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In a solvent extraction screening study, several β-branched alcohols in the 14–20 carbons range show improved extractive performance to recover ethanol from aqueous solutions compared to commonly studied solvents such as oleyl alcohol and 1-dodecanol. These β-branched alcohols were selected for screening based on extrapolation of results in earlier work with lower molecular weight aliphatic alcohol solvents, that indicated higher separation factors should be realized when hydroxyl position is mid-chain, and there is branching. Solvent toxicity to a commercial yeast commonly used in fuel ethanol production also was evaluated for these as well as several lower molecular weight alcohols. For the alcohols studied, those containing 12 or fewer carbons were toxic or inhibitory to the yeast; those containing 14 or more carbons were non-toxic and non-inhibitory.

The prevalence of optical spectroscopy techniques being applied to the online analysis of continuous processes has increased in the past couple of decades. The ability to continuously “watch” changing stream compositions as operating conditions change has proven invaluable to pilot and world-scale manufacturing in the chemical and petrochemical industries. Presented here is an application requiring continuous monitoring of parts per million (ppm) by weight levels of hydrogen chloride (HCl), water (H2O), and carbon dioxide (CO2) in two gas-phase streams, one nitrogen-rich and one ethylene-rich. Because ethylene has strong mid-infrared (IR) absorption, building an IR method capable of quantifying HCl, H2O, and CO2 posed some challenges. A long-path (5.11m) Fourier transform infrared (FT-IR) spectrometer was used in the mid-infrared region between 1800 and 5000 cm−1, with a 1 cm−1 resolution and a 10 s spectral update time. Sample cell temperature and pressure were controlled and measured to minimize measurement variability. Models using a modified classical least squares method were developed and validated first in the laboratory and then using the process stream. Analytical models and process sampling conditions were adjusted to minimize interference of ethylene in the ethylene-rich stream. The predictive capabilities of the measurements were ±0.5 ppm for CO2 in either stream; ±1.1 and ±1.3 ppm for H2O in the nitrogen-rich and ethylene-rich streams, respectively; and ±1.0 and ±2.4 ppm for HCl in the nitrogen-rich and ethylene-rich streams, respectively. Continuous operation of the instrument in the process stream was demonstrated using an automated stream switching sample system set to 10 min intervals. Response time for all components of interest was sufficient to acquire representative stream composition data. This setup provides useful insight into the process for troubleshooting and optimizing plant operating conditions.

Online analyzers enable manufacturers to operate modern polymerization processes as safely, reliably, and profitably as possible. The most critical application of this technology involves monitoring the reactor itself to determine the molecular weight and comonomer content of the polymer produced. Polymer process streams introduce unique challenges for online analyzers because the process chemistry, sample transport, and stream conditions are harsher, prone to fouling, and pose unique safety hazards. Spectroscopy lends itself very well to online analysis of polymers because the data it provides is information rich and can be deployed using fiber optics for remote sampling of gases, liquids, and solids. Additionally, it is relatively fast and reliable if well designed and installed properly. The combination of spectroscopy, fiber optics, and chemometrics gives manufacturers the ability to use modern spectrometers and statistical models to analyze and monitor diverse types of polymerization processes. Several examples are provided in this article, including application to polyethylene, polycarbonate, polyurethane, and polystyrene processes.