive catalysts like palladium, platinum, ruthenium etc.
Manasa Sridhar - One of the best experts on this subject based on the ideXlab platform.
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promotion of Ammonium Formate and formic acid decomposition over au tio2 by support basicity under scr relevant conditions
ACS Catalysis, 2015Co-Authors: Manasa Sridhar, Jeroen A Van Bokhoven, Oliver Krocher, Martin Elsener, Davide FerriAbstract:This work demonstrates the rational design of a dedicated hydrolysis catalyst for application in the selective catalytic reduction (SCR) of NOx. Modification of titania by lanthanum prior to gold deposition entailed highly improved catalytic activities for Ammonium Formate (AmFo) and formic acid decomposition under SCR-relevant conditions stemming from dual phenomena: particle size effect and base effect. Smaller gold particles were stabilized, and there was higher uptake of CO2 and formic acid, as demonstrated by HAADF-STEM and in situ DRIFT analyses, respectively. The difference in the activities between the lanthanum-modified, unmodified, and tungsten-modified catalysts was implicitly dictated by the formic acid coverage, which was in turn greatly increased in the presence of base. In situ DRIFT studies under reaction conditions identified Formate as a relevant reaction intermediate, under reaction conditions. Higher E-a,E-app alongside a higher pre-exponential factor (A), describe an underlying compensation effect originating from the contribution of enthalpy associated with the desorption of the strongly adsorbed Formate, which is consistent with the highly negative formic acid orders observed in the case of the lanthanum-modified catalysts. Gold is essential to achieve selectivity to CO2; its absence yields CO. The introduction of lanthanum to the catalytic system preferentially promoted the CO2 formation mechanism, enabling complete decomposition of formic acid selectively to CO2 at significantly lower gold loading and lower contact times, making it a promising candidate for decomposition of Formate-based ammonia precursors in the SCR process.
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effect of ammonia on the decomposition of Ammonium Formate over au tio2 under oxidizing conditions relevant to scr enhancement of formic acid decomposition rate and co2 production
Applied Catalysis A-general, 2014Co-Authors: Manasa Sridhar, Jeroen A Van Bokhoven, Oliver KrocherAbstract:Ammonium Formate (AmFo) and formic acid decomposition were carried out in the presence of excess O-2 and H2O over 0.5 wt%Au/TiO2 anatase monolithic catalysts using various contact times and temperatures between 160 degrees C and 300 degrees C, under spray conditions in a dedicated setup. A systematic investigation of ammonia influence on formic acid decomposition revealed a highly beneficial influence on the reaction rate and the CO2 yield in the temperature range 160-300 degrees C. Ammonia oxidation did not occur at any of the studied temperatures and space velocities. Both AmFo and a stoichiometric ammonia formic acid mixture exhibited identical homogeneous gas phase as well as heterogeneous catalytic decomposition behavior. With the introduction of ammonia at a concentration of only 0.25 molar equivalents, the pseudo-first-order rate constants for formic acid decomposition experienced close to 110% and 15% increase at 160 degrees C and 260 degrees C, respectively and dosing 12 molar equivalents of ammonia in the gas phase, the rate constants underwent nearly 8-fold increase at 160 degrees C, while at 260 degrees C, only two times increase was achieved. Increasing the ammonia to formic acid molar ratio from 0 to 12 lead to a steep increase in the CO2 yield from 18% to 75% at 160 degrees C, while a relatively smaller rise from 60% to 75% was observed at 260 degrees C. Activity testing of bare titania revealed an inhibitory effect of ammonia on formic acid decomposition to CO. Overall, it can be concluded that the presence of gold is critical for the realization of such an ammonia-induced enhancement of rate and CO2 yield. The obtained results are relevant for the application of Formate-based ammonia precursor compounds in the selective catalytic reduction of NOx in Diesel exhaust gases. (C) 2014 Elsevier B.V. All rights reserved.
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Ammonium Formate decomposition over au tio2 a unique case of preferential selectivity against nh3 oxidation
Chemical Communications, 2014Co-Authors: Manasa Sridhar, Daniel Peitz, Jeroen A Van Bokhoven, Oliver KrocherAbstract:The unique selectivity of Au/TiO2 for converting Ammonium Formate to CO2 in the presence of excess O2 and H2O without oxidising NH3 up to 300 °C is reported. The catalyst is highly stable and selective even after severe hydrothermal aging.
Brindaban C Ranu - One of the best experts on this subject based on the ideXlab platform.
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hydrogenation of azides over copper nanoparticle surface using Ammonium Formate in water
Journal of Organic Chemistry, 2011Co-Authors: Sabir Ahammed, Amit Saha, Brindaban C RanuAbstract:Aryl azides undergo clean reduction by copper nanoparticles and Ammonium Formate in water. The surface hydrogen on copper nanoparticles is considered to be the active reducing species. A variety of functionalized aryl azides and aryl sulfonyl azides are reduced by this procedure to the corresponding amines with excellent chemoselectivity in high yields.
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highly chemoselective reduction of aromatic nitro compounds by copper nanoparticles Ammonium Formate
Journal of Organic Chemistry, 2008Co-Authors: Amit Saha, Brindaban C RanuAbstract:A highly chemoselective reduction of aromatic nitro compounds to the corresponding amino derivatives has been achieved by a combination of copper nanoparticles and Ammonium Formate in ethylene glycol at 120 °C. The reductions are successfully carried out in presence of a wide variety of other reducible functional groups in the molecule, such as Cl, I, OCH2Ph, NHCH2Ph, COR, COOR, CN, etc. The reactions are very clean and high yielding.
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catalytic hydrogen transfer reductions using Ammonium Formate a review
Journal of the Indian Chemical Society, 1998Co-Authors: Brindaban C Ranu, Arunkanti Sarkar, Sankar K Guchhait, Koena GhoshAbstract:An account of recent developments on selective reduction of several important functional groups by catalytic transfer hydrogenation using Ammonium Formate and palladium or nickel is presented. This includes reduction of nitro alcohols, α,β-unsaturated nitroalkenes, quinoline and isoquinoline, carbonyl functionalities, carbon-carbon double bond in conjugation to carbonyl, sulfonyl and phosphonate moieties, and epoxides. Deoxygenation of heteroaromatic N-oxides and deprotection of 1,3-dibenzyluracils have also been addressed.
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regio and stereoselective hydrogenation of conjugated carbonyl compounds via palladium assisted hydrogen transfer by Ammonium Formate
ChemInform, 1995Co-Authors: Brindaban C Ranu, Arunkanti SarkarAbstract:Abstract Excellent regio- and stereoselectivity has been achieved in the hydrogenation of CC bond conjugated to carbonyl group in presence of olefin by Ammonium Formate/Pd-C system.
Jeroen A Van Bokhoven - One of the best experts on this subject based on the ideXlab platform.
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promotion of Ammonium Formate and formic acid decomposition over au tio2 by support basicity under scr relevant conditions
ACS Catalysis, 2015Co-Authors: Manasa Sridhar, Jeroen A Van Bokhoven, Oliver Krocher, Martin Elsener, Davide FerriAbstract:This work demonstrates the rational design of a dedicated hydrolysis catalyst for application in the selective catalytic reduction (SCR) of NOx. Modification of titania by lanthanum prior to gold deposition entailed highly improved catalytic activities for Ammonium Formate (AmFo) and formic acid decomposition under SCR-relevant conditions stemming from dual phenomena: particle size effect and base effect. Smaller gold particles were stabilized, and there was higher uptake of CO2 and formic acid, as demonstrated by HAADF-STEM and in situ DRIFT analyses, respectively. The difference in the activities between the lanthanum-modified, unmodified, and tungsten-modified catalysts was implicitly dictated by the formic acid coverage, which was in turn greatly increased in the presence of base. In situ DRIFT studies under reaction conditions identified Formate as a relevant reaction intermediate, under reaction conditions. Higher E-a,E-app alongside a higher pre-exponential factor (A), describe an underlying compensation effect originating from the contribution of enthalpy associated with the desorption of the strongly adsorbed Formate, which is consistent with the highly negative formic acid orders observed in the case of the lanthanum-modified catalysts. Gold is essential to achieve selectivity to CO2; its absence yields CO. The introduction of lanthanum to the catalytic system preferentially promoted the CO2 formation mechanism, enabling complete decomposition of formic acid selectively to CO2 at significantly lower gold loading and lower contact times, making it a promising candidate for decomposition of Formate-based ammonia precursors in the SCR process.
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effect of ammonia on the decomposition of Ammonium Formate over au tio2 under oxidizing conditions relevant to scr enhancement of formic acid decomposition rate and co2 production
Applied Catalysis A-general, 2014Co-Authors: Manasa Sridhar, Jeroen A Van Bokhoven, Oliver KrocherAbstract:Ammonium Formate (AmFo) and formic acid decomposition were carried out in the presence of excess O-2 and H2O over 0.5 wt%Au/TiO2 anatase monolithic catalysts using various contact times and temperatures between 160 degrees C and 300 degrees C, under spray conditions in a dedicated setup. A systematic investigation of ammonia influence on formic acid decomposition revealed a highly beneficial influence on the reaction rate and the CO2 yield in the temperature range 160-300 degrees C. Ammonia oxidation did not occur at any of the studied temperatures and space velocities. Both AmFo and a stoichiometric ammonia formic acid mixture exhibited identical homogeneous gas phase as well as heterogeneous catalytic decomposition behavior. With the introduction of ammonia at a concentration of only 0.25 molar equivalents, the pseudo-first-order rate constants for formic acid decomposition experienced close to 110% and 15% increase at 160 degrees C and 260 degrees C, respectively and dosing 12 molar equivalents of ammonia in the gas phase, the rate constants underwent nearly 8-fold increase at 160 degrees C, while at 260 degrees C, only two times increase was achieved. Increasing the ammonia to formic acid molar ratio from 0 to 12 lead to a steep increase in the CO2 yield from 18% to 75% at 160 degrees C, while a relatively smaller rise from 60% to 75% was observed at 260 degrees C. Activity testing of bare titania revealed an inhibitory effect of ammonia on formic acid decomposition to CO. Overall, it can be concluded that the presence of gold is critical for the realization of such an ammonia-induced enhancement of rate and CO2 yield. The obtained results are relevant for the application of Formate-based ammonia precursor compounds in the selective catalytic reduction of NOx in Diesel exhaust gases. (C) 2014 Elsevier B.V. All rights reserved.
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Ammonium Formate decomposition over au tio2 a unique case of preferential selectivity against nh3 oxidation
Chemical Communications, 2014Co-Authors: Manasa Sridhar, Daniel Peitz, Jeroen A Van Bokhoven, Oliver KrocherAbstract:The unique selectivity of Au/TiO2 for converting Ammonium Formate to CO2 in the presence of excess O2 and H2O without oxidising NH3 up to 300 °C is reported. The catalyst is highly stable and selective even after severe hydrothermal aging.