Designing palladium functionalised hierarchical zeolites for catalytic biorefinery reactions

Abstract

Catalytic cascades for chemical production represent attractive approaches to escalate the efficiency of multistep chemical synthesis. However, cascade processes typically encompass different classes of chemical transformations, often requiring different types of active catalytic sites, which may require separation from each other. The coupling of two or more unique sites, within a single solid catalyst, requires sophisticated synthesis strategies to fashion catalysts designed to dictate the order in which each site is encountered during cascade reactions. Mesoporous-microporous hierarchical zeolites, which are prepared by facile post-treatments of commercial zeolite, can be an ideal catalyst support architecture to provide two specific regions (i.e. mesopore and micropore) that can satisfy the requirements of the catalysts for cascade reactions. In these so-called spatially segregated catalysts, compartmentalising different active species in different regions can dictate reaction sequence order and prohibit interaction between the different catalytic species. This PhD aimed to develop an innovative strategy to prepare spatially segregated catalysts comprising Pd in mesopores and acidity within micropores of hierarchical zeolite crystals and demonstrate their application for the catalytic cascade of biomass-derived lauric acid HDO to alkanes. Specifically, the project conducted (i) the systemiatic investigation of the conventional wet impregnation method to load Pd over hierarchical ZSM-5 with differing acidic properties (i.e., H-form and Na-form) and compared with two microporous ZSM-5 counterparts; (ii) the development of spatially segregated catalysts by retaining inherent acidity solely within micropores of hierarchical mesoporous-microporous ZSM-5 via selective extraction, and depositing preformed Pd nanoparticles over mesopores; (iii) the investigation of the spatially segregated catalysts for one-pot cascade hydrodeoxygenation of biomass-derived lauric acid to alkanes and comparing the performance with conventional impregnated catalysts; (iv) the evaluation of zeolite intrinsic silicon and aluminium ratio and micropore size on spatially segregated catalysts for HDO of lauric acid.

Date of Award	31 Dec 2023
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Christopher Parlett (Supervisor) & Xiaolei Fan (Supervisor)