1: Develop pyrolysis processes that enable the commercial production of marketable, partially-deoxygenated pyrolysis oil intermediates. 2: Develop post-pyrolysis technologies that enable the commercial upgrading of pyrolysis oils into marketable fuels and/or chemicals. 3: Develop scalable technologies that enable commercially-viable pyrolysis oil-based products and co-products.
A three-tier developmental approach at the analytical, pilot and field scales will be followed to overcome the scientific, engineering and economic barriers that have challenged production and blending of biomass pyrolysis oils (bio-oil) into hydrocarbon fuels. In doing so three specific thrust areas including catalytic pyrolysis, reactive/co-reactant assisted pyrolysis, and upgrading of pyrolysis oils produced from these processes, already advanced at ARS, will be strengthened. The step-wise approach includes (i) the quest for novel processing strategies that address bio-oil stability issues directly at the farm site; (ii) enabling robust catalytic deoxygenation processes that will allow for effective separation of critical (valuable or detrimental) chemical species present within bio-oils; (iii) production of an intermediate bio-oil product that can support interim markets (e.g. home heating oil) and; (iv) production of hydrocarbons suitable for refining into fuels and for manufacture of specialty chemicals. Additionally, extensive physical and chemical property data will be collected to enable operations from the farm to the refinery. Data will be used to demonstrate compatibility of the liquid hydrocarbon product with petroleum refining unit operations and for economic and environmental assessment of the process life cycle.
Obj. 1: (1) For catalytic fast pyrolysis we have determined the role of biomass iron salts and iron added to HZSM-5 catalysts in production and selectivity of aromatic hydrocarbons. We have also screened several metal (Ga, Mo, Zn, Ni) modified HZSM-5 catalysts for their effectiveness in increasing yield of selectivity of aromatic hydrocarbons via catalytic fast pyrolysis (CFP). (2) Implemented pilot scale ex situ catalytic pyrolysis capability interfacing with existing pyrolysis process development unit (PDU). Began studies targeting production of aromatic hydrocarbons and phenolics from ex situ CFP. (3) As part of the NIFA funded Biomass Research & Development Initiative project (FarmBio3) for which we are the principal investigator institution, working with our collaborators (U. of Oklahoma) we elucidated the role of Si/Al ratio of HZSM-5 and pore size in HZSM-5 catalyzed fast pyrolysis. (4) In reactive atmosphere pyrolysis (tail gas reactive pyrolysis, TGRP) we have begun to study the effect of various reactive gases (H2, CO, etc.) on switchgrass pyrolysis behavior. (5) We have also studied the combination of TGRP with co-reactant pyrolysis. In one example, we have studied the co-TGRP pyrolysis of biomass and agricultural polyethylene wastes and produced pyrolysis liquids on the pilot scale. In a second example, we have also produced high quality pyrolysis liquids from the TGRP of guayule bagasse and leaves. This solved a previous problem in pyrolysis processing of guayule residues that produced pyrolysates that were chemically favorable with high energy content but of such high viscosity that they were useless. TGRP of guayule produced low viscosity, low oxygen, and high energy bio-oils. These studies also allowed us to elucidate the roles of co-reactants such as hydrocarbon plant rubber and resins and nitrogen releasing protein in the TGRP process. In a third example, a highly-proteinaceous algae feedstock was successfully converted to bio-oil under TGRP conditions. (6) A large collection of switchgrass, big bluestem, and indian grass accessions have been characterized for ash content, mineral content, and pyrolysis products. All these data were used for calibration and optimization of NIR chemometric models for compositional analysis and prediction of pyrolysis behavior of these grasses. This work was done in collaboration with NIFA-AFRI funded coordinated agricultural project (CAP) entitled “Sustainable Production and Distribution of Bioenergy for the Central USA (CenUSA)”, located at Iowa State University. (7) We completed analysis of a set of 9 switchgrass cultivars grown on three different sites in New Jeresy to determine cultivar and environmental effects on biomass composition and fast and catalytic pyrolysis product yield. This work was done in collaboration with NIFA funded CAP at Penn State University, Northeast Woody/Warm-season Biomass Consortium (NewBio). Obj. 2: (1) We characterized the solid residue remaining after bio-oil distillation, and made determinations for their applications towards fuels production and/or coproducts. Bio-oil feedstocks were found to affect the diversity of products obtained. (2) We developed a process for converting the bio-oil solid residues post-distillation into calcined coke, which serves as a valuable co-product to replace the petroleum-derived equivalent. (3) Through several examples, we have demonstrated the efficiency of hydrodeoxygenation (HDO) for upgrading TGRP bio-oil into fuel hydrocarbons. One example involves guayule biomass, wherein cuts of gasoline, jet, and diesel-grade hydrocarbons were successfully produced. Another example involves algae TGRP oils, wherein a single catalyst was able to remove both oxygen and nitrogen in one step. The finished product consisted primarily of diesel-grade hydrocarbons and some gasoline. (4) We demonstrated that simple water-based extraction processes can efficiently separate hydrocarbons from oxygenated components of TGRP bio-oil distillates. In turn, the hydrocarbons only require simple cheap catalysts like nickel to upgrade under very mild conditions. (5) As part of FarmBio3, working with our collaborators (University of Delaware) a kinetic model for oxygen removal from bio-oil compounds has been developed, which will be used to determine optimal combinations of metals for deoxygenation; (University of South Carolina; Villanova University) various combinations of metal catalysts of controlled size have been synthesized on modified supports; (University of Maine) catalysts have been tested for deoxygenation of a model bio-oil compound. Based on performances from these screening tests, specific catalysts have been selected for deoxygenation testing with bio-oil. Obj. 3: As part of FarmBio3 the Combustion Reduction Integrated Pyrolysis System (CRIPS) and other reactors are currently under development—we have: (1) made significant progress in completing the construction of the 2 metric ton per day CRIPS demonstration unit and commissioning it. Operation of the combustion heat-up system is reliable and consistent. Solids media circulation between the twin fluidized beds, tail-gas recirculation, and electrostatic precipitator operation systems among other components of the system have been successfully demonstrated. We have since completed several improvements including heat recuperation to alleviate char & tar buildup. Initial bio-oil from switchgrass and oak has been produced. (2) To improve our smaller (5 kg/hr) process development unit (PDU) we have completed design of an intermediate-scale fast pyrolysis unit (ca. 10kg/h capacity). This apparatus can be configured as an analog to the CRIPS reactor as well as the existing 5 kg/h PDU. (3) Development of an even smaller bench scale (ca 0.3 kg/h) fast pyrolysis unit has just been completed. This apparatus is designed to allow for frequent short duration pyrolysis trials with an actual fluidized bed—as opposed to micro-scale tests that do not necessarily predict the behavior of feed materials in a bona fide fluid bed reactor. (4) To seek immediate utilization of produced pyrolysis oil we seek applications in the boiler fuel markets. For this a pyrolysis combustion test rig including spray atomization systems and a furnace for testing burners (industrially available or custom designed) up to 300,000 Btu/h has been developed. A dual-fuel (fuel oil and gaseous fuels) industrial burner has been acquired and modified to fire bio-oil blends with diesel and ethanol. To date blends containing up to 40% bio-oil (balance ethanol) have been successfully fired with this test rig.
1. Production of fuels and chemicals from guayule feedstock. Guayule (Parthenium argentatum) is a woody desert shrub cultivated in the southwestern United States as a source of natural rubber, organic resins, and high energy biofuel feedstock from crop residues. ARS researchers at Wyndmoor, Pennsylvania, used guayule bagasse, the residual biomass after latex extraction as feedstock in a pyrolysis process that employs a reactive gas environment to formulate a special intermediate bio-oil product that allows use of conventional hydro-treating with conventional noble metal catalysts and a simple distillation process to synthesize hydrocarbon (drop-in) fuels. The said guayule-bagasse tail gas reactive pyrolysis (TGRP) process encompasses pyrolyzing the guayule bagasse in a reactor in the presence of a reactive and flammable tail gas generated in the pyrolysis process and without the use of catalyst. With this process they were able to produce bio-oil with much less problematic oxygen content than most bio-oils, in organic yields of 34-40 wt% and having a high energy content of 31-37.5 MJ/kg. When they further processed the said bio-oil by centrifugation followed by a continuous hydro-treatment over a common noble metal (Pt, Ru or Pd) on a carbon support, they obtained a liquid comprising 66% gasoline range hydrocarbons. This breakthrough was the subject of a patent application filed with the USPTO entitled BIO-OILS AND METHODS OF PRODUCING BIO-OILS FROM GUAYULE BAGASSE AND/OR LEAVES, (Docket #0099.14).
2. Production of biorenewable calcined coke. A pyrolysis-based refinery must produce other valuable chemicals alongside fuel in order to financially succeed, similar to the model used in the petroleum industry. When heated to very high temperatures (>1200 degrees C), petroleum coke reacts to become nearly pure carbon with many useful physical characteristics (termed "calcined petroleum coke", CPC). Global producers of aluminum and steel rely on CPC for their production, and their demand for better CPC continues to increase, but, increasingly impurities such as sulfur, nickel, and vanadium have interfered with efficient use of CPC. ARS researchers at Wyndmoor, Pennsylvania successfully converted the heaviest fractions of renewable pyrolysis bio-oil, recovered after distillation of the volatiles free and of the said impurities into a product similar to CPC but with improved chemical properties. The technology is the subject of a recently-filed provisional patent application (DN: 0126.14) and a manuscript currently under revision (Biomass and Bioenergy, ARIS log#308470). Furthermore an MTA has been established and an MTRA is currently in preparation with Rio Tinto Alcan, a global consumer of calcined coke, who has expressed continued interest in cooperative research and development on said technology with ARS.
Boateng, A.A., Mullen, C.A., Elkasabi, Y.M., Mcmahan, C.M. 2015. Guayule (parthenium argentatum) pyrolysis biorefining: production of hydrocarbon compatible bio-oils from guayule bagasse via tail-gas reactive pyrolysis. Fuel. 158:948-956.
Kannapu, H.P., Mullen, C.A., Elkasabi, Y.M., Boateng, A.A. 2015. Catalytic transfer hydrogenation for stabilization of bio-oil oxygenates: reduction of p-cresol and furfural over bimetallic Ni-Cu catalysts using isopropanol. Fuel Processing Technology. 137:220-228.
Dorado, C., Mullen, C.A., Boateng, A.A. 2014. Origin of carbon in aromatic and olefin products derived from HZSM-5 catalyzed co-pyrolysis of cellulose and plastics via isotopic labeling. Applied Catalysis B: Environmental. 162:338-345.
Mullen, C.A., Boateng, A.A., Dadson, R.B., Hashem, F.M. 2015. Biological mineral range effects on biomass conversion to aromatic hydrocarbons via catalytic fast pyrolysis over HZSM-5. Energy and Fuels. 28:7014-7024.
Elkasabi, Y.M., Mullen, C.A., Boateng, A.A. 2014. Distillation and isolation of commodity chemicals from Bio-oil made by tail-gas reactive prolysis. ACS Sustainable Chemistry & Engineering. 2(8):2042-2052.
Keedy, J., Prymak, E., Macken, N., Pourhashem, G., Spatari, S., Mullen, C.A., Boateng, A.A. 2014. An exergy based assessment of the production and conversion of switchgrass, equine waste and forest residue to bio-oil using fast pyrolysis. Journal of Industrial and Engineering Chemical Research. 54:529-539.
Pighinelli, A.L., Boateng, A.A., Mullen, C.A., Elkasabi, Y.M. 2014. Evaluation of Brazilian biomasses as potential feedstocks for fuel production via fast pyrolysis. Energy for Sustainable Development. 21:42-50.
Martin, J.A., Mullen, C.A., Boateng, A.A. 2014. Maximizing the stability of pyrolysis oil/diesel fuel emulsions. Energy and Fuels. 28(9):5918-5929.
Serapiglia, M., Mullen, C.A., Boateng, A.A., Cortese, L.M., Bonos, S.A., Hoffman, L. 2015. Evaluation of the impact of compositional differences in switchgrass genotypes on pyrolysis product yield. Industrial Crops and Products. 74:957-968.
Mullen, C.A., Boateng, A.A. 2015. Production of aromatic hydrocarbons via catalytic pyrolysis of biomass over fe-modified HZSM-5 zeolites. ACS Sustainable Chemistry & Engineering. 3:1623-1631.