<p>Producing bio-based
commodity chemicals, such as polymers and fuels, is of significant interest as
petroleum reserves continue to decline. A major roadblock to bio-based
production is high processing costs. These costs are associated with the need
for highly-specialized catalysts to produce bio-based commodity chemicals from
agricultural products and wastes. This prevents bioprocessing facilities from
fully taking advantage of commodities of scale, where purchasing materials in
greater quantities reduces the material cost. Discovering catalysts capable of
being used in multiple production pathways could reduce the per unit processing
of a biorefinery. <br>
Recent works have shown that maleic acid can be used for multiple conversion
reactions of plant material to valuable products: xylose to furfural, glucose
to hydroxymethylfurfural (HMF), and the pretreatment of lignocellulosic material
for second generation biofuel production. This work evaluates the use of maleic
acid as a catalyst for producing HMF from corn starch, with a specific focus on
reducing operating costs. Additionally, the use of maleic acid as a
liquefaction catalyst for producing corn stover slurries is tested. </p>
<p>To evaluate HMF
production from starch, a combined computational and experimental approach is
used. Through modelling and experimental validation, molar HMF yields of ~30%
are reached by incorporating dilute dimethylsulfoxide and acetonitrile into the
reaction mixture. However, HMF yield was limited by low stability in the
reaction media. The addition of activated carbon to the reactor overcomes
challenges with second order side reactions, resulting in HMF selling prices
that are competitive with similar petroleum-derived chemicals. The key
technical roadblocks to commercialization of HMF production are identified as
solvent recycling and HMF separation efficiency in a sensitivity analysis.
During liquefaction of corn stover, maleic acid was found to reduce the yield
stress required to begin slurry flow through a pipe. However, a reduction in
the free water content of the reactor through binding of water in the matrix of
biomass limited liquefaction, resulting in solids concentrations not
financially feasible at scale. To overcome this, maleic acid treatment was
performed at solids contents of 25%, followed by a water removal step and
enzymatic liquefaction at 30% solids. Yield stress was reduced from >6000 Pa
for untreated samples to ~50 Pa for samples treated with maleic acid and
enzymes sequentially. Such treatment reduces the challenges associated with
feeding solid biomass into a pretreatment reactor. Additionally, reduced slurry
yield stress results in lower capital costs, since smaller pumps can be used in
the production facility. </p>
This work provides a step forward in
transitioning away from a petroleum-based economy to a bio-based economy
without significant disruptions in product pricing and availability.
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/11918208 |
| Date | 12 October 2021 |
| Creators | Jonathan Christopher Overton (8481489) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/Maleic_acid_as_a_versatile_catalyst_for_biorefining/11918208 |
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