An Experimental Investigation of the Reactivation of Coked Catalysts under Supercritical Fluid Conditions

本项目的目标是用超临界流体(SCF)溶剂对结焦催化剂的再活化进行实验研究。具体地说，讨论了以下几点：(A)超临界流体溶剂从多孔催化剂中提取焦炭形成化合物的效果如何？(B)是否有可能通过用超临界流体溶剂定期提取结焦化合物来保持催化剂的就地活性，从而防止在催化剂中积聚焦炭？这些问题是通过对铂/γ-氧化铝催化的1-己烯异构化的系统实验研究来解决的--1-己烯是一个同时经历结焦失活的反应体系。该反应在高压反应釜中进行，而催化剂的再活化则在高压平衡槽中进行。所使用的超临界流体溶剂为超临界二氧化碳。除了可以在现场进行催化剂再活化外，与传统工艺相比，拟议的再活化方案还可以在相对温和的温度下进行操作。因此，催化剂和载体的任何热失活都是最小的。该项目的成功完成将带来设计新的、节能的催化剂再活化方案的潜力。此外，本研究提供的信息也可用于理解超临界流体从固体煤或任何多孔基质中提取低分子组分的过程。

The objective of this project is to experimentally investigate the reactivation of coked catalysts using supercritical fluid (SCF) solvents. Specifically, the following points are addressed: (a) How effective is an SCF solvent in the extraction of coke forming compounds from a porous catalyst? (b) Is it possible to maintain catalyst activity in situ by periodically extracting the coke-forming compounds with an SCF solvent, thus preventing any accumulation of coke in the catalyst? These questions are addressed through systematic experimental investigations of the platinum/gamma-alumina-catalyzed isomerization of 1-hexene -- a reaction system that undergoes simultaneous deactivation by coking. The reaction is carried out in an autoclave reactor, while catalyst reactivation is performed in a high-pressure equilibrium cell. The SCF solvent employed is supercritical carbon dioxide. Besides the possibility of performing catalyst reactivation in situ, the proposed reactivation scheme also operates at relatively mild temperatures as compared to conventional processing. Hence any thermal deactivation of the catalyst and support is minimized. Successful completion of this project should bring out the potential for devising novel, energy- efficient catalyst reactivation schemes. Besides, information from this research also has application in the understanding of SCF extraction of lower molecular-weight constituents from solid coal or any porous matrix in general.