Synergistic Syngas Production: Needleless Electrospinning Synthesis of Co/CeO2–La2O3 Catalyst for Efficient Dry Reforming of Methane

Posted on by
Synergistic Syngas Production: Needleless Electrospinning Synthesis of Co/CeO2–La2O3 Catalyst for Efficient Dry Reforming of Methane

The effect of catalyst morphology on the dry reforming of methane (DRM) was studied by comparing electrospun nanofibrous and impregnated Co-based supported catalysts. The former shows higher DRM activity, and its distinctive morphology plays a crucial role in stabilizing the Co particles through strong metal-support interaction, which significantly impedes catalyst deactivation by carbon deposition.


Abstract

The prime cause for catalyst deactivation during dry reforming of methane (DRM) has been attributed to the deposition of carbon. Nanofibrous (NF) catalysts are attractive candidates that offer high catalytic activity and stability in DRM. A comparative study between electrospun and impregnated Co/CeO2–La2O3 catalysts in the DRM reaction was carried out to evaluate the merits of the NF catalyst. Application of the electrospun catalyst yielded the highest activity in DRM and showed a substantial improvement in resistance to carbon formation. The unique structure of the NF electrospun catalyst, the robust metal-support interaction, and the increased surface area could more effectively suppress deactivation of the catalyst during an 8-h DRM reaction than the impregnated catalyst.

Monitoring Conformation and Protonation States of Glutathione by Raman Optical Activity and Molecular Dynamics

Posted on by
Monitoring Conformation and Protonation States of Glutathione by Raman Optical Activity and Molecular Dynamics

An analysis of Raman and Raman optical activity (ROA) spectra of glutathione based on computational modeling revealed that this peptide is flexible, but its conformation profile does not change significantly across a wide pH range. The adopted methodology could be appropriate for further structural studies of similar biomolecular systems.


Abstract

Glutathione (GSH) is a common antioxidant and its biological activity depends on the conformation and protonation state. We used molecular dynamics, Raman and Raman optical activity (ROA) spectroscopies to investigate GSH structural changes in a broad pH range. Factor analysis of the spectra provided protonation constants (2.05, 3.45, 8.62, 9.41) in good agreement with previously published values. Following the analysis, spectra of differently protonated forms were obtained by extrapolation. The complete deprotonation of the thiol group above pH 11 was clearly visible in the spectra; however, many spectral features did not change much with pH. Experimental spectra at various pH values were decomposed into the simulated ones, which allowed us to study the conformer populations and quality of molecular dynamics (MD). According to this combined ROA/MD analysis conformation of the GSH backbone is affected by the pH changes only in a limited way. The combination of ROA with the computations thus has the potential to improve the MD force field and obtain more accurate populations of the conformer species. The methodology can be used for any molecule, but for a more detailed insight better computational techniques are needed in the future.

Optimization of the Reaction Parameters of Immobilized Escherichia coli for β‐Cyclodextrin Production

Posted on by
Optimization of the Reaction Parameters of Immobilized Escherichia coli for β-Cyclodextrin Production

The effect of optimization of reaction parameters such as substrate concentration, temperature, and agitation rate of immobilized cells on β-cyclodextrin (β-CD) production and β-cyclodextrin glucanotransferase (β-CGTase) excretion was investigated. Both β-CD yield and CGTase excretion could be significantly improved, making the process more attractive for industrial applications.


Abstract

Cyclodextrin (CD) is an important substance for chemical, pharmaceutical, and food industries. Conventionally, free Escherichia coli (E. coli) cells expressing recombinant cyclodextrin glucanotransferase (CGTase) are used as the biocatalyst for CD production, but the process struggles with low CGTase excretion and CD yield. In this study, E. coli cells were immobilized on hollow-fiber membranes for β-CD production, and the process and reaction parameters were optimized via response surface methodology. The reusability of the immobilized cells was also evaluated. The parameter optimization significantly improved β-CD yield and CGTase excretion, making the process more attractive for industrial applications. The immobilized cells also revealed to be reusable multiple times.

Electrochemical Oxidation of Alcohols Using Halogen Mediators

Posted on by
Electrochemical Oxidation of Alcohols Using Halogen Mediators


Abstract

The high importance of carbonyl compounds in organic synthesis and fine chemical industries has let the development of efficient and environmentally benign methods for the oxidation of alcohols be an important research field. Electrochemistry would be one of the ideal strategies to achieve green redox processes avoiding the use of chemical oxidants/reductants. Due to the relatively high oxidation potential of alcohols, indirect methods using redox mediators have often been employed for the electrochemical alcohol oxidation. Halide salts would be one of the most traditional but still common mediators owing to the advantage of wide commercial availability and cost-efficiency. This review summarized the electrogenerated active halogen-mediated transformations of prim- sec-, and tert-alcohols from the pioneering works to the recent examples. In addition, recent advances in the direct oxidation of alcohols are also presented.