A manifold destiny : advancing the frontiers of the ADOR process

Abstract

This thesis deals with the various attempts to expand the ADOR (Assembly, Disassembly, Organisation and Reassembly) process. This includes the use of the ADOR process to incorporate new elements into a zeolite framework, the expansion of the ADOR process to other germanosilicate frameworks, and the first ever synthesis of a new ADORable germanosilicate and its subsequent daughters. Chapter 4 deals with the expansion of the ADOR process to the already known ADORable zeolite UTL, using the organisation and reassembly steps to incorporate Al and P, resulting in the formation of a zeolite-AlPO hybrid with distinct silicate layers connected by AlPO based s4r linkages. The material was shown to contain Al and P species and was unstable to acidic medium, atypical of the wholly silica zeolite frameworks produced by the ADOR process. MAS NMR studies showed the presence of both tetrahedral P and Al species in the material and that the presence of Si-OH groups was limited. Indicating that the layers had been reconnected with Al and P now present, forming a zeolite-AlPO hybrid. 29 Si-enriched materials were synthesised to confirm the presence of P-O-Si bonds, through 2D MAS NMR correlation experiments; however, results were limited due to the lack of signal strength. Chapter 5 deals with attempts to expand the ADOR process by applying the ADOR process to other already known germanosilicates. It was found that the non-ideal ADORable candidates NUD-1 and ITQ-33 were unable to undergo a controlled disassembly process, primarily due to their high Ge content and distribution of d4r/d3r. The zeolites ITQ-38 and IM-20 showed more promise. Both could undergo disassembly to form a layered material, which could then be organised and reassembled to form new materials. However, these materials were shown to not form perfect daughter zeolites and had a high degree of disorder. This was associated with the complexity of the ADOR process and the many factors that play a role in each step. Chapter 6 deals with the use of a family of SDAs (with the same biphenyl backbone) to synthesise new ADORable zeolites. The synthesis of the SDAs and their use in various zeolite syntheses was discussed. The potential of these SDAs for the synthesis of new zeolites was then evaluated. The investigations were relatively successful with the successful formation of an ADORable zeolite, which was already known, UTL. However, the suitability of such SDAs also put into question, due to their instability under hydrothermal conditions. Chapter 7 discussed the first successful a priori synthesis of a parent germanosilicate and its daughter zeolites by the ADOR process. The successful synthesis of an ADORable zeolite (SAZ-1) was conducted with the use of an imidazolium-naphthalene based SDA. Investigations were first conducted into changing the synthesis condition, exploring the impact of these changes on the resulting products, and optimising the synthesis conditions to favour the formation of the new zeolite SAZ-1. These investigations led to the new zeolite framework SAZ-1, which showed similarities to the zeolites NUD-2 and CIT-13, which were developed simultaneously by other institutions. The properties of the SAZ-1 framework were discussed and were found to be highly suitable for the ADOR process. SAZ-1 was then successfully disassembled, organised, and reassembled to form two new daughter zeolites SAZ-2 and SAZ-3. The alumination of SAZ-1P to form aluminated SAZ-2 and SAZ-3 was also attempted. Both zeolites showed an increase in catalytic activity, compared to the typical pure-silica daughter zeolites. The layers of SAZ- 1P were also able to undergo the same shifting process as seen for the ‘unfeasible’ zeolites IPC-9 and IPC-10, but the resultant products were not as ordered as these previous examples. This in addition to the previous work highlighted some of the non-ideal properties of SAZ-1 compared to other ADORable zeolites, like UTL.