(46f) Comparison between Catalytic Fast Pyrolysis and Catalytic Fast Hydropyrolysis of Arundo Donax in a Fluidized Bed Reactor

Comparison Between Catalytic Fast Pyrolysis and Catalytic Fast Hydropyrolysis of Arundo Donax in a Fluidized Bed Reactor

D.S. Chandler, F.L.P. Resende

Alternative fuels for transportation need to be compatible with our current liquid-fuel infrastructure, cheap, and readily available. Catalytic fast pyrolysis (CFP) and catalytic fast hydropyrolysis (CHP) of biomass can make such a fuel. CFP breaks down lignocellulosic polymers into volatile organic liquids and catalytically transforms them into compatible hydrocarbon fuels by deoxygenation with a solid catalyst. CHP uses of pressurized hydrogen gas to aid this process. Both can be performed either in a single unit (in-situ) or in a sequence of two units (ex-situ). With a sufficiently fast-growing, cheap feedstock, CHP could meet much of the transportation needs of our society.

Arundo Donax is a fast-growing herbaceous weed. It requires little input, and grows faster than any other lignocellulosic feedstock [1]. Furthermore, there is a need to eliminate it from the habitats it is invading [2]. A profitable means of getting this invasive weed out of the ecosystems is desired. The fast growing rate of the feedstock could be what is necessary to economically supply alternative fuels for our transportation sector in the near future.

In this work, we investigated the use of HZSM-5 to convert Arundo Donax into liquid hydrocarbons via CFP, varying the temperature from 400 to 625 °C, the weight hourly space velocity (WHSV, the feed rate of biomass divided by the weight of catalyst) from 0.5 to 3.3 hr^-1, and the pressure from 1 to 35 bar. Then, we introduced hydrogen gas (CHP) as a reactant and investigated its effects at 35 bar and 400°C. Finally, we added nickel to the HZSM-5 catalyst at loadings from 0.55 to 1.51 wt% and investigate its effects on both CFP and CHP.

Our findings showed that liquid hydrocarbons can be produced with HZSM-5 catalyst, but that coking reduces the longevity of the catalyst. Adding hydrogen as a reactant to perform hydropyrolysis mildly reduces coking and increases hydrocarbon yields. Doping the catalyst with nickel and performing hydropyrolysis also reduces the coke yield but does not always increase the yield of hydrocarbons, often cracking liquid products to methane instead.

[1] C. Williams, T. Biswas, A. Downie, Yield , salt tolerance and energy from Arundo donax : a potential biochar and biofuel crop, in: 1st Asia Pacific Biochar Conf., Queensland, AU, 2009.

[2] J. Giessow, Jason; Casanova, Jason; Leclerc, Rene; MacArthur, Robert;Fleming, Genie;Giessow, Arundo Distribution and Impact Report, (2011).