Prakash D. Vaidya

Bio: Prakash D. Vaidya is an academic researcher from Institute of Chemical Technology. The author has contributed to research in topics: Catalysis & Steam reforming. The author has an hindex of 26, co-authored 94 publications receiving 3321 citations. Previous affiliations of Prakash D. Vaidya include University of Mumbai & University of Porto.

CO2‐Alkanolamine Reaction Kinetics: A Review of Recent Studies

Abstract: Alkanolamines are the most popular absorbents used to remove CO2 from process gas streams. Therefore, the CO2 reaction with alkanolamines is of considerable importance. The aim of this article is to provide an overview on the kinetics of the reaction of CO2 with aqueous solutions of alkanolamines. The various reaction mechanisms that are used to interpret experimental kinetic data – zwitterion, termolecular and base-catalyzed hydration – are discussed in detail. Recently published data on reaction kinetics of individual amine systems and their mixtures are considered. In addition, the kinetic behavior of several novel aminebased solvents that have been proposed in the literature is analyzed. Generally, the reaction of CO2 with primary, secondary and sterically hindered amines is governed by the zwitterion mechanism, whereas the reaction with tertiary amines is described by the base-catalyzed hydration of CO2.

Catalytic carbon dioxide hydrogenation to methanol: A review of recent studies

Abstract: Methanol demand is continuously increasing in the chemical and energy industries. It is commercially produced from synthesis gas (CO + CO 2 + H 2 ) using CuO/ZnO/Al 2 O 3 catalysts. Today, much effort is being put on the development of technologies for its production from carbon dioxide (CO 2 ). In this way, the Greenhouse effect may be mitigated. Over the years, several useful works on CO 2 hydrogenation to methanol have been reported in the literature. In this article, we present a comprehensive overview of all the recent studies published during the past decade. Various aspects on this reaction system (such as thermodynamic considerations, innovations in catalysts, influences of reaction variables, overall catalyst performance, reaction mechanism and kinetics, and recent technological advances) are described in detail. The major challenges confronting methanol production from CO 2 are considered. By now, such a discussion is still missing, and we intend to close this gap in this paper.

Glycerol Reforming for Hydrogen Production: A Review

Abstract: Glycerol, which is obtained as a by-product in biodiesel production, represents a candidate source of hydrogen that is renewable. Its conversion into hydrogen can be achieved by a reforming process. In this article, the glycerol reforming reaction is reviewed. Different reforming processes for hydrogen production, viz. steam, aqueous, and autothermal reforming, are described in brief. The thermodynamic analyses, which enable comparison with experimental studies, are considered. A discussion on experimental investigations over several catalysts is presented, too. Many reaction pathways are possible and some of them are dependent on the properties of the catalyst used. Generally, Ni, Pt, and Ru catalysts facilitate hydrogen production. The same catalysts are also effective for the reforming reaction of ethanol - another renewable resource for hydrogen. While ethanol steam reforming has been comprehensively reviewed by now, an overview on glycerol reforming is still missing. In this paper, an evaluation of the published studies is given to close this gap.

Kinetics of Steam Reforming of Ethanol over a Ru/Al2O3 Catalyst

Abstract: Catalytic steam reforming of ethanol over a Ru/γ-Al2O3 catalyst in the temperature range 873−973 K was studied. The influence of inlet ethanol concentration on ethanol conversion and hydrogen yield was investigated. The conversion vs space time data was subjected to the integral method of analysis. The results show that the reaction order with respect to ethanol is 1. An activation energy of 96 kJ mol-1 was obtained. A possible reaction sequence for ethanol steam reforming was suggested. A rate expression was derived assuming that the decomposition of an activated complex formed during reaction into intermediate products was the rate-determining step.

Carbon Dioxide Capture: Prospects for New Materials

Abstract: The escalating level of atmospheric carbon dioxide is one of the most pressing environmental concerns of our age. Carbon capture and storage (CCS) from large point sources such as power plants is one option for reducing anthropogenic CO(2) emissions; however, currently the capture alone will increase the energy requirements of a plant by 25-40%. This Review highlights the challenges for capture technologies which have the greatest likelihood of reducing CO(2) emissions to the atmosphere, namely postcombustion (predominantly CO(2)/N(2) separation), precombustion (CO(2)/H(2)) capture, and natural gas sweetening (CO(2)/CH(4)). The key factor which underlies significant advancements lies in improved materials that perform the separations. In this regard, the most recent developments and emerging concepts in CO(2) separations by solvent absorption, chemical and physical adsorption, and membranes, amongst others, will be discussed, with particular attention on progress in the burgeoning field of metal-organic frameworks.

Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles.

Abstract: Metal species with different size (single atoms, nanoclusters, and nanoparticles) show different catalytic behavior for various heterogeneous catalytic reactions. It has been shown in the literature that many factors including the particle size, shape, chemical composition, metal–support interaction, and metal–reactant/solvent interaction can have significant influences on the catalytic properties of metal catalysts. The recent developments of well-controlled synthesis methodologies and advanced characterization tools allow one to correlate the relationships at the molecular level. In this Review, the electronic and geometric structures of single atoms, nanoclusters, and nanoparticles will be discussed. Furthermore, we will summarize the catalytic applications of single atoms, nanoclusters, and nanoparticles for different types of reactions, including CO oxidation, selective oxidation, selective hydrogenation, organic reactions, electrocatalytic, and photocatalytic reactions. We will compare the results o...

Carbon capture and storage (CCS): the way forward

Abstract: Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, more recently, its ability to facilitate the net removal of CO2 from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO2 capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.

Progress and Perspectives of Electrochemical CO2 Reduction on Copper in Aqueous Electrolyte

Abstract: To date, copper is the only heterogeneous catalyst that has shown a propensity to produce valuable hydrocarbons and alcohols, such as ethylene and ethanol, from electrochemical CO2 reduction (CO2R). There are variety of factors that impact CO2R activity and selectivity, including the catalyst surface structure, morphology, composition, the choice of electrolyte ions and pH, and the electrochemical cell design. Many of these factors are often intertwined, which can complicate catalyst discovery and design efforts. Here we take a broad and historical view of these different aspects and their complex interplay in CO2R catalysis on Cu, with the purpose of providing new insights, critical evaluations, and guidance to the field with regard to research directions and best practices. First, we describe the various experimental probes and complementary theoretical methods that have been used to discern the mechanisms by which products are formed, and next we present our current understanding of the complex reaction networks for CO2R on Cu. We then analyze two key methods that have been used in attempts to alter the activity and selectivity of Cu: nanostructuring and the formation of bimetallic electrodes. Finally, we offer some perspectives on the future outlook for electrochemical CO2R.