Characterisation of Ion Exchange Resins for the Catalytic Conversion of Biorefinery Streams to Fuels

Abstract

This thesis describes the work performed to test and characterise various ion exchange resins
as heterogeneous catalysts for the transesterification reaction of tributyrin with methanol to
produce methyl butyrate as biodiesel. Depleting reserves of fossil fuel and environmental
restrictions on the emission of greenhouses gases have been drawing attention to find a
renewable resource such as biodiesel. Biodiesel can be produced via transesterification
reaction of oil using an acid or base as a homogenous catalyst. Due to the disposal problem
of these catalysts; a more sustainable alternative such as a heterogeneous catalyst is required.
Due to the lack of literature on the use of resins as a catalyst, in particular for anionic resins, a
preliminary study of the pre-treatment of ion exchange resins was initially carried out to build
the foundations for further experiments. Then, a screening test was performed to detect the
most promising catalyst. The strong anion exchange resins showed much higher catalytic
activity than the strong cation exchange resins. Among the anion exchange resins, Amberlyst
26OH with high density of functional groups and the ability to swell in the reaction mixture gave
rise to the conversion of approximately 88 %. The influence of the reaction parameters such
as temperature, molar ratio, catalyst loading and stirring rate was investigated by factorial
design.

The pore size and volume of resins can affect activity for triglyceride transesterification. A
proper study of the internal mass transfer on the resins was introduced here. Diffusion Ordered
Nuclear Magnetic Resonance Spectroscopy (DOSY NMR) has been utilized for the first time
to characterize the internal mass transfer using the motion of the reacting species, confined
within their pores. The measurements on the resins failed because of heterogeneity of the
samples and the presence of moisture. The results of these resins were compared with
mesoporous silica SBA-15, which allowed simple characterisation. Tributyrin and methyl
butyrate showed reduced diffusion coefficients within the confined pores. At the same time,
glycerol exhibited interesting behaviour; it showed enhancement of its diffusion coefficient due
to the ability of the silica support to disrupt the intermolecular H-bonding network of glycerol.
Ion exchange resins are high-performance catalysts and catalytically active even at very low
temperature. The work reported here enhance the use of ion exchange resins more used in
catalysis, and the

Date of Award	2021
Original language	English
Supervisor	Paul Topham (Supervisor) & Robert Evans (Supervisor)