模型化合物十六烷在超临界水中的热解

Pyrolysis of Hexadecane as Model Compound in Supercritical Water

为了解重质油中饱和分在超临界水中的热解机理，将十六烷作为模型化合物，在间歇反应器内研究了它在超临界水中的热解反应，反应温度420-460℃，压力23-27MPa。在超临界水中，十六烷热解为较轻、较重的碳氢化合物和气体。与无超临界水、常压下十六烷的热解反应相比，超临界水中十六烷热解反应的活化能（300．0kJ／mol）低，因而反应速率快。通过对产物的分析，推断反应遵循自由基机理，反应过程包括自由基的产生、传递、分解和终结。在超临界水中，十六烷的热解反应存在超临界水的供氢机制，减压渣油在超临界水中的热解反应也存在这种供氢机制，而该机制有利于改善热解产物的质量。

Reaction mechanism of heavy oil pyrolysis in supercritical water（SCW） was studied at 420℃-460 and 23-27 MPa in batch reactor by using hexadecane as model compound. Hexadecane decomposed into light hydrocarbons, heavy hydrocarbons and gases under above mentioned conditions. Reaction rate and product composition of hexadecane pyrolysis in SCW were investigated. The overall apparent activation energy was about 300.0 kJ/mol,lower than that without SCW; therefore the reaction rate was faster. The analysis of product composition indicated that reaction followed free radical mechanism including initiation of free radical ,its transfer, decomposition and termination. Hydrogen donation mechanism of hexadecane pyrolysis in SCW was proposed and it was similar to mechanism of vacuum residue pyrolysis in SCW. This mechanism was favorable to upgrading quality of pyrolysis products.