Reaction probability temperature jump

Conversion of polymers and biomass to chemical intermediates and monomers by using subcritical and supercritical water as the reaction solvent is probable. Reactions of cellulose in supercritical water are rapid (< 50 ms) and proceed to 100% conversion with no char formation. This shows a remarkable increase in hydrolysis products and lower pyrolysis products when compared with reactions in subcritical water. There is a jump in the reaction rate of cellulose at the critical temperature of water. If the methods used for cellulose are applied to synthetic polymers, such as PET, nylon or others, high liquid yields can be achieved although the reactions require about 10 min for complete conversion. The reason is the heterogeneous nature of the reaction system (Arai, 1998). 

A collision between two adatoms is said to occur when an adatom, in the course of hopping, finds itself at a potential energy maximum, S, adjacent to a potential well occupied by another adatom. Collisions cannot occur between two adatoms in transit this is because, at the temperatures used for these reactions, the great majority of the adatoms follow the profile of the potential energy cmwe of the surface and jump only to neighboring sites. The chance that, on its first jump, an adatom will find the adjacent site vacant is 1 — The chance that the adjacent site is occupied and, therefore, that a collision can be said to have occurred, is 0. If y is the probability that a collision between two adatoms results in the formation of a molecule, either in a physically adsorbed state or in the gas phase, then yO is the chance that a molecule will be formed as the result of the adatom s attempting to move into an adjacent site which is already occupied. The chance that reaction does not occur as the immediate consequence of the collision is 0 l—y). The chance that the adatom will come to rest in a vacant site subsequent to this unsuccessful encounter is 1 — and the overall probability for the sequence is 0 l—y) l — 0). The probability that, immediately... 

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