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Alkylene Oxides: Manufacture, Chemistry, and Applications
Published in F. E. Bailey, Joseph V. Koleske, Alkylene Oxides and Their Polymers, 2020
F. E. Bailey, Joseph V. Koleske
Propylene glycol has a very sizable usage because of its low toxicity. Unlike ethylene glycol, which is oxidized to oxalic acid, the oxidation products of propylene glycol form relatively soluble salts that are not harmful in quantities that are usually encountered. Propylene glycol is used widely in food, cosmetics, and drugs. In foods, it is used as a flavoring solvent and as a humectant in bread and baked goods; it is also used as an ink vehicle in packaging and as a packaging lubricant. It is also employed as a tobacco humectant and as a cosolvent in water-based surface coatings.
Humectants in Personal Care Formulation: A Practical Guide
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
Propylene glycol is the second most widely used humectant in personal care formulations. It is a three-carbon molecule with two hydroxyl groups. It is a clear, colorless, viscous liquid and, like glycerin, is miscible in water. The safety of propylene glycol is well known, and ingestion is harmless because in the body its oxidation results in metabolically useful pyruvic and acetic acids (10).
Polyalkylene Glycols
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
The initiator contains a labile hydrogen which in the presence of a catalyst chemically reacts with the oxide feed. Most initiators are alcohols. Examples include methanol, butanol, 2-ethylhexanol, and dodecanol. Glycols can also be used such as ethylene glycol, diethylene glycol, and propylene glycol. Triols and higher polyols are also used as initiators such as glycerol, trimethylolpropane, and pentaerythritol. However other initiator chemistries which contain labile hydrogens, such as thiols (-SH), organic acids (-COOH), amines, and alkanolamines (-NH-) have been used to develop PAGs. The functionality of the initiator, which is the number of labile hydrogen atoms that can be alkoxylated, can determine the polymer architecture. For example, monol initiated PAGs with a functionality of 1, such as those designed from butanol, lead to polymers that are hypothetically linear in structure. Conversely, triol initiated PAGs with a functionality of 3 lead to polymer structures which are branched. This feature can impart different rheology and tribology properties to the base oil.
A hydrometallurgical process for the recovery of metal values from spent Cu–Cr catalyst
Published in Mineral Processing and Extractive Metallurgy, 2018
J. Panigrahi, P.C. Rout, B. Garnaik, K. Sarangi
The catalysts are used in many chemical processes to enhance the rate of reaction with less energy consumption. The combination of cupric chromite and cupric oxide or Cu–Cr catalyst has been used for hydrogenation, dehydrogenation, hydrogenolysis and oxidation of carbon monoxide and hydrocarbon, etc. The Cu–Cr catalyst is used for hydrogen production by partial oxidation of methanol (Wang et al. 2003). The catalyst Cu60Cr40 exhibits high CH3OH conversion and H2 selectivity when compared with other binary catalysts. The hydrogenation of the furfural and levulinic acid to furfuryl alcohol and biofuel γ-valerolactone, respectively, was achieved using Cu–Cr catalyst (Yan & Chen 2013). Propylene glycol was manufactured by hydrogeneolysis of glycerol and in this process Cu:Zn:Cr:Zr-based catalyst was used (Sharma et al. 2014). Cu–Cr catalyst was also used for the oxidation of carbon monoxide (Xanthopoulou & Vekinis 1998).