Due to the increasing pollution of the environment through emissions and
invasion on nature, any alternative option for the production of chemicals is welcome.
One way we can reduce our dependence on fossil fuels and alleviate greenhouse gas
emissions is to use renewable resources. Nowadays carbohydrates and especially glucose,
is the one that attracts a lot of interest as a renewable raw material This is due to the fact,
that it can be converted into sugar acids, which are the starting point in the production of
chemicals.
One of the most important sugar acids is glucaric acid, as it provides a renewable
alternative in the synthesis of adipic acid, which is needed as a raw material in the plastics
and textiles industry, among others.
Currently, glucaric acid is obtained by electrochemical or stoichiometric oxidation using
undesirable reagents such as NaBr, NaOCl, and various bleaches. The most common,
however, is a process that involves the oxidation of glucose with concentrated nitric acid,
as this is the most economical process, but it is very harmful to the environment.
Recently, however, a promising, more environmentally friendly glucose oxidation
process has been developed. The reaction is carried out in the presence of metal catalysts,
at an elevated temperature of about 100 °C and a pressure of 40 bar, using molecular
oxygen is used as the oxidant.
For my study I synthesized a 10 % Ag/ZrO2 catalyst, which I then used in glucose
oxidation. I compared its efficiency and selectivity with a commercially available 10 %
Au/TiO2 catalyst (anatase + rutile). The goal was to obtain glucaric acid, but I failed to
do so with the aforementioned catalysts. As a product, gluconic acid was formed, which
is a precursor of glucaric acid. I believe that the conversion to glucaric acid failed due to
the low oxidation capacity of the catalysts.
|
