This work deals with kinetics and chemical equilibrium studies of esterification reaction of ethanol with acetic acid.  The esterification reaction was catalyzed by an acidic ion exchange resin (Amberlyst-15) using a batch stirred tank reactor. The pseudo-homogenous and Eley-Rideal models were successfully fitted with experimental data. At first, Eley-Rideal model was examined for heterogeneous...

The extensive demand for cleaner environment is forcing the chemical industry to use less hazardous materials. In this regard, solid catalysts have lately attracted the attention of scientists and researchers around the world.1–8 By using sufficient amounts of these heterogeneous catalysts, their catalytic activity for ester formation can be equivalent to that of conventional homogeneous cataly...

Choline dihydrogen phosphate has previously been shown to be a good ionic conductor as well as an excellent host for acid doping, leading to high proton conductivities required for e.g., electrochemical devices including proton membrane fuel cells and sensors. A combination of variable-temperature (1)H solid-state NMR and 2D NMR pulse sequences, including (31)P and (13)C CODEX and (1)H BaBa, sh...

NMR spectroscopy was used to characterize the dynamic behavior of His149 in Bacillus circulans xylanase (BCX) and its interaction with an internal water molecule. Rate constants for the specific acid- and base-catalyzed exchange following bimolecular kinetics (EX2) of the nitrogen-bonded H epsilon 2 of this buried, neutral histidine were determined. At pDmin 7.0 and 30 degrees C, the lifetime f...

13C-NMR has been used to follow the tryptophan synthase (EC 4.2.1.20) catalysed hydrogen-deuterium exchange of the pro-2R and pro-2S protons of [2-13C]glycine at pH 7.8. 1H-NMR has also been used to follow the tryptophan-synthase-catalysed hydrogen-deuterium exchange of the alpha-protons of a range of L- and D-amino acids at pH 7.8. The pK(a) values of the alpha-protons of these amino acids hav...

The structural specificity of amine oxidation by lysyl oxidase was investigated using kinetic and NMR spectroscopic analyses. Substrate efficiency increased with increasing molecular distance from the alpha-carbon of the aromatic moiety substituted on the aliphatic chains of a series of primary amines. The p-hydroxyl substituent of p-hydroxybenzylamine significantly increased kcat over that of ...

Water loss and the coincident increase in membrane resistance to proton conduction are significant barriers to high performance operation of traditional proton exchange membrane fuel cells at elevated temperatures where the relative humidity may be reduced. We report here approaches to the development of high temperature membranes for proton exchange membrane fuel cells; composite perfluorinate...

Fuel cells hold great promise for wide applications in portable, residential, and large-scale power supplies. For low temperature fuel cells, such as the proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs), proton-exchange membranes (PEMs) are a key component determining the fuel cells performance. PEMs with high proton conductivity under anhydrous conditions can...