2011 Annual Report
1a.Objectives (from AD-416)
Develop catalytic and non-catalytic technologies that enable commercially-viable processes for on-farm scale production of stable and transportable pyrolysis oils that meet boiler fuel or refinable crude oil specifications.
Sub-Objective 1: Quantify the effect of various agricultural feedstocks (varying in composition, maturation, post-harvest handling, and pre-treatment) on the pyrolysis process efficiency, kinetics, product yield (pyrolysis oil, syngas, and charcoal), and composition.
Sub-Objective 2: Develop commercially preferred catalytic and non-catalytic processes for on-farm scale production of stable and transportable pyrolysis oils that meet specifications as boiler fuel or refinable crude oils.
Sub-Objective 3: Develop technologies that enable commercially-viable fast pyrolysis and post-pyrolysis processes for biochar production from a variety of agricultural feedstocks.
1b.Approach (from AD-416)
A stepwise approach will be taken to address the objective by carrying out a series of experiments organized under the three sub-objectives. The first approach will involve screening of biofeedstocks using existing laboratory (desk-top) pyrolysis units to determine their potential use as second generation biomass feedstock. Under this same sub-objective, catalysts with the potential to stabilize pyrolysis liquid, when added to the biomass, will be screened. Under the second sub-objective large scale experiments will be carried out in the ARS fluidized-bed pyrolysis reactor with selected biomass and selected catalysts. Additional experiments will be designed under this sub-objective to explore non-catalytic pathways for producing stabilized pyrolysis oil. The next set of experiments, to be organized under sub-objective 3, will be designed to develop post-pyrolysis processes that will generate biochar with soil-amending, carbon sequestering properties. Modifications, incorporating changes that the experimental outcomes and analyses results will dictate, will be made to the pilot reactor system so as to make it compatible with the distributed scale systems envisioned for the on-farm approach.
Sub-Obj-1: (i) We continued analytical pyrolysis of several lignocellulosic biomass samples and fractional components of biomass using zeolite catalysts in a bench-scale analytical pyrolysis system coupled with gas chromatography and mass spectrometry (py-GC/MS). We successfully screened biomass/catalyst combinations to determine relevant trends in product yield and composition pathways towards fuel-like components. This helped design experiments for catalytic fast pyrolysis. (ii) We studied the effect of feedstock protein on the fast pyrolysis products. With this we compiled pyrolysis data on pyrolysis process yields, efficiencies and product quality for oil seed presscakes (mustard seed family), ethanol production residues (barley DDGS), legumes (alfalfa stems), low protein lignocellulosic materials (wood, crop residues) and aquatic species (eel grass). We learned that nitrogen from biomass with high protein content can drive out oxygen during the pyrolysis process to produce less acidic, higher energy and more stable oils.
This work relates to sub-objective 1: Quantify the effect of various agricultural feedstocks (varying in composition, maturation, post-harvest handling, and pre-treatment) on the pyrolysis process efficiency, kinetics, product yield (pyrolysis oil, syngas, and charcoal), and composition.
Sub-Obj-2: Non-catalytic Pyrolysis: We continued developing a method of pyrolysis vapor condensation with equipment that is practical at the farm scale (distributed processing) so that the cooled bio-oil can be stored for a few weeks before transportation to a bio-fuel refinery. Catalytic Pyrolysis: We investigated catalytic pyrolysis as a means to stabilize pyrolysis on pilot scale. This was in collaboration with CRADA partners who supplied appropriate catalysts. We embarked on three approaches (i) in situ catalysis with regeneration, (ii) cracking of pyrolysis vapors before they condensed, and (iii) condensed phase upgrading of produced pyrolysis oil via batch hydrotreating.
This work relates to sub-objective 2: Develop commercially preferred catalytic and non-catalytic processes for on-farm scale production of stable and transportable pyrolysis oils that meet specifications as boiler fuel or refinable crude oils.
Techno-economic Analysis: We have begun calculations of greenhouse gas consequences of biomass pyrolysis using LCA data assembled for several biomass types and locations and the ASPEN+ model created for a plant to pyrolyze 200 metric ton of biomass. We have also built a computational fluid dynamic (CFD) model to aid virtual design of fast pyrolysis reactors and their optimization to meet economic scales required for distributed or satellite units.
Better fast pyrolysis oils obtained from proteinaceous biomass. ARS researchers at Wyndmoor, PA, studied the fast pyrolysis of several feedstocks containing varying amounts of protein to determine its effect on the overall pyrolysis process and the composition and properties of the pyrolysis-oil. While the presence of the protein did not seem to significantly alter the overall pyrolysis oil yield, it was learned that nitrogen from biomass with high protein content can drive out oxygen during the pyrolysis process, resulting in a pyrolysis oil that is less acidic, contains more energy and in some cases even more stable than in cases where protein content is low. These findings suggest that production of biofuel intermediates from proteinaceous biomass via fast pyrolysis could have advantages over purely lignocellulosic biomass and were described in detail in a publication (Mullen and Boateng, Bioenergy Research; 2011 doi 10.1007/s12155-011-9130).
Boateng, A.A., Mullen, C.A., Goldberg, N.M. 2010. Producing stable pyrolysis liquids from the oil-seed presscakes of mustard family plants: pennycress (Thlaspi arvense L.) and camelina (Camelina sativa). Energy and Fuels. 24:6624-6632.
Mullen, C.A., Boateng, A.A. 2011. Characterization of water insoluble solids isolated from various biomass fast pyrolysis oils. Journal of Analytical & Applied Pyrolysis. 90:197-203.
Mihalcik, D.J., Mullen, C.A., Boateng, A.A. 2011. Screening acidic zeolites for catalytic fast pyrolysis of biomass and its components. Journal of Analytical & Applied Pyrolysis. 92:224-232.