(271h) Residual Biomass As Feedstock for Production of Fuel or Value Added Products Via Pyrolysis

Due to the natural resistance of plant cell walls to microbial and enzymatic rupture, biochemical transformations of lignocellulosic materials are particularly difficult to carry out (Himmel et al., 2007). Pyrolysis arose as a process of choice for these kind of materials because it can transform biomass producing liquid, gas and solid products (Lim et al., 2016).The liquid, known as bio-oil, is universally regarded as a source for fuels and chemicals (Bridgewater, 2012).

As a source of lignocellulosic material, sunflower seed hulls are abundant residues of the edible oil industry, especially in the south region of Buenos Aires, Argentina, where approximately 22 thousand tons are accumulated per year. This material could be considered a very promising source of biomass for carrying out pyrolysis processes for either fuel or value added products (VAP) production, due to the amount produced each year and the fact that the raw cost material is null, because it is otherwise a waste mainly used for energy production by burning. The environmental issues derived from the hulls burning include fumes and unpleasant odors, and it looks more sensible to find a profitable use.

There are several possible products to be obtained after the hulls are pyrolyzed, depending on the conditions of the pretreatment and the process itself. In particular, after the fast pyrolysis is performed, a mixture containing a bio char and a bio liquid is obtained. The bio char can be used for example as a replacement for coal, while the bio liquid must undertake several purification steps in order to obtain the desired products.

Continuing our interest in adding value to sunflower seed hulls, we analize the production of furfuryl alcohol after the pyrolysis and bioliquid separation is performed. As it was already mentioned, after the pyrolysis, in a first step a bio-oil rich in furfural is obtained from the pyrolysis of the hulls. Second, this bio-oil is sent to a catalytic treatment for converting furfural into furfuryl alcohol, using Pd based catalysts in a Batch reactor under mild conditions (at 110°C and 0.4 MPa of H₂). The Pd based catalysts, Pd/BCs, used for the laboratory scale process, are prepared by supporting palladium on bio-chars which are also a co-product of pyrolysis of the hulls. The conversion of furfural and the selectivity to furfuryl alcohol are analyzed for the different catalysts, in the context of the evaluation of the possibility of producing VAP from the hulls (Casoni et al, 2018)

In this work, besides the experimental work done in order to find the best laboratory conditions for the production of value added products derived from the pyrolysis of sunflower seed hulls, a mathematical model of a large scale process is proposed and embedded into a superstructure considering different alternatives for pretreatment, pyrolysis conditions, post-pyrolysis separation of the bioliquid, catalyst selection including but not limited to preparation on bio chars, and post catalytic hydrogenation step separation of products is set up, with models based on first principles at a conceptual level, including mass and energy balances. A Generalized Disjunctive programming problem is now posed in order to find a setup using as objective function the Net Present Value. This constitutes a deeper study of the process presented in Casoni et al (2018), where an initial proposal was presented for an industrial scale facility.

Besides the furfuryl alcohol, several value added products can be obtained from agro-industrial residues by applying the methodology introduced in this study, thus new green processes for replacing the traditional ones can be developed.

References

Bridgewater A.V., 2012. Review of fast pyrolysis of biomass and product upgrading. Biomass Biosenergy. 38, 68-94.

Casoni, A.I., Volpe M.A., Hoch P.M. Gutierrez V.S., 2018. Catalytic conversion of furfural from pyrolysis of sunflower seed hulls for producing bio-based furfuryl alcohol, Journal of Cleaner Production 178, 237-246

Himmel M.E., Ding S.Y., Johnson D.K., Adney W.S., Nimlos M.R., Brady J.W., Foust T.D., 2007. Biomass recalcitrance: engineering plants and enzymes for biofuels production, Science 315, 804-807.

Lim, C.H., Mohammed, I.Y., Abakr, Y. A., Kazi, F.K., Yusup, S., Lam, H. L., 2016. Novel input-output prediction approach for biomass pyrolysis. J. Clean.Prod. 136, 51-61