: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

https://chemical.eng.usm.my/bassim/PDF/photocatalytic%20degradation.pdf

Parameters affecting the photocatalytic degradation of dyes using TiO2-based photocatalysts: a review.

Rapidly increasing atmospheric CO2 concentrations threaten human society, the natural environment, and the synergy between the two. In order to ameliorate the CO2 problem, carbon capture and conversion techniques have been proposed. Metal–organic framework (MOF)-based materials, a relatively new class of porous materials with unique structural features, high surface areas, chemical tunability and stability, have been extensively studied with respect to their applicability to such techniques. Recently, it has become apparent that the CO2 capture capabilities of MOF-based materials significantly boost their potential toward CO2 conversion. Furthermore, MOF-based materials’ well-defined structures greatly facilitate the understanding of structure–property relationships and their roles in CO2 capture and conversion. In this review, we provide a comprehensive account of significant progress in the design and synthesis of MOF-based materials, including MOFs, MOF composites and MOF derivatives, and their application to carbon capture and conversion. Special emphases on the relationships between CO2 capture capacities of MOF-based materials and their catalytic CO2 conversion performances are discussed.

Carbon capture and conversion using metal–organic frameworks and MOF-based materials

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...

Sustainable Conversion of Carbon Dioxide: An Integrated Review of Catalysis and Life Cycle Assessment

It is well known that urbanization and industrialization have resulted in the rapidly increasing emissions of volatile organic compounds (VOCs), which are a major contributor to the formation of secondary pollutants (e.g., tropospheric ozone, PAN (peroxyacetyl nitrate), and secondary organic aerosols) and photochemical smog. The emission of these pollutants has led to a large decline in air quality in numerous regions around the world, which has ultimately led to concerns regarding their impact on human health and general well-being. Catalytic oxidation is regarded as one of the most promising strategies for VOC removal from industrial waste streams. This Review systematically documents the progresses and developments made in the understanding and design of heterogeneous catalysts for VOC oxidation over the past two decades. It addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions. It also highlights the primary routes for catalyst deactivation and discusses protocols for their subsequent reactivation. Kinetic models and proposed oxidation mechanisms for representative VOCs are also provided. Typical catalytic reactors and oxidizers for industrial VOC destruction are further discussed. We believe that this Review will provide a great foundation and reference point for future design and development in this field.

/pdf/recent-advances-in-the-catalytic-oxidation-of-volatile-zw2c35dbg7.pdf

Recent Advances in the Catalytic Oxidation of Volatile Organic Compounds: A Review Based on Pollutant Sorts and Sources.

A simple and efficient route for one-pot synthesis of high-molecular-weight aliphatic polycarbonates (APCs) by direct melt transesterification of diphenyl carbonate (DPC) with aliphatic diols at equimolar amounts was developed. Zn(OAc)2 was found to be the best catalyst for this reaction among the screened transition metal acetates. The effects of reaction conditions on Mw and yield of the poly(1,4-butylene carbonate) (PBC) were investigated, where the highest Mw of 156200 g mol−1 with a yield of 83% was obtained under suitable reaction conditions. In addition, based on the results of thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), a plausible reaction mechanism over Zn(OAc)2 was proposed for APC synthesis.

One-pot synthesis of high-molecular-weight aliphatic polycarbonates via melt transesterification of diphenyl carbonate and diols using Zn(OAc)2 as a catalyst

Novel catalytic systems containing n -butylstannonic acid ( n -BuSn(O)OH) were used to synthesize methyl phenyl carbonate (MPC) and diphenyl carbonate (DPC) by the transesterification of dimethyl carbonate (DMC) with phenol in atmospheric conditions. The catalytic system consisting of n -BuSn(O)OH and cuprous iodide (CuI) had the highest activity for the transesterification. When the reaction was carried out between 150 and 180 °C, with a molar ratio of n -BuSn(O)OH to CuI of 1:1, a catalyst amount 0.005 (molar ratio to DMC), a reaction time 10 h, a molar ratio of DMC to phenol of 2:1, a dropping time of DMC 6 h, the conversion of phenol was 67.2%, and the selectivity of MPC and DPC was 40.2 and 59.6%, respectively. Upon comparison of the activities of Cu 2 O, CuX (X = Cl, Br, I) and the catalytic system being composed of n -BuSn(O)OH and Cu 2 O/CuX, it was found that Cu 2 O and CuX were excellent promoters, and the stronger was the anion electronegativity in the promoter, the weaker was the promoting catalysis of the promoter.

Novel catalytic systems containing n-BuSn(O)OH for the transesterification of dimethyl carbonate and phenol

The adsorption of carboxymethyl starch (CMS) at the α-alumina/aqueous solution interface has been investigated through adsorption studies, electrokinetics mobility measurements, and FTIR spectroscopy. Zeta potential measurements show that the addition of CMS results in a more dramatic increase in the absolute zeta potential in the alkaline region, as well as a shift of the isoelectric point to lower values, indicating the adsorption of CMS from the aqueous solution onto the alumina surface. The positive hydrophilic surface sites of alumina are responsible for the adsorption of CMS molecules. The adsorption of CMS is possible after charge reversal by the addition of excess CMS. Nearly 30 min of contact time are found to be sufficient for the adsorption of CMS to reach equilibrium. CMS adsorption follows a Langmuir isotherm with adsorption capacities of 91.74 mg CMS per gram of α-alumina. For the adsorption of CMS, pseudo-second-order chemical reaction kinetics provides the best correlation with the experimental data. FTIR analysis indicated that CMS forms outer complexes with alumina surfaces depending on the shifting of the asymmetric and symmetric bands.

Kinetics and adsorption behavior of carboxymethyl starch on α-alumina in aqueous medium

The photodegradation of bisphenol S (BPS) in aqueous solutions was studied under different conditions. Photolysis and kinetics were investigated, as were the photolysis mechanism and the influences of initial pH value, light source, and environmental substances in water. The results showed that the photolysis of BPS occurred under UV light, and the rate increased with light source intensity. The photolysis of 5.0–50.0 mg/L BPS in water followed first-order kinetics: the rate was γ = 0.0161C BPS under a 40-W UV-lamp, and the degradation half-life was 43.1 min. Due to its absorption of light, direct photolysis of BPS was a predominant pathway for BPS but was not obviously affected by reactive oxygen species. The results confirmed that the photolysis rates of BPS in alkaline water solution were faster than those in acidic and neutral water solution because of the ionization of BPS. The photodegradation rate of BPS increased in the presence of chloride and ferric ions, while the rate was inhibited by nitrate and phosphate in aqueous solution.

Gongying Wang

Papers

One-pot synthesis of high-molecular-weight aliphatic polycarbonates via melt transesterification of diphenyl carbonate and diols using Zn(OAc)2 as a catalyst

Novel catalytic systems containing n-BuSn(O)OH for the transesterification of dimethyl carbonate and phenol

Kinetics and adsorption behavior of carboxymethyl starch on α-alumina in aqueous medium

Photolysis kinetics and influencing factors of bisphenol S in aqueous solutions.

The transesterification of dimethyl carbonate and phenol catalyzed by 12-molybdophosphoric salts