Effect of temperature in the radiolysis of paraffins

Abstract

Publication costs assisted by the Federal School of Technology The radiolysis of n-paraffins with 5 to 16 carbon atoms is reviewed. The G values of the products, excepting dimers, are approximately the same for all the above paraffins. The temperature dependence is expressed as an apparent activation energy. The material balance shows that the product analysis is not complete and that the missing substances have a molecular weight higher than that of the dimers. The hydrogen production is divided into three processes: unimolecular hydrogen production, abstraction by thermal atoms, and abstraction by "hot" hydrogen atoms.The radiolysis of liquid n-paraffins has been described in a large number of publications (see, e.g., ref 1-3). In most cases the aim of the work was to study the product distribution or influence of additives in the radiolysis of one particular paraffin. If the number of significant products from re-hexane is say 40, then it is likely to increase well over 100 for re-decane. Since the product formation depends also upon temperature, it is somewhat difficult to draw conclusions concerning the general behavior of reparaffins. In this work we have attempted to describe a general mechanism which shows the yield of products together with their temperature dependence in the radiolysis of re-paraffins in order to survey the field. Our approach is broad and pragmatic: we will classify the products and try to find average G values for all re-paraffins.The temperature dependence of these values is expressed as apparent activation energies obtained by plotting In G vs. 1/T. We are well aware of the fact that these energies may have no theoretical significance. Our aim is to try to

Simultaneous Application of Heat and Electron Particles to Effectively Reduce the Viscosity of Heavy Deasphalted Petroleum Fluids

“…Radiation-induced excited molecules can be the potential source of H 2 generation. The evolved hydrogen has two origins: it may be formed through a molecular elimination or a hydrogen atom mechanism. − For the case of molecular elimination, the excited hydrocarbon (A*) loses a hydrogen molecule, resulting in an unsaturated molecule (A unsaturated ). This process is also called unimolecular hydrogen formation. A * → A uns a turated + H 2 …”

Radiolyse des hydrocarbures. 21e communication. Mécanismes radicalaires et non‐radicalaires dans les n‐alcanes en phase liquide

“…On obtient des rendements non radicalaires diff6rents pour les alcanes (Gnr = 0,9) et pour les alcknes (Gnr = 0,Z) et on ne peut les expliquer entihrement par les reactions souvent proposkes du type Les calculs de rendement ont 6tC faits avec les hypothkses suivantes: second: kd(IIb,) = 3kd(IIb*) = 3/4kd(11) [17]. Tableau (VIII) dont nous n'avons pas tenu compte dans les calculs de rendements radicalaires.…”

“…La radiolyse de l'hexane A -78" en prCsence d'iode [5] montre pourtant que les hexbnes diminuent de 37%, indiquant une formation partielle importante d'hexhes par rdaction radicalaire. rkcentes publications [7-151 permettent de se faire une idCe de l'importance du rapport kd/k, et de sa variation avec la tempCrature et avec le changement de phase (voir tableau V dans[17]). La plupart des determinations ont 6tC faites en phase gazeuse et avec les diffbentes valeurs kd/k, obtenues pour les radicaux en phase liquide on peut tirer, pour le rapport kd/k, en phase liquide, les conclusions…”

Radiolyse des hydrocarbures. 20e communication. n‐Alcanes en phase liquide de l'heptane au dodécane

“…-Les n-alcanes pr6sentent approximativement les d m e s types de liaison C-C et C-H. On peut donc s'attendre pour tous les alcanes irradids a une grande similitude dans les valeurs Go obtenues ainsi que dans la variation de ces valeurs avec la tempkraturc. C'est ce que montre le tableau 8 dont les chiffres bads essentiellement sur les rCsultats de ce prCsent travail, ont 6tC calcul6s ailleurs[13]. Le rendement radiolytique de l'hydrogkne, des produits de bas poids mol6culaire (PBPM), des alc5ncs CnHZn correspondant A l'alcane irradik ct des produits intermddiaires cst indkpendant du nombre de carbones de l'alcane irradi6.St:uls les alckncs C,HZ, ont un Go ne dependant pas de la temp6rature.…”