(206g) Selective Hydrogenation of 5-Hydroxymethylfurfural to 2,5-Dihydroxymethylfuran Using Octahedral Molecular Sieve Support As Catalyst

Selective
Hydrogenation of 5-Hydroxymethylfurfural to 2,5-dihydroxymethylfuran using
Octahedral Molecular Sieve support as Catalyst

Jennifer Sarah Dicks, Kathryn
Ralphs, Manish Tiwari, Laura Marti, Vivek. V. Ranade
and

Haresh G. Manyar*

School of Chemistry and
Chemical Engineering

QueenÕs University
Belfast

Belfast BT9 5AG

Email: h.manyar@qub.ac.uk

Introduction:

With an increasing
energy demand, growing population and depleting crude oil resources, there is
an impending need for development of alternative renewable energy and chemical
processes. In this context, functionalised furans are an attractive biomass
derived feedstock, they can be sustainably produced at large scale from
abundant waste biomass. 5-Hydroxymethyl furan (HMF) is a key platform chemical,
which can be converted into several value-added products including;
hydrogenation to 2,5-dimethylfuran (DMF), 2,5-Bis(hydroxymethyl)furan (BHMF),
subsequent rearrangement to para-xylene and 2,5-dihydroxymethyl-tetrahydrofuran
as well as oxidation to 2,5-Furandicarboxylic Acid and Diformylfuran for
applications in biofuels, fuel-additives, platform chemicals, polymers,
bio-degradable plastics, antifungal agents and ligands.^[1-2] In this
study, we have developed a catalytic process for selective hydrogenation of HMF
to BHMF, under mild reaction conditions, low hydrogen pressures and water as
reaction medium. Although there are reports in literature, for selective
hydrogenation of HMF, the reported processes are mainly performed using dilute
feedstocks in organic solvents, expensive designer catalysts, stringent reaction
conditions, which limit the scope for scale up and potential commercialization.
In this study, we have developed a facile and scalable hydrogenation process
for selective hydrogenation of HMF under mild reaction conditions, using water
as reaction medium, using manganese oxide octahedral
molecular sieves (OMS-2) and Pt/OMS-2 catalysts, which
makes our process industrially attractive and economically viable for scale up
studies. We have previously shown octahedral manganese
oxide with 2x2 tunnel structure (OMS-2), octahedral layered (OL) and metal
doped OMS-2 and OL to be robust, versatile and efficient catalysts for selective
hydrogenation of a,b-unsaturated aldehydes, ketones, nitroarenes and phenylacetylene. In
continuation of our interest in liquid phase hydrogenations using octahedral
manganese oxides,^[3-4] herein, we have reported the first complete study
of selective hydrogenation of HMF to BHMF using manganese oxide materials
including kinetic analysis and insights on the role of lattice oxygen vacancies
and alkali metal ions on the plausible reaction mechanism.

Materials and
methods:

OMS-2 and Pt/OMS-2 catalysts were synthesized at QUB
and thoroughly characterized using XRD, XPS, BET, TPR, Raman, SEM and HRTEM
analyses. Hydrogenations were
carried out in a 100 cm³ Autoclave Engineers autoclave. In a typical
experiment, the reactor was charged with HMF (0.004 mol) and catalyst (0.15 g)
suspended in water (30 cm³). The reactor was purged three times then
pressurized to 20 bar H₂ and heated to 110 ¡C and the reaction
mixture was agitated at 1500 rpm. The reaction was monitored by sampling at
regular time intervals, with analysis by GC.

Results and
Discussion:

In the
hydrogenation of HMF to BHMF using 4%Pt/OMS-2 catalyst, at 110 ^oC,
and hydrogen pressure of 20 bar, the reaction was completed in less than 1
hour, with 92% selectivity to BHMF. A typical HRTEM image of the 4%Pt/OMS-2 catalyst is shown in
Figure 1a and the reaction composition-time profile is
shown in Figure 1b. The activity of different metals such as Pt and Pd
supported on TiO2 and OMS-2 were compared and 4%Pt/OMS-2 showed the highest
selectivity to BHMF (Figure 1c). To further optimize the hydrogenation process,
reactions were carried out between
5 to 20 bar H₂, 60 to 110 ¡C temperature and 0.05 to 0.3 mol dm^-3
HMF feed concentration, 0.5 to 4% Pt loading and 0.001 to 0.005 gm/cm³
catalyst loading.

Figure 1 (a) HR-TEM image of 4 wt% Pt/OMS-2, (b)
Reaction composition-time profile for hydrogenation of HMF using 4%Pt/OMS-2,
and (c) Efficacy of various catalysts.

In this study, we have developed a selective hydrogenation process for
conversion of HMF to BHMF under mild reaction conditions using water as the
reaction medium. The dissociation of hydrogen on the catalyst surface is water
assisted and selectivity to BHMF is controlled by the adsorption geometry of
HMF on OMS-2 and Pt nanoparticles. The catalyst is stable, active, and
selective and shows good reusability over many operational cycles. Effects of
different process parameters were studied and reaction mechanism and kinetic
model developed. The process is green and novel for synthesis of BHMF from HMF.
 

References

[1] Chen J.,  Ge Y., Guo Y., Chen J.,
J. of Ene. Chem., 2018, 27, 1, 283.

[2] Bing
L., Zehui Z., Kangle L., Kejian D., Hongmin D., App. Catal. A: Gen., 2014, 472,
64.

[3] Manyar H. G., Yang B., Daly H., Moor H., McMonagle S., Tao Y.,
Yadav G. D., Goguet A., Hu P., Hardacre C., ChemCatChem, 2013, 5, 2,
506.

[4] Manyar H. G., Morgan R., Morgan K., Yang B., Hu P., Szlachetko
J., Sa J., Hardacre C., Cat. Sci. &  Tech., 2013, 3, 1497.