Cu/O Frustrated Lewis Pairs on Cu Doped CeO2(111) for Acetylene Hydrogenation: A First-Principles Study

In this work, the H2 dissociation and acetylene hydrogenation on Cu doped CeO2(111) were studied using density functional theory calculations. The results indicated that Cu doping promotes the formation of oxygen vacancy (Ov) which creates Cu/O and Ce/O frustrated Lewis pairs (FLPs). With the help of Cu/O FLP, H2 dissociation can firstly proceed via a heterolytic mechanism to produce Cu-H and O-H by overcoming a barrier of 0.40 eV. The H on Cu can facilely migrate to a nearby oxygen to form another O-H species with a barrier of 0.43 eV. The rate-determining barrier is lower than that for homolytic dissociation of H2 which produces two O-H species. C2H2 hydrogenation can proceed with a rate-determining barrier of 1.00 eV at the presence of Cu-H and O-H species., While C2H2 can be catalyzed by two O-H groups with a rate-determining barrier of 1.06 eV, which is significantly lower than that (2.86 eV) of C2H2 hydrogenated by O-H groups on the bare CeO2(111), showing the high activity of Cu doped CeO2(111) for acetylene hydrogenation. In addition, the rate-determining barrier of C2H4 further hydrogenated by two O-H groups is 1.53 eV, much higher than its desorption energy (0.72 eV), suggesting the high selectivity of Cu doped CeO2(111) for C2H2 partial hydrogenation. This provides new insights to develop effective hydrogenation catalysts based on metal oxide.

THE BOUILLON TABLES FROM TURKEY: DETERMINATON OF CIS-TRANS FATTY ACID PROFILES BY CAPILLARY GAS CHROMATOGRAPHY

Nowadays, commmercial bouillon tablets are mostly used as a flavor enhancer substant or an instant product in Turkish cuisine. As chemical structure, Trans FAs are unsaturated fatty acids having at least one double bond in its trans geometric configuration. Trans FA are occured by the partial hydrogenation of vegetable oils in the manufacturing of margarine and vegetable shortening. In this study, industrially produced commmercial bouillon tablet (n=14) samples from Turkey were analyzed by capillary (DB 23 column) gas chromatography method and an under controlled temperature oven programm with particular emphasis on cis–trans fatty acid profiles. The bouillon samples were collected as two goups (first group containing animal additives [AAB n=12] and second group including vegatable additives [VAB n=2]). There is no detailed information on fatty acid (FA) compounds, including trans fatty acids (TFAs), of consumed several commercial boullions in Turkey. There is no “trans fatty acid-free” declaration on various bouillon labels in Turkey. Large variations were observed among the cis–trans FA profiles of the boullion samples from Turkey,despite the fact that the samples are produced in the same production conditions.The palmitic (PAM) levels (predominant cis saturated FAs for all samples) of AAB samples (32.63–44.44%) were more high rather than the VAB samples (47.62–50.64%). Other major saturated FAs for AAB and VAB samples were determined stearic ( (5.28–9.90% AAB and 6.33–6.73% VAB), lauric (0.19– 5.84% AAB and 1.13–1.30% VAB) and myristic acids (0.86–2.61% AAB and 1.39–1.45% VAB).The changes of oleic (OLA) acid (from other predominant cis monounsaturated FA) of VAB samples (30.75–33.45%) were high than those of AABs (12.64–29.35%). The ranges of LO, an essential /nutritional fatty acid and the predominant FA of PUFAs, and PUFAs of AAB – except two samples– commercial bouillon samples (0.45–9.82% and 0.45–9.97% ) were low rather than VAA samples (7.97–8.14% and 8.14–8.35 %). Conjugated Linoleic (CLA) FAs, having nutritional FAs having anti-carcinogenic, antioxidative and anti-atherosclerotic effects, were determined in small amounts for only six samples (0.03% to 0.06% ). Elaidic acid (C18:1 trans acid) content, the mainly trans FA in all boullion, was within the range of 20.00–27.32% in the AAB samples, and it was significantly higher than the range in VAB samples (0.08–0.14%). Total trans fatty acids (TFAs) were another important major (second) FAs for all bouillon samples. The changes of Trans/Cis ratio ranged between 0.26 and 0.50 for AAB samples but VB samples has a little values from 0.002 to 0.003. Turkish vegetable boullion. samples have low total trans FA contents (0.19–0.26%) than the animal boullion samples (20.19–28.78%).There are a large variation and significant (P<0.05) differences were statistically determined among major cis FAs (PAM, SA, OLA, LO and LN) and their involved parameters (SFAs, MUFAs and PUFAs). The consumed several commercial boullions in Turkey were classified and characterized chemometric method (Principal Component Analysis, PCA) based on some fatty acid profiles and their parameters. Applying PCA to the all bouillon samples data determined the percentage of total variance explained by the first two PCs were 49.3% and 21.8% (totally 71.1%), respectively.

Low-temperature and atmospheric pressure plasma for palm biodiesel hydrogenation

Partially hydrogenated fatty acid methyl ester (H-FAME) is conventionally produced through partial hydrogenation under high pressure and elevated temperature in the presence of a catalyst. Herein, a novel green, catalyst-free, non-thermal and atmospheric pressure dielectric barrier discharge (DBD) plasma was employed instead of a conventional method to hydrogenate palm FAME. H-FAME became more saturated with the conversion of C18:2 and C18:3 of 47.4 and 100%, respectively, at 100 W input power, 1 mm gas-filled gap size and 80% H2 in the mixed gas at room temperature for 5 h, causing a reduction of the iodine value from 50.2 to 43.5. Oxidation stability increased from 12.8 to 20 h while a cloud point changed from 13.5 to 16 °C. Interestingly, DBD plasma hydrogenation resulted in no trans-fatty acid formation which provided a positive effect on the cloud point. This green DBD plasma system showed a superior performance to a conventional catalytic reaction. It is an alternative method that is safe from explosion due to the mild operating condition, as well as being highly environmentally friendly by reducing waste and energy utilization from the regeneration process required for a catalytic process. This novel green plasma hydrogenation technique could also be applied to other liquid-based processes.