Calvin Feik

Speciation of sulfur in biochar produced from pyrolysis and gasification of oak and corn stover.

The effects of feedstock type and biomass conversion conditions on the speciation of sulfur in biochars are not well-known. In this study, the sulfur content and speciation in biochars generated from pyrolysis and gasification of oak and corn stover were determined. We found the primary determinant of the total sulfur content of biomass to be the feedstock from which the biochar is generated, with oak and corn stover biochars containing 160 and 600–800 ppm sulfur, respectively. In contrast, for sulfur speciation, we found the primary determinant to be the temperature combined with the thermochemical conversion method. The speciation of sulfur in biochars was determined using X-ray absorption near-edge structure (XANES), ASTM method D2492, and scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS). Biochars produced under pyrolysis conditions at 500–600 °C contain sulfate, organosulfur, and sulfide. In some cases, the sulfate contents are up to 77–100%. Biochars produced in gasification conditions at 850 °C contain 73–100% organosulfur. The increase of the organosulfur content as the temperature of biochar production increases suggests a similar sulfur transformation mechanism as that in coal, where inorganic sulfur reacts with hydrocarbon and/or H2 to form organosulfur when the coal is heated. EDS mapping of a biochar produced from corn stover pyrolysis shows individual sulfur-containing mineral particles in addition to the sulfur that is distributed throughout the organic matrix.

Production of Hydrogen from Biomass by Pyrolysis/Steam Reforming

We successfully demonstrated that hydrogen could be efficiently produced by catalytic steam reforming of carbohydrate-derived bio-oil fractions in a fluidized bed reactor using a commercial nickel-based catalyst. Greater steam excess than that used for natural gas reforming was necessary to minimize the formation of char and coke (or to gasify these carbonaceous solids) resulting from thermal decomposition of complex carbohydrate-derived compounds.

Chemical characterization and water content determination of bio-oils obtained from various biomass species using 31P NMR spectroscopy

Background: Pyrolysis is a promising approach to utilize biomass for biofuels. One of the key challenges for this conversion is how to analyze complicated components in the pyrolysis oils. Water contents of pyrolysis oils are normally analyzed by Karl Fischer titration. The use of 2-chloro-4,4,5,5,-tetramethyl-1,3,2-dioxaphospholane followed by 31P NMR analysis has been used to quantitatively analyze the structure of hydroxyl groups in lignin and whole biomass. Results:31P NMR analysis of pyrolysis oils is a novel technique to simultaneously characterize components and analyze water contents in pyrolysis oils produced from various biomasses. The water contents of various pyrolysis oils range from 16 to 40 wt%. The pyrolysis oils obtained from Loblolly pine had higher guaiacyl content, while that from oak had a higher syringyl content. Conclusion: The comparison with Karl Fischer titration shows that 31P NMR could also reliably be used to measure the water content of pyrolysis oils. Simultaneously with analysis of water content, quantitative characterization of hydroxyl groups, including aliphatic, C-5 substituted/syringyl, guaiacyl, p-hydroxyl phenyl and carboxylic hydroxyl groups, could also be provided by 31P NMR analysis.

Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis

With oak and pine feedstocks, the Gasification of Biomass to Hydrogen project maximizes hydrogen production using the Full Stream Reformer during water-gas shift fixed-bed reactor testing. Results indicate that higher steam-to-biomass ratio and higher thermal cracker temperature yield higher hydrogen concentration. NRELs techno-economic models and analyses indicate hydrogen production from biomass may be viable at an estimated cost of

Hydrogen by catalytic steam reforming of liquid byproducts from biomass thermoconversion processes

1.77/kg (current) and

Pilot-Scale Gasification of Corn Stover, Switchgrass, Wheat Straw, and Wood: 1. Parametric Study and Comparison with Literature

1.47/kg (advanced in 2015). To verify these estimates, NREL used the Thermochemical Process Development Unit (TCPDU), an integrated system of unit operations that investigates biomass thermochemical conversion to gaseous and liquid fuels and chemicals.