Renewable Routes to Porous Aluminosilicate Materials

The objectives of this project were to synthesise zeolites and aluminosilicate materials
from silicon sources derived from biomass ashes. These materials will have great
potential as catalysts and adsorbents.
In order to begin this study it was necessary to find and optimise a technique for
extraction of silicon to an alkali silicate solution from biomass ashes. It was then
necessary to develop a technique for analysis of the alkali silicate solutions. This was done
using calibration of integrals from infrared spectra.
An optimisation of the synthesis of Zeolite X from a rice hull ash derived alkali silicate was
developed and these materials were analysed and characterised using XRD, N2 Adsorption
porosimetry, X‐Ray Fluorescence Spectroscopy, and X‐Ray Photoelectron Spectroscopy.
An in‐depth study of the surface of the ash derived and reference Zeolite X was
undertaken using in situ small molecule probing FT‐IR. It was found that although the
materials were similar there was a significant difference due to the presence of a strongly
bonded carbonate species in the pores of the bio‐derived zeolite.
Synthesis of a Miscanthus ash derived mesoporous silica, MCM‐41, was successfully
achieved which was comparable to its conventionally synthesised equivalent. Both
displayed ordered hexagonal pores and high surface areas. A study on addition of
different sources of aluminium found that it was possible to introduce aluminium into the
structure successfully. Included in this study was the addition of the waste product ‘red
clay’ as an aluminium source.
Another mesoporous silica, SBA‐15 was synthesised from a Miscanthus ash derived alkali
silicate. It was necessary to optimise the synthesis to adapt to the different pH systems of
the conventional method and bio‐derived alkali silicate solutions. This was achieved and a
bio‐derived SBA‐15 material with ordered hexagonal pores was produced.