M. Clayton Wheeler

Liquid hydrocarbon fuels from cellulosic feedstocks via thermal deoxygenation of levulinic acid and formic acid salt mixtures

Formic acid is demonstrated as a hydrogen source in a solid reaction system by first stabilizing the acid as a calcium salt which then decomposes at temperatures of relevance in pyrolytic reactions. High yields of deoxygenated hydrocarbons are produced by thermal decomposition of formic and levulinic acid mixtures where the optimum feed stoichiometry is consistent with that of cellulose hydrolysis and dehydration. The method promises a high-yield, robust, low-pressure, non-catalytic route for converting biomass hydrolyzates to hydrocarbon mixtures which are similar to petroleum crude oils.

Calcium-catalyzed pyrolysis of lignocellulosic biomass components

The present study examines the effect of calcium pretreatment on pyrolysis of individual lignocellulosic compounds. Previous work has demonstrated that the incorporation of calcium compounds with the feedstock prior to pyrolysis has a significant effect on the oxygen content and stability of the resulting oil. The aim of this work was to further explore the chemistry of calcium-catalyzed pyrolysis. Bench-scale pyrolysis of biomass constituents, including lignin, cellulose and xylan is performed and compared to the oils produced from pyrolysis of the same components after calcium pretreatment. The resulting oils were analyzed by quantitative GC-MS and SEC. These analyses, together with data collected from previous work provide evidence which was used to develop proposed reaction pathways for pyrolysis of calcium-pretreatment biomass.

Femtomolar isothermal desorption using microhotplate sensors

The authors describe a technique that utilizes the fast heating rates (106K∕s) of a microhotplate sensor along with a calibrated thermal desorption system to determine the initial coverage and kinetic parameters using isothermal desorption on a millisecond time scale. Models for isothermal desorption including both pumping and desorption rate effects are presented for zero, first, and second order kinetics. Analysis of the first order model illustrates the domain of the desorption, pumping speed, and heating rate time constants that permit the desorption parameters to be estimated from the mass spectrometer signal. The technique is demonstrated using isothermal temperature programed desorption of benzoic acid from a single SnO2 covered microhotplate at surface temperatures ranging from 296to347K. The data indicate that desorption is best represented by first order kinetics. The first order preexponential factor and the desorption energy in the zero coverage limit are determined to be 1×1017s−1 and 97kJ∕mo...

Formate assisted pyrolysis of pine sawdust for in-situ oxygen removal and stabilization of bio-oil.

Pine sawdust was pretreated with several calcium compounds and then pyrolyzed in a fluidized bed pyrolysis reactor at 500 °C. The catalytic action of the calcium compounds varies depending on the anion. Analysis of pyrolysis gas, liquid and char yields and compositions demonstrates that calcium sulfate is inert during pyrolysis while calcium formate, carbonate, hydroxide and oxide show significant deoxygenation activity. Of the salts which showed deoxygenation activity, calcium formate had the highest relative yield. This effect is likely attributable to the activity of calcium formate as a hydrogen donor at the pyrolysis temperature.

Aspen Plus® and economic modeling of equine waste utilization for localized hot water heating via fast pyrolysis.

Aspen Plus(®) based simulation models have been developed to design a pyrolysis process for on-site production and utilization of pyrolysis oil from equine waste at the Equine Rehabilitation Center at Morrisville State College (MSC). The results indicate that utilization of all the available waste from the sites 41 horses requires a 6 oven dry metric ton per day (ODMTPD) pyrolysis system but it will require a 15 ODMTPD system for waste generated by an additional 150 horses at the expanded area including the College and its vicinity. For this a dual fluidized bed combustion reduction integrated pyrolysis system (CRIPS) developed at USDAs Agricultural Research Service (ARS) was identified as the technology of choice for pyrolysis oil production. The Aspen Plus(®) model was further used to consider the combustion of the produced pyrolysis oil (bio-oil) in the existing boilers that generate hot water for space heating at the Equine Center. The model results show the potential for both the equine facility and the College to displace diesel fuel (fossil) with renewable pyrolysis oil and alleviate a costly waste disposal problem. We predict that all the heat required to operate the pyrolyzer could be supplied by non-condensable gas and about 40% of the biochar co-produced with bio-oil. Techno-economic Analysis shows neither design is economical at current market conditions; however the 15 ODMTPD CRIPS design would break even when diesel prices reach

Preparation and Characterization of ALD TiN Thin Films on Lithium Titanate Spinel (Li4Ti5O12) for Lithium Ion Battery Applications

11.40/gal. This can be further improved to

Fast Pyrolysis of Pine Sawdust in a Fluidized-Bed Reactor

7.50/gal if the design capacity is maintained at 6 ODMTPD but operated at 4950 h per annum.

Synthesis and characterization of atomic layer deposited titanium nitride thin films on lithium titanate spinel powder as a lithium-ion battery anode

Lithium titanate spinel (Li 4 Ti 5 O 12 , or LTS) has received an increasing level of attention as a nanopowder lithium-ion battery anode. Nanopowder electrodes may provide a higher energy density than currently available. Furthermore, the surface of the spinel nanopowder has been studied in air, under vacuum, and at varying temperatures with diffuse reflectance infrared Fourier transform spectroscopy revealing surface hydroxyls, carbonates and water. Applying a TiN thin film, a film that is both conducting and chemically inert to harmful reactions with the solvent/electrolyte, by atomic layer deposition (ALD) may enhance battery cycle life. A 200-layer film was deposited at 500 °C. We have characterized the influence of a TiN thin film on Li-ion battery performance. Total nitrogen content and transmission electron microscopy were used to verify the presence of nitrogen and formation of a thin film, respectively, on LTS. Modifying the powder with an ALD thin film coating produced an anode material with a voltage profile that demonstrated longer charge maintenance with shorter transient periods. It also held a more consistent charge capacity over varying discharge rates in coin cell testing than unmodified LTS.