Indian Institute of Technology Ropar

About: Indian Institute of Technology Ropar is a education organization based out in Ropar, India. It is known for research contribution in the topics: Catalysis & Computer science. The organization has 1014 authors who have published 2878 publications receiving 35715 citations.

Highly efficient metal/solvent-free chemical fixation of CO2 at atmospheric pressure conditions using functionalized porous covalent organic frameworks

Abstract: The development of metal-free heterogeneous catalysts for selective carbon capture and utilization (CCU) as a C1-feedstock under mild conditions has significant potential towards sustainable fixation of atmospheric CO2 into value-added products. Herein, we report utilization of polar functionalized covalent-organic framework (COF-SO3H) as metal-free heterogeneous catalyst for efficient fixation of CO2 into cyclic carbonates. The COF-SO3H possesses large 1D channels functionalized with polar (–NH, and –SO3H) groups rendering selective adsorption property for CO2 with a high heat of interaction (Qst) energy of 42.2 kJ/mol. Interestingly, the value of Qst for COF-SO3H was found to be about 10.8 kJ/mol higher than that of analogous COF (COF-H) which lacks the polar sulfonic acid group. The presence of basic –NH sites combined with Bronsted acid (–SO3H) sites make COF-SO3H a suitable material for metal/solvent-free chemical fixation of CO2 with epoxides. Indeed, COF-SO3H catalyzes cycloaddition of CO2 with epoxides to generate cyclic carbonates under metal/solvent-free atmospheric pressure conditions. Moreover, COF-SO3H is highly recyclable for several cycles with retaining the catalytic activity and structural rigidity. This work represents a rare demonstration of metal/solvent-free chemical fixation of CO2 under atmospheric pressure conditions using polar-functionalized COF.

Bulk Viscosity at Extreme Limits: From Kinetic Theory to Strings

Abstract: In this paper we study bulk viscosity in a thermal QCD model with large number of colors at two extreme limits: the very weak and the very strong 't Hooft couplings. The weak coupling scenario is based on kinetic theory, and one may go to the very strong coupling dynamics via an intermediate coupling regime. Although the former has a clear description in terms of kinetic theory, the intermediate coupling regime, which uses lattice results, suffers from usual technical challenges that render an explicit determination of bulk viscosity somewhat difficult. On the other hand, the very strong 't Hooft coupling dynamics may be studied using string theories at both weak and strong string couplings using gravity duals in type IIB as well as M-theory respectively. In type IIB we provide the precise fluctuation modes of the metric in the gravity dual responsible for bulk viscosity, compute the speed of sound in the medium and analyze the ratio of the bulk to shear viscosities. In M-theory, where we uplift the type IIA mirror dual of the UV complete type IIB model, we study and compare both the bulk viscosity and the sound speed by analyzing the quasi-normal modes in the system at strong IIA string coupling. By deriving the spectral function, we show the consistency of our results both for the actual values of the parameters involved as well for the bound on the ratio of bulk to shear viscosities.

Double-Metal-Ion-Exchanged Mesoporous Zeolite as an Efficient Electrocatalyst for Alkaline Water Oxidation: Synergy between Ni–Cu and Their Contents in Catalytic Activity Enhancement

Abstract: The kinetics of total water splitting is mostly hampered by the sluggish oxygen evolution reaction (OER) at the anode of the electrolyzer. Herein, we focus on the design of a cost-effective porous OER catalyst for efficient water to fuel conversion. A simple metal-ion-exchange protocol is adapted to implant electroactive metal centers in the mesoporous architecture of Zeolite Socony Mobil-5 (ZSM-5). OER-active Ni is incorporated as catalytic sites in the mesoporous ZSM-5. Further, simultaneous incorporation of both Ni2+ and Cu2+ into the mesoporous ZSM-5 (Meso-Z) matrix significantly boost the OER catalytic activity. The optimization of Ni and Cu contents (1.04 wt % Ni and 0.44 wt % Cu) in the catalyst is found to be essential to achieve high catalytic activity. The Cu content influences the onset potential, and the Ni content determines the catalytic current during OER. Among developed catalysts, Ni2Cu1-Meso-Z offers the best performance even better than the state-of-art OER catalyst IrO2. Ni2Cu1-Meso-Z ...

Combined influences of viscous fingering and solvent effect on the distribution of adsorbed solutes in porous media

Abstract: The displacement of two fluids in a porous medium can be affected by a viscous fingering instability (VF) that arises at the interface between the fluids when their viscosities are different. In parallel, one of the fluids may contain solutes that reversibly adsorb on the porous matrix at a rate that depends on the composition of the two-fluid mixture, a so-called solvent strength effect. In some systems encountered for instance in liquid chromatographic columns or in underground flows in environmental applications, both VF and solvent strength effects may combine to influence the spatio-temporal distribution of solutes. Here, a computational investigation of such dynamics is performed. The distribution of the solute in the porous medium is affected by the combined effects of VF and solvent strength. A three component system (displacing fluid, sample solvent and solute) is modeled using Darcy's law for the fluid flow velocity coupled to a convection–diffusion equation for the sample solvent and a mass balance equation for the solute in the mobile and stationary phases. The sample solvent is assumed to have a larger solvent strength than the displacing fluid, in which the retention parameter due to the linear adsorption of the solute depends exponentially on the concentration of the sample solvent. A parametric study of the influences of the factors controlling the VF and solvent strength effects on the displacement velocity of the fronts of solute zone and on its width along the porous medium has been performed by direct numerical simulation of the governing equations. While each of the two effects (VF and solvent strength effects) distorts and significantly increases the broadening of the solute zone, the simulations reveal that, when they are acting in combination, these solute zone perturbations are reduced.

Sustainable Non-Noble Metal Bifunctional Catalyst for Oxygen-Depolarized Cathode and Cl2 Evolution in HCl Electrolysis

Abstract: The composite of polyoxometalate [WZn3(H2O)2(ZnW9O34)2]12– (ZnPOM) with polyvinylidene-butyl-imidazolium cation (PVIM) and oxidized carbon nanotubes (OCNT) as non-noble metal bifunctional catalyst has been studied for oxygen-depolarized cathode (ODC) and Cl2 evolution in HCl electrolysis for the first time. The cyclic voltammetry and rotating disk electrode measurement analysis reveals superior activity of the composite as bifunctional catalyst for ODC and Cl2 evolution. Chronoamperometric experiments show high long-term stability, comparable to the state-of-art catalyst, even under multiple shutdown to open circuit potential. X-ray photoelectron spectroscopic studies after electrolysis (48 h) confirms no degradation of the composite and, hence, appears to be stable. Scanning electrochemical microscopy (SECM) measurements indicate that, even after 72 h of electrolysis, the composite retains high activity, similar to fresh composite.