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T < 1000 K)
Published in J. F. Griffiths, J. A. Barnard, Flame and Combustion, 2019
J. F. Griffiths, J. A. Barnard
The low temperature oxidation of organic compounds involves a considerable variety of reactive intermediates and there is a correspondingly large number of molecular products. There is a coherent structure to the elementary reactions involved, which can be coordinated in a formal structure for the kinetics. ‘Higher alkanes’ refers essentially to the series starting with normal butane and isobutane. There is a limited overlap with the behaviour of propane. The main, gaseous reaction pathways spanning the temperature range of approximately 500–850 K are encapsulated in Fig. 7.1, taking butane as a representative case. A number of simplifications are made to maintain clarity.
Recovery utilization of triolein for producing short chain alkane by combining biocatalysis and inorganic catalysis
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Jie Zhang, Ling Gao, Yao Lu, Lixiu Yan, Xuemei Tan, Zhehan Yang, Huijun Zhang
In Figure 4a, we can observe that the highest yield of octane was detected as 30.9% for 0.25 h. However, the yield of octane decreased with time, until octane cannot be detected after 12 h. Interestingly, Huijbers, Zhang (Huijbers et al. 2018) reported that several fatty acids were converted by CvFAP in near-quantitative yield and exclusive selectivity upon illumination with blue light, the conversion of lauric acid (C12H24O2), stearic acid (C18H36O2) and oleic acid (C18H34O2) were 11%, 92%, and 65% after 14 h, respectively. It is speculated that the decarboxylation reaction of fatty acids was carried out in the access channel of the decarboxylase, and long-chain alkanes have good stability in the access channel of decarboxylase (Sorigué et al. 2017). However, the results show that short-chain fatty acid have higher alkane yields in a short time (0.25 h), and this optimal activity time is shorter than reported. Different catalytic activity time may be caused by different chain length. It is inferred that shorter chain fatty acids are more likely to enter access channel of the decarboxylase for decarboxylation. But, amounts of cumulated alkanes probably formed dimers due to the activation of terminal C-H bonds by decarboxylase. Therefore, the production of objective product decrease with the increase of reaction time, while the stable long chain fatty acids will not, which is in accord with the current research results.
Decarboxylation of oleic acid using iridium catalysis to form products of increased aromatic content compared to ruthenium systems
Published in International Journal of Sustainable Engineering, 2021
Kenneth M. Doll, Bryan R. Moser, Gerhard Knothe
The reaction (Scheme 1) requires dehydrogenation to occur in order to form aromatic products. The natural consequence of the presence of this hydrogen is the conversion of some of the substrate or unsaturated product into saturated materials. Thus, higher production of aromatics, leading to increased liberation of hydrogen, should correlate with higher alkane content. This relationship was demonstrated at 250°C when higher aromatic and alkane contents (37% and 6.2%, respectively) were obtained relative to similar reactions conducted at 200°C (19% and <1%, respectively). Other factors are interesting here as well. There is some ambiguity regarding the homogeneous vs heterogeneous nature of the catalyst. It is possible that the liberated hydrogen is changing the highly reducible iridium metal, especially in this heated and pressurised environment. This could also explain the difference between the Ir+1 and Ir0 precatalyst species.
Physicochemical characteristics, antioxidant capacity and thermodynamic properties of purple-fleshed potatos dried by radio frequency energy
Published in Drying Technology, 2020
Min Gou, Yuxiang Gu, Wenhao Li, Jianmei Zheng, Hao Jiang
The relative content of volatile materials determined by headspace solid phase microextraction are presented in Table 6. The heating/drying process produces a range of flavor-active volatile aromatics due to auto-oxidation, enzymic action on hydroperoxides, and Maillard reactions.[47] Among them, alkanes and esters were the primary flavor substances. The area percentage of alkanes, amines, aromatic and esters were 1.42, 0.55, 1.04, and 0.52% in raw potato, respectively. Among them alkanes (2-lauroyloxy-1,3-bis-palmitoyloxy-propane and tritriacontan-17-ylcyclohexane) were the dominant flavor. The esters content in raw, MW, RF and IR heated samples were 0.52, 1.86, 2.70, and 0.92%, respectively, and the alkanes content were 1.42, 1.29, 2.23, and 1.04%, respectively. These quantitative and qualitative differences in flavor compounds created by the three drying procedures may be partially attributed to the variations in heat. Moisture content is a critical factor affecting the auto-oxidation, enzymic action and Maillard reaction. The RF drying had the highest flavor content (higher alkane and ester compounds) due to lower temperatures and drying period.