Advanced Research in the development of green and sustainable processes for high-value chemical production from biomass.

Abstract

This thesis presents the studies of controlling surface acidity of alumina-based catalysts for biomass conversion. Via the application of different synthesis approach, this thesis developed wet-chemistry method to establishes penta-coordinated aluminium specie based Brønsted acid site on varied mixed oxide and to precisely adjusts the spatial location of Brønsted acid site and Lewis acid site. In Chapter 3, for the first time, the development of AlV-BAS has been achieved on non-silica alumina material, and the principle of the research outcome can be applied to the AlV-BAS formation within many other mixed oxide systems. Because that the current development of AlV-BAS requires complex and expensive preparation method, which render the AlV-BAS based acidic catalyst less optimal to its counterparts, in this scenario, in Chapter 4, for the very first time, a simple and cheap wet-chemistry synthesis route has been reported in order to prepare silanol linked AlV-BAS for acidic catalysis. This achievement presents promising opportunities for the large-scale industrial implementation of mesoporous silica-alumina with AlV-BAS. Moreover, there are many acidic reactions requires both Brønsted acidity and Lewis acidity. Nevertheless, the currently applied bi-acidic catalysts has limitations, such as uncontrolled diffusion on acid sites and uncontrolled Brønsted-Lewis acid site synergy. With this in mind, we put efforts on preparing catalyst with cascade structure for active site separation. In Chapter 5, a bi-acidic solid acid catalyst with cascade architectural structured BAS and LAS has been reported. Due to the spatial separation, the synergy between BAS-LAS pair was limited, and which also showed the ability to direct the diffusion flow from BAS to LAS and contributed to enhanced cascade acid reaction performance. We reckon this work paves the way for designing bi-acidic catalyst with unique cascade architectural structure for efficient cascade reactions.