Bio: Sounak Roy is an academic researcher from Birla Institute of Technology and Science. The author has contributed to research in topics: Catalysis & Photocatalysis. The author has an hindex of 23, co-authored 66 publications receiving 2755 citations. Previous affiliations of Sounak Roy include ETH Zurich & Indian Institute of Science.
Papers published on a yearly basis
TL;DR: In this paper, the main portion of the review discusses the progress and development of various catalysts for NOx removal from exhaust by NO decomposition, NO reduction by CO or H-2 or NH3 or hydrocarbons.
Abstract: Research in the field of NOx abatement has grown significantly in the past two decades. The general trend has been to develop new catalysts with complex materials in order to meet the stringent environmental regulations. This review discusses briefly about the different sources of NOx and its adverse effect on the ecosystem. The main portion of the review discusses the progress and development of various catalysts for NOx removal from exhaust by NO decomposition, NO reduction by CO or H-2 or NH3 or hydrocarbons. The importance of understanding the mechanism of NO decomposition and reduction in presence of metal ion substituted catalysts is emphasized. Some conclusions are made on the various catalytic approaches to NOx abatement.
TL;DR: Theoretical and Surface Science Studies Studies 4079 6.1.
Abstract: 4.1. Noble Metals 4058 4.1.1. Platinum 4059 4.1.2. Palladium 4060 4.1.3. Bimetallic Systems 4060 4.2. Storage Components 4061 4.2.1. Earth Alkaline Metals 4061 4.2.2. Alkali Metals 4065 4.3. Supports 4065 4.3.1. Single Oxides 4065 4.3.2. Mixed Oxides 4067 4.4. Promoters 4069 4.5. Preparation Methods 4071 4.6. Influence of Remote Control 4073 5. Influence of Exhaust Gas Composition 4074 5.1. Reducing Gas 4074 5.2. Water 4077 5.3. Carbon Dioxide 4077 5.4. Impact of Soot 4079 6. Theoretical and Surface Science Studies 4079 6.1. Theoretical Studies 4079 6.2. Studies on Well-Defined Model Catalysts 4082 7. Reactor Configuration 4082 8. Conclusions and Outlook 4086 9. Acknowledgments 4087 10. References 4087
TL;DR: In this article, a selective catalytic reduction (SCR) of NO with NH3 was investigated over these catalysts, and the reaction occurred at low temperature with a high selectivity over this catalyst.
Abstract: The catalysts, Ti0.9M0.1O2-δ (M = Cr, Mn, Fe, Co, Cu), were synthesized in anatase phase by solution combustion. Selective catalytic reduction (SCR) of NO with NH3 was investigated over these catalysts. The reaction occurred at the lowest temperature over Ti0.9Mn0.1O2-δ, but the selectivity for N2 was highest over Ti0.9Fe0.1O2-δ. Therefore, both Mn and Fe were substituted in TiO2 (Ti0.9Mn0.05Fe0.05O2-δ). The reaction occurred at low temperature with a high selectivity over this catalyst. In order to understand the reaction mechanism and the nature of the active sites, temperature programmed desorption (TPD) of NH3 and hydrogen uptake studies were carried out. The relation between the Lewis acid sites and SCR window and the relation between Bronsted acid sites and low temperature was established. The order of the SCR reaction with respect to NO, NH3, and O2 was also investigated. It was also shown that the N2 selectivity of the SCR reaction has a strong inverse correlation with the oxidation of ammonia.
TL;DR: In this paper, the acid sites on γ-Al2O3 were characterized using FTIR spectroscopy of adsorbed pyridine and temperature programmed desorption (TPD) of 2-propanamine, ethanol, 1-Propanol, 2-methyl-2propanol.
Abstract: The acid sites on γ-Al2O3 were characterized using FTIR spectroscopy of adsorbed pyridine and temperature programmed desorption (TPD) of 2-propanamine, ethanol, 1-propanol, 2-propanol, and 2-methyl-2-propanol, together with density functional theory (DFT) calculations. Following room-temperature adsorption and evacuation, the surface coverages of the adsorbed alcohols were between 2 and 3.2 × 1018 molecules/m2. For each of the adsorbed alcohols, reaction to olefin and water products occurred in a narrow peak that indicated reaction is a first-order process with a well-defined activation energy, which in turn depended strongly on the particular alcohol. DFT calculations on an Al8O12 cluster are in excellent agreement with the experimental observations and show that the transition states for dehydration had carbenium-ion character. The carbenium ion stability in terms of proton affinity (of alkenes) matches well with the activation energy of the dehydration reaction. Adsorption of water on the γ-Al2O3, foll...
TL;DR: In this work, the phase pure anatase and rutile TiO2 have been explored for photocatalytic nitroarenes reduction to understand the role of surface structures and band alignment towards the reduction mechanism.
Abstract: It is a subject of exploration whether the phase pure anatase or rutile TiO2 or the band alignment due to the heterojunctions in the two polymorphs of TiO2 plays the determining role in efficacy of a photocatalytic reaction. In this work, the phase pure anatase and rutile TiO2 have been explored for photocatalytic nitroarenes reduction to understand the role of surface structures and band alignment towards the reduction mechanism. The conduction band of synthesized anatase TiO2 has been found to be more populated with electrons of higher energy than that of synthesized rutile. This has given the anatase an edge towards photocatalytic reduction of nitroarenes over rutile TiO2. The other factors like adsorption of the reactants and the proton generation did not play any decisive role in catalytic efficacy.
TL;DR: The motivation to develop CO2-based chemistry does not depend primarily on the absolute amount of CO2 emissions that can be remediated by a single technology and is stimulated by the significance of the relative improvement in carbon balance and other critical factors defining the environmental impact of chemical production in all relevant sectors in accord with the principles of green chemistry.
Abstract: CO2 conversion covers a wide range of possible application areas from fuels to bulk and commodity chemicals and even to specialty products with biological activity such as pharmaceuticals. In the present review, we discuss selected examples in these areas in a combined analysis of the state-of-the-art of synthetic methodologies and processes with their life cycle assessment. Thereby, we attempted to assess the potential to reduce the environmental footprint in these application fields relative to the current petrochemical value chain. This analysis and discussion differs significantly from a viewpoint on CO2 utilization as a measure for global CO2 mitigation. Whereas the latter focuses on reducing the end-of-pipe problem “CO2 emissions” from todays’ industries, the approach taken here tries to identify opportunities by exploiting a novel feedstock that avoids the utilization of fossil resource in transition toward more sustainable future production. Thus, the motivation to develop CO2-based chemistry does...
TL;DR: In this paper, the recent developments and trends in combustion science towards the synthesis of nanomaterials are discussed, and different modifications made to conventional combustion approaches for preparation of nano-materials are critically analyzed.
Abstract: The recent developments and trends in combustion science towards the synthesis of nanomaterials are discussed. Different modifications made to conventional combustion approaches for preparation of nanomaterials are critically analyzed. Special attention is paid to various applications of combustion synthesized nanosized products.
TL;DR: This Review focuses on the analysis of new approaches and results in the field of solution combustion synthesis (SCS) obtained during recent years, emphasizing the chemical mechanisms that are responsible for rapid self-sustained combustion reactions.
Abstract: Solution combustion is an exciting phenomenon, which involves propagation of self-sustained exothermic reactions along an aqueous or sol–gel media. This process allows for the synthesis of a variety of nanoscale materials, including oxides, metals, alloys, and sulfides. This Review focuses on the analysis of new approaches and results in the field of solution combustion synthesis (SCS) obtained during recent years. Thermodynamics and kinetics of reactive solutions used in different chemical routes are considered, and the role of process parameters is discussed, emphasizing the chemical mechanisms that are responsible for rapid self-sustained combustion reactions. The basic principles for controlling the composition, structure, and nanostructure of SCS products, and routes to regulate the size and morphology of the nanoscale materials are also reviewed. Recently developed systems that lead to the formation of novel materials and unique structures (e.g., thin films and two-dimensional crystals) with unusual...
TL;DR: This review summarizes the latest SCR reaction mechanisms and emerging poison-resistant mechanisms in the beginning and subsequently gives a comprehensive overview of newly developed SCR catalysts, including metal oxide catalysts ranging from VOx, MnOx, CeO2, and Fe2O3 to CuO based catalysts.
Abstract: Selective catalytic reduction with NH3 (NH3-SCR) is the most efficient technology to reduce the emission of nitrogen oxides (NOx) from coal-fired industries, diesel engines, etc. Although V2O5-WO3(MoO3)/TiO2 and CHA structured zeolite catalysts have been utilized in commercial applications, the increasing requirements for broad working temperature window, strong SO2/alkali/heavy metal-resistance, and high hydrothermal stability have stimulated the development of new-type NH3-SCR catalysts. This review summarizes the latest SCR reaction mechanisms and emerging poison-resistant mechanisms in the beginning and subsequently gives a comprehensive overview of newly developed SCR catalysts, including metal oxide catalysts ranging from VOx, MnOx, CeO2, and Fe2O3 to CuO based catalysts; acidic compound catalysts containing vanadate, phosphate and sulfate catalysts; ion exchanged zeolite catalysts such as Fe, Cu, Mn, etc. exchanged zeolite catalysts; monolith catalysts including extruded, washcoated, and metal-mesh/foam-based monolith catalysts. The challenges and opportunities for each type of catalysts are proposed while the effective strategies are summarized for enhancing the acidity/redox circle and poison-resistance through modification, creating novel nanostructures, exposing specific crystalline planes, constructing protective/sacrificial sites, etc. Some suggestions are given about future research directions that efforts should be made in. Hopefully, this review can bridge the gap between newly developed catalysts and practical requirements to realize their commercial applications in the near future.
TL;DR: The main focus is put on NO(x) control methods applied in combustion of fossil fuels in power stations and mobile vehicles, as well as methods used in chemical industry, where the implementation of ozone and other oxidizing agents in NO (x) oxidation is emphasized.
Abstract: Implementation of stringent regulations of NO(x) emission requires the development of new technologies for NO(x) removal from exhaust gases. This article summarizes current state of NO(x) abatement strategy. Firstly, the influence of NO(x) on environment and human health is described. The main focus is put on NO(x) control methods applied in combustion of fossil fuels in power stations and mobile vehicles, as well as methods used in chemical industry. Furthermore the implementation of ozone and other oxidizing agents in NO(x) oxidation is emphasized.