Zeolite catalysts for nitric oxide production

Abstract

This thesis considers the nitric oxide production from a range of zeolite catalysts with either acid or copper active sites. The aim of the research was to find potential candidates for stent coatings that could help to prevent stent thrombosis.

Acid site mordenite, ferrierite, SSZ-13 and ZSM-5 are studied in chapter 4 for the catalytic conversion of sodium nitrite to nitric oxide. All zeolites successfully produced nitric oxide, with ranging levels of conversion from 14 – 24 %. Recycled samples revealed the consumption of the acid site, rendering the acid site zeolites non-catalytic.

Copper site zeolites were considered in chapters 5 and 6, with copper mordenite, ferrierite, SSZ-13, ZSM-5 and UZM-4 being studied. All zeolites successfully converted sodium nitrite to nitric oxide, with SSZ-13, ZSM-5 and UZM-4 producing around 100 % conversion. The use of cysteine as a sacrificial reductant to activate the copper sites allowed catalytic nitric oxide production. The promising catalytic tests led to further studies of the materials, including copper leaching and toxicology.

Chapter 6 looked further into the catalytic copper zeolites with nitric oxide flow studies and polymer incorporation. Flow studies showed sustained levels of nitric oxide production. Incorporation of the zeolite powders into the polymer of intrinsic microporosity, EATB(Me), showed good nitric oxide production from the initial studies. Recycled samples, however, showed a drop in production.

Lastly, chapter 7 explored the use of the ADOR (Assembly-Disassembly-Organisation- Reassembly) process to generate a series of zeolites for catalysis. Aluminium was incorporated into zeolites IPC-2, 4 and 6 through the organisation step to create aluminated zeolites. The aforementioned zeolites, as well as Al-UTL, were assessed for nitric oxide production with acid active sites. The results showed an interesting relation between ring size and nitric oxide production, with the largest rings of Al-UTL having the highest production and the smallest rings of Al-IPC-4 having the lowest.