碳氢燃料在分子筛催化剂上超临界催化裂解反应中的积炭沉积和失活模型研究

The supercritical catalytic cracking of hydrocarbon fuels over zeolite catalyst which has the advantages of high conversion and the adjustable products distribution, becomes the research focus of endothermic fuels for the active cooling system of hypersonic flight vehicles (HFV), However, the coke deposits and deactivation of the catalyst following with the catalytic cracking reactions has limited its application as endothermic process. Therefor, in this proposal, the model for coke deposit is built according to a simple physical moedel called "tangential micro-tanks in series", which is employed to describe the behavior of touring of reactant molecules from the inlet to the outlet of the catalyst bed. According to the balance of coke formation and in situ supercritical extraction of coke and/or coke precursor, coke deposit model including two items representing for both intrinsic coke formation and supercritical extraction is proposed. The model parameters were estimated by fitting the experimental data obtained from experiment carrying out on fixed bed reactor, and the statistical significancen test and verification experiments are conducted as following. Further, the coke deposit model is applied on the supercritical catalytic cracking of hydrocarbon over microchannel reactor coated with HZSM-5 zeolite, and further modified by the experimental data obtained. The build of the coke deposit model on the endtothermic process of the supercritical catalytic crackig of hydrocarbon fuels will provide theoretical basis for the research of HFV.

碳氢燃料的超临界催化裂解反应具有反应转化率高、产物选择性易调控等优点，成为高超音速飞行器（HFV）主动冷却燃料领域的研究热点。然而，在反应过程中催化剂中的积炭与失活是其应用的最大障碍之一。因此，本项目针对分子筛催化剂在碳氢燃料超临界催化裂解反应中的积炭沉积问题，提出了反应物分子在催化剂床层中运动与反应的简化物理模型"切向微釜串联"模型。再结合反应过程中积炭沉积规律，积炭前驱体的超临界萃取规律，建立包含积炭本征生长项和超临界萃取项的积炭沉积模型，其模型参数是通过在固定床反应器中进行实验得到的数据拟合，并给出统计检验和试验检验。然后，将上述积碳沉积模型应用于催化剂涂层管式反应器中的超临界催化裂解反应，并对模型进行修正，得到适用于该反应器的积炭沉积模型，为催化裂解吸热反应在HFV上的应用研究提供理论基础。

酸性分子筛催化剂在烃类催化转化过程中的积炭沉积是导致其失活的主要原因之一，积炭的化学结构、沉积位置和数量分布等特征共同决定了催化剂的失活规律。本项目以自主搭建的程序升温氧化（TPO）装置为主要仪器，通过对积炭氧化过程中的CO2、CO和H2O信号的在线监测得到完备的TPO图谱，通过对TPO图谱的解析，可得到积炭的上述三种分布的具体数据。然后，通过改变正十二烷在HZSM-5分子筛上超临界催化裂解的反应条件，得到反应积炭在反应过程中的生长历程，以及空速、反应压力等条件对积炭沉积的影响规律。本项目的初始立足点是建立积炭分布定量特征与催化活性之间的定量模型，在实际执行过程中由于超临界条件的可控性较差，数据的重复性难以很好地进行控制，因此暂未实现建立数学模型的目标，在项目结题后，我们将继续努力，将积炭规律的研究从定性层面逐渐推进到定量的层次，最终实现数学建模的目标，为催化剂积炭与失活这一普遍而重要的课题研究提供有益的借鉴。